Study to Evaluate the Association Between Lenalidomide and Tumor Flare Reactions and High Tumor Burden in Patients with Relapsed or Refractory Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is a rare form of lymphoma in which certain white blood cells—B cells—undergo malignant changes. In most cases, the disease progresses slowly; however, some patients have an aggressive subtype that requires more intensive treatment. Standard treatments include chemotherapy, immunotherapy, and stem cell transplantation, but in some patients, the disease returns after treatment or no longer responds to it. Lenalidomide, also known by the brand name Revlimid, is a medication that supports the immune system and inhibits the growth of cancer cells. It is commonly used today in the treatment of recurrent or treatment-refractory cases of MCL. This study investigates the relationship between lenalidomide and the so-called tumor flare reaction (TFR) and overall tumor burden in patients with relapsed or refractory MCL. A tumor flare reaction is a temporary worsening of tumor-related symptoms after the start of treatment, which can sometimes be difficult to distinguish from disease progression. Tumor burden refers to the number of cancer cells in the body. The study design is non-interventional and retrospective, meaning that existing data from patients who have received lenalidomide will be analyzed. No new drug or treatment will be tested in the study; it is purely observational. Data are being collected from various European clinics that have used lenalidomide in MCL patients to investigate the frequency and characteristics of TFR and tumor burden. Eligible participants are adults who have received at least one dose of lenalidomide as part of their MCL treatment.