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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: A phase I study of the antitumor antibiotic 7-cyanoquinocarcinol, DX-52-1, was conducted in patients with refractory solid malignancies. This study sought to determine the maximum tolerated dose and principal toxicities of this agent and to characterize its pharmacokinetic behavior. Methods: Patients were required to have adequate bone marrow, renal and hepatic function. DX-52-1 was administered by i.v. continuous infusion over a 6-h period each week for four consecutive weeks followed by a 2-week rest period, which constituted one cycle of treatment. Results: Initial dose levels were 3, 6, and 10 mg/m2. An intermediate dose level of 8 mg/m2 was added after acceptable toxicity was observed at the 6 mg/m2 dose level, but dose-limiting toxicities, including life-threatening ones, were seen at the 10 mg/m2 dose level in all three patients. The maximum tolerated dose (MTD) was subsequently determined to be 6 mg/m2. Because a clear pattern of toxicities was not initially evident, a larger than usual number of additional patients (16) were enrolled at the MTD to better distinguish toxicities due to the study drug from those secondary to the patients' underlying malignancies. Even at the MTD, the drug was poorly tolerated, with gastrointestinal toxicities (abdominal pain, nausea, vomiting and increased liver function tests) predominating and dose-limiting. Pharmacokinetic studies revealed that the mean maximum plasma concentration of DX-52-1 in patients evaluated at the MTD (138.8±59.3 ng/ml, n=19) was considerably lower than the concentrations required for cytostatic or cytotoxic activity against sensitive human tumor cell lines in vitro. Further, the weekly dose intensity of the most efficacious treatment schedule identified during in vivo antitumor efficacy studies was 60 times greater than the 6 mg/m2 weekly dose tolerated by cancer patients. None of the 33 patients participating in this study, including the 22 patients evaluated at the MTD, had any response to treatment. Conclusion: Given the poor tolerability, the inability to achieve drug levels necessary to inhibit in vitro or in vivo tumor growth, and the lack of any responses in our study, DX-52-1, as given by this schedule, does not appear to warrant further investigation in phase II studies. [ABSTRACT FROM AUTHOR]

Introduction: A preliminary analysis of our double high-dose chemotherapy with stem cell rescue (HD-SCR) clinical trial for breast cancer, and preclinical cross-resistant studies, suggested that melphalan (M) adversely affected response to subsequent chemotherapy, i.e., that the sequence of alkylating agents (AAs) might affect response. We, therefore, constructed and examined preclinical models to determine whether prior exposure to M, in fact, adversely affected response to other therapy.Purpose: The purpose of the study was to determine whether the sequence of AAs, specifically the prior use of M, adversely affected response to subsequent treatment.Methods: The methods employed were the following: (1) Human tumor cell lines rendered resistant by in vitro sequential exposure to five different AAs were developed. The resistant cell lines were examined for cross-resistance to alkylating and other agents. (2) In vivo studies in the p388 mouse leukemia for resistance and cross-resistance among the AAs. (3) In vivo studies of the effect of sequence of AAs on response in mice bearing EMT6 breast cancer. (4) The double transplant model was developed in the mouse and the sequence of high-dose AAs was studied. (5) Biochemical and reverse transcriptase-polymerase chain reaction (RT-PCR) studies of the various resistant tumor cell lines.Results: (1) The in vitro human tumor cells resistant to M were cross-resistant in 57% of tests to other AAs. In contrast, resistance for other AAs crossed to other agents in only 10 to 20% of tests. (2) The in vivo studies of p388 indicated that resistance to M commonly crossed to other AAs and many non-AAs. (3) The results for the mouse breast cancer (EMT6) studies of the sequence of AAs again indicated that M employed first markedly reduced responsiveness to subsequent treatment, particularly with AAs. (4) The double transplant model: again, M first markedly reduced response to other agents. (5) The in vitro resistant human tumor cell lines, particularly the breast cancer cell line MCF7, were found to contain high concentrations of glutathione S1 transferase gamma, which is consistent with that mechanism being responsible for resistance.Conclusion: The sequence of alkylating agent treatment may substantially influence response. Melphalan, particularly, produces resistance that commonly crosses to the other AAs. Mechanistic studies indicate significant changes in glutathione S1 transferase, a known mechanism for broadly based resistance to AAs. [ABSTRACT FROM AUTHOR]