BACKGROUND Although CDK4/6 inhibitors are an established treatment for hormone receptor–positive, HER2-negative metastatic breast cancers, their benefit in other malignancies remains limited.METHODS We investigated factors associated with clinical outcomes from CDK4/6 inhibitor–based therapy among patients with G1/S phase cell-cycle alterations (CDK4/6 amplifications, CCND1/2/3 amplifications, or CDKN2A/B alterations).RESULTS Overall, 2457 patients with diverse solid tumors that underwent clinical-grade, next-generation sequencing (182–465 genes) and therapy outcome of (non–breast cancer) patients treated with matched CDK4/6 inhibitors were analyzed. G1/S phase cell-cycle alterations occurred in 20.6% (507 of 2457) of patients; 99% of those patients (n = 501) harbored ≥1 characterized co-alteration (median, 4; range, 0–24). In 40 patients with G1/S phase cell-cycle alterations given CDK4/6 inhibitors as part of their regimen, significantly longer median progression-free survival (PFS) was observed when CDK4/6 inhibitor–based therapies matched a larger proportion of tumor alterations, often because CDK4/6 inhibitors were administered together with other drugs that were matched to genomic co-alterations, hence achieving a high matching score (high vs. low [≥50% vs. <50%] matching score, PFS, 6.2 vs. 2.0 months, P < 0.001 [n = 40] [multivariate]) and higher rate of stable disease ≥6 months or an objective response (57% vs. 21%, P = 0.048).CONCLUSION In summary, in cell-cycle–altered cancers, matched CDK4/6 inhibitors, as part of an individualized regimen targeting a majority of genomic alterations, was independently associated with longer PFS.TRIAL REGISTRATION ClinicalTrials.gov NCT02478931.FUNDING Joan and Irwin Jacobs Fund, National Cancer Institute (P30 CA023100, R01 CA226803), and the FDA (R01 FD006334).
Shumei Kato, Ryosuke Okamura, Jacob J. Adashek, Noor Khalid, Suzanna Lee, Van Nguyen, Jason K. Sicklick, Razelle Kurzrock
Characteristics of 507 patients with alterations in the G1/S phase cell-cycle signaling pathway