February 25, 2019
I’m a very expensive wonder drug.
What molecule am I?
Image of Larotrectinib 3D Image of Larotrectinib

Larotrectinib (tradename Vitrakvi) is a cancer drug that was discovered by Array BioPharma (Boulder, CO) in the 2000s. In 2013, Array licensed it to Loxo Oncology (Stamford, CT, and South San Francisco, CA). The drug was jointly developed by Loxo (now part of Eli Lilly [Indianapolis]) and Bayer AG (Leverkusen, Germany). In 2018, the US Food and Drug Administration approved larotrectinib for treating cancer patients with a certain genetic marker.

Larotrectinib is the second drug (after Merck’s Keytruda), and the first small molecule, to be approved as a “tissue-agnostic” drug by the FDA. Tissue-agnostic means that the drug is not directed at cancers in specific organs, but rather at cancers caused by particular genetic mutations.

One type of gene mutation produces tumors resulting from the fusion of enzymes in the tropomyosin kinase (TRK) family. Larotrectinib inhibits TRK fusions and shrinks tumors produced by many types of cancer.

As always, there’s a catch. Vitrakvi is outrageously expensive. The Loxo–Bayer partnership has set the monthly wholesale acquisition cost of Vitrakvi pills at US$32,800. The price of the liquid formulation (primarily for children) is somewhat lower at $11,000. The companies justify these prices because of the rarity of patients with TRK fusion mutations.

Larotrectinib hazard information

GHS classification*: skin irritation, category 2
H315—Causes skin irritationChemical Safety Warning
GHS classification: skin sensitization, category 1
H317—May cause an allergic skin reactionChemical Safety Warning
GHS classification: serious eye damage/eye irritation, category 1
H318—Causes serious eye damageChemical Safety Warning
GHS classification: Respiratory sensitization, category 1
H334—May cause allergy or asthma symptoms or breathing difficulties if inhaledChemical Safety Warning
GHS classification: specific target organ toxicity, single exposure, respiratory tract irritation, category 3
H335—May cause respiratory irritationChemical Safety Warning
GHS classification: germ-cell mutagenicity, category 2
H341—Suspected of causing genetic defectsChemical Safety Warning
GHS classification: reproductive toxicity, category 2
H361—Suspected of damaging fertility or the unborn childChemical Safety Warning
GHS classification: specific target organ toxicity, single exposure, category 1
H370—Causes damage to organsChemical Safety Warning
GHS classification: hazardous to the aquatic environment, long-term hazard, category 4
H413—May cause long-lasting harmful effects to aquatic life

*Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

Larotrectinib fast facts

CAS Reg. No.1223403-58-4
Empirical formulaC21H22F2N6O2
Molar mass428.44 g/mol
AppearanceYellow powder
Melting pointUnavailable
Water solubilityInsoluble


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