Dr. Lotus Alphonsus

Post-op adjuvant imatinib, which is a tyrosine kinase inhibitor, can be used in intermediate to high-risk patients for three years, according to a recent trial.

For metastatic or unresectable GIST, the first line is imatinib, 400 milligrams per day.

If they have an exon 9 mutation, 800 milligrams per day can be considered.

You always need to confirm the genotype.

Always follow up with mutation testing before initiating imatinib.

Certain mutations, like the PDGFRAD842V, are resistant to imatinib.

remember to monitor for imatinib side effects such as hepatotoxicity and cytopenias.

There are other second- and third-line treatments, one of which would be sunitinib.

These alternatives are important options in case of resistance to imatinib, which may occur due to secondary mutations.

Of note, GIST can recur years later, so high-risk patients do require imaging follow-up for up to 10 years.

It's now time for our Medicine Minute.

In 2002, a landmark NEJM trial called the B2222 trial by Dimitri et al.

showed that imatinib, a tyrosine kinase inhibitor originally developed for chronic myeloid leukemia, could be used to treat GIST with remarkable success.

Before this, advanced GIST had a dismal prognosis with limited treatment options and poor survival rates.

The study showed an over 50% response rate with imatinib in metastatic GISTs.

Imatinib works by targeting mutations in a KIT proto-oncogene, which are found in about 85% of GISTs.

By inhibiting this tyrosine kinase, imatinib essentially turned off the driver for tumor growth.

The trial not only extended survival, but also redefined GIST as the poster child for targeted therapy in solid tumors.

It was one of the first real-world proofs that targeting a specific genetic mutation could dramatically alter a patient's outcome.

This study laid the groundwork for precision oncology and inspired a wave of research into molecular profiling and targeted drugs.