The Victoria 1 trial reported "historically low" discontinuation rates for the PI3K inhibitor alpelisib. This indicates that oncologists have become significantly better at proactively managing the drug's known toxicities, such as hyperglycemia. This real-world clinical maturation has improved the drug's tolerability and practical utility since its initial approval studies.

For drugs like enovalisib and gedatolisib with high rates of stomatitis, prophylactic use of a dexamethasone mouth rinse from day one is critical. This preventative measure significantly reduces the incidence and severity of painful oral sores, improving treatment tolerability.

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.

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.

The enzalutamide arms saw discontinuation rates of 20-25% due to adverse events. This high rate reflects a different risk calculation for patients who feel healthy and are asymptomatic. Unlike in advanced disease where patients tolerate more toxicity, this population has a very low threshold for side effects, making early intervention a significant trade-off.

The discontinuation rate for pembrolizumab due to side effects was lower in the LITESPARK 022 trial compared to the earlier Keynote 564 trial (20%). This trend suggests that as clinicians gain more experience with immune checkpoint inhibitors, they are becoming more adept at managing immune-related adverse events, allowing more patients to complete their therapy.

Second-generation PI3K inhibitor enovalisib has a 7% discontinuation rate compared to 25% for its predecessor, alpelisib. This is due to a better toxicity profile (e.g., 6% vs. 33% high-grade hyperglycemia) and improved proactive side effect management by clinicians.

The LIDERA trial showed that while jiridestrant and standard therapies had similar adverse event profiles, patients on jiridestrant had significantly lower discontinuation rates. This highlights that a patient's subjective experience of tolerability is a more critical factor for long-term adherence than a simple list of side effects.

The TRAIL trial found starting abemaciclib at a low dose (50mg) and escalating every two weeks drastically improves tolerability. This approach reduced Grade 3 diarrhea from 7.8% in the pivotal trial to just 3.3% and lowered early discontinuation rates, allowing more patients to reach the full therapeutic dose and stay on treatment.