Dive Brief:
- ADC Therapeutics SA has decided to discontinue development of its antibody drug conjugate ADCT-502 in advanced solid tumors with HER2 expression following analysis of data from a Phase 1 study.
- ADCT-502 combines a monoclonal antibody targeting HER-2 with the pyrrolobenzodiazepine dimer (PBD)-based anticancer compound tesirine. Drugs using PBDs are known to have certain side effects which limit the doses at which the drugs can be given.
- After a review of the results, ADC determined the candidate "did not demonstrate sufficient patient benefit to justify further development." The company plans to begin clinical testing of three other candidates this year, and advance two current clinical programs into later-stage development by the end of 2018.
Dive Insight:
While the HER2 program has been terminated, ADC Therapeutics will continue with other related projects that also focus on antibody drug conjugates.
Over the next nine months, the company plans to move two solid tumor and one hematological ADCs into the clinic. The solid tumor ADCs will include site-specific conjugation, which the company believes has the potential to improve tolerability and efficacy. Data presented earlier this month at the Annual Meeting of the American Association for Cancer Research (AACR) showed that two of these, ADCT-601 and ADCT-701, were well tolerated in animal studies.
Industry wide, research into ADCs has disappointed somewhat in recent years. Japanese company Astellas Pharma Inc. has backed out of the space, winding down its Agensys research operation and selling off the facility.
Elsewhere, AbbVie Inc. recently reported lackluster results for its ADC rovalpituzumab tesirine (Rova-T) in the third-line treatment of small cell lung cancer, although it is still holding out for first- and second-line data in the second half of 2019. And just last month, Pfizer Inc. dropped a collaboration with CytomX Therapeutics Inc. after not moving any candidates into the clinic in four years.
That's not to say there hasn't been any successes, though. Seattle Genetics Inc. leads the way with its ADC Adcetris (brentuximab vedotion), while Daiichi Sankyo Co. has invested $135 million in manufacturing expansion for the dual-threat medicines.