Latest study shows Enhertu, rejected by Nice, can stall growth of tumours by a year, longer than standard chemotherapy.

The treatment was blocked for NHS use in England in March. Nice said the cost the NHS was being asked to pay for Enhertu was “too high” in relation to its benefits.

A quarter of a million people have signed a petition calling for an “urgent solution” to get the treatment to women living with secondary breast cancer as soon as possible.

Thousands of women with advanced breast cancer in England and Wales are being denied a drug that cuts the risk of the disease spreading by more than a third.

Enhertu has been rolled out to patients with HER2-low breast cancer in Scotland and Northern Ireland, but the National Institute for Health and Care Excellence (Nice) has rejected it for patients in England. Women in Wales are also being denied the drug.

Compelling evidence suggests the treatment, also known as trastuzumab deruxtecan, can increase the amount of time patients live and give them more time before their disease progresses.

Now “really exciting” new data, published at the world’s largest cancer conference, suggests Enhertu is even more potent than previously thought.

Results from the Destiny-Breast06 study, presented at the American Society of Clinical Oncology (Asco) annual meeting in Chicago, show the drug can stall the growth of tumours by more than a year, significantly longer than standard chemotherapy.

Overall, Enhertu reduced the risk of cancer growing or spreading in patients with HER2-low breast cancer by 38% compared with those who received chemotherapy. The data will pile pressure on regulators to approve the drug for women in England and Wales.

Charities warned that women’s lives “will be cut short” with further delays as they called for Enhertu to be made available to women in England and Wales as swiftly as possible.

Dr Simon Vincent, director of research, support and influencing at Breast Cancer Now, said: “This promising study suggests even more people could potentially benefit from Enhertu, offering patients with HER2-low or HER2-ultralow secondary breast cancer who have already had hormone-based therapy more time to live without their cancer spreading further.

“This builds on existing evidence that this treatment can increase overall survival by over six months for people with HER2-low secondary breast cancer who have already had chemotherapy.

“Yet, despite this mounting clinical data emerging around the clear benefit Enhertu could bring patients, thousands of people with HER2-low secondary breast cancer are being denied access to Enhertu on the NHS in England, and this is utterly unacceptable.

“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.”

Sophie Blake, 51, was diagnosed with HER2-low breast cancer in December 2020 before being told it had spread elsewhere, including to her lungs and liver, in May 2022.

The former television presenter’s cancer is under control, but Enhertu would probably be a last line of treatment when needed.

Responding to the new trial results presented in Chicago, she said: “This is yet more evidence of the precious extra time this treatment could give us.

“When we’re so limited with what options are available, it’s particularly devastating. 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.”

The mother of one, from Brighton, added: “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. We’re mums, we’re sisters, we’re daughters, we’re workers, we contribute to society yet we’re being told our lives aren’t considered cost-effective.

“The most frustrating thing is that we know it’s there – they just won’t give it to us.”

All invasive breast cancers are tested for HER2 (human epidermal growth factor receptor 2) levels. Some breast cancer cells have a higher than normal level of HER2 on their surface, which stimulates them to grow.

Breast Cancer Now said about 50% of all breast cancers show low levels of HER2. It estimates that 1,000 women with HER2-low advanced breast cancer in England and Wales would benefit from Enhertu but are being denied access to the drug.

The trial presented at Ascpo involved 866 women with advanced HER2-low breast cancer. Those who received Enhertu saw the advance of the disease halted for an average of 13.2 months, compared with 8.1 months for those on chemotherapy.

Women who received Enhertu were more likely to experience side-effects compared with those on chemotherapy, which experts said showed the drug may not be the right choice for every patient.

“This will not be for every patient, but this is definitely exciting news for us that will have an impact on our practice,” said Dr Erica Mayer, director of breast cancer clinical research at the Dana-Farber Cancer Institute in Boston, Massachusetts.

The treatment was blocked for NHS use in England in March. Nice said the cost the NHS was being asked to pay for Enhertu was “too high” in relation to its benefits.

A quarter of a million people have signed a petition calling for an “urgent solution” to get the treatment to women living with secondary breast cancer as soon as possible.