The health secretary has ordered a meeting with a primary care trust which will not provide a woman suffering from breast cancer with the drug Herceptin.
Ms Barber said she is being "left to die"
North Stoke Primary Care Trust (PCT) told Elaine Barber it was not convinced the drug was safe or cost-effective.
Health Secretary Patricia Hewitt said that this ruling conflicts with decisions made by other Trusts.
Ms Barber, 41, from Staffordshire, will now take the PCT to the High Court - the case should be heard within a week.
Last month ministers said all women with early stage breast cancer would be tested to see if the drug would help.
Ms Hewitt said she was "very concerned" by the trust's decision not to give the drug to the mother-of-four on the NHS.
She added: "I have urgently asked the PCT to show the Department the evidence they have used as the basis of their decision not to fund Herceptin.
"On the basis of the published evidence other PCTs have agreed to fund Herceptin for individual women with early stage breast cancer whose clinicians recommend that the drug is suitable for them providing they are aware of the potential risks.
"We have already arranged an urgent meeting with the PCT and SHA later this week to discuss their approach to funding Herceptin.
"A fortnight ago I made it clear that PCTs should not refuse to fund Herceptin solely on the grounds of its cost."
A statement from the trust said: "The PCT has reviewed in detail the published evidence of the clinical effectiveness of Herceptin in early breast cancer and recognises that this has the potential to be a significant advance in treatment.
"At this stage however the evidence of this as a cost-effective use of the finite health resources available for North Stoke patients is not confirmed.
"It would therefore be premature to agree to introduce it as a routine treatment.
"To do so could seriously affect the availability of care to other patients, including those with other cancers."
Mother-of-four Ms Barber said she is being "left to die" after losing her appeal.
She added: "Is it safer to give me the drug or safer not to give it to me - and let me die? I know which option I prefer to take.
"I need this drug to help me survive - without it I will die."
The drug, which can cost £20,000 a year for a course of treatment, is currently licensed only for use in women with advanced breast cancer.
An application to extend the drug's licence to cover other suitable breast cancer patients will be submitted next February.
PCTs can currently fund Herceptin treatment for women with early stage breast cancer, if they so wish.
Research has shown Herceptin can reduce the risk of tumours returning in women with early stage breast cancer.