How would you manage a patient with ER+ HER-2+ metastatic disease on T-DM1 with NED for over 2 years, now with an isolated recurrence that is ER+ but HER-2 negative?

Odd presentation. Would talk to the pathologist about the receptors status and consider repeating those. If this is truly ER+ and HER2 negative, I would keep the T-DM1 going and add an AI