TP53 Co-Mutation in EGFR-Mutated NSCLC: Clinical Significance and Impact on Frontline Therapy Choice

Dr. Riess highlights TP53 co-mutation as one of the most compelling high-risk subgroups in EGFR-mutated NSCLC, asking Dr. Fidler how TP53 co-mutation status influences frontline treatment selection. TP53 mutations, identified through routine next-generation sequencing (NGS) at diagnosis, represent a well-established adverse prognostic factor associated with significantly shorter PFS on TKI monotherapy, with median PFS approaching only 1 year on osimertinib alone in this population. The MARIPOSA subgroup analysis demonstrated a meaningful improvement in PFS with amivantamab-lazertinib over osimertinib in TP53 co-mutated patients (18.2 versus 12.9 months; hazard ratio 0.65). FLAURA2 also showed consistent OS benefit across TP53 subgroups.

Dr. Fidler identifies TP53 co-mutation as one of several high-risk features that reinforce her recommendation for frontline combination therapy, alongside CNS metastases and elevated circulating tumor DNA (ctDNA). She emphasizes that even in the absence of TP53 co-mutation, she routinely recommends combination therapy for eligible patients, making TP53 positivity a reinforcing rather than a solitary driver of that decision. She notes clinical concern about faster progression in this group, underscoring the importance of securing maximal disease control upfront.

Dr. Riess adds that TP53 co-mutations are particularly relevant in younger patients with EGFR-mutated NSCLC, where concurrent TP53 mutations are more frequently detected. He notes that patients who did not achieve ctDNA clearance by cycle 3 day 1 in MARIPOSA also showed dramatic PFS benefit from amivantamab-lazertinib versus osimertinib (hazard ratio 0.49), underscoring the value of molecular risk stratification in guiding frontline EGFR-mutated NSCLC treatment decisions.