Newly Reported Phase 3 Data Support Biosimilarity of HLX02 and Reference Trastuzumab

China-based drug maker Henlius, which is currently awaiting the European Medicines Agency (EMA)’s decision on its marketing authorization application for a trastuzumab biosimilar, HLX02, has reported new on its phase 3 trial of the drug in patients with breast cancer.

During the European Society for Medical Oncology (ESMO) Asia Congress 2019, held last week in Singapore, a research team led by Binghe Xu, MD, PhD, department of medical oncology at the Cancer Hospital Chinese Academy of Medical Sciences, Beijing, China, reported that the biosimilar met its primary end point of best overall response rate (ORR) at week 24.¹

The study was a randomized, double-blind, parallel-controlled study of the biosimilar and the EU-licensed reference trastuzumab conducted at 89 centers in China, the Philippines, Poland, and Ukraine.

In total, 649 patients with HER2-positive breast cancer were randomized to receive either the biosimilar (n = 324) or the reference trastuzumab (n = 325) with docetaxel on day 1 of the first cycle of chemotherapy, followed by their assigned trastuzumab every 3 weeks up to 12 months. The prespecified equivalence margin for the primary end point was set at  ±13.5%. Secondary endpoints included clinical benefit rate (CBR) and disease control rate (DCR), as well as safety up to 12 months.

The ORR at week 24 was 71.0% in the biosimilar group and 71.4% in the reference trastuzumab group (P = .952). The risk difference in ORR was —0.4% (95% CI, –7.4 to 6.6), which fell within the prespecified equivalence margin.

In all populations (including Asian patients versus non-Asian patients), similar range values of CBR were observed, at 78.6% to 86.8% in the biosimilar arm and 79.3% to 82.4% in the reference arm. Similar ranges for DCR were also reported, at 80.6% to 95.4% in the biosimilar arm and 86.9% to 89.2% in the reference arm. In total, 98.8% of patients in each arm reported at least 1 adverse event (AE).

Xu and colleagues concluded that using the biosimilar and the reference resulted in equivalent ORR at week 24, and that secondary analyses supported a conclusion of biosimilarity.

In a statement regarding the findings, Xu said that “Trastuzumab is not widely accessible around the world due to its high cost. The entry of more affordable versions of trastuzumab such as HLX02 could open up treatment access.”

He added that the biosimilar “has been rigorously evaluated by regulatory authorities such as the [EMA], based on sound scientific principles,” said Xu, and the product, if eventually authorized in Europe and in China, where it is also being considered by regulators, “has a clear potential to drive down spending on HER2+ cancer treatment.”

Data for the biosimilar were first reported² during the ESMO Congress 2019, held in Barcelona, Spain, in September.

References

1. Xu B, Zhang Q, Sun T, et al. First China-manufactured trastuzumab biosimilar HLX02 global phase III trial met primary endpoint in breast cancer. Presented at: European Society for Medical Oncology Asia Congress 2019; November 22-24, 2019; Singapore. Abstract LBA6.

2. Xu B, et al. Efficacy and safety of first China-manufactured trastuzumab biosimilar HLX02 for metastatic breast cancer: A phase III trial. Presented at: European Society for Medical Oncology Congress 2019; September 27 to October 1, 2019; Barcelona, Spain. Abstract 309PD.