Novel Agents in Chronic Lymphocytic Leukemia: New Combination Therapies and Strategies to Overcome Resistance

Simple Summary Nowadays, many patients with chronic lymphocytic leukemia (CLL) are treated with so-called novel agents, including BTK inhibitors, Bcl-2 inhibitors and PI3K inhibitors. As CLL is a chronic disease, most patients will relapse on or after treatment with these drugs and various mechanisms behind this resistance to novel agents have been described. In this review, we present the current evidence on resistance to novel agents, discuss approaches to prevent its development and provide guidance on the treatment of patients who have already acquired resistance. The approval of Bruton's tyrosine kinase (BTK) inhibitors such as ibrutinib and acalabrutinib and the Bcl-2 inhibitor venetoclax have revolutionized the treatment of chronic lymphocytic leukemia (CLL). While these novel agents alone or in combination induce long lasting and deep remissions in most patients with CLL, their use may be associated with the development of clinical resistance. In this review, we elucidate the genetic basis of acquired resistance to BTK and Bcl-2 inhibition and present evidence on resistance mechanisms that are not linked to single genomic alterations affecting these target proteins. Strategies to prevent resistance to novel agents are discussed in this review with a special focus on new combination therapies

Sequential and combination treatments with novel agents in chronic lymphocytic leukemia

Chemoimmunotherapy has been the standard of care for patients with chronic lymphocytic leukemia for a long time. However, over the last few years, novel agents have produced unprecedented outcomes in treatment-naive and relapsed/refractory chronic lymphocytic leukemia. With the advent of these targeted agents, treatment options have diversified very considerably and new questions have emerged. For example, it is unclear whether these novel agents should be used as sequential monotherapies until disease progression or whether they should preferably be combined in time-limited treatment regimens aimed at achieving deep and durable remissions. While both approaches yield high response rates and long progression-free and overall survival, it remains challenging to identify patients individually for the optimal concept. This review provides guidance in this decision process by presenting evidence on sequential and combined use of novel agents and discussing the advantages and drawbacks of these two approaches

Relapsed disease and aspects of undetectable MRD and treatment discontinuation

Continuous treatment vs fixed duration of monotherapies and combinations of targeted agents are treatment options in relapsed chronic lymphocytic leukemia. The optimal choice of relapse treatment is dependent on the prior frontline therapy, duration of remission after frontline, genetic markers, and patients' condition, including age and comorbidities. Combination therapies may result in deep responses with undetectable minimal residual disease (uMRD). Although uMRD is an excellent predictive marker for disease progression, it is rarely used in clinical practice and needs additional evaluation in clinical trials before discontinuation of therapy should be guided according to uMRD

COVID-19 complicated by parainfluenza co-infection in a patient with chronic lymphocytic leukemia

The number of people suffering from the new coronavirus SARS-CoV-2 continues to rise. In SARS-CoV-2, superinfection with bacteria or fungi seems to be associated with increased mortality. The role of co-infections with respiratory viral pathogens has not yet been clarified. Here, we report the course of COVID-19 in a CLL patient with secondary immunodeficiency and viral co-infection with parainfluenza

Pooled analysis of first-line treatment with targeted agents in patients with chronic lymphocytic leukemia aged 80 years and older

Patients aged 80 years and older make up a fifth of patients with CLL but are underrepresented in clinical trials. We analyzed the outcomes of these patients treated with targeted agents in the front-line setting in six trials of the German CLL Study Group. Targeted agents included venetoclax, ibrutinib, and idelalisib, mainly used in combination with anti-CD20 antibodies. Among 716 patients, 33 matched the selection criteria (5%). Of those, the majority had relevant comorbidity, organ dysfunctions, and/or high-/very high-risk disease. The overall response rate was 73%. The median progression-free survival was 49.2 months compared with those not reached in younger patients. There were 11 documented deaths of which two were deemed related to therapy. Additional results including 40 patients treated with BTK-inhibitors from the GCLLSG registry suggest that treatment with targeted agents is feasible and effective. Dedicated studies are warranted for this particular subgroup of patients