Phase I trial of bortezomib and dacarbazine in melanoma and soft tissue sarcoma.

PURPOSE: Preclinical studies in human melanoma cell lines and murine xenograft tumor models suggest that the proteasome inhibitor bortezomib enhances the activity of the cytotoxic agent dacarbazine. We performed a phase I trial of bortezomib and dacarbazine in melanoma, soft tissue sarcoma, and amine precursor uptake and decarboxylation tumors. The primary objective was to identify recommended phase II doses for the combination. EXPERIMENTAL DESIGN: Bortezomib and dacarbazine were both administered intravenously once weekly. All patients received prophylactic antiemetics. Dose escalation proceeded using a standard 3 + 3 design. Response was assessed according to NCI RECIST v1.0. RESULTS: Twenty eight patients were enrolled to six dose levels. Bortezomib 1.6 mg/m(2) and dacarbazine 580 mg/m(2) are the recommended phase II weekly doses. The combination was generally well tolerated. Among 15 patients with melanoma there was one durable complete response in a patient with an exon-11 cKIT mutation, and one partial response. Among 12 patients with soft tissue sarcoma there was one partial response. CONCLUSIONS: Bortezomib 1.6 mg/m(2) and dacarbazine 580 mg/m(2) administered intravenously once weekly is well tolerated and has at least minimal activity in melanoma and soft tissue sarcoma.

Phase I trial and correlative laboratory studies of bryostatin 1 (NSC 339555) and high-dose 1-B-D-arabinofuranosylcytosine in patients with refractory acute leukemia.

A Phase I trial has been conducted in patients with refractory/relapsed acute leukemia in which escalating doses of the protein kinase C (PKC) activator and down-regulator bryostatin 1 (NSC399555), administered as a 24-h continuous infusion on days 1 and 11, were given immediately before and after a split course of high-dose 1-beta-D-arabinofuranosylcytosine (HiDAC; 1.5 g/m(2) every 12 h x 4) administered on days 2 and 3, and 9 and 10. The bryostatin 1 maximally tolerated dose (MTD) was identified as 50 microg/m(2), with myalgias representing the major dose-limiting toxicity (DLT). Other DLTs included prolonged neutropenia and thrombocytopenia, and hepatotoxicity. Of the 23 patients who completed their course of therapy and were fully evaluable for response, the large majority of whom had unfavorable prognostic characteristics, 4 complete remissions (CRs) were obtained. An additional 3 patients were treated at a 3 g/m(2) ara-C (1-beta-D-arabinofuranosylcytosine) dose level to determine whether this HiDAC dose could be administered in conjunction with bryostatin 1. All 3 of these patients experienced DLT, and this dose was considered above the MTD. However, one of the latter patients, who was heavily pretreated, also achieved a CR that persisted 5+ months without maintenance. Finally, 1 patient post-HiDAC and autologous bone marrow transplantation achieved a 5+ month leukemia-free survival although she did not meet the criteria for a CR because of persistent transfusion requirements. Correlative laboratory studies performed on blasts from 9 patients revealed that in vivo administration of bryostatin 1 resulted in variable effects on total blast PKC activity, including decreases in 4 samples, increases in 2, and no change in 3. Previous in vivo bryostatin 1 exposure also exerted disparate effects on the extent of apoptosis observed in blasts exposed to ara-C ex vivo, although increases were noted in a subset of patient samples. Interestingly, in vivo administration of bryostatin 1 by itself induced lethality in some patient specimens. No clear relationship between the in vivo effects of bryostatin 1 on blast PKC activity and the extent of ara-C-related apoptosis that occurred ex vivo was apparent. Together, these findings demonstrate that bryostatin 1 can be safely administered as a continuous infusion before and after a split course of HiDAC in patients with refractory leukemia, and identify the bryostatin 1 MTD as 50 microg/m(2) when given by this schedule. Furthermore, the achievement of several CRs in the setting of a Phase I trial in which many patients had particularly high-risk features (e.g., short initial remission, previous HiDAC or autologous bone marrow transplantation, and multiple previous salvage regimens) suggests that this regimen has activity in acute leukemia and warrants additional investigation.