Outcome of Patients with Relapsed/Refractory (R/R) Chronic Lymphocytic Leukemia (CLL) and/or 17p Deletion/TP53 Mutations Treated with Ibrutinib According to a Named Patient Program (NPP) in Italy: Preliminary Analysis of a Real Life Retrospective Study

Introduction. Observational studies from patients treated outside controlled clinical trials offer real life information and are relevant to understand whether data derived from prospective trials are reproducible in the clinical practice. A retrospective observational study was carried out by the GIMEMA (Gruppo Italiano Malattie EMatologiche dell'Adulto) group in order to evaluate the clinical characteristics and outcome of patients with chronic lymphocytic leukemia (CLL) treated with ibrutinib in Italy within a Named Patient Program (NPP). The NPP was intended to offer free and early drug access to CLL patients until ibrutinib became available on the Italian market.

Methods. Patients included in the NPP program had refractory or relapsed (R/R) disease with progression within 24 months after prior chemo-immunotherapy, and/or 17p deletion/TP53 mutations. Patients were also required to have an ECOG performance status ≤2; serum creatinine ≤2 times, liver enzymes ≤3 times and total bilirubin ≤1.5 times the upper limit of normal. Key exclusion criteria were: the need of a concomitant treatment with a strong CYP3A inhibitor or warfarin, an allogeneic stem cell transplantation within the past 6 months or an ongoing active infection. All patients included in the program received ibrutinib orally as a single agent at the standard dose of 420 mg daily. Clinical data of 110 patients included in the NPP program between January 2014 and November 2014 have so far been collected and analyzed using the Research Electronic Data Capture (REDCap) system. Patients were managed at 20 Italian centers and received at least one dose of ibrutinib. Clinical data were reported by the treating physicians.

Results. The median age of patients was 69.9 years (range 49.8-83.3); 53% were in Rai stage III-IV, 32% in stage II and 15% in stage 0-I. Sixty-two percent of patients had relapsed disease, 38% were refractory to prior treatment. The presence of a 17p deletion and/or TP53 mutations was recorded in 51 R/R patients. Eighty-six percent of patients had an unmutated IGHV gene profile. The median number of prior treatments was 3 and included allogeneic stem cell transplantation in 4 cases. Two or more comorbidities were reported in 57 patients (52%) and included atrial fibrillation (AF) in 10 (9.1%) and hypertension in 40 (36.4%). After a median follow-up of 12.1 months (range, 1.6-24.6), 87 patients (79%) were still on ibrutinib. A response to ibrutinib was reported in 98/110 patients (89.1%). The best recorded response was a CR/CRi in 19 patients (17.3%), while a PR was reported in 79 patients (72%; PR-L 21.1%). Similar response rates were observed in patients with unmutated IGHV genes (91.9%) and in those with 17p deletion/TP53 mutations (90.3%). At 12 months, the progression-free survival (PFS) and overall survival (OS) were 92.9% (95%CI: 87.9-98.2) and 95.2% (95%CI: 91.1-99.4), respectively. PFS at 12 months of patients who achieved a response was 96.3%, 98.9% in unmutated IGHV patients, 90.7% in those with 17p deletion/TP53 mutations. Five patients (4.5%) died during the NPP program (1 patient each for sepsis, heart failure, ileus perforation, cancer, unknown cause). Adverse events (AE) were recorded in 75 patients (68.2%); in 47 (42.7%) they were grade ≥3. Any grade AEs recorded in ≥5% of patients were: infections (35%; grade ≥3, 22%), granulocytopenia (18.8%; grade ≥3, 17.2%), bleeding (15.5%; grade ≥3, 2.7%), fever of unknown origin or febrile neutropenia (12%; grade ≥3, 5.4%), AF (10.9%; grade ≥3, 4.5%), diarrhoea (8.3; grade ≥3, 2%), hypertension (7.2%; grade ≥3, 5.4%). A new event of AF occurred in 1/10 patients with a prior history of AF. Warfarin was required in 1 patient with AF and this was the reason for ibrutinib discontinuation.

Conclusions. The results of the first interim analysis of this retrospective, real life study confirms that ibrutinib, as a single agent, is an effective treatment for patients with poor-prognosis CLL. Our data also suggest that ibrutinib given to unselected patients, in a compassionate-use program, shows a clinical activity and a safety profile comparable to those reported in prospective trials. Data collection is ongoing in order to complete the analysis of this large NPP cohort in Italy.