One of the emerging treatments for cancers if immunotherapy that breaks the cycle of immunological tolerance that cancers create around themselves. Two key break throughs, anti-CTLA4 antibody therapy and anti-PD1 or anti-PD1L therapy have been shown to induce durable immune responses. In the case of the older treatment, anti-CTLA4 antibody therapy has now been shown to produce 25% and 20% 5 and 10 year survivals for metatatic melanoma – a disease usually fatal within 12 months of diagnosis.
Apart from the long term survivals there are two other exciting features of these treatments. Firstly they can probably be used in most, if not all, cancer types although the chances of response does seem to vary. In the case of anti-PD1 therapy cancers such as NSCLC have response rates in excess of first-line chemotherapy. Secondly, early evidence suggests that these treatments can be combined safely and with much greater activity (doubling of monotherapy). At the moment there is no long term data around combination therapy.
Let’s assume that combination anti-CTLA4 therapy and anti-PD1 therapy does provide long term ‘clinical cures’. A speaker at the meeting I was just at suggested 40-50% long term cure for metastatic melanoma. Based on the current pricing of ipilimumab (anti-CTLA4 antibody) then a combination treatment could well cost in excess of $250K per person. THis also may not abrogate the need for other targeted or chemotheapy and the immunotherapies tend to work slowly so patients presenting with advanced disease will still need initial therapy to control their tumour burden whilst the immunotheapy works.
If this strategy, for arguments sake, improved the median survival to 50-60% and the 10 year survival to 40% then investinging $250K upfront may well be cost-effective when translated into a cost per year of life saved – particularly if the treated population is of a productive tax-paying age.
But for Governments the upfront cost may still be too high if this treatment was applicable to all or most solid tumours. In part it may depend on how the regimen is ultimately delivered. If the therapy works with a short course of treatment and minimal or no maintenance therapy, and if additional theapies like targeted therapy or chemotherapy are not required then this treatment may well be viable. If many patients need additional targeted therapy or treatment escape is early then it may not be viable. Ideally poly-immunotherapy will increase survival and avoid the need for other costly therapies.