Herb Hunter

One of the many distasteful aspects of cancer treatment is the time spent sitting at a hospital or clinic receiving long regimens of intravenous chemotherapy. While attempts have been made to minimize side effects and simplify treatments, most standard chemotherapy regimens still require intravenous therapy. Researchers have long been searching for a “magic pill” that patients could take once or twice a day as an alternative to intravenous chemotherapy, and while that research continues, some chemotherapy is currently available in oral pill form, and today I will review one of the most recently approved oral medications.

There are many theories concerning the origin and growth of cancer cells, and targeted therapy is a process that uses specific medications to “target” suspicious areas in and around diseased cells. For example, structures called Epidermal Growth Factor Receptors (EGFRs) are located on the surface of many types of cancer cells. Epidermal Growth Factor (EGF) is a protein common throughout our body. When EGF’s are just floating around our bloodstream, looking for action on a Friday night, (Or anytime, for that matter.) they will find the “action” on an EGFR. When the protein binds to the receptor, an enzyme called Tyrosine Kinase (TK) inside the cell triggers chemical signals to make the cell grow and divide. If this process could be inhibited, cancer cells would be prevented from duplicating.

Inhibiting this receptor is a key to targeted therapy, and as the name suggests, cancer cells are the ones being targeted for inhibition, while at the same time causing little disruption to the surrounding normal healthy cells. An example of an oral medication used for just such a targeted therapy is our focus for today. The medication is called Tarceva.

Tarceva (erlotinib) is an oral tablet that is in a group of drugs known as epidermal growth factor receptor inhibitors. Further, it specifically acts as a tyrosine kinase inhibitor, attaching itself to the TK enzyme and preventing the EGFR from activation. In this way, tumors are prevented from growing.

Tarceva is used for non-small cell lung cancers and pancreatic cancers that have not responded to at least one course of chemotherapy, and may be effective against ovarian and head and neck cancers, as well.

Tarceva is available as a 100 mg. and a 150 mg. tablet, is taken once a day in the morning, and should be taken on an empty stomach, approximately one hour before or two hours after a meal. Side effects include rash, diarrhea, nausea, and fatigue, but most of these side effects may be controlled with medication or go away over time.

However, before we declare cancer to be cured by this “magic pill,” we need to remind ourselves of just how virulent cancer cells are by nature. A good way to envision this process is to compare chemotherapy medications to antibiotics. As antibiotics are targeted at constantly mutating bacteria, chemotherapy is targeted at mutating cells, that become resistant with each mutation.

An unfortunate inherent problem with EGFR directed treatments, such as Tarceva, seems to be resistance. It appears that after an eight to twelve month period, some cancer cells may become resistant to the treatment. These clever cancer cells seem to be able to use a mutated Insulin-like Growth Factor 1 (IGF-1) receptor that resembles a tyrosine kinase receptor, to act as an EGFR. This allows the signal for growth and duplication to be transmitted, and the tumor will once again be able to grow, even in the presence of Tarceva.

As you might have guessed, research is currently underway to develop a IGF-1R inhibitor to theoretically use after Tarceva is no longer effective.

Further, as you might have guessed as well, all of this research is expensive, and Tarceva isn’t exactly cheap. A thirty-day supply, before insurance, could cost as much as four to five thousand dollars. Is it any wonder affordable health insurance has made its way to number one or two on the list of Presidential debate topics as the campaigns move into their final stretch and the fall elections?

A pill to cure cancer has been the dream of medical researchers for many years, and while Tarceva may be effective on some cancers for a designated period of time, it does not seem to be the “magic pill.” Perhaps, as research continues, we will see that pill at some point in our lifetime. Until then, an ounce of prevention is worth several hundred pounds of cure in the case of malignancies, so be sure to follow the American Cancer Society’s recommendations to lower your risk factors. I may not be able to predict when medical science will find the cure for cancer, but I am certainly able to predict, with absolute confidence, that those recommendations for lowering cancer risk factors will be featured in a future edition of “The Pill Box.” Don’t miss it!

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