In an abstract presented at the recent American Society of Clinical Oncology meeting, researchers conducted a trial to evaluate the effectiveness and safety of trastuzumab biosimilar in the adjuvant setting among HER2+ BC patients.

In this national, multicentric, observational, and prospective real-world study, patients with early-stage HER2+ BC who were administered at least one dose of trastuzumab biosimilar as adjuvant therapy were eligible.

The study involved 162 patients. The researchers presented the preliminary safety data of the first 59 patients recruited in the study. The safety endpoint was the incidence of adverse events (AEs), and the safety population comprised all patients who received at least one dose of trastuzumab biosimilar.

Until the end of adjuvant treatment, researchers evaluated the AEs gathered from the signature of the consent form.

Among the 59 patients assessed, baseline patient characteristics included an average age of 51.7 ± 12.9 years, with 79.7% of patients being diagnosed with node-negative disease. The majority of patients had hormone-receptor-positive tumors (67.8% estrogen-receptor-positive and 55.9% progesterone-receptor-positive).

The number of patients undergoing conservative surgery and mastectomy was 67.8% and 32.2%, respectively. The most frequent histological BC subtype was invasive ductal carcinoma (98.3%). All 59 participants received adjuvant anti-HER2 therapy that included trastuzumab biosimilar administration trastuzumab biosimilar and pertuzumab (22.0%), and only two patients received the originator or reference trastuzumab, which was swapped to trastuzumab biosimilar upon entry into the study.

The authors wrote, “The duration of adjuvant anti-HER2 therapy was 10.2 ± 2.2 months, ranging from 5.8 to 13.9 months. This time corresponds to, on average, 14 ± 3.2 cycles of 21 days. In total, 78.0% of the patients had at least one AE, four of them were serious AEs (6.8%), including three of severe intensity and one life-threatening.”

Examples of reported adverse drug reactions among participants included:

• 13.6% reported general disorders and injection site issues
• 27.1% reported musculoskeletal and connective tissue disorders
• 13.6% reported infections
• 22% reported gastrointestinal issues.

The authors concluded that the characteristics and severity of AEs detected in patients utilizing trastuzumab biosimilar were comparable with the known safety profile of the originator product, trastuzumab.

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