Merck KGaA, Pfizer bag 'breakthrough' status for PD-L1 immunotherapy

Merck KGaA and Pfizer ($PFE) have bagged FDA breakthrough therapy designation for avelumab, the pair's anti-PD-L1 monoclonal antibody. And while the immunotherapy is lagging behind rivals' PD-1 and PD-L1 drugs in some indications, Merck KGaA and Pfizer think the breakthrough status could help them steal a lead in metastatic Merkel cell carcinoma (MCC).

MCC, a rare form of skin cancer, is currently treated with either surgery, chemotherapy or radiation therapy, none of which are effective in all situations. Recognizing this, the FDA has awarded avelumab breakthrough status as a treatment for people with metastatic MCC whose disease has progressed after a round of chemotherapy. The regulator gained the impression that avelumab may be able to help such patients after getting an early look at data from an 88-person Phase II clinical trial, the full readout from which is due for publication next year.

With Phase II data on the horizon and breakthrough status in the bag, Merck KGaA and Pfizer have tipped avelumab to become the first immunotherapy approved for the treatment of MCC. Merck ($MRK), Bristol-Myers Squibb ($BMY), Roche ($RHHBY) and AstraZeneca ($AZN) all have PD-1 or PD-L1 immunotherapies that are further through development than avelumab, but none of these rivals have prioritized MCC to the extent of Merck KGaA and Pfizer. A team at the Fred Hutchinson Cancer Research Center has looked at Merck's Keytruda in MCC, but few others have run trials.

The homing in on the indication has given Merck KGaA and Pfizer an opportunity to leapfrog rivals, at least in a small corner of the PD-L1 market. Merck KGaA and Pfizer have turned to FDA for help with bringing avelumab to market as fast as possible. "In less than two months, the alliance between Merck KGaA, Darmstadt, Germany, and Pfizer has achieved its third regulatory milestone for avelumab, including orphan drug designation and fast track designation granted in September and October," Pfizer SVP Mace Rothenberg said in a statement.

MCC has garnered the most headlines in recent months, but Merck KGaA thinks avelumab can also claim a spot among the first immunotherapies to win approval for the treatment of ovarian, gastric, bladder and renal cancers. Carving out a stake in these markets would go some way toward justifying the $850 million Pfizer handed over to buy into Merck KGaA's immunotherapy pipeline.

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