Tyrosine kinase inhibitors (TKIs) have dramatically increased median overall survival for GIST patients from nine months to over seven years. Some patients have now been on therapy for over 20 years. This longevity transforms GIST into a chronic condition, making long-term side effect management and quality of life critical for maintaining treatment adherence and efficacy.
Unlike traditional chemotherapy dosed by body surface area, TKIs for GIST are dosed based on individual patient tolerance. Therapeutic drug monitoring of plasma levels has not proven effective. The standard approach is to start all patients at a recommended dose and then adjust based on side effects to find the highest tolerable dose that maintains efficacy.
For patients intolerant to standard TKI starting doses, a "crescendo" approach can be highly effective. This involves starting at a very low dose (e.g., 200mg every other day) and slowly increasing it over several weeks. This gradual escalation allows the body to acclimate, enabling patients to eventually tolerate the full target dose without unacceptable toxicity.
Current solid TKI pills, especially capsules, make fine-tuned dose adjustments difficult. A liquid formulation would offer crucial flexibility, allowing for precise dosing (e.g., 350mg instead of 400mg) to manage the dose-response relationship. It would also be ideal for patients with feeding tubes or GI issues who cannot tolerate or swallow solid pills, preventing treatment delays.