J&J study halt reveals a crisis in follow-on antibody approaches

The quiet suspension of enrolment into a phase I trial of Johnson & Johnson/Genmab’s anti-CD123 bispecific, JNJ-63709178, marks the second time this asset has been put on clinical hold. J&J would not tell EP Vantage the reasons for the suspension, beyond confirming the grade 3 adverse event listed in the Clinicaltrials.gov database. The previous hold, also due to an undisclosed serious adverse event, lasted seven months before being lifted in April 2017. JNJ-63709178’s troubles look like the tip of the iceberg for follow-on antibody approaches such as bispecifics and antibody-drug conjugates (ADCs), many of which have recently hit the buffers. A phase I trial of Seattle Genetics’ CD123-targeting ADC, SGN-CD123A, was terminated in May, while last year J&J handed the CD19-targeting bispecific duvortuxizumab back to its originator, Macrogenics. Though one of the leading players, ADC Therapeutics, recently started a pivotal phase II study of its anti-CD19 ADC, ADCT-402, in total 10 ADC projects have suffered setbacks so far this year.