(Reuters) – U.S. Food and Drug Administration staff reviewers said an accelerated review of drugmaker Amgen Inc’s skin cancer immunotherapy cannot be considered at this time, citing concerns over the design and results of a key study.

The reviewers said in documents made public on Monday that it was unclear whether the treatment, a cancer-killing virus called talimogene laherparepvec or “T-Vec”, improved overall survival, raising questions over its effectiveness.

The review comes two days before a panel of FDA advisers votes on whether T-Vec should be approved to treat melanoma.

The FDA typically accepts the panel’s recommendations.

The panel will also discuss whether the study’s main goal of showing an improvement in the durable response rate was meaningful. (1.usa.gov/1djTiQs)

T-Vec represents a new class of agent for the treatment of metastatic melanoma and Amgen is looking forward to discussing the data at the joint FDA advisory committee meeting on Wednesday, the company told Reuters.

The engineered virus is injected into tumors to kill cancer cells and also primes the immune system to attack the disease.

The staff review comes about two months after the FDA pushed back a decision on approving the drug to Oct. 27 from July 28, citing the need for manufacturing data.

Melanoma, the most aggressive form of skin cancer, is the fifth most common cancer. The American Cancer Society estimates that about 73,870 new melanomas will be diagnosed in the United States this year.

T-Vec is also being considered for approval in the European Union.

Amgen is already testing T-Vec in combination with Bristol-Myers Squibb’s melanoma drug Yervoy and separately with Merck & Co’s experimental immunotherapy, Keytruda.

Amgen’s shares fell 1.5 percent to $165.35 in morning trading on the Nasdaq.



(Editing by Simon Jennings)