The Right Medicine

In many cases, oral anticancer therapies have changed the way cancer is treated. Here’s a look at oral anticancer therapy in three cancer types:

Chronic myeloid leukemia (CML)

CML is sometimes called the poster child for oral chemotherapy. Prior to May 2001, treatment options of interferon and bone marrow transplantation were suboptimal, with low cure rates and high complication rates. But then a new era in oral anticancer therapy was ushered in when the Food and Drug Administration (FDA) approved Gleevec (imatinib), a type of tyrosine kinase inhibitor that blocks the protein made by the BCR-ABL oncogene. Similar medications have since been approved that can work when patients develop resistance to Gleevec. Some experts now consider CML a manageable chronic disease. While some patients have successfully stopped taking medication for CML without relapse, the disease generally requires long-term maintenance treatment with oral anticancer therapy, perhaps for a patient’s lifetime. Studies show that adherence decreases over time. Lack of adherence can lead to disease progression, development of medication resistance and, ultimately, risk of death.

Breast cancer

Tamoxifen and aromatase inhibitors are the most common forms of hormone therapy for estrogenreceptor- positive breast cancer. They deprive tumors of the estrogen needed to grow by either blocking estrogen’s effects or blocking estrogen production. Hormone therapy can help prevent recurrences and stop or slow the growth of cancer that has spread. These medications are usually taken in pill form once or twice a day. The optimal length of treatment is still under investigation, but hormone therapy is usually taken for five years, and new research has shown a benefit when taken for 10 years. Tamoxifen, which has been in use for more than 30 years, is in a class of medications known as anti-estrogens or selective estrogen receptor modulators (SERMs). It blocks the effects of estrogen in the body. Aromatase inhibitors, including anastrozole, exemestane and letrozole, inhibit the enzyme aromatase, which is part of the estrogen-production process.

Metastatic cancers

Several types of oral anticancer therapy are available to treat metastatic cancer. For example, Sutent (sunitinib), a tyrosine kinase inhibitor, is used to treat metastatic gastrointestinal stromal tumor, renal cell carcinoma and, most recently, pancreatic neuroendocrine tumors. In approving Sutent for this type of pancreatic tumor, the FDA noted that in a large study the drug extended median time until the cancer spread to just over 10 months, compared with around five months for placebo treatment. In 2011, the FDA approved Zytiga (abiraterone acetate) for treatment of advanced castration-resistant prostate cancer, after a phase 3 clinical trial showed that the median overall survival rate was 14.8 months among patients who received Zytiga and prednisone, and 10.9 months among those who received prednisone and placebo. Nexavar (sorafenib), in a class of medications called multikinase inhibitors, is used to treat advanced renal cell carcinoma and unresectable hepatocellular carcinoma. Like in other oral anticancer therapies, studies showed that it offered a small but significant survival advantage of at least several months.