A Retrospective Analysis of Response to High Dose Rituximab Monotherapy in CLL/NHL Patients Who Received Prior Standard Dose Rituximab Therapy.

Background: Rituximab at standard dose (375 mg/m²) in combination with chemotherapy has been used to treat CLL and NHL. We retrospectively evaluated the response and toxicity of high dose rituximab (HDR) (500 mg/m² thrice weekly for 2 weeks, total dose 3 gm/m²) in patients with CLL or NHL, who had received prior treatment with standard rituximab as either monotherapy or in combination chemotherapy, to determine if there was a dose response relationship.

Methods: Eight patients with either CLL or NHL who had received HDR therapy were evaluated. Patients received HDR because they refused conventional treatment or failed to respond to prior combination chemotherapy. Seven of the patients had prior combination therapy, whereas 1 had received standard dose rituximab alone. Response to HDR was evaluated based upon absolute lymphocyte count approximately 21 days after the final treatment in CLL patients and PET/CT scan after the final treatment for NHL.

Results: Mean age at treatment: 70 yrs (range = 57–83), males (n=7) and female (n=1), CLL (n=5) and NHL (n=3). One patient with CLL had Richter’s transformation. Patients received prior treatments with rituxan alone (n=1), combination therapy for CLL with FCR, FR or PCR (n=5) or combination therapy for NHL with hyperCVAD-R, CHOP-R or RICE (n=2). Of the 5 patients with CLL treated with HDR, 3 achieved partial remission (PR) while the remaining 2 patients developed progressive disease. Complete remission, however, could not be assessed secondary to lack of a post treatment bone marrow biopsy. All 3 patients with NHL developed progressive disease. One patient developed rigors during the infusion of HDR requiring IV steroids. No infusion was stopped secondary to toxicity.

Conclusions: Based upon our findings, HDR was active in patients with relapsed CLL but not in relapsed NHL. Further exploration of this dose-response relationship is warranted in patients with CLL.