Dive Brief:

• Pfizer’s Talzenna medicine gave patients with a form of metastatic prostate cancer a significantly better chance at survival without disease progression in a study released Thursday.
• The trial included patients with certain genetic mutations and whose disease was still sensitive to testosterone-lowering treatments, a group that’s especially vulnerable to tumor progression. Participants received either Talzenna or a placebo in combination with an older cancer therapy known as Xtandi, which Pfizer co-markets with Astellas Pharma. 
• Researchers then used imaging to measure the effects on tumors, finding that Talzenna exceeded the pre-specified goal in helping patients avoid worsening cancer. An early analysis also detected a “trend” towards a survival benefit, Pfizer said.

Dive Insight:

Pfizer says it will share the results with global regulators, which may lead to an expanded approval. The combination of Talzenna and Xtandi is already cleared for patients with so-called HRR gene mutations and whose tumors stopped responding to hormone treatments, a classification known as “castration resistant.” A broader label would include patients earlier in their disease course.

An expansion would probably be “negligible” for Pfizer in terms of revenue, but it’s “a win for patients” who need better options, RBC Capital Markets analyst Trung Huynh wrote in a note to clients. Xtandi will lose patent protection soon and while sales of Talzenna climbed 55% last year, the drug still only brought in $182 million, a small contributor to the almost $17 billion in Pfizer’s oncology portfolio.

Talzenna is part of a class of drugs known as PARP inhibitors, once seen as surefire blockbuster therapies for cancer. Between 2016 and 2019, a flurry of deals focused on the medicines: Pfizer acquired Talzenna in a $14 billion takeover of Medivation; GSK gained Zejula through a $5.1 billion buyout of Tesaro; and AstraZeneca and Merck & Co. inked an $8.5 billion deal centered on Lynparza.

Lynparza is the market leader and the drug has attained blockbuster status, with more than $3 billion in revenue last year. But its sales pale in comparison with other cancer therapies such as Merck’s Keytruda, which brought in almost $32 billion, and Johnson & Johnson’s Darzalex, which had revenue of more than $14 billion. And others in the PARP class lag well behind Lynparza.

Safety concerns have hurt the drugs, as well as research that found the medicines help smaller subsets of patients than originally envisioned. After winning approval for a subset of breast cancer patients in 2018, Pfizer aimed for a broad expansion into metastatic prostate cancer, but the Food and Drug Administration gave it a narrow approval instead. Another bid by Pfizer to expand Talzenna’s use beyond patients with the HRR gene mutations fell flat last year.