A randomized, double-blind, phase 2 study of ruxolitinib or placebo in combination with capecitabine in patients with advanced HER2-negative breast cancer and elevated C-reactive protein, a marker of systemic inflammation

Purpose: The Janus-associated kinase (JAK)/signal transducer and activator of transcription pathway is a key regulator of inflammatory signaling, associated with tumorigenesis, cell survival, and progression. This randomized phase 2 trial evaluated the efficacy and safety of the addition of ruxolitinib, a JAK1/JAK2 inhibitor, to capecitabine in patients with HER2-negative advanced breast cancer and high systemic inflammation (modified Glasgow Prognostic Score [mGPS] ≥ 1). Methods: Patients with ≤ 2 prior chemotherapy regimens for advanced or metastatic disease or hormone receptor-positive patients with disease progression on prior hormonal therapies were randomized 1:1 to 21-day cycles of ruxolitinib (n = 76) or placebo (n = 73) plus capecitabine. The primary endpoint was overall survival (OS). Results: Baseline characteristics were well balanced between groups. For ruxolitinib plus capecitabine versus placebo plus capecitabine, median OS was 11.2 months versus 10.9 months (log-rank test P = 0.762); median progression-free survival (PFS) was 4.5 months versus 2.5 months (log-rank test P = 0.151); and overall response rate (ORR) was 28.9% versus 13.7% (Cochran–Mantel–Haenszel test P = 0.024), respectively. A more favorable change in health-related quality of life (HRQoL) was observed with ruxolitinib plus capecitabine versus placebo plus capecitabine. Both regimens were generally tolerable. A higher incidence of grade 3/4 anemia (25.4% vs 5.6%) and a lower incidence of grade 3/4 palmar–plantar erythrodysesthesia (1.4% vs 12.7%) occurred with ruxolitinib plus capecitabine versus placebo plus capecitabine. Conclusions: The addition of ruxolitinib to capecitabine for patients with advanced breast cancer and high systemic inflammation was generally tolerable; ORR was numerically greater, a more favorable change in HRQoL was observed, but neither OS nor PFS was improved compared with placebo plus capecitabine.