No third-generation EGFR-TKI is currently approved for NSCLC brain metastases, and the potential impact of ESAONA data on this gap remains to be defined. Asandeutertinib (TY-9591), a novel third-generation EGFR-TKI, has already shown acceptable safety and encouraging efficacy in earlier Phase I and single-arm Phase II studies, but its comparative advantage over existing agents is still unclear.

To further evaluate this, the company initiated the open-label, multicenter, randomized Phase II (ESAONA) trial. At ASCO, TYK Medicines presented early results comparing asandeutertinib with osimertinib (TAGRISSO) in EGFR-mutated NSCLC patients with brain metastases. These interim findings, featured among key late-breaking abstracts, indicate improved efficacy with asandeutertinib, suggesting a potential new treatment option for this difficult-to-treat population. The detailed results are described below:

Efficacy:

• Intracranial ORR:  95.5% vs. 79.6% with osimertinib)

• Investigator-assessed ORR was 92.8% and 77.9%, respectively 

• Intracranial PFS: Not reached; but was 17.51 months with osimertinib

• Data for the key secondary endpoint of overall survival (OS) remains immature

• Strong CNS activity with durable brain lesion control

Safety:

• Treatment-related adverse events occurred in 99.1% of patients receiving asandeutertinib and 95.6% receiving osimertinib. 

• Treatment-related serious adverse events were reported in 10.8% and 7.1% of patients, respectively. 

• No new safety concerns were identified.

KOL insights

“The efficacy and safety results demonstrate that asandeutertinib can deliver prominent clinical value and advantages in achieving intracranial lesion remission and disease control with a favorable trend of longer and superior survival as well as improved quality of life.” –Expert Opinion

“The current treatment options for patients with NSCLC and brain metastases show limited efficacy, adding that the lack of standardized treatment regimens and targeted therapies for these patients has created “a substantial unmet clinical need.”–Expert Opinion

Conclusion: 

EGFR mutations are key drivers of tumor progression and treatment resistance in NSCLC. While first- and second-generation EGFR-TKIs significantly improved progression-free survival compared with chemotherapy, resistance still emerges in ~50–80% of patients after a median of ~11 months. NSCLC has evolved into a biomarker-driven disease, with EGFR representing a major commercial segment led by osimertinib (TAGRISSO), the current dominant EGFR-TKI. Despite these advances, brain metastases remain a major unmet challenge, occurring in ~15% of patients at diagnosis and up to ~65% during disease progression, with currently available therapies offering limited intracranial efficacy.

Asandeutertinib (TY-9591), a novel third-generation EGFR-TKI, has demonstrated acceptable safety and encouraging efficacy in Phase I and single-arm Phase II studies, although its benefit over existing therapies remained uncertain. To address this, the randomized, open-label Phase II ESAONA trial was conducted—the first head-to-head comparison of asandeutertinib versus osimertinib in EGFR-mutated NSCLC with brain metastases, with dual primary endpoints of intracranial ORR and iPFS.

At ASCO 2026, asandeutertinib demonstrated improved intracranial response and survival versus osimertinib with manageable safety and no new safety signals, suggesting a potential new treatment option for this high-unmet-need population.