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Pharmacological and Protein Profiling Suggests Venetoclax (ABT-199) as Optimal Partner with Ibrutinib in Chronic Lymphocytic Leukemia.

ABSTRACT: PURPOSE:Bruton's tyrosine kinase (BTK) is a critical enzyme in the B-cell receptor pathway and is inhibited by ibrutinib due to covalent binding to the kinase domain. Though ibrutinib results in impressive clinical activity in chronic lymphocytic leukemia (CLL), most patients achieve only partial remission due to residual disease. We performed a pharmacologic profiling of residual circulating CLL cells from patients receiving ibrutinib to identify optimal agents that could induce cell death of these lymphocytes. EXPERIMENTAL DESIGN:Ex vivo serial samples of CLL cells from patients on ibrutinib were obtained prior and after (weeks 2, 4, and 12) the start of treatment. These cells were incubated with PI3K inhibitors (idelalisib or IPI-145), bendamustine, additional ibrutinib, or BCL-2 antagonists (ABT-737 or ABT-199), and cell death was measured. In vitro investigations complemented ex vivo studies. Immunoblots for BTK signaling pathway and antiapoptotic proteins were performed. RESULTS:The BCL-2 antagonists, especially ABT-199, induced high cell death during ex vivo incubations. In concert with the ex vivo data, in vitro combinations also resulted in high cytotoxicity. Serial samples of CLL cells obtained before and 2, 4, 12, or 36 weeks after the start of ibrutinib showed inhibition of BTK activity and sensitivity to ABTs. Among the three BCL-2 family antiapoptotic proteins that are overexpressed in CLL, levels of MCL-1 and BCL-XL were decreased after ibrutinib while ABT-199 selectively antagonizes BCL-2. CONCLUSIONS:Our biologic and molecular results suggest that ibrutinib and ABT-199 combination should be tested clinically against CLL.

SUBMITTER: Cervantes-Gomez F

PROVIDER: S-EPMC4537801 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Pharmacological and Protein Profiling Suggests Venetoclax (ABT-199) as Optimal Partner with Ibrutinib in Chronic Lymphocytic Leukemia.

Cervantes-Gomez Fabiola F Lamothe Betty B Woyach Jennifer A JA Wierda William G WG Keating Michael J MJ Balakrishnan Kumudha K Gandhi Varsha V

Clinical cancer research : an official journal of the American Association for Cancer Research 20150331 16

<h4>Purpose</h4>Bruton's tyrosine kinase (BTK) is a critical enzyme in the B-cell receptor pathway and is inhibited by ibrutinib due to covalent binding to the kinase domain. Though ibrutinib results in impressive clinical activity in chronic lymphocytic leukemia (CLL), most patients achieve only partial remission due to residual disease. We performed a pharmacologic profiling of residual circulating CLL cells from patients receiving ibrutinib to identify optimal agents that could induce cell de ...[more]

PMID: 25829398

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Project description:B-cell receptor (BCR) signaling pathway and Bcl-2 family prosurvival proteins, specifically Bcl-2 and Mcl-1, are functional in the pathobiology of chronic lymphocytic leukemia (CLL). A pivotal and apical molecule in the BCR pathway is Bruton's tyrosine kinase (BTK). Together, BTK, Bcl-2, and Mcl-1 participate in the maintenance, migration, proliferation, and survival of CLL cells. Several ongoing and published clinical trials in CLL reported high rates of remission, namely, undetectable measurable residual disease (u-MRD) status with combined BTK inhibitor ibrutinib and Bcl-2 antagonist, venetoclax. While the majority of patients achieve complete remission with undetectable-measurable residual disease, at least one third of patients do not achieve this milestone. We hypothesized that cells persistent during ibrutinib and venetoclax therapy may be sensitive to combined venetoclax and Mcl-1 inhibitor, AMG-176. To test this hypothesis, we took peripheral blood samples at baseline, after Cycle 1 and Cycle 3 of ibrutinib monotherapy, after one week and 1 cycle of ibrutinib plus venetoclax therapy. These serial samples were tested for pharmacodynamic changes and treated in vitro with AMG-176 or in combination with venetoclax. Compared to C1D1 cells, residual cells during ibrutinib and venetoclax treatment were inherently resistant to endogenous cell death. Single agent exposure induced some apoptosis but combination of 100 nM venetoclax and 100 or 300 nM of AMG-176 resulted in 40-100% cell death in baseline samples. Cells obtained after four cycles of ibrutinib and one cycle of venetoclax, when treated with such concentration of venetoclax and AMG-176, showed 10-80% cell death. BCR signaling pathway, measured as autophosphorylation of BTK was inhibited throughout therapy in all post-therapy samples. Among four anti-apoptotic proteins, Mcl-1 and Bfl-1 decreased during therapy in most samples. Proapoptotic proteins decreased during therapy. Collectively, these data provide a rationale to test Mcl-1 antagonists alone or in combination in CLL during treatment with ibrutinib and venetoclax.

Project description:ImportanceOral targeted therapies have advanced the treatment of chronic lymphocytic leukemia (CLL). These therapies include Bruton tyrosine kinase inhibitors, used as monotherapy, and the Bcl-2 inhibitor venetoclax, typically combined with the CD20 monoclonal antibody. Preclinical studies have shown synergy between Bruton tyrosine kinase inhibitors and the Bcl-2 inhibitor venetoclax.ObjectiveTo examine the rate of complete remission, complete remission with incomplete count recovery, and bone marrow-undetectable measurable residual disease (U-MRD) after treatment with the combination of ibrutinib and venetoclax.Design, setting, and participantsA single-center, phase 2 nonrandomized trial enrolled patients from August 17, 2016, to June 5, 2018. Participants included previously untreated patients with CLL who met International Workshop on CLL 2008 criteria for treatment indication. Patients were required to have at least 1 of the following features: del(17p), TP53-mutated CLL, del(11q), unmutated immunoglobulin heavy-chain variable gene, or age 65 years or older.InterventionsTherapy consisted of ibrutinib, 420 mg/d, monotherapy for 3 cycles, thereafter combined with venetoclax (standard weekly dose ramp-up to 400 mg/d) for a total of 24 cycles of combination treatment. Responses were assessed at serial points according to International Workshop on CLL 2008 criteria. Measurable residual disease (MRD) was assessed by multicolor flow cytometry with a sensitivity of 10-4.Main outcomes and measuresOutcomes included complete remission, complete remission with incomplete count recovery, and bone marrow U-MRD rate.ResultsEighty patients (57 [71%] men) were treated; median age was 65 years (range, 26-83 years). The median follow-up for all 80 patients was 38.5 months (range, 5.6-51.1 months). Five patients discontinued the study during the ibrutinib monotherapy phase; the remaining 75 patients received combination therapy. On an intent-to-treat analysis of combined treatment, 45 (56%) patients achieved bone marrow U-MRD remission at 12 cycles and 53 (66%) patients achieved bone marrow U-MRD remission at 24 cycles. Overall, 60 (75%) patients achieved bone marrow U-MRD remission as their best response. Responses were seen across all high-risk subgroups, independent of the immunoglobulin heavy-chain variable gene mutation status, fluorescence in situ hybridization category, or TP53 mutation. The 3-year progression-free survival was 93%, and 3-year overall survival was 96%. No patient had CLL progression; 2 patients developed Richter transformation.Conclusions and relevanceThe findings of this study suggest that combination therapy with ibrutinib and venetoclax might be beneficial for previously untreated patients with CLL. Remissions appeared to be durable during a follow-up of more than 3 years, with activity seen across high-risk disease subgroups, including those with del(17p)/TP53-mutated CLL.Trial registrationClinicalTrials.gov Identifier: NCT02756897.

Dataset Information

Pharmacological and Protein Profiling Suggests Venetoclax (ABT-199) as Optimal Partner with Ibrutinib in Chronic Lymphocytic Leukemia.

Publications

Pharmacological and Protein Profiling Suggests Venetoclax (ABT-199) as Optimal Partner with Ibrutinib in Chronic Lymphocytic Leukemia.

Similar Datasets

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