1094P NeoRisk: Neoadjuvant immunotherapy (NeoIT) recurrence risk assessment tool

NeoIT with anti-PD-1 (PD1) is now a standard of care for patients (pts) with resectable stage IIIB–D melanoma. Although pathological response is predictive of recurrence, this variable alone cannot accurately identify those pts who will recur, particularly non-responders. We sought to build a recurrence risk assessment tool based on pts demographics, disease characteristics, pathological and imaging data.

Pts with resectable stage IIIB–D melanoma treated with PD1-based neoIT were included. Pts demographics, disease characteristics, blood parameters, pathological and imaging data at baseline (BL) and post-treatment (post-Tx), and clinical outcomes were analysed. A penalised multivariable logistic regression model was built to predict recurrence and a tool (NeoRisk) predicting the likelihood of recurrence for individual patients was generated.

164 pts who underwent surgery post PD1-based NeoIT and had at least 6 months of follow-up were included; training cohort (n=114; 16 recurrences, 14%) and validation cohort (n=50; 7 recurrences, 14%). After the analysis of >50 variables, the combination of 4 variables accurately predicted recurrence (training cohort, AUC=0.91; validation cohort, AUC=0.93): 1) % of viable tumour cells in the tumour bed post-Tx (AOR=2.55, p=0.0016); 2) density of tumour-infiltrating lymphocytes (TILs) post-Tx (absence, mild, moderate, marked; e.g. marked vs absence, OR=0.39, p=0.0115); 3) difference in the % of fibrosis from BL to post-Tx (OR=0.69, p=0.0531); and 4) % tumour change from BL by RECIST (OR=2.06, p=0.0043). NeoRisk can be used to predict recurrence for individual patients; for example, Patient A with 55% of viable tumour cells and mild TILs post-Tx, 0% and 2% of fibrosis at BL and post-Tx, respectively, and 13% increase of tumour size from BL, has a risk of recurrence of 82%; while Patient B, with the same % of viable tumour cells, but moderate TILs post-Tx, 0% and 35% of fibrosis at BL and post-Tx, respectively, and 12% decrease of tumour size from BL, has a lower risk of recurrence of 20%.

NeoRisk can accurately predict recurrence after NeoIT, which may help tailor adjuvant treatment and radiological surveillance interval based on the predicted risk of recurrence for individual patients.