South Korean biotechnology company AbTis, which develops antibody-drug conjugate (ADC) technologies, said the US Patent Trial and Appeal Board (PTAB) has upheld its US patent covering the company's exclusive AbClick platform, defeating a challenge brought by Anjinmoto.

Anjinmoto initiated the review, asserting that the patent failed to meet US requirements for written description, enablement and definiteness under Section 112 of the US Patent Act. The petitioner also raised challenges based on anticipation under Section 102 and obviousness under Section 103, along with procedural and evidentiary objections.

Inter partes review is a USPTO procedure through which third parties can ask the PTAB to cancel an issued US patent on grounds such as anticipation and obviousness. In a final written decision issued in inter partes review, the PTAB rejected all of the petitioner's challenges, leaving the patent in force.

The dispute lands in one of biopharma's most deal-heavy technology areas. ADCs link tumor-targeting antibodies to cytotoxic payloads, aiming to deliver cell-killing agents to cancer cells while limiting harm to healthy tissue, and approved products such as Roche's Kadcyla and AstraZeneca and Daiichi Sankyo's Enhertu have made the class a major oncology franchise. The field has also attracted a wave of multibillion-dollar partnerships and acquisitions, including Pfizer's roughly $43 billion takeover of ADC specialist Seagen in 2023.

AbClick is AbTis' site-specific ADC conjugation platform, which enables drug payloads to be attached to the Lys248 residue of an antibody's Fc region. The technology is designed to produce highly homogeneous ADCs with controlled drug-to-antibody ratios and consistent product quality. Traditional conjugation methods attach payloads at variable positions and tend to yield heterogeneous mixtures with differing drug-to-antibody ratios, a long-standing manufacturing and quality-control hurdle that site-specific platforms are engineered to avoid.

For platform biotechs that monetize through licensing, durable patents are a core part of the asset, and prospective partners typically scrutinize the strength of underlying IP during due diligence. AbTis is developing multiple ADC programs based on the platform and pursuing collaborations with global biopharmaceutical companies. Drawing on the PTAB's decision, the company plans to expand its presence in the US and pursue future technology licensing and new partnerships.

"The board's decision provides significant objective support for the originality and patent competitiveness of our platform," said Choi Hyung-seok, CEO of AbTis. "Backed by the victory, we will accelerate strategic partnerships and commercialization of our technology worldwide."

Source: Korea Herald Business