Second-Line Regimen Choice and Re-Biopsy Realities in EGFR-Mutant NSCLC After Osimertinib

Dr. Doroshow asks how Dr. Patel weighs COMPEL (osimertinib continuation with chemotherapy; progression-free survival [PFS] 8.4 vs. 4.4 months) against MARIPOSA-2 (amivantamab plus chemotherapy; PFS 6.3 vs. 4.2 months) for patients progressing on frontline osimertinib, and whether a prolonged chemotherapy-free interval changes willingness to rechallenge with platinum.

Dr. Patel notes both studies come from the FLAURA-1 era. He frames the choice as carrying forward the reasoning that drove the original osimertinib selection. Borderline renal function may make MARIPOSA-2 with chemotherapy inappropriate; cutaneous toxicity concerns favor chemotherapy-based options; geographic access points to infusion frequency. He references the third arm of MARIPOSA-2 — the quadruplet of chemotherapy, amivantamab, and lazertinib — as a learning that EGFR pressure from amivantamab alone is sufficient for CNS protection.

Dr. Doroshow shares that her frontline single-agent osimertinib patients tend to have borderline performance status, prompting creative second-line approaches. She has had prolonged disease control with dose-reduced single-agent pemetrexed added to osimertinib.

The discussion turns to re-biopsy practice. Dr. Patel says liquid biopsy is close to universal in his practice. For tissue biopsies, he selectively pushes patients with rapid unexpected progression or baseline TP53/RB1 mutations. He estimates tissue biopsy is feasible in about a third of patients but is the only reliable way to detect small cell transformation. Dr. Doroshow reinforces liquid biopsy is not the gold standard because fusions, copy number, and tumor mutational burden data may not match tissue.

In the next episode, "MET-directed resistance: testing, treatment selection, and toxicity management,” Dr. Doroshow transitions to the MET resistance landscape and asks Dr. Patel to walk through testing, treatment options, and adverse event management.