Objective : This study evaluates the safety/efficacy of sabatolimab plus spartalizumab in patients with melanoma or non-small cell lung cancer (NSCLC).

Design, setting and participants : This is a phase 1–1b/2, open-label, multinational, multicentre study of patients with advanced/metastatic melanoma or NSCLC with ≥1 measurable lesion.

Interventions : Patients were given sabatolimab 800 mg every 4 weeks plus spartalizumab 400 mg every 4 weeks until unacceptable toxicity, disease progression and/or treatment discontinuation.

Outcome measures : The phase 2 primary outcome measure was overall response rate and secondary objectives included evaluation of the safety, tolerability, efficacy and pharmacokinetics of sabatolimab in combination with spartalizumab.

Results : 33 patients (melanoma n=16, NSCLC n=17) received sabatolimab plus spartalizumab. 31 (94%) experienced ≥1 adverse event (AE); 15 (46%) experienced grade 3/4 events. The most frequent grade ≥3 AEs for NSCLC were anaemia, dyspnoea and pneumonia (each n=2, 12%); for patients with melanoma, the most frequent grade ≥3 AEs were physical health deterioration, hypokalaemia, hypophosphataemia, pathological fracture and tumour invasion (each n=1; 6%). One (3%) patient discontinued treatment due to AE. Stable disease was seen in three patients with melanoma (19%) and six patients with NSCLC (35%). Median progression-free survival was 1.8 (90% CI 1.7 to 1.9) and 1.7 (90% CI 1.1 to 3.4) months for patients with melanoma and NSCLC, respectively. Patients with stable disease had higher expression levels of CD8, LAG3, programmed death-ligand 1 and anti-T-cell immunoglobulin and mucin-domain containing-3 at baseline. The pharmacokinetics profile of sabatolimab was consistent with the phase 1 study.

Conclusions : Sabatolimab plus spartalizumab was well tolerated in patients with advanced/metastatic melanoma or NSCLC who had progressed following antiprogrammed death-1/antiprogrammed death-ligand 1 treatment. Limited antitumour activity was observed. The tolerability of sabatolimab administration supports the potential to explore treatment with sabatolimab in various combination regimens and across a spectrum of tumour types.

Trial registration number : NCT02608268 .