PK Sub-Study of QUILT-3.032 (CA ALT-803-01-16) and of QUILT-2.005 (CA ALT-803-01-14)

QUILT-3.032 is a Phase 2, open-label, single-arm, three-cohort, multicenter study of intravesical BCG plus ALT-803 in patients with BCG unresponsive high grade NMIBC. Patients will be enrolled into one of three study cohorts. Cohort A will enroll 80 patients who have histologically confirmed presence of BCG-unresponsive carcinoma in situ (CIS) [with or without Ta or T1 disease]. Cohort B will enroll 80 patients who have histologically confirmed BCG-unresponsive high-grade Ta or T1 disease. Cohort C will enroll up to 23 patients who also have histologically confirmed presence of BCG-unresponsive CIS [with or without Ta/T1 papillary disease]. Patients in Cohorts A and B will receive ALT-803 plus BCG combination treatment. Patients in Cohort C will receive ALT-803 alone. Enrollment of Cohort C will start once the enrollment of Cohort A is complete. Cohorts A, B, and C are independent study cohorts and will be separately evaluated for efficacy. All patients treated in the study will receive via a urinary catheter in the bladder, BCG plus ALT-803 or ALT-803 alone weekly for 6 consecutive weeks during the induction treatment period.

QUILT-2.005 is a phase 2b, randomized, two-cohort, open-label, multicenter study of intravesical ALT-803 plus BCG versus BCG alone, in BCG naïve patients with high-grade NMIBC. Patients will be enrolled into one of two study cohorts and randomized into two arms to be treated with either ALT-803 plus BCG or BCG alone. Cohort A will initially enroll 366 patients who have histologically confirmed CIS (with or without Ta/T1 papillary disease). Cohort B will initially enroll 230 patients who have histologically confirmed high-grade papillary Ta/T1 disease only. Cohorts A and B are two independent study cohorts and will be evaluated separately for efficacy.

PK sub-study: Blood samples to determine serum levels of ALT-803 will be collected on study day 1 prior to dosing, and at post-bladder voiding (+ 15 minutes), 24 (±2), 48 (±4), 72 (±4), 96 (±4) and 168 (±4) hours after dosing administered at study Week 1 and again at the same time points for study Week 6. Six subjects from either cohort A (either study) or cohort C (QUILT 3.032) and six subjects from cohort B (either study) will be sampled initially. Up to an additional 4 subjects for each cohort may also be sampled. Patients enrolled in QUILT 2.005 must have been randomized to receive ALT-803 plus BCG to be eligible for the PK sub-study.