Targeted therapy extends breast cancer survival
About 150 women are diagnosed with
breast cancer in the UK every day. It is one of the leading causes of death amongst
females aged 50-64. We all know someone who has been affected by the disease.
Now a clinical trial tracking a
combination of drug therapies for nearly ten years has reported its final analysis.
The study, which originally began in
2013, had already shown the longest average survival reported to date in any
advanced breast cancer Phase III clinical trial.
However, whether overall survival
would also be extended by the targeted therapy was not known.
The MONALEESA-2 clinical trial
Endocrine therapy targeting the hormones
that fuel breast cancer growth is standard care for postmenopausal women with
advanced breast cancer.
However, many patients develop
resistance to treatment, which requires the use of sequential therapies that
have alternative ways of working.
The MONALEESA-2 trial was set up to discover whether new ways of
targeting hormone receptor positive, HER2 negative, advanced breast cancers
worked better than traditional treatments.
The trial enrolled 668 women with
advanced breast cancer in 223 centres across 29 different countries. The
patients were randomly assigned a new targeted drug Ribociclib plus Letrozole (an aromatase inhibitor drug originally licensed in
1996), or a placebo plus Letrozole.
The trial was randomised, placebo-controlled and double-blind (where neither patients
nor doctors know who is receiving the treatment or a placebo). Such trials are
the gold standard of clinical assessment and validation.
What did the new treatment show?
The final analysis of the trial showed that survival was
significantly longer among those receiving Ribociclib plus letrozole than among
the placebo control group.
After follow-up just over 6 years
into the trial, 181 deaths had occurred among the Ribociclib group and 219
among the placebo group. Ribociclib plus letrozole thus showed a significant
overall survival benefit.
With the trial now finished, median
overall survival has been shown to be 63.9 months compared with 51.4 months for
the placebo (plus traditional chemotherapy) group.
In plain English, the drug
therapy has been proven to extend survival in those with advanced breast cancer
by over a year, compared to standard treatment.
How the targeted therapy treats breast cancer
Targeted therapies
aim at specific characteristics of cancer cells, such as a protein that allows
the cancer cells to grow in a rapid or abnormal way. Targeted therapies are
generally less likely than chemotherapy to harm normal, healthy cells.
Ribociclib is a targeted therapy drug called a cancer growth
inhibitor. It targets the growth of HER2 (human
epidermal growth factor receptor 2) in the body, a gene that can feature in the
development of breast cancer.
The HER2 gene makes
proteins which form receptors on breast cells. The receptors help to control
how breast cells grow, divide and multiply.
In about 10%-20% of
breast cancers the HER2 gene becomes faulty and makes too many copies of
itself. This is called HER2 gene amplification. The extra genes tell breast
cells to make too many receptors. This causes the cells to grow in an
uncontrolled way.
Testing for hormone
receptors is therefore a key step in treating breast cancer, because the
results will help decide whether the cancer is likely to respond to hormonal
therapy medicines, like Herceptin.
If a breast cancer
is hormone receptor positive, it means tumour growth is fuelled by the hormones
oestrogen, progesterone, or possibly both. Most breast cancers are hormone
receptor positive.
It the cancer is HER2
negative, it means it does not have human epidermal growth factor receptor (HER2)
proteins. That means it will not respond to treatments that target HER2
protein, like Herceptin, but it may respond to therapies that specifically
target it, like Ribociclib.
More than two out of every three breast cancers are both hormone receptor positive
and HER2-negative. This is why Herceptin is only suitable for a smaller
proportion of breast cancers, whilst many more patients may benefit from
Ribociclib.
Risks associated with treatment
Although the treatment has now
been proven to extend survival, like many drugs it does have side-effects and
some risks.
Nearly three-quarters of patients
taking the drug developed Neutropenia, which occurs
when you have too few neutrophils, a type of white blood cells.
While all white blood cells help
your body to fight infections, neutrophils are important for fighting certain
infections, especially those caused by bacteria.
Neutropenia can
make you more vulnerable to infections. When neutropenia is severe, even the
normal bacteria from your mouth and digestive tract can cause serious illness.
The drug caused more
people to feel nauseous than those in the control group and the rate of
infections, fatigue and diarrhoea that occurred were all higher too.
One death during the trial was
considered to be related to the drug, which means all patients taking the drug are
monitored with regular ECG’s too.
However, even with
the risks associated with the treatment, the proven extension in survival means
many patients are likely to be able to benefit from the treatment in the future.
About Occupational Health Assessment Ltd
Occupational Health Assessment
Ltd provides rapid access to expert
occupational health support for businesses across the
United Kingdom. Appointments are available within two days.
With a unique occupational health assessment service, fitness certifications and access to clinics in Belfast, Birmingham, Bradford, Brighton, Bristol, Cardiff, Coventry, Derby, Edinburgh, Glasgow, Hull, Leeds, Leicester, Liverpool, London, Manchester, Newcastle, Northampton, Nottingham, Plymouth, Portsmouth, Reading, Sheffield, Southampton, Stoke, Surrey and more, the business provides
high quality, expert medical advice.
Please contact us for
further information or assistance.