The U.S. Food and Drug Administration (FDA) announced last Friday that it is investigating the safety of Revlimid, a drug used in the treatment of myelodysplastic syndromes.

The investigation was prompted after results from clinical trials conducted in patients with the blood cancer multiple myeloma suggested that Revlimid (lenalidomide) may increase the risk of developing new types of cancers in patients taking the drug for extended periods of time.

Since Revlimid is approved to treat multiple myeloma as well as myelodysplastic syndromes (MDS), the FDA is investigating Revlimid’s safety when used for either disease.

The FDA is also reviewing the safety of thalidomide (Thalomid), since thalidomide is chemically similar to Revlimid. It is standard procedure for the FDA to investigate related compounds if the safety of one is in question. However, no studies have suggested that thalidomide may be linked to higher rates of new cancers. 

Once a drug is approved by the FDA, safety reviews are not common.  However, the FDA continues to monitor all drugs after their approval, and it will investigate the safety of a drug if any data emerge suggesting that the drug may not be as safe as believed when it was first approved.

Despite the safety investigation, the FDA stated in its announcement that it currently believes “the benefits of Revlimid continue to outweigh the potential risks.”

Safety reviews are typically conducted by FDA staff, who may consult with temporary Special Government Employees, members of the Oncologic Drugs Advisory Committee (ODAC), and potentially other individuals without conflicts of interest if they are needed to understand the data and situation at hand.  The ODAC is the committee of outside scientific experts that advises the FDA in regard to the approval of new oncology drugs and changes to the approved use of already marketed oncology drugs.

Findings from the safety review are expected within a few months, since the FDA may be waiting for data from some of the ongoing clinical trials in order to complete its review.

Once the review has been completed, the FDA may conclude that there is no safety problem, that further investigation is needed, or the agency can modify the prescribing information or the approved uses of Revlimid and thalidomide. 

Although it is theoretically possible that the FDA could revoke its approval for the sale and use of Revlimid or thalidomide, these drugs have demonstrated clear benefits for MDS and multiple myeloma patients, so such an outcome is considered highly unlikely. 

If a link is found between Revlimid or thalidomide and secondary cancers, a warning could be placed on their official prescribing information or a cap might be placed on the length of time they are recommended to be used.

The FDA will communicate the results of the investigation and any new recommendations once it has completed its review.

In the meantime, the FDA recommends that patients who are currently taking Revlimid should continue taking the drug as prescribed by their physician and discuss any questions or concerns with their physician.

For more information, please see the FDA announcement or the coverage on The Myeloma Beacon.

The MDS Beacon will publish a follow-up article later this week that will provide further information on Revlimid’s safety concerns.