Stereotactic body radiation therapy with sequential immunochemotherapy as neoadjuvant therapy in resectable non-small cell lung cancer (SACTION-01 study).

8540 Background: Neoadjuvant PD-1 inhibitor plus chemotherapy increases pathological response for resectable non-small cell lung cancer (NSCLC) compared with chemotherapy alone. Previous phase II trial indicated that stereotactic body radiation therapy (SBRT) served as an immunomodulator and enhanced the effect of preoperative immuno-monotherapy. However, whether SBRT would further increase the efficacy of immunochemotherapy for NSCLC remains unknown. Methods: In this phase II trial, patients with resectable EGFR wild-type stage IIA to IIIB NSCLC were recruited to receive SBRT (24 Gy in 3 daily fractions) to the primary tumor followed by two cycles of PD-1 inhibitor tislelizumab (200 mg) plus platinum-based doublet chemotherapy (Q3W) before surgical resection. The primary endpoint was major pathological response (MPR) defined as no more than 10% of viable tumor cells in the specimen. Simon’s optimal two-stage design was used for conducting the trial. The null hypothesis was that the MPR rate is 0.30, and the alternative hypothesis was that the true MPR rate was 0.50. More than 4 MPRs were needed in stage 1 (n=15) to continue, and if there were 19 or more MPRs in 46 patients by the end of stage 2, the null hypothesis can be rejected. The design controls the type I error rate at 0.05 and yields the power of 0.80. (NCT05319574). Results: Between May 2022 and Jan 2023, 32 patients were enrolled with 31 (96.9%) male and 19 (59.4%) having squamous cell lung cancer. Twenty-six (81.3%) patients had stage IIIA/B disease. All patients received at least one cycle of immunochemotherapy; 23 of the 25 patients (92.0%) who completed treatment had undergone R0 resections, except for one patient who had disease progression and the other one that unable to tolerate surgery because of grade 4 neutropenia. Twenty-two patients underwent minimally invasive approaches and 3 of them (13.6%) converted to thoracotomy. The median percentage of the viable tumor was 0 (interquartile range: 0-4.0%). Twenty patients achieved MPR, which surpassed the prespecified required number to reject the null hypothesis, resulting in the MPR rate of 80.0% (20/25) in the intention-to-treat population, and 87.0% (20/23) in the per-protocol population. Pathological complete response (pCR) was found in 14 patients (56.0% in the intention-to-treat population and 60.9% in the per-protocol population). Nodal clearance status (pN0) was found in 20 of 23 cN1/2 cases (87.0%). Grade 3-4 adverse events related to neoadjuvant treatment included neutropenia (13.0%), anemia (4.3%), and pneumonia (4.3%). No 30-day or 90-day mortality was observed. Conclusions: Neoadjuvant SBRT followed by immunochemotherapy yields unprecedently high MPR and pCR rates in NSCLC without EGFR mutation. The trial will continue to recruit 14 more patients to reach a final sample size of 46 participants. Clinical trial information: NCT05319574 .