Pfizer announced plans to acquire Array BioPharma, maker of a BRAF–MEK inhibitor combination that is currently approved for melanoma and could become a first-in-class treatment for colorectal cancer. The $11.4 billion deal also lands Pfizer a small pipeline of other targeted cancer medicines in development and a portfolio of out-licensed medicines with the potential to generate substantial royalties.

Last month, Array BioPharma announced that a pair of their drugs could dramatically improve outcomes for some patients with advanced colorectal cancer. Now, Pfizer has announced plans to acquire the Boulder, CO–based drugmaker in a deal valued at approximately $11.4 billion—and to maintain the company as a stand-alone research unit.

The agreement, unveiled on June 17, will give Pfizer two drugs, encorafenib (Braftovi) and binimetinib (Mektovi), approved by the FDA last year for patients with BRAF-mutant metastatic melanoma. Compared with other BRAF–MEK inhibitor combinations, the Array regimen is “better [than] or tied for best-in-class” in terms of efficacy and safety, according to Keith Flaherty, MD, of the Massachusetts General Hospital Cancer Center in Boston, MA, who led the drugs' clinical testing.

However, as this is the third BRAF–MEK inhibitor combination to reach the market for melanoma, that indication is unlikely to generate substantial revenues for Pfizer. What could push up sales of encorafenib–binimetinib is a supplemental approval for the treatment of BRAF-mutant metastatic colorectal cancer.

Currently, no drug regimens are specifically indicated for this type of disease. Patients often receive irinotecan-containing chemotherapy regimens plus the EGFR inhibitor cetuximab (Erbitux; Eli Lilly)—but encorafenib and binimetinib plus cetuximab looks to be a significantly better option.

In May, Array reported interim results from the phase III BEACON trial, which enrolled patients with colorectal cancer whose disease progressed despite treatment. (No other companies have advanced BRAF–MEK inhibitor combinations past phase II for this indication.) The data showed that Array's chemotherapy-free triplet regimen produced higher overall response rates (26% versus 2%) and longer overall survival times (9 months versus 5.4 months) compared with cetuximab and chemotherapy.

Array has said it intends to submit the data to U.S. regulators later this year, around the same time as the deal with Pfizer is expected to close. Meanwhile, Array is also evaluating its BRAF–MEK combo in patients with BRAF-mutant non–small cell lung cancer and as a first-line treatment with cetuximab for BRAF-mutant colorectal cancer.

In a statement, Pfizer CEO Albert Bourla, DVM, PhD, said the acquisition of Array's BRAF and MEK inhibitors “sets the stage to create a potentially industry-leading franchise for colorectal cancer.” However, the financial benefits could take years to accrue, with encorafenib and binimetinib not projected to cross the $1 billion annual threshold until the middle of the next decade, with about half the revenue stemming from a colorectal cancer–label expansion.

Ironically, the regimen could soon face competition from a Pfizer spin-off company called SpringWorks Therapeutics. On June 18, BeiGene and SpringWorks announced the creation of a joint venture called MapKure that will advance BeiGene's BRAF inhibitor, BGB-3245, likely in combination with a former Pfizer asset, the MEK inhibitor PD-0325901.

Pfizer gains more in the deal than encorafenib and binimetinib, however. For example, the sale includes ARRY-382, an inhibitor of colony-stimulating factor-1 receptor in a phase II combination trial with pembrolizumab (Keytruda; Merck) for patients with advanced solid tumors, as well as a portfolio of royalty-generating medicines that originated with Array before the company licensed them to others.

The royalty-generating assets include two marketed drugs, the TRK inhibitor larotrectinib (Vitrakvi; Bayer) approved in the United States last year, and danoprevir (Ganovo; Roche), a hepatitis C drug available in China, plus a handful of late-stage clinical candidates—the AKT inhibitor ipatasertib (Genentech), the MEK inhibitor selumetinib (AstraZeneca), the HER2 inhibitor tucatinib (Seattle Genetics), and the RET inhibitor LOXO-292 (Loxo/Eli Lilly). –Elie Dolgin

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