The purpose of this study is to see if iberdomide is a safe and effective maintenance therapy option for people with multiple myeloma (MM) who have had an autologous hematopoietic stem cell transplant (AHCT) and have already received lenalidomide as maintenance therapy.
   
The study drug iberdomide is designed to target and destroy proteins that produce myeloma cancer cells. By destroying these proteins, iberdomide may prevent the cancer from returning or getting worse. This research study is being done because currently there is no effective treatment for this type of condition.
   
The U.S. Food and Drug Administration (FDA) has not approved iberdomide for the treatment of MM or any other condition and the use of iberdomide in this study is considered investigational.

There are two study groups. Group 1 is for participants who had an AHCT no more than 12 months ago and started maintenance therapy with lenalidomide at least 6 months ago. Group 2 is for participants who had an AHCT within 2-6 months and received 1-3 past therapies, including lenalidomide maintenance therapy.

Participants in both groups will receive the study drug regimen with iberdomide. However, participants in Group 1 will get a slightly lower dose. The study team will discuss dosing with each participant.

Total study participation will last approximately 1 year.