Cyclophosphamide, Adriamycin, Vincristine and Prednisone Plus Rituximab (CHOP-R) in Fludarabine (F) Refractory Chronic Lymphocytic Leukemia (CLL) or CLL with Autoimmune Cytopenia (AIC) or Richter's Transformation (RT): Final Analysis of a Phase II Study of the German CLL Study Group

In the last decade, important progress has been achieved in the treatment of CLL through the use of purine analog-based chemoimmunotherapies. Several conditions remain a challenge, often with a poor outcome. Amongst these therapeutic problems are Richter's transformation (RT), refractoriness to F-based therapies (Fref), and the occurrence of AIC, which are sometimes induced by F. Fref and RT pts have a very poor prognosis with an estimated overall survival (OS) of only 10 and 8 months (mos), respectively. Therefore, therapeutic alternatives are urgently warranted. CHOP-R has improved the outcome of pts with aggressive non-Hodgkin's lymphoma. To test the efficacy and tolerability of the CHOP-R regimen in CLL patients with RT, Fref, or AIC, the GCLLSG initiated a prospective phase II trial.

Material and Methods: 62 patients were included in the study. Due to protocol violations, 2 patients were excluded. Within the group of Fref pts, the medical review detected 11 patients who had received pre-treatment with F (Fpret), but were not refractory according to the updated guidelines (Hallek et al., Blood 2008). Thus, 26 pts were classified as Fref/pret, 19 pts as AIC and 15 pts as RT. All patients received CHOP every 3 weeks (cyclophosphamide 750mg/m², adriamycin 50mg/m² and vincristine 1, 4mg/m² d1; prednisone 100mg/m² d1–5). Rituximab was added starting with the 2nd cycle (375mg/m² on each d0, and 21 days after the last CHOP-R). RT pts received up to 8, Fref/pret and AIC up to 6 courses of CHOP-R. In case of PD after 3 cycles, pts went off-study. The primary endpoints were remission rate, quality and duration of response.

79%, 73%, and 40% of AIC, Fref/pret, and RT pts were male, respectively. The median age was 65 years (y) for Fref/pret-pts, 66y in the AIC and 69y in the RT group. Binet stages for Fref/pret pts were: A: 8%; B: 27% C: 65 %. All but 3 AIC pts were at Binet stage C. Initial RT stages according to Ann Arbor were: II: 13%, III: 13%, IV 73%. The median number of previous therapies were 3 for Fref/pret, 2 for AIC and 2 for RT.

A total of 314 cycles were administered, with a median number of 3 cycles for AIC and Fref pts and a median number of 4 cycles for the RT group. Due to toxicity 73% of cycles in the Fref/pret group, 66% in the AIC and 87% in the RT group were dose-reduced. 69% of Fref/pret-pts and 58% of AIC-pts received full 6 cycles of therapy and only 40% of RT-pts completed 8 cycles of therapy. Treatment was stopped in 6 pts because of PD. Due to treatment related toxicity treatment was stopped in 16 pts (27%). Treatment related mortality was 3% (2 pts). Treatment toxicity was reported according to NCI common toxicity criteria (CTC) version 2.0. Adverse events grade 3 or 4 for anemia, neutropenia and thrombocytopenia were documented in 75%, 55% and 65% of patients, respectively. Infections were the most common non-hematologic toxicity and occurred in 67%; severe infections CTC grade 3 or 4 occurred in 28%.

All 26 Fref/pret-pts were available for response evaluation. CHOP-R achieved 54% PR, 35% SD and 12% PD. The median progression-free survival (PFS) and median treatment-free survival (TFS) were 11 and 14 mos. OS was 27 mos with a significant difference concerning F-ref (n=15) and F-pret (n=11) pts (17 vs. 35m; p=0.05). We evaluated the response of all 15 RT-pts with 60% PR, 7% CR, 13% SD and 20% PD. The PFS was 15 mos, TFS was 17 mos and OS 27 mos. 17 AIC pts were available for response evaluation with 82% PR, 6% SD and 12% PD. The PFS and TFS were only 14 and 16 mos. The OS was 50 mos.

The population had a high incidence of unfavourable genetic markers: deletion of chromosome 17p [del(17p)] was detected in 24%, del(11q) in 34% and unmutated IGHV in 70%. 85% had high levels of serum thymidine kinase (sTK > 10 U/l), and 49% had high levels of ß2-microglobulin (ß2M > 3.5 mg/l). Patients with del(17p) had an unfavourable response rate and achieved significant less a PR or CR (36% vs. 76%; p=0.03). Multivariate analyses showed that del(17p) and ECOG performance status had a negative prognostic impact on OS (p<0.0001). Moreover the presence of a del(17p) predicted a short PFS (6 vs. 16.9 mos; p=0.001).

CHOP-R achieves promising response rates in CLL patients with Fref and RT and very good response rates in patients with AIC. However, the progression-free survival and overall survival remain unsatisfactory. Therefore, CHOP-R might be used as induction therapy prior to allogeneic stem cell transplantation in physically fit patients.

Eichhorst:Hoffmann La Roche: Honoraria, Research Funding, Travel Grants; Mundipharma: Research Funding, Travel Grants; Gilead: Consultancy. Dreyling:Roche: Research Funding, Scientific advisory board, Speakers Bureau. Bergmann:Celgene: Honoraria. Stilgenbauer:Hoffmann La Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Travel Grants. Fink:Hoffmann La Roche: travel grants. Fischer:Hoffmann La Roche:. Wendtner:Hofmann-La Roche: Consultancy, Honoraria, Research Funding. Hallek:Roche: Consultancy, Honoraria, Research Funding; Mundipharma: Research Funding; Celgene: Honoraria.