Velmanase alfa for treating alpha-mannosidosis

1 Recommendations

1.1 Velmanase alfa is not recommended, within its marketing authorisation, for treating the non-neurological signs and symptoms of mild to moderate alpha-mannosidosis.

1.2 This recommendation is not intended to affect treatment with velmanase alfa that was started in the NHS before this guidance was published. People having treatment outside this recommendation may continue without change to the funding arrangements in place for them before this guidance was published, until they and their NHS clinician consider it appropriate to stop. For children and young people, this decision should be made jointly by them, their clinician, and their parents or carers.

Why the committee made these recommendations

Alpha-mannosidosis is a rare and serious condition that severely affects the quality of life of people with the condition, and their families and carers.

Clinical trial evidence suggests that velmanase alfa is a potentially promising treatment. But, because of important limitations in the available evidence, the exact size and nature of the clinical benefits (both in the short- and longer-term) are highly uncertain.

There are also uncertainties in the economic modelling. In particular, there is very little observed evidence to inform the model, and most of the data used in the model is based on expert opinion rather than clinical trial evidence. Also, the assumed benefits of velmanase alfa treatment in the model are very uncertain.

Overall, although velmanase alfa is a promising treatment, the benefits it provides are highly uncertain. The cost-effectiveness estimates for velmanase alfa are higher than those considered value for money in the context of a highly specialised service. Taking into account all the evidence and the factors affecting the decision, including the extremely rare and disabling nature of alpha-mannosidosis, velmanase alfa is not recommended for use in the NHS.