Bone-specific response according to MDA criteria predicts immunotherapy efficacy among advanced non-small cell lung cancer (NSCLC) patients

Purpose: The presence of bone metastasis at baseline has been associated with dismal prognosis under immunotherapy in advanced non-small cell lung cancer (NSCLC). Response Evaluation Criteria in Solid Tumors (RECIST) criteria may be limited for bone-specific response evaluation. Whether their assessment through MD Anderson (MDA) criteria predict immunotherapy efficacy is unknown. Materials and methods: We conducted a single-center retrospective study to assess the use of MDA criteria in evaluating bone metastasis in NSCLC treated with immunotherapy. Radiological imaging were reviewed to classify bone lesions as osteolytic, osteoblastic, or mixed. Bone response to treatment data was classified according to MDA criteria. Results: 222 patients received single-agent immunotherapy. The presence of bone metastasis increased the risk of death both in the univariate (HR: 1.46, 95% CI, 1.05–2.03, p = 0.024) and in the multivariate model (HR: 1.61, 95% CI, 1.10–2.36, p = 0.015). According to MDA criteria, 57.3% of patients had progressive disease as best response, 29.5% stable disease, 11.4% partial response and 1.6% complete response. Bone-specific objective response was associated with a significantly increased median overall survival (11.3 vs. 3.1 months, p = 0.027) and longer median progression-free survival (6 vs. 2.1 months, p = 0.056). The median time to bone failure (TBF) was 2.4 months (IQR, 1.67–3.0). In 25.7% of cases, TBF was shorter than progression-free survival according to RECIST 1.1 criteria. TBF was positively correlated with overall survival (HR = 0.73, p = 0.00019). Conclusions: MDA criteria represent a reliable tool in assessing bone-specific response, offering a more accurate evaluation with the aim to earlier predict survival outcomes or treatment failure compared to RECIST criteria for advanced NSCLC patients receiving immunotherapy.