Can Pembrolizumab Improve Outcomes in Soft-Tissue Sarcoma?

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The PD-1 inhibitor pembrolizumab may offer benefit in patients with soft-tissue sarcoma, according to recent findings presented by Mowery et al at the 2024 ASCO Annual Meeting (Abstract 11504).


Soft-tissue sarcoma is a rare type of cancer affecting muscles, fat, and other connective tissues. Because the disease is diagnosed in only about 15,000 U.S. patients per year, there are not always a sufficient number of eligible patients for clinical studies. As a result, there has been little advancement in the treatment of the disease over the past 30 years.

“Sarcoma doesn’t affect anywhere near the number of patients as breast, lung, prostate, or colorectal cancer, but [patients] impacted by sarcoma arguably need clinical trials even more,” suggested Steven Young, President and Chief Executive Officer of the Sarcoma Alliance for Research through Collaboration (SARC).

Standard therapy for nonmetastatic soft-tissue sarcoma typically consists of radiation therapy followed by surgery. However, approximately 50% of patients with high-risk sarcomas experience subsequent cancer recurrence or metastasis after treatment.

Previous studies have shown that patients with undifferentiated pleomorphic sarcoma and pleomorphic/dedifferentiated liposarcoma and established metastases may respond to pembrolizumab.

“Immunotherapies have transformed cancer care for many cancers, but in the 25 years I have been caring for [patients with] sarcoma, we haven’t seen any significant advances for [soft-tissue] sarcomas. This study will change that,” stressed senior study author David Kirsch, MD, PhD, Leader of the Stand Up To Cancer (SU2C) Catalyst Research Team and Head of the Radiation Medicine Program at the Princess Margaret Cancer Centre at the University Health Network in Toronto. “From my point of view, this is the most important study for patients with these sarcomas in 30 years because it’s addressing an important unmet need,” he added.

Study Methods and Results

In the SU2C-SARC032 trial, researchers enrolled 127 patients with sarcoma from 20 hospitals across the United States, Canada, Italy, and Australia over the course of 6 years. They then randomly assigned the patients to receive pembrolizumab before, during, and after radiation therapy and again after surgery or standard therapy.

The researchers found that the 2-year risk of relapse was reduced by 43% in the patients who received pembrolizumab compared with those who received standard therapy.


“It takes big ideas, unique collaborations, and in some cases, a global effort to help bring breakthroughs to patients impacted by rare cancers,” emphasized Julian Adams, PhD, President and Chief Executive Officer of SU2C. “We believed this could work with the SU2C Catalyst approach, support from our donor Merck, and input from the best minds in sarcoma research across the world,” he continued.

“SARC was delighted to have this research build on our prior trial to determine if we could achieve meaningful advances of novel treatment strategies that will profoundly impact the sarcoma community,” stated Mr. Young.

Disclosure: The research in this study was funded by SU2C as well as supported by Merck’s Investigator Studies Program and SARC. For full disclosures of the study authors, visit

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.