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"There are many pathways that exist intracellularly that can influence growth in spite of receptor blockade at the entry site of cancer cells," explains Sharon Wilks, M.D., FACP. "There may be some mechanisms that work in a direct path like an assembly line, and then there may be alternate paths that growth signals will take that may lead to failure of cell death and resilience of tumor cell survival. The complexity of tumor growth not only relies upon receptor activation/inactivation and intracellular pathways, but also on the microenvironment, including the bone environment, vascular growth patterns, the immune system and a multitude of other factors that promote tumor survival." As researchers learn more about the complexities of cancer growth, they can apply their newfound knowledge to create treatments that may ultimately cure cancer — but only through clinical testing can these new measures be proven effective. CCCST often has 10 to 15 breast cancer trials open at any given time. "Currently, depending upon the disease presentation, we have a clinical trial for almost every breast cancer type and breast cancer stage," Wilks notes. However, the practice tries to keep the trial lengths relatively short — rang- ing from several months to a year — in order to ensure the data's accuracy. "With trials that drag out over long periods of time, so many factors change," says Allyson Harroff, M.D. "The field of oncology moves so quickly that, over four or five years, standards of care may have dramatically changed, and the data may not be valid or useful." CCCST is currently involved in several trials that implement targeted therapies to control cancer. Particularly promising are the practice's trials target- ing patients with HER2 breast cancer. "Research in this type of breast cancer is moving very quickly," Dr. Harroff says, noting that patients with HER2/ neu-positive cancer tend to have very aggressive forms of the disease. One of these trials uses everolimus, a pill with minimal side effects, to treat patients who have acquired resistance to Herceptin. "With the use of everolimus, which bypasses the resistance to Herceptin inhibition of the HER2 signal, the tumor cells become sensit ive to Herceptin again," Dr. Wilks explains. "If our Phase III study shows value, this will be an extraordinary move in improving the treatment of aggressive and lethal cancers." Another promising treatment for HER2/neu-positive breast cancer is trastuzumab-DM1 (TDM-1). CCCST is currently conducting the only TDM-1 study for adjuvant use in South Texas, as well as a TDM-1 study for metastatic HER2/neu disease. Other clinical trials that CCCST is proud to be part of include a trial examining the use of dasatinib — a form of chemotherapy currently approved for patients with chronic myelogenous leukemia — in treating breast cancer patients with estrogen receptor-positive tumors that seem to be resistant to anti-estrogen therapy. "It appears that dasatinib blocks Src pathways that are known to induce resistance in estrogen receptor-positive pathways," Dr. Wilks notes. The practice is also currently partici- pating in a Phase III study examining potential uses for denosumab, a drug known to be a RANK ligand inhibitor. "Osteoporosis remains a big prob- lem for women with breast cancer," Dr. Wilks explains. "Though this drug appears to work on the bone tree, there are observations that it may also prevent tumor growth, so the aim of this study is to look at prevention of bone fractures and to determine if there are fewer breast cancer relapses in patients who receive this drug." Though every trial has inclusion and exclusion criteria, and subjects must have good performance status to participate, patients with an interest in research are often the most excited about the practice's wide variety of available clinical trials. Dr. Harroff also notes that patients with an atypical form of breast cancer, as well as young patients, may benefit the most from the trials. "That way, we can gather more information about them rather than lumping them in with all breast cancer patients," she explains. Dr. Harroff cites patients with triple- negative breast cancer as a specific subgroup that tends to find clinical trials particularly beneficial. Triple-negative breast cancer, which refers to an absence of receptors for estrogen, pro- gesterone and HER2/neu, metastasizes quickly and is frequently unreceptive to traditional chemotherapy drugs. "It's very difficult to treat, but some- times, through clinical trials, we have treatment options that are effective but are otherwise not available," Dr. Harroff explains. Today, CCCST is one of the only sites in South Texas that offers a trial for patients with recurrent triple- negative disease, testing a drug called BSI-201 (iniparib). Patients who participate in the clini- cal trials offered by CCCST tend to be highly satisfied with their experiences. "The patient has to be very motivated to do a trial, so those who are motivated to participate in an initial trial are often motivated to continue to participate," Dr. Harroff says. "They feel like they personally get enough out of the experi- ence to participate in multiple trials." For more information about CCCST's extensive clinical trial program, please visit www.CancerCareSouthTexas.com. ■ MDNEWS.COM ■ MD NEWS San Antonio | 21