Robert Preece

Fueling a Long-Awaited Breakthrough for Sarcoma Patients

In 2023, Australian marathon runner Robert Preece felt like he was at the top of his game. When he wasn’t competing in marathons, cycling, or bushwalking, he was chasing his granddaughter around the park. Life felt full.

Then, after one run, he noticed an unusual soreness in his right thigh. He assumed he had pulled a muscle, but the pain wouldn’t go away. Soon, a lump appeared on his thigh and began growing rapidly.

“My general practitioner, who was very cancer-aware, said straight away, ‘I don’t like the look of this,’” Preece recalled. “He sent me off for imaging immediately.”

A biopsy soon revealed a devastating diagnosis: stage 3 undifferentiated pleomorphic sarcoma (UPS), a rare and aggressive soft-tissue cancer.

For patients with this stage and type of sarcoma, the prognosis has long been a coin toss. Even after radiation and surgery, the cancer returns in roughly half of patients, often having spread, or metastasized, to other parts of the body. But Preece’s diagnosis came at an opportune moment.

His doctor told him about an international clinical trial funded by Stand Up To Cancer (SU2C). At the time, the standard treatment for stage 3 UPS was radiation followed by surgery (in stage 3 UPS, there is a single large tumor but the cancer hasn’t spread). The trial, called SU2C-SARC032, was testing whether adding the immunotherapy drug pembrolizumab (Ketyruda) to radiation and surgery would be more effective than the combination alone. Hoping to improve his odds of avoiding a recurrence, Preece enrolled in the study. As it turned out, he was randomly assigned to the group in the trial that would receive pembrolizumab.

In 2024, the results showed precisely what the trial’s investigators had hoped they would: patients who received pembrolizumab were far more likely to remain cancer-free than those who received standard treatment alone. More than two and a half years after his diagnosis, Preece remains free of sarcoma.

“I feel incredibly lucky,” he said. “This trial was life saving for me.”

The trial results have already changed clinical practice in the United States, where using pembrolizumab along with radiation and surgery is now recommended as a standard of care for patients with UPS and another rare sarcoma subtype, pleomorphic/dedifferentiated liposarcoma (LPS).

Rob Preece enjoying ice cream with his granddaughter, Maya.

For a disease that had seen little progress in nearly 30 years, the trial marked a long-awaited breakthrough and offered new hope to patients around the world, explained the trial’s lead researcher, David Kirsch, MD, PhD, of the Princess Margaret Cancer Centre in Toronto.

“This is a major step forward for our patients,” Dr. Kirsch said. “We’ve been watching other more common cancers gain many new treatment options, and sarcoma has been stuck without any advances for decades. Now, there’s a path forward to help patients have better outcomes.”

Dr. David Kirsch presents findings from genomic studies of participants in the SU2C-SARC032 trial at the SU2C Scientific Summit 2026.

A clinical trial for an extremely rare cancer

Developing new treatments for soft-tissue sarcomas, of which there are more than 50 subtypes, has long been a challenge. These cancers account for just 1% of adult cancer diagnoses, making it difficult to enroll patients in clinical trials and conduct the types of rigorous studies that can provide meaningful results. Funding for research on rare cancers is also often limited.

“As a result, the standard of care for patients with sarcomas had been unchanged for a couple of decades, with radiation and surgery being the main ways we would treat them,” said trial investigator Everett Moding, MD, PhD, who specializes in treating sarcomas at Stanford University.

Sarcoma researchers began to see a potential path to progress in 2017 with the results of a clinical trial called SARC028. The trial tested pembrolizumab in patients with advanced soft-tissue sarcomas, showing encouraging activity against several subtypes, including UPS and LPS.

“We knew that those two types of sarcoma could respond to pembrolizumab on its own,” Dr. Kirsch said. “We wanted to test what happens if we added it to radiation therapy and then gave it again after surgery.”

The rationale for this pre- and post-surgery immunotherapy approach was to provide the immune system with as much assistance as possible. A type of drug known as an immune checkpoint inhibitor, pembrolizumab works by helping immune cells “see” cancer cells. Drs. Kirsch and Moding suspected that initially giving the drug for a short time before surgery, with the tumor fully intact, would be like giving the immune system a crash course on its ultimate objective: Attack anything that resembles this. So, even after the tumor’s been removed, the immune system would be revved up and ready to eradicate any cancer cells remaining in the body.

SU2C-SARC032 was launched to test this idea.

The results marked the first major advance in treatment for these sarcoma subtypes in a generation, Dr. Kirsch said. At two years after completing the treatment, 67% of patients who received pembrolizumab had not had a recurrence, compared with 52% of patients who received standard therapy alone.

“For a long time, we treated patients knowing that about half of them would develop metastatic disease, and we would have nothing to do for them,” Dr. Moding said. “Having something to actually do to prevent that from happening is really gratifying.”

The power of international collaboration

Completing this trial required an extraordinary level of coordination. To enroll 143 patients to the trial, the researchers had to build an international network spanning 20 hospitals across the United States, Canada, Italy, and Australia.

“That is a big number for a sarcoma trial,” said Angela Hong, MD, PhD, of the University of Sydney, the lead investigator for the trial in Australia. “If you look at a breast cancer trial, or a prostate cancer trial, they usually accrue thousands of patients.” With a rare cancer like sarcoma, she continued, it would take many years to enroll that many patients in a trial, and even longer to complete it.  Researchers studying sarcoma “will have moved on by the time you finish recruiting.”

Even so, recruitment took six years, a reflection of both the rarity of the disease and the determination of the investigators involved. Australia alone contributed 45 patients, nearly one-third of the trial’s participants, including Robert Preece. “This kind of trial simply isn’t possible without international collaboration,” Dr. Hong noted.

The effort was made possible through an SU2C Catalyst grant supported by Merck and the Sarcoma Alliance for Research through Collaboration.

“They prioritized investing in a disease that’s rare but where there was the potential to have a massive impact,” Dr. Kirsch says. “Because of that investment, we have new treatment options now for these sarcoma patients that we didn’t in the past.”

Hoping to leave a legacy

The work is far from over. Through the Canadian Clinical Trials Group, a larger trial is being launched with the goal of helping doctors better understand how to best use immunotherapy and radiation therapy as a treatment for patients with high-risk sarcomas.

In addition, using resources like tumor and blood samples collected from participants in SU2C-SARC032, the trial research team has been conducting studies that may provide important details about why immunotherapy drugs like pembrolizumab works in some patients but not in others. Thus far, they’ve discovered some important clues.

“We have learned a lot about the biology of these tumors,” Dr. Moding said.

He’s hopeful that, eventually, their research will help oncologists tailor treatment to individual patients with sarcomas, including potentially using so-called liquid biopsies that can identify potential recurrences well before tumors appear.

For Dr. Moding, one of the most important legacies of having conducted this trial is the scientific foundation it created for future discoveries.

“This trial would not have been possible without Stand Up To Cancer support and recognizing the potential impact for patients with rare cancers where there hasn’t been a treatment advance in a long time,” he said. “This will help personalize treatment in the future and extend beyond the impact of just this one advance.”

A new lease on life

Robert Preece’s life looks very different today than it did before that afternoon run several years ago.

His original surgery completely removed the tumor in his leg, but the cancer left him with lasting physical challenges. He can no longer run marathons or chase his granddaughter through the park, and his loss of mobility ultimately forced him into early retirement.

As he explained, however, he chooses to focus not on what he has lost but on what he can do.

Today, he serves as a patient advocate, volunteering with sarcoma organizations and lobbying for government support to make immunotherapy more accessible and affordable for patients and families. Although there’s a chance the cancer could still return, the odds are now in his favor.

“You’d much rather face a one in three chance than one in two,” Preece said. “That is good for your mental health.”

Stand Up To Cancer raises awareness and funds research to detect and treat cancers with the aspiration to cure all patients. Find out how you can get involved.