Bendamustine-induced rash is associated with a favorable prognosis in patients with indolent B-cell lymphoma.

Bendamustine is now recognized as a key drug for indolent B-cell lymphoma (iBCL), mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL). Skin toxicity associated with bendamustine is one of the characteristic adverse effects. We retrospectively examined the relationship between bendamustine-associated drug rashes and disease prognosis of iBCL and MCL at our institution. Between January 2011 and August 2019, 65 patients (39 men and 26 women, median age 68, range 41-84 years) were treated with bendamustine alone (n=11, 120 mg/m² on days 1 and 2) or a combination of rituximab and bendamustine (n=54, 90 mg/m² on days 1 and 2). Of these patients, 47 had follicular lymphoma (FL), 10 had MCL and 8 had other iBCLs. Drug rash occurred in 27 (41.5%). Eight cases (29.6%) were grade 1, 5 (18.5%) were grade 2 and 14 (51.9%) were grade 3. The onset was in the first course in 17 (63.0%), 2nd course in 5 (18.5%), 3rd course in 2 (7.4%), 4th course in 1 (3.7%) and 5th course in 2 (7.4%). No treatment was administered in 1 case (3.7%), topical steroid was applied in 10 (37.0%), antiallergic drug was administered in 2 (7.4%), topical steroid and antiallergic drug were administered in 5 (18.5%), and oral and topical steroid and antiallergic drug were administered in 9 (33.3%). The 3-year progression-free survival (PFS) and overall survival (OS) in patients with rash development were 80.0% and 85.5%, respectively, and those in patients without development were 36.4% and 54.0%, respectively (p=0.009 and 0.02, respectively). By multivariate analysis, the development of rash was associated with a better PFS and a diagnosis of iBCL was associated with a better OS. This study revealed that bendamustine-induced rash is associated with a favorable prognosis among patients with iBCL.