US regulators need more time to make a decision on Bristol-Myers Squibb’s experimental melanoma drug ipilimumab, but the company remains confident in its ultimate approval.

The US Food and Drug Administration will now make a decision on the drug by March 26 next year instead of its prior Christmas Day target, giving it enough time to assess a further analysis of data submitted by B-MS which the agency considers to be a major amendment to the application to market the drug for pre-treated advanced melanoma.

Ipilimumab - a fully human monoclonal antibody that essentially works by boosting the immune system’s T-cell response - was actually originally granted a priority review back in August, which is given to therapies that potentially offer significant advances in treatment or address an unmet medical need.

The drug’s filing is based on data from the pivotal MDX010-020 trial, published online in the <i>New England Journal of Medicine</i>, which looked at the overall survival rate of patients taking ipilimumab plus the vaccine glycoprotein (gp100), just ipilimumab, and gp100 (the control) alone.

The results showed that patients taking ipilimumab, both with or without the gp100 vaccine, survived for around 10 months versus six months for those given gp100 alone, clearly demonstrating its potential to extend life in patients with the disease.

Potential blockbuster?

Despite the review going into extra time, B-MS says it continues to be very encouraged by its interactions with the FDA and remains “confident in the overall development program for ipilimumab”.

The drug, which is also under review in Europe and elsewhere, can be associated with severe side effects, but given that treatment options for patients with advanced melanoma – one of the deadliest forms cancer – are thin on the ground, analysts are still expecting ipilimumab to achieve blockbuster status, with peak sales overshooting the $1 billion-mark.