Lung cancer is the leading cause of cancer deaths worldwide (18.0% of the total cancer deaths). Among them, Non-small cell lung cancer (NSCLC) accounts for approximately 84% of all lung cancers. Out of the 220,000 people diagnosed with NSCLC in the US each year, about one-third of them are in stage 3, i.e., when cancer has spread to nearby lymph nodes or other parts of the body near the lungs.

In February 2018, the FDA approved AstraZeneca's Imfinzi for treating patients with unresectable stage 3 NSCLC, without disease progression after treatment with CRT after the PD-L1 inhibitor significantly improved PFS and OS in patients. This led to Imfinzi becoming the standard of care in that setting and also helped AstraZeneca dominate the stage 3 market.

At the 2021 ESMO Annual Meeting, EQRx and its partner CStone Pharmaceuticals announced positive Phase 3 trial results for a low-cost anti-PD-L1 monoclonal antibody, sugemalimab, in what could be considered a potential warning to Imfinzi. Interim analysis of trial results showed that as compared to placebo, sugemalimab demonstrated a statistically significant and clinically meaningful improvement in PFS with a well-tolerated safety profile in patients with locally advanced/unresectable Stage 3 NSCLC.