Biological and Clinical Insight from Analysis of the Tumor B-Cell Receptor Structure and Function in Chronic Lymphocytic Leukemia

Activity of venetoclax in patients with relapsed or refractory chronic lymphocytic leukaemia: analysis of the VENICE-1 multicentre, open-label, single-arm, phase 3b trial

BACKGROUND

Most patients with chronic lymphocytic leukaemia progress after treatment or retreatment with targeted therapy or chemoimmunotherapy and have limited subsequent treatment options. Response levels to the single-agent venetoclax in the relapsed setting is unknown. We aimed to assess venetoclax activity in patients with or without previous B-cell receptor-associated kinase inhibitor (BCRi) treatment.

METHODS

This multicentre, open-label, single-arm, phase 3b trial (VENICE-1) assessed activity and safety of venetoclax monotherapy in adults with relapsed or refractory chronic lymphocytic leukaemia, stratified by previous exposure to a BCRi. Eligible participants were aged 18 years or older with previously treated relapsed or refractory chronic lymphocytic leukaemia. Presence of del(17p) or TP53 aberrations and previous BCRi treatment were permitted. Patients received 5-week ramp-up to 400 mg of oral venetoclax once daily and were treated for up to 108 weeks, with 2 years follow-up after discontinuation, or optional extended access. The primary activity endpoint was complete remission rate (complete remission or complete remission with incomplete marrow recovery) in BCRi-naive patients. Analyses used the intent-to-treat (ie, all enrolled patients, which coincided with those who received at least one dose of venetoclax). This study was registered with ClinicalTrials.gov, NCT02756611, and is complete.

FINDINGS

Between June 22, 2016, and March 11, 2022, we enrolled 258 patients with relapsed or refractory chronic lymphocytic leukaemia (180 [70%] were male; 252 [98%] were White; 191 were BCRi-naive and 67 were BCRi-pretreated). Median follow-up in the overall cohort was 49·5 months (IQR 47·2-54·1), 49·2 months (47·2-53·2) in the BCRi-naive group, and 49·7 months (47·4-54·3) in the BCRi-pretreated group. Of 191 BCRi-naive patients, 66 (35%; 95% CI 27·8-41·8) had complete remission or complete remission with incomplete marrow recovery. 18 (27%; 95% CI 16·8-39·1) of 67 patients in the BCRi-pretreated group had complete remission or complete remission with incomplete marrow recovery. Grade 3 or worse treatment-emergent adverse events were reported in 203 (79%) and serious adverse events were reported in 136 (53%) of 258 patients in the overall cohort. The most common treatment-emergent adverse event was neutropenia (96 [37%]) and the most common and serious adverse event was pneumonia (21 [8%]). There were 13 (5%) deaths reported due to adverse events; one of these deaths (autoimmune haemolytic anaemia) was possibly related to venetoclax. No new safety signals were identified.

INTERPRETATION

These data demonstrate deep and durable responses with venetoclax monotherapy in patients with relapsed or refractory chronic lymphocytic leukaemia, including BCRi-pretreated patients, suggesting that venetoclax monotherapy is an effective strategy for treating BCRi-naive and BCRi-pretreated patients.

FUNDING

AbbVie.

Phase I/II results of ceralasertib as monotherapy or in combination with acalabrutinib in high-risk relapsed/refractory chronic lymphocytic leukemia

Background

Patients with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) have limited treatment options. Ceralasertib, a selective ataxia telangiectasia and Rad-3-related protein (ATR) inhibitor, demonstrated synergistic preclinical activity with a Bruton tyrosine kinase (BTK) inhibitor in TP53- and ATM-defective CLL cells. Acalabrutinib is a selective BTK inhibitor approved for treatment of CLL.

Objectives

To evaluate ceralasertib ± acalabrutinib in R/R CLL.

Design

Nonrandomized, open-label phase I/II study.

Methods

In arm A, patients received ceralasertib monotherapy 160 mg twice daily (BID) continuously (cohort 1) or 2 weeks on/2 weeks off (cohort 2). In arm B, patients received acalabrutinib 100 mg BID continuously (cycle 1), followed by combination treatment with ceralasertib 160 mg BID 1 week on/3 weeks off from cycle 2. Co-primary objectives were safety and pharmacokinetics. Efficacy was a secondary objective.

Results

Eleven patients were treated [arm A, n = 8 (cohort 1, n = 5; cohort 2, n = 3); arm B, n = 3 (acalabrutinib plus ceralasertib, n = 2; acalabrutinib only, n = 1)]. Median duration of exposure was 3.5 and 7.2 months for ceralasertib in arms A and B, respectively, and 15.9 months for acalabrutinib in arm B. Most common grade ⩾3 treatment-emergent adverse events (TEAEs) in arm A were anemia (75%) and thrombocytopenia (63%), with four dose-limiting toxicities (DLTs) of grade 4 thrombocytopenia. No grade ⩾3 TEAEs or DLTs occurred in arm B. Ceralasertib plasma concentrations were similar when administered as monotherapy or in combination. At median follow-up of 15.1 months in arm A, no responses were observed, median progression-free survival (PFS) was 3.8 months, and median overall survival (OS) was 16.9 months. At median follow-up of 17.2 months in arm B, overall response rate was 100%, and median PFS and OS were not reached.

Conclusion

Ceralasertib alone showed limited clinical benefit. Acalabrutinib plus ceralasertib was tolerable with preliminary activity in patients with R/R CLL, though findings are inconclusive due to small sample size.

Registration

NCT03328273.

Systematic Evaluation of Antigenic Stimulation in Chronic Lymphocytic Leukemia: Humoral Immunity as Biomarkers for Disease Evolution

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the Western world. Studies of CLL antibody reactivity have shown differential targets to autoantigens and antimicrobial molecular motifs that support the current hypothesis of CLL pathogenesis.

METHODS

In this study, we conducted a quantitative serum analysis of 7 immunoglobulins in CLL and monoclonal B-cell lymphocytosis (MBL) patients (bead-suspension protein arrays) and a serological profile (IgG and IgM) study of autoantibodies and antimicrobial antigens (protein microarrays).

RESULTS

Significant differences in the IgA levels were observed according to disease progression and evolution as well as significant alterations in IgG1 according to IGHV mutational status. More representative IgG autoantibodies in the cohort were against nonmutagenic proteins and IgM autoantibodies were against vesicle proteins. Antimicrobial IgG and IgM were detected against microbes associated with respiratory tract infections.

CONCLUSIONS

Quantitative differences in immunoglobulin serum levels could be potential biomarkers for disease progression. In the top 5 tumoral antigens, we detected autoantibodies (IgM and IgG) against proteins related to cell homeostasis and metabolism in the studied cohort. The top 5 microbial antigens were associated with respiratory and gastrointestinal infections; moreover, the subsets with better prognostics were characterized by a reactivation of Cytomegalovirus. The viral humoral response could be a potential prognosis biomarker for disease progression.

High surface IgM levels associate with shorter response to ibrutinib and BTK bypass in patients with CLL

Chronic lymphocytic leukemia (CLL) cells have variably low surface IgM (sIgM) levels/signaling capacity, influenced by chronic antigen engagement at tissue sites. Within these low levels, CLL with relatively high sIgM (CLLhigh) progresses more rapidly than CLL with low sIgM (CLLlow). During ibrutinib therapy, surviving CLL cells redistribute into the peripheral blood and can recover sIgM expression. Return of CLL cells to tissue may eventually recur, where cells with high sIgM could promote tumor growth. We analyzed time to new treatment (TTNT) following ibrutinib in 70 patients with CLL (median follow-up of 66 months) and correlated it with pretreatment sIgM levels and signaling characteristics. Pretreatment sIgM levels correlated with signaling capacity, as measured by intracellular Ca2+ mobilization (iCa2+), in vitro (r = 0.70; P < .0001). High sIgM levels/signaling strongly correlated with short TTNT (P < .05), and 36% of patients with CLLhigh vs 8% of patients with CLLlow progressed to require a new treatment. In vitro, capacity of ibrutinib to inhibit sIgM-mediated signaling inversely correlated with pretherapy sIgM levels (r = -0.68; P = .01) or iCa2+ (r = -0.71; P = .009). In patients, sIgM-mediated iCa2+ and ERK phosphorylation levels were reduced by ibrutinib therapy but not abolished. The residual signaling capacity downstream of BTK was associated with high expression of sIgM, whereas it was minimal when sIgM expression was low (P < .05). These results suggested that high sIgM levels facilitated CLL cell resistance to ibrutinib in patients. The CLL cells, surviving in the periphery with high sIgM expression, include a dangerous fraction that is able to migrate to tissue and receive proliferative stimuli, which may require targeting by combined approaches.