Market size for a treatment for CJD
By the time that CJD shows symptoms already damage has taken place to the brain and treatment could only be expected to slow down the rate at which this damage takes place. The reason for this is that there is low levels of reversable pathology that are present although, because of the inflammation that is present there is some, there is some.
A drug that was able to stop the inflammatatory process that is itself involved with the apoptosis that causes the spongiform change in the brain, could actually cause some improvement in the clinical condition of the patient. However currently there is no indication that recovery is likely.
A good example of the late stages of the disease when symptoms start to appear is given in cattle. About 15% of the cases of BSE are diagnosed as not having BSE when they are examined under the microscope. This is even when examined by experts in the field. The suggestion from the VLA results is that this is due to early diagnosis of the condition by veterinary surgeons and farmers, who are used to the personality of the cattle.
It is currently difficulty to be certain of the amount of actual neuronal damage at the early symptomatic period, however it may well be worthwhile producing a drug for humans that would be able to prevent the progression of the disease.
Case numbers for CJD
The complexity for this is not so much in the calculation of the case numbers for sporadic CJD, which causes the death of 1 person in 1,000,000 in the world annually, or an assessment of the proportion of true cases that this represent (as this is now considered to be high), but rather an assessment of the proportion of cases for which treatment would be considered.
Currently this would depend on the value of the drug involved, its availability to the patients in the third world, and the price that it would need to cost. Currently, it should be suggested that approximately 25% of the world's cases of CJD should expect to be treated with a reasonable drug at a market price, which would depend on the country to which it was being sold. This would represent only 1000 new cases annually but an annual price at possibly ￡10,000 per year.
The age at diagnosis for CJD is approximately 60 years and the life expectancy in countries in which this is being diagnosed regularly is generally over 70 years. Other forms of CJD (familial, nosocomial) are relatively low in numbers and figures to include these might increase the CJD statistics by 10%.
For a drug that would be able to treat and prevent the further spread of CJD as a short course (i.e. the penicillin of CJD)
- For sporadic CJD an annual market would be ￡10,000,000 annually but would not be expected to build up.
- If 10,000,000 cases in UK and 10,000,000 in Europe. The annual market would be expected to build up over the next 10 years to ￡50,000,000,000 but would not be expected to build up; indeed it would be expected to fall over the following 30-50 years to zero.
- If 1000 cases in UK and 1000 cases in Europe. The annual market would be expected to build up over the next 5-10 years to ￡5,000,000 but would not be expected to build up; indeed it would be expected to fall over the following 30-50 years to zero.
For a drug that would be able to treat CJD but not be able to stop further spread should the drug be withdrawn (as hoped for quinacrine):
- For sporadic CJD an annual market would build up over 10 years from ￡10,000,000 annually to approximately ￡100,000,000 annually. (taking 1000 new cases treated annually for 10 years at ￡10,000 per patient)
- For vCJD : If 10,000,000 cases in UK and 10,000,000 in Europe. The annual market would be expected to build up over the next 10 years to ￡200 billion and to a total market over the next 50 years to around ￡8,000 billion. This must be looked on as unrealistic currently as there would be other treatments appearing and such a high market would be impossible to health care funding.
- For vCJD : If 1000 cases in UK and 1000 cases in Europe. The annual market would be expected to build up over the next 5-10 years to ￡20,000,00 and the total market over the next 50 years may be ￡1 billion. This may not be unreasonable but the ability of any one treatment to retain the market over this period may be unlikely.
For a drug that slows the progression of the disease (as hoped for flupirtine)
This drug could be used for a limited period after the diagnosis of the disease and as a result the market for it would be several times the size for the single course drug.