Entrectinib (Mechanism of Action)

In this article, we will discuss Entrectinib (Mechanism of Action). So, let’s get started.

Mechanism of Action

Entrectinib is an inhibitor of the tropomyosin receptor tyrosine kinases (TRK) TRKA, TRKB, and TRKC (encoded by the neurotrophic tyrosine receptor kinase [NTRK] genes NTRK1, NTRK2, and NTRK3, respectively), proto-oncogene tyrosine-protein kinase ROS1 (ROS1), and anaplastic lymphoma kinase (ALK) with IC50 values of 0.1 to 2 nM. Entrectinib also inhibits JAK2 and TNK2 with IC50 values > 5 nM. The major active metabolite of entrectinib, M5, showed similar in vitro activity against TRK, ROS1, and ALK. Fusion proteins that include TRK, ROS1, or ALK kinase domains can drive tumorigenic potential through hyperactivation of downstream signaling pathways leading to unconstrained cell proliferation. Entrectinib demonstrated in vitro and in vivo inhibition of cancer cell lines derived from multiple tumor types harboring NTRK, ROS1, and ALK fusion genes.

Entrectinib demonstrated steady-state brain-to-plasma concentration ratios of 0.4 – 2.2 in multiple animal species (mice, rats, and dogs) and demonstrated in vivo anti-tumor activity in mice with intracranial implantation of TRKA- and ALK-driven tumor cell lines.

Pharmacodynamics
Entrectinib exposure-response relationships and the time course of pharmacodynamic responses are unknown.

Cardiac Electrophysiology
Across clinical trials, 3.1% of 355 patients, who received Entrectinib at doses ranging from 100 mg to 2600 mg daily under fasting or fed conditions (75% received 600 mg orally once daily) and had at least one post-baseline ECG assessment, experienced QTcF interval prolongation of > 60 ms after starting Entrectinib and 0.6% had a QTc interval > 500 ms.

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