A review of the incidence of tumor lysis syndrome in patients with chronic lymphocytic leukemia treated with venetoclax and debulking strategies

We reviewed the literature (January 2010-June 2021) on the effectiveness of debulking strategies before venetoclax initiation in patients with chronic lymphocytic leukemia to reduce tumor burden, downgrade tumor lysis syndrome (TLS) risk, and avoid hospitalization. Low TLS incidence and reduced TLS risk based on tumor burden were reported following debulking in clinical trials. Real-world observational studies reporting debulking regimens recorded no TLS events, and those without debulking strategies had greater TLS incidence. Debulking prior to venetoclax considerably reduces TLS incidence. Further clinical trials and real-world studies may provide additional evidence on effectiveness of debulking in reducing TLS incidence and hospitalization need.

Antibody-drug conjugates for previously treated aggressive lymphomas: focus on polatuzumab vedotin

INTRODUCTION

Antibody-drug conjugates (ADCs) are immunoconjugates and comprise a monoclonal antibody that is chemically attached to a cytotoxic drug (or payload) via a stable chemical linker. Since the approval of the first ADC in 2000, there are now nine different approved agents and over 100 ADCs in the drug-development pipeline.

AREAS COVERED

This review briefly describes the ADCs approved for treatment of lymphoma and their distinguishing factors in terms of target, linker and payload. The clinical implications of the use of ADCs are also considered. Here, we focus on polatuzumab vedotin, an ADC targeted to CD79b, which is approved for the treatment of patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) who have received at least one (EU approval) or two (US approval) prior therapies and are not eligible for bone marrow transplantation. The characteristics of polatuzumab vedotin are discussed and clinical data are presented. The future of polatuzumab vedotin clinical development, and ADCs in general, are also considered.

EXPERT OPINION

ADCs represent a significant advance in the treatment of lymphoma. Polatuzumab vedotin has shown clinical efficacy and a tolerable safety profile in both first-line and R/R DLBCL; future studies are planned to further investigate this ADC.

Prognostic risk score for patients with relapsed or refractory chronic lymphocytic leukaemia treated with targeted therapies or chemoimmunotherapy: a retrospective, pooled cohort study with external validations

BACKGROUND

Clinically validated prognostic models for overall survival do not exist for patients with relapsed or refractory chronic lymphocytic leukaemia (CLL) who are on targeted therapies. We aimed to create a prognostic model to identify high-risk individuals who do not achieve a good outcome with available targeted therapies.

METHODS

In this retrospective, pooled cohort study, 2475 patients with CLL treated between June 22, 2012, and Sept 23, 2015, in six randomised trials of ibrutinib, idelalisib, and venetoclax, or at the Mayo Clinic CLL Database (MCCD) were included. Eligible patients had CLL, were previously treated, were aged 18 years or older, had ECOG performance status 0-1, and required further treatment as per the international workshop on CLL 2008 criteria. There was heterogeneity in other eligibility criteria. We evaluated 28 candidate factors known to affect the overall survival of these patients and applied univariate and multivariate analyses to derive the risk score in a training dataset (n=727) of patients treated with ibrutinib or chemoimmunotherapy. We validated the score in an internal-validation dataset (n=242) of patients treated with ibrutinib or chemoimmunotherapy and three external-validation datasets (idelalisib or chemoimmunotherapy dataset, n=897; venetoclax or chemoimmunotherapy dataset, n=389; and the MCCD [including patients treated with heterogeneous therapies], n=220), applying C-statistics as a measure of discrimination.

FINDINGS

The derived model consisted of four factors (one point each; serum β₂-microglobulin ≥5 mg/dL, lactate dehydrogenase >upper limit of normal, haemoglobin <110 g/L for women or <120 g/L for men, and time from initiation of last therapy <24 months), separating patients into low (score 0-1), intermediate (score 2-3), and high risk (score 4) groups. The risk score was prognostic for overall survival in the training dataset (CS=0·74, 95% CI 0·60-0·85, log-rank p<0·0001), and in the internal-validation (CS=0·79, 0·56-0·97, log-rank p=0·0003), and all three external-validation cohorts (idelalisib or chemoimmunotherapy: CS=0·71, 0·59-0·81, log-rank p<0·0001; venetoclax or chemoimmunotherapy: CS =0·76, 0·66-0·85, log-rank p=0·014; MCCD cohort: CS=0·61, 0·56-0·66), log-rank p<0·0001). The risk score is available on Calculate by QxMD.

INTERPRETATION

We present the first validated risk score to predict overall survival in patients with relapsed or refractory CLL treated with targeted therapy. The model is applicable to patients treated with all currently approved targeted therapies (ibrutinib, idelalisib, and venetoclax) and chemoimmunotherapy. This tool allows the identification of a well defined cohort of previously treated patients with CLL who are at high risk of death, and could be used in future prospective trials to test therapeutic options for these patients with an unmet clinical need.

FUNDING

Lymphoma Research Foundation, Lymphoma Research Fund (Andrew D Zelenetz), and National Institutes of Health/National Cancer Institute.

Evaluation of the CLL-IPI in relapsed and refractory chronic lymphocytic leukemia in idelalisib phase-3 trials

The CLL-IPI is a risk-weighted prognostic model for previously untreated patients with chronic lymphocytic leukemia (CLL), but has not been evaluated in patients with relapsed CLL or on novel therapies. We evaluated the CLL-IPI in 897 patients with relapsed/refractory CLL in 3 randomized trials testing idelalisib (PI3Kδ inhibitor). The CLL-IPI identified patients as low (2.2%), intermediate (12.8%), high (48.7%), and very high (36.2%) risk and was prognostic for survival (log-rank p < .0001; C-statistic 0.706). Of CLL-IPI factors, age >65, β2-microglobulin >3.5mg/L, unmutated immunoglobulin heavy chain variable region gene, and deletion 17p/TP53 mutation were independently prognostic, but Rai I-IV or Binet B/C was not. The CLL-IPI is prognostic for survival in relapsed CLL and with idelalisib therapy. However, low/intermediate risk is uncommon, and regression parameters of individual factors in this risk-weighted model appear different in relapsed CLL. Reassessment of the weighting of the individual variables might optimize the model in this setting.