Page 116 - Haematologica Vol. 110 - January 2025

ARTICLE - LIPA modulates venetoclax/TKI response in bpCML AB
M. Minhajuddin et al.
Figure 3. The venetoclax/ponatinib combination targets bulk cells and the leukemia stem cell compart- ment in a mouse model of blast phase T315I-mutant chronic myeloid leukemia. (A, B) T315I-mutant GY+ leukemia cells were treated in vitro with venetoclax (100 nM), ponatinib (100 nM) and their combination for 24 hours and viability measured rel- ative to vehicle control in bulk leu- kemia cells (A) and the leukemia stem cell compartment (Lin–Sca1+) (B). (C, D) Similarly, leukemic mice were treated with vehicle, venetoclax alone (100 mg/kg/day, oral gavage), ponatinib alone (10 mg/kg/day, oral gavage) and their combination for 5 days starting at day 7 after trans- plantation of leukemia. Mice were sacrificed at day 12 after the trans- plantation and their tissues were harvested to determine bulk leuke- mia burden (C) and quantitation of the leukemia stem cell compartment (Lin–Sca1+) (D) in the bone marrow. (E) Leukemic mice were treated with vehicle, venetoclax alone, ponatinib alone and their combination, as de- scribed above. Survival of control and treated leukemic mice (N=8) was monitored and mice were sac- rificed upon demonstration of mor- bid symptoms. Error bars denote mean ± standard deviation from triplicate experiments. Statistical analyses were performed using a Student t test. *P≤0.05, **P≤0.01, ***P≤0.001. Ven/Pona: venetoclax/ ponatinib combination; LSC: leuke- mia stem cells.
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of LSC functionality as a result of dual drug treatment, compared to either drug alone. We also performed sec- ondary engraftment from the cohort injected with bpCML1. The cells from primary engrafted mice, normalized to the percent of human cells from each treated group, were in- jected into the tail veins of secondary recipient mice. Mice were sacrificed after 12 weeks, and human hematopoietic engraftment was evaluated by flow cytometry. As can be seen in Figure 4D, E, the cells from the ven/dasa-treated group failed to engraft in secondary recipients, thereby demonstrating eradication of the LSC compartment. To further test the impact of ven/dasa on LSC function in vi- vo, primary human bpCML cells from one more case were
transplanted into immunocompromised NSG-S mice; as shown in Figure 4F, a significant reduction in tumor burden was observed in the ven/dasa-treated cohort. In contrast, treatment of CD34-enriched normal hematopoietic stem cells with similar doses of single agents or ven/dasa did not result in significant cell death and had no effect on colony formation (Online Supplementary Figure S3E, F), demonstrating a strong LSC-specific effect.
Lysosomal mechanisms influence the response to venetoclax and dasatinib in murine blast phase chronic myeloid leukemia
The collective results from murine models of bpCML show
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