Stem cells: saving lives by building a new immune system

This miracle of modern medicine is the centrepiece of Ahmad’s program. And although he is not one to brag, he is rightfully proud of the brilliant results his program has achieved. 

In December 2025, the U.S. Center for International Blood & Marrow Transplant Research (CIBMTR) awarded the program its highest rating, a +1 score, for its 87-per-cent one-year survival rate following an allogeneic stem cell transplantation. Among the 204 centres assessed worldwide, only nine achieved this rating.

“This ranking is truly exceptional,” said hematologist Claude Perreault, who founded the bone marrow transplantation unit—now known as the hematopoietic stem cell transplant unit—at HMR and practiced there until 2018.

“This is one of the few fields where quality of care is compared at the international level on the basis of a rigorous analysis that adjusts for confounding factors," said Perreault, now a professor in UdeM's Faculty of Medicine and head of the immunobiology lab at its Institute for Research in Immunology and Cancer (IRIC).

"The fact that HMR exceeded expectations and is the only centre outside the U.S. to achieve this rating speaks volumes about its excellence,” he said.

While the transplant procedure itself lasts barely an hour, everything hinges on preparation and follow-up. And as Ahmad pointed out, it requires a multidisciplinary team to coordinate care at every stage.

Clinicians begin by assessing the patient, securing a compatible donor and tailoring the intensity of the chemotherapy or radiation used to prepare the body for transplant. The actual transplantation is then precisely managed to guarantee safe and successful transfer of the stem cells. The final, vital step is comprehensive follow-up to control infections and manage rejection risks during the patient’s recovery.

Hematologist Sandra Cohen, Ahmad’s colleague and a cord blood transplant specialist, attributes the program’s success to continuity of care—the fact that transplant physicians follow their patients from start to finish.

“Our expertise enables us to anticipate complications rather than simply react to them,” said Cohen, who is also a clinician-researcher and associate clinical professor in UdeM's Faculty of Medicine.

In Quebec, three hospitals perform allogeneic stem cell transplantation: HMR, the McGill University Health Centre and the CHU de Québec. HMR stands out for its high clinical volume, performing roughly half of the province’s adult allogeneic transplants. On both the Canadian and international stages, HMR ranks among an elite group of highly specialized centres of excellence.

This enviable reputation is rooted in over 45 years of clinical expertise and research, a legacy that began with Perreault in 1980.

“My interest in this approach began during my residency at HMR, when I discovered the work of American physician E. Donnall Thomas, a pioneer in bone marrow transplantation and a Nobel Prize laureate,” Perreault recalled. 

The hematologist went on to establish the hospital’s bone marrow transplant unit. His first patient, treated for bone marrow failure, is still alive today. So is his second, who was treated for acute leukemia. At the time, stem cell transplantation was an invasive and risky procedure; one in three patients died from complications.

“Patients had to undergo highly toxic total body irradiation,” Perreault recalled. “They had to spend almost two months in the hospital, and they were vulnerable to infection because we didn’t have effective antivirals.”

Practices have improved significantly over the past four decades: preparatory treatments are much less toxic, infections are better controlled and supportive care is more effective.

Access to donors has also improved significantly—nearly 90 per cent of allogeneic stem cell transplants now come from unrelated donors found through international registries. Combined with highly precise compatibility techniques, these advancements have driven a one-per-cent annual increase in the survival rate, which now stands at nearly 90 per cent.

Testimonials from transplant recipients

• Read the testimonial of Canadian federal cabinet minister Dominic LeBlanc, who received a stem cell transplant in 2019, and the testimonial of Mai Duong, who received a stem cell transplant in 2014.

Another key figure in the program’s success is Jean Roy, a hematologist specializing in stem-cell transplantation. He is a clinician-researcher at the HMR Research Centre and a professor in UdeM's Faculty of Medicine. Upon joining HMR in 1998, after completing a fellowship at the University of Minnesota’s world-leading transplant centre, Roy set out to restructure and modernize HMR’s stem-cell transplantation and cell-therapy program.

At the same time, he made clinical research a priority, establishing a sustainable infrastructure through three philanthropic research chairs, for leukemia, multiple myeloma and stem cell transplantation.

“Clinical research is the natural extension of clinical practice,” said Roy. “It makes the field more rigorous, stimulates innovation and improves quality of care. Ultimately, all patients benefit.” 

Building on its combination of rigorous clinical practice and active clinical research, HMR established the Fellowship in Hematopoietic Stem Cell Transplantation and Cellular Therapy, which received formal academic recognition from UdeM in 2009.

Dr. Sylvie Lachance, the program’s former director, played a key role in establishing its international reputation by securing formal recognition for the Hematopoietic Stem Cell Transplantation and Cellular Therapy subspecialty from the Royal College of Physicians and Surgeons of Canada. This has bolstered the program’s appeal and supported the training of the next generation of specialists.

“The residents and fellows who train here see firsthand what a high-level academic group looks like,” said Roy. “The ‘brain power’ of our team is on par with that of the best centres in the U.S., Canada and Europe, and our clinical expertise and quality of care are second to none.”

Testimonials from IHOT fellows

• Read the testimonial of Yasmina Serroukh and the testimonial of Omar Eduardo Fernandez Vargas, both fellows.

While allogeneic stem-cell transplantation is a complex procedure not suitable for all cancers, it has transformed cancer treatment by demonstrating that it is the immune cells from the donor that eventually eliminate cancer cells in the recipient, not the “preparatory” chemotherapy and radiation treatment.

“We are essentially transplanting an immune system, whose cells then attack the remaining cancer in the recipient,” explained Ahmad.

This breakthrough laid the foundation for the broader field of cell therapy, bridging the gap between complex stem-cell transplantation and modern, more accessible, targeted immunotherapies such as CAR-T. The concept is innovative, effectively creating a ‘living drug’: T cells are harvested from the patient, genetically modified in the lab and then re-injected into the patient. These reprogrammed cells directly target cancer cells with rapid effect.

According to Ahmad, cell therapy is fast becoming one of the “pillars of cancer treatment,” alongside surgery, chemotherapy and radiation. It is already being used successfully to treat certain leukemias, lymphomas and myelomas.

And this is just the beginning: preliminary results suggest it could also be effective against autoimmune diseases, including lupus, multiple sclerosis and rheumatoid arthritis. “Patients with very severe forms of these diseases have shown dramatic responses,” Ahmad noted.

Now, HMR is conducting clinical trials to evaluate an allogeneic form of CAR-T cell therapy—using cells from healthy donors rather than the patient—to treat severe, refractory autoimmune diseases. It is an ‘off-the-shelf’ approach that Ahmad believes will significantly accelerate access to treatment.

In a similar vein, research by IRIC researchers Guy Sauvageau and Anne Marinier led to the discovery of UM171, a molecule that enhances the efficacy of stem-cell transplantation for blood cancer patients.

Evaluated for use in humans for the first time at HMR, UM171 is now undergoing clinical trials led by Cohen. “The molecule has already been approved in Europe, which attests to its strong potential,” she said.

For Ahmad, these advances demonstrate the strength of the HMR model, which seamlessly integrates research and clinical practice.

“We’re witnessing national firsts right here at Maisonneuve-Rosemont Hospital,” he said. “HMR is truly a gem, driven by passionate teams in every specialty. Our +1 rating is a testament to the hard work of our entire staff—it’s a success that belongs to everyone.”

• More than 200 cell therapy procedures performed every year, including 100 allogeneic stem-cell transplants
• 90 per cent of adult stem-cell transplants are to treat blood cancers
• First internationally certified stem-cell transplantation centre in Quebec (2008), and the only one authorized to genetically engineer stem cells for clinical purposes