Multicenter Retrospective Observational Study to Assess the Clinical Characteristics and the Outcome of Patients with Relapsed or Refractory Mantle Cell Non-Hodgkin's Lymphoma Treated in Italy According to the Ibrutinib Named Patient Program

Mantle cell lymphoma (MCL) is a rare and aggressive subtype of non-Hodgkin Lymphoma. Although a typical presentation as an indolent lymphoma, without systemic symptoms and with a good performance status, the mantle cell lymphoma is an aggressive one, hardly curable with standard chemo-immunotherapy. Although current approaches to mantle cell lymphoma, including newer agents (such as bortezomib, lenalidomide, temsirolimus and ibrutinib) and autologous stem cell transplantation, have greatly improved the outcomes of affected patients, this disease is still characterized by high relapse rates, with most patients eventually dying of lymphoma progression. Before official approval by EMA, patients with relapsed/refractory mantle cell lymphoma with unsatisfied critical medical urgency were granted ibrutinib early access through a Named Patient Program in Italy (NPP, DM 8 May 2003). This observational, non-interventional, retrospective, multicenter study focuses on collecting information about the effectiveness and safety of ibrutinib as single-agent in patients who received at least one dose of ibrutinib under the NPP in the period between 29/Jul/2014 and 25/Jan/2015 in Italy. Data from patients treated with ibrutinib outside a controlled clinical trial within a NPP could give additional information about the clinical use, treatment duration, efficacy and toxicity of ibrutinib given to relapsed or refractory MCL patients in a real life context.

Fifty-three heavily pretreated patients were enrolled. They had received a median of previous therapies of 3, comprising lenalidomide, bortezomib, temsirolimus and autologous stem transplant. Ninety-one percent had measurable disease and 83.0% had and ECOG performance status ≤2. At the end of therapy there were 11 complete responses (20.8%), 7 partial responses, 5 stable diseases and 30 progressions with an overall response rate of 33.9%. Twenty-six patients received ≥3 concomitant medications during ibrutinib therapy. At 20 months overall survival (OS) was 26.8% (median reached at 9 months) and disease free survival (DFS) 75% at 15 months: 10/11 patients are in continuous complete response with a median of 10.5 months. Hematological toxicities were manageable, 6 thrombocytopenia occurred, of which only 2 grade 4 (due to disease bone marrow infiltration) and the other 4 related to ibrutinib. Main extra-hematological toxicities were diarrhea (9.4%) and lung infections (7.5%) which all lead to early drug discontinuation. The observed occurrence of diarrhea by severity was 0 for CTCAE Grade 1, 4 for Grade 2, 2 for Grade 3 and 0 for Grade 4. Lung infection had a lower occurrence: 0, 2, 2 and 0 split by CTCAE Grade 1, 2, 3 and 4 respectively. There is a boundary zone in the passage from phase III to phase IV trials, i.e. from experimental to marketing and free use phases: in this zone we can find NPP and compassionate and off-label use. Despite the known potential bias of all the observational retrospective studies, reports on the real life experience make an important contribution to medical knowledge prior to widespread utilization: ibrutinib therapy is effective and tolerable also in a clinical setting mimicking the real world. Our results, in fact, are superimposable to those obtained in clinical trials: for safety, thrombocytopenia, diarrhea and lung infections are the relevant adverse events to be clinically focused on; for effectiveness, ibrutinib is confirmed to be a valid option for refractory/relapsed MCL.