Pashtoon Kasi, M.D., M.B.B.S.

Every day, Pashtoon Kasi, M.D., M.B.B.S. is inspired by his patients with colorectal cancer to deliver the best, individualized care to meet their unique needs. As an oncologist at Mayo Clinic's campus in Florida, Dr. Kasi is seeing many of the growing number of younger patients – those in their 20’s, 30’s and 40’s – diagnosed with the disease and facing at times years of treatment with a combination of therapies.

While there are many new treatment options available, some patients can experience debilitating side effects from chemotherapy drugs or other medications used to manage their symptoms. These patients may experience ongoing nausea, diarrhea, fatigue and anxiety, all interfering with their daily life.

With support from the Mayo Clinic Center for Individualized Medicine, Dr. Kasi and his team are using pharmacogenomics – how a person’s genes impact their response to medications – to identify the right dose of the available chemotherapy treatments as well as the best symptom management medications most suitable for each patient. Their first pilot study using pharmacogenomics testing revealed that the majority of patients had at least one genetic factor that affected the way they process medications.

"Patients with colorectal cancer are living longer, thanks to new treatment options. However, because patients are living longer, they are often treated with a combination of multiple chemotherapy drugs and other supportive medications, putting them at higher risk for experiencing side effects that can impact their quality of life. By integrating pre-emptive pharmacogenomics testing at the time a patient is diagnosed with colorectal cancer, we are able to tailor their treatments and improve their overall care." - Pashtoon Kasi, M.D., M.B.B.S.

“Patients with colorectal cancer are living longer, thanks to new treatment options. However, because patients are living longer, they are often treated with a combination of multiple chemotherapy drugs and other supportive medications, putting them at higher risk for experiencing side effects that can impact their quality of life. By integrating pre-emptive pharmacogenomics testing at the time a patient is diagnosed with colorectal cancer, we are able to tailor their treatments and improve their overall care,” says Dr. Kasi.

Here’s how Dr. Kasi and his team are putting this approach into action.

Pharmacogenomics – bringing the whole patient into view

At the time a patient is diagnosed with colorectal cancer, Dr. Kasi and his team use DNA collected from a simple cheek swab to conduct pharmacogenomics testing that screens for genetic changes in 23 genes that could impact medication response.

“As a first step, we are focusing on two genes that affect how a patient responds to the most commonly used chemotherapies – irinotecan and 5-Fluorouracil (5-FU) chemotherapy – to help guide dosing and avoid the serious side effects that some patients can experience, such as nausea, diarrhea, mouth sores, low white blood cell counts and extreme fatigue. We are also looking and learning about the 21 other genes associated with a broad range of medications, many which can be used to treat a patient’s symptoms,” says Dr. Kasi.

The pharmacogenomics testing is already making a big difference for some patients. For example, one patient had severe anxiety and depression, despite taking the medication that was prescribed to him to treat his symptoms. Pharmacogenomics testing helped identify why the particular medication was not working for him as intended, revealing that he was metabolizing or processing the medication too quickly.

“After switching to another medication as suggested by the pharmacogenomics testing, this patient finally found relief within weeks and enjoyed a much better quality of life,” says Dr. Kasi. “This approach helps us individualize care by looking at all factors that can affect a patient’s overall health.”

Dr. Kasi and his team, which includes Mayo pharmacist Caren Hughes, Pharm. D., R.Ph., have shown that real-time point of care preemptive comprehensive pharmacogenomics testing can be integrated into practice for cancer patients, using genetic testing that has a fast turnaround time for results at a low cost.

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