Elesclomol, a skin cancer treatment drug, has been granted orphan drug designation by the US Food and Drug Administration (FDA) for the treatment of patients with metastatic melanoma. Elesclomol is being developed under a global collaboration agreement between GlaxoSmithKline (GSK) and Synta Pharmaceuticals.

Orphan drug designation entitles GSK and Synta to seven years of market exclusivity for elesclomol for the treatment of patients with metastatic melanoma. Additional incentives for orphan drug development include tax credits related to development expenses, reduction in FDA user fees and FDA assistance in clinical trial design.

Elesclomol (formerly STA-4783) is an investigational drug that is not approved for any indication in any market at this time.

Orphan drug status is designed to encourage biotechnology and pharmaceutical companies to develop drugs for rare diseases which affect fewer than 200,000 people in the United States. In November 2006 elesclomol received Fast Track designation from the FDA for development in metastatic melanoma.

"We are pleased that the FDA granted elesclomol orphan drug status for the treatment of metastatic melanoma," said Eric Jacobson, M.D., senior vice president and chief medical officer, Synta Pharmaceuticals. "With the incidence of melanoma increasing more rapidly than any other cancer during the past ten years, there is a significant need for innovative therapies such as elesclomol."

Elesclomol is a novel, injectable, investigational drug candidate that is believed to kill cancer cells by elevating oxidative stress levels beyond a breaking point, triggering programmed cell death. This mechanism of action, called oxidative stress induction, represents a novel way of selectively killing cancer cells.

A pivotal phase III clinical trial of elesclomol in combination with paclitaxel in metastatic melanoma (the Symmetrysm trial) was initiated in October 2007 and phase II trials in other indications, and in combination with other agents, are planned.

"Orphan drug status is an acknowledgment of the significant need to develop new therapies for patients with metastatic melanoma, a disease for which there are few treatment options," said Paolo Paoletti, senior vice president, Oncology Medicine Development Centre, GSK. "Through the development of products like elesclomol, GSK Oncology is reaffirming its commitment to address clinical needs in cancer treatment and improve the lives of patients."

In a double-blind, randomised, controlled phase IIb clinical trial in 81 patients with metastatic melanoma, elesclomol in combination with paclitaxel met the primary endpoint, doubling the median time patients survived without their disease progressing, compared to paclitaxel alone (p = 0.035). The most common adverse events in the elesclomol plus paclitaxel group included fatigue, alopecia, constipation, nausea, hypoesthesia, arthralgia, insomnia, diarrhoea, and anaemia.