Efficacy of ⁹⁰Y-Ibritumomab Tiuxetan (Zevalin) in Refractory or Relapsed MALT Gastric Non Hodgkin’s Lymphoma.

Radio-immunotherapy (RIT) is an effective approach for patients with relapse-refractory NHL. The aim of RIT is to use the monoclonal antibody to target radiation to the tumor bulk while limiting exposure of normal tissues. Toxicity is prevalently hematologic, but transient and reversible. Zevalin in particular has demonstrated activity in follicular (FL) and diffuse large B-cell (DLBC) NHL, but data are still lacking in MALT NHL. In this setting of pts Zevalin could offer an alternative option to those pts who relapse or do not respond to conventional treatment. We report efficacy results of a pilot study of Zevalin delivered at conventional activity (0,4 mCi/kg) in gastric NHL pts resistant or refractory to conventional systemic treatment. From May 2004 to January 2006, 7 patients were enrolled. They all had gastric resistant-refractory CD-20 positive B-cell NHL: 2 DLBC and 5 MALT. Median age was 57 ys (range 36–64), 3 female and 4 male. At time of treatment 5 out of 7 patients had stage I/IIA (MALT), while 2 out of 7 pts had stage III/IV (DLBCL) of disease. Helicobacter Pylori was negative in all pts at time of treatment, positive at diagnosis in 3 out of 5 pts affected by MALT gastric NHL. Median number of previous therapies received was 2 (1–4): all of them had received prior CT, 3 prior Rituximab, no one had received prior RT. Toxicities were primarily haematological, as expected, and reversible. Response evaluation was performed two months after Zevalin administration by upper gastrointestinal endoscopy with multiple biopsy and endoscopic ultrasonography. All patients are now evaluable for response: 5 CR (all MALT), 2 PD (both DLBC NHL). All responders still maintain a CR at 27, 20, 16, 9 and 8 months after treatment.

Conclusions: Zevalin seems to be very active in pts with MALT gastric NHL resistant or refractory to conventional systemic treatment. Its mechanism of action mimics conventional RT already known as valid option in MALT gastric NHL. If these preliminary results are confirmed in larger number of pts, one single administration of Zevalin delivered at conventional activity (0,4 mCi/kg) could be considered a possible alternative option in the treatment of such indolent disease.