The treatment was found to increase by half the survival of patients with advanced breast cancers that have low levels of the HER2 protein.
A new drug hailed as a “magic bullet” and “a new standard of care” is now available to breast cancer patients in Cork, Limerick, and Dublin hospitals as part of international clinical trials.
The treatment, which targets the cancer directly without affecting the body’s healthy cells, was found to increase by half the survival of patients with advanced breast cancers that have low levels of the HER2 protein.
Tumour growth in trial participants stopped for an average of 10 months, twice as long as other patients who received standard chemotherapy.
When US-based scientists revealed the research findings for the drug trastuzumab deruxtecan (brand name Enhertu) at an international cancer research conference in June, they received a standing ovation from their peers.
“This is a new standard of care,” Dr Eric Winer, breast cancer specialist and head of the American Society of Clinical Oncology, which hosted the conference, said of the research. “It affects a huge number of patients.”
Now, two separate clinical trials involving the drug have opened in Ireland as part of global studies.
Recruiting patients for trial
The ‘DESTINY-Breast12’ trial is recruiting patients with advanced HER2-positive breast cancer.
Trial participants will be enrolled into one of two groupings, according to whether or not their cancer has spread to the brain.
The ‘DESTINY-Breast05’ trial is recruiting patients with HER2-positive primary breast cancer who are at a higher risk of their disease recurring after initial treatment.
This study will compare Enhertu with another targeted cancer treatment to compare levels of survival in patients.
“Nearly every study that has been done with this drug has been a positive study, so people are really excited about it,” Prof Roisin Connolly of Cork University Hospital, who is the Irish lead for ‘DESTINY-Breast12’ and Director of the University College Cork Cancer Trials Group, said.
“This is a class of drug which is called an antibody drug conjugate and these are quite interesting.
“It’s that ‘magic bullet’ sort of story you might hear about — the treatment coming straight to the cancer cell.”
“In the case of trastuzumab deruxtecan, it is attracted to HER2 in the cancer cells. It brings a strong chemotherapy that is bound to the antibody straight to the cancer cell and so minimises some of the regular chemo side effects.”
About 15% of all breast cancer cases are HER2-positive. However, while many advances have been made in treatments for these patients, those with low levels of the protein have escaped the benefits of these new therapies.
As a result, around half of all patients that have seen their breast cancer spread to other parts of the body have low levels of HER2.
The US-based research, published in , found that advanced breast cancer patients with the new drug survived for an average of 24 months, compared to just under 17 months for those who received standard chemotherapy.
“It is unheard of for chemotherapy trials in metastatic breast cancer to improve survival in patients by six months,” Dr Halle Moore of the Cleveland Clinic, who enrolled some trial participants, told .
In recent weeks Enhertu has been approved in the US and EU for use in patients with advanced HER2-positive breast cancer who have seen other anti-HER2 treatments fail.
The drug has a wholesale price of around €14,000 per patient every three weeks.
CEO of Cancer Trials Ireland Eibhlín Mulroe hailed Irish involvement in leading cancer research but pointed to challenges facing future patient care here.
Challenge of treatment costs
“The caveat from all of it is, how are we going to afford it all, because some of these drugs are high cost,” Ms Mulroe said.
“I think that’s going to be a question for the whole world — when we find these new treatments, how accessible are they for people?
“We even see here that there are drugs that are accessible in the Republic of Ireland that aren’t accessible in Northern Ireland.
“There have been examples of trials that we couldn’t open in Northern Ireland because the standard of care wasn’t provided for in the northern system whereas it was in the southern system.”
The DESTINY-Breast12 and DESTINY-Breast05 trials are sponsored by pharmaceutical companies AstraZeneca and Daiichi Sankyo and will be run in Cork University Hospital, Dublin’s St Vincent’s University Hospital, Mater Misericordiae University Hospital, and St James’s Hospital, and University Hospital Limerick. Further information on trial eligibility is available on cancertrials.ie.
“We know that when patients participate in clinical trials, they have better outcomes overall,” Prof Connolly added.
“When we are meeting with patients in the clinic, we are always thinking ‘is the patient eligible for a clinical trial?’.
“It is so important that cancer clinical trials teams across Irish cancer centres can offer these promising options to our patients.”
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