Four in six melanoma patients trialling a personalised cancer vaccine experienced no recurrence of the disease within the following 25 months.
The other two patients, who suffered from later-stage cancer which had already spread to their lungs, were treated with an anti-PD-1 therapy as well as the personalised treatment, after which the tumours regressed completely and neoantigen-specific T-cells increased.
A second study involved administering personalised vaccines to 13 patients, of which eight were entirely cancer free after 23 months.
The implications of these early-stage studies, both published in Nature, are significant, and researchers are calling for further tests on a larger sample size to calculate the efficacy of the treatment, and devise how safe and marketable the drugs are.
What are cancer vaccines?
Rather than referring to preventative medicine, as is the case with commonly-known vaccinations such as the flu vaccine, the studies focussed on "therapeutic vaccines," which are designed to trigger and strengthen the immune system's ability to fight cancerous cells that have already developed.
The vaccines trialled in this year’s ground-breaking studies use mutated proteins that have significant similarities to the proteins of the tumour, yet appear foreign to the body, allowing the immune system to kick in to destroy the proteins of the vaccine, and in doing so attack the cancer itself.
One significant difficulty in vaccinating against cancers is the body’s central tolerance, which prevents the immune system from targeting its own cells - including tumours. This means the immune system is unable to recognise tumours as disease, leading cancer patients to require harmful therapies such as chemotherapy to rid themselves of cancerous cells.
This vaccine responds to the problem by training the immune system to target the body’s own cancerous cells, without causing it to attack healthy tissues.
How is the medicine personalised?
When a cancer-causing mutation occurs in a cell, the cell is marked by neoantigen particles, which differentiate them from healthy cells. These particles differ from person to person, and so any medicine that targets them will need to be personalised to a patient’s specifications.
By creating mutated proteins with patient-specific neoantigens attached, the immune system can be tricked into noticing them on the foreign molecules, and generalising their targeting the the neoantigen-marked tumour cells as well.
Thanks to massive parallel sequencing technology, which quickly determines the DNA codes in discrete genetic material, researchers are able to evaluate huge numbers of neoantigens to devise personalised medicines that will bind with patient-specific immune cells.
Are these new medicines game-changers?
While these trials are only preliminary, they represent a significant step forward in the way we think about cancer treatments. Furthermore, they demonstrate the power of personalised medicine to tackle life-threatening diseases in less risky and damaging ways than current therapies provide.
This advance in the personalisation of medicine is particularly good news for women or minority ethnicities, who are often treated with one-size-fits-all medications, developed based on clinical data drawn from majority male or caucasian test subjects.
By examining the efficacy of medicines that relate specifically to a patient’s genetic makeup, we can respond and adapt on a case-by-case basis, understanding individuals’ needs more clearly, and responding to their illnesses with targeted treatments.