ABSTRACT
Background: Treatment with tumor-Infiltrating Lymphocytes (TIL) is an innovative therapy for advanced melanoma
with promising clinical phase I/II study results and likely beneficial cost-effectiveness. As a randomized controlled
trial on the effectiveness of TIL therapy in advanced melanoma compared to ipilimumab is still ongoing, adoption
of TIL therapy by the field is confronted with uncertainty. To deal with this, scenario drafting can be used to
identify potential barriers and enables the subsequent anticipation on these barriers. This study aims to inform
adoption decisions of TIL by evaluating various scenarios and evaluate their effect on the cost-effectiveness.
Methods: First, 14 adoption scenarios for TIL-therapy were drafted using a Delphi approach with a group of
involved experts. Second, the likelihood of the scenarios taking place within 5 years was surveyed among
international experts using a web-based questionnaire. Third, based on the questionnaire results and recent
literature, scenarios were labeled as being either “likely” or “-unlikely”. Finally, the cost-effectiveness of TIL treatment
involving the “likely” scored scenarios was calculated.
Results: Twenty-nine experts from 12 countries completed the questionnaire. The scenarios showed an average
likelihood ranging from 29 to 58%, indicating that future developments of TIL-therapy were surrounded with quite
some uncertainty. Eight of the 14 scenarios were labeled as “likely”. The net monetary benefit per patient is
presented as a measure of cost-effectiveness, where a positive value means that a scenario is cost-effective. For six
of these scenarios the cost-effectiveness was calculated: “Commercialization of TIL production” (the price was
assumed to be 3 times the manufacturing costs in the academic setting) (−€51,550), “Pharmaceutical companies
lowering the prices of ipilimumab” (€11,420), “Using TIL-therapy combined with ipilimumab” (−€10,840), “Automatic
TIL production” (€22,670), “TIL more effective” (€23,270), “Less Interleukin-2” (€20,370)