HB200 (HPV16 E6/E7 viral immunotherapy) + carbo/pac drives 88% deep responses and enables de-escalation in HPV16+ OPSCC

HB200 is an HPV16-directed arenavirus-based therapeutic vaccine regimen (HB201 and HB202 vectors encoding a non-oncogenic HPV16 E6/E7 fusion) given neoadjuvantly with carboplatin/paclitaxel in an investigator-initiated Phase I/II trial in previously untreated, non-metastatic HPV16+ oropharyngeal SCC with higher-risk features (N1-3 or T3-4; smokers allowed; n=35; NCT05108870). The primary endpoint deep response rate (≥50% radiographic shrinkage) was 87.9% (95% CI, 71.8-96.6), and 86% of patients received de-escalated definitive therapy (TORS alone for select T1-2 lateralized primaries with ≥50% shrinkage; otherwise response/risk-adapted RT 50-70Gy ± cisplatin); at median 23 months follow-up, 2-year PFS was 86% with OS 100%—numerically in the same ballpark as other de-intensification paradigms in good-risk HPV+ OPSCC (e.g., NRG-HN002 reported 2-year PFS 86% with 60 Gy + cisplatin, while ECOG-ACRIN E3311 reported 2-year PFS ~95% after TOS with risk-adapted adjuvant therapy). Toxicity during neoadjuvant HB200/chemo was dominated by expected chemo-like AEs (fatigue 97%, nausea 91%, fever 76%); post-treatment detectable ctHPV-DNA was significantly associated with recurrence (p<0.01), consistent with broader literature supporting ctHPV-DNA as a high-specificity recurrence signal in HPV+ OPSCC surveillance.