In a trio of studies, investigators were able to demonstrate equivalency of Samsung Bioepis’ trastuzumab biosimilar in various settings.
Incheon, Republic of Korea company Samsung Bioepis reported clinical trial data from 3 studies of its trastuzumab biosimilar (Ontruzant) that demonstrate equivalency to the reference product, Herceptin, in various settings. In April, the biosimilar was launched on the US market.
The results will be presented at the upcoming American Society of Clinical Oncology meeting (ASCO20 Virtual Scientific Program).
Ontruzant Combination Therapy pCR Rate
Using data from the Danish Breast Cancer Cooperative Group registry, investigators sought to assess the real-world efficacy of combining neoadjuvant chemotherapy (NACT) with Ontruzant and pertuzumab in patients with HER2-positive early breast cancer.
Overall, 56% of patients (n = 215) achieved a pathologic complete response (pCR) and 68% of patients who were node positive before receiving the combination of NACT, Ontruzant, and pertuzumab had tumor-free axillary nodes after completing the regimen.
Investigators said the pCR rate for the Ontruzant combination that was comparable to that seen in clinical studies involving Herceptin in combination with NACT and pertuzumab.
Cardiotoxicity of Ontruzant Plus Pertuzumab
Because cardiotoxicity is a concern during trastuzumab therapy, it is important to understand the safety profile of biosimilars in this regard. Investigators at the Medical University of Graz in Austria sought to measure potential decline in left ventricular ejection fraction (LVEF) for patients with HER2-positive breast cancer receiving Ontruzant and pertuzumab.
All patients (n = 35) had a normal baseline LVEF (> 50%) prior to starting Ontruzant and pertuzumab, and the median LVEF was 60%. At the end of treatment (median 4 cycles), the median LVEF was 60%.
The safety and efficacy profile of Ontruzant and pertuzumab was consistent with Herceptin and pertuzumab, researchers said.
Cardiac Safety and Survival by ADCC Status
In a study of long-term cardiac safety and survival, investigators evaluated Ontruzant versus Herceptin in patients stratified by antibody-dependent cell-mediated cytotoxicity (ADCC) status.
They enrolled 367 patients, with 186 receiving Ontruzant and 181 receiving Herceptin. During a median follow-up of 53 months, the incidence of asymptomatic LVEF decrease was low (1 patient on Ontruzant and 2 on Herceptin), with all patients recovering with LVEF ≥50%. There were no cases of symptomatic congestive heart failure, cardiac death, or other significant cardiac conditions reported.
The 4-year event-free survival rates were 83.4% for the biosimilar and 80.7% for the reference product (HR, 0.77). The 4-year overall survival rates were 94.3% versus 89.6% (HR, 0.53), respectively.
“Comparable long-term cardiac safety and survival at 4-years supports biosimilarity,” investigators wrote.
The ASCO20 Virtual Scientific Program will be presented May 29 to 31, 2020.