Dickson, Mark A.

LBA2 Background: Dedifferentiated liposarcoma (DDLS) remains a difficult disease to treat with limited systemic therapy options. Approved drugs offer modest benefit such as trabectedin (median progression-free survival [mPFS] 2.2 months [m]) or eribulin (mPFS 2.0m). The Cyclin-dependent kinase 4 (CDK4) oncogene is ubiquitously amplified in DDLS and is a rational therapeutic target. In single-arm phase 2 studies, treatment with selective CDK4 inhibitors resulted in mPFS 4.2m with palbociclib and mPFS 7.7m with abemaciclib. We hypothesized that treatment with abemaciclib would improve PFS compared to placebo in patients with recurrent or metastatic DDLS. Methods: SARC041 was a phase 3 randomized double-blind study of abemaciclib versus placebo. The study was open at 9 academic medical centers in the USA. Eligible patients (pts) had recurrent or metastatic DDLS (purely well-differentiated liposarcoma excluded), progression of disease by RECIST 1.1 in the 6 months prior to study entry, any number of prior systemic therapies, and adequate organ function and performance status. Pts were stratified by prior lines of therapy (0 vs 1 or more) and randomized 1:1 between abemaciclib 200 mg PO twice a day or matching placebo. Scans were every 6 weeks (every 12 weeks after week 36) and pts with progression of disease on placebo could cross over to open label abemaciclib. The primary endpoint was PFS. The design provided 80% power with two-sided 10% significance level to detect a hazard ratio of 0.6 by log-rank test. Secondary endpoints were overall response rate (ORR), PFS and response rate after crossover, and overall survival (OS). Data cutoff was March 1, 2026. Results: In total, 108 pts were randomized to receive abemaciclib (n = 54) or placebo (n = 54). Demographic/baseline characteristics were generally similar across treatment arms. Abemaciclib demonstrated a statistically significant improvement in PFS at 9.67m vs placebo at 1.52m (hazard ratio [HR] 0.39; 95% confidence interval [CI], 0.25–0.59; p < 0.001). ORR was 9.3% for abemaciclib vs 0% for placebo (p = 0.057). mOS was not reached with abemaciclib vs 25.45m with placebo (HR 0.55; 95% CI, 0.28–1.07; p = 0.077). mPFS after crossover from placebo to abemaciclib was 3.44m (95% CI 2.66, 6.84). ORR after crossover was 4.3% (95% CI 0.53%, 15%). mOS after crossover was 24.03m (95% CI: 11.7, NA). Grade 3 or higher adverse event rates were similar in both arms (p > 0.99). No new safety signals were observed. Conclusions: Abemaciclib demonstrated a statistically significant improvement in PFS vs placebo in pts with dedifferentiated liposarcoma, with an encouraging OS trend. These results support abemaciclib as a new treatment option for dedifferentiated liposarcoma. Clinical trial information: NCT04967521 .

Gemcitabine plus docetaxel is an effective treatment regimen for advanced soft tissue sarcomas (STSs). However, the prognosis for patients remains poor, and thus there is an urgent medical need for novel and effective therapies to improve long-term outcomes. The aim of the ANNOUNCE 2 trial was to explore the addition of olaratumab (O) to gemcitabine (G) and docetaxel (D) for advanced STS. Adults with unresectable locally advanced/metastatic STS, ≤2 prior lines of systemic therapy, and ECOG PS 0–1 were eligible. In Phase 2, patients were randomized 1:1 from two cohorts (O-naïve and O-pretreated) to 21-day cycles of olaratumab (20 mg/kg Cycle 1 and 15 mg/kg other cycles, Days 1 and 8), gemcitabine (900 mg/m2, Days 1 and 8), and docetaxel (75 mg/m2, Day 8). The primary objective was overall survival (OS) in the O-naïve population (α level = 0.20). Secondary endpoints included OS (O-pretreated), other efficacy parameters, patient-reported outcomes, safety, pharmacokinetics, and immunogenicity. A total of 167 and 89 patients were enrolled in the O-naïve and O-pretreated cohorts, respectively. Baseline patient characteristics were well balanced. No statistically significant difference in OS was observed between the investigational vs. control arm for either cohort (O-naïve cohort: HR = 0.95 (95% CI: 0.64−1.40), p = 0.78, median OS, 16.8 vs. 18.0 months; O-pretreated cohort: HR = 0.67 (95% CI: 0.39−1.16), p = 0.15, median OS 19.8 vs. 17.3 months). Safety was manageable across treatment arms. There was no statistically significant difference in the primary endpoint of OS between the two arms in the O-naïve population, and therefore based on hierarchical evaluation no other outcomes in this study can be considered statistically significant. No new safety signals were observed.

TPS11587 Background: Recurrent or metastatic dedifferentiated liposarcoma (DDLS) remains a difficult disease to treat. Available agents such as doxorubicin, eribulin, trabectedin, ifosfamide, dacarbazine, or gemcitabine-based regimens are associated with low response rates and only modest improvements in progression free or overall survival. The oncogene CDK4 is ubiquitously amplified in this disease and represents a rational therapeutic target. In single-arm phase 2 studies, treatment with selective CDK4 inhibitors resulted in clinical benefit (12-week progression-free survival (PFS) of 57% with palbociclib and 74% with abemaciclib). We hypothesize that treatment with abemaciclib will improve PFS compared to placebo in patients with recurrent or metastatic DDLS. Methods: This is a phase 3 randomized double-blind study of abemaciclib versus placebo. Eligible patients have recurrent or metastatic dedifferentiated liposarcoma (purely well-differentiated liposarcoma excluded), progression of disease by RECIST 1.1 in the 6 months prior to study entry, any number of prior systemic therapies, and adequate organ function and performance status. Patients are stratified by number of prior lines of therapy (0 vs 1 or more) and randomized 1:1 between abemaciclib 200 mg PO twice a day and matching placebo. Patients are followed with scans every 6 weeks (every 12w after 36w) and those with progression of disease on placebo may cross over to open label abemaciclib. The primary endpoint is PFS. Target enrollment is 108 evaluable patients which provides 80% power with two-sided 10% significance level to detect a hazard ratio of 0.6. Secondary endpoints include response rate, PFS and response rate after crossover, and overall survival. Archival tissue will be collected to explore potential biomarkers. As of Feb 1, 2023, 43 patients have been accrued at 9 participating centers. Clinical trial information: NCT04967521 .

PURPOSE Antitumor activity in preclinical models and a phase I study of patients with dedifferentiated liposarcoma (DD-LPS) was observed with selinexor. We evaluated the clinical benefit of selinexor in patients with previously treated DD-LPS whose sarcoma progressed on approved agents. METHODS SEAL was a phase II-III, multicenter, randomized, double-blind, placebo-controlled study. Patients age 12 years or older with advanced DD-LPS who had received two-five lines of therapy were randomly assigned (2:1) to selinexor (60 mg) or placebo twice weekly in 6-week cycles (crossover permitted). The primary end point was progression-free survival (PFS). Patients who received at least one dose of study treatment were included for safety analysis (ClinicalTrials.gov identifier: NCT02606461 ). RESULTS Two hundred eighty-five patients were enrolled (selinexor, n = 188; placebo, n = 97). PFS was significantly longer with selinexor versus placebo: hazard ratio (HR) 0.70 (95% CI, 0.52 to 0.95; one-sided P = .011; medians 2.8 v 2.1 months), as was time to next treatment: HR 0.50 (95% CI, 0.37 to 0.66; one-sided P < .0001; medians 5.8 v 3.2 months). With crossover, no difference was observed in overall survival. The most common treatment-emergent adverse events of any grade versus grade 3 or 4 with selinexor were nausea (151 [80.7%] v 11 [5.9]), decreased appetite (113 [60.4%] v 14 [7.5%]), and fatigue (96 [51.3%] v 12 [6.4%]). Four (2.1%) and three (3.1%) patients died in the selinexor and placebo arms, respectively. Exploratory RNA sequencing analysis identified that the absence of CALB1 expression was associated with longer PFS with selinexor compared with placebo (median 6.9 v 2.2 months; HR, 0.19; P = .001). CONCLUSION Patients with advanced, refractory DD-LPS showed improved PFS and time to next treatment with selinexor compared with placebo. Supportive care and dose reductions mitigated side effects of selinexor. Prospective validation of CALB1 expression as a predictive biomarker for selinexor in DD-LPS is warranted.

11517 Background: Doxorubicin (doxo) remains standard first-line therapy for advanced STS. Doxo in combination with olaratumab (O) demonstrated superior clinical activity compared to doxo alone in a Ph 2 trial (NCT01185964), although this was not confirmed in the subsequent Ph 3 trial (NCT02451943). Gemcitabine (G) plus docetaxel (D) is a second line therapy for advanced STS. Here, we report a concurrent Ph 2 study that explored a second-line addition of O to G and D for advanced STS (ANNOUNCE 2 NCT02659020). Methods: Adult patients (pts) with unresectable locally advanced or metastatic STS, ≤ 2 prior lines of systemic therapy, and ECOG PS 0-1 were eligible. Pts were enrolled from 2 cohorts: O-naïve and O-pretreated. In both cohorts, pts were randomized 1:1 to either O, G plus D or placebo (PBO), G plus D. Pts received 21-day cycles of O (20 mg/ kg cycle 1 and 15 mg/kg other cycles, day (d) 1 and d8), G (900 mg/m2, d1 and d8) and D (75 mg/m2, d8). Pts continued treatment until progression, toxicity, or withdrawal. Randomization was stratified by histology (leiomyosarcoma [LMS] vs non-LMS), prior systemic therapy, ECOG PS, and prior pelvic radiation. The primary objective was overall survival (OS) in the O-naïve population using an alpha level of 0.20. Secondary endpoints included OS (O-pretreated) and other efficacy parameters, as well as safety and pharmacokinetics (PK). Results: 167 pts were enrolled in the O-naïve cohort and 89 pts in the O-pretreated cohort. Baseline patient characteristics were well balanced. OS for O-naïve pts was 16.8 vs 18.0 months (m) (hazard ratio [HR] = 0.95, 95% CI: 0.64-1.40; p = 0.78) for the investigational vs control arm, respectively. Other efficacy outcomes are presented in the table. Safety was manageable across treatment arms. PK parameter estimates for O were consistent with previous studies. Conclusions: There was no statistically significant difference in OS between the two arms in the O-naïve population. However, while not statistically significant, the combination of O, G and D demonstrated favorable OS in the O-pretreated cohort, and PFS and objective response rate (ORR) in both cohorts. For O-naïve pts, a clinically meaningful progression-free survival (PFS) improvement was observed. Further investigations in specific histological subtypes are ongoing. Clinical trial information: NCT02659020. [Table: see text]

11562 Background: Soft tissue sarcoma (STS) is a heterogeneous malignancy of connective tissue. Although mTOR is implicated in STS pathogenesis, clinical activity from mTORC1 inhibitors is modest. M, a potent selective mTORC1/mTORC2 inhibitor, was more effective in STS preclinical models than inhibitors of mTORC1, IGF1R and mTORC1+IGF1R, owing to more complete suppression of PI3K/AKT/mTOR and abrogation of feedback AKT activation. P, an oral multikinase inhibitor, is approved for non-adipocytic STS and often used after progression (PD) on chemotherapy. In phase 1, the RP2D of M was 30 mg weekly. A091304 was to evaluate M as a novel targeted therapy for STS. Methods: In A091304, pts were randomized 1:1 to M 30 mg weekly or P 800 mg daily. Eligibility required Eastern Cooperative Oncology Group PS ≤ 1, progression on ≥ 1 prior chemotherapy and specific STS subtypes (cohort 1: UPS; 2: LMS; 3: MPNST, SS). Crossover to M was allowed after PD on P. 1° endpoint was progression-free survival (PFS). Assuming median PFS of P was 4.6 months (mo), 98 pts yielded 80% power to detect a hazard ratio of 0.66 favoring M [1-sided test, alpha = 0.15] and including 1 planned futility analysis. 2° endpoints were response rate, clinical benefit rate (CBR) at 4 mo and safety. After 4 of the first 12 pts randomized to P experienced ≥ grade (gr) 3 toxicity, the study was amended to begin at P 400 mg, allowing titration to 800 per investigator discretion. Results: After protocol amendment, 114 pt underwent randomization (M: 56, P: 58), and 111 initiated treatment. Median PFS was 2 mo for M and 2.1 mo for P (HR = 1.47; 1-sided 85% upper confidence boundary = 1.85), with 2 partial responses in each arm. CBR was 5.4% for M and 13.8% for P. Median OS was 10.7 mo for M and 13.9 mo for P (HR = 1.41; 95% CI 0.80-2.49). 26/43 pt with PD on P crossed over to M. Median PFS after crossover was 1.8 mo (95% CI 1.5-3.5). Gr 3 drug-related adverse events (AEs) occurred in 36% on M and 41% on P; gr 4 toxicity was rare. AEs were consistent with known effects of M and P. Conclusions: P at 400 mg daily (allowing escalation to 800 mg per investigator discretion) demonstrated a shorter PFS as compared prior randomized studies with P. Despite this, M failed to demonstrate superior clinical activity as compared to P at the interim analysis. Further work will examine activity within histology-specific cohorts and evaluate available tissue samples for evidence of pharmacodynamic activity. Support: U10CA180821, U10CA180882, U10CA180888, UG1CA233324 (SWOG); https://acknowledgments.alliancefound.org . Clinical trial information: NCT02601209 .

CRA9003 The full, final text of this abstract will be available at abstract.asco.org at 7:30 AM (EDT) on Saturday, June, 1, 2013, and in the Annual Meeting Proceedings online supplement to the June 20, 2013, issue of Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Saturday edition of ASCO Daily News.

TPS10594 Background: Approximately 13,000 cases of soft tissue and bone are diagnosed annually in the US. Despite primary surgery many patients develop recurrent disease. Response rates to chemotherapy are low and new agents are needed. Gene array studies have shown Aurora Kinase A (AURKA) commonly overexpressed. Inhibition of AURKA by shRNA or by a specific AURKA inhibitor blocks in vitro proliferation of multiple sarcoma subtypes. MLN8237 (alisertib) is a novel and oral, ATP-competitive, selective small-molecule inhibitor of AURKA. We hypothesize that alisertib will be an effective treatment for advanced/metastatic sarcoma. Methods: This CTEP-sponsored, investigator-initiated, multi-center phase II study uses alisertib in patients with advanced/metastatic sarcoma and is conducted through the Alliance for Clinical Trials in Oncology (Alliance A091102). Patients must have adequate performance status, organ function, and measurable disease (RECIST v1.1). Patients are enrolled in one of five cohorts, depending on histology: 1) liposarcoma, 2) leiomyosarcoma, 3) undifferentiated sarcoma, 4) malignant peripheral nerve sheath tumor, or 5) other. Patients are treated with alisertib 50mg PO BID d1-d7 every 21 days until either progressive disease or unacceptable toxicity. The primary endpoint is objective overall response rate (ORR). Secondary endpoints include progression-free survival (PFS) and overall survival (OS). Translational objectives include correlation of ORR, PFS and OS with baseline and post-treatment markers of AURKA inhibition in tumor biopsies and baseline and post-treatment [F-18] FLT-PET scans. A Simon two-stage design is used for each of the 5 cohorts and one confirmed response in the first 9 patients expands enrollment in that cohort to 24. Enrollment began in December 2012. As of January 2013, 14 pts have been enrolled. Funded by the Alliance for Clinical Trials in Oncology. Clinical trial information: NCT01653028.