On Jennifer van Leeuwen’s 54th birthday, she got news that was far from celebratory. In 2012, she was diagnosed with Stage 4 malignant pleural mesothelioma (MPM), a rare form of lung cancer. It had spread to her abdomen and she was given less than a year to live.

Nearly six years later, the 59-year-old Burlington, mother of three, is doing well. She’s on a second immunotherapy clinical trial at The Princess Margaret. She believes the ground-breaking form of cancer therapy is the reason she is still alive.

“The immunotherapy treatments have allowed me to live way beyond my expectations, and I would say, a lot of the physicians’ expectations,” says Jennifer.

After her diagnosis, Jennifer began chemotherapy and initially responded well. But by 2015, the disease had progressed.

Jennifer and her husband John started looking into new, innovative therapies. They heard of an immunotherapy option called TIL (Tumour-Infiltrating Lymphocyte) transplant through Dr. Marc de Perrot.

“Immunotherapy really seemed like the way to go. To be able to customize a treatment for an individual, it seemed like a great thing,” says Jennifer.

But the treatment was still in its early stages, and it wasn’t an option for Jennifer at that time.

She was instead accepted into a Phase 1 trial of a targeted chemo drug, under the direction of Dr. Lillian Siu, at The Princess Margaret in January 2016.

Even though the tumour in her lung had responded to the drug, Jennifer was developing a large amount of fluid in her abdomen. When side effects proved to be too much to handle, Jennifer had to withdraw from the trial in October.


At around the same time, the TIL treatment was finally made available, and Jennifer received an infusion in February 2017 under the direction of Drs. Pam Ohashi and Marcus Butler.

The procedure involved engineering Jennifer’s cells in a lab to increase the number of good T-cells (important white blood cells) to attack the cancer, then returning them back into her body.

“I believe I was the first mesothelioma patient to receive TILS in North America and possibly the world. It was uncharted territory on all accounts.”

The transplant took a toll on Jennifer’s body, but the fluid in her abdomen was eliminated and the progression in her lungs had slowed down.


Unfortunately, by September 2017, the tumour began to grow again.

Jennifer is now receiving a new immunotherapy checkpoint inhibitor drug that works with the immune system to attack the cancer. Under the direction of Dr. Penny Bradbury, they’re waiting to see if her tumour will respond to the drug.

“You have to be patient and have faith. You will have successes, you’ll have big setbacks, but people learn from the setbacks. If I can pave the way for patients in the future, whether it be in mesothelioma or other cancers, I’m willing to do that,” says Jennifer.

Along the way, Jennifer has relied on her faith and on the support of John and her children. Her two daughters have been inspired by their mother’s journey and have chosen to pursue careers in healthcare to improve outcomes for cancer patients.

Jennifer remains hopeful about a positive outcome. She and John are very appreciative of all the doctors, nurses, friends and family who continue to support them through this journey.

“The Princess Margaret is a fantastic Cancer Centre,” says Jennifer. “I truly believe the immunotherapy program has allowed me to live well beyond the initial estimate of my life expectancy.”

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