Clinical Outcome of B-Cell Chronic Lymphocytic Leukemia Following Alemtuzumab Therapy: Retrospective Study within Various Cytogenetic Risk Categories
Authors: Fiegl Michael , Erdel Martin , Tinhofer Inge , Hopfinger Georg , Eigenberger Karin , Falkner Florian , Falkner Andreas , Brychtova Yvona , Panovska Anna , Doubek Michael , Zabernigg August , Sodia Sigrun , Mühlberger Helmut , Fonatsch Christa , Gastl Günther , Mayer Jiri , Greil Richard 
Published: April 2020

B-cell chronic lymphocytic leukemia (CLL) with 17p deletion responds poorly to chemotherapeutic agents. This retrospective study evaluated the benefit of alemtuzumab monotherapy in unselected patients with advanced CLL, categorized by cytogenetic profile.

Methods: This is the largest data base with efficacy analysis of alemtuzumab in CLL stratified according to cytogenetics. Detailed data analysis was done in 138 CLL patients, in whom cytogenetic analysis was performed by FISH using the standard CLL analysis categorized according to Doehner et al. (N Engl J Med343, 1910; 2000). Responses were evaluated according to the NCI criteria; progression-free survival (PFS) and overall survival (OS) were also assessed.

Results: 73% of the patients were male. At start of alemtuzumab therapy, the median age was 64 years (range, 46–92); 12% were in Rai stage I, 18% in stage II, 20% in stage III, and 50% in stage IV. The median number of two prior therapies was 2 (range, 0–10); of the patients who received prior fludarabine (F) (n=113), 70% were F-refratory, 25% sensitive, and in 5% this was unknown. 30% and 17% of patients had bulky lymphadenopathy (&gt;5 cm) and giant splenomegaly (&gt;20 cm), respectively. Cytogenetic abnormalities were as follows: 13q deletion 14%; trisomy 12, 12%, 11q deletion 20%; 17p deletion, 33%, none of these, 22%. The overall response rate (ORR) was 38% in the total cohort. ORR was 53%, 56%, 21%, and 44% in the subgroup of 13q deletion, trisomy 12, 11q deletion, and 17p deletion, respectively; patients without any of these abnormalities had an ORR of 27%. From start of alemtuzumab, median PFS and OS for the whole cohort was 6.9 months and 30 months, respectively. Notably, PFS and OS in 17p deletion patients was 7.1 months and 19.1 months, respectively, an encouraging outcome when considering the unfavourable risk profile in these patients. In 17p deletion patients, response was remarkable also in disease involved lymph nodes (78%). Patients with F-resistant disease and 17p deletion, an extraordinarily poor prognostic group (n=25), had encouraging ORR, PFS, and OS rates (28%; 7.2 months; and 19.1 months, respectively), which did not differ from those in F-resistant patients with good risk cytogenetics. In a multivariate Cox regression analysis, independent risk factors for shorter OS were anemia (hazard ratio [HR] = 2.48; 95% CI, 1.50–4.11; P &lt;.001), ≥3 of prior lines of therapy (HR = 2.00; 95% CI, 1.24–3.24, P =.005), and poor risk cytogenetics ([17p deletion and 11q deletion], HR = 2.23; 95% CI 1.35–3.69, P =.002).

Conclusion: Alemtuzumab was effective in CLL across all cytogenetic categories evaluated. In patients with favorable cytogenetics, we observed that alemtuzumab is a highly effective therapy even when conventional chemotherapy has failed. Patients with 17p deletion achieved quite favorable ORR and OS upon alemtuzumab. Thus, the 17p deletion group can often be shifted to an “intermediate” risk CLL, and responding patients are frequently re-treated with alemtuzumab.