While Trastuzumab deruxtecan (TDXD) is effective in HER2-low breast cancer, there is no evidence that it benefits patients with HER2-low or HER2-intermediate (IHC 2+/FISH negative) gastric cancer. Its use should be strictly limited to truly HER2-positive cases in this disease.

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.

Data from DESTINY-Breast09 shows TDXD plus pertuzumab dramatically improved progression-free survival in first-line metastatic HER2+ breast cancer. This unprecedented efficacy raises new questions about optimal treatment duration and the potential for de-escalated maintenance therapy after induction.

Positive data from both DESTINY-Breast09 (TDXD-based) and PATINA (CDK4/6i maintenance) create a new dilemma. With similar PFS outcomes, the first-line choice for metastatic HER2+/HR+ patients now hinges on toxicity profiles and patient preference rather than a single efficacy winner.

The DESTINY-Breast11 trial showed a neoadjuvant regimen of TDXD followed by THP achieved a 67.3% pathologic complete response (pCR) rate in high-risk HER2+ breast cancer. This is the highest pCR rate seen in a registrational trial, signaling a potential new standard of care.

Standard cancer surgery often removes lymph nodes—the factories producing immune cells. Administering immunotherapy *before* this destructive process is critical. It arms the immune system while it is still intact and capable of mounting a powerful, targeted response against the tumor.

A subtle finding in the DESTINY-Breast11 trial, where TDXD alone underperformed TDXD followed by THP, suggests that taxane-based chemotherapy might remain effective even after a patient's HER2-positive cancer becomes resistant to the antibody-drug conjugate TDXD.

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.

Modern breast cancer treatment has shifted from a 'one-size-fits-all' aggressive approach to a highly individualized one. By de-escalating care—doing smaller surgeries, minimizing radiation, and sometimes omitting chemotherapy or lymph node biopsies—clinicians can achieve better outcomes with fewer long-term complications for patients with favorable disease characteristics.