New clinical trial data presented at the American Society for Clinical Oncology (ASCO) annual meeting in Chicago reveals that Enhertu (trastuzumab deruxtecan) significantly outperforms standard chemotherapy in treating HER2-low breast cancer, reducing the risk of disease progression by 38%. The findings intensify pressure on UK regulators to reconsider access restrictions that currently deny the treatment to approximately 1,000 women annually in England and Wales.
Trial Results Demonstrate Superior Efficacy
The Destiny-Breast06 study, involving 866 women with advanced HER2-low breast cancer, showed patients receiving Enhertu lived without disease progression for an average of 13.2 months compared to 8.1 months for those on chemotherapy. Survival rates after 12 months reached 87% for Enhertu patients versus 81.1% for the chemotherapy group.
Dr Giuseppe Curiglian, professor of medical oncology at the University of Milan and author of the latest findings, stated the drug "could become the new standard of care" for the disease. The trial revealed that equivalent to six in 10 patients responded to Enhertu treatment - twice as many as those receiving chemotherapy.
"Participants that received trastuzumab deruxtecan lived longer without their disease progressing or causing death," Curiglian explained, noting the trial demonstrated benefits for the first time in patients with HER2-ultralow levels and those who had never received chemotherapy.
Access Disparity Creates Treatment Inequality
While Enhertu has been made available to patients in Scotland and Northern Ireland, the National Institute for Health and Care Excellence (NICE) rejected the drug for England in March, citing cost-effectiveness concerns. Women in Wales also remain denied access to the treatment, which is available in 13 other European countries, as well as the US and Canada.
The decision affects patients with HER2-low breast cancer, which represents approximately 50% of all breast cancers according to Breast Cancer Now. The drug is already licensed for patients with HER2-positive breast cancer in England, despite results showing similar effectiveness across HER2 expression levels.
Sophie Blake, 51, from Brighton, was diagnosed with HER2-low breast cancer in December 2020 before learning it had spread to her lungs and liver in May 2022. The former television presenter, whose cancer is currently under control, described the access denial as particularly devastating given limited treatment options.
"This is yet more evidence of the precious extra time this treatment could give us," Blake said. "We know women in Scotland whose lives it's changed, it's not that it just gives you an extension, it's also the quality of life. To us, these wonder drugs are everything — I want to watch my daughter go to university, get married and have children, Enhertu could make that difference to women."
Clinical Significance and Safety Profile
The new data builds on previous studies demonstrating Enhertu improved overall survival rates by more than six months. Known as trastuzumab deruxtecan, it represents the first licensed targeted treatment for patients with HER2-low cancer that cannot be surgically removed or has metastasized.
Dr Erica Mayer, director of breast cancer clinical research at the Dana-Farber Cancer Institute in Boston, described the results as "definitely exciting news" that will impact clinical practice. However, she noted that women receiving Enhertu experienced more side effects compared to those on chemotherapy, indicating the treatment may not be appropriate for every patient.
Ongoing Negotiations and Advocacy Efforts
Dr Simon Vincent, director of research at Breast Cancer Now, called the access denial "utterly unacceptable" given mounting clinical evidence. "These people are desperately counting on NICE, NHS England, Daiichi Sankyo and AstraZeneca to find a solution in their current talks and to urgently make this treatment available for them," he stated.
A petition by Breast Cancer Now has gathered more than 260,000 signatures calling for urgent access to the treatment. NICE officials expressed being "extremely disappointed" at their inability to recommend Enhertu for advanced HER2-low breast cancer on cost grounds, noting that guidance has been "paused" while discussions continue.
Health officials indicated that at a recent meeting, drug manufacturers Daiichi Sankyo and AstraZeneca had increased their price proposal. A NICE spokesman emphasized that "a price making it a cost-effective use of NHS resources being offered by Daiichi Sankyo and AstraZeneca could resolve this issue almost immediately."
The access disparity has created what campaigners describe as a sense of "betrayal and disbelief" among patients who find themselves spending precious time fighting for treatment access rather than focusing on time with family and friends.
