Due to cumulative toxicity concerns with TDXD, particularly ILD, clinicians express more comfort with the shorter 4-cycle neoadjuvant course from DESTINY-Breast11 than the prolonged 14-cycle adjuvant therapy in DESTINY-Breast05, favoring front-loading the treatment.

An ADC may show better response rates than chemotherapy, but its true benefit is compromised if toxicities lead to treatment discontinuation. As seen with failed PARP/IO combinations, if patients cannot tolerate a drug long enough, the regimen's overall effectiveness can become inferior to standard therapy.

Experts are cautious about using ADCs as long-term frontline maintenance therapy in ovarian cancer. Unlike oral PARPs, prolonged administration of these potent chemotherapies could cause cumulative toxicities, especially bone marrow suppression, potentially rendering patients unable to tolerate essential treatments upon relapse.

The PR21 trial showed better overall survival for docetaxel followed by Lutetium, despite similar progression-free survival. The likely reason is not drug superiority but patient behavior: a higher percentage of patients complete the second therapy when starting with chemo, highlighting how treatment fatigue significantly impacts survival.

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.

In the DB09 trial, the median progression-free survival (40 months) was double the median duration of TDXD treatment (20 months). This discrepancy suggests many patients discontinued the cytotoxic component and effectively entered a maintenance phase, validating the induction-maintenance model even within a continuous therapy trial design.

To mitigate long-term toxicity from TDXD, oncologists are proposing an "induction/maintenance" approach. Patients receive TDXD for an initial period to achieve maximal response, then switch to a less toxic maintenance regimen for a "chemotherapy holiday," improving quality of life.

Despite being the backbone for new combination therapies in trials like Matterhorn, the FLOT chemotherapy regimen has significant toxicity. Approximately 30% of patients discontinue treatment due to adverse events, and only half manage to complete the post-surgery adjuvant portion, posing a major clinical challenge in real-world settings.

As survival times for metastatic gastric cancer patients extend, managing long-term toxicity is paramount. Clinicians typically administer only 6-8 cycles of oxaliplatin to prevent severe, cumulative peripheral neuropathy, allowing for longer, better-tolerated maintenance therapy with biologics.