Pfizer's (PFE.US) study on the new breast cancer drug Vepdegestrant was mixed, and Arvinas (ARVN.US) stock price plummeted 40%

The Zhitong Finance App learned that Pfizer (PFE.US), Vepdegestrant, a next-generation drug used to treat breast cancer, has achieved mixed results in the final stages of research, which may be a setback for the company's new drug that it once called a potentially blockbuster drug.

According to a statement released by the company on Tuesday, the drug called Vepdegestrant failed to significantly slow cancer progression in all patients participating in the study, but it met expectations for those subgroups of patients with specific genetic mutations. Pfizer said it will share the findings with health regulators to support approval of vepdegestrant.

Pfizer has added vepdegestrant to a list of eight potentially major anti-cancer drugs in its R&D pipeline. If this treatment is only approved for breast cancer patients with specific mutations, its future market size will be drastically reduced. Biotech company Arvinas Inc. (ARVN.US) has licensed vepdegestrant to Pfizer and has the right to share profits.

Arvinas shares fell more than 40% in pre-market trading in New York. Pfizer's stock price, on the other hand, has hardly changed.

Pfizer is looking for new products to help reverse its post-pandemic decline and is betting heavily on new cancer treatments. In 2023, Pfizer bought Oncology-focused Seagen Inc., for $43 billion, and CEO Albert Borah has repeatedly pointed out that the company's anti-cancer drug development pipeline is an underappreciated source of future growth.

Vepdegestrant is a daily pill designed to supplement Pfizer's blockbuster breast cancer treatment, Ibrance. This key study enrolled 624 patients who had not recovered from breast cancer after receiving Ibrance or similar therapy. Half of the patients were treated with Vepdegestrant, and the other half were injected with a standard hormone therapy called fulvestrant. Pfizer said it will present detailed results of the study at a future medical conference.