Subcutaneous Alemtuzumab Combined with Oral Dexamethasone, Followed by Alemtuzumab Maintenance or Allo-SCT In CLL with 17p- or Refractory to Fludarabine – Interim Analysis of the CLL2O Trial of the GCLLSG and FCGCLL/MW

Abstract 920

CLL refractory to purine analogues (e.g. fludarabine, F) or with 17p- is associated with very poor prognosis. Alemtuzumab is active in F-refractory CLL, and has proven efficacy in patients (pts) with 17p-. However, outcome of F-refractory CLL is still poor in terms of remission rate and duration of remission. The multinational, multicenter CLL2O trial aims at achieving a higher remission rate by adding high-dose dexamethasone to alemtuzumab, and prolongation of remission duration and survival by alemtuzumab maintenance or allogeneic stem-cell transplantation (allo-SCT).

Pts with CLL refractory (no PR/CR or PR/CR < 6 months) to F-based (e.g. FR, FC, FCR) or similar chemotherapy (i.e. pentostatin, cladribine, bendamustine), or exhibiting 17p- (untreated or at relapse) were eligible if they had “active disease”. Treatment was with subcutaneous alemtuzumab 30 mg weekly × 3 for 28 days, combined with oral dexamethasone 40 mg on days 1–4 and 15–18, and prophylactic pegfilgrastim 6 mg days 1 and 15. Depending on the remission status, pts were treated for up to 12 weeks. If CR was documented at 4 or 8 weeks, or at least SD was achieved at 12 weeks, consolidation was scheduled with either allo-SCT or alemtuzumab maintenance with 30mg weekly every 14 days for up to 2 years (yrs). Decision for one of the two consolidation options was at discretion of patient and physician.

From January 2008 to July 2010, 80 pts were enrolled at 22 centers and 79 were eligible; F-refractory (n=31), 17p- without prior therapy (n=31), and 17p- in relapse (n=17). Median age was 65 yrs in the F-refractory (range 38–76) and 17p- 1^st-line group (36-76), and 60 yrs for the 17p- relapse group (54-73) with male predominance (F-refractory 74%, 17p- 1^st-line 71%, 17p- relapse 82%). In the 17p- 1^st-line and relapse groups, 52% and 50% were stage Binet C and exhibit reduced performance status (ECOG 1–2), compared to 81% Binet C and 60% ECOG 1–2 for the F-refractory cohort. Pretreated pts had received a median of 2 prior lines (F-refractory 1–6; 17p- relapse 1–5), and 5 pts had received prior SCT. In the F-refractory group, 16% of pts had 11q- and 52% had 17p-. IGHV was unmutated in 64% of 17p- groups and 72% in the F-refractory group. The median levels of ß2-MG / TK were 4.35 / 35.40 in the 17p- groups and 4.12 / 22.65 in the F-refractory group.

Treatment data are currently available for 50 pts who completed induction therapy; F-refractory (n=19),17p- 1^st-line (n=22), 17p- relapse (n=9). Full treatment duration (12 weeks) could be achieved in 47% F-refractory, 67% 17p- relapsed and 82% 17p- 1^st-line pts. In the latter cohort, early stop of therapy was mainly correlated with CR, while in the F-refractory cohort with disease progression (n=2) and infections (n=5, 4 with no documented response). Response rates (ORR / CR) were 47% / 0% in the F-refractory cohort, 78% / 0% in the 17p- relapsed, and 100% / 23% in the 17p- 1^st-line cohorts (as compared to this, ORR / CR was 71.4% / 4.8% with FCR in the 17p- 1^st-line group of CLL8).

Adverse events during treatment were mostly grade 1/2 apart from hematotoxicity. Grade 3/4 non-CMV infection occurred in 35% of F-refractory, 12% of 17p- relapsed, and 16% of 17p- 1^st-line pts. CMV reactivation was observed in 32 % of the 17p- 1^st-line pts, and less for the pretreated groups (F-refractory 16%, 17p- relapsed 18%). All CMV episodes were successfully treated, and there was no CMV-related death. Among 18 pts documented to receive alemtuzumab maintenance treatment, so far 3 SAEs have been reported: ITP (n=1, twice in the same pt), and fever / diarrhea / thyroiditis (n=1).

At a median follow-up of 41.9 weeks (maintenance 54.7 weeks, allo-SCT 29 weeks), there were 7 (37%) deaths in the in the F-refractory cohort, 2 due to disease progression, and 5 due to infection. For the 17p- relapsed group, 3 progressions and 3 deaths were reported, with one case in each treatment option (SCT/maintenance), and one pt in salvage therapy. In the 17p- 1^st-line cohort, 4 progressions occurred, 2 pts died, both in maintenance therapy. At 12 months, estimated overall survival was 54%, 66% and 100% in the F-refractory, 17p- relapse, and 17p- 1^st-line cohorts, respectively. Accrual is currently ongoing with a target enrolment of 122 pts and updated results will be presented at the meeting.