SAFFRON-301: a randomised phase III study of sitravatinib in combination with tislelizumab in patients with locally advanced or metastatic non-small cell lung cancer.

[BACKGROUND] Many patients with non-small cell lung cancer (NSCLC) have tumours that are either refractory or develop resistance following an initial response to anti-programmed cell death protein (ligand)-1 (PD-(L)1)-based treatment, resulting in limited treatment options. SAFFRON-301 evaluated whether combining the multikinase inhibitor, sitravatinib, with the anti-PD-1 antibody, tislelizumab, may overcome resistance to anti-PD-(L)1 therapy.

[METHODS] SAFFRON-301 (NCT04921358) was an open-label, randomised, phase III trial enrolling patients with unresectable locally advanced/metastatic NSCLC, who had disease progression on or after platinum-based chemotherapy and anti-PD-(L)1 antibodies. No more than two lines of prior systemic therapy were allowed. Patients were randomised 1:1 to receive sitravatinib 100 mg orally once daily plus tislelizumab 200 mg intravenously once every 3 weeks or docetaxel 75 mg/m intravenously every 3 weeks. Dual primary endpoints were overall survival (OS) and Independent Review Committee (IRC)-assessed progression-free survival (PFS).

[RESULTS] Overall, 377 patients were enrolled and randomised to receive sitravatinib plus tislelizumab (n=187) or docetaxel (n=190); 51.2% had squamous histology and 36.6% had PD-L1 expression in ≥1% of tumour cells. At a median follow-up of 11.7 (sitravatinib plus tislelizumab) and 11.4 months (docetaxel), median OS was similar (11.5 (95% CI 9.4 to 14.6) vs 11.4 (9.9 to 15.0) months, respectively; HR, 1.02 (95% CI 0.75 to 1.39)) between treatment arms. IRC-assessed median PFS was numerically longer with sitravatinib plus tislelizumab (4.4 (95% CI 4.0 to 5.7) months) vs docetaxel (2.9 (95% CI 2.6 to 4.2) months); HR, 0.82 (95% CI 0.62 to 1.07). IRC-assessed overall response rate was 12.3% with sitravatinib plus tislelizumab vs 12.6% with docetaxel. The most commonly reported treatment-emergent adverse events grade ≥3 in sitravatinib plus tislelizumab arm were hypertension (13.4%), pneumonia (9.1%), palmar-plantar erythrodysesthesia syndrome (6.5%) vs white blood cell count decreased (29.4%), neutrophil count decreased (28.8%), pneumonia (8.5%) and neutropenia (7.3%) in docetaxel arm. Grade 5 haemoptysis occurred in 3 (1.6%) patients with sitravatinib plus tislelizumab. The study was terminated due to an unfavourable risk-benefit analysis.

[CONCLUSIONS] The SAFFRON-301 study was terminated early due to unfavourable risk-benefit assessment in the investigational arm. Due to immature survival data, efficacy results should be interpreted with caution.

[TRIAL REGISTRATION NUMBER] NCT04921358.