Otsuka Pharmaceutical Discontinues Multiple Cancer Drug Programs

Otsuka Pharmaceutical, a prominent Japanese drugmaker, has announced the discontinuation of several cancer drug candidates, citing strategic reasons. The decision affects four clinical-stage assets, including programs in the United States and Japan, marking a significant shift in the company's oncology pipeline.

OPB-111077: End of the Line for STAT Inhibitor

The most advanced candidate to face termination is OPB-111077, an oral STAT inhibitor that has been in clinical development since 2012. Initially showing promise, the drug had progressed to a combination study with bendamustine and rituximab in lymphoma patients. However, Otsuka halted enrollment in this trial prematurely in 2024, well short of its initial target.

Despite lymphoma emerging as the most promising indication in earlier studies, OPB-111077 demonstrated only "modest clinical activity" overall. The challenges faced by Otsuka mirror those of other research groups targeting STAT, including difficulties in achieving selectivity for STAT3 over related proteins.

Japanese Programs Cut Short

Three additional candidates developed exclusively in Japan have also been axed:

1. TAS0313: A peptide vaccine for advanced solid tumors, developed by Otsuka subsidiary Taiho Pharmaceutical. Despite "promising" data in combination with Merck's Keytruda for bladder cancer, the program failed to secure its future.

2. OPC-415: An MMG49 CAR-T cell therapy for multiple myeloma, licensed from Osaka University in 2018. The phase 1/2 trial, initiated in 2021, will not continue.

3. OPF-501C: A topical zinc chloride treatment for cancerous skin ulcers, whose phase 2 trial began in 2023 but will not progress further.

These decisions reflect Otsuka's broader strategic realignment in oncology, potentially signaling a shift in focus or resource allocation within the company's research and development efforts.