The GOG-B21 trial found that while adding pembrolizumab to chemotherapy benefits the dMMR subgroup, it paradoxically leads to worse outcomes in the pMMR subgroup. This highlights the critical need for molecular testing to avoid potential harm.

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.

Extrapolating from the metastatic setting, clinicians should anticipate that most patients on the 9-cycle perioperative EV-pembrolizumab regimen will require dose reductions or holds. Cumulative peripheral neuropathy is the primary driver, suggesting a need for proactive, individualized dose management rather than strict adherence to the trial's protocol.

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.

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.

In the REJOYCE ovarian-1 trial for RDXD, the 5.6 mg/kg dose was selected to move forward over a 6.4 mg/kg dose that showed a higher response rate (57%). The lower dose had significantly fewer serious adverse events and a lower rate of interstitial lung disease (ILD), demonstrating a crucial trade-off where safety and tolerability outweigh peak efficacy in late-stage development.

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.

Contrary to the assumption that combinations are more toxic, Lenvatinib/Belzutifan showed a different side effect profile, not a worse one, compared to single-agent Cabozantinib. The combo caused more anemia while Cabozantinib caused more diarrhea and skin toxicity, but treatment discontinuation rates were identical at 11% for both arms.

Although 60% of patients required a dose reduction for talazoparib, the expert argues for the higher starting dose. He believes it secures a more durable and long-lasting response, which is crucial, even if it necessitates later dose adjustments due to toxicity like anemia.