A breast cancer drug - which keeps the disease stable for up to four times longer than the previous treatment - will be publicly funded from next month, along with other medicines to treat lung cancer and two potentially deadly lung conditions.

From 1 January 2025 Pharmac will fund:

- osimertinib (branded as Tagrisso) for people with a type of advanced non-small cell lung cancer

- trastuzumab deruxtecan (branded as Enhertu) for people with HER2-positive metastatic breast cancer

- palivizumab (branded as Synagis) to prevent RSV in high-risk babies and young children

- budesonide, glycopyrronium and formoterol triple inhaler (branded as Breztri Aerosphere) for people with chronic obstructive pulmonary disease (COPD).

Director of pharmaceuticals Geraldine MacGibbon said about 120 people with HER2-positive metastatic breast cancer would benefit from trastuzumab deruxtecan in the first year of funding.

One in nine New Zealand women get breast cancer in their lifetimes, and around 16 percent of metastatic breast cancers are classified as HER2-positive.

"Oncologists, people with cancer and their community supporting them have described trastuzumab deruxtecan as a huge advance for HER2-positive breast cancer, so we're pleased to be able to fund it," MacGibbon said.

Breast Cancer Foundation chief executive Ah-Leen Rayner said the announcement would bring "immense relief" to many.

"Enhertu really is a remarkable drug - rarely have we seen doctors so excited by the potential of a new medicine. Having Enhertu funded will mean women with HER2-positive advanced cancer will get the chance to live longer, happier and healthier lives without the financial strain of figuring out how to pay for it themselves - or go without.

Breast Cancer Aotearoa Coalition chair Libby Burgess said it was a "breakthrough medicine".

"We're delighted to see this vital medicine funded given the outstanding results from clinical trials showing that Enhertu keeps the cancer stable for four times as long as the previous best treatment and increases length of life. The decision to fund trastuzumab deruxtecan will enable women and their families to get on with their lives."

Pharmac estimated about 200 people with lung cancer would benefit from osimertinib in the first year of funding.

Lung Cancer Foundation head Philip Hope said the announcement met the greatest treatment need right now.

"Osimertinib is the gold standard for this type of lung cancer and it will be life changing for patients and their families."

Palivizumab was a monthly injection that helped protect babies and young children from RSV (respiratory syncytial virus), and was proven to reduce hospitalisation rates for at-risk babies.

MacGibbon said Pharmac expected about 830 babies and young children to benefit each year.

"Funding this medicine helped to reduce hospitalisations from RSV in 2022 and 2023, and had a significant impact on the health system, in particular neonatal intensive care units."

Meanwhile, Pharmac's decision to fund the budesonide, glycopyrronium and formoterol aerosol inhaler is expected to help 5000 New Zealanders with COPD in the first year of funding, rising to 16,000 people after five years.

Chronic obstructive pulmonary disease - which causes breathing problems - is the fourth leading cause of death in New Zealand behind cancer, heart disease and stroke.

MacGibbon said the inhaler would help ease symptoms and quality of life.

In June, the government boosted Pharmac's budget by an extra $604m over four years in order to meet National's pre-election promise to fund more cancer drugs.

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