Rituximab In Combination with High-Dose Dexamethasone: An Effective Treatment Option for Patients with Relapsed/Refractory Chronic Lymphocytic Leukemia
Authors: Doubek Michael , Simkovic Martin , Panovska Anna , Hrudkova Monika , Belada David , Brychtova Yvona , Mayer Jiri , Smolej Lukas 
Published: October 2019

Abstract
Abstract 4629

Background:
Patients with refractory CLL have poor outcome despite currently used salvage treatment. Regimens based on high-dose corticosteroids seem to offer a promising treatment option in this scenario. High-dose methylprenisolone combined with rituximab (R-HDMP) demonstrated significant activity in relapsed/refractory CLL but serious infectious complications occurred in a substantial proportion of patients. Pilot data have shown that combination of dexamethasone and rituximab (R-Dex) may provide comparable results with less toxicity.

Aims and Methods:
We performed a retrospective analysis of the efficacy and safety of R-Dex in patients (pts) with CLL treated at two tertiary centers between April 2006 and February 2010. Patients received two versions of R-Dex regimen: the dose of rituximab was either 500 mg/m2 on day 1, 8, 15, 22 (375 mg/m2 in 1st cycle), repeated every 4 weeks (n=25) or 500 mg/m2 on day 1 (375 mg/m2 in 1st cycle) repeated every 3 weeks (n=16). The dose of dexamethasone was identical in both regimens: 320 mg per cycle (40 mg on day 1–4 and 10–13 or 15–18).

Results:
R-Dex was administered to 41 patients (19 males) with median age of 68 years (range, 44–81) indicated for treatment according to NCI-WG criteria. Autoimmune hemolytic anemia or thrombocytopenia was the only indication for the treatment in 7 patients. Rai stage III/IV was present in 37/41 pts. IgVH genes were unmutated in 24/29 pts with available results. Cytogenetic aberrations detected by FISH (n=33) revealed del 17p in 7 patients; del 11q in 11 patients; del 13q in 15 patients and trisomy 12 in 5 patients. Median number of previous therapies was 2 (0-8); 29/41 pts were previously treated with fludarabine-based regimens. The effect of R-Dex in evaluable patients without hemolysis (n=32) was: overall response rate (ORR), n= 21 (62%), complete remission (CR), n=6 (18%), partial remission (PR), n=15 (44%), stable disease (SD), n=4 (12%) and progressive disease (PD), n=5 (15%). All patients treated with R-Dex for autoimmune cytopenia achieved complete resolution of hemolysis. Grade III or IV toxicity included infections in 13 patients (32%), steroid diabetes in 6 patients (15%) and rituximab infusion-related side effects in 3 patients (7%). At the time of analysis (February 2010), median progression free survival (PFS) was 9 months; median overall survival has not been reached. There was no difference in ORR, PFS or OS between the two versions of R-Dex regimen.

Conclusions:
This pilot study shows that R-Dex is a feasible and effective treatment for relapsed/refractory CLL. In particular, R-Dex appears to be highly effective in CLL with autoimmune cytopenias. However, infectious toxicity remains a serious issue. In addition, long-term disease control can be expected in minority of patients only. Interestingly, higher dose of rituximab per cycle did not result in improved efficacy.
Supported by research project MZO 00179906 from Ministry of Health, Czech Republic, by research grant MSM 0021620808 and by the Czech Leukemia Study Group for Life.

Disclosures:
Smolej: Roche: Honoraria; Bayer-Schering: Honoraria; Genzyme: Honoraria.