Mogamulizumab for Previously Treated Mycosis Fungoides and Sézary Syndrome: An Evidence Review Group Perspective of a NICE Single Technology Appraisal

The National Institute for Health and Care Excellence (NICE) invited the manufacturer (Kyowa Kirin) of mogamulizumab (Poteligeo®), as part of the single technology appraisal process, to submit evidence for its clinical and cost-effectiveness for previously treated mycosis fungoides (MF) and Sézary syndrome (SS). Kleijnen Systematic Reviews Ltd, in collaboration with Maastricht University Medical Centre, was commissioned to act as the independent evidence review group (ERG). This paper summarises the company submission (CS), presents the ERG’s critical review of the clinical and cost-effectiveness evidence in the CS, highlights the key methodological considerations and describes the development of the NICE guidance by the Appraisal Committee. Based on a systematic literature review, one randomised controlled trial, MAVORIC, was identified showing favourable results in patients with MF and SS. However, MAVORIC compared mogamulizumab to vorinostat, which is not standard care in the NHS, and there is uncertainty due to the study design, specifically crossover of patients. Based on a “naïve comparison of results from the vorinostat arm of the MAVORIC study and the physician’s choice arm (methotrexate or bexarotene i.e. United Kingdom [UK] standard treatments) of the ALCANZA study as well as comparison to Phase II bexarotene data”, the company considered vorinostat to be “a reasonable proxy for current standard of care in the NHS”. The ERG considered, based on the limited data available, that the comparability of vorinostat (MAVORIC) and physician’s choice (ALCANZA) could not be established. In response to the Appraisal Consultation Document, the company provided an unanchored matched adjusted indirect comparison (MAIC) of mogamulizumab with UK standard care by analysing Hospital Episode Statistics (HES) data. However, given the high risk of bias of an unanchored MAIC, these results needed to be regarded with a considerable degree of caution. The economic analysis suffered from uncertainty because there was no trial evidence on the comparator in the England and Wales National Health Service (NHS), and it was unclear to what extent the trial (MAVORIC) comparator (vorinostat) was comparable to standard care, referred to as established clinical management (ECM) in the NHS. The evidence for overall survival had not reached maturity and was confounded by treatment switching, for which different crossover adjustment methods produced large variations in life years. Caregiver utilities were applied in the analysis, but there was a lack of guidance on their application and whether these were indicated in this appraisal. After consultation, the company updated the economic analysis with the MAIC. Incremental cost-effectiveness ratios comparing mogamulizumab against ECM were (depending on whether the HES or MAVORIC comparison were used) £31,030 or £32,634 per quality-adjusted life years (QALYs) gained according to the company’s base case and £38,274 or £80,555 per QALY gained according to the ERG’s base case. NICE did not recommend mogamulizumab for treating MF or SS in adults who have had at least one previous systemic treatment. This decision was subsequently appealed, and an appeal decision has been reached.