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ABSTRACT: Background
This phase 1/2 study evaluated the dose-limiting toxicity and maximum tolerated dose of MLN2704, a humanized monoclonal antibody MLN591 targeting prostate-specific membrane antigen, linked to the maytansinoid DM1 in patients with progressive metastatic castration-resistant prostate cancer.Patients and methods
A total of 62 patients received MLN2704 at ascending doses on 4 schedules: weekly (60, 84, 118, and 165mg/m2; 12 patients); every 2 weeks (120, 168, 236, and 330mg/m2; 15 patients); every 3 weeks (330 and 426mg/m2; 18 patients); and on days 1 and 15 of a 6-week schedule (6-week cycle, 330mg/m2; 17 patients). The primary efficacy endpoint was a sustained ≥50% decline from baseline prostate-specific antigen (PSA) without evidence of disease progression. Toxicity, pharmacokinetics, immunogenicity, and antitumor activity were assessed.Results
Neurotoxicity was dose-limiting. Overall, 44 patients (71%) exhibited peripheral neuropathy: 6 (10%) had grade 3/4. Neurotoxicity rates remained high despite increasing the dosing interval to 3 (13 of 14; one grade 3) and 6 weeks (16 of 17; three grade 3). MLN2704 pharmacokinetics were dose-linear. Rapid deconjugation of DM1 from the conjugated antibody was seen. In all, 5 patients (8%) experienced ≥50% decline in PSA; 5 (8%) had PSA stabilization lasting≥90 days. Only 2 of 35 patients on the 3- and 6-week schedules achieved a PSA decline of >50%.Conclusions
MLN2704 has limited activity in metastatic castration-resistant prostate cancer. Disulfide linker lability and rapid deconjugation lead to neurotoxicity and a narrow therapeutic window.
SUBMITTER: Milowsky MI
PROVIDER: S-EPMC5464417 | biostudies-literature | 2016 Dec
REPOSITORIES: biostudies-literature
Milowsky Matthew I MI Galsky Matthew D MD Morris Michael J MJ Crona Daniel J DJ George Daniel J DJ Dreicer Robert R Tse Kin K Petruck Jesika J Webb Iain J IJ Bander Neil H NH Nanus David M DM Scher Howard I HI
Urologic oncology 20161017 12
<h4>Background</h4>This phase 1/2 study evaluated the dose-limiting toxicity and maximum tolerated dose of MLN2704, a humanized monoclonal antibody MLN591 targeting prostate-specific membrane antigen, linked to the maytansinoid DM1 in patients with progressive metastatic castration-resistant prostate cancer.<h4>Patients and methods</h4>A total of 62 patients received MLN2704 at ascending doses on 4 schedules: weekly (60, 84, 118, and 165mg/m<sup>2</sup>; 12 patients); every 2 weeks (120, 168, 23 ...[more]