Phase II trial of tipifarnib plus neoadjuvant doxorubicin-cyclophosphamide in patients with clinical stage IIB-IIIC breast cancer.

PURPOSE: Tipifarnib is a farnesyl transferase (FTase) inhibitor that has activity in metastatic breast cancer and enhances the efficacy of cytotoxic agents in preclinical models. We evaluated the biological effects of tipifarnib in primary breast cancers in vivo, whether adding tipifarnib to preoperative chemotherapy increased the pathologic complete response rate (pCR) at surgery, and determined whether biomarkers predictive of pCR could be identified. EXPERIMENTAL DESIGN: Forty-four patients with stage IIB-IIIC breast cancer received up to four cycles of neoadjuvant doxorubicin-cyclophosphamide (AC) every 2 weeks plus tipifarnib and filgrastim followed by surgery. Enzymatic assays measuring FTase activity and Western blotting for phospho (p)-signal transducer and activator of transcription 3 (STAT3), phospho-extracellular signal-regulated kinase, p-AKT, and p27 were done in 11 patients who agreed to optional tissue biopsies before therapy and 2 hours after the final dose of tipifarnib during the first cycle, and predictive biomarkers were evaluated by immunohistochemistry in 33 patients. The trial was powered to detect an improvement in breast pCR rate of 10% or less expected for AC alone to 25% for AC-tipifarnib (alpha = 0.05, beta = 0.10). RESULTS: Eleven patients had a breast pCR (25%; 95% confidence interval, 13-40%). FTase enzyme activity decreased in all patients (median, 91%; range, 24-100%) and p-STAT3 expression decreased in 7 of 9 (77%) patients. Low tumor Ki-67 expression (below the median of 60%) at baseline was significantly associated with resistance to therapy (P = 0.01). CONCLUSION: Tipifarnib inhibits FTase activity in human breast tumors in vivo, is associated with down-regulation of p-STAT3, and enhances the breast pCR rate, thus meriting further evaluation.

A phase 2 study of an oral mTORC1/mTORC2 kinase inhibitor (CC-223) for non-pancreatic neuroendocrine tumors with or without carcinoid symptoms.

Second-generation mammalian target of rapamycin (mTOR) inhibitors such as CC-223 may have theoretical advantages over first-generation drugs by inhibiting TOR kinase in mTOR complex 1 (mTORC1) and 2 (mTORC2), potentially improving clinical efficacy for well-differentiated neuroendocrine tumors (NET).Enrolled patients had metastatic, well-differentiated NET of non-pancreatic gastrointestinal or unknown origin, with/without carcinoid symptoms, had failed ≥1 systemic chemotherapy, and were taking a somatostatin analog (SSA). Oral once-daily CC-223 was administered in 28-day cycles starting at 45 mg (n = 24), with a subsequent cohort starting at 30 mg (n = 23). Objectives were to evaluate tolerability, preliminary efficacy, and pharmacokinetic and biomarker profiles of CC-223. Forty-seven patients completed the study, with mean treatment duration of 378 days and mean dose of 26 mg; 26% of patients remained on the starting dose. Most frequent grade ≥3 toxicities were diarrhea (38%), fatigue (21%), and stomatitis (11%). By investigator, 3 of 41 evaluable patients (7%) showed partial response (PR) and 34 (83%) had stable disease (SD) for a disease control rate (DCR) of 90% (95% confidence interval [CI] 76.9-97.3%). Duration of PR was 125-401 days; median SD duration was 297 days (min-max, 50-1519 days). Median progression-free survival was 19.5 months (95% CI 10.4-28.5 months). Carcinoid symptoms of flushing, diarrhea, or both improved in 50%, 41%, and 39% of affected patients, respectively. For the first time, this study describes that a second-generation mTOR pathway inhibitor can result in highly durable tumor regression and control of NET carcinoid symptoms. The manageable safety profile, high DCR, and durable response, coupled with reduction in carcinoid symptoms refractory to SSA, make CC-223 a promising agent for further development.

Targeted inhibition of farnesyltransferase in locally advanced breast cancer: a phase I and II trial of tipifarnib plus dose-dense doxorubicin and cyclophosphamide.

PURPOSE: To determine the recommended phase II dose (RPTD) of the farnesyltransferase (FTase) inhibitor tipifarnib when combined with doxorubicin and cyclophosphamide (AC) in patients with advanced breast cancer, the pathologic complete response (pCR) rate after preoperative treatment with four cycles of the combination in locally advanced breast cancer (LABC), and the effect of tipifarnib on primary tumor FTase enzyme activity in vivo. PATIENTS AND METHODS: Thirty-two patients with metastatic breast cancer (n = 11) or LABC (n = 21) received AC (doxorubicin 60 mg/m2 and cyclophosphamide 600 mg/m2) administered intravenously on day 1 plus tipifarnib (100, 200, or 300 mg bid for 6 to 14 days) without (n = 2) or with (n = 30) granulocyte colony-stimulating factor (G-CSF) for up to four cycles. Patients with LABC underwent surgery after up to four cycles of the combination. RESULTS: When combined with AC every 2 weeks plus G-CSF, the RPTD of tipifarnib was 200 mg bid administered on days 2 to 7. Seven (33%) of 21 patients (95% CI, 15% to 55%) with LABC treated with up to four cycles of the combination at the RPTD had a pCR in the breast at surgery. The five patients had serial biopsies that demonstrated at least 50% FTase enzyme inhibition in the primary tumor (median, 100%; range, 55% to 100%) after tipifarnib. CONCLUSION: Tipifarnib may be safely combined with dose-dense AC using a dose and schedule that significantly inhibits FTase enzyme activity in human breast cancer in vivo and may enhance the pCR rate after four cycles of preoperative dose-dense AC.