Larotrectinib

Breast Feeding; Lactation; Milk, Human; Antineoplastic Agents; Enzyme Inhibitors; Protein Kinase Inhibitors; Signal Transduction Inhibitors

EMA approved medicines: Human medicine

In early clinical trials in a total of 176 patients with various forms of solid tumors which had an NTRK gene fusion, elevations in serum aminotransferase levels occurred in 45% of patients treated with larotrectinib. Serum aminotransferase levels rose to above 5 times ULN in 6% of patients and led to early discontinuation in 2%. Serum aminotransferase elevations typically arose after 4 to 12 weeks of treatment, but usually without jaundice or alkaline phosphatase elevations. Most elevations resolved within 4 to 8 weeks and discontinuations were uncommon. Restarting larotrectinib at a reduced dose after resolution of the aminotransferase abnormalities was generally well tolerated and did not lead to recurrence of liver injury. Cases with jaundice and symptoms during larotrectinib therapy have not been reported, but the clinical experience with this kinase inhibitor has been limited and prelicensure clinical trials were carried out with careful clinical monitoring.

L - Antineoplastic and immunomodulating agents

QL - Antineoplastic and immunomodulating agents

In a broad panel of purified enzyme assays, larotrectinib inhibited TRKA, TRKB, and TRKC with IC50 values between 5-11 nM. One other kinase, TNK2, was inhibited at approximately 100-fold higher concentration. At doses that are nine-fold greater than the recommended adult dose, larotrectinib does not elicit any QTc interval prolongation that is clinically relevant. No dose adjustment is recommended for patients with renal impairment of any severity, but dose reductions are warranted in patients with moderate (Child-Pugh B) to severe (Child-Pugh C) hepatic impairment.

Tropomysoin receptor kinases (TRK) like TRKA, TRKB, and TRKC elicit activities that regulate the natural growth, differentiation, and survival of neurons when they interact with endogenous neutrotrophin ligands. TRKA, TRKB, and TRKC are themselves encoded by the NTRK1, NTRK2, and NTRK3 genes, respectively. It has been discovered that chromosomal rearrangements involving in-frame fusions of these genes with various partners, translocations in the TRK kinase domains, mutations in the TRK ligand-binding site, amplifications of NTRK, or the expression of TRK splice variants can result in constitutively-activated chimeric TRK fusion proteins that can act as oncogenic drivers that promote cell proliferation and survival in tumor cell lines. Subsequently, larotrectinib functions as an inhibitor of TRKs including TRKA, B, and C. In in vitro and in vivo tumor models, larotrectinib demonstrated anti-tumor activity in cells with constitutive activation of TRK proteins resulting from gene fusions, deletion of a protein regulatory domain, or in cells with TRK protein overexpression. Larotrectinib had minimal activity in cell lines with point mutations in the TRKA kinase domain, including the clinically identified acquired resistance mutation, G595R. Point mutations in the TRKC kinase domain with clinically identified acquired resistance to larotrectinib include G623R, G696A, and F617L.

Larotrectinib is metabolized predominantly by CYP3A4. Following oral administration of a single 100 mg dose of radiolabeled larotrectinib in healthy subjects, the major circulating drug components in plasma were unchanged larotrectinib (19%) and an O-linked glucuronide (26%).

PF9462I9HX

LAROTRECTINIB

Established Pharmacologic Class [EPC] - Kinase Inhibitor

Mechanisms of Action [MoA] - Tropomyosin Receptor Kinases Inhibitors

Larotrectinib is a Kinase Inhibitor. The mechanism of action of larotrectinib is as a Tropomyosin Receptor Kinases Inhibitor.

LAROTRECTINIB

The mean absolute bioavailability of larotrectinib capsules is approximately 34% (range: 32-37%). In adult patients who received larotrectinib capsules 100 mg twice daily, Cmax was achieved at about one hour after dosing and steady-state was reached within three days. The mean steady-state Cmax and AUC0-24h of larotrectinib capsules was 788 ng/mL and 4351 ng*h/mL, respectively. In healthy subjects, the AUC of the larotrectinib oral solution was similar to that of the capsules and the Cmax was 36% greater with the oral solution. As compared to a fasted state, the administration of larotrectinib in healthy subjects alongside a high-fat meal resulted in a similar AUC and a reduction in Cmax of 35%.

Following oral administration of a single 100 mg dose of radiolabeled larotrectinib in healthy subjects, 58% (5% unchanged) of the administered radioactivity was recovered in feces and 39% (20% unchanged) was recovered in urine.

Following intravenous administration to healthy subjects, the mean volume of distribution of larotrectinib at steady-state was approximately 48L.

The mean clearance CL/F of larotrectinib is 98 L/h.