The oral tyrosine kinase inhibitor neratinib (Nerlynx – Puma Biotechnology) has been approved by the FDA for use in combination with capecitabine (Xeloda, and generics) for treatment of advanced or metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer in adults who received ≥2 prior anti-HER2-based regimens for metastatic disease. It was previously approved for use as monotherapy for extended adjuvant treatment of adults with early-stage, HER2-positive breast cancer following adjuvant trastuzumab (Herceptin)-based therapy. HER2 is overexpressed in about 20% of breast cancers. Up to 30% of early-stage, HER2-positive breast cancer cases treated with trastuzumab-based adjuvant therapy recur. Neratinib is the only HER2-directed small molecule approved for treatment of early-stage and metastatic HER2-postive breast cancer.

The oral cyclin-dependent kinase (CDK) 4/6 inhibitor abemaciclib (Verzenio – Lilly), which was approved by the FDA in 2017 for treatment of hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer, has now been approved for use in combination with endocrine therapy (tamoxifen or an aromatase inhibitor) for adjuvant treatment of patients with HR-positive, HER2-negative, node-positive, early breast cancer at high risk of recurrence and a Ki-67 score ≥20%.

The FDA has approved a fixed-dose combination of pertuzumab, trastuzumab, and hyaluronidase (Phesgo – Genentech) for use in combination with chemotherapy for neoadjuvant (preoperative) treatment of human epidermal growth factor receptor 2 (HER2)-positive, locally advanced, inflammatory, or early-stage breast cancer, or for adjuvant treatment of patients with HER2-positive early breast cancer at high risk of recurrence, or with docetaxel for treatment of those with HER2-positive metastatic breast cancer who have not received anti-HER2 therapy or chemotherapy for metastatic disease. Phesgo is the first combination that contains pertuzumab and trastuzumab for SC administration. IV pertuzumab (Perjeta) and IV and SC trastuzumab (Herceptin, and others) have been available for years for treatment of HER-2 positive breast cancer.

The FDA has approved two new drugs for treatment of previously-treated unresectable or metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer: fam-trastuzumab deruxtecannxki (Enhertu – Daiichi-Sankyo/AstraZeneca), an IV HER2-directed monoclonal antibody linked to the topoisomerase I inhibitor DXd, and tucatinib (Tukysa – Seagen), an oral tyrosine kinase inhibitor.

The FDA has approved the oral tyrosine kinase inhibitor neratinib (Nerlynx – Puma Biotechnology) for extended adjuvant treatment of adults with early-stage, human epidermal growth factor receptor 2 (HER2)-positive breast cancer, following adjuvant trastuzumab (Herceptin)-based therapy. HER2 is overexpressed in about 20% of breast cancers. Up to 30% of early-stage, HER2-positive breast cancer cases treated with trastuzumab-based adjuvant therapy recur.

The FDA has approved abemaciclib (Verzenio – Lilly), an oral cyclin-dependent kinase (CDK) 4/6 inhibitor, for treatment of hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer. Abemaciclib is the third CDK 4/6 inhibitor to be approved in the US for this indication.

The FDA has approved the neoadjuvant (preoperative) use of pertuzumab (Perjeta – Genentech) in combination with trastuzumab (Herceptin) and docetaxel (Taxotere, and generics) for treatment of locally advanced, inflammatory, or early-stage HER2 (human epidermal growth factor receptor 2)-positive breast cancer patients with tumors >2 cm in diameter or node-positive disease. Pertuzumab in combination with trastuzumab and docetaxel was approved earlier for treatment of HER2-positive metastatic breast cancer. Pertuzumab is the first drug to be approved for neoadjuvant treatment of breast cancer.

Pertuzumab (Perjeta – Roche/Genentech), a humanized monoclonal antibody, has been approved by the FDA for use in combination with trastuzumab (Herceptin) and docetaxel (Taxotere, and others) for first-line treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer.

The FDA has approved the use of the 5α-reductase inhibitor dutasteride (Avodart - GlaxoSmithKline) together with the alpha₁-blocker tamsulosin (Flomax - Boehringer Ingelheim) for treatment of benign prostatic hyperplasia (BPH). Use of an alpha1-blocker with a 5α-reductase inhibitor has been a common practice for years, but FDA approval of a particular combination permits the manufacturers to add an indication for it in both package inserts, recommend dosage for combination use, and advertise the benefits of using the 2 drugs together.

Bevacizumab (Avastin - Genentech) is a recombinant humanized monoclonal antibody that binds to vascular endothelial growth factor and prevents it from binding to receptors on endothelial cells, inhibiting formation of new blood vessels. Previously approved by the FDA for use in combination regimens for first-line treatment of metastatic colon cancer and metastatic non-small cell lung cancer, and used off-label for treatment of agerelated macular degeneration, it has now also been approved by the FDA for use in combination with paclitaxel (Taxol, and others) for first-line treatment of HER2-negative metastatic breast cancer.

In addition to surgery and radiation therapy, a variety of drugs are used both singly and in combination to treat breast cancer. This article summarizes the principles of adjuvant therapy and treatment for metastatic disease. A summary of individual drugs and their adverse effects begins on page 3.

Trastuzumab (Herceptin - Genentech), a recombinant 'humanized' monoclonal antibody (rhuMAb) that binds to a protein encoded by the oncogene HER2, and capecitabine (ka pe site' a been; Xeloda - Roche), an oral pro-drug for 5-fluorouracil, have been approved by the FDA for treatment of metastatic breast cancer.