CHICAGO—The investigational biosimilar MYL-1401O has comparable efficacy and safety to the branded, US Food and Drug Administration (FDA)-approved trastuzumab (Herceptin), according to results of a trial presented at the 2016 American Society of Clinical Oncology (ASCO) Annual Meeting, held June 3–7 in Chicago (abstract LBA503).
Overall response rates (ORRs) were “almost identical” for patients administered trastuzumab and those administered MYL-1401O, reported lead study author Hope Rugo, MD, Professor of Medicine at the University of California, San Francisco.
“Efficacy equivalence between MYL-1401O or Herceptin in combination with taxanes as first-line therapy for HER2-positive metastatic breast cancer at 24 weeks is statistically confirmed with similar safety, immunogenicity, and pharmacokinetics,” Dr. Rugo said.
The randomized, double-blind, phase III HERITAGE study enrolled patients at 95 centers in Asia, Latin America, Africa, and Europe. A total of 500 patients with metastatic HER2-positive breast cancer were enrolled; all were randomly assigned to receive taxane chemotherapy with either trastuzumab or MYL-1401O for at least 8 cycles, followed by trastuzumab alone until disease progression. Of these study participants, 458 were evaluable at 24 weeks for objective response rates (ORR) using RECIST 1.1 criteria.
The ORRs were 69.6% for patients in the MYL-1401O study arm, vs 64% for patients in the trastuzumab group. The ratio of ORRs was 1.09 (95% CI, 0.954–1.237), falling within the study’s pre-defined equivalence margin.
Safety findings were comparable for both groups, as well. Serious adverse events were primarily hematologic (most commonly and most seriously, neutropenia), and were reported in 38% of patients receiving MYL-1401O vs 36% of patients receiving trastuzumab, with four fatal events in each study arm. Cardiac function from baseline did not change significantly for either group by week 24, Dr. Rugo noted.
MYL-1401O demonstrated low immunogenicity—it did not trigger immune responses. Median progression-free survival (PFS) has not yet been reached, with 41 events in the MYL-1401O arm vs 48 events in the trastuzumab arm.
Targeted biologics like trastuzumab are complex and expensive therapeutics but patent periods for many of these drugs are expiring soon, and non–patent-protected biosimilar agents like MYL-1401O may offer a more affordable treatment option for patients around the world. “We hope that the introduction of biosimilars will expand patient access to this effective drug, which has already benefitted the lives of thousands of people across the globe,” Rugo said.