Citations

11526 Background: There are no FDA-approved treatments for advanced cCS. Chemotherapy provides limited benefit. IDH1/2 mutations (m) occur in 50% of cCS. Both IDHm and wild-type cCS harbor epigenetic dysregulation. In preclinical models, HDAC + DNMT inhibition (i) suppressed growth by inducing apoptosis, reversing the hypermethylated state, and upregulating expression of interferon (IFN) response genes including PDL1(1). This prompted a phase 2 study of HDACi + DNMTi in cCS, which failed to meet the 1° endpoint of ORR. The majority of pts had a best response of stable disease, with a trend towards improved mPFS in IDHm (2). Here we report correlative analysis of NCI 10330. Methods: NCI 10330 is a single-arm, multicenter, phase 2 study of belinostat with SGI-110 or ASTX727 in advanced cCS. All pts were required to have pre- and on-treatment (tx) biopsies (Cycle 2, Day 3-5). Tissue was evaluated with whole exome sequencing (WES) and RNA sequencing (RNAseq). From RNAseq, Tumor Inflammation Signature Scores (TISS) and Tumor Microenvironment functional Gene Set Enrichment Analysis scores (TME GSEA) were calculated as the mean of the log2 normalized counts of 18 signature genes (Danaher et al. J Imm Can 2018) and pre-defined gene sets (3), respectively. Wilcoxon rank sum test was used to analyze TME GSEA between pre- and on-tx samples. Differential expression was significant if |FC| > 1.33, adjusted P <0.01. Results: 19 pts were treated; all received paired biopsies. WES was adequate in 7/19 (37%) pts, with IDHm identified in 3/7 (43%) pts. All pts were MSI-stable, TMB: 1.01-3.57 mut/Mb. RNAseq was adequate in 7/19 (37%) pts at pre-tx and 5/19 (26%) pts at on-tx. TISS ranges trended higher for pre-tx (8.77-10.14) vs on-tx (7.36-9.51) samples. TME GSEA identified significantly enriched tumor immune infiltration (p < 0.05) in pre- vs on-tx samples. Differential analysis identified several gene sets related to inflammation overexpressed in pre-tx samples only, including IFN response. On-tx samples were enriched in myogenesis and coagulation gene sets. Conclusions: This is the first study to describe transcriptomic changes following epigenetic tx in cCS. Contradictory to our preclinical data, HDACi + DNTMi resulted in low expression of inflammation. Prior studies reported that the immune infiltrate of CS at progression is immunosuppressive; higher immune infiltrate is correlated with worse outcomes (4). Loss of inflammation may have implications for disease stability experienced by most pts on NCI 10330. Further analyses are planned to correlate TME (pro- vs anti-inflammatory infiltrates) and outcomes. Analyses are limited by small sample size, highlighting the challenges in collecting adequate CS specimens. 1. Sheikh, Schwartz et al. Mol Cancer Ther 2021. 2. Lacuna et al. ASCO 2023: #11531. 3. Bagaev et al. Can Cell 2021. 4. Richert et al. J Bone Onc 2020. Clinical trial information: NCT04340843 .

11558 Background: Nirogacestat (niro) is a targeted and selective gamma secretase inhibitor approved in the US for adults with progressing desmoid tumors (DT). In the phase 3 DeFi study, niro demonstrated significant improvement vs placebo (pbo) in progression-free survival (PFS: HR, 0.29 [95% CI: 0.15-0.55]; P<.001), objective response rate (ORR: 41% vs 8%; P<.001); and patient-reported outcomes (PROs) of pain, DT-specific symptom burden, physical and role functioning, and overall quality of life ( P≤.01, all). DT are driven by Wnt/β-catenin signaling pathway alterations and about 10-20% of DT are associated with mutations in the APC tumor suppressor gene, which may confer more aggressive DT behavior. Because patients with APC mutations may do worse, regardless of specific therapy, a post hoc analysis was conducted to assess effects of niro in patients with progressing DT and APC mutations. Methods: DeFi was a global, double-blind study that evaluated the efficacy, safety, and tolerability of niro in adults with progressing DT. Patients were randomized to oral niro (150 mg) or pbo twice-daily in continuous 28-day cycles. Descriptive post hoc analyses were conducted to assess effects of niro in patients with somatic and/or germline APC mutations. Results: Among 29 patients in DeFi with APC mutations (niro=13; pbo=16), 19 (66%) were female, 16 (55%) were aged ≤30 years, and 22 (76%) were refractory to prior treatment (with a median of 3 prior lines of treatment). In patients with APC mutation, PFS was improved with niro vs pbo (HR, 0.21 [95% CI: 0.05-1.00], P=.016). Confirmed ORR was 38% (5/13) for niro vs 13% (2/16) for pbo. Niro-treated patients also had greater reduction in median best percent change from baseline compared with pbo-treated patients in target tumor size (-29.5 vs +2.2), volumetric MRI (-71.0 vs +5.4), and T2 hyperintensity (-74.1 vs -21.0). Across all PROs assessed — Brief Pain Inventory, GODDESS DT Symptom Scale and DT Impact Scale, and European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 — patients treated with niro had numerically greater improvement from baseline at cycle 10 than pbo. Analyses were limited due to the small sample size. Adverse events in >50% of niro-treated patients with APC mutation were diarrhea, nausea, rash maculopapular, and fatigue; ovarian toxicity occurred in 9 of 10 of females of reproductive potential (6 resolved, 2 lost to follow-up, 1 ongoing and receiving niro). Conclusions: Improvement in PFS, ORR, tumor imaging characteristics and PROs was observed with niro compared to pbo in patients with DT harboring APC mutations. Efficacy and safety of niro in patients with APC mutations were generally consistent with findings for the overall DeFi population, suggesting that niro can provide clinically meaningful benefit to patients with progressing DT and APCmutations. Clinical trial information: NCT03785964 .

11533 Background: After initial response to first line therapy with imatinib, GISTs commonly progress due to secondary resistance mutations in KIT. As the KIT mutation targeting profiles of bezuclastinib (type I TKI) and sunitinib are distinct, when combined they inhibit a broad spectrum of secondary KIT mutations. Herein we report extended experience of patients treated with 2nd line combination bezuclastinib and sunitinib, including response assessment and safety. Methods: Peak (NCT05208047), a global randomized Phase 3, open-label study, aims to evaluate efficacy and safety of bezuclastinib + sunitinib vs sunitinib in GIST pts with imatinib intolerance or resistance. In Part 1a of the 3-part study, the dose of an optimized formulation of bezuclastinib was escalated in serial cohorts to achieve a target exposure comparable to that achieved at the RP2D established in the prior Phase 1b/2a study. Part 1b evaluated the interaction between bezuclastinib + sunitinib. Key inclusion: adult with locally advanced, metastatic and/or unresectable GIST, ≥1 measurable lesion according to modified RECIST v1.1, and ECOG PS 0 to 2. Part 1 completed enrollment in Apr 2023. Based upon PK and safety, a dose of bezuclastinib 600 mg QD + sunitinib 37.5 mg QD was selected for Part 2. All Part 1 data reported herein are as of Aug 2023; updated safety and efficacy will be presented. Results: Part 1 has completed enrollment with 19 pts in Part 1a and 23 in 1b. In Part 1a, Cohort 1 included 5 pts starting at bezuclastinib 300 mg QD + sunitinib 37.5 mg QD; Cohort 2 included 14 pts at bezuclastinib 600 mg QD + sunitinib 37.5 mg QD. Pt characteristics in Part 1a+1b: median age - 60 yrs (range: 33-77); 81% men; 98% ECOG PS 0-1; 98% metastatic and 2% locally advanced. The majority of TEAEs were low grade and reversible with low rate (38%) of Grade 3+ events. There were limited (24%) dose reductions and infrequent (n=2) discontinuations due to TEAEs. Three pts experienced serious AEs possibly associated with study medications. In pts evaluable for response (received ≥1 cycle of study treatment and had assessments at baseline and post-baseline [n=40]), the objective response rate (ORR) was 20% (6 confirmed PRs, 2 unconfirmed PRs). Data remain immature to estimate median PFS for Part 1 pts. In a subset of pts with prior imatinib only (n=6), the closest approximation for pts enrolling in Part 2, the ORR was 33% (2 confirmed PRs). The majority of 2nd-line pts remain on treatment past 12 months. Conclusions: Data from Peak Part 1 show an encouraging safety and tolerability profile generally consistent with published sunitinib monotherapy experience. ORR in evaluable pts from Part 1 was 20%; ORR in 2nd line pts was 33%. Part 2 of the Peak study is actively enrolling pts globally at the selected dose of bezuclastinib 600 mg QD + sunitinib 37.5 mg QD versus sunitinib 37.5 mg QD. Clinical trial information: NCT05208047 .

11521 Background: Osteosarcomas (OS) comprise the majority of new primary bone tumors in the US and affect a bimodal distribution of young adults (2nd-3rd decades) and older adults >65 yrs. Most large collaborative studies demonstrating the efficacy of HDMTX-containing chemotherapy regimens in OS limited enrollment to patients <40 yrs. Our study aims to fill the gap of reported clinical outcomes in adult OS patients ≥ 40 yrs by describing the feasibility and tolerability of HDMTX in these patients at Mayo Clinic. Methods: We conducted a retrospective chart review of patients ≥18 yrs with OS seen at our institution between 1/1/1980-9/30/2019 and who received ≥1 dose of HDMTX (12 g/m2, max 20 g). Extraosseous OS were excluded. Survival analyses were run for both the entire study population and the subset of patients age ≥40. Patient demographics, disease characteristics, and clinical outcomes were collected. The primary outcome evaluated was 5-year overall survival (5-yr OS). Results: We identified 94 patients whose demographic data are summarized (Table). Twenty-three of 94 (24%) were ≥40 yrs. Both the median number of HDMTX doses received and number of patients who received ≥50% recommended doses were significantly less among patients ≥40 yrs. However, HDMTX-related AKI and median number of hospital days did not differ significantly between the age groups. Among all patients, 5-yr OS was significantly improved (p=0.0025) at 45% (95% CI 35%-58%) for those who received ≥50% doses HDMTX compared to 5-yr OS of 25% (95% CI 12%-53%) for those who did not. Among patients ≥40 yrs, 5-yr OS was significantly improved (p=0.017) at 86% (95% CI 63%-100%) for those who received ≥50% doses HDMTX compared to 5-yr OS of 31% (95% CI 14%-68%) for those who did not. Conclusions: In our cohort, 5-yr OS was superior in those patients who received at least 50% of the planned doses of HDMTX. Older adults were significantly less likely to receive the majority of planned doses, which may be due to clinician bias regarding anticipated toxicity. However, we show that common HDMTX-associated toxicities did not vary significantly by age. If feasible, we recommend referring older patients with osteosarcoma to centers equipped to handle the staffing and supportive care needs of HDMTX administration. [Table: see text]

11508 Background: Trabectedin(T) is a marine-derived minor groove DNA binding compound that alters transcription factor activity. Preclinical data suggests that T suppresses the oncogenic driver of ES, EWS::FLI1. This suppression requires a threshold concentration of T and is potentiated by low doses of Irinotecan(I). Preliminary clinical activity and reversal of the EWS::FLI1 transcriptome was seen in patients (pts) in the phase I portion of SARC037. Here we report the phase II results of T with I at the recommended dose in pts with relapsed/refractory ES. Methods: In this open-label multicenter study, T was given at 1 mg/m2 as a 1-h infusion on day(D)1 with I at 25 mg/m2 intravenously on D2 and D4 of a 21D cycle. Key eligibility criteria were EWS::FLI1 fusion transcript, age ≥6 years, ECOG ≤2, adequate organ function, and willing to have a research biopsy if safely accessible. The primary objective was to determine the objective response rate (ORR) assessed by RECIST v1.1. Secondary objectives were progression-free survival (PFS), duration of response (DOR), and safety. This study used a Simon two-stage design that required 4 or more responses (CR or PR) at the final analysis to establish treatment activity. Results: 18 pts enrolled from 12/2022-12/2023 across 6 sites, 8F/10M, median age 21y (9-43). Pts had a median of 3 (1-7) prior therapy lines, including I in 67% of pts. Of 16 pts evaluable for response at the cutoff date, 5 pts had a PR, and 2 pts had SD. Two pts have evaluations pending and two pts were removed for toxicity before the first evaluation. Median time to response was 2.6 months(m), 6-month PFS was 37.7% (95% CI 18.3%, 77.7%), and all responses were sustained at the time of data cutoff at 10.4+, 7.5+, 5.5+, 5.0+ and 4.6+ m. There were no G5 AEs. Most pts had molecular profiling, translocation testing, as well as ctDNA collection, quantitation, and analysis. A subset of pts had pre- and post-treatment biopsies for RNA sequencing and evaluation of the impact of drug exposure on the EWS::FLI1 transcriptome. Conclusions: T+I exhibited anti-tumor activity in heavily pretreated pts with ES and met its prespecified ORR with 5 PRs in 16 evaluable patients, all of which are ongoing at data cutoff. There were no unexpected safety signals. The combination of T given as a 1h infusion and low-dose I demonstrated meaningful clinical benefit and is worthy of further study in ES pts. Analysis of biological correlates is ongoing. Clinical trial information: NCT04067115 .

11514 Background: The role of immunotherapy remains uncertain in most sarcomas. We recently showed significant antitumor benefit for cabozantinib (C) with N in AS previously treated with a taxane. Since chemotherapy-immunotherapy combinations may synergize, and paclitaxel remains a standard of care option for advanced AS, we hypothesized that P+N would be more effective than P alone. Methods: We report Arm 1 (P+N) and Arm 2 (P) of this open label, multi-arm, phase II study. Pts all had locally advanced/metastatic AS, and no prior taxane (including adjuvant) or checkpoint inhibitor prior to entry. Pts were randomized 1:1 (stratified scalp/face vs other) to receive P 80 mg/m2 on days 1, 8, 15 every 4 weeks (wks), with (Arm 1) or without (Arm 2) N (480 mg intravenously every 4 wks). A pt could remain on study beyond disease progression (PD), after the initial 12 wk evaluation (4 wk confirmatory scan required), but responses were censored at 12 wks. Primary endpoint was progression-free survival (PFS) comparing P+N to P, with an assumed improvement from a median of 4 to 7 months with N added to P (power = 85.3%, alpha = 0.148, and one interim analysis (Wieand rule) for futility planned after 30 events). Secondary endpoints were overall response rate (ORR), adverse events (AEs), overall survival (OS), and pt reported outcomes (PRO). At PD, Arm 2 (P) pts were permitted to receive C+N. Results: 62 evaluable pts (P+N = 30, P = 32 pts) were balanced for age, race, ECOG PS 0 vs. 1, site of disease (including radiation related vs. not), while P+N had more females (60%) and P had more males (63%). Median PFS for P+N was 7.2 mo (5.3-17 mo), and 8.3 mo (4.0-18 mo) for P (hazard ratio (HR) 1.01 (95%CI: 0.55-1.9), p = 0.96). Median PFS for scalp/face was 16 mo (95%CI: 10-NR) for P+N and 8.3 mo (95%CI: 3.7-NR) for P. Median PFS for all others was 5.5 mo (95%CI 4.3-16) for P+N, and 6.0 mo (95%CI 4.1-NR) for P. Median OS was 18 mo (13-NR) in P+N, and 23 mo (15-NR) in P (HR 1.3 (95%CI: 0.63-2.7), p = 0.48). Overall confirmed ORR: P+N = 33% (10/30 pts, with 4 partial responses (PR) and 6 complete responses (CR) with scalp/face ORR = 73%, all others ORR = 11%). Overall ORR for P = 34% (11/32 pts, with 7 PR and 4 CR, with scalp/face ORR = 38%, all others ORR = 26%). Grade 3-4 AEs regardless of attribution occurred in 57% of P+N, and 44% of P, most commonly ( > 10%) fatigue, AST increase, and dyspnea for P+N (n = 3 each), and anemia (n = 4) for P. Conclusions: P alone can be an effective therapy in a subset of pts with AS. The combination of P+N failed to demonstrate improvement in median PFS over P alone, but may show benefit in scalp/face AS. OS trended better with P alone. No new safety signals were observed. The impact of weekly steroid premedication prior to P+N on these outcomes remains to be determined. PRO and exploratory analyses are ongoing. Support: U10CA180821, U10CA180882, U24 CA196171; NCT04339738. https://acknowledgments.alliancefound.org . Clinical trial information: NCT04339738 .

11504 Background: Surgery & radiation therapy (RT) yield high local control rates for soft tissue sarcoma (STS) of the extremity and limb girdle. However, patients (pts) with high-grade stage III STS are at significant risk for developing metastasis. Median survival for pts with metastatic STS is < 2 years. SARC028 (NCT02301039) evaluated the efficacy of pembrolizumab (pembro) for metastatic STS, showing 20% and 8.7% response rates in undifferentiated pleomorphic sarcoma (UPS) and pleomorphic/dedifferentiated liposarcoma (LPS), respectively. We hypothesized that neoadjuvant pembro with concurrent RT followed by surgery and adjuvant pembro for stage III UPS, including myxofibrosarcoma, or LPS would stimulate an anti-tumor immune response to eliminate micrometastatic disease & improve disease-free survival (DFS). SU2C-SARC032 (NCT03092323) is a multi-institutional, international, randomized phase 2 trial evaluating the safety and efficacy of adding pembro to standard of care (SOC) RT & surgery for pts with stage III UPS or LPS. Methods: Pts aged > 12 yo with stage III (FNCLCC grade 2 or 3) UPS or LPS of the extremity and limb girdle were enrolled. Pts were randomized (1:1, stratified by grade) to neoadjuvant RT (50 Gy/25 fx) then surgery (SOC arm) or neoadjuvant pembro and RT then surgery & adjuvant pembro (EXP arm). Pembro was given 200 mg IV Q3 wk for 3 doses (before, during & after RT) & up to 14 adjuvant cycles. The primary endpoint was 2-yr DFS. Secondary endpoints included local recurrence-free survival (LRFS), distant disease-free survival (DDFS), & overall survival (OS). Target enrollment of 126 evaluable patients (max 144 total) provided 80% power (1-sided α = 0.05) to distinguish between a null hypothesis of 50% 2-yr DFS rate & alternative hypothesis of 75% 2-yr DFS rate by log-rank test, with initial analysis at 45 DFS events. Cox models were stratified by grade; primary analysis was a one-sided stratified log-rank test. Results: Between July 2017-November 2023, 143 patients were enrolled, predominantly with UPS (85%) & grade 3 (64%) histology. Median follow-up for alive patients is 24.1 mo. DFS in the EXP arm is significantly higher than the SOC arm (p = 0.023; HR 0.57, 90% CI: 0.35, 0.91). Estimated 2-yr DFS is 53% (90% CI: 43, 66%) for SOC vs 70% (90% CI: 61, 81%) for EXP arm. Currently, there is no statistically significant difference in LRFS (HR 0.55, 95% CI: 0.21, 1.42), DDFS (HR 0.57, 95% CI: 0.32, 1.01), or OS (HR 0.39, 95% CI: 0.14, 1.12). Pts with grade 3 sarcomas had improved DFS with pembro (HR 0.47, 95% CI: 0.25, 0.89), but no difference in DFS was observed in grade 2 tumors (HR 1.21, 95% CI: 0.35, 4.18). The proportion of patients with grade 3+ adverse events was significantly higher in EXP (52%) vs SOC arm (26%) (p = 0.002). Conclusions: Theaddition of neoadjuvant & adjuvant pembro to RT and surgery significantly improves DFS for pts with stage III UPS and LPS of the extremity and limb girdle. Clinical trial information: NCT03092323 .

Background A national survey of general surgery residents revealed significant self-assessed deficits in preparation for independent practice, with only 7.7% of graduating postgraduate year 5 residents (n=1145) reporting self-efficacy for all 10 commonly performed operations surveyed. Objective We sought to understand why this phenomenon occurs. We hypothesized that self-efficacy would be positively correlated with both operative independence and case volume. Methods We compared 3 independent datasets: case information for the same 10 previously surveyed operations for residents graduating in 2020 (dataset 1), operative independence data obtained through the SIMPL OR app, an operative self-assessment tool (dataset 2), and case volume data obtained through the Accreditation Council for Graduate Medical Education National Data Report (dataset 3). Operations were categorized into high, middle (mid), and low self-efficacy tiers; analysis of variance was used to compare operative independence and case volume per tier. Results There were significant differences in self-efficacy between high (87.7%), mid (68.3%), and low (25.4%) tiers ( P =.008 [95% CI 6.2, 32.7] for high vs mid, P <.001 for high vs low [49.1, 75.6], and P <.001 for mid vs low [28.7, 57.1]). The percentage of cases completed with operative independence followed similar trends (high 32.7%, mid 13.8%, low 4.9%, P =.006 [6.4, 31.4] for high vs mid, P <.001 [15.3, 40.3] for high vs low, P =.23 [-4.5, 22.3] for mid vs low). The total volume of cases decreased from high to mid to low self-efficacy tiers (average 91.8 to 20.8 to 11.1) but did not reach statistical significance on post-hoc analysis. Conclusions In this analysis of US surgical residents, operative independence was strongly correlated with self-efficacy.

Dysfunctional endothelium is increasingly recognized as a mechanistic link between cardiovascular risk factors and dementia, including Alzheimer disease. BACE1 (β-site amyloid-β precursor protein-cleaving enzyme 1) is responsible for β-processing of APP (amyloid-β precursor protein), the first step in the production of Aβ (amyloid-β) peptides, major culprits in the pathogenesis of Alzheimer disease. Under pathological conditions, excessive activation of BACE1 exerts detrimental effects on endothelial function by Aβ-dependent and Aβ-independent mechanisms. High local concentration of Aβ in the brain blood vessels is responsible for the loss of key vascular protective functions of endothelial cells. More recent studies recognized significant contribution of Aβ-independent proteolytic activity of endothelial BACE1 to the pathogenesis of endothelial dysfunction. This review critically evaluates existing evidence supporting the concept that excessive activation of BACE1 expressed in the cerebrovascular endothelium impairs key homeostatic functions of the brain blood vessels. This concept has important therapeutic implications. Indeed, improved understanding of the mechanisms of endothelial dysfunction may help in efforts to develop new approaches to the protection and preservation of healthy cerebrovascular function.

Objectives Primary human papillomavirus (HPV) testing by clinician-collection is endorsed by U.S. guideline organizations for cervical cancer screening, but uptake remains low and insights into patients’ understanding are limited. This study aims to primarily address patient awareness of primary HPV screening by clinician-collection and acceptance of primary HPV screening by clinician- and self-collection, and secondarily assess factors associated with awareness and acceptance. Setting Primary care practices affiliated with an academic medical center. Methods A cross-sectional survey study of screening-eligible women aged 30–65 years was conducted to assess awareness and acceptability of primary HPV screening. We analyzed bivariate associations of respondent characteristics with awareness of primary HPV screening by clinician-collection, willingness to have clinician- or self-collected primary HPV testing, and reasons for self-collection preference. Results Respondents (n = 351; response rate = 23.4%) reported cervical cancer screening adherence of 82.8% but awareness of clinician-collected primary HPV as an option was low (18.9%) and only associated with HPV testing with recent screening ( p = 0.003). After reviewing a description of primary HPV screening, willingness for clinician-collected (81.8%) or home self-collected (76.1%) HPV testing was high, if recommended by a provider. Acceptability of clinician-collected HPV testing was associated with higher income ( p = 0.009) and for self-collection was associated with higher income ( p = 0.002) and higher education ( p = 0.02). Higher education was associated with reporting self-collection as easier than clinic-collection ( p = 0.02). Women expected self-collection to be more convenient (94%), less embarrassing (85%), easier (85%), and less painful (81%) than clinician-collection. Conclusions Educational interventions are needed to address low awareness about the current clinician-collected primary HPV screening option and to prepare for anticipated federal licensure of self-collection kits. Informing women about self-collection allows them to recognize benefits which could address screening barriers.