Simotaxel

Purpose: To compare clinical outcomes of metastatic head and neck cancer patients treated in phase I clinical trials with clinical outcomes of those patients who had their last Food and Drug Administration (FDA)–approved therapy in the setting of metastatic disease.Experimental Design: We retrospectively reviewed the outcomes of 61 consecutive patients with head and neck tumors treated in 36 phase I trials at The University of Texas M.D. Anderson Cancer Center between July 2004 and September 2009.Results: The most common histology was head and neck squamous cell carcinoma (62%). Median age was 55 years (range, 26-80). Eastern Cooperative Oncology Group performance status was 0 to 1 for 95% of patients. Fifty-nine patients had received FDA-approved drugs as the backbone of their last systemic therapy before inclusion in phase I trials (median, 2 systemic therapies). Progression-free survival (PFS) on phase I trials was not inferior to PFS on their last FDA-approved therapies (12 versus 10.7 weeks, log-rank P = 0.87). Fifty-three patients were evaluable for response by Response Evaluation Criteria in Solid Tumors criteria. Four (7%) had partial responses and 16 (26%) had stable disease for ≥4 months. In univariate analysis, number of metastatic sites, lactate dehydrogenase (LDH) levels at baseline, and Royal Marsden Hospital prognosis scores were significant predictors of survival. Only LDH was significant in multivariate analysis (hazard ratio, 6.35; P ≤ 0.0001).Conclusions: For patients with heavily pretreated advanced head and neck tumors, PFS on phase I trials is not inferior to PFS with their last FDA-approved therapy. The only significant predictor of survival in the multivariate analysis was baseline LDH. Clin Cancer Res; 16(15); 4031–7. ©2010 AACR.

Purpose: Because resistance to paclitaxel and docetaxel is frequently observed in the clinic, new anti-microtubule agents have been sought. The aim of this study was to evaluate the efficacy and oral activity of a novel taxane (MST-997) in paclitaxel- and docetaxel-resistant tumor models in vitro and in vivo.Experimental Design: Tubulin polymerization assays, immunohistochemistry, and cell cycle analysis was used to evaluate mechanism of action of MST-997. The effect of MST-997 on growth inhibition in a panel of paclitaxel- and docetaxel-resistant cell lines that overexpressed P-glycoprotein (MDR1) or harbored β-tubulin mutations were assayed in vitro and in murine xenografts.Results: MST-997 induced microtubule polymerization (EC50 = 0.9 μmol/L) and bundling, resulting in G2-M arrest and apoptosis. In addition, MST-997 was a potent inhibitor of paclitaxel- and docetaxel-sensitive tumor cell lines that did not have detectable P-glycoprotein (IC50 = 1.8 ± 1.5 nmol/L). Minimal resistance (1- to 8-fold) to MST-997 was found in cell lines that either overexpressed MDR1 or harbored point mutations in β-tubulin. Most notable, MST-997 displayed superior in vivo efficacy as a single i.v. or p.o. dose either partially or completely inhibited tumor growth in paclitaxel- and docetaxel-resistant xenografts.Conclusions: MST-997 represents a potent and orally active microtubule-stabilizing agent that has greater pharmacologic efficacy in vitro and in vivo than the currently approved taxanes. Our findings suggest that MST-997, which has entered phase I clinical trials, may have broad therapeutic value.