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Caring Currents

Is TDM-1 a Miracle Drug for Advanced Breast Cancer?

By , Caring.com senior editor
Last updated: December 20, 2009
Smack in the middle
Image by ogimogi used under the creative commons attribution license.

Breast cancer that's HER2-positive can be particularly aggressive, and HER2-positive breast cancer tends to strike women at younger ages and be diagnosed at later stages, making for some sad stories. This is the type of cancer I've been helping a close friend go through treatment for, so I know just how scary the diagnosis can be.

Happily, the targeted therapy Herceptin has made treatment for the approximately 30 percent of patients whose cancer is HER2-positive much more effective than in years past. But there are women for whom Herceptin -- along with a whole host of other treatment regimens -- either doesn't work or stops working. These tend to be tough cases, and patients run out of options.

But this week there was big news for HER2-positive women: a dramatic announcement about T-DM1, an experimental drug that's been in clinical trials since January. Known colloquially as "super Herceptin" by the women taking it, T-DMI is an unusual joint project between two companies, Genentech, which makes the targeted antibody trastuzumab, (Herceptin), and ImmunoGen, which contributed it's cancer-killing agent DM1.

Oncologists don't like the term "miracle drug," and try not to use it -- but the word miracle was in fact used when researchers presented results of a Phase II trial of T-DM1 at the Breast Cancer Symposium in San Antonio, Texas, last Tuesday.

Oncologists seem certain that T-DM1 (hopefully it will get a better name!) will now be fast-tracked by the FDA, and the rapid expansion and loosening of the trials suggests that nearly everyone Cancer is united in wanting to get this drug out to the women who need it as quickly as possible.

What it is: T-DM1 is a 2-in-1 "Trojan Horse" therapy in which Herceptin zeroes in on the cancer cells and delivers a chemotherapy agent that stops cancer cell division.

Who it's for: Women with Stage 3 or Stage 4 (metastatic) breast cancer that's HER2-positive and resistant to previous treatment methods. The women in the Phase II trials had undergone an average of seven previous drug regimens, including Herceptin.

In other words, T-DM1 is for those who truly need a miracle; and they may finally get one.

The results: Almost half the women in the trials (45 percent) had a positive response, which was defined essentially as a halt to tumor growth. In other words, the drug stopped rapidly progressing cancer from progressing. And in 33 percent of the patients, their tumors shrank. This is in a population that had run out of options and whose tumors had not responded to previous drugs.

As you can imagine, for women who are running out of time and options, their families, friends, and loved ones, this is big news, and -- as a result -- the [Breast Cancer message boards] (http://community.breastcancer.org/forum/8/topic/728426?page=1) started lighting up as soon as word got out.

How to get TDM-1: To get this still-experimental drug, you have to enroll in a clinical trial, though I have heard that some doctors are prescribing it under the rule known as "compassionate use", which allows a seriously ill patient to use a new, unapproved drug when no other treatment is available.

To find an open trial near you, read through this list of recruiting trials maintained by Clinicaltrials.gov, the government's clinical trials database.

There are many different T-DM1 trials ongoing, with differing criteria for admittance, so to stay current and get a comprehensive sense of what's available, you should also do your own search on www.clinicaltrials.gov.

To end on a positive note, and to give you a sense of how exciting these results have been, researchers have created an "extension" study for T-DM1 that essentially allows cancer patients who've been in the trials to continue on the drug indefinitely.

Usually a trial continues for a set period of time, then is terminated so the researchers can process and study the results. But to make sure no one gets kicked off T-DM1 they created this extension trial "by invitation only" which just means your doctor recommends that you stay on the drug.

While just shy of half the women who tried T-DM1 got results, there are a number of "miracle" stories, too: women who were given six months or less to live who've now been on T-DM1 for 10 months or more (most of the trials started in January) and are celebrating positive scan results.

So go, you brave T-DM1 gals; I'm thrilled for you and the families who love and need you, and excited to spread the word about something that's giving metastatic breast cancer patients hope for the future.