Envafolimab, the First Subcutaneously Administered PD-L1 Antibody for HBV Enters Phase IIb Study
Around 257 million people worldwide are affected by the Hepatitis B virus (HBV), of which 70 million are from China. In August, the Phase IIa trial evaluating Ascletis Pharma Inc.’s PD-L1 antibody ASC22 (Envafolimab) demonstrated that it could possibly alleviate the symptoms of chronic hepatitis B (CHB). The promise led to the multi-dose Phase IIb study initiation meeting, held and chaired by Professor Guiqiang Wang, MD, Principal Investigator of the Study.
Known as KN035, ASC22 is a PD-L1 single domain antibody Fc fusion. The drug is convenient for storage at room temperature and delivery by subcutaneous administration. It tackles CHB with a mechanism of action that involves blocking the PD-1/PD-L1 pathway to enhance specific T cell function. This effectively targets HBV because T cell exhaustion is one of the major causes of the disease. In January 2019, Ascletis Pharma Inc. and Suzhou Alphamab Co. announced a strategic collaboration and licensing agreement for the drug to treat Hepatitis B and other viral diseases.
“We are excited about the initiation of this Phase IIb trial in CHB patients,” said Dr. Jinzi J. Wu, Founder, Chairman, and CEO of Ascletis. “As a first-in-class immunotherapy to clinically cure CHB, ASC22 (Envafolimab) has potential to be a cornerstone therapy in various treatment regimens, including combinations with our in-house developed drug candidates and potentially with drug candidates from other industrial leaders.”
“Therapeutic activity has been demonstrated for Envafolimab (KN035) in multiple oncology indications along with a strong safety profile emerging from more than 1000 patient exposure. Although tremendous progress in HBV treatment has been made recently, we are still in an uphill battle to cure this disease,” said Dr. Ting Xu, Chairman of Alphamab. “Because of its superior safety, convenience, and compliance, we are confident that KN035, as a first SubQ PD-L1 antibody, will offer a viable option for CHB patients.”
Phase IIa Study
The Phase IIa trial performed a single dose-escalation study with three different levels of ASC22, including 0.3, 1.0, and 2.5 mg/kg. With more than 1,000 participants involved in the study for safety and efficacy tests, all adverse events were grade 1, and no higher grades were observed or reported. The success of ASC22 led Alphamab to submit a new drug application for MSI-H solid tumors. Meanwhile, Shanghai Henlius Pharmaceuticals Co. recently enrolled 44 HBV patients for a Phase II clinical trial to evaluate ASC22’s major competitor, PD-1 inhibitor HLX10.
“Due to its unique immune mechanism, [Envafolimab] may also be used in patients with other chronic viral infections. The safety and convenience of subcutaneous administration [of it] have been reflected to the greatest extent in the treatment of chronic diseases,” Dr. Xu added.
By Judy Ya-Hsuan Lin
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