Efficacy and Safety of a First Line Combined Therapeutic Approach for Young CLL Patients with Advanced or Progressive Disease Stratified According to the Biologic Features: First Analysis of the GIMEMA Multicenter Study LLC0405

Abstract 2471

Eighty-one previously untreated CLL patients, ≤60 years, with advanced/progressive disease were included in the GIMEMA LLC0405 prospective multicenter study. Patients were stratified according to the biologic features. High risk (HR) patients were defined by the presence of: 1) 17p- (≥20% of analyzed cells), or 2) 11q- with ≥1 additional unfavorable factor (IGHV germline; Zap-70+ ≥10%; CD38+ ≥7%), or 3) germline IGHV or mutated VH3-21 and ≥2 unfavorable factors (Zap-70; CD38; 6q-; trisomy 12). Low risk (LR) patients were defined by the absence of the above features. HR patients received 4 monthly courses of fludarabine and campath-1H (FluCam; Flu 30 mg/m² iv; Cam 30 mg iv, days 1–3). Responding patients underwent post-induction therapy: reduced intensity PBSC allogeneic transplant or, in the absence of a sibling donor, an autologous PBSC transplant or, in the absence of a sufficient harvest, Cam sc, 30 mg weekly for a maximum of 12 weeks. For LR patients, treatment included 6 monthly courses of fludarabine and cyclophosphamide (FC; fludarabine 30 mg/m² iv and cyclophosphamide 250 mg/m², days 1–3). All patients received bactrim prophylaxis. FluCam-treated patients underwent weekly CMV antigenemia monitoring and valacyclovir prophylaxis (2g/8h). In the presence of severe granulocytopenia, G-CSF was recommended and darbepoietin given in case of anemia (Hb <11g/dl). MRD was monitored in peripheral blood (PB) and marrow by four color-flow cytometry. The median age of patients was 55 years (range: 30–60), Rai stages III-IV were recorded in 23% of cases, 35% of patients showed “bulky” nodes (Ø&osol; ≥5 cm), 35% had 100 × 10⁹/L or more PB lymphocytes and 51% increased β2 M values. A HR profile was found in 43 patients (53%) and a LR profile in 38 (47%). Within HR patients, 93% were IGHV unmutated, 69% CD38+, 80% Zap-70+, 40% 11q- and 21% 17p-. LR patients showed one or more unfavorable biologic factors in less than a third of cases (IgVH unmutated 21%, CD38+ 17%, Zap-70+ 29%); 13q- was recorded in 42% of cases, no detectable abnormalities in 39%, trisomy 12+ in 11% and 6q- in 8%. On an intention-to treat basis, a response was observed in 79% of HR cases (CR 26%, MRD- 19%) and in 87% of LR cases (CR 55%, MRD- 18%). In univariate analysis, age, IgG levels, β2 M, IgVH status, CD38 and Zap-70 played a significant role on CR achievement in HR patients, while CD38 was the only significant parameter for LR patients. As post-remission therapy, 2 HR patients received Cam, while 11 underwent a transplant procedure (allogeneic: 4, autologous: 7). The PFS probability at 36 months was 44% (95% CI: 36.9–51.8) for HR patients and 64% (95%CI: 53.6–76.7) for LR patients. In univariate analysis, β2 M and Zap-70 showed a significant effect on the PFS of HR patients, while a higher PB lymphocyte count (≥60×10⁹/L) was associated with a lower PFS (p=0.07) in LR patients. The CR rate and PFS at 36 months after FluCam were 18% and 18% for 11q- patients, and 11% and 49% for 17p- patients. The OS probability at 36 months was 81% (95% CI: 71–93.3) for HR patients and 89% (95%CI:80.2–98.6) for LR patients. Cytogenetic abnormalities played a significant role (p=.02) on OS probability of HR patients. In particular, 17p- was associated with a lower survival probability (p=.04), while the OS of LR patients was influenced by the lymphocyte count (p=0.05). All transplanted patients are alive with a median follow-up of 31 months (range:16–42). Granulocytopenia was observed in 21% of cases treated with FluCam and in 32% of those treated with FC. Grade III-IV infections were recorded in 7% of FluCam-treated patients and in 13% of FC- treated patients. Asymptomatic CMV reactivation was detected in 3 FluCam-treated cases (7%). No FluCam-related deaths were observed, while 4 FC-related deaths were recorded (febrile granulocytopenia, 2 cases; cerebral hemorrhage, 1; cerebral abscesses of unknown origin, 1). In conclusion, an unfavorable biologic profile was observed in about half young CLL patients requiring first line treatment. Front-line FluCam was well tolerated and effective for most young CLL patients with an unfavorable biologic profile. However, our results suggest that FluCam is not the optimal treatment approach for 11q- patients. Front-line FC was associated with a high CR rate and prolonged PFS and OS probabilities in patients with a favorable biologic profile. Nevertheless, in young CLL patients FC-related severe granulocytopenia was a frequent reason of treatment failure.