Attia, Steven

The treatment of sarcoma necessitates a collaborative approach, given its rarity and complex management. At a single institution, multidisciplinary teams of specialists determine and execute treatment plans involving surgical, radiation, and medical management. Treatment guidelines for systemic therapies in advanced or nonresectable soft tissue sarcoma have advanced in recent years as new immunotherapies and targeted therapies become available. Collaboration between institutions is necessary to facilitate accrual to clinical trials. Here, we describe the success of the Midwest Sarcoma Trials Partnership (MWSTP) in creating a network encompassing large academic centers and local community sites. We propose a new model utilizing online platforms to expand the reach of clinical expertise for the treatment of advanced soft tissue sarcoma.

Surgical treatment of pelvic sarcoma involving the bone is the standard of care but is associated with several sequelae and reduced functional quality of life (QOL). Treatment with photon and proton radiotherapy is associated with relapse. Carbon ion radiotherapy (CIRT) may reduce both relapse rates and treatment sequelae. The PROSPER study is a tricontinental, nonrandomized, prospective, three-arm, pragmatic trial evaluating treatments of pelvic sarcoma involving the bone. Patients aged at least 15 years are eligible for inclusion. Participants must have an Eastern Cooperative Oncology Group Performance Status score of two or less, newly diagnosed disease, and histopathologic confirmation of pelvic chordoma, chondrosarcoma, osteosarcoma, Ewing sarcoma with bone involvement, rhabdomyosarcoma (RMS) with bone involvement, or non-RMS soft tissue sarcoma with bone involvement. Treatment arms include (1) CIRT (n = 30) delivered in Europe and Asia, (2) surgical treatment with or without adjuvant radiotherapy (n = 30), and (3) proton therapy (n = 30). Arms two and three will be conducted at Mayo Clinic campuses in Arizona, Florida, and Minnesota. The primary end point is to compare the 1-year change in functional QOL between CIRT and surgical treatment. Additional comparisons among the three arms will be made between treatment sequelae, local control, and other QOL measures.

397784 Background: Ripretinib, a switch-control tyrosine kinase inhibitor (TKI), is indicated for patients (pts) with gastrointestinal stromal tumor (GIST) who received prior treatment with ≥3 TKIs, including imatinib. Sunitinib is approved for advanced GIST after imatinib failure. Circulating tumor DNA (ctDNA) analysis may provide insight into the efficacy of these agents in second-line advanced GIST. Here, we present exploratory baseline ctDNA results from INTRIGUE. Methods: INTRIGUE is an open-label, phase 3 study that enrolled adult pts with advanced GIST who progressed on or had intolerance to imatinib (NCT03673501). Randomization was 1:1 to ripretinib 150 mg once daily (QD) or sunitinib 50 mg QD (4 wks on/2 wks off). Baseline peripheral whole blood was analyzed by Guardant360, a 74-gene ctDNA next-generation sequencing (NGS)-based assay. Only KIT mutations are reported here. Results: Of 453 pts in the overall intent-to-treat (ITT) population, 362 (80%) samples were analyzed. ctDNA was detected in 280/362 (77%), with KIT mutations detected in 213/280 (76%). Common resistance mutations were in the KIT activation loop (AL; exons 17/18; 89/213, 42%) and ATP-binding pocket (ATP-BP; exons 13/14; 81/213, 38%). Efficacy in pts with detectable ctDNA in the KIT exon 11 and overall ITT populations was consistent with the primary analysis based on tumor data used for randomization. Pts with KIT exon 11 + 17/18 (−9/13/14) mutations had superior progression-free survival (PFS), objective response rate (ORR), and overall survival (OS) with ripretinib vs sunitinib, whereas pts with exon 11 + 13/14 (−9/17/18) mutations had better PFS, ORR, and OS with sunitinib vs ripretinib (Table). Subgroup safety profiles were consistent with the primary analysis. Conclusions: While KIT ATP-BP mutations predicted clinical benefit from sunitinib vs ripretinib, pts harboring resistance mutations in the KIT AL derived meaningful clinical benefit from ripretinib but not sunitinib. This study demonstrates the value of ctDNA NGS-based sequencing of the complex landscape of KIT mutations to predict the clinical benefit of ripretinib or sunitinib as second-line therapy in pts with advanced GIST. Clinical trial information: NCT03673501 . [Table: see text]

Abstract Purpose: The purpose of this pilot study was to examine the clinical efficacy and safety of serial triamcinolone injections for the treatment of desmoid tumors. Patients and Methods: Nine patients were enrolled into this prospective study and underwent three serial ultrasound-guided triamcinolone injections (120 mg) at 6-week intervals. MRI was compared at baseline and every 6 months, out to 24 months. Safety and tolerability were assessed by clinical evaluation and questionnaires, including the 12-item short form survey (SF-12), visual analog scale (VAS), and desmoid patient-reported outcome (PRO) tool. Results: At 24 months, 8 (88.9%) patients demonstrated a reduction in the volume of their tumor while 1 (11.1%) enlarged. Median tumor volume change was −26.9% (−81.1% to 34.6%; P = 0.055) All 9 tumors remained stable based on World Health Organization criteria, whereas 2 (22.2%) demonstrated partial response based on RECIST. There was a significant decrease in the tumor:muscle postcontrast mean signal intensity ratio at 6 months (P = 0.008) and 24 months (P = 0.004). There was a similar decrease in the tumor:muscle T2 mean signal intensity ratio at 24 months (P = 0.02). We found no difference in the SF-12 and VAS scores, but there were significant improvements in the desmoid PRO. Conclusions: Treatment of desmoid tumors with serial triamcinolone injections appears safe and well tolerated by patients, with a 22% partial response based on RECIST. Further research is needed to confirm our results and determine factors predictive of response.

Abstract Background Regorafenib is one of several FDA‐approved cancer therapies targeting multiple tyrosine kinases. However, there are few subtype‐specific data regarding kinase inhibitor activity in sarcomas. We report results of a single arm, phase II trial of regorafenib in advanced Ewing family sarcomas. Methods Patients with metastatic Ewing family sarcomas (age ≥ 18, ECOG 0–2, good organ function) who had received at least one line of therapy and experienced progression within 6 months of registration were eligible. Prior kinase inhibitors were not allowed. The initial dose of regorafenib was 160 mg oral days 1–21 of a 28‐day cycle. The primary endpoint was estimating progression‐free rate (PFR) at 8 weeks employing RECIST 1.1. Results Thirty patients (median age, 32 years; 33% women [10 patients]; bone primary, 40%; extraskeletal primary, 60%) enrolled at 14 sites. The most common grade 3 or higher toxicities were hypophosphatemia (5 grade 3, 1 grade 4), hypertension (2 grade 3), elevated ALT (2 grade 3). Sixteen patients required dose reductions, most often for hypophosphatemia ( n = 7 reductions in 6 patients); two stopped regorafenib for toxicity. There was one death unrelated to treatment in the 30‐day post‐study period. Median progression‐free survival (PFS) was 14.8 weeks (95% CI 7.3–15.9); PFR at 8 weeks by Kaplan–Meier analysis was 63% (95% CI 46–81%). The RECIST 1.1 response rate was 10%. Median OS was 53 weeks (95% CI 37–106 weeks). Conclusions Regorafenib has modest activity in the Ewing family sarcomas. Toxicity was similar to that seen in approval studies.

PURPOSE Sunitinib, a multitargeted tyrosine kinase inhibitor (TKI), is approved for advanced gastrointestinal stromal tumor (GIST) after imatinib failure. Ripretinib is a switch-control TKI approved for advanced GIST after prior treatment with three or more TKIs, including imatinib. We compared efficacy and safety of ripretinib versus sunitinib in patients with advanced GIST who were previously treated with imatinib (INTRIGUE, ClinicalTrials.gov identifier: NCT03673501 ). PATIENTS AND METHODS Random assignment was 1:1 to once-daily ripretinib 150 mg or once-daily sunitinib 50 mg (4 weeks on/2 weeks off) and stratified by KIT/ platelet-derived growth factor α mutation and imatinib intolerance. The primary end point was progression-free survival (PFS) by independent radiologic review using modified Response Evaluation Criteria in Solid Tumors version 1.1. Secondary end points included objective response rate by independent radiologic review, safety, and patient-reported outcome measures. RESULTS Overall, 453 patients were randomly assigned to ripretinib (intention-to-treat [ITT], n = 226; KIT exon 11 ITT, n = 163) or sunitinib (ITT, n = 227; KIT exon 11 ITT, n = 164). Median PFS for ripretinib and sunitinib ( KIT exon 11 ITT) was 8.3 and 7.0 months, respectively (hazard ratio, 0.88; 95% CI, 0.66 to 1.16; P = .36); median PFS (ITT) was 8.0 and 8.3 months, respectively (hazard ratio, 1.05; 95% CI, 0.82 to 1.33; nominal P = .72). Neither was statistically significant. Objective response rate was higher for ripretinib versus sunitinib in the KIT exon 11 ITT population (23.9% v 14.6%, nominal P = .03). Ripretinib was associated with a more favorable safety profile, fewer grade 3/4 treatment-emergent adverse events (41.3% v 65.6%, nominal P < .0001), and better scores on patient-reported outcome measures of tolerability. CONCLUSION Ripretinib was not superior to sunitinib in terms of PFS. However, meaningful clinical activity, fewer grade 3/4 treatment-emergent adverse events, and improved tolerability were observed with ripretinib.

11562 Background: Afami-cel is an autologous, HLA-A*02-restricted, specific peptide enhanced affinity receptor, T-cell therapy engineered to target MAGE-A4+ solid tumors. The pivotal, 2-cohort, single-arm, Phase 2, SPEARHEAD-1 trial (NCT04044768) with afami-cel met its primary endpoint based on Cohort 1 data. As of September 1, 2021, in 47 patients (pts) with metastatic synovial sarcoma (SyS) or myxoid/round cell liposarcoma (MRCLS), the overall response rate (ORR) per independent review was 34% with encouraging durability (Van Tine, et al. Paper 30: CTOS 2021; Virtual). To identify potential stratification factors for response and assess whether response is a proxy for progression-free survival (PFS), we present pooled analyses using data from the prior Phase 1 trial (NCT03132922) and Cohort 1 of the SPEARHEAD-1 trial. Methods: Eligible pts (16–75 years) were HLA-A*02+ with MAGE-A4+ tumors. Pts received afami-cel after lymphodepleting chemotherapy. The pooled analyses evaluated ORR per RECIST v1.1 by investigator review, stratified by 7 factors, and safety. Results: In the pooled data, 69 pts received afami-cel (2.12–9.99×109 transduced T-cells) and were evaluable for response (Phase 1, n = 18; Phase 2, n = 51); all expressed one eligible HLA-A*02 allele. Median (range) for: age was 42 years (19–76), number of prior lines of therapy was 2 (1–12), and tumor MAGE-A4 H-score was 230 (60–300). Median (range) H-score was higher in SyS (256 [60–300]) than in MRCLS (180 [112–230]). The pooled investigator-assessed ORR was 36.2% (40.7% in SyS; 10.0% in MRCLS). Responses occurred across a wide MAGE-A4 H-score range (134–300). Median (range) duration of response was 52 weeks (8.29–75.14). Response rate was higher in the 59 pts with SyS: with ≤2 vs ≥3 prior lines of therapy (55.2% vs 26.7%), baseline target lesion sum of longest diameters <10cm vs ≥10cm (53.1% vs 25.9%), MAGE-A4 H-score ≥200 vs <200 (46.3% vs 27.8%), without vs with bridging therapy (48.6% vs 29.2%), who were female vs male (46.4% vs 35.5%), aged ≥40 vs <40 years (45.7% vs 33.3%), and from North America vs Europe (42.6% vs 33.3%). In responders vs non-responders with SyS, respectively, median PFS was 58.3 vs 11. 0 weeks (log-rank p-value <0.0001); the probability of being progression-free at 24 weeks was 0.8 vs 0.2. The pooled benefit:risk profile of afami-cel was similar to that in the SPEARHEAD-1 trial (Van Tine, et al. Paper 30: CTOS 2021; Virtual.). Conclusions: We show that baseline tumor burden, prior systemic treatment history, and MAGE-A4 tumor expression levels are potential factors associated with response to afami-cel, although their true predictive value for response status awaits confirmation. Our findings will inform the ongoing clinical development of afami-cel in sarcoma, especially for prognostic studies with PFS or overall survival endpoints. Clinical trial information: NCT04044768, NCT03132922.

11541 Background: Ripretinib (R) is a switch-control tyrosine kinase inhibitor (TKI) indicated for the treatment of patients (pts) with advanced gastrointestinal stromal tumor (GIST) after prior treatment with ≥3 TKIs. In the INTRIGUE study (NCT03673501) there was no significant difference in median PFS (primary endpoint) between R and sunitinib (S). We present exploratory analyses of tolerability data and selected pt reported outcomes (PROs). Methods: Pts were randomized 1:1 to R 150 mg QD or S 50 mg QD 4 weeks on/2 weeks off.Dose modification was allowed for toxicity management. The event of interest was severe or life-threatening (grade ≥3) treatment-related adverse event prior to progression (sTRAE). Days with at least one sTRAE were summed for all treated pts and for pts with ≥1 sTRAE event. PROs were assessed using questions from EORTC QLQ-C30 and Dermatology Life Quality Index (DLQI) at cycle 1 (C1) day 1 (D1), D15, and D29; D1 and D29 of all other cycles; as well as at end of treatment. Differences in PRO scores between baseline and later assessments were calculated across visits. Long-term data will be presented. Results: Pts receiving R (n = 223) versus (vs) S (n = 221) experienced fewer sTRAEs (24% vs 51%, respectively). For all treated pts, the mean time with sTRAEs was 11 days for R and 42 days for S (ratio 0.27, P<0.0001). For pts with ≥1 sTRAE, the mean number of days with a sTRAE was 48 days for R vs 81 days for S (ratio 0.59, p = 0.037). Completion of PRO assessments across the two treatment arms was similar (baseline: R [n = 199], S [n = 199]; C1 D29: R [n = 167], S [n = 177]). Significant differences in self-reported functioning and symptoms were observed by C1 D29. For PROs relating to commonly reported sTRAEs, except constipation, pts in the R arm reported better outcomes than pts in the S arm. Pts in the R arm reported significantly (p<0.05) less decline compared to baseline in pt-reported role function as well as less increase, or improvement, in symptoms of fatigue, appetite loss, diarrhea, nausea/vomiting, and pain vs pts in the S arm. Moderate or severe effect of skin toxicity on pt life, as measured by DLQI in the R arm (n = 165) and in the S arm (n = 175), was observed in 6.6% of pts in the R arm vs 14.8% of pts in the S arm (p = 0.015). Conclusions: In the INTRIGUE study the total number of days with sTRAEs was fewer for pts receiving R vs S. Pts in the R arm also reported significantly less decline in pt-reported role function and less increase in symptoms related to commonly reported sTRAEs, except constipation, vs pts in the S arm. Medical writing provided by Costello Medical. Clinical trial information: NCT03673501.

11509 Background: uLMS is an aggressive sarcoma subtype of smooth muscle origin. Chemotherapy provides limited benefit for advanced disease. 18-25% of uLMS harbor deleterious alterations in homologous recombination (HR) DNA repair genes. uLMS exhibits high levels of replicative stress. These findings prompted a phase 2 study of O+T in pretreated uLMS where O+T demonstrated activity: ORR 27%, mPFS 6.9 mos (Ingham M. et. al. ASCO 2021: #11506) Methods: NCI protocol #10250 is a single-arm, multicenter, phase 2 trial evaluating O+T in advanced uLMS pts with progression on ≥1 prior line. Pre-treatment (Pre) and on-treatment (On) biopsies were collected from 22 pts. In prespecified analysis, we evaluated for a relationship between clinical outcomes and HR gene alterations by whole exome sequencing (WES), SLFN11/MGMT expression by RNAseq, and RAD51 foci formation (functional assay). HRD scores were calculated from WES using scarHRD. Gene expression was evaluated using a Spearman rank-order correlation analysis to identify genes associated with PFS (p < 0.01) and overexpressed in sensitive (S: PFS > 240d) or resistant (R: PFS < 240d) pts. Gene set enrichment analysis (GSEA) was performed (q = FDR-adjusted p value). Pts with available results: WES/RNAseq (16), Pre HRD score (13), Pre RAD51 foci (12). Results: 31% (5/16) pts had a mutation (Mut) or homozygous deletion (Hd) in the HR panel: ATRX Mut (2), ATR Mut, PALB2 Hd, RAD51B Hd. Pts with PALB2 and RAD51B Hd had longest PFS on study. Recurrent alterations also occurred in TP53 (56%) and RB1 (19%). Median HRD score in Pre samples was 51 (range 36-66) and 10/13 had HRD scores ≥ 42. Pre and On SLFN11 and MGMT RNA expression were not correlated with ORR/PFS. 6/13 Pre samples were HR-deficient by the RAD51 foci assay. Of pts with PFS ≥ 200d, 4/6 were HR-deficient. In Pre samples, 81 genes were overexpressed in S pts and 73 in R pts. In On samples, 146 genes were overexpressed in S pts and 127 in R pts. In On samples, GSEA identified the epithelial-mesenchymal transition enriched in S pts (q = 3.38e-7) and cell cycle pathways (E2F targets, G2M checkpoint) in R pts (q = 7.43e-4). Only 2 genes, CXCL10 and PCDH15, were differentially expressed between paired Pre and On samples (both increased in On). Gene expression signatures for replicative stress showed borderline association with worse PFS. Conclusions: Most uLMS tumors exhibit HR defects as measured by HRD scores. A subset of pts with greater benefit from O+T were identified by WES for HR genes and the RAD51 assay. There was no correlation between SLFN11 and MGMT expression and outcomes. GSEA identified pathways differentially expressed in S and R pts in On samples. O+T induced CXCL10 which has been associated with T-cell trafficking to tumors. A randomized phase 3 trial of O+T versus investigator’s choice is planned. These results provide insight into which pts may benefit most from this novel drug combination. Clinical trial information: NCT03880019.

11507 Background: Leiomyosarcoma (LMS) is one of the most common subtypes of soft tissue sarcoma and is associated with high risk of relapse and a poor prognosis for advanced disease. In preclinical LMS models, unesbulin, a microtubule polymerization inhibitor, potentiated the activity of dacarbazine (DTIC) (Jernigan F, et al. Mol Cancer Ther. 2021;20:1846–1857). Here, we report preliminary safety and efficacy results from a Phase 1b dose escalation study evaluating the combination of unesbulin with DTIC in patients with advanced LMS (NCT03761095). Methods: In this single-arm, open-label, Phase 1b clinical trial, patients with advanced LMS received unesbulin orally at 200, 300, or 400 mg twice weekly (BIW) in combination with intravenous DTIC at 1,000 mg/m2 once every 21 days. The primary objectives were to determine the maximum tolerated dose (MTD) and recommended Phase 2 dose (RP2D) of unesbulin in combination with DTIC and to characterize the safety profile of the combination. The time-to-event continual reassessment model (TITE-CRM) was used for dose finding. An expansion cohort with up to 12 additional patients is currently being enrolled. Results: As of the data cutoff on January 6, 2022, 29 LMS patients have been treated. Median prior lines of therapy were 3 (range 1–6). Of 27 evaluable patients, 12 had non-uterine and 15 had uterine LMS. The MTD/RP2D of unesbulin was determined to be 300 mg BIW with DTIC 1,000 mg/m2 every 21 days using the TITE-CRM. At the RP2D, the most common treatment-related adverse events included fatigue, diarrhea, neutropenia, and thrombocytopenia. In the intent-to-treat population, the overall response rate (ORR) was 17.2% (5/29) and the disease control rate (DCR) (DCR = complete response + partial response + stable disease at 12 weeks) was 58.6%. At the 300 mg dose level, the ORR was 19% (4/21) and the DCR was 57.1%. Patients received a median of four cycles (range 1–12). The study is ongoing, with patients continuing to receive treatment. Conclusions: Unesbulin 300 mg BIW in combination with DTIC 1,000 mg/m2 every 21 days was well tolerated and demonstrated promising efficacy in a heavily pre-treated patient population with advanced LMS; these results support further investigation. Updated clinical results will be presented as the data mature. A randomized, placebo-controlled, Phase 2/3 trial is planned. Clinical trial information: NCT03761095.