OBJECTIVES: While standard parametric extrapolation has been the mainstay in economic modelling, more flexible methodology has been increasingly used in submissions to health technology assessment (HTA) agencies. HTA assessments of economic models submitted for immuno-oncology (I-O) products were reviewed to determine the extent to which cure fraction modelling methods were used by manufacturers and the reception of these techniques by HTA agencies.

METHODS: Publicly available National Institute for Health and Care Excellence (NICE) and the Canadian Agency for Drugs and Technologies in Health (CADTH) websites were searched for assessments of I-O products from which details regarding submitted survival modelling methodology and HTA critiques and reanalysis were extracted.

RESULTS: Survival modelling using a cure fraction was identified in three submissions to NICE and one submission to CADTH. Submissions to NICE included one each for renal cell carcinoma (nivolumab), non-small cell lung cancer (atezolizumab), and relapsed or refractory systemic anaplastic large cell lymphoma (brentuximab vedotin). The submission to CADTH using this methodology was for non-small cell lung cancer (atezolizumab). There was variability among submitted models which assumed either a cure fraction from model time zero, or that all patients surviving to a specified timepoint (5-years) were cured. Although clinical experts consulted by NICE and CADTH supported the hypothesis that immunotherapies may lead to a long-term durable response for a proportion of patients, it was noted that there was currently a lack of long-term evidence to support a cure rate for these therapies in these settings. Citing a lack of evidence, NICE and CADTH rejected the cure rate assumptions submitted in all manufacturer base case analyses.

CONCLUSIONS: Despite the clinical evidence for the plateau of long-term survival for a proportion of patients treated with I-O therapies and the availability of survival modelling techniques, lack of long-term data prevents acceptance by HTA agencies.