Boehringer to start new Phase III study of Tovok

* Aims to show benefit for patients with EGFR mutation

* Targets same lung-cancer market as AstraZeneca's Iressa

* Two further Phase III trials ongoing

FRANKFURT, Aug 3 (Reuters) - Boehringer Ingelheim is starting a new Phase III trial of its lung-cancer drug Tovok to show the pill works in patients whose tumours have undergone a certain gene mutation, the company said on Monday.

Privately held Boehringer is trying to establish Tovok as an initial treatment for non-small cell lung cancer patients (NSCLC) whose tumours show a mutation of the so-called EGF receptors on the surface of tumour cells, targeting the same market as AstraZeneca's (AZN.L) Iressa.

Iressa last month won approval in Europe for use in the 10 to 15 percent of lung cancer patients whose tumours had undergone the EGFR gene mutation, reviving the fortunes of a product which had largely been written off by industry analysts.

Boehringer, Germany's second-largest drugmaker, said it would compare the efficacy and safety of Tovok, based on the active ingredient BIBW 2992, to that of standard chemotherapy of cisplatin and pemetrexed.

The company is currently testing Tovok in two further Phase III trials.

Tovok and Iressa could also pose a threat to Tarceva, another oral lung cancer treatment from OSI Pharmaceuticals Inc OSIP.O and Roche Holding AG (ROG.VX).

Three phases of testing are generally required for regulatory approval. (Reporting by Ludwig Burger; Editing by David Holmes)