A new biosimilar to trastuzumab (Herceptin) antibody, MYL-14010, showed efficacy and safety comparable to the reference drug (trastuzumab) as first-line treatment for patients with HER2-positive advanced breast cancer, according to results from the 24-week, randomized phase 3 HERITAGE study presented at ASCO 2016.
The 24-week objective response rate (ORR) was 69.6% with biosimilar MYL-14010 versus 64% with the reference drug trastuzumab. The safety was comparable between the 2 groups.
“This is one of the first trials with biosimilars in oncology to demonstrate similar efficacy, safety, and immunogenicity against the reference product. We hope that this will expand access to this effective drug, which has already benefited the lives of thousands of people around the globe,” said lead investigator Hope S. Rugo, MD, Director, Breast Oncology Program, Helen Diller Family Comprehensive Cancer Center, University of California San Francisco.
“These results using a proposed biosimilar are incredibly exciting,” said Don S. Dizon, MD, FACP, Clinical Co-Director of Gynecologic Oncology, Massachusetts General Hospital, Boston, who moderated a press conference at the meeting where Dr Rugo presented these results. “This has the potential to broaden access to a lifesaving agent. I await the final results.”
The HERITAGE Study
The randomized, double-blind, phase 3 HERITAGE trial was conducted at 95 sites across Asia, Latin America, and Europe. The study enrolled 458 women with metastatic, HER2-positive breast cancer and randomized them to first-line treatment with investigator’s choice of a taxane (docetaxel or paclitaxel) plus MYL-14010 versus taxane plus trastuzumab. The patients received treatment for a minimum of 8 cycles; treatment was continued until disease progression.
At week 24, the ORR was 69.6% for the biosimilar versus 64% for branded trastuzumab. The difference in ORR between the 2 treatment arms was 5.5%, which fell within the equivalency range.
The new biosimilar and the reference drug trastuzumab had comparable safety. The rate of serious adverse events was 38.1% in the biosimilar arm versus 36.2% in the reference trastuzumab arm. Neutropenia was the most common serious adverse event in both arms (27.5% vs 25.2%, respectively), and no difference in cardiac function was observed between the 2 arms.
Both treatment arms had a similar rate of antidrug antibody formation—2.4% for the biosimilar and 2.8% for branded trastuzumab. This rate is consistent with published trastuzumab data, Dr Rugo said.
The 24-week data in the HERITAGE trial met the regulatory requirements for a biosimilar, and it is hoped that the biosimilar will soon be approved by the US Food and Drug Administration. It is not clear what the cost will be. The biosimilar filgrastim-sndz, which is available on the market, costs approximately 15% less than its reference drug filgrastim (Neupogen).
“As a researcher, we don’t know how the price of a biosimilar is determined,” Dr Rugo noted. “I have heard that the estimated cost should be about 30% lower than that of trastuzumab.”