Clinical trials have shown that Enhertu (trastuzumab deruxtecan) could extend the lives of patients with incurable breast cancer by as much as two years.
Baroness Morgan, the chief executive of Breast Cancer Now, described the decision as “devastating”.
The National Institute for Health and Care Excellence (NICE) said that it recognised the drug was a “potentially significant development” but that “cost-effectiveness estimates were too high”.
The watchdog said that it needed more information on the drug and asked the manufacturer, Daiichi Sankyo, to address “uncertainties in its economic model”.
The drug is the first of its kind to be licensed and targets a new subtype of breast cancer known as HER2-low – a reference to the protein on the breast cancer cells that stimulate the tumour’s growth.
Early estimates suggest as many as half of the 56,000 people diagnosed with breast cancer in the UK each year could have the newly classified subtype of the cancer.
The treatment, which has been approved in the United States and Europe, works by attaching to the protein and stopping it from growing, and can also help the body’s immune system to identify and attack the cancer.
‘Number of uncertainties’
It is available on a conditional basis in Britain and through a “managed-access agreement” with NHS England, allowing some patients to benefit.
Up to 1,000 NHS patients would have benefited from the treatment if it had been approved, NICE said.
The numbers are relatively small because women will have to be diagnosed with HER2-low breast cancer that cannot be surgically removed or has spread to other parts of the body, and have already had chemotherapy.
Lady Morgan urged NICE and Daiichi Sankyo “to work together to explore all possible solutions to ensure this provisional decision is reversed without delay”.
She said: “This could have been a crucial moment to change practice and for the first time, provide an effective, targeted treatment for patients whose breast cancer is HER2-low.
“Instead, trastuzumab deruxtecan, and the invaluable extra time it could bring patients to do the things that matter most to them, remains out of reach.”
The treatment, which has a market cost of about £1,500 per dose, is delivered intravenously every three weeks.
Helen Knight, the director of medicines evaluation at NICE, said: “There were a number of uncertainties in the company’s economic model, this meant that even when taking into consideration the condition’s severity and its effect on quality and length of life, the cost-effectiveness estimates were too high for it to be recommended for use in the NHS.
“The committee has identified a number of areas for clarification by the company before its next meeting and NICE will work with the company to address these.”