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).

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).

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.

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.