Shares in ArQule dropped more than 20% before the weekend after the firm and its partner Daiichi Sankyo unveiled disappointing results from a mid-stage trial of their experimental colorectal cancer (CRC) drug tivantinib.

Top-line data from a Phase II study of tivantinib showed that while there was a trend towards prolonging progression free survival (PFS) and improved response rates in patients taking the drug (alongside irinotecan and Eli Lilly/Merck KGaA/Bristol-Myers Squibb's Erbitux [cetuximab]), the differences were not significant.

The trial, which was conducted by Daiichi, involved 122 patients with unresectable CRC and tumours expressing the wild-type form of the KRAS gene, whose disease had progressed despite first-line treatment. 

Patients were randomised to receive 360 milligrams of tivantinib twice daily, plus irinotecan and cetuximab (experimental arm), or placebo plus irinotecan and cetuximab (control arm). 

Analysis of data showed that the primary endpoint of median PFS was 8.3 months in the experimental arm versus 7.3 months in the control arm, while objective response rate - a secondary endpoint - was 45% compared to 33%, respectively. But both results failed to reach statistical significance.

'Encouraged' by data

Nevertheless, Reinhard von Roemeling, Vice President of Clinical Development-Oncology at Daiichi, said his firm remains encouraged by the findings, and plans to "continue discussions with key opinion leaders in the field of CRC to determine how best to proceed with further clinical development of tivantinib in this tumour type.”

ArQule and Daiichi signed a license, co-development and co-commercialisation pact in late 2008 to co-develop tivantinib in the US, Europe, South America and the rest of the world, excluding Japan, China (including Hong Kong), South Korea and Taiwan, where Kyowa Hakko Kirin holds exclusive rights.

The drug has thus far turned in a mixed performance in clinical trials; failing to make the grade in a Phase III study in lung cancer but showing promise - and hitting targets - in a Phase II trial in patients with liver cancer.