Neoadjuvant Finotonlimab Plus TP Regimen in Locally Advanced INI-1-Deficient Sinonasal Carcinoma

This phase 2 study is designed to evaluate the efficacy and safety of neoadjuvant finotonlimab combined with TP chemotherapy in patients with locally advanced INI-1 (SMARCB1)-deficient sinonasal carcinoma. INI-1 deficiency defines a rare, aggressive subtype of sinonasal carcinoma with a high propensity for skull base invasion and limited response to conventional induction chemotherapy. The study hypothesis is that adding PD-1 blockade to standard TP chemotherapy will increase the preoperative objective response rate, facilitate tumor downstaging, improve R0 resection, and potentially reduce surgical morbidity while preserving organ function.

Approximately 20 eligible participants will be enrolled across multiple centers. All participants will receive 2 cycles of neoadjuvant therapy every 21 days: finotonlimab 200 mg intravenously on day 1, followed by paclitaxel 135-175 mg/m² on day 1 and cisplatin 70-75 mg/m² on days 1-3, with standard premedication, hydration, and antiemetic support. After 2 cycles, tumor response will be assessed by contrast-enhanced MRI of the skull base and chest CT, with independent blinded central review using RECIST v1.1. Participants with complete response, partial response, or stable disease will proceed to definitive surgery aiming for R0 resection, followed by postoperative intensity-modulated radiotherapy (60-66 Gy in 30-33 fractions) after adequate wound healing. Participants with progressive disease will discontinue the study regimen and receive salvage therapy as determined by the multidisciplinary team.

The primary endpoint is objective response rate after 2 cycles of neoadjuvant therapy, assessed by blinded independent central review. Secondary assessments include disease control rate, R0 resection rate, major pathological response, pathological complete response, disease-free survival, overall survival, safety and tolerability according to CTCAE v5.0, surgery- and radiotherapy-related complications, quality of life using EORTC QLQ-C30 and QLQ-H\&N35, and organ preservation rate. Exploratory analyses will evaluate the association of PD-L1 CPS, Ki-67, TP53 mutation status, and serial circulating tumor DNA dynamics with treatment response and recurrence risk, and will explore baseline clinical features such as T stage and cranial nerve involvement as potential predictors of benefit.

This study is expected to provide the first prospective multicenter evidence for neoadjuvant PD-1 blockade combined with TP chemotherapy in this ultra-rare sinonasal malignancy. If positive, the results may support a new preoperative treatment paradigm aimed at improving resectability and functional outcomes, and will inform future larger studies.

All participants are enrolled in this single experimental arm and receive the same study-specified treatment sequence. Participants first receive 2 cycles of neoadjuvant therapy, with each cycle lasting 21 days: finotonlimab 200 mg by intravenous infusion on day 1; paclitaxel 135-175 mg/m² by intravenous infusion on day 1; and cisplatin 70-75 mg/m² by intravenous infusion on days 1-3. Standard premedication, hydration, antiemetic prophylaxis, and supportive care are given according to institutional practice. After 2 cycles, tumor response is assessed by contrast-enhanced MRI of the skull base and chest CT with blinded independent central review using RECIST v1.1. Participants with complete response, partial response, or stable disease then undergo definitive surgery aiming for R0 resection. Postoperative intensity-modulated radiotherapy (IMRT) of 60-66 Gy in 30-33 fractions is planned to start 4-6 weeks after surgery, once wound healing and general condition permit. Participants with

Drug: Finotonlimab · Drug: Paclitaxel · Drug: Cisplatin

Finotonlimab is an anti-PD-1 monoclonal antibody administered as part of neoadjuvant therapy. It is given intravenously at a fixed dose of 200 mg on day 1 of each 21-day cycle, for a total of 2 cycles. It is infused before paclitaxel and cisplatin on the same day. This is the experimental immunotherapy component of the study regimen.

Paclitaxel is a standard cytotoxic chemotherapy agent administered as part of the neoadjuvant TP regimen. It is given by intravenous infusion over 3 hours on day 1 of each 21-day cycle, at a dose of 135-175 mg/m², for a total of 2 cycles. Standard premedication (dexamethasone, diphenhydramine, and cimetidine or an equivalent H2 blocker) is given before infusion to prevent hypersensitivity reactions. Paclitaxel is administered after finotonlimab and before cisplatin.

Cisplatin is a standard platinum-based chemotherapy agent administered as part of the neoadjuvant TP regimen. It is given by intravenous infusion at a dose of 70-75 mg/m² on days 1-3 of each 21-day cycle, with the total dose for the cycle divided across the three days, for a total of 2 cycles. It is administered after paclitaxel on day 1. Standard hydration, diuresis, and electrolyte supplementation (potassium and magnesium) are provided. This divided-day schedule is used to reduce acute nephrotoxicity and severe emesis associated with single high-dose cisplatin.

Time frame: After completion of 2 cycles of neoadjuvant therapy (each cycle is 21 days; response assessment performed approximately 3 weeks after the last dose of cycle 2)

Objective response rate (ORR) is defined as the proportion of participants who achieve a complete response (CR) or partial response (PR) after 2 cycles of neoadjuvant finotonlimab plus TP chemotherapy. Tumor response is assessed by contrast-enhanced MRI of the skull base and chest CT, and evaluated by a blinded independent central review (BICR) according to RECIST v1.1. ORR is calculated as (CR + PR) divided by the number of participants in the full analysis set (all enrolled participants who signed informed consent and received at least 1 dose of study treatment). The 95% confidence interval will be estimated using the Clopper-Pearson exact method.

Time frame: Approximately 9 weeks after the first dose of neoadjuvant therapy (after 2 cycles of 21 days each), consistent with the primary ORR assessment time point.

DCR is defined as the proportion of participants who achieve complete response (CR), partial response (PR), or stable disease (SD) after 2 cycles of neoadjuvant finotonlimab plus TP chemotherapy, assessed by blinded independent central review (BICR) using RECIST v1.1. DCR is calculated as (CR + PR + SD) divided by the number of evaluable participants.

Time frame: At the time of definitive surgery (after completion of 2 cycles of neoadjuvant therapy)

R0 resection rate is defined as the proportion of participants who undergo surgery and achieve microscopically negative surgical margins (R0), as confirmed by central pathology review. The denominator is all participants who undergo definitive surgery.

Time frame: From the date of surgery until the date of first documented recurrence, metastasis, or death from any cause, assessed up to 3 years after surgery.

DFS is defined as the time from the date of surgery to the date of local recurrence, distant metastasis, or death from any cause, whichever occurs first. DFS will be estimated using the Kaplan-Meier method.

Time frame: From the date of enrollment until the date of death from any cause, assessed up to 3 years after enrollment.

OS is defined as the time from enrollment (or randomization, if applicable) to the date of death from any cause. Participants alive at the last follow-up will be censored at that date. OS will be estimated using the Kaplan-Meier method.

Time frame: At the time of definitive surgery (after completion of 2 cycles of neoadjuvant therapy).

MPR is defined as the proportion of participants whose surgically resected specimens contain ≤10% viable tumor cells, as assessed by central pathology review. The denominator is all participants who undergo definitive surgery and have evaluable pathological specimens.

Time frame: At the time of definitive surgery (after completion of 2 cycles of neoadjuvant therapy).

pCR is defined as the proportion of participants whose surgically resected specimens contain no viable tumor cells, as assessed by central pathology review. The denominator is all participants who undergo definitive surgery and have evaluable pathological specimens.

Time frame: From the first dose of neoadjuvant therapy until 30 days after the last dose of neoadjuvant therapy (approximately 3 months).

All adverse events (AEs), Grade ≥3 AEs, and serious adverse events (SAEs) occurring during neoadjuvant therapy will be recorded and graded according to CTCAE v5.0. The type, incidence, and outcome of each event will be summarized descriptively.

Time frame: From the date of surgery until 12 months after completion of postoperative radiotherapy.

The incidence of prespecified complications will be recorded, including cerebrospinal fluid leak, intracranial infection, cranial nerve injury, major hemorrhage, trismus, and radiation-induced brain injury. Complications will be documented from the surgical record and during the postoperative radiotherapy and follow-up periods

Time frame: Baseline, before surgery (after neoadjuvant therapy), after surgery, and every 6 months during follow-up, assessed up to 3 years after enrollment.

Quality of life will be assessed using the EORTC QLQ-C30 (Version 3.0) and the head and neck module QLQ-H\&N35. Scores for functional scales, symptom scales, and the global health status/QoL scale will be collected and the change from baseline will be summarized at each prespecified time point.

Time frame: At the time of definitive surgery (after completion of 2 cycles of neoadjuvant therapy).

Organ preservation rate is defined as the proportion of participants who undergo definitive surgery without orbital exenteration or extensive craniofacial/maxillary resection. Organ preservation status will be determined from the surgical record and multidisciplinary team assessment.

Neoadjuvant Finotonlimab Plus TP Regimen in Locally Advanced INI-1 (SMARCB1)-Deficient Sinonasal Carcinoma: A Prospective, Multicenter, Single-Arm Phase II Clinical Study