How would you modify adjuvant therapy for a patient with ER+ HER2+ breast CA with no response to neoadjuvant TCHP and develops pneumonitis on adjuvant TDM-1?

Retest tissue for Her2.

No data for cytotoxic chemo but consider ACx4 and adjuvant Traz/pertuz to complete a year and then perhaps Neratinib especially if ER+ive.