Vauchier C, Pluvy J, Theou-Anton N, et al. - A prolonged response to anti-programmed cell death protein (PD-1) therapy was seen in a NSCLC (non-small-cell lung cancer) patient with high microsatellite instability and POLE (polymerase proofreading) mutation and with inaugural poor general condition.

• The patient’s performance status (PS) improved markedly from PS 3 before ICI (immune checkpoint inhibitors) administration to PS 1 upon ICI therapy.

• Scarce data exist on ICI’s safety and efficacy in poor PS NSCLC cases.

• Although mismatch repair deficiency and mutations in POLE are uncommon in NSCLC, they might be predictive of response to PD1-blockade.

• Such biomarkers could offer a better selection of poor PS patients for whom ICI might be beneficial.