Summary Background Patients with chronic lymphocytic leukaemia (CLL) with TP53 aberrations respond poorly to first-line chemoimmunotherapy resulting in early relapse and short survival. We investigated the safety and activity of ibrutinib in previously untreated and relapsed or refractory CLL with TP53 aberrations. Methods In this investigator-initiated, single-arm phase 2 study we enrolled eligible adult patients with active CLL with TP53 aberrations at the National Institutes of Health Clinical Center (Bethesda, MD, USA). Patients received 28-day cycles of ibrutinib 420 mg orally once daily until disease progression or the occurrence of limiting toxicities. The primary endpoint was overall response to treatment at 24 weeks in all evaluable patients. This study is registered with ClinicalTrials.gov number NCT01500733, and is fully enrolled. Findings Between Dec 22, 2011 and Jan 2, 2014 we enrolled 51 patients; 47 had CLL with deletion 17p13.1 and four carried a TP53 mutation in the absence of deletion 17p13.1. All patients had active disease requiring therapy. 35 enrolled patients had previously untreated CLL and 16 had relapsed or refractory disease. Median follow-up was 24 months (IQR 12·9-27·0). 33 previously untreated patients and 15 patients with relapsed or refractory CLL were evaluable for response at 24 weeks. 32 (97%; 95% CI 86-100) of 33 previously untreated patients achieved an objective response, including partial response in 18 patients (55%) and partial response with lymphocytosis in 14 (42%). One patient had progressive disease at 0·4 months. 12 (80%; 95% CI 52-96) of the 15 patients with relapsed or refractory CLL had an objective response: six (40%) achieved a partial response and six (40%) a partial response with lymphocytosis; the remaining three (20%) patients had stable disease. Grade 3 or worse treatment-related adverse events were neutropenia in 12 (24%) patients (grade 4 in one [2%] patient), anaemia in seven (14%) patients, and thrombocytopenia in five (10%) patients (grade 4 in one [2%] patient). Grade 3 pneumonia occurred in three (6%) patients, and grade 3 rash in one (2%) patient. Interpretation The activity and safety profile of single-agent ibrutinib in CLL with TP53 aberrations is encouraging and supports its consideration as a novel treatment option for patients with this high-risk disease in both first-line and second-line settings Funding Intramural Research Program of the National Heart, Lung, and Blood Institute and the National Cancer Institute, Danish Cancer Society, Novo Nordisk Foundation, National Institutes of Health Medical Research Scholars Program, and Pharmacyclics Inc.

Approaches to the measurement of lymphohematopoietic chimerism have evolved from laboratory research to important clinical tools. However, there has been no logical, consistent, and uniform set of recommendations for the measurement of chimerism in clinical transplantation. The National Marrow Donor Program and the International Bone Marrow Transplant Registry (IBMTR) sponsored a workshop to discuss the use of chimerism analysis after allogeneic transplantation. The workshop was organized in an effort to make reasonable recommendations regarding laboratory techniques, the types of specimens to be studied, and the frequency of analysis. The panel recommended the following guidelines: 1. Chimerism analysis should use sensitive, informative techniques. At present, short tandem repeats (STR) or variable number tandem repeats (VNTR) analysis is the approach most likely to give reproducible informative data. 2. Peripheral blood cells are generally more useful than bone marrow cells for chimerism analysis. 3. Lineage-specific chimerism should be considered the assay of choice in the setting of nonmyeloablative and reduced-intensity conditioning. 4. The use of T-cell depletion, nonmyeloablative or reduced-intensity conditioning, or novel graft-versus-host disease (GVHD) prophylactic regimens warrants chimerism analysis at 1, 3, 6, and 12 months, because interventions such as donor lymphocyte infusions may depend on chimerism status. 5. In nonmyeloablative transplantation, the early patterns of chimerism may predict either GVHD or graft loss. Therefore, more frequent (every 2-4 weeks) peripheral blood analysis may be warranted. 6. For nonmalignant disorders, chimerism generally should be measured 1, 2, and 3 months after transplantation. Interventions to enhance donor engraftment must be considered on a disease-specific basis in relation to concurrent GVHD and, ultimately, clinical rationale.

Nonmyeloablative conditioning followed by a T-cell-depleted hematopoietic stem-cell allograft is a feasible option for patients with chronic granulomatous disease, recurrent life-threatening infections, and an HLA-identical family donor.

The safety and efficacy of ibrutinib (420 mg) in chronic lymphocytic leukemia (CLL) were evaluated in a phase 2 study; 51 patients had aberration (TP53 cohort) and 35 were enrolled because of age 65 years or older (elderly cohort). Both cohorts included patients with treatment-naive (TN) and relapsed/refractory (RR) CLL. With the median follow-up of 4.8 years, 49 (57.0%) of 86 patients remain on study. Treatment was discontinued for progressive disease in 20 (23.3%) patients and for adverse events in 5 (5.8%). Atrial fibrillation occurred in 18 (20.9%) patients for a rate of 6.4 per 100 patient-years. No serious bleeding occurred. The overall response rate at 6 months, the primary study endpoint, was 95.8% for the TP53 cohort (95% confidence interval, 85.7%-99.5%) and 93.9% for the elderly cohort (95% confidence interval, 79.8%-99.3%). Depth of response improved with time: at best response, 14 (29.2%) of 48 patients in the TP53 cohort and 9 (27.3%) of 33 in the elderly cohort achieved a complete response. Median minimal residual disease (MRD) in peripheral blood was 3.8 × 10 at 4 years, with MRD-negative (<10) remissions in 5 (10.2%) patients. In the TP53 cohort, the estimated 5-year progression-free survival (PFS) was 74.4% in TN-CLL compared with 19.4% in RR-CLL ( = .0002), and overall survival (OS) was 85.3% vs 53.7%, respectively ( = .023). In the elderly cohort, the estimated 5-year PFS and OS in RR-CLL were 64.8% and 71.6%, respectively, and no event occurred in TN-CLL. Long-term administration of ibrutinib was well tolerated and provided durable disease control for most patients. This trial was registered at www.clinicaltrials.gov as #NCT01500733.