Puma Biotechnology Inc. reported positive results for one of the patient subgroups in an ongoing phase 2 trial of its lead breast cancer drug candidate PB272 or Nerlynx — a kinase inhibitor known chemically as neratinib.
The trial enrolled patients with HER2-positive metastatic breast cancer that had metastasized to the brain. There were three cohorts of patients and positive results were seen for patients in cohort 3A.
Cohort 3A had a total of 37 patients who had not received prior treatment with lapatinib. The patients had progressive brain metastases and were administered neratinib in combination with the chemotherapy drug capecitabine.
The primary endpoint of the trial was central nervous system, or CNS, objective response rate according to a composite criteria and the secondary endpoint was CNS response by response assessment in neuro-oncology-brain metastases, or RANO-BM criteria.
The results showed that 49% of patients experienced a CNS objective response by the composite criteria while the CNS response rate using the RANO-BM criteria was 24%. The median time to CNS progression was 5.5 months and the median overall survival was 13.5 months, though 49% of patients remain alive and survival data are immature.
The results also showed that the most severe adverse effect was diarrhea. Of the 37 patients, 32% had grade 3 diarrhea while 41% had grade 2 diarrhea.
A panel of the U.S. Food and Drug Administration voted 12-4 in favor of approval of Nerlynx on May 24. The FDA is expected to make a decision by July 21.
The Los Angeles biotech's shares had soared earlier in May over an FDA review of its application to market Nerlynx.
Puma had acquired the drug candidate from Pfizer Inc. in 2011.