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A Multicenter Phase II Study of Pazopanib in Patients with Unresectable Dermatofibrosarcoma Protuberans

Open ArchivePublished:September 18, 2020DOI:https://doi.org/10.1016/j.jid.2020.06.039
      Dermatofibrosarcoma protuberans (DFSP) is a soft-tissue sarcoma characterized by a high risk of local infiltration. The identification of the COL1A1-PDGFB t(17;22) translocation activating the PDGF pathway led to the use of imatinib in unresectable DFSP, with a response rate of 36–80%. Pazopanib is a multitarget tyrosine kinase inhibitor approved for soft-tissue sarcomas. We conducted a phase II study of patients with unresectable DFSP to evaluate the efficacy and safety of pazopanib. Patients received 800 mg of pazopanib daily. The primary endpoint was the objective response rate defined as the reduction of the largest diameter of the tumor by ≥30% at 6 months or at surgery. A total of 23 patients, including one pretreated with imatinib, were enrolled. With a median follow-up of 6.2 months (interquartile range = 5.6–7.8 months), five patients (22%, 95% confidence interval = 7–22%) had a partial response to pazopanib. The best objective response rate was 30% (95% confidence interval = 13–53%) using Response Evaluation Criteria in Solid Tumors. One patient with metastatic DFSP previously treated with imatinib died after 2.4 months. Nine patients (39%) discontinued the treatment owing to adverse events. Pharmacodynamics analyses of tumor samples were conducted: the enrichment of EGF and the EGFR-associated gene panel was associated with resistance, suggesting that EGFR-targeted therapies could be a therapeutic option to explore in DFSP.

      Trial registration

      ClinicalTrials.gov identifier: NCT01059656.

      Abbreviations:

      DFSP (dermatofibrosarcoma protuberans), PDGFR (PDGF receptor), PR (partial response), RECIST (Response Evaluation Criteria in Solid Tumors), SDx (stable disease), sVEGFR-2 (soluble VEGF receptor-2), VEGFR (VEGF receptor)

      Introduction

      Dermatofibrosarcoma protuberans (DFSP) is a rare tumor accounting for 6% of soft-tissue sarcomas. DFSP is characterized by a slow growth rate and a low metastatic potential but is at risk of local infiltration and recurrence. Wide surgical excision is the standard of care, sometimes with multiple procedures required to obtain complete resection (
      • Fiore M.
      • Miceli R.
      • Mussi C.
      • Lo Vullo S.
      • Mariani L.
      • Lozza L.
      • et al.
      Dermatofibrosarcoma protuberans treated at a single institution: a surgical disease with a high cure rate.
      ). However, the management of unresectable or metastatic DFSP remains challenging. Moreover, DFSP with fibrosarcomatous transformation, which accounts for 5–15% of DFSP, is associated with an increased risk of metastases and a worse prognosis (
      • Liang C.A.
      • Jambusaria-Pahlajani A.
      • Karia P.S.
      • Elenitsas R.
      • Zhang P.D.
      • Schmults C.D.
      A systematic review of outcome data for dermatofibrosarcoma protuberans with and without fibrosarcomatous change.
      ;
      • Rutkowski P.
      • Klimczak A.
      • Ługowska I.
      • Jagielska B.
      • Wągrodzki M.
      • Dębiec-Rychter M.
      • et al.
      Long-term results of treatment of advanced dermatofibrosarcoma protuberans (DFSP) with imatinib mesylate - the impact of fibrosarcomatous transformation.
      ).
      DFSP biology is characterized in most cases by the rearrangement of chromosomes 17 and 22, involving the PDGFβ gene on chromosome 22, which is fused with the COL1A1 gene on chromosome 17 (
      • Dadone-Montaudié B.
      • Alberti L.
      • Duc A.
      • Delespaul L.
      • Lesluyes T.
      • Pérot G.
      • et al.
      Alternative PDGFD rearrangements in dermatofibrosarcomas protuberans without PDGFB fusions.
      ). The COL1A1–PDGFB fusion is transcriptionally upregulated and constitutively activates PDGF receptor (PDGFR)β and its downstream signaling pathway (
      • Giacchero D.
      • Maire G.
      • Nuin P.A.
      • Berthier F.
      • Ebran N.
      • Carlotti A.
      • et al.
      No correlation between the molecular subtype of COL1A1–PDGFB fusion gene and the clinico-histopathological features of dermatofibrosarcoma protuberans.
      ;
      • Greco A.
      • Fusetti L.
      • Villa R.
      • Sozzi G.
      • Minoletti F.
      • Mauri P.
      • et al.
      Transforming activity of the chimeric sequence formed by the fusion of collagen gene COL1A1 and the platelet derived growth factor b-chain gene in dermatofibrosarcoma protuberans.
      ;
      • Simon M.P.
      • Pedeutour F.
      • Sirvent N.
      • Grosgeorge J.
      • Minoletti F.
      • Coindre J.M.
      • et al.
      Deregulation of the platelet-derived growth factor B-chain gene via fusion with collagen gene COL1A1 in dermatofibrosarcoma protuberans and giant-cell fibroblastoma.
      ). Thus, the first TKR inhibitor approved in unresectable DFSP was imatinib, which targets PDGFR among other TKRs. This drug has shown efficacy in advanced DFSP with a response rate of 36–90% and a progression-free survival ranging from 11 months to 1.7 years (
      • McArthur G.A.
      • Demetri G.D.
      • van Oosterom A.
      • Heinrich M.C.
      • Debiec-Rychter M.
      • Corless C.L.
      • et al.
      Molecular and clinical analysis of locally advanced dermatofibrosarcoma protuberans treated with imatinib: Imatinib Target Exploration Consortium Study B2225.
      ;
      • Rutkowski P.
      • Van Glabbeke M.
      • Rankin C.J.
      • Ruka W.
      • Rubin B.P.
      • Debiec-Rychter M.
      • et al.
      Imatinib mesylate in advanced dermatofibrosarcoma protuberans: pooled analysis of two phase II clinical trials.
      ;
      • Stacchiotti S.
      • Pantaleo M.A.
      • Negri T.
      • Astolfi A.
      • Tazzari M.
      • Dagrada G.P.
      • et al.
      Efficacy and biological activity of imatinib in metastatic dermatofibrosarcoma protuberans (DFSP).
      ), including in the neoadjuvant setting (
      • Kérob D.
      • Porcher R.
      • Vérola O.
      • Dalle S.
      • Maubec E.
      • Aubin F.
      • et al.
      Imatinib mesylate as a preoperative therapy in dermatofibrosarcoma: results of a multicenter phase II study on 25 patients.
      ;
      • Ugurel S.
      • Mentzel T.
      • Utikal J.
      • Helmbold P.
      • Mohr P.
      • Pföhler C.
      • et al.
      Neoadjuvant imatinib in advanced primary or locally recurrent dermatofibrosarcoma protuberans: a multicenter phase II DeCOG trial with long-term follow-up.
      ). However, imatinib does not provide sufficient tumor regression in some patients, and secondary resistance may develop (
      • Rutkowski P.
      • Van Glabbeke M.
      • Rankin C.J.
      • Ruka W.
      • Rubin B.P.
      • Debiec-Rychter M.
      • et al.
      Imatinib mesylate in advanced dermatofibrosarcoma protuberans: pooled analysis of two phase II clinical trials.
      ;
      • Stacchiotti S.
      • Pantaleo M.A.
      • Negri T.
      • Astolfi A.
      • Tazzari M.
      • Dagrada G.P.
      • et al.
      Efficacy and biological activity of imatinib in metastatic dermatofibrosarcoma protuberans (DFSP).
      ), underlying the need for alternative therapeutic strategies (
      • Fu Y.
      • Kang H.
      • Zhao H.
      • Hu J.
      • Zhang H.
      • Li X.
      • et al.
      Sunitinib for patients with locally advanced or distantly metastatic dermatofibrosarcoma protuberans but resistant to imatinib.
      ;
      • Kamar F.G.
      • Kairouz V.F.
      • Sabri A.N.
      Dermatofibrosarcoma protuberans (DFSP) successfully treated with sorafenib: case report.
      ).
      Angiogenesis plays a critical role in tumor growth, invasion, and metastasis. In soft-tissue sarcoma, the interaction between VEGF and its main receptor VEGF receptor (VEGFR)-2 promotes tumor progression and is associated with more advanced tumor grades and worse prognosis (
      • Chao C.
      • Al-Saleem T.
      • Brooks J.J.
      • Rogatko A.
      • Kraybill W.G.
      • Eisenberg B.
      Vascular endothelial growth factor and soft tissue sarcomas: tumor expression correlates with grade.
      ;
      • Iyoda A.
      • Hiroshima K.
      • Baba M.
      • Fujisawa T.
      • Yusa T.
      • Ohwada H.
      Expression of vascular endothelial growth factor in thoracic sarcomas.
      ). In DFSP, in addition to PDGFR, NRP1, a coreceptor of VEGFR-2, was significantly overexpressed (
      • Baird K.
      • Davis S.
      • Antonescu C.R.
      • Harper U.L.
      • Walker R.L.
      • Chen Y.
      • et al.
      Gene expression profiling of human sarcomas: insights into sarcoma biology.
      ), and we observed that VEGFR-2 was overexpressed at the protein level in a series of 14 DFSP tumors (S. Mourah, PharmD, PhD, unpublished data, December 2008). These results suggest that targeting VEGFR-2 could be an alternative therapeutic approach in DFSP.
      Pazopanib, a TKR inhibitor, exerts antiangiogenic effects by inhibiting VEGFRs with high affinity (VEGFR-1/2/3). Several lines of data led us to hypothesize that pazopanib could be an effective therapeutic option in DFSP. First, in addition to VEGFR, pazopanib targets PDGFR, the main driver of DFSP biology, as well as fibroblast GF receptor and c-KIT (
      • Sloan B.
      • Scheinfeld N.S.
      Pazopanib, a VEGF receptor tyrosine kinase inhibitor for cancer therapy.
      ). Second, pazopanib was shown to be efficacious in other advanced soft-tissue sarcomas in a phase III trial, with a progression-free survival of 4.6 months (vs. 1.5 months in the placebo arm) (
      • Sleijfer S.
      • Ray-Coquard I.
      • Papai Z.
      • Le Cesne A.
      • Scurr M.
      • Schöffski P.
      • et al.
      Pazopanib, a multikinase angiogenesis inhibitor, in patients with relapsed or refractory advanced soft tissue sarcoma: a phase II study from the European Organisation for Research and Treatment of Cancer-soft tissue and bone sarcoma group (EORTC study 62043).
      ;
      • van der Graaf W.T.
      • Blay J.Y.
      • Chawla S.P.
      • Kim D.W.
      • Bui-Nguyen B.
      • Casali P.G.
      • et al.
      Pazopanib for metastatic soft-tissue sarcoma (PALETTE): a randomised, double-blind, placebo-controlled phase 3 trial.
      ), and is now approved as a second-line treatment. More recently, pazopanib showed efficacy in advanced solitary fibrous tumors, a rare subset of soft-tissue sarcomas with sensitivity to antiangiogenic drugs (
      • Martin-Broto J.
      • Stacchiotti S.
      • Lopez-Pousa A.
      • Redondo A.
      • Bernabeu D.
      • de Alava E.
      • et al.
      Pazopanib for treatment of advanced malignant and dedifferentiated solitary fibrous tumour: a multicentre, single-arm, phase 2 trial.
      ). Finally, pazopanib was investigated in gastrointestinal stromal tumors, which, similar to DFSP, are treated with imatinib as first-line therapy. Pazopanib showed efficacy in patients with gastrointestinal stromal tumors with prior resistance to imatinib. The progression-free survival with pazopanib was 3.4 months versus 2.3 months for the best supportive care (
      • Mir O.
      • Cropet C.
      • Toulmonde M.
      • Cesne A.L.
      • Molimard M.
      • Bompas E.
      • et al.
      Pazopanib plus best supportive care versus best supportive care alone in advanced gastrointestinal stromal tumours resistant to imatinib and sunitinib (PAZOGIST): a randomised, multicentre, open-label phase 2 trial.
      ). Recently, anecdotal cases suggested that pazopanib might be effective in DFSP (
      • Miyagawa T.
      • Kadono T.
      • Kimura T.
      • Saigusa R.
      • Yoshizaki A.
      • Miyagaki T.
      • et al.
      Pazopanib induced a partial response in a patient with metastatic fibrosarcomatous dermatofibrosarcoma protuberans without genetic translocations resistant to mesna, doxorubicin, ifosfamide and dacarbazine chemotherapy and gemcitabine-docetaxel chemotherapy.
      ), although no prospective studies have been reported.
      We conducted a phase II trial of pazopanib in the treatment of unresectable DFSP designed to assess the efficacy of pazopanib in DFSP and to identify the biomarkers associated with response.

      Results

      Patient characteristics

      Between July 2010 and February 2014, 23 patients with unresectable DFSP were enrolled from nine centers in France. Table 1 shows the patient and tumor clinicopathological characteristics. A total of 18 patients had primary DFSP, 4 had recurrent DFSP, and 1 had metastatic DFSP. Four patients had previous surgery, and one patient had previously been treated with imatinib. A fibrosarcomatous transformation was detected in six patients (26%). The presence of the COL1A1–PDGFB gene fusion was found in 18 patients (not evaluable in 5 patients). All cases of fibrosarcomatous DFSP harbored the COL1A1–PDGFB fusion.
      Table 1Patients and Tumor Characteristics at Baseline
      Patients Characteristicn (%)
      Sex
       Male16 (70)
       Female7 (30)
      Age, median (min; max), y48 (28; 77)
      ECOG
       021 (91)
       12 (9)
      Disease stage
       Primary site18 (78)
       Local recurrence4 (17)
       Metastatic disease1 (4)
      Fibrosarcomatous DFSP6 (26)
      Unresectable DFSP23 (100)
      Location of the primary tumor
       Trunk12 (52)
       Head or neck8 (35)
       Upper limbs2 (9)
       Lower limbs1 (4)
      Longest diameter, median (min; max), cm6.5 (1.2; 16)
      Clinical presentation
       Plaque3 (13)
       Nodule11 (48)
       Plaque + nodule4 (17)
       Other4 (17)
       NA1
      Prior treatment
       Surgery4
       Radiotherapy0
       Imatinib1
      Abbreviations: DFSP, dermatofibrosarcoma protuberans; ECOG, Eastern Cooperative Oncology Group; max, maximum; m; NA, not available.

      Efficacy

      The median follow-up was 6.2 months (interquartile range = 5.6–7.8 months). At the final analysis, five patients (22%, 95% confidence interval = 7–22%) had a partial response (PR) following the primary outcome (reduction of the largest diameter of the tumor by ≥30% at 6 months or at surgery, if performed before 6 months). On the basis of the standard Response Evaluation Criteria in Solid Tumors (RECIST) criteria, 2 patients had a PR (9%), and 12 had stable disease (SDx) (55%) at 6 months or at surgery, and the best overall response rate until 6 months or surgery was 30% (7 patients, 95% confidence interval = 13–53%) (Figure 1a). On the basis of the World Health Organization criteria, four patients (18%) had a PR at 6 months or at surgery; the World Health Organization criteria best overall response rate until 6 months or surgery was 45% (10 patients) (Figure 1b).
      Figure thumbnail gr1
      Figure 1Tumor response. (a) Change from baseline of the largest diameter of the target lesion during study treatment (continuous lines) or after permanent discontinuation (dotted lines) in patients with response (blue) or without response (red) according to the primary criterion. (b) Maximum percentage change in tumor size from baseline to 6 months following the primary criterion (biggest diameter according to RECIST, red) and the WHO criteria (blue). One patient only had a unidimensional tumor measure and was not assessed by the WHO criteria. RECIST, Response Evaluation Criteria in Solid Tumors; WHO, World Health Organization.
      The only patient with metastatic DFSP, who was the only patient in the study previously treated with imatinib, did not respond to pazopanib and died after 2.4 months of treatment.
      Finally, 18 patients (78%) had surgery at a median time of 6.5 months from starting pazopanib (interquartile range = 5.4–7.8 months), with free pathological margins obtained for 12 patients (67%). The six patients with incomplete surgery underwent additional surgery. Overall, 14 of the 18 patients with surgery finally had complete resection with free margins (61% of the total population).
      Among the patients with fibrosarcomatous DFSP (n = 6), two had a PR at 6 months or at surgery following the primary outcome, and four patients had PR as the best response following standard RECIST criteria. Finally, four patients with fibrosarcomatous DFSP underwent surgery, two of whom had a complete resection, and two of whom required adjuvant radiotherapy.

      Safety and QOL

      The median duration of pazopanib treatment was 3.8 months (interquartile range = 2.1–6.0 months). Treatment was discontinued because of adverse events (n = 9) or progression (n = 7). All the 23 patients (100%) experienced grade ≥2 clinical or biological adverse events, and 17 (74%) experienced grades 3–4 adverse events (Table 2). Gastrointestinal disorders, hypertension, fatigue, and transaminitis were the most frequently reported events. Grades 3–4 adverse events were transaminitis (6; 26%), cholestasis (3; 13%), hemolytic and uremic syndrome (one grade 4), and nephrotic syndrome (one grade 4). No drug-related death occurred. Nine patients (39%) discontinued pazopanib for toxicity because of transaminitis (n = 4), renal toxicity (n = 2), neutropenia (n = 1), hypertension (n = 1), and diarrhea (n = 1). Adverse events led to reduced dosing and temporary drug withdrawal for 11 (48%) and 6 patients (26%), respectively.
      Table 2Treatment-Related Adverse Events
      Adverse eventsTotal n (%)Grade 2 n (%)Grade 3–4 n (%)
      Gastrointestinal
       Diarrhea11 (48)6 (26)0
       Abdominal pain8 (35)7 (30)0
       Dysgeusia3 (13)2 (9)0
       Vomiting2 (9)2 (9)0
       Anorexia2 (9)1 (4)0
       Constipation1 (4)00
      Cutaneous
       Hair depigmentation10 (43)1 (4)0
       Cutaneous rash5 (22)2 (9)0
       Alopecia4 (17)00
       Hand-foot syndrome3 (13)3 (13)0
      Renal
       Hemolytic and uremic syndrome1 (4)01 (4)
       Nephrotic syndrome1 (4)01 (4)
       Creatinine increased4 (17)01 (4)
      Liver
       Transaminitis19 (83)3 (13)6 (26)
       Cholestasis12 (52)2 (9)3 (13)
      Hematological
       Platelet count decrease11 (48)1 (4)0
       Neutrophil count decrease6 (26)1 (4)2 (8)
      Other
       Fatigue10 (43)4 (17)0
       Hypertension20 (87)7 (30)0
       Headache2 (9)1 (4)0
       Arthralgia2 (9)2 (9)0
       Epistaxis2 (9)1 (4)0
       Metrorrhagia1 (4)1 (4)0
      Data are presented as n (%), where n is the number of patients experiencing each adverse event.
      Significant decreases from baseline to 6 months of assessment were found for global QOL, function, and symptoms (P = 0.012, after Holm’s correction for multiple testing). In particular, the global QOL score decreased from a mean of 66.7 (SD = 29.8) at baseline to a mean of 57.4 (SD = 31.7) at 6 months. Symptoms related to adverse events such as fatigue, nausea, diarrhea, and appetite loss were more frequent on treatment (Supplementary Figure S1).

      Signaling pathways targeted by pazopanib

      We focused on VEGFR-2 as the main target of pazopanib. First, we studied the plasma level of soluble VEGFR-2 (sVEGFR-2), which was previously shown to be a biomarker modified during treatment with antiangiogenic therapy (
      • Llovet J.M.
      • Peña C.E.A.
      • Lathia C.D.
      • Shan M.
      • Meinhardt G.
      • Bruix J.
      • et al.
      Plasma biomarkers as predictors of outcome in patients with advanced hepatocellular carcinoma.
      ;
      • Peña C.
      • Lathia C.
      • Shan M.
      • Escudier B.
      • Bukowski R.M.
      Biomarkers predicting outcome in patients with advanced renal cell carcinoma: results from sorafenib phase III Treatment Approaches in Renal Cancer Global Evaluation Trial.
      ). Among the 23 patients tested, those with clinical benefit from pazopanib (PR) had significantly higher plasma levels of sVEGFR-2 at baseline than patients with SDx or progressive disease as the best response (P = 0.04) (Supplementary Figure S2a). However, the VEGFR-2 mRNA expression in tumor specimens did not significantly vary from baseline to 6 months or between the responders (PR) and the nonresponders (SDx or progressive disease as the best response) in matched tumor samples (n = 5, Supplementary Figure S2b). This finding suggests that VEGFR-2 was correctly targeted by pazopanib in patients because its soluble level was associated with the tumor response but without modifying its expression within the tumor. PDGFRB mRNA expression was not modified during treatment between the responders and the nonresponders (n = 5, Supplementary Figure S3).
      Because the genotypes of VEGFRs have been reported to be associated with sVEGFR-2 levels or with responses to tyrosine kinase inhibitors, including pazopanib (
      • Beuselinck B.
      • Jean-Baptiste J.
      • Schöffski P.
      • Couchy G.
      • Meiller C.
      • Rolland F.
      • et al.
      Validation of VEGFR1 rs9582036 as predictive biomarker in metastatic clear-cell renal cell carcinoma patients treated with sunitinib.
      ;
      • Maitland M.L.
      • Xu C.F.
      • Cheng Y.C.
      • Kistner-Griffin E.
      • Ryan K.A.
      • Karrison T.G.
      • et al.
      Identification of a variant in KDR associated with serum VEGFR2 and pharmacodynamics of Pazopanib.
      ), we studied the VEGFR-1 (rs9582036) and VEGFR-2 (rs34231037) genotypes. No association between the VEGFR-1 genotype and response to pazopanib was found; only one patient had a VEGFR-2 mutation (AG genotype).

      Biomarkers of response to pazopanib and gene expression profiling

      To gain insight into the biological activity of pazopanib in DFSP, we measured the mRNA expression of 302 genes involved in the pathways related to VEGFR signaling, the cell cycle, and apoptosis in tumor samples using qPCR arrays. A total of 16 patients had baseline and follow-up tumor samples available (n = 11, baseline and month 1; n = 5, baseline, month 1, and month 6). Patients were classified as responders or nonresponders (PR or SDx + progressive disease as best response, respectively). No difference in gene expression was observed at baseline between the responders and the nonresponders that could not have been obtained by chance (Figure 2a).
      Figure thumbnail gr2
      Figure 2Tumor response and gene expression profiling. (a) P-values comparing the mRNA expression of 302 genes in the baseline tumor sample between responders and nonresponders in tumors. Left subpanel: cumulated distribution of P-values and FDR-adjusted q-values. The dashed line represents a P-value of 0.05. Right subpanel: quantile-to-quantile plot of observed P-values given versus what would be expected by chance only.
      (b) GSEA analyses for the six pathways with the highest enrichment score (EGF and EGFR, IFN and ILs, angiogenic factors, TIMP, Akt signaling pathway, and positive regulators of apoptosis). (c) Variation of relative mRNA expression of EGFR2, ERBB2, and EGF between baseline and 1 month in patients with response (PR) (blue) or no response (SDx or PD) (red) as best response (mean ± SD). Akt, protein kinase B; FDR, false discovery rate; GSEA, Gene Set Enrichment Analysis; NR, nonresponder; PD, progressive disease; PR, partial response; R, responder; SDx, stable disease; TIMP, tissue inhibitor metalloproteinase.
      Gene Set Enrichment Analysis was then performed by testing the enrichment of 35 subpathways involving at least three genes. The nonresponder baseline samples had the highest score enrichment for four gene signatures: EGF and receptors, IFN and/or IL, angiogenic factors, and positive regulators of apoptosis, whereas the tissue inhibitor metalloproteinase and protein kinase B gene signatures were higher in the responder samples than in the nonresponder samples. The enrichment of EGF and the EGFR-associated gene panel was significantly increased in the nonresponder samples (P = 0.035) (Figure 2b). We thus focused on the EGFR pathway components during treatment with pazopanib. After 1 month of pazopanib exposure, no difference was found in the variation of the mRNA levels of EGFR, ERBB2, and EGF between the responders (n = 10) and the nonresponders (n = 5) (Figure 2c).

      Cell-cycle analysis and response to pazopanib

      We studied the role of the p16/cyclin D-CDK4 pathway in tumors because this pathway is known to be involved in DFSP progression (
      • Eilers G.
      • Czaplinski J.T.
      • Mayeda M.
      • Bahri N.
      • Tao D.
      • Zhu M.
      • et al.
      CDKN2A/p16 loss implicates CDK4 as a therapeutic target in imatinib-resistant dermatofibrosarcoma protuberans.
      ;
      • Park S.
      • Cho S.
      • Kim M.
      • Park J.U.
      • Jeong E.C.
      • Choi E.
      • et al.
      Dermatofibrosarcoma protuberans: a retrospective study of clinicopathological features and related Akt/mTOR, STAT3, ERK, cyclin D1, and PD-L1 expression.
      ;
      • Siref A.
      • Patel V.
      • Reith J.D.
      • Balzer B.L.
      • Shon W.
      Evaluation of p16 protein expression and CDKN2A deletion in conventional and fibrosarcomatous dermatofibrosarcoma protuberans.
      ;
      • Stacchiotti S.
      • Astolfi A.
      • Gronchi A.
      • Fontana A.
      • Pantaleo M.A.
      • Negri T.
      • et al.
      Evolution of dermatofibrosarcoma protuberans to DFSP-derived fibrosarcoma: an event marked by epithelial-mesenchymal transition-like process and 22q loss.
      ). We focused on the expression of cell-cycle regulators in the tumor samples. At baseline, the mRNA level of CDKN2A (coding for p16) (n = 16) did not vary significantly between the responders and the nonresponders and was highly variable among the patients. Immunohistochemistry showed that p16 expression was lost at baseline in one patient with SDx and remained expressed in three patients with PR (Figure 3a and Supplementary Table S1).
      Figure thumbnail gr3
      Figure 3Cell-cycle analysis and response to pazopanib. (a) mRNA expression of CDKN2A at baseline in patients with response (PR, n = 6; blue) or no response (SDx or PD, n = 10; red) as best response (left) (mean ± SD) (n = 16); representative images of p16 IHC staining in two tumor samples at baseline, one with PR to pazopanib (top) and one with SDx (bottom) (right); ×400 magnification. (b) Variation of mRNA expression of CDK4, CDK1, and CCND1 in patients with response (R for PR, n = 6) or no response (NR for SDx + PD, n = 10) as best response between baseline and 1 month of treatment. Mean ± SD; unpaired t-test; ∗P < 0.05. (c) Representative images of cyclin D1 IHC staining in two cases (one PR and one SDx) at baseline and M1; ×400 magnification. IHC, immunohistochemistry; M1, 1 month; NR, nonresponder; PD, progressive disease; PR, partial response; R, responder; SDx, stable disease.
      The variation in the mRNA expression of CDK4, a cyclin-dependent kinase promoting cell-cycle progression targeted by p16, was significantly reduced in the responders compared with the nonresponders during pazopanib treatment (P = 0.02, Wilcoxon test). The mRNA expression of CDK1 and cyclin D1 was reduced as well but not significantly (Figure 3b).
      High cyclin D1 expression has been associated with worse outcomes in DFSP (
      • Park S.
      • Cho S.
      • Kim M.
      • Park J.U.
      • Jeong E.C.
      • Choi E.
      • et al.
      Dermatofibrosarcoma protuberans: a retrospective study of clinicopathological features and related Akt/mTOR, STAT3, ERK, cyclin D1, and PD-L1 expression.
      ). In our study, four patients had matched baseline and follow-up (month 1) tumor samples available for immunohistochemistry (two patients with SDx and two patients with a PR as best response). The expression of cyclin D1 was significantly decreased from baseline to month 1 in one patient with PR, whereas it remained stable in the other three patients (Figure 3c and Supplementary Table S1).
      Altogether, these results suggested the involvement of the p16/cyclin D1-CDK4 pathway in the tumor response to pazopanib, and the decreased cyclin D1 and CDK4 expression during pazopanib exposure was associated with tumor response.

      Discussion

      In our study, pazopanib induced tumor responses in 22% of patients with unresectable DFSP. Most patients underwent first-line treatment for a nonfibrosarcomatous DFSP.
      Usually, advanced DFSP is treated with imatinib as the first-line therapy, which has proven efficacy in 36–90% of patients depending on the setting (neoadjuvant or advanced) (
      • Kérob D.
      • Porcher R.
      • Vérola O.
      • Dalle S.
      • Maubec E.
      • Aubin F.
      • et al.
      Imatinib mesylate as a preoperative therapy in dermatofibrosarcoma: results of a multicenter phase II study on 25 patients.
      ;
      • McArthur G.A.
      • Demetri G.D.
      • van Oosterom A.
      • Heinrich M.C.
      • Debiec-Rychter M.
      • Corless C.L.
      • et al.
      Molecular and clinical analysis of locally advanced dermatofibrosarcoma protuberans treated with imatinib: Imatinib Target Exploration Consortium Study B2225.
      ;
      • Rutkowski P.
      • Van Glabbeke M.
      • Rankin C.J.
      • Ruka W.
      • Rubin B.P.
      • Debiec-Rychter M.
      • et al.
      Imatinib mesylate in advanced dermatofibrosarcoma protuberans: pooled analysis of two phase II clinical trials.
      ;
      • Stacchiotti S.
      • Pantaleo M.A.
      • Negri T.
      • Astolfi A.
      • Tazzari M.
      • Dagrada G.P.
      • et al.
      Efficacy and biological activity of imatinib in metastatic dermatofibrosarcoma protuberans (DFSP).
      ;
      • Ugurel S.
      • Mentzel T.
      • Utikal J.
      • Helmbold P.
      • Mohr P.
      • Pföhler C.
      • et al.
      Neoadjuvant imatinib in advanced primary or locally recurrent dermatofibrosarcoma protuberans: a multicenter phase II DeCOG trial with long-term follow-up.
      ). In a recent meta-analysis, the response rate was 60% (
      • Navarrete-Dechent C.
      • Mori S.
      • Barker C.A.
      • Dickson M.A.
      • Nehal K.S.
      Imatinib treatment for locally advanced or metastatic dermatofibrosarcoma protuberans: a systematic review.
      ), highlighting the need for alternative treatments for patients with primary or acquired resistance to imatinib. In light of our study, the response rate to pazopanib first line in DFSP is deceptive. Notably, 48% of the patients had a dose reduction, and 39% had permanent dose interruption for adverse events. This rate was higher than the rate in previous studies of pazopanib, in which 6–17% of patients had permanent discontinuation for toxicity (
      • Mir O.
      • Cropet C.
      • Toulmonde M.
      • Cesne A.L.
      • Molimard M.
      • Bompas E.
      • et al.
      Pazopanib plus best supportive care versus best supportive care alone in advanced gastrointestinal stromal tumours resistant to imatinib and sunitinib (PAZOGIST): a randomised, multicentre, open-label phase 2 trial.
      ;
      • Samuels B.L.
      • Chawla S.P.
      • Somaiah N.
      • Staddon A.P.
      • Skubitz K.M.
      • Milhem M.M.
      • et al.
      Results of a prospective phase 2 study of pazopanib in patients with advanced intermediate-grade or high-grade liposarcoma.
      ;
      • Sleijfer S.
      • Ray-Coquard I.
      • Papai Z.
      • Le Cesne A.
      • Scurr M.
      • Schöffski P.
      • et al.
      Pazopanib, a multikinase angiogenesis inhibitor, in patients with relapsed or refractory advanced soft tissue sarcoma: a phase II study from the European Organisation for Research and Treatment of Cancer-soft tissue and bone sarcoma group (EORTC study 62043).
      ;
      • van der Graaf W.T.
      • Blay J.Y.
      • Chawla S.P.
      • Kim D.W.
      • Bui-Nguyen B.
      • Casali P.G.
      • et al.
      Pazopanib for metastatic soft-tissue sarcoma (PALETTE): a randomised, double-blind, placebo-controlled phase 3 trial.
      ), probably because the acceptability of toxicity is higher in patients with metastatic disease. For several TKR inhibitors, the plasma concentration, which is related to the dose, has been associated with tumor response (
      • Mir O.
      • Cropet C.
      • Toulmonde M.
      • Cesne A.L.
      • Molimard M.
      • Bompas E.
      • et al.
      Pazopanib plus best supportive care versus best supportive care alone in advanced gastrointestinal stromal tumours resistant to imatinib and sunitinib (PAZOGIST): a randomised, multicentre, open-label phase 2 trial.
      ), suggesting that the efficacy of pazopanib might have been decreased by a low exposure at the effective dose in our study. However, the clinical benefit of pazopanib was significant in our study because 18 patients (78%) finally underwent surgery and 14 patients (61%) obtained complete resection with free pathological margins at the end of the study. A reduction in tumor size below the threshold of PR was probably sufficient for these tumors to become resectable after treatment with pazopanib.
      We performed a large analysis of mRNA expression to identify the pathways involved in the response to pazopanib. Whereas the mRNA expression of VEGFRs, the main pazopanib target, was not modified during treatment with pazopanib between the responders and the nonresponders, the plasma protein level of sVEGFR-2 was higher in the responders. In a study conducted in soft-tissue sarcoma, patients with clinical benefit from pazopanib had a lower baseline plasma VEGF than those who did not (
      • Glade Bender J.L.
      • Lee A.
      • Reid J.M.
      • Baruchel S.
      • Roberts T.
      • Voss S.D.
      • et al.
      Phase I pharmacokinetic and pharmacodynamic study of pazopanib in children with soft tissue sarcoma and other refractory solid tumors: a children’s oncology group phase I consortium report.
      ), which is consistent with our results, because sVEGFR-2 binds its ligand VEGF, thus preventing the activation of VEGFR-2 by VEGF on tumor cells. Because the tumor response was correlated with sVEGFR-2 expression, we concluded that the angiogenic pathway was more prevalent in the DFSP tumors of the responders than in those of the nonresponders and was possibly involved in the tumor response induced by pazopanib.
      EGFR signaling has been associated with the progression and transformation of DFSP (
      • Osio A.
      • Xu S.
      • El Bouchtaoui M.
      • Leboeuf C.
      • Gapihan G.
      • Lemaignan C.
      • et al.
      EGFR is involved in dermatofibrosarcoma protuberans progression to high grade sarcoma.
      ). In this study, among the six patients with fibrosarcomatous DFSP, four had a PR as the best response. Moreover, the overexpression of transcripts involved in the EGF/EGFR pathway at baseline was associated with resistance to pazopanib.
      • Ugurel S.
      • Mentzel T.
      • Utikal J.
      • Helmbold P.
      • Mohr P.
      • Pföhler C.
      • et al.
      Neoadjuvant imatinib in advanced primary or locally recurrent dermatofibrosarcoma protuberans: a multicenter phase II DeCOG trial with long-term follow-up.
      observed a significant activation of EGFR in 100% of the DFSPs tested before treatment with imatinib. EGFR and pazopanib targets (VEGFR and PDGFR) share the same downstream signaling pathways, involving the MAPKs and the phosphoinositide 3-kinase pathways. In our study, an increase in baseline EGFR signaling was associated with resistance to pazopanib. Altogether, these data suggest that EGFR-targeted therapies could be an interesting option to explore in DFSP.
      Pharmacodynamics analyses also showed that the p16/cyclin D-CDK4 pathway was associated with tumor response. In DFSP, the deletion of CDKN2A and the resulting loss of P16 expression was identified in a significant proportion of DFSPs, including fibrosarcomatous DFSP, and was shown to contribute to the progression of DFSP (
      • Eilers G.
      • Czaplinski J.T.
      • Mayeda M.
      • Bahri N.
      • Tao D.
      • Zhu M.
      • et al.
      CDKN2A/p16 loss implicates CDK4 as a therapeutic target in imatinib-resistant dermatofibrosarcoma protuberans.
      ;
      • Siref A.
      • Patel V.
      • Reith J.D.
      • Balzer B.L.
      • Shon W.
      Evaluation of p16 protein expression and CDKN2A deletion in conventional and fibrosarcomatous dermatofibrosarcoma protuberans.
      ;
      • Stacchiotti S.
      • Astolfi A.
      • Gronchi A.
      • Fontana A.
      • Pantaleo M.A.
      • Negri T.
      • et al.
      Evolution of dermatofibrosarcoma protuberans to DFSP-derived fibrosarcoma: an event marked by epithelial-mesenchymal transition-like process and 22q loss.
      ). Although the number of samples was low, our results were consistent with the p16 loss found in one patient without clinical benefit from pazopanib and the remaining expression in three patients with a response.
      • Eilers G.
      • Czaplinski J.T.
      • Mayeda M.
      • Bahri N.
      • Tao D.
      • Zhu M.
      • et al.
      CDKN2A/p16 loss implicates CDK4 as a therapeutic target in imatinib-resistant dermatofibrosarcoma protuberans.
      developed a rationale for targeting CD4/CDK6 in imatinib-resistant DFSP, and we observed a strong inhibition of CDK4 expression in the patients with clinical benefit from pazopanib, both suggesting that targeting the CDK4/CDK6 axis could be a therapeutic alternative that deserves further investigation.
      Considering the rarity of this disease, we had to conduct our study in a large population that finally included locally advanced, metastatic, and fibrosarcomatous DFSP. Resistance to imatinib was too rare to be retained as an inclusion criterion. Our results are not in favor of using pazopanib as a first-line therapy considering the response rate and the toxicity profile, but its place in the armamentarium against DFSP, especially in resistance to imatinib, will remain to be defined.
      In conclusion, our results suggested that pazopanib is a therapeutic option in DFSP but with relatively poor tolerability and low response rate compared with those in previous studies with imatinib. The involvement of the EGFR signaling pathway suggests an additional therapeutic strategy that deserves further investigation.

      Materials and Methods

      Patients

      We conducted an open-label phase II multicenter trial in nine cancer centers or university hospitals in France (ClinicalTrial.gov: NCT01059656). The inclusion criteria were as follows: patients with histologically proven, unresectable DFSP, which was either primary, locally recurrent, or metastatic and measurable according to the RECIST, version 1.1; Eastern Cooperative Oncology Group performance status of ≤1; adequate hematologic, hepatic, and renal functions; and left ventricular ejection fraction within the local normal ranges (>45%). The unresectable stage of DFSP had to be assessed by a multidisciplinary team expert in sarcoma management before enrollment.
      The presence of the COL1A1–PDGFB fusion was assessed at baseline using fluorescence in situ hybridization. Patients with fibrosarcomatous DFSP were included if molecularly confirmed by the detection of the t(17;22) translocation. Patients previously treated with surgery, radiotherapy, or imatinib could be included. Exclusion criteria were patients with concomitant active cancers, other anticancer treatment within 4 weeks before enrollment, severe gastrointestinal disorders that might interfere with treatment absorption, any hemorrhagic risk or predispositions, uncontrolled hypertension, a history of cardiovascular events in the last 6 months, and expected poor compliance to treatment. The study protocol was approved by the French Ethics Committee. All patients provided written informed consent before enrollment.

      Study design

      Patients received 800 mg of pazopanib orally once daily. Dose reduction to 600 mg or 400 mg once daily was allowed in case of toxicity in accordance with good clinical practice and as defined in the protocol (i.e., recurrent grade 2 or any grade 3 toxicity that resolved to grade ≤1). Study treatment was continued until disease progression or the occurrence of unacceptable adverse events. The tumor response was assessed by investigators on the basis of physical examination at months 1, 3, and 6 and the Physician Global Assessment tool. Patients were followed up for safety through monthly clinical and biological data. Adverse events were assessed and graded according to the Common Terminology Criteria Adverse Events, version 4. QOL was assessed using the European Organization for Research and Treatment of Cancer QLQ-C30.

      Study endpoints

      The primary endpoint was the objective response rate, obtained from a physical examination following the RECIST requirements of the tumor at 6 months or at surgery, if performed before 6 months. PR was defined as a reduction of the largest diameter of the tumor by ≥30% from baseline, as with standard RECIST criteria, but it did not require confirmation by a follow-up assessment 4 weeks later (to avoid an additional delay before surgery if some tumors became resectable). Secondary endpoints were as follows:
      • other parameters of efficacy assessed by physical examination according to standard RECIST criteria, version 1.1 (
        • Eisenhauer E.A.
        • Therasse P.
        • Bogaerts J.
        • Schwartz L.H.
        • Sargent D.
        • Ford R.
        • et al.
        New response evaluation criteria in solid tumours: revised RECIST guideline (version 1.1).
        ), and World Health Organization criteria (
        World Health Organization
        WHO handbook for reporting results of cancer treatment.
        ): objective response rate at 6 months or at surgery, that is, the proportion of patients still considered as in complete response or PR at 6 months or at the time of surgery, and best overall response rate, defined as the best response recorded from the start of the study treatment until 6 months or surgery;
      • safety;
      • QOL as evaluated by the European Organization for Research and Treatment of Cancer QLQ-C30, version 3.0, questionnaire at 1, 3, and 6 months;
      • correlation of tumor response with molecular analyses.

      Pharmacodynamics analyses

      Molecular analyses were performed on tumor biopsies and blood samples at baseline; at months 1, 3, and 6; or at progression. In tumor samples, total mRNA was isolated using TRIzol reagent (Thermo Fisher Scientific, Waltham, MA) according to the manufacturer’s instructions. mRNA expression was measured using the SignArrays 384 system (AnyGenes, Paris, France), including 302 genes involved in angiogenesis, the cell cycle, apoptosis, migration, and senescence, such as PDGF-A/B, PDGFRα/β, VEGF, and VEGFR-1, 2, 3, and their downstream signaling pathway components. The protein expression levels of cell-cycle components were assessed using immunohistochemistry. Formalin-fixed, paraffin-embedded tumor tissue samples were analyzed by central pathological review. Immunohistochemistry staining was performed on a BenchMark ULTRA automatic system (Roche Ventana, Oro Valley, AZ), with the anti-cyclin D1 (CliniSciences, Nanterre, France), anti-p16 (Roche Ventana), and anti-RB1 (Abcam, Cambridge, United Kingdom) antibodies, and revealed with the OptiView kit (Roche Ventana). In plasma, sVEGFR-2 was measured at baseline using a human sVEGFR-2/KDR ELISA Quantikine kit (R&D Systems, Minneapolis, MI). Single SNP genotyping of VEGFR-1 (rs9582036) and VEGFR-2 (rs34231037) was performed using commercially available TaqMan assays (Thermo Fisher Scientific, Illkirch, France).

      Statistical methods

      All the patients enrolled in the trial were included in the primary analysis, and death was considered nonresponse. The study was designed according to an exact single-stage phase II design (
      • A’Hern R.P.
      Sample size tables for exact single-stage phase II designs.
      ) and powered to detect an increase in the response rate from 20% to 50% at a one-sided 0.025 significance level with 90% power. Accordingly, the null hypothesis would be rejected if ≥10 responses would be observed out of 26 patients. Owing to difficulties in accrual, the trial was stopped after enrollment of 23 patients before any data analysis, which lowered the power to 80%.
      Gene mRNA expression was compared with the best response (complete response + PR for responders vs. SDx + progressive disease for nonresponders) using Student’s t-tests; P-values corrected to control the false discovery rate over the multiple analyses were computed (
      • Benjamini Y.
      • Hochberg Y.
      Controlling the false discovery rate: a practical and powerful approach to multiple testing.
      ). In addition, Gene Set Enrichment Analysis was used to interpret gene expression data (
      • Subramanian A.
      • Tamayo P.
      • Mootha V.K.
      • Mukherjee S.
      • Ebert B.L.
      • Gillette M.A.
      • et al.
      Gene set enrichment analysis: a knowledge-based approach for interpreting genome-wide expression profiles.
      ).
      All analyses used R statistical software, version 3.3.3 (The R Foundation for Statistical Computing, Vienna, Austria).

      Data availability statements

      The gene expression data discussed in this article have been deposited in National Center for Biotechnology Information’s Gene Expression Omnibus and are accessible through Gene Expression Omnibus series accession number GSE150787 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE150787).
      The study protocol including the statistical analysis plan will be shared on request.
      The initial protocol did not include the possibility of sharing data of participants with researchers not involved in the study. However, access to individual patient data that underline the results reported in this article, after deidentification, can be granted on reasonable request. A protocol should then be submitted to the corresponding author and will be transmitted to the principal investigator of the trial to be examined by the trial scientific committee. After evaluation of the scientific and medical content of the protocol, if access is granted, ethical clearance will be sought from the ethical review board (Comités de Protection des Personnes) by the principal investigator.

      Conflict of Interest

      MB received honoraria from Bristol-Myers Squibb, Leo Pharma, Takeda Pharmaceutical, Innate Pharma, outside of the submitted work. CL is in the board of Avantis Medical Systems; received research grants or honoraria from Roche Holdings AG, Bristol-Myers Squibb, Merck Sharp & Dohme, GlaxoSmithKline, Novartis, Amgen, Laboratoires Pierre Fabre, Pfizer, Incyte Corporation, Merck Serono, and Sanofi; and received travel accommodations from Roche, Bristol-Myers Squibb, and Merck Sharp & Dohme, outside of the submitted work. JD received travel accommodations from Laboratoires Pierre Fabre and Roche Holdings AG. FP reported grants from Novartis Pharma, Merck Serono, and Roche Holdings AG and personal fees from AstraZeneca, outside of the submitted work. SM received research grants or honoraria from Roche Holdings AG, Janssen, Bristol-Myers Squibb, Biocartis, and Novartis, outside of the submitted work. NM received research grants, honoraria, and travel accommodation from Roche, Novartis, GlaxoSmithKline, Bristol-Myers Squibb, Merck Sharp & Dohme, Amgen, Merck GmBH, Incyte Corporation, Laboratoires Pierre Fabre, Sun Pharma, AbbVie, and Sanofi, outside of the submitted work. LM reports travel for congress from Bristol-Myers Squibb, Roche, Novartis, Merck Sharp & Dohme. EV received grants from Abbott, AstraZeneca, Bayer Health Care, Bristol-Myers Squibb, Daiichi-Sankyo, and Pfizer. The remaining authors state no conflicts of interest.

      Acknowledgments

      This work received a grant from Novartis to support over cost and promoter support from Assistance Publique-Hôpitaux de Paris.

      Author Contributions

      Conceptualization: CL, RP, SM; Formal Analysis: RP, SM, MB, FP; Investigation: NM, HA, FB, BG, TJ, MTL, SD, LM, CL; Methodology: RP; Project Administration: ZG, LDM, EV; Supervision: CL; Writing - Original Draft Preparation: JD; Writing - Review and Editing: JD, CL, SM, RP

      Supplementary Materials

      Figure thumbnail fx1
      Supplementary Figure S1QOL assessment during treatment with pazopanib.
      Global QOL and individual symptoms following the QLQ-C30, version 3.0 at baseline and last assessment up to 6 mos. mo, month.
      Figure thumbnail fx2
      Supplementary Figure S2VEGFR-2 expression and tumor response. (a) Plasma sVEGFR-2 expression at baseline for patients with PR (n =7) or SDx/PD (n = 16) as best response. Median (IQR); unpaired t-test; ∗P < 0.05. (b) Variation of mRNA expression of VEGFR-2 in tumors between M0 and M6 in patients with PR (blue, n = 2) or PD (red, n = 3) as best response. IQR, interquartile range; M0, baseline; M6, 6 months; PD, progressive disease; PR, partial response; SDx, stable disease; sVEGFR-2, soluble VEGFR-2; VEGFR, VEGF receptor.
      Figure thumbnail fx3
      Supplementary Figure S3PDGFRB expression and tumor response. Variation of mRNA expression of PDGFRB in tumors between M0 and M6 in patients with PR (blue, n = 2) or PD (red, n = 3) as best response. M0, baseline; M6, 6 months; PD, progressive disease; PR, partial response.
      Supplementary Table S1IHC Staining (Percentage of Tumor Cells) for p16, Cyclin D1, and RB1 in Tumors at Baseline in Two Patients with SDx and Two Patients with PR to Pazopanib
      Tumor ResponseTime Pointp16Cyclin D1RB1
      SDxBaseline1510+ (50% nuclear)
      M11515+ (30% nuclear)
      SDxBaseline<100
      M151
      PRBaseline510
      M1105
      PRBaseline10205
      M101
      Abbreviations: IHC, immunohistochemistry; M1, month 1; PR, partial response; SDx, stable disease.

      References

        • A’Hern R.P.
        Sample size tables for exact single-stage phase II designs.
        Stat Med. 2001; 20: 859-866
        • Baird K.
        • Davis S.
        • Antonescu C.R.
        • Harper U.L.
        • Walker R.L.
        • Chen Y.
        • et al.
        Gene expression profiling of human sarcomas: insights into sarcoma biology.
        Cancer Res. 2005; 65: 9226-9235
        • Benjamini Y.
        • Hochberg Y.
        Controlling the false discovery rate: a practical and powerful approach to multiple testing.
        J R Stat Soc Series B (Methodol). 1995; 57: 289-300
        • Beuselinck B.
        • Jean-Baptiste J.
        • Schöffski P.
        • Couchy G.
        • Meiller C.
        • Rolland F.
        • et al.
        Validation of VEGFR1 rs9582036 as predictive biomarker in metastatic clear-cell renal cell carcinoma patients treated with sunitinib.
        BJU Int. 2016; 118: 890-901
        • Chao C.
        • Al-Saleem T.
        • Brooks J.J.
        • Rogatko A.
        • Kraybill W.G.
        • Eisenberg B.
        Vascular endothelial growth factor and soft tissue sarcomas: tumor expression correlates with grade.
        Ann Surg Oncol. 2001; 8: 260-267
        • Dadone-Montaudié B.
        • Alberti L.
        • Duc A.
        • Delespaul L.
        • Lesluyes T.
        • Pérot G.
        • et al.
        Alternative PDGFD rearrangements in dermatofibrosarcomas protuberans without PDGFB fusions.
        Mod Pathol. 2018; 31: 1683-1693
        • Eilers G.
        • Czaplinski J.T.
        • Mayeda M.
        • Bahri N.
        • Tao D.
        • Zhu M.
        • et al.
        CDKN2A/p16 loss implicates CDK4 as a therapeutic target in imatinib-resistant dermatofibrosarcoma protuberans.
        Mol Cancer Ther. 2015; 14: 1346-1353
        • Eisenhauer E.A.
        • Therasse P.
        • Bogaerts J.
        • Schwartz L.H.
        • Sargent D.
        • Ford R.
        • et al.
        New response evaluation criteria in solid tumours: revised RECIST guideline (version 1.1).
        Eur J Cancer. 2009; 45: 228-247
        • Fiore M.
        • Miceli R.
        • Mussi C.
        • Lo Vullo S.
        • Mariani L.
        • Lozza L.
        • et al.
        Dermatofibrosarcoma protuberans treated at a single institution: a surgical disease with a high cure rate.
        J Clin Oncol. 2005; 23: 7669-7675
        • Fu Y.
        • Kang H.
        • Zhao H.
        • Hu J.
        • Zhang H.
        • Li X.
        • et al.
        Sunitinib for patients with locally advanced or distantly metastatic dermatofibrosarcoma protuberans but resistant to imatinib.
        Int J Clin Exp Med. 2015; 8: 8288-8294
        • Giacchero D.
        • Maire G.
        • Nuin P.A.
        • Berthier F.
        • Ebran N.
        • Carlotti A.
        • et al.
        No correlation between the molecular subtype of COL1A1–PDGFB fusion gene and the clinico-histopathological features of dermatofibrosarcoma protuberans.
        J Invest Dermatol. 2010; 130: 904-907
        • Glade Bender J.L.
        • Lee A.
        • Reid J.M.
        • Baruchel S.
        • Roberts T.
        • Voss S.D.
        • et al.
        Phase I pharmacokinetic and pharmacodynamic study of pazopanib in children with soft tissue sarcoma and other refractory solid tumors: a children’s oncology group phase I consortium report.
        J Clin Oncol. 2013; 31: 3034-3043
        • Greco A.
        • Fusetti L.
        • Villa R.
        • Sozzi G.
        • Minoletti F.
        • Mauri P.
        • et al.
        Transforming activity of the chimeric sequence formed by the fusion of collagen gene COL1A1 and the platelet derived growth factor b-chain gene in dermatofibrosarcoma protuberans.
        Oncogene. 1998; 17: 1313-1319
        • Iyoda A.
        • Hiroshima K.
        • Baba M.
        • Fujisawa T.
        • Yusa T.
        • Ohwada H.
        Expression of vascular endothelial growth factor in thoracic sarcomas.
        Ann Thorac Surg. 2001; 71: 1635-1639
        • Kamar F.G.
        • Kairouz V.F.
        • Sabri A.N.
        Dermatofibrosarcoma protuberans (DFSP) successfully treated with sorafenib: case report.
        Clin Sarcoma Res. 2013; 3: 5
        • Kérob D.
        • Porcher R.
        • Vérola O.
        • Dalle S.
        • Maubec E.
        • Aubin F.
        • et al.
        Imatinib mesylate as a preoperative therapy in dermatofibrosarcoma: results of a multicenter phase II study on 25 patients.
        Clin Cancer Res. 2010; 16: 3288-3295
        • Liang C.A.
        • Jambusaria-Pahlajani A.
        • Karia P.S.
        • Elenitsas R.
        • Zhang P.D.
        • Schmults C.D.
        A systematic review of outcome data for dermatofibrosarcoma protuberans with and without fibrosarcomatous change.
        J Am Acad Dermatol. 2014; 71: 781-786
        • Llovet J.M.
        • Peña C.E.A.
        • Lathia C.D.
        • Shan M.
        • Meinhardt G.
        • Bruix J.
        • et al.
        Plasma biomarkers as predictors of outcome in patients with advanced hepatocellular carcinoma.
        Clin Cancer Res. 2012; 18: 2290-2300
        • Maitland M.L.
        • Xu C.F.
        • Cheng Y.C.
        • Kistner-Griffin E.
        • Ryan K.A.
        • Karrison T.G.
        • et al.
        Identification of a variant in KDR associated with serum VEGFR2 and pharmacodynamics of Pazopanib.
        Clin Cancer Res. 2015; 21: 365-372
        • Martin-Broto J.
        • Stacchiotti S.
        • Lopez-Pousa A.
        • Redondo A.
        • Bernabeu D.
        • de Alava E.
        • et al.
        Pazopanib for treatment of advanced malignant and dedifferentiated solitary fibrous tumour: a multicentre, single-arm, phase 2 trial.
        Lancet Oncol. 2019; 20: 134-144
        • McArthur G.A.
        • Demetri G.D.
        • van Oosterom A.
        • Heinrich M.C.
        • Debiec-Rychter M.
        • Corless C.L.
        • et al.
        Molecular and clinical analysis of locally advanced dermatofibrosarcoma protuberans treated with imatinib: Imatinib Target Exploration Consortium Study B2225.
        J Clin Oncol. 2005; 23: 866-873
        • Mir O.
        • Cropet C.
        • Toulmonde M.
        • Cesne A.L.
        • Molimard M.
        • Bompas E.
        • et al.
        Pazopanib plus best supportive care versus best supportive care alone in advanced gastrointestinal stromal tumours resistant to imatinib and sunitinib (PAZOGIST): a randomised, multicentre, open-label phase 2 trial.
        Lancet Oncol. 2016; 17: 632-641
        • Miyagawa T.
        • Kadono T.
        • Kimura T.
        • Saigusa R.
        • Yoshizaki A.
        • Miyagaki T.
        • et al.
        Pazopanib induced a partial response in a patient with metastatic fibrosarcomatous dermatofibrosarcoma protuberans without genetic translocations resistant to mesna, doxorubicin, ifosfamide and dacarbazine chemotherapy and gemcitabine-docetaxel chemotherapy.
        J Dermatol. 2017; 44: e21-e22
        • Navarrete-Dechent C.
        • Mori S.
        • Barker C.A.
        • Dickson M.A.
        • Nehal K.S.
        Imatinib treatment for locally advanced or metastatic dermatofibrosarcoma protuberans: a systematic review.
        JAMA Dermatol. 2019; 155: 361-369
        • Osio A.
        • Xu S.
        • El Bouchtaoui M.
        • Leboeuf C.
        • Gapihan G.
        • Lemaignan C.
        • et al.
        EGFR is involved in dermatofibrosarcoma protuberans progression to high grade sarcoma.
        Oncotarget. 2018; 9: 8478-8488
        • Park S.
        • Cho S.
        • Kim M.
        • Park J.U.
        • Jeong E.C.
        • Choi E.
        • et al.
        Dermatofibrosarcoma protuberans: a retrospective study of clinicopathological features and related Akt/mTOR, STAT3, ERK, cyclin D1, and PD-L1 expression.
        J Am Acad Dermatol. 2018; 79: 843-852
        • Peña C.
        • Lathia C.
        • Shan M.
        • Escudier B.
        • Bukowski R.M.
        Biomarkers predicting outcome in patients with advanced renal cell carcinoma: results from sorafenib phase III Treatment Approaches in Renal Cancer Global Evaluation Trial.
        Clin Cancer Res. 2010; 16: 4853-4863
        • Rutkowski P.
        • Klimczak A.
        • Ługowska I.
        • Jagielska B.
        • Wągrodzki M.
        • Dębiec-Rychter M.
        • et al.
        Long-term results of treatment of advanced dermatofibrosarcoma protuberans (DFSP) with imatinib mesylate - the impact of fibrosarcomatous transformation.
        Eur J Surg Oncol. 2017; 43: 1134-1141
        • Rutkowski P.
        • Van Glabbeke M.
        • Rankin C.J.
        • Ruka W.
        • Rubin B.P.
        • Debiec-Rychter M.
        • et al.
        Imatinib mesylate in advanced dermatofibrosarcoma protuberans: pooled analysis of two phase II clinical trials.
        J Clin Oncol. 2010; 28: 1772-1779
        • Samuels B.L.
        • Chawla S.P.
        • Somaiah N.
        • Staddon A.P.
        • Skubitz K.M.
        • Milhem M.M.
        • et al.
        Results of a prospective phase 2 study of pazopanib in patients with advanced intermediate-grade or high-grade liposarcoma.
        Cancer. 2017; 123: 4640-4647
        • Simon M.P.
        • Pedeutour F.
        • Sirvent N.
        • Grosgeorge J.
        • Minoletti F.
        • Coindre J.M.
        • et al.
        Deregulation of the platelet-derived growth factor B-chain gene via fusion with collagen gene COL1A1 in dermatofibrosarcoma protuberans and giant-cell fibroblastoma.
        Nat Genet. 1997; 15: 95-98
        • Siref A.
        • Patel V.
        • Reith J.D.
        • Balzer B.L.
        • Shon W.
        Evaluation of p16 protein expression and CDKN2A deletion in conventional and fibrosarcomatous dermatofibrosarcoma protuberans.
        Pathology. 2018; 50: 474-475
        • Sleijfer S.
        • Ray-Coquard I.
        • Papai Z.
        • Le Cesne A.
        • Scurr M.
        • Schöffski P.
        • et al.
        Pazopanib, a multikinase angiogenesis inhibitor, in patients with relapsed or refractory advanced soft tissue sarcoma: a phase II study from the European Organisation for Research and Treatment of Cancer-soft tissue and bone sarcoma group (EORTC study 62043).
        J Clin Oncol. 2009; 27: 3126-3132
        • Sloan B.
        • Scheinfeld N.S.
        Pazopanib, a VEGF receptor tyrosine kinase inhibitor for cancer therapy.
        Curr Opin Investig Drugs. 2008; 9: 1324-1335
        • Stacchiotti S.
        • Astolfi A.
        • Gronchi A.
        • Fontana A.
        • Pantaleo M.A.
        • Negri T.
        • et al.
        Evolution of dermatofibrosarcoma protuberans to DFSP-derived fibrosarcoma: an event marked by epithelial-mesenchymal transition-like process and 22q loss.
        Mol Cancer Res. 2016; 14: 820-829
        • Stacchiotti S.
        • Pantaleo M.A.
        • Negri T.
        • Astolfi A.
        • Tazzari M.
        • Dagrada G.P.
        • et al.
        Efficacy and biological activity of imatinib in metastatic dermatofibrosarcoma protuberans (DFSP).
        Clin Cancer Res. 2016; 22: 837-846
        • Subramanian A.
        • Tamayo P.
        • Mootha V.K.
        • Mukherjee S.
        • Ebert B.L.
        • Gillette M.A.
        • et al.
        Gene set enrichment analysis: a knowledge-based approach for interpreting genome-wide expression profiles.
        Proc Natl Acad Sci USA. 2005; 102: 15545-15550
        • Ugurel S.
        • Mentzel T.
        • Utikal J.
        • Helmbold P.
        • Mohr P.
        • Pföhler C.
        • et al.
        Neoadjuvant imatinib in advanced primary or locally recurrent dermatofibrosarcoma protuberans: a multicenter phase II DeCOG trial with long-term follow-up.
        Clin Cancer Res. 2014; 20: 499-510
        • van der Graaf W.T.
        • Blay J.Y.
        • Chawla S.P.
        • Kim D.W.
        • Bui-Nguyen B.
        • Casali P.G.
        • et al.
        Pazopanib for metastatic soft-tissue sarcoma (PALETTE): a randomised, double-blind, placebo-controlled phase 3 trial.
        Lancet. 2012; 379: 1879-1886
        • World Health Organization
        WHO handbook for reporting results of cancer treatment.
        (accessed 6 October 2020)