The stakes could hardly be higher. Breast cancer remains the second most common malignancy among women worldwide, with roughly 2.3 million new cases diagnosed in 2022 according to global cancer statistics. In China alone, an estimated 357,000 women were diagnosed and 75,000 died from the disease that year. Between 20 and 30 percent of these tumors carry amplification of the human epidermal growth factor receptor 2 gene, a molecular driver that fuels aggressive tumor initiation, invasion, and proliferation. Thanks to modern anti-HER-2 therapies, patients whose tumors overexpress this protein now fare far better than they did two decades ago, but the choice of chemotherapy backbone paired with those targeted agents still matters enormously.

Paclitaxel has long been a cornerstone of breast cancer chemotherapy. As a taxane, it works by stabilizing microtubules, inhibiting the depolymerization of tubulin and promoting polymerization, thereby arresting mitosis and suppressing tumor cell proliferation. Yet conventional solvent-based formulations carry a well-known pharmacological liability: they rely on polyoxyethylated castor oil and anhydrous ethanol as vehicles. The castor oil derivative can activate mast cells to release histamine, triggering severe hypersensitivity reactions that require routine corticosteroid premedication. Worse, the solvent forms micellar complexes with paclitaxel in the bloodstream, limiting tissue penetration and potentially blunting antitumor efficacy. Liposomal encapsulation within phosphatidylcholine sidesteps both problems, enhancing drug stability, prolonging retention and effective half-life in the body, and eliminating solvent-related toxicities.

Despite landmark trials such as H0648g, M77001, and CLEOPATRA establishing taxane plus anti-HER-2 therapy as the standard first-line approach, robust evidence on paclitaxel liposome specifically had been lacking. To close that gap, investigators turned to the National Cancer Center Oncology Information Database, the largest oncology database in China, spanning more than 2,000 hospitals across 31 provinces and approximately 22 million cancer patients since 2013, with mortality data integrated from the national death registry. From this resource, they identified 526 patients with unresectable locally advanced or metastatic HER-2-positive breast cancer who received paclitaxel liposome combined with anti-HER-2 agents as first-line salvage therapy between January 2013 and December 2022.

The cohort, with a median age of 53 years and 56.3 percent hormone receptor-positive disease, reflects the messiness of real-world oncology. Just over half of patients, 53.2 percent, received paclitaxel liposome plus trastuzumab, the workhorse monoclonal antibody that binds the HER-2 receptor’s extracellular domain. Another 32.1 percent received triple therapy with trastuzumab and pertuzumab, which blocks receptor dimerization and delivers dual blockade of HER-2 signaling. A further 11 percent combined trastuzumab with small-molecule tyrosine kinase inhibitors. Before treatment, a third of patients had bone metastases, roughly 30 percent had lung metastases, and 23 percent had liver involvement, while 58.6 percent had disease confined to a single organ. Notably, 75.9 percent had never received a taxane in the earlier treatment setting, making them ideal candidates for first-line salvage therapy with the liposomal agent.

The efficacy numbers were striking. After a median follow-up of 856 days, the overall median real-world progression-free survival reached 22.1 months, with one-, two-, three-, and five-year progression-free rates of 72.1, 46.7, 34.0, and 21.0 percent respectively. Median overall survival extended to 57.9 months, an exceptional figure for metastatic disease, with 97.2 percent of patients alive at one year and nearly half surviving five years. The objective response rate stood at 55.9 percent, and disease control, encompassing complete responses, partial responses, and stable disease, reached a remarkable 94.7 percent. Hormone receptor-positive patients fared best, with median progression-free survival of 24.5 months and overall survival of 60.5 months, compared with 17.7 and 53.5 months in hormone receptor-negative patients, evidence that the regimen delivers substantial benefit regardless of hormone receptor status.

Digging deeper into treatment combinations revealed clinically meaningful differences. Patients on paclitaxel liposome plus trastuzumab alone achieved a median progression-free survival of 17.2 months, while those receiving dual blockade with pertuzumab reached 33.3 months, an unsurprising but welcome confirmation that blocking HER-2 through two independent mechanisms deepens disease control. The kinase inhibitor combination produced 21.9 months. Interestingly, median overall survival was numerically longer in the trastuzumab-only group, 59.1 versus 49.9 months for dual blockade, a paradox the authors attribute to confounding by indication: pertuzumab was not reimbursed nationally during much of the study period, so clinicians reserved the intensive dual-blockade regimen for patients with higher tumor burdens and more aggressive disease. Multivariable analysis confirmed that dual blockade was itself an independent protective factor, cutting the hazard of progression roughly in half, while having two or more metastatic sites doubled the risk of both progression and death.

Safety data reinforced the formulation’s pharmacological advantage. Myelosuppression, the expected paclitaxel-related bone marrow suppression, occurred in 34.8 percent of patients, and gastrointestinal reactions in 18.4 percent, while hepatic dysfunction and neurotoxicity each remained below 5 percent. No new safety signals emerged. Critically, the liposomal delivery system eliminated the hypersensitivity risk that defines solvent-based paclitaxel, sparing patients the steroid premedication and infusion reactions that complicate conventional taxane administration. Treatment adherence was correspondingly strong: 81.4 percent of patients completed therapy at full dose, 64.4 percent finished the planned course, and another 14.3 percent continued the drug as maintenance, with only 2.3 percent discontinuing due to intolerance.

The authors are candid about the limitations inherent to retrospective, registry-based research. Physician-determined progression assessments were not subjected to independent central imaging review, performance status was unrecorded for 42.8 percent of patients, incomplete adverse event documentation prevented detailed toxicity grading, and the database did not capture granular HER-2 expression patterns or paired pathology from primary and metastatic lesions. Regional differences in response assessment may also explain why the objective response rate, while solid, trails that of some randomized trials, a discrepancy partly explained by the high proportion of bone-only metastases, which often manifest as stable disease rather than measurable shrinkage under RECIST 1.1 criteria. Still, the overall picture aligns closely with the CLEOPATRA and PHILA trials, and the study stands as the largest real-world analysis of first-line treatment for HER-2-positive advanced breast cancer in China to date, suggesting that paclitaxel liposome deserves a firm place alongside, and perhaps in preference to, solvent-based taxanes in global treatment guidelines.

Subject of Research: Paclitaxel liposome combined with anti-HER-2 targeted drugs as first-line therapy for recurrent or metastatic HER-2-positive breast cancer in a real-world setting.

Article Title: Paclitaxel liposome with anti–HER-2 drugs as first-line therapy for recurrent/metastatic HER-2–positive breast cancer: a real-world study

Article References: Paclitaxel liposome with anti–HER-2 drugs as first-line therapy for recurrent/metastatic HER-2–positive breast cancer: a real-world study. (n.d.). https://doi.org/10.1007/s44178-026-00283-8

Image Credits: AI Generated

DOI: 10.1007/s44178-026-00283-8

Keywords: paclitaxel liposome, HER-2-positive breast cancer, trastuzumab, pertuzumab, real-world study, progression-free survival, overall survival, targeted therapy, chemotherapy, metastatic breast cancer, drug delivery, oncology