Gilead Sciences has made its first foray into oncology and filed its eagerly-anticipated drug idelalisib with regulators in the USA.

The company, best-known for its HIV/AIDS treatments, has submitted a New Drug Application to the US Food and Drug Administration for idelalisib, a targeted, oral inhibitor of PI3K delta, for the treatment of indolent non-Hodgkin’s lymphoma (iNHL). Specifically, the company says the data submitted in the NDA support the use of idelalisib for patients with iNHL that do not respond to Roche and Biogen Idec’s blockbuster Rituxan (rituximab) and to alkylating-agent-containing chemotherapy.

Most iNHL patients are diagnosed at an advanced stage of disease, and median survival from time of initial diagnosis for patients with the most common form of iNHL, follicular lymphoma, is eight to 10 years. Gilead notes that “the outlook for refractory iNHL patients is significantly poorer”.

The NDA is supported by data from a Phase II study of 125 patients with treatment-resistant  iNHL and those on single-agent idelalisib achieved an overall response rate of 53.6%, with a median response of 11.9 months. Median progression-free survival for all patients was 11.4 months, while 89% experienced lymph node shrinkage.

Updated results from this study were included in the NDA filing and have also been submitted for presentation at an upcoming scientific conference. Gilead plans to file idelalisib in the European Union in the fourth quarter.