P57.07 The Scottish Immunotherapy Prognostic Score (SIPS) Predicts Response to First-Line Pembrolizumab for Metastatic Non-Small Cell Lung Cancer

Abstract

The anti-PD1 immune checkpoint inhibitor pembrolizumab is an established first-line treatment option for patients with metastatic non-small cell lung cancer (NSCLC) with PDL1 expression ≥50%. Durable responses may be seen in a subset of patients; however, many derive little clinical benefit from treatment. Biomarkers that predict response are an unmet clinical need. Biomarkers of the systemic inflammatory response predict survival in NSCLC. We evaluated the prognostic significance of these biomarkers in first-line pembrolizumab for metastatic NSCLC. All patients treated with pembrolizumab monotherapy for metastatic NSCLC with PDL1 expression ≥50% at a regional cancer centre in Scotland were identified from the electronic patient record. Key inflammatory biomarkers (white cell count, neutrophil count, neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, albumin, prognostic nutritional index) within 14 days of starting treatment were recorded. The relationship between these and progression-free survival (PFS) and overall survival (OS) were examined using Cox-regression and Kaplan-Meier methods. Data were available for 167 patients with median age 69 and 89 (53%) female. Median PFS was 8.7 months and median OS was 15.2 months. On multivariate analysis albumin and neutrophil count were each independently associated with PFS (both p<0.001) and OS (both p<0.001). Given the consistent, highly significant relationship between albumin and neutrophil count with both PFS and OS a simple cumulative score combining these biomarkers was explored. The Scottish Immunotherapy Prognostic Score (SIPS) assigned 1 point each for albumin <35g/L and neutrophil >7.5X109/L to give a 3-tier score: 0 (low-risk), 1 (moderate-risk), 2 (high-risk). SIPS was predictive of PFS (HR2.45 95%CI 1.89-3.18 (p<0.001)) and OS (HR2.82 (95%CI 2.12-3.75 (p<0.001)). It stratified PFS from 1.7 months (SIPS:2), 9.4 months (SIPS:1) to 22.1months (SIPS:0) (p<0.001) and OS from 3.1 months (SIPS:2), 16.7 months (SIPS:1) to “not reached” (SIPS:0) (p<0.001) (Figure 1). The relative risk of death before 6 months was 2.65 (95% CI 1.78-3.80) in patients with SIPS 2 compared to those with SIPS 0-1 (p<0.001). SIPS, a cumulative score of albumin and neutrophil count, predicts survival in patients with NSCLC receiving first-line pembrolizumab monotherapy. Unlike many proposed prognostic scores in this setting, SIPS uses only routinely collected pre-treatment test results and provides a 3-teir categorical score. This simple score stratifies survival across a clinically meaningful time period and may assist treatment decision making. Additional work is needed to define the risks and benefits of this approach. We advocate evaluation of the prognostic utility of this biomarker of systemic inflammation in other immunotherapy treatment settings.