Experimental Cancer Drug Tarceva

NEW YORK (Reuters Health) - OSI Pharmaceuticals Inc. is more confident than ever of the potential of its experimental cancer drug Tarceva (erlotinib HCl), even after the failure of a similar drug in a major clinical study this summer, OSI Chairman and CEO Dr. Colin Goddard told investors at the UBS Warburg Global Life Sciences conference here on Wednesday.

In August, AstraZeneca Plc. announced that adding its investigational non-small cell lung cancer (NSCLC) drug Iressa to standard therapy did not improve survival in a phase III trial of patients who had failed prior chemotherapy. The news raised concerns about a new class of cancer drugs expected to be effective with fewer side effects than other therapies.

Iressa is an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor. These kinds of drugs are believed to cause fewer adverse events because they target specific proteins associated only with tumors.

Since Tarceva is also an EGFR inhibitor, many industry watchers began to worry that the drug, which is still being evaluated in a phase III trial of NSCLC patients, might also fail to meet expectations.

But Dr. Goddard dismissed these concerns on Wednesday, noting that while similar, Iressa and Tarceva are structurally different. But more importantly, he said, the companies' approaches in evaluating their respective drugs are very different, as well.

Dr. Goddard told Reuters Health that in its failed trial, AstraZeneca was using doses of Iressa one-third to two-thirds of the maximum tolerable dose. OSI is using the highest tolerated dose of Tarceva.

Interestingly, he said, one of the side effects of Tarceva treatment is rash, and "what we find is when we produce rash, patients tend to do very well. In other words, there's a suggestion that pushing dose has real benefit in terms of survival."

"Hence, our whole rationale and belief is that we will see a differentiation between [Iressa and Tarceva] on the basis of that [dosing] strategy."

The OSI study is expected to complete patient accrual by the end of the year. Dr. Goddard said that OSI expects Tarceva to receive a six-month priority review by the US Food and Drug Administration after it is submitted.