Among patients with EGFR-mutant advanced NSCLC, those who also carry high PD-L1 expression represent a stubborn clinical problem: they respond worse to osimertinib than low-PD-L1 expressers, yet the antibody-based checkpoint inhibitors that target PD-L1 have historically been excluded from or underperformed in EGFR-mutant populations. That gap is exactly where Abbisko Therapeutics and AstraZeneca are now placing their bet. The two companies have cleared an IND with China’s NMPA, as of May 20, 2026, to begin a multicenter, open-label Phase I/II study combining Abbisko’s oral PD-L1 inhibitor lumipodlin (ABSK043) with TAGRISSO (osimertinib), which generated $7.25 billion in lung cancer revenue in fiscal year 2025 alone.
The scientific rationale is specific. FLAURA subgroup data showed that PD-L1 expression status did not substantially alter osimertinib’s efficacy advantage over earlier-generation comparators, which sounds reassuring until you consider the absolute outcome numbers in high-expressers: they still do worse. Lumipodlin’s proposed mechanism offers a different angle than monoclonal antibodies. Rather than blocking PD-L1 from outside the cell, the small molecule binds the receptor and drives its internalization, removing it from the tumor cell surface entirely. Preclinical data suggest anti-tumor activity comparable to approved PD-L1 antibodies, and the drug is already in a Phase I trial for advanced solid tumors in Australia and China. Oral bioavailability matters here because it enables a fully oral regimen when paired with osimertinib, a logistical and tolerability consideration that is genuinely relevant in a patient population already managing a chronic daily pill burden.
AstraZeneca’s involvement is not passive. Both companies share trial responsibilities, and AstraZeneca is supplying TAGRISSO for the combination. For AstraZeneca, this is a low-capital way to probe whether osimertinib’s ceiling in PD-L1-high patients can be raised without introducing IV infusion schedules or the pulmonary toxicity concerns that have complicated prior EGFR-TKI plus checkpoint inhibitor combinations. For Abbisko, the partnership provides clinical infrastructure and a globally recognized backbone agent to validate lumipodlin’s mechanism in a precisely defined biomarker-selected cohort.
The Phase I/II design means the first inflection point is a safety readout in the dose-escalation portion. Immune-related adverse events and potential pharmacokinetic interactions between the oral small molecule and osimertinib are the immediate unknowns. Watch for the Phase I safety and preliminary efficacy data from this combination specifically in EGFR-mutant, PD-L1-positive patients: if lumipodlin can demonstrate tolerability at therapeutically active doses alongside full-dose osimertinib, the design argument for a registrational trial becomes considerably harder to dismiss.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
