A PHASE 1A/B DOSE ESCALATION STUDY OF THE MUTATION AGNOSTIC BTK/FLT3 INHIBITOR LUXEPTINIB (CG-806) IN PATIENTS WITH RELAPSED OR REFRACTORY B-CELL MALIGNANCIES
Author(s): ,
Felipe Samaniego
Affiliations:
Department of Lymphoma and Myeloma,The University of Texas MD Anderson Cancer Center,Houston,United States
,
M. Zach Koontz
Affiliations:
Pacific Cancer Care,Monterey,United States
,
Jose C Villasboas
Affiliations:
Division of Hematology, Department of Internal Medicine,Mayo Clinic,Rochester,United States
,
Ahad Ali Sadiq
Affiliations:
Fort Wayne Medical Oncology and Hematology,Fort Wayne,United States
,
Lindsey E Roeker
Affiliations:
Memorial Sloan Kettering Cancer Center,New York,United States
,
John M. Burke
Affiliations:
Rocky Mountain Cancer Centers,Aurora,United States
,
Mohamad Cherry
Affiliations:
Morristown Medical Center,Morristown,United States
,
Patrick Cobb
Affiliations:
St. Vincent Healthcare,Billings,United States
,
David Cosgrove
Affiliations:
Northwest Cancer Specialists / Compass Oncology,Vancouver,United States
,
Jason M. Melear
Affiliations:
Texas Oncology-Austin Midtown,,Austin,United States
,
Victor Priego
Affiliations:
Regional Cancer Care Associates,Hackensack,United States
,
Erin Reid
Affiliations:
Moores Cancer Center,University of California San Diego Health,San Diego,United States
,
Hongying Zhang
Affiliations:
Aptose Biosciences, Inc,San Diego,United States
,
Nasrin Rastgoo
Affiliations:
Aptose Biosciences, Inc,San Diego,United States
,
Khalid Benbatoul
Affiliations:
Aptose Biosciences, Inc,San Diego,United States
,
Yuying Jin
Affiliations:
Aptose Biosciences, Inc,San Diego,United States
,
Matthew Thayer
Affiliations:
Aptose Biosciences, Inc,San Diego,United States
,
Jotin Marango
Affiliations:
Aptose Biosciences, Inc,San Diego,United States
,
Stephen Howell
Affiliations:
Moores Cancer Center,University of California San Diego Health,San Diego,United States
,
William Rice
Affiliations:
Aptose Biosciences, Inc,San Diego,United States
Rafael Bejar
Affiliations:
Aptose Biosciences, Inc,San Diego,United States;Moores Cancer Center,University of California San Diego Health,San Diego,United States
EHA Library. Bejar R. 06/09/21; 325403; EP643
Rafael Bejar
Rafael Bejar
Contributions
Abstract
Presentation during EHA2021: All e-poster presentations will be made available as of Friday, June 11, 2021 (09:00 CEST) and will be accessible for on-demand viewing until August 15, 2021 on the Virtual Congress platform.

Abstract: EP643

Type: E-Poster Presentation

Session title: Chronic lymphocytic leukemia and related disorders - Clinical

Background
Luxeptinib (CG-806) is a potent, non-covalent oral inhibitor designed to target BTK and FLT3. It suppresses BCR signaling pathways (through inhibition of LYN, SYK, BTK, AKT, ERK) in cell lines and primary CLL cells, kills malignant B-cells insensitive to ibrutinib or venetoclax at low nM concentrations, and shows enhanced activity in combination with venetoclax. Luxeptinib is currently being evaluated in a Phase 1a/b trial in patients with relapsed or refractory B-cell malignancies (NCT03893682). 

Aims
Primary objectives are to assess the safety and tolerability of Luxeptinib and determine the recommended Phase 2 dose for future clinical trials in patients with R/R CLL/SLL or NHL. Key secondary objectives include elucidation of the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics, and evidence of antitumor activity.

Methods
Luxeptinib is administered continuously as oral capsules BID in 28-day cycles, in ascending cohorts of 3 patients. Treatment emergent adverse events (TEAEs) and tumor responses are evaluated per disease specific guidelines. 

Results
As of December 4, 2020, a total of 16 patients (age 65.8 ± 7.9 years, 9 CLL/SLL, 3 follicular lymphoma, 1 Richter’s transformation lymphoma, 1 Waldenstrom’s macroglobulinemia, 1 mantle cell lymphoma, 1 diffuse large B cell lymphoma) with a median of 3 prior systemic regimens (range of 1 - 12) have been treated with luxeptinib at doses of 150 mg (n=1), 300 mg (n=1), 450 mg (n=6), 600 mg (n=4) and 750 mg (n=4). The most common drug-related or possibly drug-related TEAEs included nausea in 6 (37.5%), vomiting in 5 (31.3%), diarrhea and neutropenia in 4 (25%) each, and fatigue in 3 (12.5%) patients. Drug related grade ≥ 3 TEAEs included neutropenia (n=3, 18.8%, no fevers were reported), thrombocytopenia, diarrhea, hypertension, and headache (n=1, 6.3% each). One patient, who had developed grade 2 hypertension during screening and prior to dosing on C1D1, experienced grade 4 hypertension after Luxeptinib treatment at 750 mg BID for 5 days. While this was considered a DLT per protocol, CG-806 plasma levels in this patient were lower than those observed in patients at this and lower dose levels. No drug-related hypertension has been observed in any other patient treated to date. The steady-state (Cmin) plasma levels of luxeptinib in patients treated with ≥ 600 mg BID were generally in the 1-2µM range and were sustained over multiple cycles. PD analysis demonstrated that Cmin of Luxeptinib in the plasma of patients treated with doses of 300 mg or higher significantly reduced levels of phosphorylated BTK, SYK, ERK and FLT3 in EOL-1 reporter cells in a plasma inhibitor activity assay, demonstrating multi-target engagement. All 3 CLL patients with elevated lymphocyte counts pre-treatment experienced on-target lymphocytosis upon initiation of luxeptinib therapy.

Conclusion
Luxeptinib has a favorable safety profile in patients treated with 150 mg to 600 mg BID over multiple cycles. A single DLT (grade 4 hypertension in one patient with pre-existing hypertension) led to expansion of the 750 mg dose level to 6 patients. Pharmacodynamic studies documented inhibition of SYK, BTK and ERK in the BCR signaling pathway. Enrollment of patients with R/R CLL/SLL and NHL at dose level 5 (750 mg) is ongoing and updated clinical data will be presented at the meeting. 

Keyword(s): Chronic lymphocytic leukemia, Non-Hodgkin's lymphoma, Refractory, Relapse

Presentation during EHA2021: All e-poster presentations will be made available as of Friday, June 11, 2021 (09:00 CEST) and will be accessible for on-demand viewing until August 15, 2021 on the Virtual Congress platform.

Abstract: EP643

Type: E-Poster Presentation

Session title: Chronic lymphocytic leukemia and related disorders - Clinical

Background
Luxeptinib (CG-806) is a potent, non-covalent oral inhibitor designed to target BTK and FLT3. It suppresses BCR signaling pathways (through inhibition of LYN, SYK, BTK, AKT, ERK) in cell lines and primary CLL cells, kills malignant B-cells insensitive to ibrutinib or venetoclax at low nM concentrations, and shows enhanced activity in combination with venetoclax. Luxeptinib is currently being evaluated in a Phase 1a/b trial in patients with relapsed or refractory B-cell malignancies (NCT03893682). 

Aims
Primary objectives are to assess the safety and tolerability of Luxeptinib and determine the recommended Phase 2 dose for future clinical trials in patients with R/R CLL/SLL or NHL. Key secondary objectives include elucidation of the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics, and evidence of antitumor activity.

Methods
Luxeptinib is administered continuously as oral capsules BID in 28-day cycles, in ascending cohorts of 3 patients. Treatment emergent adverse events (TEAEs) and tumor responses are evaluated per disease specific guidelines. 

Results
As of December 4, 2020, a total of 16 patients (age 65.8 ± 7.9 years, 9 CLL/SLL, 3 follicular lymphoma, 1 Richter’s transformation lymphoma, 1 Waldenstrom’s macroglobulinemia, 1 mantle cell lymphoma, 1 diffuse large B cell lymphoma) with a median of 3 prior systemic regimens (range of 1 - 12) have been treated with luxeptinib at doses of 150 mg (n=1), 300 mg (n=1), 450 mg (n=6), 600 mg (n=4) and 750 mg (n=4). The most common drug-related or possibly drug-related TEAEs included nausea in 6 (37.5%), vomiting in 5 (31.3%), diarrhea and neutropenia in 4 (25%) each, and fatigue in 3 (12.5%) patients. Drug related grade ≥ 3 TEAEs included neutropenia (n=3, 18.8%, no fevers were reported), thrombocytopenia, diarrhea, hypertension, and headache (n=1, 6.3% each). One patient, who had developed grade 2 hypertension during screening and prior to dosing on C1D1, experienced grade 4 hypertension after Luxeptinib treatment at 750 mg BID for 5 days. While this was considered a DLT per protocol, CG-806 plasma levels in this patient were lower than those observed in patients at this and lower dose levels. No drug-related hypertension has been observed in any other patient treated to date. The steady-state (Cmin) plasma levels of luxeptinib in patients treated with ≥ 600 mg BID were generally in the 1-2µM range and were sustained over multiple cycles. PD analysis demonstrated that Cmin of Luxeptinib in the plasma of patients treated with doses of 300 mg or higher significantly reduced levels of phosphorylated BTK, SYK, ERK and FLT3 in EOL-1 reporter cells in a plasma inhibitor activity assay, demonstrating multi-target engagement. All 3 CLL patients with elevated lymphocyte counts pre-treatment experienced on-target lymphocytosis upon initiation of luxeptinib therapy.

Conclusion
Luxeptinib has a favorable safety profile in patients treated with 150 mg to 600 mg BID over multiple cycles. A single DLT (grade 4 hypertension in one patient with pre-existing hypertension) led to expansion of the 750 mg dose level to 6 patients. Pharmacodynamic studies documented inhibition of SYK, BTK and ERK in the BCR signaling pathway. Enrollment of patients with R/R CLL/SLL and NHL at dose level 5 (750 mg) is ongoing and updated clinical data will be presented at the meeting. 

Keyword(s): Chronic lymphocytic leukemia, Non-Hodgkin's lymphoma, Refractory, Relapse

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