Breast Cancer “Smart Bomb” From Roche, ImmunoGen Shows Tumor Shrinkage in Big Test

12/9/09Follow @xconomy

The “smart bomb” drug for breast cancer from Roche and Waltham, MA-based ImmunoGen looks to have passed an important test.

Full data aren’t being released yet, but ImmunoGen (NASDAQ: IMGN) today disclosed an interesting tidbit in a regulatory filing on its new version of trastuzumab (marketed as Herceptin) that combines an antibody with a toxin to give it more potency against breast cancer. The drug, T-DM1, caused tumors to at least partially shrink for about one-third of patients (32.7 percent) whose disease worsened after treatment with the regular version of trastuzumab and a competitor, lapatinib (Tykerb). This was an early peek at results from a 110-patient clinical trial that will be presented this weekend at the San Antonio Breast Cancer Symposium.

The filing doesn’t provide any detail on the side effect profile of the drug, how long the patients stayed in remission after getting the drug, or whether they actually lived longer than they otherwise would with standard treatment. But tumor shrinkage was the main goal of the study and this looks like the compelling data that ImmunoGen and Roche were hoping for, which I described in a preview story on Monday. Another trial of 112 patients presented earlier this year found that tumors shrank for about one-fourth of patients on T-DM1, without the heart-damaging side effect that’s been observed with the older version of trastuzumab. If these new results are compelling enough, ImmunoGen CEO Dan Junius told me, they could prompt Roche to seek FDA approval for the new drug in 2010, without having to wait for results from a bigger study of 580 patients, which started in February.

ImmunoGen isn’t commenting on the latest tidbit of data, preferring to wait until the full results are reported in San Antonio this weekend. But shareholders liked the news. Shares of ImmunoGen climbed 3 percent to $8.43 at 1:45 pm Eastern after the regulatory filing crossed the wire.

Krysta Pellegrino, a spokeswoman for the Genentech unit of Roche, says more details on the trial are expected out at 7 am Central time on Saturday in San Antonio. She couldn’t comment further.

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  • Wade Roush

    Luke, from one Xconomy colleague to another, nice story. Thanks.

    Dumb question, but is tumor shrinkage the most important outcome measure for a breast cancer drug?

  • http://www.xconomy.com/author/ltimmerman/ Luke Timmerman

    Wade–it’s not a dumb question at all. Tumor shrinkage is really a surrogate endpoint, which you could look at as essentially a quick and dirty measurement that’s supposed to predict whether a drug is actually reaching the gold standard of survival. Sometimes tumors bounce back after they shrink, and people end up dying in the same amount of time. But many cancer studies are designed to assess tumor shrinkage because that can provide a relatively quick indication of whether the drug is working. Depending on the type of disease, FDA will sometimes accept this as good enough evidence for approval, but in some cases they will insist on survival time as the primary endpoint.

  • Wade Roush

    Interesting. It also seems to me that a tumor’s size wouldn’t necessarily be the only measure of how dangerous it is….its location and whether it’s likely to metastasize would be just as important, no? But I don’t know how you measure those things in a drug study.

  • http://www.xconomy.com/author/ltimmerman/ Luke Timmerman

    That’s another good point. There’s another endpoint the FDA likes, which is unfortunately named “progression-free survival” or PFS. This basically measures how long patients remain stable without their disease metastasizing, or progressing, after they get the drug. I’m sure you can find plenty of people who will argue about whether it’s a more reliable predictor of overall survival time than tumor shrinkage, but it’s not perfect either. Depending
    on the study, patients come in periodically to get a CT scan or some other image taken to see if they have any more metastases.

    This might seem like an arcane academic debate, but it’s actually really important to how cancer drugs get developed. Surrogate endpoints are needed because there’s no other way to get a practical answer for some cancer drugs, in which you might need to wait 5 or 10 years to see whether a drug actually helps people live longer, which is way too long for most biotech companies to wait around.

    Even so, it’s totally appropriate to be skeptical of surrogates—especially ones that haven’t stood up to the test of time. Some of the blood biomarkers that get a lot of attention in the lab will need lots of long term follow up to really validate whether they are truly predictive of better survival outcomes. That’s one thing to remember when people talk them up as the basis for personalized medicine.

  • http://www.BiotechStockResearch.com David Miller

    Tumor shrinkage can be an endpoint all its own, even with no confirmation of survival, in this late-stage patient population for whom there is no approved therapy. These patients have failed Herceptin and Tykerb and really have nothing left.

    Luke is right (as usual!) tumor shrinkage varies in approvability depending on the disease and especially the stage.

    Wade – Companies are looking at how to determine whether a tumor is a risk to spread or not. Circulating tumor cells could be one measure and the FDA has approved some tests there. Most docs think shrinkage takes care of that question, but that’s not true in all cancers. Despite that, shrinkage regardless of location of tumor or chance to spread is what’s measured and accepted by the FDA.

  • John

    If the results are good why were they only chosen for a poster presentation early in the morning?

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