As a toddler undergoing treatment at McMaster Children’s Hospital in Hamilton, Ont., Caroline Diorio, MD, couldn’t grasp what the nice doctors scurrying in and out of her room were doing. She just knew they were taking care of her.
Dr. Diorio had pediatric immune thrombocytopenia (ITP), a type of platelet disorder in which the immune system attacks blood platelets for usually unknown reasons.
Dr. Caroline Diorio
“I remember very much how worried my parents were,” recalled Dr. Diorio, now a hematologist-oncologist at Children’s Hospital of Philadelphia. “And I remember how the tone of the doctor’s voice and the way the doctors communicated provided so much reassurance to my parents.”
Dr. Diorio’s ITP resolved within a few years, but her experience left a lasting impression.
“From that moment on, I don’t remember a time that I didn’t want to be a doctor,” she said. “I had these really formative experiences with doctors who were so lovely, and I thought, ‘I want to do that.’ ”
Though she considered other specialties in medical school at the University of Toronto, Dr. Diorio kept feeling drawn back to pediatric oncology and hematology.
“I have always loved the commitment that parents have to their kids and the team approach that exists,” she said. “Hematology/oncology allowed me to take care of really sick kids but also have this long-term relationship with them and their parents, which I really value and love.”
Dr. Diorio even completed her residency at McMaster alongside one of the same physicians who had cared for her as a child, Ronald Duncan Barr, MD. “It sort of all came full circle,” she said.
But she takes that even further by researching new therapies for patients who have run out of options, particularly those with T-cell acute lymphoblastic leukemia (T-ALL).
For B-cell ALL and several other blood cancers, an effective option is CAR T-cell therapy, in which physicians collect T-cells from the patient, re-engineer the T cells in the lab so they recognize the proteins expressed on the surface of cancerous cells – called blasts – and then introduce the modified T-cells back into the patient. Once infused, the re-engineered T-cells attack the blasts with the tell-tale proteins.
But with T-ALL, T-cells themselves are infected with cancer, so autologous CAR T-cell therapy is not currently an option, and no allogeneic CAR T-cell therapies have been approved. Dr. Diorio is part of a cutting-edge research team led by David T. Teachey, MD, striving for breakthroughs. “She’s a brilliant clinician, extremely smart and hard-working, exceptional work ethic, great interaction with patients and families with a great bedside manner,” Dr. Teachey said of Dr. Diorio. “She’s just a superstar all around.”
Dr. Teachey first piqued Dr. Diorio’s interest in researching innovative T-ALL therapies when she arrived at CHOP as a hematology/oncology fellow in 2018 and pursued a master of science degree in translational research under his tutelage at the University of Pennsylvania. Then, for a time, the COVID-19 pandemic shut down most research.
“Caroline pivoted and was at the front line, collecting samples and helping with research on SARS-CoV-2 very early in the pandemic,” Dr. Teachey said. “She was able to then pivot back, taking the skills she learned from that work in the pandemic and applying it to what she was doing in the CAR T-cell space and T-ALL.”
Extraordinary gains in pediatric cancer over the past several decades mean that more than 80% of children diagnosed with cancer today will become long-term survivors. “The 20% of the time that we don’t get the result we want is obviously devastating,” Dr. Diorio said. “However, that’s incredibly motivating to try to make better treatments.”
Her current focus is finding a way to use CAR T-cell therapy in children with T-ALL. About 85% of children with T-ALL do well with standard first-line treatments of chemotherapy, but the 15% who relapse or have chemo-refractory disease have a far lower survival rate – less than 30%, Dr. Diorio said.
The problem with autologous CAR T-cell therapy in T-ALL is twofold: It’s difficult to sort out healthy T cells from the cancerous T cells, and the target current re-engineered T-cells go after is on healthy cells, too.
“What happens is a problem called fratricide – basically the CAR T-cells are killing their brothers,” she said. So Dr. Diorio and her colleagues are trying to modify CAR T-cell strategies to target different markers. One target they’re investigating is CD7, but using CRISPR to gene-edit out CD7 from healthy cells requires making two cuts in the DNA.
“Any time you break DNA, you have to repair it, and any time you repair it, there’s a chance of making a mistake,” Dr. Diorio said. So she used a different technique, cytosine-based editing, which requires only one cut. “You put in what you want, and it’s much more precise and less error-prone.” Cytosine-based editing also preserves T cells’ vitality; too many cuts impair T-cell growth, but that doesn’t happen with cytosine-based editing. In August of 2022, Dr. Diorio published a study demonstrating this technique while the team has continued looking for other targets that show up on cancer cells but not on healthy T-cells.
“I’m not invested in one particular strategy,” Dr. Diorio said. “I’m invested in finding a strategy that works for the maximum number of patients.”
That pragmatic approach may be why Dr. Teachey describes her as an out-of-the-box thinker.
“She brings novel ideas to the table, and not everybody who’s a physician-scientist has that ability to really think about taking things in the bench to the bedside and then back again,” Dr. Teachey said. “It’s knowing what questions are important to ask for our patients and how to study those and the research base, so that you can improve treatments for kids with leukemia.”
Their research looks promising so far. Clinical trials are in development for the CD7-targeted CAR T, and they’re collaborating with others on clinical trials for CAR-T targeting another protein, CD38. In the midst of it all, Dr. Diorio remains focused on her patients.
“It’s really a privilege to see the incredible grace people have in these very difficult circumstances,” Dr. Diorio said. “I find it really motivating to try to make things easier for people, and I try to spend every day looking for better treatments so people don’t have to go through that.”
Dr. Diorio has no disclosures. Dr. Teachey has served on the advisory boards of BEAM, Jazz, Janssen, and Sobi and has received research funding from BEAM, Jazz, Servier, and Neoimmune Tech. He has multiple patents pending on CAR-T therapy.