Current state of hematopoietic cell transplantation in CLL as smart therapies emerge

The European landscape on allogeneic haematopoeietic cell transplantation in Chronic Lymphocytic Leukaemia between 2009 and 2019: a perspective from the Chronic Malignancies Working Party of the EBMT

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.

Minimal residual disease in chronic lymphocytic leukemia: A consensus paper that presents the clinical impact of the presently available laboratory approaches

Chronic lymphocytic leukemia (CLL) is a malignancy defined by the accumulation of mature lymphocytes in the lymphoid tissues, bone marrow, and blood. Therapy for CLL is guided according to the Rai and Binet staging systems. Nevertheless, state-of-the-art protocols in disease monitoring, diagnostics, and prognostics for CLL are based on the assessment of minimal residual disease (MRD). MRD is internationally considered to be the level of disease that can be detected by sensitive techniques and represents incomplete treatment and a probability of disease relapse. MRD detection has been continuously improved by the quick development of both flow cytometry and molecular biology technology, as well as by next-generation sequencing. Considering that MRD detection is moving more and more from research to clinical practice, where it can be an independent prognostic marker, in this paper, we present the methodologies by which MRD is evaluated, from translational research to clinical practice.

Experience with ibrutinib for first-line use in patients with chronic lymphocytic leukemia

Ibrutinib is the first in-class, orally administered, Bruton's tyrosine kinase (BTK) inhibitor that abrogates the critical signaling downstream of the B-cell receptor (BCR). This signaling is required for B-cell survival, proliferation and interaction with the microenvironment. Ibrutinib proved active in preclinical models of lymphoproliferative diseases and achieved impressive response rates in heavily pretreated relapsed and refractory (R/R) patients with chronic lymphocytic leukemia (CLL). Ibrutinib prolonged survival compared to standard therapy and mitigated the effect of most poor prognostic factors in CLL, thus becoming the main therapeutic option in high-risk populations. Moreover, compared with standard chemoimmunotherapy (CIT) for adults, ibrutinib causes fewer cytopenias and infections, while having its own unique toxicity profile. Its efficacy in relapsed patients as well as its tolerability have led to its increased use in previously untreated patients, especially in those with poor prognostic markers and/or the elderly. This review elaborates on ibrutinib's unique toxicity profile and the mechanisms of acquired resistance leading to progression on ibrutinib, since both are critical for understanding the obstacles to its first-line use. We will further evaluate the data from ongoing clinical trials in this setting and explore future options for combination therapy.

Treatment of Del17p and/or aberrant TP53 chronic lymphocytic leukemia in the era of novel therapies

More effective therapies are emerging, with better toxicity profiles, and are being incorporated into modern treatment algorithms of chronic lymphocytic leukemia at various stages of the disease, including for patients harboring Del17p and/or aberrant TP53. Ibrutinib, an inhibitor of Bruton's tyrosine kinase, has demonstrated impressive response rates in the relapsed/refractory setting, including in the setting of Del17p and/or TP53 mutations. Venetoclax, an inhibitor of BCL-2 known to play an important role in regulating cell death, has been approved recently for treatment of patients with chronic lymphocytic leukemia with Del17p who have received at least one prior therapy. Unfortunately, a cure remains unattainable unless eligible patients are offered an allogeneic hematopoietic cell transplant. However, hematopoietic cell allografting is limited by the availability of suitable donors and significant morbidity and mortality. Recent clinical practice recommendations by the American Society for Blood and Marrow Transplantation have relegated the role of transplantation to later stages of the disease. In patients with evidence of Richter syndrome, frontline consolidation allogeneic hematopoietic cell transplantation remains the most desirable approach owing to the limited activity of ibrutinib or other novel therapies. Further therapeutic advances would require enrolling these patients in large clinical trials that evaluate novel therapies alone or in combination with traditional chemotherapies or even in the setting of posttransplant consolidation/maintenance.