Richard Riedel

INTRODUCTION: Soft tissue and bone sarcomas are a heterogeneous group of malignancies, each with a unique biology and clinical course. As our understanding of individual sarcoma subtypes and their molecular landscapes increases, predictive biomarkers are emerging to improve patient selection for chemotherapies, targeted therapies, and immunotherapy approaches. AREAS COVERED: This review highlights predictive biomarkers rooted in molecular mechanisms of sarcoma biology, focusing on cell cycle regulation, DNA damage repair, and immune microenvironment interactions. We review CDK4/6 inhibitor predictive biomarkers, including CDKN2A loss, ATRX status, MDM2 levels, and Rb1 status. We discuss homologous recombination deficiency (HRD) biomarkers that predict vulnerability to DNA damage repair (DDR) pathway inhibitors, such as molecular signatures and functional HRD markers. We describe tertiary lymphoid structures and suppressive myeloid cells in the sarcoma immune microenvironment that may influence immunotherapy efficacy. EXPERT OPINION: While predictive biomarkers are not routinely used in sarcoma clinical practice currently, emerging biomarkers are being developed alongside clinical advancements. Novel therapies and predictive biomarkers will be essential for individualizing future approaches to sarcoma management and improving patient outcomes.

BACKGROUND: Desmoid tumors are rare, locally aggressive, highly recurrent soft-tissue tumors without approved treatments. METHODS: We conducted a phase 3, international, double-blind, randomized, placebo-controlled trial of nirogacestat in adults with progressing desmoid tumors according to the Response Evaluation Criteria in Solid Tumors, version 1.1. Patients were assigned in a 1:1 ratio to receive the oral γ-secretase inhibitor nirogacestat (150 mg) or placebo twice daily. The primary end point was progression-free survival. RESULTS: From May 2019 through August 2020, a total of 70 patients were assigned to receive nirogacestat and 72 to receive placebo. Nirogacestat had a significant progression-free survival benefit over placebo (hazard ratio for disease progression or death, 0.29; 95% confidence interval, 0.15 to 0.55; P<0.001); the likelihood of being event-free at 2 years was 76% with nirogacestat and 44% with placebo. Between-group differences in progression-free survival were consistent across prespecified subgroups. The percentage of patients who had an objective response was significantly higher with nirogacestat than with placebo (41% vs. 8%; P<0.001), with a median time to response of 5.6 months and 11.1 months, respectively; the percentage of patients with a complete response was 7% and 0%, respectively. Significant between-group differences in secondary patient-reported outcomes, including pain, symptom burden, physical or role functioning, and health-related quality of life, were observed (P≤0.01). Frequent adverse events with nirogacestat included diarrhea (in 84% of the patients), nausea (in 54%), fatigue (in 51%), hypophosphatemia (in 42%), and maculopapular rash (in 32%); 95% of adverse events were of grade 1 or 2. Among women of childbearing potential receiving nirogacestat, 27 of 36 (75%) had adverse events consistent with ovarian dysfunction, which resolved in 20 women (74%). CONCLUSIONS: Nirogacestat was associated with significant benefits with respect to progression-free survival, objective response, pain, symptom burden, physical functioning, role functioning, and health-related quality of life in adults with progressing desmoid tumors. Adverse events with nirogacestat were frequent but mostly low grade. (Funded by SpringWorks Therapeutics; DeFi ClinicalTrials.gov number, NCT03785964.).