IDEC-C2B8 anti-CD20 (Rituximab) immunotherapy in patients with low-grade non-Hodgkin's lymphoma and lymphoproliferative disorders: evaluation of response on 48 patients

This study focused on the efficacy of IDEC-C2B8 (chimeric anti-CD20) immuno therapy relative to specific subtypes of low-grade lymphoproliferative diso rders/non-Hodgkin's lymphomas (LPD/NIIL). Forty-eight patients with resista nt or relapsed disease completed the IDEC-C2B8 infusion schedule of 375 mg/ m(2)/wk x 4 wk. The LPD/NHL subtypes included: (a) follicular centre cell l ymphoma (FCC) in 22 patients; (b) mantle cell lymphoma (MCL) in 10; (c) 1 d iffuse large cell lymphoma (DLCL); and (d) the category of small lymphocyti c lymphoma/chronic lymphocytic leukaemia (SLL/CLL) and related disorders in 15 patients. No patient obtained a complete remission. Ten patients (21%) achieved partial remission: 6 FCC, 2 MCL, 1 DLCL, and 1 patient from the SL L/CLL group. Twenty-eight patients had stable disease and 10 progressed dur ing immunotherapy. In patients with CLL and MCL in leukaemic phase, there w as no correlation between the marked decrease in circulating neoplastic cel ls following antibody infusions and amelioration of the tumour burden, The results suggest that the subtype of LPD/NHL and the intensity of CD20 on th e tumour cells influence the effectiveness of IDEC-C2B8. The antibody was m ost efficacious against FCC lymphoma. The efficacy (at the dose schedule of 375 mg/m(2)/wk x 4) against MCL and SLL/CLL appeared to be limited. howeve r.