Samsung Bioepis said it has confirmed the safety and long-term efficacy profiles of Ontruzant (ingredient: trastuzumab), a biosimilar of cancer medicine trastuzumab, in a five-year follow-up study.

The company will present the results of its long-term study comparing Ontruzant ) and reference medicine trastuzumab in early or locally advanced human epidermal growth factor receptor 2 (HER2)-positive breast cancer at the virtual congress hosted by the European Society for Medical Oncology (ESMO).

“The five-year follow-up results are the longest monitoring data of patients treated with an Ontruzant for HER2-positive early or locally advanced breast cancer,” said Shin Dong-hoon, vice president and leader of the medical and lifecycle safety team at Samsung Bioepis. “The study results reflect our continuous dedication in producing high-quality treatments with proven efficacy and safety, and our commitment to patients with research and development to ensure quality treatment.”

Shin added that the company is looking forward to sharing the data analyzed in the five-year follow-up of biosimilars with the oncology community.

In the study, enrolled patients received eight cycles of the Ontruzant or trastuzumab with neoadjuvant therapy. Following the surgery, patients received 10 cycles of the Ontruzant or reference medicine, completing a year of treatment.

The company recruited 367 patients in the follow-up study -- 186 in the Ontruzant group and 181 in the reference medicine group -- with a median follow-up duration of 68 months.

Ontruzant and trastuzumab did not cause symptomatic congestive heart failure or cardiac death reported in either group. However, the company explained that the number of recurrences, progression, or death was reported in 32 patients, or 17.2 percent of the participants, in the Ontruzant group and 38 patients in the reference medicine group.

The five-year event-free survival rate of the patients reached 82.8 percent in the Ontruzant group and 79.7 percent in the trastuzumab group. Patients treated with Ontruzant recorded 93.1 percent of five-year overall survival rates. Those who received the reference medicine marked 86.7 percent, showing a similar therapeutic effect to the original drug.

The results of the five-year follow-up of the phase 3 study of Ontruzant will be presented as a poster at ESMO 2021 on Thursday.