A key side effect of the FGFR inhibitor erdafitinib is central serous retinopathy, presenting as blurred vision. Standard of care involves a baseline ophthalmologic exam before starting treatment. If blurred vision occurs, treatment should be held immediately, but the condition is typically reversible and manageable with dose reduction.

Due to fedratinib's significant GI side effect profile and the logistical difficulty of measuring thiamine levels, clinicians should proactively provide patients with thiamine supplements, anti-emetics, and anti-diarrheal therapies. Instructing patients to take the drug with food can also help mitigate GI toxicity.

Broad-spectrum RAS-on inhibitors like daraxonrasib present skin toxicity as a dose-limiting side effect. However, this rash is clinically distinct from that caused by EGFR inhibitors. It is often manageable with brief treatment interruptions, frequently without requiring dose reductions, and patients tend to acclimate to it over time.

While better tolerated than chemotherapy, daraxon-rasib's unique toxicity profile (rash, stomatitis) requires a clinical management shift. Oncologists must proactively use strategies like prophylactic antibiotics, a departure from managing typical chemotherapy-induced myelosuppression.

Although 22% of patients experienced severe (Grade 3) mucositis, the treatment discontinuation rate due to adverse events was only about 3%. This disparity highlights that the side effect, while serious, was effectively managed with proactive dose reductions, preventing it from being a treatment-limiting factor for most patients.

A critical reason patients stop ADC treatments is the burden of side effects like skin toxicity or GI issues, not just disease progression. This underscores the urgent need to develop ADCs with better safety profiles, enabling patients to stay on effective therapy longer.

A real-world analysis of pemigatinib reported low rates of dose reduction or discontinuation. This may be misleading, as the toxicities of FGFR inhibitors (e.g., nail, skin, eye issues) are cumulative and worsen over extended periods. The study's shorter follow-up likely didn't capture the full long-term safety profile of the drug.

New targeted therapies like Zanidatamab and Zolbetuximab show great promise but cause significant side effects like diarrhea and nausea. Their successful clinical adoption hinges on proactive management using detailed guidelines and prophylactic medications, as toxicity can be severe enough to force treatment discontinuation despite the drug's efficacy.

The side effect profile of capivasertib is front-loaded. Key toxicities like diarrhea and rash appear quickly, leading to the majority (63%) of drug discontinuations occurring within the first three months. This highlights a critical window for proactive management and patient education to improve adherence.