Rapid and objective CT scan prognostic scoring identifies metastatic patients with long-term clinical benefit on anti-PD-1/-L1 therapy

Drugs targeting programmed death receptor-1 (PD-1) and its ligand PD-L1 have shown activity in multiple malignancies. Considering their novel mechanism of action, whether traditional prognostic scores also apply to patients treated with these drugs is unknown. We investigated whether a baseline 3-point (pt) computed tomography (CT) scan (PS3-CT) score and a 7-pt prognostic (PS7) score allowed identifying long-term survivors on anti-PD-1/-L1 therapy.

We reviewed 251 consecutive patients enrolled in phase I trials evaluating anti-PD-1/-L1 agents between 26th December 2011 and 7th September 2015. PS3-CT was calculated using high tumour burden (TB1D-RECIST > 9 cm), low skeletal muscle index (SMI < 53 cm(2) m(-2)) and non-pulmonary visceral metastases (NPVM) (1 pt each). PS7 was calculated by adding lower performance status, decreased serum albumin, increased serum lactate dehydrogenase and more than two distant metastases (1 pt each). Effect on overall survival (OS) of each parameter was tested using Kaplan-Meier and multivariable Cox analyses.

PS3-CT was a significant independent predictor of OS (hazard ratio [HR] = 1.39 [95% confidence interval {CI} = 1.07-1.81], p = 0.01) when compared to the Royal Marsden Hospital, Barbot and American Joint Committee on Cancer scores. High TB (n = 78), low SMI (n = 55) and NPVM (n = 146) were associated with poorer survival (p < 0.01). High TB and low SMI were independent predictors of OS (respective HR of death: 2.00 [95% CI = 1.38-2.88], p < 0.01 and 1.75 [95% CI = 1.15-2.66], p < 0.01). PS7 was a significant predictor of OS (HR = 1.40 [95% CI = 1.25-1.56], p < 0.01).

Objective and rapid-risk scoring based on three CT scan parameters allows identifying patients with prolonged OS on anti-PD-1/-L1 therapy, independently from conventional clinical-biological prognostic scores.