Rituximab-based pre-emptive treatment of molecular relapse in follicular and mantle cell lymphoma.

Pre-emptive rituximab (pRTX) might represent an effective approach for patients with follicular (FL) and mantle cell lymphoma (MCL) experiencing molecular relapse (M-rel). However, available experience is still limited. We retrospectively collected FL and MCL cases that underwent pRTX with four weekly rituximab infusions (375 mg/m²) due to molecular persistence or M-rel. M-rel was assessed using nested polymerase chain reaction (PCR) and real-time quantitative PCR using the Bcl-1/IGH, Bcl-2/IGH or the immunoglobulin heavy chain rearrangement. Twenty-three occurrences of M-rel or persistence were treated in 18 patients (nine MCL and nine FL). The pRTX reinduced molecular remission (MR) in 17/23 cases (7/9 FL and 10/14 MCL). The median time to MR reinduction was 4.5 months (range 3-12), and the median duration of the first MR reinduction was 34 months (range 12-72). In five MCL cases, pRTX was used to treat subsequent M-rels, with success in four cases. No clinical relapses were seen within 2 years of successful reinduction of MR. Progression-free survival after pRTX was 64 % at a median follow-up of 6 years. pRTX was feasible and safe and effectively reinduced MR in FL and MCL patients (74 %). Prospective trials are needed to verify the clinical benefit of similar approaches.