Impact of Low-Burden TP53 Mutations in the Management of CLL

Realizing precision medicine in chronic lymphocytic leukemia: Remaining challenges and potential opportunities

Patients with chronic lymphocytic leukemia (CLL) exhibit diverse clinical outcomes. An expanding array of genetic tests is now employed to facilitate the identification of patients with high-risk disease and inform treatment decisions. These tests encompass molecular cytogenetic analysis, focusing on recurrent chromosomal alterations, particularly del(17p). Additionally, sequencing is utilized to identify TP53 mutations and to determine the somatic hypermutation status of the immunoglobulin heavy variable gene. Concurrently, a swift advancement of targeted treatment has led to the implementation of novel strategies for patients with CLL, including kinase and BCL2 inhibitors. This review explores both current and emerging diagnostic tests aimed at identifying high-risk patients who should benefit from targeted therapies. We outline existing treatment paradigms, emphasizing the importance of matching the right treatment to the right patient beyond genetic stratification, considering the crucial balance between safety and efficacy. We also take into consideration the practical and logistical issues when choosing a management strategy for each individual patient. Furthermore, we delve into the mechanisms underlying therapy resistance and stress the relevance of monitoring measurable residual disease to guide treatment decisions. Finally, we underscore the necessity of aggregating real-world data, adopting a global perspective, and ensuring patient engagement. Taken together, we argue that precision medicine is not the mere application of precision diagnostics and accessibility of precision therapies in CLL but encompasses various aspects of the patient journey (e.g., lifestyle exposures and comorbidities) and their preferences toward achieving true personalized medicine for patients with CLL.

Low-burden TP53 mutations represent frequent genetic events in CLL with an increased risk for treatment initiation

TP53 aberrations predict chemoresistance and represent a contraindication for the use of standard chemoimmunotherapy in chronic lymphocytic leukaemia (CLL). Recent next-generation sequencing (NGS)-based studies have identified frequent low-burden TP53 mutations with variant allele frequencies below 10%, but the clinical impact of these low-burden TP53 mutations is still a matter of debate. In this study, we aimed to scrutinise the subclonal architecture and clinical impact of TP53 mutations using a sensitive, NGS-based mutation analysis in a 'real-world' cohort of 901 patients with CLL. In total, 225 TP53 mutations were identified in 17.5% (158/901) of the patients; 48% of these alterations represented high-burden mutations, while 52% were low-burden TP53 mutations. Low-burden mutations as sole alterations were identified in 39% (62/158) of all mutated cases with 82% (51/62) of these being represented by a single low-burden TP53 mutation. Patients harbouring low-burden TP53 mutations had significantly lower time to first treatment compared to patients with wild-type TP53. Our study has expanded the knowledge on the frequency, clonal architecture, and clinical impact of low-burden TP53 mutations. By demonstrating that patients with sole low-burden TP53 variants represent more than one-third of patients with TP53 mutations and have an increased risk for treatment initiation, our findings strengthen the need to redefine the threshold of TP53 variant reporting to below 10% in the routine diagnostic setting.