Can TTMV clearance predict recurrence in HPV HNSCC?

Abstract

6066 Background: Patients with locally advanced (LA) HPV HNSCC are treated with various types of induction chemotherapy (IC) followed by standard (sd) or reduced (rd) chemoradiation (CRT). Tumor tissue-modified viral HPV DNA (TTMV) pairs with PET-CT in predicting an early detection of treatment failure in HPV-related HNSCC. Mid-treatment TTMV assessment in HPV-related HNSCC can help identify patients who are eligible to receive a lower dose of IC and/or CRT or those who may require close follow-up. Methods: Patients with LA HPV+ HNSCC with high-risk features (radiographic ECE, T4 primary, >N2c) and <20 pack-year (py) smoking history were treated with IC followed by rdCRT (56 Gy); sdCRT (70 Gy) was used in non-responders. 16/23 received IC with TPF, 1/23 TP, and 6/23 TP-PD1, and all patients received carboplatin weekly with their CRT. Regeneron trial patients who received TP-Cemiplimab (PD1) IC followed by sdCRT are also continuing adjuvant Cemiplimab alone for 6 months (NCT05376553). PET-CT-confirmed residual, recurrent, or metastatic diseases were defined as treatment failures; TTMV + patients only if PET-CT confirmed. Results: 23 subjects treated with IC followed by CRT between 2/4/21-1/26/24, who had pre- and post-treatment TTMV were included in our analysis. The median pre-IC TTMV was 8082 (27 – 90770). The median follow-up time from treatment start was 21 months. 9/23 patients had full clearance TTMV after 1 cycle of IC defined as rapid responders (RR). 11/23 patients still had positive TTMV after 1st cycle of IC were defined as slow responders (SR). 1 patient had no TTMV done after 1 cycle of IC but was elevated after 2nd IC; he was defined as SR. 2 patients had a positive pre-IC TTMV, but no TTMV was drawn during IC to see if RR. 1 of 2 patients was TTMV negative prior to CRT, and 2/2 had a 1st post IC negative TTMV done 1 week after CRT started. They were both included in the analysis but defined as unknown response status. TTMV testing was done for all 23 subjects after CRT; all were negative. All subjects have TTMV testing done during their surveillance visits. Among 9/23 RR, none developed a failure. Among 12/23 SR, 3 patients developed a failure: 1/3 was TTMV+ but PET-, being followed with TTMV and PET-CT; and 2/3 were confirmed failures, TTMV+ and PET+; 1 locoregional, 1 metastatic. 2 patients were not known to be a SR or RR and had no recurrence. Among 23 patients, NPV of TTMV to detect failure was 100%, but PPV was 96% (1/23). Conclusions: IC followed in rapid clearance of TTMV in 39% of patients, and all remained disease-free. 3/11 (27%) with persistently elevated TTMV after cycle 1 relapsed as of this time point. This small study was not large enough to be practice-changing. However, this is significantly hypothesis-generating and should be tested in a larger trial to help identify patients for de-escalation (RR) or closer surveillance (SR).