Bristol-Myers Squibb's immuno-oncology drug Opdivo (nivolumab) was declined approval by the U.S. Food and Drug Administration (FDA) for expanded usage in the treatment of metastatic melanoma, an advanced type of skin cancer.

The pharmaceutical company received the FDA's Complete Response Letter asking for additional data on the BRAF mutated patient population. The BRAF is a gene in humans responsible for the creation of a protein called B-Raf.

A Complete Response Letter is issued by the U.S. health regulator when a generic or new drug's current form cannot be approved. On Nov. 23, the FDA approved Opdivo as a single agent for the treatment of BRAF V600 wild-type melanoma. On Nov. 27, the agency declined approval for the drug to be used in the treatment of BRAF V600 mutation positive metastatic melanoma.

"Bristol-Myers Squibb is working to evaluate the request outlined by the FDA and will continue to work closely with the agency to determine whether additional data, currently under review, adequately addresses these comments," wrote the pharmaceutical company in a press release.

The company submitted a separate supplemental biologics license application (sBLA) for BRAF-mutant advanced melanoma. The sBLA was based on the CheckMate-067 trial's phase III results. The FDA granted the sBLA a priority review and set a Jan. 23, 2016 deadline.

The researchers analyzed 945 metastatic melanoma patients in the CheckMate-067 study where they received nivolumab, ipilimumab, or a combination of nivolumab and ipilimumab and then followed by nivolumab. One third of the patients in the study were BRAF mutation-positive.

Dr. Jedd Wolchok of the Memorial Sloan Kettering Cancer Center stressed that both single-agent (nivolumab alone) and combined (nivolumab with ipilimumab) treatments were able to substantially improve the rates of progression-free survival when compared to ipilimumab treatment alone among patients with untreated melanoma. Wolchok is the center's melanoma and immunotherapeutics service chief and the study's lead author. The findings were shown at the annual meeting of the American Society of Clinical Oncology.

Opdivo's first approval was in December 2014. In nine months, the drug generated a $467 million worldwide revenue. In the past year, the drug was approved for five other health indications.