Phase I Study of LFA102 in Patients With Advanced Breast Cancer or Castration-resistant Prostate Cancer.

BACKGROUND/AIM The prolactin receptor (PRLR) is implicated in the tumorigenesis of breast and prostate cancers where it drives cell proliferation, survival, and migration. LFA102 is a humanized monoclonal antibody against PRLR with promising preclinical antitumor activity. To determine the maximum tolerated dose or a recommended dose, and to delineate the pharmacokinetic profile of LFA102 in Japanese patients, we conducted a phase I study. PATIENTS AND METHODS LFA102 was intravenously infused every 4 weeks to patients with advanced breast or castration-resistant prostate cancer, and the dose increased from 3 to 40 mg/kg. RESULTS Fourteen patients were treated, and toxicities were reported in 9 (64%) patients. They were all grade 1 or 2, and the most frequently observed toxicity was nausea (3 patients, 21%). No dose-limiting toxicities were observed. LFA102 did not show antitumor activity as a single agent. CONCLUSION Treatment with LFA102 was well tolerated.