Hensley, Martee L.

11507 Background: Advanced uterine leiomyosarcoma (uLMS) is an aggressive malignancy with poor prognosis. Standard-of-care treatments, including trabectedin (Tb) or pazopanib (P), provide median progression-free survival (PFS) of 3-4 months (mo) and objective response rates (ORR) of ~11%. Homologous recombination deficiency (HRD) in a subset of uLMS supports the use of PARP inhibitors combined with DNA-damaging agents. Preclinical studies demonstrated synergistic activity of olaparib and temozolomide (T+O), and a prior single-arm Phase II study of T+O showed promising efficacy independent of an established biomarker, warranting further investigation in a randomized setting. Methods: Alliance A092104 is a Phase II/III trial evaluating olaparib (200 mg BID) plus temozolomide (75 mg/m² daily, days 1-7, every 21 days) versus investigator’s choice of Tb or P in patients (pts) with advanced uLMS who progressed on ≥2 prior systemic therapies. Stratification factors included ECOG (0-1 vs. 2) and prior lines (2 vs. ≥3). The Phase II (Phase III) primary endpoint was PFS (OS), with a planned suspension of accrual at the end of Phase II. A total of 70 evaluable pts (58 PFS events) were needed to detect an improvement in PFS from 4 vs. 8 mo with power of 90% and 1-sided type I error of 10%, with futility assessed after 29 PFS events. Upon meeting the Phase II futility threshold for PFS, the trial was permanently closed. Data were released from the data and safety monitoring board. Pts continue to be followed for outcomes. Results: 74 pts enrolled (Arm 1: T+O, n = 37; Arm 2: investigator’s choice, n = 37 (Tb, 18; P, 13; 6 pts did not start treatment). The arms were balanced for baseline demographics except race, with the T+O arm having a higher proportion of black/African American (29.7% vs. 16.2%). 21 pts remain on treatment. Hematologic adverse events (AEs) were more frequent in the T+O arm, with Grade 4 neutropenia (19.5%) and thrombocytopenia (8.3%) both managed by dose reductions. Non-hematologic Grade 3 AEs were higher in the investigator’s choice arm (45.2% vs. 13.9%). No Grade 5 AEs were reported. In the first 70 pts, with a median follow-up of 5.9 mo, and 39 total PFS events, the median PFS was 3.2 mo (95% CI: 2.0-NE) for T+O versus 5.6 mo (95% CI: 2.8-NE) for investigator’s choice (HR = 1.00; 95% CI: 0.60-2.17; 1-sided stratified log rank p = 0.50). Within Arm 2, the median PFS for Tb and P were respectively 5.6 (95% CI: 3.1-NE) and 3.8 (95% CI: 1.5-NE) mo. 3 pts in the T+0 arm and 1 patient in the investigator’s choice arm (Tb) had a confirmed partial response. Conclusions: The trial did not meet its primary endpoint of PFS in Phase II. This suggests that a biomarker may be needed before there is further exploration of PARP inhibitor-based regimens in uLMS. Overall survival and analysis of tissue-based biomarkers will be presented. Clinical trial information: NCT05432791 .

TPS11584 Background: Uterine leiomyosarcoma (uLMS) is an aggressive sarcoma subtype with frequent metastatic relapse. Advanced uLMS is treated with gemcitabine/docetaxel or anthracycline-based regimens. After failure of initial chemotherapy, remaining options provide limited benefit (trabectedin: objective response rate (ORR) 11%, median progression-free survival (mPFS) 4.0 months (mo); pazopanib: ORR 11%, mPFS 3.0 mo; dacarbazine: ORR 9%, mPFS 1.5 mo). 18-23% of uLMS harbor deleterious alterations in homologous recombination (HR) DNA repair genes. HR-deficient cancers are unable to effectively repair double-stranded DNA breaks and may be sensitive to poly ADP-ribose polymerase (PARP) inhibitor-based strategies. In preclinical studies, the combination of temozolomide (T), an alkylating agent, and olaparib (O), a PARP inhibitor, markedly suppressed proliferation of uLMS models. Among 22 uLMS patients with median 3 prior lines, O+T demonstrated mPFS 6.9 mo and ORR 27% (Ingham M. et al. ASCO 2021: #11506). In correlative analysis, alterations in HR genes including PALB2 and RAD51B or absence of RAD51 foci formation by a functional assay were observed in patients with prolonged PFS (Bose S. et al. ASCO 2022: #11509). Based on these results, we designed a randomized phase 2/3 study to further evaluate O+T in advanced, pretreated uLMS. Methods: Alliance for Clinical Trials in Oncology A092104 is a randomized, open-label phase 2/3 clinical trial of O+T versus investigator’s choice in advanced uLMS. Eligible patients have ECOG performance status ≤2, progression on ≥ 2 prior treatment lines and measurable disease. Patients are randomized 1:1 to receive T 75 mg/m2 orally daily + O 200 mg orally twice daily on days 1-7 in 21-day cycles (Arm 1) or investigator’s choice of trabectedin 1.5 mg/m2 over 24 hours every 21 days or pazopanib 400-600 mg orally daily (Arm 2). For phase 2, the primary endpoint is PFS. The design evaluates for an improvement in PFS from 4 mo to 8 mo, requires 70 patients, and yields 90% power and 1-sided alpha 0.10. If phase 2 is positive, phase 3 will enroll. For phase 3, the primary endpoint is overall survival (OS). The design evaluates for an improvement in OS from 13 mo to 23 mo, requires 165 patients (including 70 from phase 2) and yields 90% power with 1-sided alpha 0.025. Secondary endpoints include ORR, duration of response, safety and patient-reported outcomes. Archival tissue will be collected and evaluated with a RAD51 foci formation assay. Genomic sequencing results will be obtained where available. The study opened to accrual in 1/2023. Support: U10CA180821, U10CA180882, U24 CA196171; https://acknowledgments.alliancefound.org . Clinical trial information: NCT05633381 .

9514 Background: We sought to compare the response of metastatic STS to G vs. G+D in a phase III study using a novel Bayesian adaptive randomization strategy. Methods: Entry criteria included non-GIST STS diagnosis, age > 10, measurable disease, ≤ 3 prior regimens, normal organ function, and Grade (Gr) ≤ 1 neuropathy. Pts were stratified by histology (leiomyosarcoma [LMS] vs. other), and history of prior pelvic radiation (PPR) or not, yielding 4 diagnostic subgroups. Therapy was G 1200 mg/m2 (over 120 min, d1+d8) or G 900 mg/m2 (over 90 min, d1+d8) and docetaxel (100 mg/m2 d8) q21d; all pts received (peg)-filgrastim starting d9. 25% dose reductions were employed for PPR or toxicity. The primary endpoint was tumor response (CR, PR, or 24+ weeks stable), using a double-blind Bayesian adaptive randomization procedure to incrementally assign more pts to the superior treatment arm, while accounting for possible treatment-subgroup interactions. Although this study is not based on a 1:1 randomized phase III design, enrolling ∼120 pts would show a difference between a response rate (RR) of 10% for G and 30% with G+D with a power of 0.8 and two-sided alpha of 0.05. Results: 122 pts were randomized; 119 pts had evaluable outcomes. Median number of prior regimens was 1; median number of cycles was 4 (range 1–26). 49 pts were adaptively randomized to G and 73 to G+D, indicating superiority of G+D. Of 119 evaluable pts, 27% (G) and 32% (G+D) showed response as defined. The odds of pts with LMS receiving G+D instead of G increased from 1:1 at the start of the study to ∼6:1 at its completion. RR was 10% (G) vs. 16% (G+D) (p=0.15, Fisher exact test). Consistent with the RR outcomes, progression free survival (PFS) was 6.2 m (G+D, K-M 95%CI 3.6–8.8) vs. 2.6 m (G, 95%CI 2.0–3.2). Overall survival (OS) was 18.0 m (G+D, K-M 95%CI 11.7–24.1) vs. 11.2 m (G, 95%CI 6.8–15.5). Pts receiving G+D had a higher rate of discontinuation due to toxicity than those receiving G (p<0.01, log rank). Conclusions: We observed substantial clinical activity in this pre-treated STS population. G+D yields superior PFS and OS to G, but at the price of increased toxicity. Adaptive randomization is an effective method that substantively reduces the number of pts receiving inferior therapy. [Table: see text]

Purpose Fixed-dose rate gemcitabine plus docetaxel achieves objective response in 35% of patients with uterine leiomyosarcoma (uLMS). This study aimed to determine whether the addition of bevacizumab to gemcitabine-docetaxel increases progression-free survival (PFS) in uLMS. Patients and Methods In this phase III, double-blind, placebo-controlled trial, patients with chemotherapy-naive, metastatic, unresectable uLMS were randomly assigned to gemcitabine-docetaxel plus bevacizumab or gemcitabine-docetaxel plus placebo. PFS, overall survival (OS), and objective response rates (ORRs) were compared to determine superiority. Target accrual was 130 patients to detect an increase in median PFS from 4 months (gemcitabine-docetaxel plus placebo) to 6.7 months (gemcitabine-docetaxel plus bevacizumab). Treatment effects on PFS and OS were described by hazard ratios (HRs), median times to event, and 95% CIs. Results In all, 107 patients were accrued: gemcitabine-docetaxel plus placebo (n = 54) and gemcitabine-docetaxel plus bevacizumab (n = 53). Accrual was stopped early for futility. No statistically significant differences in grade 3 to 4 toxicities were observed. Median PFS was 6.2 months for gemcitabine-docetaxel plus placebo versus 4.2 months for gemcitabine-docetaxel plus bevacizumab (HR, 1.12; P = .58). Median OS was 26.9 months for gemcitabine-docetaxel plus placebo and 23.3 months for gemcitabine-docetaxel plus bevacizumab (HR, 1.07; P = .81). Objective responses were observed in 17 (31.5%) of 54 patients randomly assigned to gemcitabine-docetaxel plus placebo and 19 (35.8%) of 53 patients randomly assigned to gemcitabine-docetaxel plus bevacizumab. Mean duration of response was 8.6 months for gemcitabine-docetaxel plus placebo versus 8.8 months for gemcitabine-docetaxel plus bevacizumab. Conclusion The addition of bevacizumab to gemcitabine-docetaxel for first-line treatment of metastatic uLMS failed to improve PFS, OS, or ORR. Gemcitabine-docetaxel remains a standard first-line treatment for uLMS.

Purpose Gemcitabine as a single agent and the combination of gemcitabine and docetaxel have activity in patients with metastatic soft tissue sarcoma. To determine if the addition of docetaxel to gemcitabine improved clinical outcome of patients with metastatic soft tissue sarcomas, we compared a fixed dose rate infusion of gemcitabine versus a lower dose of gemcitabine with docetaxel. Patients and Methods In this open-label phase II clinical trial, the primary end point was tumor response, defined as complete or partial response or stable disease lasting at least 24 weeks. A Bayesian adaptive randomization procedure was used to produce an imbalance in the randomization in favor of the superior treatment, accounting for treatment-subgroup interactions. Results One hundred nineteen of 122 randomly assigned patients had assessable outcomes. The adaptive randomization assigned 73 patients (60%) to gemcitabine-docetaxel and 49 patients (40%) to gemcitabine alone, indicating gemcitabine-docetaxel was superior. The objective Response Evaluation Criteria in Solid Tumors response rates were 16% (gemcitabine-docetaxel) and 8% (gemcitabine). Given the data, the posterior probabilities that gemcitabine-docetaxel was superior for progression-free and overall survival were 0.98 and 0.97, respectively. Median progression-free survival was 6.2 months for gemcitabine-docetaxel and 3.0 months for gemcitabine alone; median overall survival was 17.9 months for gemcitabine-docetaxel and 11.5 months for gemcitabine. The posterior probability that patients receiving gemcitabine-docetaxel had a shorter time to discontinuation for toxicity compared with gemcitabine alone was .999. Conclusion Gemcitabine-docetaxel yielded superior progression-free and overall survival to gemcitabine alone, but with increased toxicity. Adaptive randomization is an effective method to reduce the number of patients receiving inferior therapy.