Withdrawal of breast cancer drug sparks ‘deep anxiety’ among patients and clinicians

AstraZeneca’s decision to discontinue its GnRH agonist breast cancer therapy from 1 November 2026 is raising significant concerns among patients and clinicians.

The plan to cease the supply of Zoladex (goserelin) 3.6 mg subcutaneous implant has blindsided some clinicians and patient advocates alike, many of whom say they were given little warning. At stake is a cornerstone monthly therapy used in pre- and perimenopausal women with hormone receptor–positive (HR+) breast cancer.

“This decision is creating deep anxiety across our breast cancer community, especially for young women whose futures depend on continued access to Zoladex 3.6mg, a treatment that protects their fertility, supports long-term remission, and allows them to plan families after cancer,” said Rachelle Panitz, fierce advocate and Managing Director of So Brave.

AstraZeneca has cited a global commercial strategy as the reason for withdrawing the formulation.

“The discontinuation of Zoladex 3.6 mg implant from the Australian market is a global AstraZeneca decision to reduce the dose options available in some countries and not related to the safety or efficacy of Zoladex,” said AstraZeneca in a statement.

The company’s proposed alternative is a higher-dose, three-monthly Zoladex 10.8 mg implant, which is not listed on the Pharmaceutical Benefits Scheme (PBS) in breast cancer. While already used in prostate cancer, clinicians warn its application in breast cancer is far from straightforward.

“The 3.6 mg dose is used both as endocrine therapy for HR+ breast cancer in young women and for prevention of early menopause from chemotherapy. Although the real-world data on the 10.8mg dose suggests equivalence for the former use, there is no data on its use with chemotherapy,” said Professor Fran Boyle AM, Professor of Medical Oncology at the University of Sydney and Mater Hospital in North Sydney. “We also don’t know how rapidly it might wear off in patients wanting to try for a pregnancy during a break from endocrine therapy. These uncertainties will add to the concerns of a group already with many anxieties.”

Canberra-based So Brave Community Ambassador, Nicole (34), who was diagnosed with breast cancer at 32 years of age, told Health Industry Hub, “The announcement alone of the discontinuation has been excruciatingly distressing. I cannot put into words the impact if this discontinuation is to go ahead. Amongst other reasons, as I have not yet had children.”

AstraZeneca is working with the Medical Oncology Group of Australia (MOGA) and the Therapeutic Goods Administration (TGA) to identify potential solutions, while the PBAC is set to meet with the company this week outside its usual intracycle meeting schedule to determine next steps.

“We understand that any change to medicines can create concerns for clinicians, patients and their families, and we are approaching this transition carefully and responsibly to ensure that patients can continue to receive the treatment they need,” said the company in a statement.

While AstraZeneca has floated the possibility of a limited compassionate access scheme, details remain vague. Critics argue such measures are, at best, a stopgap. Without subsidy, patients could face costs of more than $700 per dose, equating to thousands of dollars annually for a therapy often prescribed for up to a decade.

Switching from Zoladex 3.6 mg to the 10.8 mg dosing will require careful clinical management to ensure appropriate treatment response.

“It may offer some benefits with less frequent injections and lower cost of attendance provided it is covered by the PBS. Transitioning should be possible for those well-established on therapy and particularly if they are also on Tamoxifen,” Professor Boyle told Health Industry Hub. “With patients on aromatase inhibitors, we would need to check that estrogen remains suppressed. For use in fertility preservation, there is more concern.”

For clinicians weighing alternative treatment pathways, Diphereline (triptorelin) may be a viable option for this patient cohort.

“There is data on triptorelin for both uses in breast cancer and we have experience with using it in the SOFT and TEXT trials. It was similarly tolerated and the IM injection is probably on par with the Zoladex subcut which can be quite painful,” explained Professor Boyle. “In NZ there was some experience with generics of triptorelin that were unsatisfactory, so we would welcome the advice of NZ consumers and Pharmac.”

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