Recent Advances in Kidney Cancer Treatment
Treatments for kidney cancer have notoriously been scarce. But options for patients are now widening. Scientists are finding new ways to fight the disease, by repurposing existing cancer medications, developing new therapies and using novel drug combinations.
Tyrosine Kinase Inhibitors
A promising innovative approach in the treatment of kidney cancer is to disrupt the very mechanisms that allow the tumour to develop and grow. This can be done with medicines already approved for the treatment of other cancers.
An example is the targeted agent cabozantinib, which is prescribed for a rare tumour that forms in the thyroid (a small hormone-producing gland at the base of the neck).
Cabozantinib belongs to a class of drugs called tyrosine kinase inhibitors (TKIs). It works by stopping the growth of cancer cells and the blood vessels these need to develop.
As part of a recent study, patients with metastatic renal cell carcinoma (RCC) were given once daily doses of cabozantinib.
Renal cell carcinoma is the most common type of kidney cancer. Metastatic means that the cancer has spread to the kidneys from the area where it started.
The results of the study, published in the Journal of Clinical Oncology, suggest that cabozantinib may be more effective than the standard kidney cancer treatment sunitinib (another tyrosine kinase inhibitor).
Patients receiving cabozantinib had progression-free survival of 8.2 months, compared with 5.6 months for those on sunitinib.
Progression-free survival is the period of time, during or after treatment, in which the cancer does not get worse.
The proportion of patients whose cancer shrunk or disappeared, called response rate, was 46 per cent with cabozantinib and 18 per cent with sunitinib.
The US Food and Drug Administration (FDA) has already approved cabozantinib for the treatment of advanced kidney cancer.
In the UK, the drug is still being appraised by the National Institute for Health and Care Excellence (NICE), and a decision is expected by June 2017.
Exciting results have been reported also for an experimental tyrosine kinase inhibitor called savolitinib.
They suggest that this oral drug could be especially useful in the treatment of people with papillary renal cell cancer (PRCC) who have a gene mutation known as c-MET.
In a recent phase II clinical trial, nearly one in five patients with this common type of kidney cancer achieved partial response following treatment with savolitinib.
Partial response means that a tumour has decreased in size by at least 50 per cent.
Immune Checkpoint Blockers
Another novel approach to the treatment of kidney cancer is to block natural pathways that tumoural cells use to ‘hide’ from the patient’s immune system.
These pathways involve the activation of, among others, a protein called PD-1.
New drugs are being developed that can neutralize this protein, allowing the immune system to detect and destroy the cancer.
They are collectively known as immune checkpoint blockers, and are a type of immunotherapy.
Among them is the drug nivolumab, which is now recommended by NICE for previously treated advanced renal cell carcinoma.
This is following a recent assessment indicating that the new drug “could extend survival, and … is a good use of NHS resources,” says Professor Carole Longson, director of NICE’s Health Technology Evaluation Centre.
Vaccine Immunotherapy for Kidney Cancer
Meanwhile, University of Texas researchers have developed another immunotherapy, in the form of a vaccine, which contains genetically-modified kidney cancer cells.
Dr. Hans Hammers, an associate professor of internal medicine at the university, said in an interview to OncLive:
“The idea is that cell-lines that have been modified in this particular manner can jumpstart an immune response.”
The vaccine is called HyperAcute Renal (HAR) immunotherapy, and is being tested in patients with renal cell carcinoma.
It has been designed in such a way that it can be used in combination with other therapies, said Hammers.
For example, it could be administered with tyrosine kinase inhibitors or checkpoint blockers, leading to more effective treatments.
Indeed, combining different therapies, each one with its own specific target, appears to be a promising way forward in kidney cancer treatment.
And several phase III clinical trials are now underway to explore this avenue.
The CheckMate 214 trial, for instance, is being conducted to assess the efficacy of the checkpoint blocker nivolumab in combination with the cancer drug ipilimumab (another checkpoint blocker) in patients with renal cell carcinoma.
In another clinical trial of RRC patients, researchers are investigating various combinations involving the drug lenvatinib – a tyrosine kinase inhibitor for thyroid cancer.
The trial is currently recruiting participants. It will help understand whether these drug combinations could be used as an alternative option to standard treatment with sunitinib alone.
Wider Options for Patients
“In the past four decades, the 10-year survival rate for patients with kidney cancer has increased from around 25 to 50 per cent,” notes Richard Kensett, managing director at Alivia Swiss Health UK.
“As scientists continue to find new ways to target the underlying mechanisms of the disease, it just seems reasonable to expect that treatment options will expand, ultimately leading to improved rates of survival.”
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