Positive outcomes
From the studies done so far, CD47, a “don’t eat me” signal, is over expressed on all human solid tumour cells. Using mouse xenotransplant models, treatment of anti-CD47 antibody has proven effective against seven tumours. It was found that the efficacy of the treatment was inversely correlated with tumour size. Mice with smaller tumours had full recovery and those with larger tumours failed to metastasize. Fully recovered mice did not redevelop cancer after four months which suggests this treatment may be possibly used as a long-term anti-cancer treatment. CD47 can also be a potential diagnostic tool for cancer due to it abnormally higher expression levels in malignant cells. These are great outcomes from the studies, and further research is required before the treatment is deemed effective in humans.
Limitations
The anti-CD47 antibody presents a novel way of combatting cancer however it is not without limitations. The success of obliterating cancer is dependent on the volume of the tumour. Combination treatments are beginning to be explored but the replacement of radiotherapy and chemotherapy is much preferred to reduce adverse effects on normal cells. The increased concentration of in situ macrophages would perhaps offer a better solution to eliminate bigger and more aggresive tumours.
Future directions
Weissman and his colleagues have identified a number of future directions for this particular study, as outlined below:
- Translate the results generated so far into humans through phase 1 and phase 2 clinical trials within the next two years.
- Investigate the use of CD47 as a prognostic marker for cancer patients
- Examine the ability of anti-CD47 antibodies to target metastases before and after surgical resection of primary tumours and hence treat metastatic disease
- Apply current findings to different circumstances which affect CD47-SIRPa interaction