Revlimid and Second Primary Cancers

Newly-diagnosed patients:

Last Monday, May 7, 2012, the FDA issued a Drug Safety Communication which says, in part, "in clinical trials of patients newly diagnosed with multiple myeloma, those patients treated with Revlimid had an increased risk of developing new cancers." These are also called "second primary cancers."

If you are considering Revlimid as initial treatment or as a maintenance treatment, you may wish to read on before you lean very heavily on that FDA statement:

• The FDA statement contains no new information. The facts on which the statement is based are from three well-known studies on newly-diagnosed patients, and are over a year old. If your doctor doesn't already know of these studies, it's time to get a new doctor.
  
  
• Since one year ago, new information about those studies has been made available, and it is not clear to me that the FDA used that information.
  
  
• The three studies are all different, with somewhat different objectives, and none was specifically designed to reveal the frequency of second primary cancers. They were meant to show the difference in progression-free survival and overall survival, comparing Revlimid maintenance with a placebo, after transplant or other initial treatment.  The Myeloma Beacon has a good description of the three studies.
  
  
• Analysis by FDA and others may be wrong, and this may be one reason:
  • All three studies demonstrated that Revlimid maintenance does extend the time to relapse.
  • In some cases the patients on maintenance had twice as much time, or even more, before relapse.
  • Therefore, patients on Revlimid maintenance had much more time to develop second cancers before relapse than did patients on the placebo.
  • It appears that some of the studies, if not all three, stopped looking for second primary cancers once a patient had relapsed.
  • Thus, we would expect patients in the Revlimid arm to collect more second primary cancers, just because they had more time to do so.
  
  
• Even if Revlimid treatment did result in more second primary cancers, that risk may be lower than the risks from not taking it.

Patients with relapsed/refractory myeloma:

The FDA also reviewed results from two clinical trials which supported the initial FDA approval of Revlimid. I find their description of the data to be confusing at best, but in the worst interpretation of it, patients on Revlimid with high-dose dexamethasone experienced fewer than four second primary cancers per 100 patients per year.

Bottom line:

I'm not a doctor, but I have opinions anyway, and in my opinion, the FDA Safety Communication should not be an occasion to change any decisions about using Revlimid, which is still one of the best treatment options available. Other very smart doctors are trying to make sense of this issue as we speak, and we should wait until better information is available.

I admit to a little bias on this issue, because: (1) I take pomalidomide continuously. It is a close relative to Revlimid, and I don't want to think about second primary cancers from that; and (2) I like Celgene, the makers of both drugs. However, I really don't think that we have enough information yet to even say for sure that Revlimid poses a greater risk of second primary cancers than no treatment at all.

Please comment, especially if you have any corrections or suggestions about facts or reasoning in this blog post. Please let me know. Thanks.