Medical Innovation Exchange

Astellas pays $175M for Propella, clearing early-phase rival to J&J’s Zytiga for takeoff

Astellas is spinning up a new attack on a cancer market, paying $175 million to buy Propella Therapeutics and its clinical-phase challenger to Johnson & Johnson’s fast-fading prostate cancer blockbuster Zytiga.

Propella’s lead candidate is PRL-02, an injectable formulation that is designed to improve on the benefits of Zytiga while eliminating some of that drug’s downsides. Like Zytiga, the treatment is designed to block an enzyme that is key to the production of androgens. By acting on the enzymes, the molecules could block the activation of androgen receptors that is implicated in the growth of metastatic prostate cancer.

North Carolina-based Propella believes its injectable, long-acting prodrug formulation has a compliance advantage over Zytiga, which is taken orally once a day on an empty stomach. And the biotech has begun to gather data to support its hypothesis that its candidate has safety and efficacy benefits. 

At the recommended dose, Zytiga maximally inhibits CYP17 hydroxylase and CYP17 lyase. Propella has designed its candidate to provide the level of abiraterone needed to block CYP17 lyase for 12 weeks. The goal is to block tumor growth without causing the safety concerns associated with inhibition of CYP17 hydroxylase.

Propella is putting that idea to the test in a phase 1/2a clinical trial. An early data drop from the ongoing study linked PRL-02 to a dose-proportional increase in abiraterone concentrations, as well as reductions in testosterone and prostate cancer biomarker PSA. No patients had treatment-related serious adverse events or dose-limiting toxicities, and steroid levels supported Propella’s CYP17 lyase selectivity claims. 

Astellas plans to move PRL-02 into phase 2a next year. The study will begin to reveal whether the ways in which PRL-02 is differentiated from Zytiga translate into better clinical outcomes. The past commercial performance of Zytiga suggests a safer, more effective alternative could rack up blockbuster sales. 

Generics have destroyed J&J’s Zytiga business in the U.S., which went from making $1.8 billion in 2018 to generating (PDF) $74 million last year, but international sales have held up better. Sales outside the U.S. fell 22.1% last year, including the impact of unfavorable foreign exchange, but still came in just a whisper away from $1.7 billion.

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