Preclinical Pharmacokinetic and Pharmacodynamic Evaluation of Dasatinib and Ponatinib in Lck-Activated T-Cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy in both children and adults, and novel therapies are much needed especially in patients with relapsed or refractory disease. Studies by us and other recently discovered that 44% of pediatric and 16% of adult T-ALL cases exhibit constitutively activation of preTCR-LCK signaling, rendering leukemia blasts exquisitely sensitive to dasatinib and ponatinib (NatCancer 2, 284-299, 2021). Monotherapy using these agents resulted in significant anti-leukemic efficacies invivo in patient-derived xenograft (PDX) models of T-ALL, pointing to the therapeutic potential of LCK inhibitor therapy in T-ALL. Therefore, comprehensive preclinical characterization of pharmacokinetic and pharmacodynamic profile of dasatinib and ponatinib in T-ALL is needed for designing human trials of these agents in this cancer.

To this end, we determined pharmacokinetics of dasatinib and ponatinib in PDX models of T-ALL, with LCK inhibition as the pharmacodynamic endpoint. Drug concentration in the plasma was measured using LC-MS at different time points (dasatinib, 6; ponatinib, 8 times) following a single dose. For the pharmacodynamic evaluation, pLCK (Y394) was quantified using Western blot. Pharmacokinetic modeling for each drug was performed based on a first-order absorption and linear elimination model, while the pharmacodynamics of pLCK in the presence of dasatinib or ponatinib were modeled with an indirect response model where the drug de-phosphorylates LCK.

With a single oral administration of dasatinib at 20 and 40 mg/kg, C_max was 102 and 366 ng/mL, T_max was 1.17 hours for both dosages, and AUC_0-inf was 499 and 1952 ng hr/mL, respectively. In contrast, a single oral dose of ponatinib at 15 and 30 mg/kg resulted in a C_max of 181 and 355 ng/mL, T_max of 3.04 and 3.08 hours, and AUC _0-inf of 1533 and 3010 ng hr/mL, respectively. In the dasatinib pharmacodynamic model, E_max was 3.6 (CV 26%), EC₅₀ was 19.9 ng/mL (CV 28%), and the maximum effect was 22% of the baseline. On the other hand, ponatinib showed slower and slightly longer effect with E_max of 4.6 (CV 12%), EC₅₀ of 38.8 ng/mL (CV 25%), and the maximum effect of 18% of the baseline. Using these exposure-response models, we then simulated the steady-state pharmacodynamic effects on LCK by dasatinib or ponatinib given at FDA approved dosages in human in a 7-day course of treatment. Dasatinib at 140 mg and ponatinib at 45 mg once a day were estimated to inhibit LCK by 50% or more for 22.3 and 24.0 hours per day, respectively, at the steady states.

Moreover, we developed a dasatinib-resistant T-ALL cell line model by continuous treatment with dasatinib, in which ponatinib retained its ability to inhibit LCK with cytotoxic effects. Interestingly, the cell model acquired the LCK T316I mutation, corresponding to the ABL1 T315I mutation in BCR-ABL1 ALL. Although it is unclear whether this mutation would occur in T-ALL patients undergoing dasatinib treatment, our findings point to the need for evaluating multiple LCK inhibitors as a treatment option.

In conclusion, we comprehensively characterized pharmacokinetic and pharmacodynamic profile of dasatinib and ponatinib in preclinical models of T-ALL, and our exposure-response modeling established human dosage levels for future trials of LCK inhibitor for this cancer.

Pui:Novartis: Other: Data monitoring committee; Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees. Konopleva:Stemline Therapeutics, F. Hoffman La-Roche; Janssen: Membership on an entity's Board of Directors or advisory committees; AbbVie, Genentech, F. Hoffman La-Roche, Stemline Therapeutics, Amgen, Forty-Seven, Kisoji; Janssen: Consultancy; Forty-Seven; F. Hoffman LaRoche: Honoraria; Reata Pharmaceuticals, Novartis and Eli Lilly: Patents & Royalties; AbbVie, Genentech, F. Hoffman La-Roche, Eli Lilly, Cellectis, Calithera, Ablynx, Stemline Therapeutics, Agios, Ascentage, Astra Zeneca; Rafael Pharmaceutical; Sanofi, Forty-Seven: Research Funding; Stocks, Reata Pharmaceuticals: Current equity holder in publicly-traded company. Jain:Dialectic Therapeutics: Research Funding; Precision Biosciences: Consultancy, Honoraria, Other: Travel Support, Research Funding; Genentech, Inc.: Consultancy, Honoraria, Other: Travel Support, Research Funding; Servier Pharmaceuticals LLC: Research Funding; Incyte Corporation: Research Funding; Cellectis: Honoraria, Research Funding; Newave: Research Funding; Adaptive Biotechnologies: Consultancy, Honoraria, Other: Travel Support, Research Funding; TG Therapeutics: Honoraria; Janssen Pharmaceuticals, Inc.: Consultancy, Honoraria, Other: Travel Support; Pharmacyclics, Inc.: Consultancy, Honoraria, Other: Travel Support, Research Funding; CareDx: Honoraria; Ipsen: Honoraria; MEI Pharma: Honoraria; BMS: Consultancy, Honoraria, Other: Travel Support, Research Funding; ADC Therapeutics: Research Funding; Cellectis: Honoraria, Research Funding; Takeda: Research Funding; AstraZeneca: Consultancy, Honoraria, Other: Travel Support, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Mingsight: Research Funding; Medisix: Research Funding; Loxo Oncology: Research Funding; Aprea Therapeutics: Research Funding; Fate Therapeutics: Research Funding; Beigene: Honoraria; TransThera Sciences: Research Funding; AbbVie: Consultancy, Honoraria, Other: Travel Support, Research Funding; Novalgen: Research Funding; Pfizer: Research Funding. Yang:Takeda Pharmaceutical Company: Research Funding.