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Management of Richter transformation (RT) is particularly challenging, with survival estimates <1 year. We report on outcomes of 66 RT patients undergoing allogeneic-HCT (allo-HCT) between 2008 and 2018 registered with the EBMT. Median age at allo-HCT was 56.2 years (interquartile range (IQR), 51.3-63.1). Median time from RT to allo-HCT was 6.9 months (IQR, 4.9-11) and 28 (42.4%) were in complete remission (CR). The majority underwent reduced intensity conditioning (66.2%) using peripheral blood derived stem cells. Eighteen (27.3%) patients had a matched sibling donor, 24 (36.4%) a matched unrelated donor and the remaining were mismatched. Median follow-up was 6.6 years; 1- and 3- year overall and progression free survival (PFS) (95% CI) was 65% (54-77) and 39% (27-51) and 53% (41-65) and 29% (18-40), respectively. Patients in CR at time of allo-HCT had significantly better 3-year PFS (39% vs. 21%, p = 0.032). Cumulative incidences of grade II-IV acute graft versus host disease (GVHD) at day +100 was 41% (95% CI 29-53) and chronic GVHD at 3 years was 53% (95% CI 41-65). High rates of non-relapse mortality (NRM) were observed; 38% (95% CI, 26-50) at 3 years. Although potentially curative, approaches to reduce considerable NRM and chronic GVHD rates are required., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Allogeneic transplantation (allo-HCT) is a curative treatment in CLL whose efficacy including the most severe forms had led to the 2006 EBMT recommendations. The advent after 2014 of targeted therapies has revolutionized CLL management, allowing prolonged control to patients who have failed immunochemotherapy and/or have TP53 alterations. We analysed the pre COVID pandemic 2009-2019 EBMT registry. The yearly number of allo-HCT raised to 458 in 2011 yet dropped from 2013 onwards to an apparent plateau above 100. Within the 10 countries who were under the EMA for drug approval and performed 83.5% of those procedures, large initial differences were found but the annual number converged to 2-3 per 10 million inhabitants during the 3 most recent years suggesting that allo-HCT remains applied in selected patients. Long-term follow-up on targeted therapies shows that most patients relapse, some early, with risk factors and resistance mechanisms being described. The treatment of patients exposed to both BCL2 and BTK inhibitors and especially those with double refractory disease will become a challenge in which allo-HCT remains a solid option in competition with emerging therapies that have yet to demonstrate their long-term effectiveness., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

No studies have been reported so far on bridging treatment with idelalisib for patients with chronic lymphocytic leukemia (CLL) prior to allogeneic hematopoietic cell transplantation (alloHCT). To study potential carry-over effects of idelalisib and to assess the impact of pathway-inhibitor (PI) failure we performed a retrospective EBMT registry-based study. Patients with CLL who had a history of idelalisib treatment and received a first alloHCT between 2015 and 2017 were eligible. Data on 72 patients (median age 58 years) were analyzed. Forty percent of patients had TP53 mut/del CLL and 64% had failed on at least one PI. No primary graft failure occurred. Cumulative incidences of acute GVHD °II-IV and chronic GVHD were 51% and 39%, respectively. Estimates for 2-year overall survival (OS), progression-free survival (PFS), and cumulative incidences of relapse/progression (CIR) and non-relapse mortality NRM were 59%, 44%, 25%, and 31%. In univariate analysis, drug sensitivity was a strong risk factor. For patients who had failed neither PI treatment nor chemoimmunotherapy (CIT) the corresponding 2-year estimates were 73%, 65%, 15%, and 20%, respectively. In conclusion, idelalisib may be considered as an option for bridging therapy prior to alloHCT. Owing to the high risk for acute GVHD intensified clinical monitoring is warranted.

The purpose of our study is to provide information on safety and efficacy of ibrutinib as salvage treatment after allo-HSCT for CLL. A total of 56 patients were included, 36 (64%) males; median age at transplantation was 48 years (range: 35-64) and the median number of treatment lines prior to transplantation was 3 (1-10). The median time between allo-HSCT and Ibrutinib was 30 months (range: 1-140). Overall, 40 (71%) patients responded to Ibrutinib; 23 (41%) PR, and 17 (30%) CR. At time of ibrutinib initiation, ten patients had active chronic GVHD that resolved under Ibrutinib, whilst a single patient developed limited de novo chronic GVHD on Ibrutinib. Fourteen patients discontinued ibrutinib, four because of toxicity and ten because of disease progression. Overall, 14 patients progressed (median PFS = 24 months) among them 10 died. Two-year OS and PFS probabilities were 72% (95% CI: 52-84) and 50% (95% CI: 32-66), respectively. Patients with late relapse after allo-HSCT (≥24 months) had a better PFS after ibrutinib. Our study shows that ibrutinib can be safely administered for CLL relapse after allo-HSCT, with comparable efficacy to non-transplanted patients with high-risk disease.

The aim of this retrospective study was to investigate the safety and efficacy of allogeneic hematopoietic cell transplantation (alloHCT) in patients pre-treated with ibrutinib. Eligible were patients aged >18 years allotransplanted for chronic lymphocytic leukemia (CLL) or mantle cell lymphoma (MCL) after prior exposure to ibrutinib who were registered with the EBMT registry. Seventy patients (CLL 48, MCL 22) were included. At the time of alloHCT, 73% of the patients were ibrutinib responsive. All patients except one engrafted, and acute GVHD grade 2-4 (3-4) was observed in 49% (12%) of 68 evaluable patients. The cumulative incidence of chronic GVHD was 54% 1 year after transplant. In the CLL group, 12-month non-relapse mortality, relapse incidence (RI), progression-free survival (PFS), and overall survival (OS) were 10, 30, 60, and 72%, respectively, and in the MCL group 5, 19, 76, and 86%, respectively. Pre-transplant ibrutinib failure and poor performance status predicted inferior RI, PFS and OS in the CLL group. In conclusion, ibrutinib does not affect the safety of a subsequent alloHCT. While the relatively high post-transplant relapse risk in ibrutinib-exposed patients with CLL deserves further study, in patients with MCL consolidating disease responses to ibrutinib with alloHCT seems to be a promising option.

Allogeneic hematopoietic stem cell transplantation (HCT) may result in long-term disease control in high-risk chronic lymphocytic leukemia (CLL). Recently, haploidentical HCT is gaining interest because of better outcomes with post-transplantation cyclophosphamide (PTCY). We analyzed patients with CLL who received an allogeneic HCT with a haploidentical donor and whose data were available in the EBMT registry. In total 117 patients (74% males) were included; 38% received PTCY as GVHD prophylaxis. For the whole study cohort OS at 2 and 5 yrs was 48 and 38%, respectively. PFS at 2 and 5 yrs was 38 and 31%, respectively. Cumulative incidence (CI) of NRM in the whole group at 2 and 5 years were 40 and 44%, respectively. CI of relapse at 2 and 5 yrs were 22 and 26%, respectively. All outcomes were not statistically different in patients who received PTCY compared to other types of GVHD prophylaxis. In conclusion, results of haploidentical HCT in CLL seem almost identical to those with HLA-matched donors. Thereby, haploidentical HCT is an appropriate alternative in high risk CLL patients with a transplant indication but no available HLA-matched donor. Despite the use of PTCY, the CI of relapse seems not higher than observed after HLA-matched HCT.