The emerging “smart bomb” drug for breast cancer, developed by Roche’s U.S.-based Genentech unit with technology from Waltham, MA-based ImmunoGen (NASDAQ: IMGN), has passed an important clinical trial that could clear the way for this new kind of treatment to reach the U.S. market.
About one out of every three people (32.7 percent) who enrolled in a study of 110 patients had their tumors shrink completely or partially after they got the experimental drug T-DM1, according to findings presented today at the San Antonio Breast Cancer Symposium. Common side effects of fatigue and nausea were considered manageable for a very sick group of patients, whose disease had worsened after an average of seven rounds of chemotherapy and targeted biotech drugs. The most common severe adverse event was a depletion of platelet cells in the blood that help naturally form clots, which was found in 5.5 percent of patients, researchers said.
“We’re thrilled with the clinical data reported today,” said ImmunoGen CEO Dan Junius, in a statement. Seeing one-third of patients experience tumor shrinkage after other options stopped working was “deeply gratifying,” he said. Genentech’s chief medical officer, Hal Barron, characterized the finding as “promising,” in a statement.
This trial carries significance for breast cancer patients, shareholders of both Roche and ImmunoGen, and the biotech industry because of its potential to crack open a new way of developing more potent antibody drugs. T-DM1 is striving to be the first commercially successful “empowered” antibody. It uses the specific tumor-targeting ability of a well-known engineered antibody called trastuzumab, but (here’s the critical difference) it’s loaded with a potent chemical toxin that packs extra tumor-killing punch.
Researchers have tried this idea of making “smart bombs” or “magic bullets” for decades, but efforts have mostly failed. Scientists say it was difficult to link the antibody with the toxin and then deposit the cell-killing agent specifically in the tumor. One drug designed to work this way, Wyeth’s gemtuzumab ozogamicin (Mylotarg), is approved by the FDA, but it has never gained much widespread use or commercial success.
It could be a different story for T-DM1. While only one-fourth of all breast cancer patients have the gene mutation that makes them eligible for this treatment, the business opportunity is still big. The original trastuzumab (Herceptin), without any potent toxin attached, generates more than $5 billion in annual worldwide sales. The supercharged T-DM1 is only being developed in the beginning for the sickest patients, but analysts predict it could be used in earlier stages of therapy, and eventually become an even bigger hit than the original over time. ImmunoGen, which developed technology to link the antibody … Next Page »
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