Palbociclib Boosts Progression-Free Survival in Triple-Positive Breast Cancer

The survival chances for women with ‘triple-positive’ breast cancer increase significantly with the addition of a drug called palbociclib, which compromises cancer cells’ ability to divide and multiply. 

The international PATINA trial, published in the New England Journal of Medicine in January 2026, involved 518 women with triple-positive breast cancer – cancers which express oestrogen receptors (ER), progesterone receptors (PR) and human epidermal growth factor (HER2) – that had spread, or metastasised, beyond the breast and lymph nodes. 

The standard of care for this type and stage of breast cancer is a combination of endocrine therapy drugs and HER2-directed therapies, such as pertuzumab and trastuzumab.  

The aim of the PATINA trial was to see if there could be additional benefits from adding another drug – palbociclib – to that regimen. Palbociclib inhibits the action of proteins that are critical for cancer cell growth, and previous studies had shown positive effects in women with ER-positive, HER2-negative breast cancer. 

“In terms of targeting the oestrogen receptor, one analogy is that endocrine therapy is akin to Batman and palbociclib is akin to Robin; the sidekick that works together with endocrine therapy to make it better and more effective,” said Professor Elgene Lim, a medical oncologist and researcher at the Garvan Institute of Medical Research in Sydney, who was the lead Australian investigator on the PATINA trial. 

The results were impressive. Women who were treated with the standard oestrogen-suppressing and HER2-targeting therapies achieved an average of 29.1 months without their disease getting any worse, but those who were also given palbociclib achieved an average of 44.3 months without progression. For some women, that meant their disease remained stable but others saw their tumours shrink, in some cases to the point where the cancer was no longer detectable. 

Professor Lim said 44 months without disease worsening was impressive. “This is an undoubtedly a success, and undoubtedly a benefit to these patients, because of that significant improvement in terms of progression-free survival,” he said. “We’ve rarely seen a situation where we’ve had this average duration of progression-free survival in any cancer in the metastatic setting.” 

Around 10 percent of the women in the study were based in Australia and some were Professor Lim’s patients. While the study itself only required five years of palbociclib treatment, around 28 percent of the women in the palbociclib treatment group chose to stay on the treatment. “Many patients of mine are still doing well after five years,” he said.  

Publication: 

Metzger O, Mandrekar S, Goel S, Gligorov J, Lim E, Ciruelos E, Loibl S, Dockter T, Gonzalez Farre S, Francis PA, Lynce F, Lanzillotti J, DuFrane C, Wall A, Strand C, Krop I, Vaz-Luis I, Tripathy D, oi S, Prat A, Goetz M, Escriva-de-Romani S, Porter D, Spoenlein J, Stover DG, Sardesai S, Heudel P, Koehler M, Huang Martlett C, Hoynskyj A, Gopalakrishna P, Gauthier E, Delaloge S, Miller K, Winer EP, Gianni L, Partridge AH, DeMichele A, Carey LA. Palbociclib for Hormone-Receptor-Positive, HER2-Positive Advanced Breast Cancer. New England Journal of Medicine 2026; 394  451-462 DOI: 10.1056/NEJMoa2511218