Modern Therapies Expand Options for Soft-Tissue Sarcomas

Christina T. Loguidice
Published: Thursday, Nov 08, 2018
William D. Tap, MD from Memorial Sloan Kettering Cancer Center

William D. Tap, MD

Although soft-tissue sarcoma (STS) is seldom diagnosed in adults, the development of several new therapies in recent years for patients with rare subtypes is energizing leaders in the field and underscoring the need for a multidisciplinary approach to care.

Those were among the sentiments that a panel of experts expressed during a recent OncLive Peer Exchange®. “The idea that there is no effective treatment for sarcoma, or the idea of therapeutic nihilism, really needs to go away, because we are clearly making advances for our patients,” Richard F. Riedel, MD, said.

During the past 6 years, the FDA has approved 4 novel therapies for patients with STS subtypes, such as leiomyosarcoma and synovial sarcoma, who previously had limited therapeutic options (Table). Prior to those approvals, the drug approval activity in STS involved therapies for malignancies classified as gastrointestinal stromal tumors: imatinib (Gleevec) in 2002, sunitinib malate (Sutent) in 2006, and regorafenib (Stivarga) in 2013.1-3

Many of the new therapies are designed to benefit specific histologies, making treatment selection more complex, Jonathan C. Trent, MD, PhD, noted. “We have to work closely with our pathologists, and we have to use their expertise so that we can leverage all of these exciting new therapies for our patients and look forward to, potentially, some exciting combinations in the future,” he said.

The OncLive Peer Exchange® panelists provided their insights on establishing an accurate diagnosis of STS and discussed the most recent information surrounding treatment of these tumors and the use of modern therapies for advanced disease. They also provided their perspectives on how to apply the latest data to clinical care.

Diagnostic Challenges

Accurate diagnosis of STS poses a significant challenge. Collectively, these tumors constitute approximately 1% of all adult cancers yet are divided into more than 50 subtypes.4 “If one were to look in the pathology textbooks, there are over 200 types of soft-tissue sarcomas,” Trent said. They represent different kinds of cancer, he said, with fundamental differences in how they present, their biology and metastatic pattern, and how they are treated.

These tumors are also rare. “Benign tumors are 100-fold more common than malignant ones,” Victor Villalobos, MD, PhD, said. This sometimes leads to a false sense of security and, subsequently, an incorrect and potentially harmful treatment approach.

Table. Recent FDA Drug Approvals for STS Subtypes1-3

Table. Recent FDA Drug Approvals for STS Subtypes1-3 To ensure proper treatment, it is essential to accurately determine which sarcoma subtype a patient has. “We need to have an expert pathologist subtype the sarcoma,” Kristen N. Ganjoo, MD, said. “If you don’t have an expert pathologist, the diagnosis is sometimes different than what we actually have.”

The panelists thought that next-generation sequencing could be a helpful diagnostic tool for some patients with sarcomas. “I’ve actually been using next-generation sequencing for about 80% of my high-grade sarcomas—not the low grades—and I have been successful in certain cases to actually change the diagnosis,” Ganjoo said.

In this setting, a change in diagnosis has meaning because there could be very specific treatments for certain subtypes, moderator William D. Tap, MD, explained, noting that a change in diagnosis occurs approximately 15% of the time for patients coming from outside of tertiary care centers.

The panel emphasized the importance of taking a multidisciplinary approach to care and discussing sarcoma cases with colleagues, particularly those experienced with sarcomas. “[Despite being at a sarcoma center], there are a few cases a year of something I’ve still never seen,” Riedel said. Like others on the panel, his institution has a multidisciplinary tumor board to facilitate such discussions. 

“With more people in the room, you have hundreds of years of experience between people who have seen these tumors. It really makes care optimal to these patients,” Villalobos added.

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