How would you manage a patient with stage IV EGFR L858R mutation but with a debilitating drug rash from osimertinib?

I'm assuming that all methods of supportive care and dose reduction have been tried at this point (i.e. even with maximal supportive care, Dermatology referral, and osimertinib reduced to 40 mg PO daily), there is still intolerable rash. This is a difficult situation and there isn't much available i...