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.

Clinical trials with zanidatumab revealed significant diarrhea primarily in the first cycle. The successful management strategy involves mandatory loperamide twice daily for the first seven days to improve tolerability and prevent treatment discontinuation, a crucial implementation pearl.

The failure of an adjuvant trial for the TKI pazopanib was likely caused by a protocol change that reduced the dose to manage transaminitis. While well-intentioned to improve tolerability and adherence, the lower dose was sub-therapeutic. This serves as a critical lesson that managing side effects by compromising dose can nullify a drug's potential efficacy.

If gastroesophageal cancer does not respond to first-line zolbetuximab, experts advise against continuing it with a new chemo backbone. This is based on tumor heterogeneity and parallels with a negative trial of continuing trastuzumab past progression in HER2+ disease.

For patients over 75 with metastatic gastric cancer, a common practice is to reduce the oxaliplatin dose from 85 to 65 mg/m² and universally omit the 5-FU bolus from the FOLFOX regimen. This pragmatic approach aims to maintain efficacy while minimizing toxicity in a more vulnerable population.

The HORIZON-GEA-01 trial for zanidatumab in gastric cancer mandated prophylactic loperamide (4mg BID) for all patients. This was necessary to manage the high rates of diarrhea (up to 80% of patients), a significant GI toxicity associated with the drug's mechanism of action.

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.

Clinicians are finding that forgoing the standard 800mg loading dose of zolbituximab and starting directly with the 600mg maintenance dose appears to mitigate acute gastrointestinal toxicity, particularly gastritis. This practical adjustment is being formally studied but is already used in practice to improve patient experience.

The Phase 2 TRAIT study suggests starting adjuvant abemaciclib at a lower dose and escalating over several weeks significantly reduces early discontinuations due to side effects like diarrhea. This strategy helps more patients get through the initial high-toxicity period and remain on the effective dose for the full two-year course.