The National Institute for Health and Care Excellence (NICE) invited the manufacturer (Shire Pharmaceuticals) of pegylated liposomal irinotecan hydrochloride trihydrate (liposomal irinotecan) to submit clinical and cost-effectiveness evidence for its use in combination with 5-fluorouracil (5-FU) and folic acid/leucovorin (LV) for treating patients with pancreatic cancer following prior treatment with gemcitabine as part of the institute's Single Technology Appraisal process. The Liverpool Reviews and Implementation Group at the University of Liverpool was commissioned to act as the Evidence Review Group (ERG). This article presents a summary of the company's evidence, the ERG review and the resulting NICE guidance (TA440), issued on 26 April 2017. Clinical evidence for liposomal irinotecan + 5-FU/LV versus 5-FU/LV was derived from 236 patients with metastatic pancreatic cancer in the multinational, open-label, randomised controlled NAPOLI-1 trial. Results from analyses of progression-free survival and overall survival showed statistically significant improvements for patients treated with liposomal irinotecan + 5-FU/LV compared with those treated with 5-FU/LV. However, 5-FU/LV alone is rarely used in National Health Service clinical practice for patients with metastatic pancreatic cancer previously treated with gemcitabine. The company, ERG and Appraisal Committee (AC) all agreed that oxaliplatin + 5-FU/LV is the most commonly used treatment. Oxaliplatin + 5-FU/LV was compared with 5-FU/LV in two trials identified by the company. However, the company and the ERG both considered attempts to compare the efficacy of liposomal irinotecan + 5-FU/LV with oxaliplatin + 5-FU/LV to be methodologically flawed; not only was there heterogeneity between trials and their populations but also the proportional hazards assumption required to conduct a robust indirect treatment comparison (ITC) was violated. Nonetheless, data derived from an ITC were used to inform the company's economic model. Using the discounted patient access scheme price for liposomal irinotecan + 5-FU/LV, the company reported an incremental cost-effectiveness ratio (ICER) per quality-adjusted life-year (QALY) gained of £54,412 for the comparison with oxaliplatin + 5-FU/LV. The ERG considered that the company's base-case cost-effectiveness results for the comparison of liposomal irinotecan + 5-FU/LV versus oxaliplatin + 5-FU/LV were underestimates and should be interpreted with extreme caution. Following implementation of a number of model amendments, the ERG's modified exploratory ICER for the comparison of liposomal irinotecan + 5-FU/LV versus oxaliplatin + 5-FU/LV was £106,898 per QALY gained. The AC accepted the majority of the ERG's amendments to the model, and also highlighted that the total QALYs for oxaliplatin + 5-FU/LV were lower than for 5-FU/LV in the company's model, which the AC considered to be clinically implausible. The AC therefore considered results from exploratory analyses, undertaken by the ERG, which included altering the QALY difference between liposomal irinotecan + 5-FU/LV and oxaliplatin + 5-FU/LV by ± 10%. These analyses resulted in ICERs for the comparison of liposomal irinotecan + 5-FU/LV versus oxaliplatin + 5-FU/LV of between £201,019 per QALY gained to liposomal irinotecan + 5-FU/LV being dominated by oxaliplatin + 5-FU/LV. Therefore, despite uncertainty around the clinical-effectiveness evidence and cost-effectiveness results, the AC was confident that the ICER was in excess of £50,000 per QALY gained. The final guidance issued by NICE is that liposomal irinotecan + 5-FU/LV is not recommended within its marketing authorisation for treating metastatic adenocarcinoma of the pancreas in adults whose disease has progressed after gemcitabine-based therapy.