UPDATED: T-DM1 survival rate wows as Roche pushes for megablockbuster approval

Investigators behind the big T-DM1 breast cancer program took the lid off the last big data box from its pivotal study this morning, revealing that the armed antibody delivered a 32% reduction in the risk of death among patients in the pivotal Phase III study when compared to the standard-of-care arm. The median overall survival rate for T-DM1 patients hit an impressive 30.9 months, while patients taking a combination of Tykerb and Xeloda achieved a 25.1-month OS rate, putting Roche ($RHHBY)/Genentech and their minority partner ImmunoGen ($IMGN) on track to a near-term U.S. approval.

The success of T-DM1 in late-stage testing is an endorsement of Roche's multibillion-dollar wager on new, targeted and more potent cancer therapies. About half of its $9 billion R&D budget is devoted to cancer drugs, and T-DM1--a pioneering antibody-drug conjugate--is a prime example of the kind of powerhouse marketing punch the pharma giant is aiming for. The Wall Street Journal today cited the drug as one of the pharma giant's most promising cancer therapies, with Perjeta (pertuzumab, approved in June) getting a mention as well. 

"Roche is moving away from Herceptin with successors that are not just an inch better, but much, much better," Vontobel's Andrew Weiss told the Journal.

These days, practically every developer interested in cancer has an ADC in the pipeline, and many of these new programs are bristling with multi-prong attacks on cancer. Roche has already plotted its next step in studying the drug as a frontline therapy for newly diagnosed breast cancer patients as well as for patients with metastatic cancer.

"That would offer a pretty large patient population," notes Dan Junius, the CEO of ImmunoGen, as he reviewed Roche's ambitious development program for T-DM1. Junius tells FierceBiotech that he expects the FDA to accept the application for the treatment this month, with a PDUFA date in February–though he adds that the agency has shown a willingness to accelerate an approval for some cancer drugs. A European OK likely won't arrive for about a year.

Cowen's Simos Simeonidis has laid out a bullish marketing scenario, expecting that Phase III success in the adjuvant and neoadjuvant setting would put T-DM1 on par with Herceptin, a drug that earned $5.4 billion last year. "And since it will probably be priced at a meaningful premium to Herceptin, we think T-DM1 could end up as one of the biggest biotech drugs."

In a note out this morning, the analyst wrote that "We expect T-DM1 to be approved, and we believe that, given the Tykerb and Pertuzumab precedents of priority review, this decision would come by the end of February 2013." 

ImmunoGen has only a tiered, mid-single-digit royalty on T-DM1, but Simeonidis says it's the main prop for the biotech's $1.2 billion valuation. The late-stage data will be presented at the 2012 ESMO confab being held in Vienna. 

- here's the release from Ariad
- read the feature from The Wall Street Journal on Roche

Special Report: T-DM1 (trastuzumab emtansine) – Top 10 Late-Stage Cancer Drugs – 2012