Pfizer scores FDA nod for Braftovi duo in colon cancer as investors await more lucrative triplet

When Pfizer shelled out $11.4 billion for Array BioPharma last year, it pointed to early data showing that Array’s BRAF inhibitor Braftovi, its anti-MEK drug Mektovi and the EGFR blocker Erbitux could extend lives in some patients with BRAF-mutant metastatic colorectal cancer (mCRC).

The data was so positive, in fact, it overshadowed the potential of another Array combo in the same patient population—Braftovi plus Erbitux.

Now, Pfizer has nabbed FDA approval for the Braftovi-Erbitux duo in some patients with metastatic BRAF-mutated colon cancer who have already been treated with chemotherapy. It is the first targeted regimen approved in this setting and is “a much-needed new treatment option for these patients,” said Scott Kopetz, M.D., Ph.D., associate professor of gastrointestinal medical oncology at the University of Texas MD Anderson Cancer Center, in a statement.

The approval was based on results from a trial called Beacon, in which the combination of Braftovi and Erbitux boosted overall survival to 8.4 months from 5.4 months for patients on chemo alone. The response rate for patients who received the duo was 20%, versus 2% for those treated with chemo.

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Still, the potential addition of Mektovi to the newly approved dual therapy—which was also investigated in the Beacon trial—is what investors have been most excited about in recent months. A few weeks before Pfizer announced the acquisition, Array released interim data showing that the response rate for the triplet therapy in BRAF-mutated mCRC was 26%.

Then in July, Array uncovered more detailed data showing that for the first 331 patients treated, the three drugs reduced the risk of death in mCRC patients by 26%, and that it extended lives by 9.5 months versus 8.3 months for the Braftovi-Erbitux combo. Some analysts concluded that the more mature data favored the triplet regimen.

Analysts at Cantor Fitzgerald aren’t so sure about that, though. They sent a note to investors after the FDA approved Braftovi-Erbitux predicting the duo—not the triplet—would become the standard of care in BRAF-mutated mCRC.

The Cantor Fitzgerald analysts spoke recently to a GI oncologist, who called the Braftovi-Erbitux combo “a likely favorite” for treating colon cancer patients who had already received chemotherapy, they said in a note to investors earlier this week.

Even though the triplet therapy has produced stronger data from clinical trials, the physician believes it “may still be reserved for patients who fail Braftovi [plus Erbitux],” Cantor Fitzgerald reported. The reason? The doublet will likely cost less than the triplet and carry fewer side effects.

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Pfizer is expected to shed more light on the prospects for the triplet therapy in the second half of this year, when it releases data from the phase 2 Anchor study in BRAF-mutated mCRC.

Meanwhile, the company has been preparing for a large-scale launch of the Array drugs in colorectal cancer. At the European Society for Medical Oncology annual meeting last fall, Pfizer executives reported that they were “very excited” about the unfolding data and were pouring the necessary resources into a successful launch in colorectal cancer.

The new approval marks the second FDA nod for Braftovi. The drug was first approved in June 2018, in combination with Mektovi, to treat metastatic melanoma with BRAF mutations. Cantor Fitzgerald estimates that the Braftovi-Mektovi franchise will be bringing in $955 million in sales by 2026.