Seattle Genetics & ImmunoGen on a Roll

The good news keeps coming for companies developing antibody-drug conjugates, which enable the targeted delivery of powerful chemo drugs. (click here for more info on how they work). On the clinical side, ImmunoGen and Roche have released a promising set of data for T-DM1, their drug linking trastuzumab with DM1, a derivative of the microtubule-disrupting agent maytansine, while Seattle Genetics and Millennium Pharmaceuticals offered the latest validation for SGN-35. Meanwhile, ImmunoGen sealed a deal with Novartis worth up to $240 million.
First to the clinical results: Although the trial was relatively small, ImmunoGen’s T-DM1 appeared to be as good at shrinking tumors as a combination of Herceptin and chemotherapy in patients with HER-2 positive, metastatic breast cancer. Importantly, patients in the T-DM1 arm experience significantly milder side effects than those taking the Herceptin/chemo combo. For example, 66.2% of patients in the chemo arm experienced complete hair loss, compared to 1.5% in the T-DM1 arm, and 57.4% of the Herceptin/chemo patients experienced neutropenia, or white blood cell count lowering, vs. 7.5% of the patients in the T-DM1 arm.
In a note to investors, RBC Capital Markets’ analyst Jason Cantor called the results “particularly groundbreaking” because no chemotherapy drug was added into the T-DM1 treatment arm. The trial “is significant validation of ImmunoGen’s technology and antibody-drug conjugation technology, in general.”
In August, ImmmunoGen and Roche had a setback when after FDA refused to accept their biologics license application for T-DM1 based on the Phase II data offered up in the filing. Roche had already started a Phase III study, and Cantor expects Roche to try again with FDA in mid-2012, putting a potential launch in the first half of 2013.
The positive data for T-DM1 comes on the heels of strong results for Seattle Genetics’ antibody-drug conjugate, SGN-35. Last month, the Seattle-based biotech said the drug was able to shrink tumors in 75% of people with Hodgkin’s lymphoma who had failed to see results with other treatments. Seattle Genetics expects to file a BLA for SGN-35 in the first half of 2011, with approval expected in the second half of the year.
Today, Seattle Genetics and Millennium said that SGN-35 shrank all or some tumors in 86% of patients with anaplastic large-cell lymphoma. Look for more data in both Hodgkin’s lymphoma and in ALCL in December during the American Society of Hematology annual meeting.
On the deal front, Novartis is coughing up $45 million upfront and up to $200 million in milestones to apply ImmunoGen’s antibody-drug conjugate technology (which it calls “TAP” for targeted antibody payload) to a select number of targets. ImmunoGen could also score research funding and additional support if it performs manufacturing for Novartis.

Author: Lisa Jarvis

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