Thursday, December 29, 2011

Five Reasons Why The Ovarian Cancer Avastin Story Is Not Finished

An ovary almost completely
replaced by cancer
As regular Disease Management Care Blog readers may have predicted, the controversial anti-cancer drug Avastin went bust again in two just-published studies (here and here).  This time it wasn't for the questionable treatment of breast cancer but ovarian cancer.  Yet, while the nation's mainstream media has passed sentence on Avastin's failure, the DMCB isn't quite ready to "short" the drug.

Very briefly, one randomized prospective trial involved women with high risk or disease that had spread.  Participants were randomly assigned to standard chemotherapy plus Avastin, while the other group got just the chemotherapy.  Women in the Avastin group went 24.1 months without progression of their disease versus 22.4 months in the non-Avastin group.  Death rates are still being analyzed.

The other trial involved women with cancer that had spread.  They were randomly assigned to one of three groups: just 1) chemotherapy or 2) chemo plus either Avastin in the earlier cycles of chemotherapy or 3) Avastin with all the cycles of chemotherapy.  The just chemo group went a median of 10.3 months before there was disease progression, while the Avastin groups went 11.2 and 14.1 months, respectively.

Even with the depressing results outlined above, the DMCB has several reasons for believing that we've not seen the last of Avastin for ovarian cancer.  Much of the DMCB's obstinacy has to do with the complexities of cancer treatment and how statistics are collected and interpreted:

1.  The trials involved patients with aggressive or advanced disease. Much like the logic of using a small extinguisher on a huge house fire, that doesn't mean that persons with limited or microscopic disease wouldn't be helped by Avastin.  The only way to find out is to perform the same sorts of randomized trials involving patients with less widespread or aggressive disease. 

2.  It's possible that some of the Avastin patients may have gotten much better, but their positive results were diluted by the majority of the patients who didn't benefit. In other words, the clinical trials report the average response rate.  That does little to answer the two questions that every individual cancer patient asks: 1) are there exceptions and 2) am I one of them?

3. Assuming exceptions exist, there may be a way to identify that small minority of patients who are more likely to derive a greater benefit from Avastin. Assuming ovarian cancer is a heterogeneous disease, there may be a blood test or an additional type of biopsy that can answer the two questions above.

4. "Disease progression" is just one of several cancer outcomes.  While it's important, there are others that may have more meaning for patients and could simultaneously put Avastin in a better light.  As a reminder, death rates in one of the trials described above are still being compiled and have yet to be reported.  Stay tuned.

5. Last but not least, the most selectively generous interpretation of the data above is that Avastin helped patients go an additional 4 months before their disease started spreading again.  While that may not seem worth it, the DMCB has taken care of plenty of patients who would think it's plenty worth it.  While commercial insurers will have every reason to question payment for a horrendously expensive drug with only 4 months of benefit, patients and their doctors will argue that hope is "medically necessary."

Image from Wikipedia

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