How would you approach systemic management of a patient with an early aggressive metastatic relapse of previously early stage triple negative disease in breast only but now with multiple distant metastatic sites (including contralateral breast) which is now high ER expressing?

There isn't sufficient information to answer your question succinctly. Did she receive neoadjuvant chemotherapy, and, if so, how did she respond? Have you biopsied a metastatic site other than the contralateral breast? if not, you should, to assess its ER expression. Even if she is PD-L1 positive, t...