Surgical versus non-surgical approach in primary desmoid-type fibromatosis patients: A nationwide prospective cohort from the French Sarcoma Group

PURPOSE

The outcome of desmoid-type fibromatosis (DTF) is unpredictable. Currently, a wait-and-see approach tends to replace large en bloc resection as the first therapeutic approach. Nevertheless, there are no validated factors to guide the treatment choice.

METHOD

We conducted a prospective study of 771 confirmed cases of DTF. We analysed event-free survival (EFS) based on the occurrence of relapse after surgery, progressive disease during the wait-and-see approach, or change in therapeutic strategy. Identification of prognostic factors was performed using classical methods (log-rank test and Cox model).

RESULTS

Overall, the 2-year EFS was 56%; this value did not differ between patients undergoing an operation and those managed by the wait-and-see approach (53% versus 58%, p = 0.415). In univariate analysis, two prognostic factors significantly influenced the outcome: the nature of diagnostic sampling (p = 0.466) and primary location (p = 0.0001). The 2-year EFS was only 32% after open biopsy. The 2-year EFS was 66% for favourable locations (abdominal wall, intra-abdominal, breast, digestive viscera and lower limb) and 41% for unfavourable locations. Among patients with favourable locations, the 2-year EFS was similar in patients treated by both surgery (70%) and the wait-and-see approach (63%; p = 0.413). Among patients with unfavourable locations, the 2-year EFS was significantly enhanced in patients initially managed with the wait-and-see approach (52%) compared with those who underwent initial surgery (25%; p = 0.001).

CONCLUSION

The location of DTF is a major prognostic factor for EFS. If these findings are confirmed by independent analysis, personalised management of DTF must consider this easily obtained parameter.

Abstract LB-190: Combination of pembrolizumab and metronomic cyclophosphamide in patients with advanced sarcomas: a french sarcoma group study

Background: There is a strong rationale for immunotherapy in sarcomas. We report results of the first phase II study of PD-1 blockade with the anti-PD-1 antibody pembrolizumab in combination with metronomic chemotherapy in patients with advanced soft tissue sarcomas (STS) and gastro-intestinal stromal tumour (GIST). Methods: This is an open-label multicentre phase II study of the anti-PD-1 pembrolizumab in combination with low-dose cyclophosphamide in 4 cohorts of patients with advanced STS: leiomyosarcoma (LMS), undifferentiated pleomorphic sarcoma (UPS), gastrointestinal stromal tumour (GIST) and other sarcomas (Others). All patients received pembrolizumab 200mg IV q21 days and cyclophosphamide 50 mg BID 1 week on, 1 week off. The primary endpoint was a dual one encompassing non-progression and objective response (as per RECIST evaluation criteria v1.1) at 6 months for LMS, UPS, and Others, and 6-month non-progression for GIST. An objective response rate of 20% and/or a 6-months non-progression rate of 60% were determined as reasonable objectives for treatment meaningful effect. Findings:57 patients were included. Forty-nine were assessable for efficacy. Three patients experienced tumour shrinkage resulting in a partial response (PR) in one of them (solitary fibrous tumour). The 6-month non-progression rate was 0%, 0%, 11.1% (95% CI 2.8-48.3) and 14.3% (95% CI 1.8-42.8%) in LMS, UPS, GIST and "Others" cohorts respectively. The most frequent adverse events were grade 1 or 2 fatigue, diarrhoea, anaemia. The only patient with PR was the only one having a PDL1 positive staining in more than 10% of immune cells. Strong M2 macrophage infiltration was observed in the majority of cases and these macrophages significantly expressed the inhibitory enzyme Indoleamine2,3-dioxygenase 1 (IDO1). A significant increase of the kynurenine/tryptophane ratio was also observed in patients’ blood samples during study treatment. Conclusion: The primary endpoint of this study was not met for all cohorts. PD1 inhibition has limited activity in advanced STS and GIST. This primary resistance may be explained by an immunosuppressive tumour microenvironment resulting from macrophage infiltration and IDO1 pathway activation.

Note: This abstract was not presented at the meeting.

Citation Format: Maud Toulmonde, Nicolas Penel, Julien Adam, Christine Chevreau, Jean-Yves Blay, Axel Le Cesne, Emmanuelle Bompas, Sophie Piperno-neumann, Sophie Cousin, Thierry Ryckewaert, Alban Bessede, François Ghiringhelli, Marina Pulido, ANTOINE ITALIANO. Combination of pembrolizumab and metronomic cyclophosphamide in patients with advanced sarcomas: a french sarcoma group study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-190. doi:10.1158/1538-7445.AM2017-LB-190

Prognosis of desmoid tumors (DT): A prospective nationwide survey of 771 patients (pts)

11047

Background: Prognostic factors and optimal management of DT are not yet established. Methods: We analyzed the outcome of 771 consecutive DT pts treated between 01/2010 and 12/2016 in France. We have calculated event-free survival (EFS) defined as local relapse after surgery, progressive disease during non surgical approach or change in treatment strategy (e.g. from wait and see to systemic treatment or local treatment). Results: The sex ratio M/F was 219/552, the median age was 39 (2-90), and the median size 57 mm (4-700). 596 DT are found CTNNB1-mutated (71%). The 1st treatment was wait and see (369, 48%), surgery (343, 44%), systemic treatment (25, 3%), or radiotherapy (3, 0%). The median follow-up was 32 mo. 230 events occurred (including 1 death). The median EFS was 27 mo. After initial wait and see, pts required systemic treatment in 61 cases (15%), radiotherapy (4; 1%), cryotherapy (3; 1%), surgery (2; 0%) and radiofrequency (1, 0%). After initial surgery, DT pts required wait and see for relapse in 88 cases (25%), systemic treatment in 17 cases (5%), radiotherapy (6; 2%), cryotherapy (2; 0%) and surgery (1, 0%). Univariate analysis identified 3 factors associated with EFS: favorable locations (median not reached (NR) vs. 21 mo; p = 0.0001), nature of sampling (core needle biopsy: 31 mo; resection 26 mo and open biopsy 15 mo, p = 0.046) and superficial DT (NR vs. 28 mo, p = 0.00001). Favorable locations included: abdominal wall (236 pts), intra-abdominal (78 pts), breast (27 pts) and digestive viscera (42 pts). Chest wall (209 pts), head and neck (28 pts), lower limb (90 pts), upper limb (25 pts) and pelvis (18 pts) were all associated with poor EFS. Multivariate analysis identified only 1 prognostic factor for EFS: favorable location HR = 0.52 [0.39-0.69]. Compared to surgery, wait and see as 1st treatment was associated with better EFS in unfavorable DT locations (HR = 0.74 [0.74-0.56]; p = 0.001) but not associated with EFS in favorable locations (HR = 0.89 [0.69-1.13]; p = 0.420). Conclusions: Since primary location of DT is the major determinant of DT outcome, stratified approach according to location has to be prospectively assessed. Correlative biology analyses are warranted to better understand these findings.

Long-term survival (over 10 years) of inoperable/metastatic GISTs: A retrospective series of 141 patients (pts) of the french sarcoma group (FSG)

11041

Background: A subset of metastatic GIST exhibit very long-term survival after imatinib (IM) introduction. The aim of this study was to analyse the clinico-biological characteristics of GIST pts alive > 10 years (yrs) after diagnosis (dx) of metastases (mets) and identify possible factors associated with long-term survival. Methods: Pts were identified from 2 sarcoma databases; NetSarc and ConticaGIST. Clinical data prospectively registered in the databases were supplemented with retrospective review of medical records. Results: We identified 141 pts (75 men, 66 women) with median age 54 (17-84) yrs and median ECOG 0 (0-2). Primary tumors (T) were all CD117+, and mainly gastric or intestinal (64 & 45 pts), with median size 10 (2-40) cm, CD34+ (82 pts), mitoses/50 HPF ≤ 5 (n = 36), or > 5 (n = 81). Genotype was documented in 82 (58%) pts with 73 (89%) KIT mutations (in exons 11,9 and 12 of 69, 3, and 1 pts respectively) and 9 WT KIT. 129 (91%) T were resected, 124 upfront, 5 post IM, with R0/R1/R2 resections in 61, 11, and 10 pts. Mets were mainly hepatic or peritoneal (78 & 51 respectively). 1st line TKI was given to 139 pts: 130 received IM; 88 (63%) within a clinical trial (CT), 41 (29%) had mets resection. Second, 3d and 4th line TKI were given to 81, 51 and 37 pts respectively, comprising 27, 7 and 10 from CT. Median number of TKIs was 2 (0-7), but 60 (44%) pts received only 1st line with no GIST progression within or after 10 yrs. 2 pts never received TKI but had mets resection. After median FU of 14.3 yrs (10-34.5), 104 remain alive, 37 died. Mean and Median OS from initial dx are 24 yrs (CI95% 21.6-27) and 20,8 yrs. Median PFS on TKIs are 127, 29, 21 and 22 mos on 1st, 2d, 3d and 4th line of TKI. In univariate analysis no factor is significantly associated with OS, but T size (≤ 10 vs > 10 cm) and oligometastatic disease (≤5 vs > 5 mets) are borderline significant (p = 0.056 and 0.07), and good PS (ECOG ≤ 1) at 2dline TKI initiation is associated with better PFS (p = 0.03). Conclusions: This large series of long-term ( > 10 yrs) survivors of metastatic GIST shows a high proportion of mets resection and a longer duration of PFS for TKI at any line. In this selected population, no prognostic factor is associated with long OS.

Outcome of 212 malignant phyllod tumor patients: A retrospective study from the French Sarcoma Group (GSF-GETO)

11055

Background: The optimal management of malignant phyllod tumors (MPT) is poorly documented. Objective:To study the characteristics and outcome of MPT patients (pts). Methods: Retrospective study from the nation-wide French sarcoma network (NetSarc) from 2000 to 2016. Inclusion criteria was central pathological review of MPT. End-points were local recurrence-free survival (LRFS), metastasis-free survival (MFS), and overall survival (OS). Results: 212 pts, from 13 centers, were included. Median age was 52.8 years (range: 16.8 - 90.5). All localized MPT pts (96.7%) underwent surgery with 41.4% of mastectomy. The median size was 5.8 cm (range: 1.5 - 30). R1/R2 resection was achieved in 40.1% pts (26.9% 1-2 mm margin, 12.2% 3-7 mm, 20.3% ≥8 mm), with 44.8% of second surgery (SS) for a final mastectomy rate of 72.6%. Presurgical biopsy was performed in 86.3% and associated with R0 resection ( p=0.044) and better LRFS ( p=0.012). Median follow-up was 4.1 years (range 0-14.8) and revealed 34 (16.6%), 48 (22.9%), 44 (20.8%) events for LRFS, MFS and OS, respectively. The 2-year OS rate was 89%. Prognostic factors found in multivariate analysis are presented in Table 1. Wider margins (≥8mm) were not associated with better outcomes. Adjuvant radiotherapy and chemotherapy were performed in 43.6% and 13.3% respectively and associated with longer LRFS, not significant in multivariate analysis. Conclusions: Mastectomy is associated with better local control, but not with MFS and OS. Age, tumor necrosis and metastatic disease are associated with poor prognosis in MPT pts. Our study suggests that margins of 3 mm are necessary and sufficient for the surgical management of MPT and emphasizes the importance of SS to obtain clear margins. [Table: see text]

Weekly paclitaxel (WP) +/- bevacizumab (B) in angiosarcoma (AS) patients (pts): Analysis of prognostic/predictive factors from a randomized phase 2 trial

11024

Background: WP is an active regimen for treatment of AS pts (Ray-Coquard JCO 2015). We report here the correlative analysis conducted during a phase 2 trial assessing WP +/- B. Methods: Circulating pro/anti-angiogenic factors (FGF, PlGF, SCF, Selectin, thrombospondin, VEGF, VEGF-C) were collected at D1 and D8. Prognostic value for PFS was assessed using Cox model (biomarkers as continuous variables). We attempt to identify subgroups of pts benefiting from adding B using interaction tests (predictive factors). Results: Among the 51 pts enrolled in this trial, 45 were analyzable: 20 in Arm A (WP without B) and 25 in Arm B (with B). Median PFS was 5.5 and 6.1 months, respectively (p = 0.84). Samples were collected in 45 pts at D1 and 42 pts at D1 and 8. Baseline biomarkers were similar in both arms (excluding Selectin, significantly lower in arm A: median of 25 vs. 35 ng/mL, p = 0.03). In arm A, there was no significant difference between values at D1 and D8. In arm B, there were a significant decrease in VEGF (from a median of 0.49 to 0.08 ng/mL; p < 0.01) and selectin (from a median of 35.3 to 31.7 ng/mL; p < 0.01), and a significant increase in PlGF (from a median of 16.1 to 30.0 pg/mL; p < 0.01). In univariate analysis, factors associated with PFS were: de novo vs. radiation-induced AS (HR = 2.39 (p < 0.01), visceral vs. superficial AS (HR = 2.04; p < 0.03), VEGF-C at D1 (HR = 0.77; p < 0.03), FGF at D8 (HR = 1.17; p < 0.01), difference in FGF D8-D1 (HR = 1.24; p < 0.01), and PlGF value at D1 (HR = 1.02; p < 0.05). In multivariate analysis, factors associated with PFS were: de novo AS (HR = 2.39; p = 0.03), VEGF-C at D1 (HR = 0.73; p < 0.02) and FGF difference between D8 and D1 (HR = 1.16; p < 0.02). None of these factors were associated with benefit of adding B. Conclusions: Baseline VEGF-C levels and change in FGF were independent prognostic factors in pts with or without B. Addition of B significantly decreased the level of circulating VEGF and selectin and increased the level of circulating PlGF in AS patients. We did not identify subgroup of pts benefiting from adding of B to WP. Clinical trial information: NCT01303497.

Combination of pembrolizumab and metronomic cyclophosphamide in patients with advanced sarcomas and GIST: A French Sarcoma Group phase II trial

11053

Background: There is a good rationale for immunotherapy in sarcoma. We report results of the first open-label multicentre phase 2 study assessing the anti-PD-1 antibody pembrolizumab in combination with metronomic cyclophosphamide (CP) in patients (pts) with advanced soft tissue sarcomas (STS) and gastro-intestinal stromal tumor (GIST). Methods: This trial included 4 cohorts of pts with advanced STS: leiomyosarcoma (LMS), undifferentiated pleomorphic sarcoma (UPS), other sarcomas (Others), and GIST. All pts received CP 50 mg BID one week on, one week off, and pembrolizumab 200mg IV q21 days. The primary endpoint encompassed non-progression and objective response at 6 months per RECIST evaluation criteria v1.1 for LMS, UPS, and Others, and 6-month non-progression for GIST. Correlative studies of immune biomarkers were planned on pt’s tumor and plasma samples. Results: Between June 2015 and July 2016, 57 pts were included, and 50 were assessable for efficacy. Three pts experienced tumor shrinkage resulting in a partial response (PR) in one of them. The 6-month non-progression rate was 0%, 0%, 14.3% (95%CI 1.8-42.8), and 11.1% (95%CI 2.8-48.3) in LMS, UPS, Others, and GIST respectively. The most frequent adverse events were grade 1 or 2 fatigue, diarrhea, anemia. The only pt who experienced PR was the only one with a PD-L1-positive staining in more than 10% of immune cells on archived tumor sample. A strong macrophage infiltration was observed in tumor samples, and these macrophages largely expressed the inhibitory enzyme Indoleamine-2,3-dioxygenase-1 (IDO1). Moreover, a significant increase of the kynurenine/tryptophane ratio was observed in pts plasma samples during study treatment (p =0.0007). Conclusions: PD-1 inhibition has limited activity in advanced STS and GIST. This primary resistance may be explained by the low percent of PD-L1 positivity in these tumors, and an immune-suppressive tumor microenvironment resulting from macrophage infiltration and IDO1 pathway activation. Further strategies assessing drugs such as CSF1-R inhibitors and/or IDO inhibitors combined with anti-PD-1/PD-L1 in selected sarcoma subtypes are warranted. Clinical trial information: NCT02406781.

Post-cross-over activity of regorafenib (RE) in soft tissue sarcoma: Analysis from the REGOSARC trial

11052

Background: Based on the placebo (PBO) controlled phase 2 trial (Mir, Lancet Oncol 2016), RE has shown to be an active drug in patients (pts) with leiomyosarcoma (LMS), synovial sarcoma (SS) and other non-adipocytic sarcoma (OTH), but not in liposarcoma. Pts initially allocated to PBO were allowed to cross-over to RE after progression. We here report the activity of RE after cross-over. Methods: From July 2013 to Dec 2014, 138 pts were enrolled in the non-adipocytic sarcoma cohorts (LMS, SS & OTH). After update in Dec 2016, median follow-up was 32 mo (vs 17 mo in the initial publication). Benefit of RE vs PBO in terms of progression-free survival (PFS) and overall survival (OS) from randomization was estimated by hazard ratio (HR) in Cox models. In the PBO arm, intra-patient benefit of RE after cross-over was evaluated by the growth modulation index (GMI), where PFS1=PFS with PBO before cross-over, and PFS2=PFS with RE after cross-over. The impact of timing of RE allocation (delayed after cross-over, vs early at study entry) was evaluated by comparing PFS after cross-over in PBO arm to PFS after randomization in RE arm. Results: As detailed in the table, major PFS benefit of RE vs PBO allocated by randomization was confirmed with long follow-up (HR=0.50 [95%CI 0.35-0.71] p<.0001). However, this translates into a smaller and non-significant OS benefit (HR=0.78 [0.54-1.12] p=.18). This finding may partially be explained by the fact that 55 of the 68 pts who progressed in the PBO arm (81%) could receive RE after progression and benefit from RE: 56% of them had a GMI greater than 1.3. Delayed start of RE was associated with a non-significantly shorter PFS compared to earlier treatment (HR=1.21, [0.84-1.73] p=.30). Conclusions: Efficacy of RE vs PBO is confirmed with longer follow-up in non-adipocytic sarcoma. PFS of pts receiving RE after cross-over is not significantly shorter than that of pts initially randomized to receive RE. Clinical trial information: NCT01900743. [Table: see text]

Antiangiogenic effects in patients with progressive desmoplastic small round cell tumor: data from the French national registry dedicated to the use of off-labeled targeted therapy in sarcoma (OUTC's)

BACKGROUND

Desmoplastic small round cell tumor (DSRCT) is a very rare mesenchymal tumor that mainly affects teenagers and young adults with a mean age at diagnosis around 20-25 years. Although initial management still needs standardization, many centers will use multimodal treatment including intensive chemotherapy, extensive surgical resection followed by radiotherapy. Despite this, prognosis remains very poor and the median overall survival is 25 months. Recurrent disease is mainly treated by chemotherapy. Recently, due to the unmet medical need for recurrent disease, targeted therapies were explored for DSRCT.

METHODS

In this study, we assessed the response rate and progression free survival in nine cases of progressive DSRCT included in the OUTC's registry and treated with antiangiogenics targeted agents (sunitinib, sorafenib and bevacizumab). OUTC's, a French national registry, collects data about the use of off-label targeted therapy in sarcoma.

RESULTS

Eight males and one woman were included, with median age at diagnosis of 27.3 years (range from 9 to 48 years). They received a mean 3 lines (2-5) of treatment before antiangiogenic agent initiation. Six patients received sunitinib, two received sorafenib and one bevacizumab. Median progression free survival was 3.1 months (range 2-5.5 months) and best response observed was 5.5 months stable disease. Most patients had manageable low-grade toxicities, mainly fatigue, abdominal pain and skin toxicity.

CONCLUSIONS

Despite very limited activity of antiangiogenics in our study, prospective collection of cases of these rare tumors together with molecular data should guide therapeutic decision and enhance outcome.

Patterns of care and clinical outcomes in primary oesophageal gastrointestinal stromal tumours (GIST): A retrospective study of the French Sarcoma Group (FSG)

BACKGROUND

Oesophageal GIST (ESOGIST) are very rare tumours requiring special consideration regarding diagnosis, surgical management, and perioperative treatment.

METHODS

A retrospective study was conducted across 9 centres in the French Sarcoma Group (FSG) to characterize all patients in the years 2000-2014.

RESULTS

Seventeen patients (pts) with primary localized ESOGIST were identified, with median age 69 years (36-81) and 11 females. Eight tumours (T) occurred in the lower third of the oesophagus, five in the oesophageal gastric junction, two in the superior third, and two in the middle third. All pts underwent oesophagoscopy and/or endoscopic ultrasound (EUS) and CT scan. Fifteen had EUS guided biopsy. Nine pts received Imatinib (IM) as initial treatment resulting in six PR, three SD. Tumours were resected in nine pts (53%) (7 upfront, 2 after IM); via enucleation in four (44%) [median size 4 cm], oesophagectomy in five (56%) [median size 10 cm]. Resections were R0 in three pts (33%), R1 in six (66%). Eight pts (47%) had no tumour resection, and one patient was never treated. Six pts received adjuvant IM. With a median follow-up of 24 months (7-101), 11 pts are alive (64.7%), five died (29.4%), one was lost to follow-up. Two pts of 4 pts relapsed following enucleation.

CONCLUSIONS

ESOGIST can be reliably identified pre-operatively by EUS-guided biopsy. Surgery for ESOGIST is either enucleation or oesophagectomy depending on tumour size, location, and patient's individual surgical risk. Preoperative IM therapy could improve resectability and should be considered if surgery is contraindicated or would lead to negative impact on the functional status of the patient.

Predictors for malignant tissue (MT) in residual masses (RM) of non-seminomatous germ cell tumors (NSGCT) treated by chemotherapy (CT) before surgery

405

Background: About half of the patients operated for RM after CT for a NSGCT doesn’t benefit from surgery because RM contain only necrosis. We develop and validate a predictive score for identifying MT (teratoma and/or viable cancer cells) after primary CT for disseminated NSGCT. Methods: We have conducted a retrospective study. The development cohort (cohort 1) consists in 193 pts treated with CT and surgery of RM at the Oscar Lambret Cancer Center between 1997 and 2014. The validation cohort (cohort 2) consists in 98 pts treated in 5 other French sites. Size of RM, modification in size after CT, pre- and post-CT AFP levels, pre- and post-CT HCG levels, pre- and post-CT LDH levels were collected. The predictive factors have been first identified using univariate logistic regression analysis and then selected using step-by-step (forward) logistic regression. Discrimination has been assessed using Akaike Information Criterion (AIC) and ROC curve. Results: The rates of MT in the RM were 52% and 68%, in the cohort 1 and 2, respectively. The 1-, 2- and 5-y OS in the development cohort were 99, 97 and 95%, respectively. The 1-, 2 and 5-y relapse-free survival in the development cohort were 96, 92 and 91%, respectively. In univariate analysis, the predictive factors for MT were: size of RM > 15 mm (OR=3.32 [95%-CI: 1.6-6.2], p=0.001), stable RM versus diminution in size of RM (OR=3.0 [1.5-5.9] p=0.001) or increase in size versus diminution in size of RM (OR=8.6 [1.7-41.9] p=0.008) and pre-CT AFP level > ULN (OR=2.9 [1.4-6.3], p=0.006). The multivariate analysis had retained 2 predictors for MT: size of RM and pre-CT AFP level > ULN. The ROC was 0.71 [0.61-0.80] with an AIC=143 in the development cohort, and was 0.59 [IC95% 0.46-0.72] in the validation cohort. The model showed adequate calibration with a Hosmer-Lemeshow test p=0.69. Conclusions: Surgery of RM is part of standard of care of disseminated NSGCT. However, this surgery is morbid and at the end about 50% of pts are free of MT. We have developed and validated a predictive score for identifying pts benefiting of surgery.

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

BACKGROUND

Gastrointestinal stromal tumours (GIST) are the most common mesenchymal neoplasms of the gastrointestinal tract. Imatinib followed by sunitinib and regorafenib is the standard sequence of treatment for advanced disease. Pazopanib is effective in soft tissue sarcomas but has never been assessed in advanced GIST in a randomised trial. We aimed to assess the efficacy and safety of pazopanib in patients with previously treated advanced GIST.

METHODS

In this randomised, open-label phase 2 study, we enrolled adults (aged ≥18 years) with advanced GIST resistant to imatinib and sunitinib from 12 comprehensive cancer centres or university hospitals in France and randomly assigned them 1:1 using an interactive web-based centralised platform to 800 mg oral pazopanib once daily in 4-week cycles plus best supportive care or best supportive care alone. Randomisation was stratified by the number of previous treatment regimens (2 vs ≥3); no-one was masked to treatment group allocation. Upon disease progression, patients in the best supportive care group were allowed to switch to pazopanib as compassionate treatment. The primary endpoint was investigator-assessed progression-free survival, analysed by intention-to-treat. All randomised participants who received at least one dose of pazopanib were included in the safety analysis. This study is registered with ClinicalTrials.gov, number NCT01323400.

FINDINGS

Between April 12, 2011, and Dec 9, 2013, 81 patients were enrolled and randomly assigned to pazopanib plus best supportive care (n=40) or best supportive care alone (n=41). The median follow-up was 26·4 months (IQR 22·0-37·8) in the pazopanib plus best supportive care group and 28·9 months (22·0-35·2) in the best supportive care group. 4-month investigator-assessed progression-free survival was 45·2% (95% CI 29·1-60·0) in the pazopanib plus best supportive care group versus 17·6% (7·8-30·8) in the best supportive care group (hazard ratio [HR] 0·59, 95% CI 0·37-0·96; p=0·029). Median progression-free survival was 3·4 months (95% CI 2·4-5·6) with pazopanib plus best supportive care and 2·3 months (2·1-3·3) with best supportive care alone (HR 0·59 [0·37-0·96], p=0·03). 36 (88%) of the patients originally assigned to the best supportive care group switched to pazopanib following investigator-assessed disease progression; these patients had a median progression-free survival from pazopanib initiation of 3·5 months (95% CI 2·2-5·2). 55 (72%) of the 76 pazopanib-treated patients had pazopanib-related grade 3 or worse adverse events, the most common of which was hypertension (15 [38%] in the pazopanib plus best supportive care group and 13 [36%] in the best supportive care group). 20 (26%) patients had pazopanib-related serious adverse events (14 [35%] in the pazopanib plus best supportive care group and six [17%] in the best supportive care group), including pulmonary embolism in eight (9%) patients (five [13%] in the pazopanib plus best supportive care group and three [7%] in the best supportive care group). Three pazopanib-related deaths occurred (two pulmonary embolisms [one in each group] and one hepatic cytolysis [in the best supportive care group]). Three adverse event-related but not pazopanib-related deaths occurred in the best supportive care group after switch to pazopanib; these deaths were from hyperammonaemic encephalopathy, pneumopathy, and respiratory failure.

INTERPRETATION

Pazopanib plus best supportive care improves progression-free survival compared with best supportive care alone in patients with advanced GIST resistant to imatinib and sunitinib, with a toxicity profile similar to that reported for other sarcomas. This trial provides reference outcome data for future studies of targeted inhibitors in the third-line setting for these patients.

FUNDING

GlaxoSmithKline, French National Cancer Institute, EuroSARC (FP7-278742), Centre Léon Bérard.

Relationship between imatinib trough concentration and outcomes in the treatment of advanced gastrointestinal stromal tumours in a real-life setting

BACKGROUND

Imatinib has dramatically improved the prognosis of advanced gastrointestinal stromal tumours (GISTs). Clinical trial data showed that patients with trough imatinib plasma concentrations (Cmin) below 1100 ng/ml (quartile 1) had shorter time to progression, but no threshold has been defined. The main objective of this study was to investigate in advanced GIST whether a Cmin threshold value associated with a longer progression-free survival (PFS) could be specified. This would be the first step leading to therapeutic drug monitoring of imatinib in GIST.

PATIENTS AND METHODS

Advanced GIST patients (n=96) treated with imatinib 400 mg/d (41 stomach, 34 small bowel, and 21 other primary site localisations) were prospectively included in this real-life setting study. Routine plasma level testing imatinib (Cmin) and clinical data of were recorded prospectively.

RESULTS

Small bowel localisation was associated with an increased relative risk of progression of 3.09 versus stomach localisation (p=0.0255). Mean Cmin (±standard deviation) was 868 (±536) ng/ml with 75% inter-individual and 26% intra-patient variability. A Cmin threshold of 760 ng/ml defined by log-rank test was associated with longer PFS for the whole population (p=0.0256) and for both stomach (p=0.043) and small bowel (p=0.049) localisations when analysed separately. Multivariate Cox regression analysis found that Cmin above 760 ng/ml was associated with 65% reduction risk of progression (p=0.0271) in the whole population independently of the anatomical localisation.

CONCLUSION

Concentration of imatinib significantly influences duration of tumour control treatment in GIST patients with a Cmin threshold of 760 ng/ml associated with prolonged PFS in real-life setting.

Management and prognosis of malignant peripheral nerve sheath tumors: The experience of the French Sarcoma Group (GSF-GETO)

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNST) are a rare subtype of soft tissue sarcoma. They can arise in irradiated fields, in patients with type 1 neurofibromatosis (NF1), or sporadically. MPNST exhibit an aggressive behaviour, and their optimal management remains controversial. An unsolved issue is whether NF1-related and sporadic forms of MPNST have a different prognosis, and should be managed differently.

MATERIAL AND METHODS

Adult and paediatric patients with histologically confirmed MPNST treated between 1990 and 2013 in French cancer centres of the GSF/GETO network, were included in this retrospective study.

RESULTS

A total of 353 patients (37% with NF1 and 59% with sporadic tumours) were analysed. Median age at diagnosis was 42 years (range 1-94). The majority of tumours developed in the limbs, were deep-seated and of high grade. Two hundreds and ninety four patients underwent a curative intent surgery. Among them, 60 patients (21%) had neoadjuvant treatment (mainly chemotherapy), and 173 (59%) had adjuvant treatment (mainly radiotherapy). For operated patients, median progression free and overall survival (OS) were 26.3 months and 95.8 months, respectively. In multivariate analysis, poor-prognosis factors for OS were high grade, deep location, locally advanced stage at diagnosis, and macroscopically incomplete resection (R2). NF1 status was not negatively prognostic, except in the recurrence or metastatic setting, where NF1-related MPNST patients treated with palliative chemotherapy showed worse survival than patients with sporadic forms.

CONCLUSION

To our knowledge, our series is the largest study of patients with MPNST reported to date. For operated patients, we showed a worse prognosis for NF1-related MPNST, due to different clinical features at diagnosis, more than NF1 status itself. The French sarcoma group is now conducting correlative analyses on these patients, using the latest molecular tools.