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Purpose: Preclinical studies support the JAK2–STAT3 signaling pathway as a key driver in CD44+ CD24− "stem-cell-like" breast cancer cells. Ruxolitinib is an orally bioavailable JAK1/2 inhibitor. We aimed to identify the recommended phase 2 dose (RP2D) of ruxolitinib in combination with paclitaxel in patients with HER2-negative metastatic breast cancer (MBC). Methods: Eligible patients had HER2-negative MBC and had received ≤ 3 chemotherapy regimens for advanced disease. Patients received oral ruxolitinib (10–25 mg bid) in a 3 + 3 dose escalation design in combination with weekly paclitaxel 80 mg/m2 in a 3-week cycle. The primary objective was to determine the maximum tolerated dose (MTD) and the RP2D. Results: Nineteen patients received protocol therapy (mean age 52 years). Eight (42%) had triple-negative breast cancer and 11 (58%) had hormone receptor-positive disease; 12 (63%) had visceral disease. Ten (53%) patients had not received prior treatment for advanced disease. Patients received a median number of 5 cycles of combination therapy (range 1–12) and five patients continued single-agent ruxolitinib. The MTD of ruxolitinib was 25 mg bid when combined with paclitaxel, and the RP2D for the combination was 15 mg bid. Thirteen (68%) patients required dose reductions or holds. Most frequent toxicities reported of any grade were neutropenia (50%) and anemia (33%). There were no grade 4/5 toxicities attributed to study drug. Four (21%) patients had PR, 12 (63%) had SD and three (16%) had PD as their best response. Conclusion: The combination of ruxolitinib and weekly paclitaxel was well tolerated with evidence of clinical activity. Further analysis of this combination is ongoing (NCT02041429). Trial registration: NCT02041429. Date of registration: January 22, 2014. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the safety and feasibility of concurrent radiation therapy and paclitaxel-based adjuvant chemotherapy, given either weekly or every 3 weeks, after adjuvant doxorubicin and cyclophosphamide (AC). Methods and Materials: After definitive breast surgery and AC chemotherapy, 40 patients with operable Stage II or III breast cancer received protocol-based treatment with concurrent paclitaxel and radiation therapy. Paclitaxel was evaluated on 2 schedules, with treatment given either weekly × 12 weeks (60 mg/m2), or every 3 weeks × 4 cycles (135–175 mg/m2). Radiation fields and schedules were determined by the patient’s surgery and pathology. The tolerability of concurrent therapy was evaluated in cohorts of 8 patients as a phase I study. Results: Weekly paclitaxel treatment at 60 mg/m2 per week with concurrent radiation led to dose-limiting toxicity in 4 of 16 patients (25%), including 3 who developed pneumonitis (either Grade 2 [1 patient] or Grade 3 [2 patients]) requiring steroids. Efforts to eliminate this toxicity in combination with weekly paclitaxel through treatment scheduling and CT-based radiotherapy simulation were not successful. By contrast, dose-limiting toxicity was not encountered among patients receiving concurrent radiation with paclitaxel given every 3 weeks at 135–175 mg/m2. However, Grade 2 radiation pneumonitis not requiring steroid therapy was seen in 2 of 24 patients (8%) treated in such a fashion. Excessive radiation dermatitis was not observed with either paclitaxel schedule. Conclusions: Concurrent treatment with weekly paclitaxel and radiation therapy is not feasible after adjuvant AC chemotherapy for early-stage breast cancer. Concurrent treatment using a less frequent paclitaxel dosing schedule may be possible, but caution is warranted in light of the apparent possibility of pulmonary injury. [Copyright &y& Elsevier]