Abstract
Abstract only 80 Background: Introducing amino acid sequence changes in highly expressed self-antigens for androgen sensitive prostate cancer pts might be sufficient to break tolerance, thus a DNA vaccine was developed using SynCon PSA and PSMA (INO-5150) that share 96.8 and 91.6% sequence identities to these native antigens, respectively. Administration of these antigens to prostate cancer pts along with plasmid encoded adjuvant IL-12 (INO-9012) via electroporation (EP) using the CELLECTRA5P device is postulated to break tolerance, resulting in an antigen-specific immune response which could lead to stabilization of disease progression. Methods: This Phase I, open-label, multicenter study included prostate cancer pts post-definitive therapy with a rising PSA ≥ 1.0 ng/ml after surgery, or ≥ 2.0 ng/ml above nadir after RT and PSA doubling time > 3 months, testosterone > 150 ng/dL and no evidence of metastasis within 12 months. INO-5150 with or without INO-9012 was administered IM followed by EP in 4 arms: low (2 mg) or high dose (8.5 mg) INO-5150 alone or with 1 mg INO-9012 on Day 0 and at week 3, 12, and 24 in 60 planned pts (15 pts/arm). DLT assessments were performed after dosing of the first 3 pts of each arm at Week 4. Results: Enrollment is complete in all 4 arms and at data cut-off (10Oct16), 62 enrolled pts received at least one, 60 pts received 3 and about half, 28 pts (10 in arm A, 8 in B, 7 in C, and 3 in D) received all 4 vaccinations. Safety: there were no DLTs noted. Four pts had five Grade 3 SAEs noted as pre-syncope, cardiac disorder, hospitalization for fall, ALT and AST elevation. No Grade 4-5 AEs were noted. Grade 1-3 treatment-emergent AEs occurred in 50 (81%) pts: 12 (75%) in arm A, 13 (87%) B, 13 (87%) C, and 12 (75%) in D. The most common AEs were injection site pain (24/39%), erythema (13/21%), swelling (12/19%), bruising (10/16%), hyperglycemia (8/13%) and fatigue (6/10%), all Grade 1-2. Assessments of immunological response, PSA kinetics and correlation with clinical outcome are ongoing and will be presented. Conclusions: INO-5150 (+) or (-) INO-9012 is generally safe and well-tolerable at all 4 dose levels in a biochemically relapsed prostate cancer patient population. Clinical trial information: NCT02514213.