In the week when US regulators are expected to decide on approval for  Bristol-Myers Squibb's ipilimumab, the company has presented promising late-stage data on the skin cancer drug.

The New York-based major says ipilimumab has met the primary endpoint of improving overall survival in previously-untreated patients with metastatic melanoma in a Phase III trial. Participants in the study, called 024, were suffering from unresectable stage III or stage IV melanoma, the most advanced form of the disease and had not received prior therapy.

The study compares ipilimumab 10mg/kg in combination with the chemotherapy dacarbazine versus chemotherapy alone. B-MS gave no specific details about the study or the extent of the overall survival benefit but noted that an abstract of the 024 data will be submitted to the American Society of Clinical Oncology for potential presentation at the latter's June meeting.

The news comes in the week when the US Food and Drug Administration is scheduled to make a decision on ipilimumab based on another study, 020, which compared the overall survival rate of patients taking the drug plus the vaccine glycoprotein (gp100), just ipilimumab, and gp100 (the control) alone. Those 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.

The FDA put back a decision date around Christmas in order to further assess the data provided by B-MS but analysts believe approval will be forthcoming before the new Prescription Drug User Fee Act action date of March 26. Tim Anderson at Sanford Bernstein issued a research note saying that "ipilimumab is an exciting drug, especially given the dearth of effective therapies for this bad form of cancer".

He added that the drug likely gives a meaningful two-year survival benefit compared with monotherapy and will likely show again that a smaller proportion of patients (some 15%) have a near-cure like response. Mr Anderson is forecasting worldwide ipilimumab sales of around $1.7 billion in 2015.

The drug, a fully human monoclonal antibody that essentially works by boosting the immune system’s T-cell response, has also been associated with severe side effects, such as severe diarrhoea and inflammatory conditions. However, treatment options for patients with advanced melanoma, one of the deadliest forms of cancer, are extremely limited.