Sirolimus and trastuzumab combination therapy for HER2-positive metastatic breast cancer after progression on prior trastuzumab therapy.

Constitutive activation of the PI3K/Akt/mTOR pathway has been suggested as a mechanism of resistance to trastuzumab therapy. This phase II trial was designed to evaluate the safety and clinical activity of daily oral sirolimus, a mammalian target of rapamycin (mTOR) inhibitor, in combination with trastuzumab in HER2-positive metastatic breast cancer following disease progression on prior trastuzumab therapy. Sirolimus 6 mg oral daily dose was administered with a standard dose and schedule of trastuzumab weekly or every 3 weeks. Pharmacodynamic studies included Western blot analysis of S6K1, phosphoS6K1, and mTOR in peripheral mononuclear cells, circulating tumor cells (CTC), and endothelial cells (CEC). Eleven patients were evaluable for safety; and nine were evaluable for response assessment. Subsequent enrollment was stopped due to slow accrual. Study treatment-related grade 3 toxicity included pneumonitis, myelosuppression (leukopenia/anemia), and dermatologic reactions (mucositis, nail changes and rash), with no grade 4 events. One patient received eight cycles (58 weeks) and achieved a partial response. Five patients treated for a total of 101 weeks (median 12 weeks, range 8-47 weeks) achieved stable disease as best response. Overall response rate was 1/9 (11 %) and clinical benefit rate was 4/9 (44 %). There was no statistically significant correlation between response and post-treatment change in levels of the mTOR pathway biomarkers, CTCs, HER2 CTCs, or CECs. Sirolimus 6 mg administered daily with trastuzumab appears to be well tolerated in patients with metastatic HER2-positive breast cancer following disease progression on prior trastuzumab therapy, with evidence of disease activity. mTOR inhibition may overcome resistance to trastuzumab in some HER2-positive tumors.

Phase I clinical trial of the mammalian target of rapamycin inhibitor everolimus in combination with oral topotecan for recurrent and advanced endometrial cancer.

OBJECTIVES: Preclinical data suggest that mammalian target of rapamycin inhibitors may potentiate the efficacy of topotecan. We evaluated the optimal schedule of oral topotecan in combination with everolimus in patients with endometrial cancer. METHODS: Women with a history of advanced or recurrent endometrial cancer were enrolled. Escalating dose of oral topotecan (1.5 mg/m, 1.9 mg/m, and 2.3 mg/m) daily on days 1 to 5 and everolimus (5 mg every other day, 5 mg daily, and 10 mg daily) were administered in a 21-day cycle. A "run-in" treatment of topotecan daily for 5 days followed by everolimus for 7 days (4-7 doses depending on dose level) was administered for the purpose of pharmacokinetic assessments. RESULTS: Ten patients were enrolled on the study, and 9 were evaluable for safety analysis. A total of 28 cycles were administered (range, 1-10 cycles per patient). The patients had a median age of 73 years (range, 42-79 years). Previous lines of chemotherapy were 1 (n = 2), 2 (n = 5), 3 (n = 2), and 4 (n = 1). Seven patients had previous vaginal brachytherapy, and 2 had pelvic external beam radiation therapy. The median number of cycles (including cycle 1) is 2 (range, 1-10). Dose-limiting toxicity occurred in 3 patients (1 patient treated with 1.9-mg/m topotecan and 5-mg everolimus given every other day as well as 2 patients treated with 1.9-mg/m topotecan and 5-mg of everolimus daily) and included neutropenia and thrombocytopenia. Seven patients were evaluable for response. Stable disease was the best response in 3 patients who completed the 3, 4, and 10 cycles each. CONCLUSIONS: The dose-limiting toxicity for the combination of oral topotecan and everolimus was myelosuppression. The maximum tolerated dose was topotecan 1.9 mg/m on days 1 to 5 in combination with oral everolimus 5 mg every other day. Administration of higher dose of each agent in combination was limited because of overlapping myelosuppression.

ADAMTS13 activity and inhibitor.

Thrombotic thrombocytopenic purpura (TTP) is often associated with acquired or congenital deficiency of the von Willebrand factor-cleaving metalloprotease, ADMATS13 (Lammle B et al., J Thromb Haemost 2005;3:1663-1675; Schneppenheim et al., Blood 2003;101:1845-1850). Although undetectable levels of enzyme activity (<10%) are diagnostic of inherited or acquired TTP in the correct clinical setting (absence is specific), not all patients diagnosed with TTP have severe protease deficiency, and it is therefore not recommended as an initial test for diagnosis (Copelovitch and Kaplan, Pediatr Nephrol, in press). Many prospective and retrospective studies have demonstrated that patients with severe protease deficiency have a higher likelihood of relapse, making it helpful as an indicator of recurrence. The short-term prognostic usefulness of ADAMTS13 testing during acute TTP warrants further investigation because of limited prospective studies (Ferrari S et al., Blood 2007;109:2815-2822; Peyvandi et al., Haematologica 2008;93:232-239).