Abemaciclib Demonstrates Significant Efficacy in Phase 3 Trial for Rare Dedifferentiated Liposarcoma
Key Insights
Abemaciclib significantly delayed cancer progression in patients with dedifferentiated liposarcoma (search), achieving a median progression-free survival of 9.7 months compared to 1.5 months with placebo in the SARC041 phase 3 trial.
The multicenter study enrolled 108 patients across nine centers and represents the first randomized controlled trial of abemaciclib for this rare and aggressive soft tissue sarcoma (search) subtype.
Results showed tumor shrinkage in some patients receiving abemaciclib while no responses were observed in the placebo group, with an encouraging trend toward improved overall survival.
Memorial Sloan Kettering Cancer Center physician-scientists have reported breakthrough results from the SARC041 phase 3 clinical trial, demonstrating that abemaciclib significantly delays disease progression in patients with dedifferentiated liposarcoma (search) (DDLPS (search)), a rare and aggressive soft tissue sarcoma (search). The findings were presented at the American Society of Clinical Oncology (ASCO (search)) annual meeting and featured in the meeting's plenary program.
Trial Results Show Dramatic Improvement
The randomized, placebo-controlled, double-blinded trial enrolled 108 patients across nine centers, with 54 patients receiving abemaciclib and 54 receiving placebo. Patients receiving abemaciclib achieved a median progression-free survival of 9.7 months compared to just 1.5 months in the placebo group - representing a six-fold improvement in disease control.
"These findings are especially encouraging because they show a targeted therapy can meaningfully delay disease progression in a cancer that has long been challenging to treat," said Mark A. Dickson, MD, an MSK (search) sarcoma medical oncologist and trial investigator who presented the results.
The study demonstrated several key efficacy outcomes:
- Tumors shrank in some patients receiving abemaciclib, while no responses were seen in the placebo group
- An encouraging trend toward improved overall survival was observed
- Approximately one-third of patients responded for significantly longer than average
- No new safety concerns were identified
Targeting CDK4/6 Pathway in DDLPS
Abemaciclib is a kinase inhibitor currently approved for certain breast cancers that works by blocking CDK4 (search) and CDK6 (search) proteins, which cancer cells require to grow and divide. The clinical trial was built upon earlier research suggesting DDLPS (search) may be especially vulnerable to CDK4 inhibition because the CDK4 gene is amplified in most DDLPS tumors.
"This trial is especially important because it shows that the benefits we've seen for MSK (search) patients can be shared with patients treated at other hospitals," Dr. Dickson noted. The research team, led by Dr. Dickson and William Tap, MD, Chief of MSK's Sarcoma Medical Oncology Service, has been treating sarcoma patients with CDK4 (search)/6 inhibitors for nearly 20 years in smaller, single-institution trials.
Addressing Critical Unmet Need
DDLPS (search) represents a particularly challenging cancer subtype, most often diagnosed in the abdomen or retroperitoneum and presenting significant treatment obstacles once it recurs or spreads. Current treatments have provided only modest benefit, with no FDA-approved therapies available for patients with metastatic disease.
Soft tissue sarcomas are rare cancers representing less than 1% of all adult cancers, with DDLPS (search) being a rare and aggressive subtype affecting adults typically between ages 50 and 75. The cancer often recurs following surgery and can metastasize, making long-term disease control difficult.
Patient Impact and Quality of Life
The clinical significance of these results is exemplified by patient Andi Straus, who enrolled in the trial in 2022 after facing multiple recurrences and an increasingly difficult prognosis. Despite being told she had a 50-50 chance of surviving five years when first diagnosed at age 70, she recently celebrated her 75th birthday.
"When I was first diagnosed, my surgeon told me I had a 50–50 chance of being alive in five years," Straus shared. "Every day since has felt like an indescribable miracle—one I'm profoundly grateful for." After initial side effects that required dose adjustment, Straus experienced tumor shrinkage and now maintains a high quality of life with minimal side effects.
Scientific Foundation and Future Implications
The trial's success builds on decades of laboratory and clinical research, including comprehensive genomic analysis initiated in 2009 as a collaboration between MSK (search) scientists and the Broad Institute. Research in the laboratories of Samuel Singer, MD, and Cristina Antonescu, MD, revealed that CDK4 (search)/6 frequently drives DDLPS (search) growth, providing the scientific rationale for testing abemaciclib in this cancer.
"These findings should shape how patients with this disease are treated going forward," said Dr. Tap. "Patients with DDLS currently have no good treatments after their cancer spreads, and this drug could really make a difference for many of them."
The research team hopes these results will lead to wider availability of the treatment and believes that administering abemaciclib earlier in the treatment course could benefit even more patients. The study was supported by Eli Lilly and Company, Cycle for Survival (search), the Mitchell Goodman Fund for Sarcoma Research, and the National Cancer Institute.