Inclusion criteria:
Women aged 18-75 years
Metastatic breast cancer (Metastasis to intraperitoneal solid organs, lungs, pleura, or multiple bones) Based on histological, cytological and imaging results.
HER2+ (immunohistochemistry 3+, HER2 gene amplification in fluorescence in situ hybridization positive or positive HER2 result in Chromogenic in situ hybridization).
Patients with measurable disease based on Response Evaluation Criteria in Solid Tumors, version 1.1, (the minimum size of a measurable lesion at baseline should be no less than double the slice thickness (when CT scans have slice thickness greater than 5 mm, the minimum size for a measurable lesion should be twice the slice thickness)).
Life expectancy of more than 12 weeks based on a physician or treatment team estimate.
Acceptable clinical test results at the beginning of the study based on the normal range of the reporting laboratory
An Eastern Cooperative Oncology Group performance status of 0–2
All the patients provided written informed consent.
Exclusion criteria:
History of type 1 allergic/anaphylactic infusion reactions to any component of the PADYNEX formulation
History of treatment with trastuzumab-emtansine
Patients with locally advanced breast cancer and non metastatic
History of second non-breast cancer in last 5 year
Patients with brain metastasis
Serious concurrent disease (chronic kidney disease stage 4,5, hepatic impairment child pugh class c, bronchiectasis, severe chronic obstructive pulmonary disease, severe asthma, pulmonary fibrosis)
Peripheral neuropathy of grade 3 or worse (as per National Cancer Institute Common Terminology Criteria for Adverse Events [NCI CTCAE] version 5.0)
Left ventricular ejection fraction lower than 50% (as measured by echocardiography) within previous 3 months, myocardial infarction or congestive heart failure within previous 6 months, high-risk uncontrolled arrhythmias; clinically significant valvular disease; concomitant medication for the treatment of unstable angina, uncontrolled blood pressure (higher than 200/100 mmHg), severe electrical conduction defect (having a pacemaker or electrocardiogram diagnosis) or Any other significant heart disease.
Blood disorders such as baseline absolute neutrophil count lower or equal to 1,500 per microliter or platelet count lower or equal to 100,000 per microliter.
Alanine aminotransferase/ aspartate aminotransferase higher or equal to 2.5 upper limit of normal.
Pregnancy, breast-feeding, and women of childbearing potential not using contraception.