Arvinas and Pfizer have entered an international partnership to jointly develop and market the former’s investigational therapy, ARV-471, for breast cancer.

ARV-471 is an oral proteolysis targeting chimera (PROTAC) estrogen receptor protein degrader.

It is presently being studied in a Phase II dose expansion clinical trial to treat patients with estrogen receptor (ER) positive/human epidermal growth factor receptor 2 (HER2) negative (ER+/HER2-) locally advanced or metastatic breast cancer.

As per the deal, Arvinas will receive an upfront payment of $650m from Pfizer.

In addition, Pfizer will make an equity investment of $350m, taking nearly 7% ownership in Arvinas.

Arvinas is additionally eligible for up to $400m on meeting regulatory approval milestones and up to $1bn in commercial milestones.

The global development and marketing costs and the profits on the product will be equally shared by the partners.

Pfizer and Arvinas will co-develop ARV-471 leveraging a strong clinical programme. This could make ARV-471 an endocrine backbone treatment of choice for breast cancer, including the adjuvant setting and late-line metastatic disease, Pfizer noted.

This year, the companies intend to launch two trials of the therapy with plans to commence Phase III trials next year.

Pfizer Oncology Research and Development chief scientific officer Jeff Settleman said: “Building on Pfizer’s established leadership position in breast cancer science and CDK 4/6 inhibition, we are excited to work with Arvinas to maximise ARV-471, the first PROTAC for breast cancer with encouraging early clinical data and a potential novel hormonal therapy backbone for HR+ breast cancer.

“This partnership complements Pfizer’s robust research activities in breast cancer, including our multiple next-generation CDK inhibitors currently in early clinical development.”

As per interim data from Phase I dose-escalation trial ongoing in locally advanced or metastatic ER+/HER2- breast cancer patients, ARV-471 demonstrated potential as a new oral ER targeted treatment.

The equity investment deal is anticipated to conclude on completing the review under antitrust laws and other necessary closing conditions.

This development comes after Pfizer and BioNTech signed a letter of intent with Biovac to produce their Covid-19 vaccine for supply in the African Union.