Dissociated responses (DR) are phenomena in which some tumors shrink, whereas others progress during treatment of patients with cancer. The purpose of the present study was to evaluate the frequency and prognosis of DR in non-small cell lung cancer (NSCLC) patients treated with anti-program cell death-1/ligand 1 (anti-PD-1/L1) inhibitors.
This retrospective study included NSCLC patients who received anti-PD-1/L1 inhibitor as second- or later-line treatment. We excluded patients without radiological evaluation, including brain imaging within 28 days prior to the treatment, and those without measurable lesions. We evaluated all measurable lesions in each organ. We defined DR as a disease with some shrinking lesions as well as growing or emerging new lesions in patients who showed progressive disease (PD), according to the RECIST 1.1 at the initial CT evaluation. Cases not classified as DR were defined as ‘true PD’. Overall survival was compared between patients with DR and those with true PD using Cox proportional hazards models.
The present study included 62 NSCLC patients aged 27–82 years (median: 65 years). DR and true PD were observed in 11 and 51 patients, respectively. Nivolumab, pembrolizumab, and atezolizumab were administered to 45, 7, and 10 patients, respectively. Median overall survival was significantly longer in patients with DR versus true PD (14.0 vs. 6.6 months; hazard ratio for death: 0.40; 95% confidence interval: 0.17–0.94).
The frequency of DR in NSCLC patients who showed PD to anti-PD-1/L1 was 17.7%. Patients with DR exhibited a relatively favorable prognosis.