Open-Label Early-Access Programs (EAPs) for Ibrutinib in Patients with Relapsed/ Refractory Chronic Lymphocytic Leukemia (CLL) or Mantle-Cell Lymphoma (MCL)

Background:Treatment options for patients with relapsed/refractory chronic lymphocytic leukemia (CLL) or mantle cell lymphoma (MCL) are limited. Ibrutinib is a first-in-class small-molecule inhibitor of Bruton's tyrosine kinase. These extended access programs (EAP) provided patient access to ibrutinib in Brazil and real-world safety data was collected, at a time when the medication was not commercially available in Brazil.

Methods:These two prospective, multicenter, open-label EAPs of single-agent ibrutinib were conducted between April 2013 and August 2017, and enrolled Brazilian patients with relapsed/refractory CLL or MCL. Eligible patients must have progressive disease after at least one prior therapy and not suitable for retreatment with purine analogue therapy. After a 30-day screening, eligible patients received once-daily oral ibrutinib 420 mg (CLL) or 560 mg (MCL) continuously until disease progression, unacceptable toxicity, absence of clinical benefit, or end of EAP, whichever occurred first. Doses could be withheld or reduced based on toxicity. Patients were monitored for safety and disease evaluations were conducted per routine local standard of care practices.

Results:Of 33 CLL patients enrolled, 32 received one dose of drug or more and were included in the safety analysis. Median age was 62.5 years, and most patients were male (n=24; 75%) and white (n=27; 84.4%). The median time from CLL diagnosis to study inclusion was 83.8 months and from diagnosis to relapsed/refractory state, 42.0 months. The median number of ibrutinib cycles was 12.0 (1.0-16.0) with a median treatment duration of 11.1 (0.9-11.6) months. Eight patients discontinued due to adverse event (AE; n = 4; 12.5%), consent withdrawal (n = 2; 6.3%), death (n = 1; 3.1%), or disease progression (n = 1; 3.1%). AEs leading to treatment discontinuation were intestinal bleeding, neutropenia, infection, and gastric tumor (one patient each). Three (9.4%) patients had dose reductions: one (3.1%) for neutropenia, febrile neutropenia with pneumonia, or worsening fatigue. 21 patients (65.6%) had at least one Grade ≥3 (G3) AE or serious AE (SAE). The most frequent G3 or SAEs included neutropenia in 8 (25.0%), fatigue (1), leukocytosis (1), and pneumonia (3). No atrial fibrillation or bleeding AEs were reported. Among the 47 G3 or SAEs, 17 (36.2%) were serious, 38 (80.9%) were suspected to be related to ibrutinib, and 39 (83.0%) were resolved without sequelae.

All 13 MCL patients enrolled in the study were included in the safety analysis. The median age was 60.0 years, and most patients were male (n=9; 69.2%) and white (n=9; 69.2%). The median number of prior treatment regimens were 3. The median time from diagnosis to the first dose of ibrutinib was 20.4 months. The median number of ibrutinib cycles was 19 (4.0-34.0) with a median treatment duration of 16.8 (3.6-30.5) months. Eight patients discontinued because of either death (n=3; 23.1%) or disease progression (n=5; 38.5%). The three patients died with treatment-emergent G4 or higher AEs, including pneumonia (G5; probably treatment-related [TR]), sepsis (G5; not TR), and dyspnea (G4; doubtful TR); 8 patients (61.5%) had at least one G3 or higher treatment-emergent AE. The most frequent AE was diarrhea (n=3; 23.1%), and other AEs were reported in one patient each (i.e. abdominal hernia, anemia, appendicitis, dyspnea, febrile neutropenia, influenza, leukocytosis, neutropenia, pneumonia, productive cough, renal failure/insufficiency, retroperitoneal abscess, thrombocytopenia). Three (23.1%) patients had ibrutinib dose modifications: one (7.7%) each because of appendicitis/tuberculosis, thrombocytopenia, and diarrhea/retroperitoneal abscess/dyspnea. No atrial fibrillation or bleeding AEs were reported. Among the 20 G3 or higher treatment-emergent AEs, 14 (70%) were suspected to be related to ibrutinib and 15 (75%) were resolved.

Conclusions: This is the first real-world experience with ibrutinib monotherapy for CLL and MCL in Brazil. Overall, treatment was well tolerated with no unexpected toxicities. No atrial fibrillation or bleeding AEs were reported. Of 32 patients with relapsed/refractory CLL, 24 (80%) remained on therapy, 4 (12.5%) discontinued due to AEs, 1 (3.1%) each died or experienced disease progression. Among 13 patients with relapsed/refractory MCL, 5 (38.5%) remained on the therapy, 3 (23.1%) died and 5 (38.5%) experienced disease progression.