Abstract 445P
Background
Neoadjuvant therapy (NAT) research based on PD-1 inhibitors has been widely carried out. However, there has been controversy over the cycle number and biomarkers.
Methods
A retrospective federated analysis of LA HNSCC patients (pts) who received NAT between March 2021 and April 2024 was conducted. Pts with AJCC 8th edition stage III-IVB (HPV-positive oropharyngeal : stage I-IV) and untreated LA HNSCC were selected. After enrollment, pts received 2 cycles of pembrolizumab/tislelizumab plus TP/PF regimen, and RT was used when CR was achieved on imaging. If PR, SD or PD was achieved, direct surgery or RT could be chosen, or 1-2 cycles of NAT could be received again before radical treatment. The primary endpoint was ORR. The targeted sample size was N=80, which provided 0.8 power based on Exact Test at One-Sided alpha level of 0.05. Data were analyzed by using IBM SPSS Statistics 29.
Results
A total of 82 pts were included. Baseline was shown in the table. The ORR was 84.1% after NAT. 50.9% (29/57) pts achieved pCR of primary lesion. no significant differents in ORR and pCR of Arm 1 and Arm 2. However, the T3-4 in the Arm 1 was significantly lower than Arm 2 (p=0.037). In T3-4 pts, pCR in Arm 1 was lower than Arm 2 (HR=0.76, 95%CI: 0.13-4.5, p=0.763). In addition, pCR of CPS ≥ 20 was significantly higher than that of CPS < 20 (66.7% vs 34.6%, HR=3.73, 95%CI: 1.0-13.4, p=0.044). Median follow-up time was 7 months, no pts disease progression. The laryngeal function preservation rate was 98.3% at 6 month. The TRAEs incidence rate was 72%, the most common Grade 3-4 TRAEs were myelosuppression (6.1%). Table: 445P
| Disease characteristics | N (%) | |
| Age (median, range) | 59 yrs (23-76) | |
| Gender | Male | 81 (98.8) |
| Primary tumor location | oropharyngeal | 22 (26.8) |
| HPV-postive (tested=21) | 13 (61.9) | |
| laryngeal | 10 (12.2) | |
| hypopharynx | 48 (58.5) | |
| nasal cavity and sinuses | 2 (2.4) | |
| Staging | I | 4 (4.9) |
| II | 10 (12.2) | |
| III | 21 (25.6) | |
| IV | 47 (57.3) | |
| CPS (tested=73) | ≥20 | 35 (48.0) |
| 1-19 | 36 (49.3) | |
| <1 | 2 (2.7) | |
| NAT cycles (2-cycle: Arm1; 3/4-cycle: Arm 2) | 2 | 37 (45.1) |
| 3 | 41 (50) | |
| 4 | 4 (4.8) | |
| Pathology acquisition method | Surgery | 49 (86.0) |
| Biopsy | 8 (14.0) | |
| PD-1 inhibitors | Pembrolizumab | 62 (75.6) |
| Chemotherapy | TP regimen | 77 (93.9) |
Conclusions
CPS is still an important biomarker in neoadjuvant immunotherapy for LA HNSCC. In addition, increasing the number of cycles may be beneficial for T3-4 pts. Prospective clinical studies (NCT06100497) are currently underway to further explore the efficacy and safety of PD-1 inhibitors combined with chemotherapy.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.