Administrative Assistant: Nisa Chaudr
Phone: 416-480-5000, ext. 5847
Email: nisa.chaudhry@sunnybrook.ca

Education:

• MD, 1979, University of Iceland, Iceland
• FRCPS(C), 1987, Certification in Internal Medicine, Royal College of Physicians and Surgeons, Canada
• FRCPS(C), 1988, Certification in Medical Oncology, Royal College of Physicians and Surgeons, Canada

Appointments and Affiliations:

• Senior scientist, clinical integrative biology - Odette cancer research program, Sunnybrook Research Institute
• Associate professor, faculty of medicine, University of Toronto

Research Foci:

• The potential clinical applications of chronobiology and chronopharmacology in oncology
• Kidney cancer therapy

Research Summary:

Dr. Bjarnason's research focuses on the potential clinical applications of chronobiology and chronopharmacology in oncology. Most physiological and metabolic processes in the body are ordered in time (have a circadian rhythm). Therefore, the time of day a drug is delivered impacts on how it is handled in the body. Several clinical trials have now confirmed that chemotherapy timing can impact on the side effects profile, and in some cases improve activity. Based on his data looking at cell cycle progression in oral mucosa, Dr. Bjarnason has shown that the timing of radiotherapy can impact the severity of oral mucositis in patients with head and neck cancer.

The new drugs that are being introduced for cancer are aimed at molecular targets (including angiogenesis) that are much more specific than those of conventional chemotherapy. The expression of many of these molecular targets varies significantly through the 24-hour day. Dr. Bjarnason is working to define the 24-hour variation of these new cancer therapy targets both at the gene level and protein level in human tissue to allow for the design of intelligent clinical trials to optimize the effect and minimize the toxicity of these drugs. Studies are ongoing/planned to look at the timing of these targeted drugs.

The genetic control of the circadian rhythms has recently been defined. The "clock genes" also control the circadian rhythm of cell division, cell death and angiogenesis. These processes are abnormal in human cancer. He is currently studying the expression of clock genes in cancer tissue, looking for both mutations and an abnormal circadian variation. When the sleep/activity rhythm is disturbed in animals and humans, cancer grows faster. Dr. Bjarnason is conducting clinical trials using melatonin to normalize the circadian rhythm in patients with breast cancer and colorectal cancer.

Furthermore, Dr. Bjarnason does clinical trials in patients with kidney cancer, both with regard to chronotherapy and drug discovery.

Selected Publications:

See current publications list at PubMed.

Book chapters (not in PubMed):

1. Hrushesky WJM, Bjarnason GA, Vyzula R. Circadian Cancer Chronotherapy. In: Cvitkovic E, Droz JP, Armand JP, Khoury S, ed. Handbook of chemotherapy in clinical oncology. Jersey: Scientific Communication International Ltd., 1993:109-119.
2. Bjarnason GA, Hrushesky WJM: Preclinical trials of cancer chronotherapy. In: Circadian Cancer Therapy. (Hrushesky WJM, ed.) Boca Raton. CRC press. 1994. 211-239.
3. Bjarnason GA, Hrushesky WJM: Cancer Chronotherapy. In: Circadian Cancer Therapy. (Hrushesky WJM, ed.) Boca Raton. CRC press. 1994. 241-263.
4. Vyzula R, Bjarnason GA, Hrushesky WJM. Chronopharmacology and avoidance of anticancer drug toxicity. In: Sweetenham JW, Williams CJ, ed. Supportive Care of the cancer patient. London: Edward Arnold Publishers, 1996:74-86.
5. Bjarnason GA, Giacchetti S, Mormont C, Levi F. Aspects cliniques de la chronothérapie du cancer. In: Chronopharmacologie: rythmes biologiques et médicaments (Labrecque G, Sirois-Labrecque M eds.); Les Presses de l'Université de Montréal, Montréal, pp 346-374, 2002.