ADC Therapeutics S.A. (Épalinges, Switzerland) said it discontinued ADCT-502 after Phase I data of the antibody-drug conjugate (ADC) in patients with HER2-expressing advanced solid tumors did not show "sufficient patient benefit to justify further development."
ADCT-502 comprises an engineered version of trastuzumab, which is a humanized mAb against HER2, and a pyrrolobenzodiazepine (PBD) dimer toxin. The Genentech Inc. unit of Roche (SIX:ROG; OTCQX:RHHBY) markets Herceptin trastuzumab to treat HER2-positive cancers.
ADCT-502 did not achieve "the necessary efficacy at tolerated doses required for patient benefit," possibly due to "extensive expression of HER2 in pulmonary tissue," during dose escalation in the 21-patient trial, the company said. It plans to submit the data for publication this year.
ADC Therapeutics raised $200 million last fall, bringing its total funds raised to $455 million since its 2012 founding (see BioCentury, Oct. 26, 2017).
The company has three other ADCs in Phase I testing, including ADCT-301 and ADCT-402 for hematological malignancies and MEDI3726 for prostate cancer. It plans to start clinical testing of three additional programs over the next nine months.
ADCT-301 includes the CD25-targeted human mAb HuMax-TAC, while ADCT-402 targets CD19. Each is conjugated with a PBD dimer toxin.
MEDI3726 comprises a prostate-specific membrane antigen (PSMA; FOLH1; GCPII)-specific IgG1 mAb and a PBD dimer toxin. That program is partnered with the MedImmune LLC unit of AstraZeneca plc (LSE:AZN; NYSE:AZN).