Phase III HLX02 Study Meets Primary End Point in Patients with HER2+ Breast Cancer

A multi-center phase III study reported that the trastuzumab (Herceptin) biosimilar, HLX02, met its primary end point of best overall response rate (ORR) at week 24, according to the China-based drug maker Henlius.1

The results, which were presented at the European Society for Medical Oncology (ESMO) Asia Congress 2019, suggested that HLX02 achieved similar ORR to that of China-sourced trastuzumab and European Union-sourced trastuzumab (EU-trastuzumab) in women with human epidermal growth factor receptor2 (HER2)-positive recurrent or previously untreated metastatic breast cancer.2

In the randomized cohort of 649 women, patients received 8 mg of either HLX02 or trastuzumab with docetaxel on day 1. This was followed by a dose of 6 mg in 3 weekly cycles for up to 12 months.

This interim analysis was submitted to NMPA and EMA to support marketing approval of HLX02 in China and Europe.

“The development of biosimilars is important both for patients, by improving access to cancer drugs, and for health systems, allowing cost savings that can be re-invested in patient care and support the sustainability of healthcare systems,” Rosa Giuliani, consultant medical oncologist, Clatterbridge Cancer Centre, said in a press release from ESMO.

Results showed a similar ORR at 24 weeks with HLX02 as with trastuzumab (71.0% vs 71.4%, P = 0.952). The risk difference in ORR between the 2 groups was -0.4% (95% CI; -7.4 to 6.6), which was within the predefined margin (+13.5%).

The secondary end points, including ORR at weeks 6, 12, and 18, clinical benefit rate, disease control rate, duration of response, progression-free survival (PFS), and overall survival (OS) at week 24 were similar for HLX02 and trastuzumab. The disease control rate was 83% in the HLX02 group and 84.3% in the trastuzumab group (P = 0.646). The median PFS with HLX02 was 11.7 months and 9.69 months with trastuzumab (P = 0.079).

There were no differences in safety profiles or immunogenicity between the 2 drugs. In each group, 98.8% of patients reported at least 1 adverse event (AE), and a similar number of AEs were reported in the 2 treatment groups.

“The development of biosimilars means that more women will have access to potentially life-saving HER2-targeted therapies because of the cost-savings they provide. Development of biosimilars introduces competition and potentially lowers the price of drugs,” Rebecca Dent, head, medical oncology, National Cancer Center Singapore, said in a press release.

The anti-HER2 antibody trastuzumab given in combination with chemotherapy has significantly improved OS in patients with HER-2 positive breast cancer, according to the ESMO release. However, the cost may limit patient access to this treatment in regions with limited financial resources for healthcare.

Several clinical trials are currently testing trastuzumab in combination with other treatments in treating patients with metastatic breast cancer.

References:
1. The Confirmatory Phase 3 Study Results of First China-Manufactured Trastuzumab Biosimilar, HLX02, will be Presented at Both CSCO and ESMO This Year [news release]. China. Published September 7, 2019. henlius.com/en/NewsDetails-1936-26.html. Accessed November 25, 2019.
2. First China-manufactured Trastuzumab Biosimilar HLX02 Global Phase III Trial Met Primary Endpoint in Breast Cancer [news release]. Singapore. Published November 22, 2019. esmo.org/Press-Office/Press-Releases/ESMO-Asia-Congress-2019-Biosimilars-Breast-Cancer-Trastuzumab-HLX02. Accessed November 25, 2019.