Would you continue pembrolizumab in a patient with BCG-refractory NMIBC with CIS who has a negative surveillance cystoscopy (including random biopsies) but positive urine cytology?  

More important priority at this point is to evaluate the positive cytology. If the random biopsies were done with white light cystoscopy only, I would consider blue light and repeat biopsies and would also evaluate the upper tracts and prostatic urethra.