First-in-human study of FAZ053, an anti-programmed death-ligand 1 (anti-PD-L1) monoclonal antibody, alone and in combination with spartalizumab, in patients with advanced malignancies

Background: FAZ053 triggers an antitumor response by targeting programmed death-ligand 1 (PD-L1), thereby activating effector T cells and negatively regulating T cells. This study assessed the safety, tolerability, and preliminary efficacy of FAZ053 monotherapy and in combination with spartalizumab in patients with advanced solid tumors.

Methods: This phase I, multicenter, open-label study (NCT02936102) included dose escalation and dose expansion. The primary objectives were safety and tolerability; secondary objectives were pharmacokinetics, pharmacodynamics, and preliminary antitumor activity.

Results: Of the 154 patients treated, 49 (52.7%) patients receiving FAZ053 monotherapy experienced at least one treatment-related adverse event (TRAE), of whom 6 (6.5%) experienced grade ≥3 TRAEs; 35 patients (57.4%) receiving combination therapy experienced TRAEs, of whom 3 (4.9%) experienced grade ≥3 TRAEs. One patient who received FAZ053 1600 mg every 6 weeks (Q6W) and one who received FAZ053 20 mg every 3 weeks (Q3W) with spartalizumab 300 mg Q3W experienced dose-limiting toxicities of grade 4 creatinine increase and grade 3 liver function test increased, respectively. The median duration of exposure was 105 days for monotherapy and 85 days for combination therapy. During dose escalation, response was observed in 3 (5.1%) and 3 (4.9%) patients receiving FAZ053 monotherapy and combination therapy, respectively. In dose expansion, response was observed in 2 (50%) patients with advanced alveolar soft part sarcoma (ASPS) and 3 (30%) patients with advanced chordoma receiving FAZ053 monotherapy. FAZ053 demonstrated a dose-proportional pharmacokinetic profile with a terminal half-life of 20.6 days at 1200 mg Q3W. Biomarker analysis showed increased immune gene expression following FAZ053 treatment. The recommended dose for expansion was 1200 mg Q3W.

Conclusion: FAZ053 monotherapy was well tolerated and effective in maintaining disease control in various tumors including ASPS and chordoma. The anticipated synergistic effect of combined programmed cell death protein 1 (PD-1) and PD-L1 inhibition was not observed. These findings contribute to the growing evidence that rare, phenotypically 'immune cold' sarcomas, such as ASPS and chordoma, can become responsive to immune checkpoint inhibitors.

FAZ053; PD-L1; advanced alveolar soft part sarcoma; chordoma; spartalizumab.