Antibody-drug conjugate (ADC) developer AbTis announced on August 14 that it has prevailed in an inter partes review (IPR) before the U.S. Patent Trial and Appeal Board (PTAB), successfully defending its core patent against a legal challenge by Japan’s Ajinomoto.
Ajinomoto had sought to invalidate a U.S. patent covering AbClick, AbTis’s proprietary ADC platform technology. AbClick is an ADC manufacturing technology that selectively attaches a drug to a specific site on an antibody—specifically, lysine 248. By standardizing both the conjugation site and the drug-to-antibody ratio, the technology helps ensure consistent product quality.
Ajinomoto, which holds its own site-specific antibody conjugation technology called AJICAP, has been engaged in a continuous patent dispute with AbTis in the ADC conjugation field.
In its final written decision, the PTAB rejected all invalidity arguments raised by Ajinomoto and upheld the patentability of AbTis’s core AbClick patent.
During the proceeding, Ajinomoto contended that the patent was invalid based on written description, enablement, and definiteness requirements under Section 112 of U.S. patent law, as well as novelty under Section 102 and nonobviousness under Section 103. The PTAB rejected each of those claims and dismissed all associated procedural and evidentiary arguments.
The ruling preserves the full validity of AbTis’s foundational patent protecting the AbClick platform in the United States.
Choi Hyung-seok, CEO of AbTis, said, "This decision confirms the validity of the core patent protecting the AbClick platform in the United States. Based on AbClick’s differentiated technology and patent competitiveness, we will expand global partnerships and technology commercialization while continuing to develop new ADC therapeutics."
AbTis was acquired by Dong-A ST to strengthen its ADC pipeline and platform capabilities. The company is currently pursuing both in-house ADC drug candidates and the commercialization of its AbClick platform technology.
