Patients on targeted therapy often become anxious about dose reductions, fearing the treatment will lose its effectiveness. Clinicians should explain that these drugs are developed with a therapeutic buffer, ensuring that even at a reduced dose, the drug is still effectively hitting its target while improving tolerability.

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.

When managing side effects from highly effective therapies like MEK inhibitors, it's often better to temporarily hold treatment and then resume at the original dose rather than immediately dose-reducing. This strategy maintains dose intensity, which is critical for maximizing the drug's therapeutic benefit.

A subgroup analysis from Capitello-291 suggests patients treated with capivasertib in the first-line setting experienced less diarrhea and rash than those in later lines. This aligns with a broader trend where heavily pre-treated patients exhibit poorer drug tolerance. This finding supports considering potent targeted agents earlier in the treatment sequence to potentially improve tolerability and outcomes.

To improve long-term tolerability of amivantamab, some experts advocate for a "marathon, not a sprint" approach. This involves aggressive dose holds or reductions at the earliest signs of toxicity, even low-grade, to prevent side effects from escalating and ensure patients can remain on effective therapy longer.

For patients with significant comorbidities like cardiovascular disease, proactively starting lenvatinib at a reduced dose (e.g., 14mg instead of 20mg) is a practical strategy to mitigate anticipated severe toxicities from the outset.

Data on Enfortumab Vedotin suggests that for modern therapies, maintaining patients on treatment longer via a lower, more tolerable starting dose is more important than administering the maximum labeled dose upfront, a concept inherited from the cytotoxic chemotherapy era.

Concerns over arterial events caused physicians to start CML patients on lower, less effective doses of ponatinib. Data shows a start-high (45mg) then reduce strategy is more effective for disease control and safely mitigates side effect risks, contrary to clinical practice.

Clinicians recommend starting lenvatinib at the full 20mg dose rather than escalating from a lower dose. This ensures therapeutic levels are reached. They then dose-reduce aggressively as needed. Starting low risks falsely concluding the drug is ineffective if the patient tolerates a suboptimal dose without response.