New Therapies May Reactivate Immune System in Resistant Melanoma
Researchers identify potential new strategies to overcome immunotherapy resistance in advanced melanoma, offering hope for improved patient outcomes.
Executive Brief
- The News: 14 CPMC patients' tumors analyzed after PD-1-based immunotherapy failure
- Clinical Win: Cobi+Reg combination restores antigen presentation and increases CD8+ T cells
- Target Specialty: Oncologists treating melanoma patients with BRAF-, NRAS- and NF1-mutant tumors
Key Data at a Glance
Study Design: Transcriptomic profiling and high-throughput drug screening
Sample Size: 14 CPMC patients with progressed melanoma and 15 treatment-naïve patients
Key Combination: Cobimetinib + regorafenib (Cobi+Reg)
Targeted Pathways: MAPK signaling, angiogenesis, and apoptosis
Key Result: Synergistic anti-tumor activity across multiple melanoma subtypes
Immune System Effect: Reactivation and increased infiltration of activated CD8+ T cells
New Therapies May Reactivate Immune System in Resistant Melanoma
Researchers at Sutter's California Pacific Medical Center (CPMC) in San Francisco, Calif. have identified potential new therapeutic strategies for patients with advanced melanoma who no longer respond to immunotherapy—an aim representing one of the most pressing clinical challenges in cancer care today.
The study, led by Mohammed Kashani-Sabet, M.D., medical director of CPMC's Cancer Center and an investigator at the CPMC Research Institute, builds on years of foundational work by the Cancer Avatar Program team at CPMC to better understand the biological basis of resistance to immune checkpoint blockade (ICB) therapies.
The findings appear in the Journal of Clinical Investigation and form the basis of a forthcoming investigator-initiated clinical trial at Sutter Health.
"Immunotherapy has transformed how we treat melanoma, but when it fails, our treatment options are extremely limited," says Dr. Kashani-Sabet. "We often need to resort to ineffective therapies developed decades ago. This study offers a new path forward."
Using transcriptomic profiling and high-throughput drug screening made possible by the Cancer Avatar Program, Dr. Kashani and team analyzed tumors from 14 CPMC patients whose melanoma had progressed after PD-1-based immunotherapy compared with tumors from 15 treatment-naïve patients. They identified several druggable genes and pathways, including those involved in mitogen activated protein kinase (MAPK) signaling, angiogenesis and apoptosis, and tested combinations of U.S. FDA-approved drugs targeting these pathways in patient-derived xenograft (PDX) models.
One combination, cobimetinib + regorafenib (Cobi+Reg), showed synergistic anti-tumor activity across multiple melanoma subtypes, including BRAF-, NRAS- and NF1-mutant tumors. The regimen also reversed key resistance mechanisms, including restoring antigen presentation and increasing infiltration of activated CD8+ T cells.
"Cobi+Reg not only shrank tumors in preclinical models—it reactivated the immune system," says Dr. Kashani-Sabet. "This opens the door to combining targeted therapy with immunotherapy for even greater benefit."
The study was conducted as part of the CPMC Cancer Avatar Program, a precision oncology initiative that uses living tumor models to guide treatment decisions. The project has already led to multiple clinical trials.
A CPMC-led clinical trial testing the promising combinations identified in patients with immunotherapy-resistant melanoma is now in development and is anticipated to begin enrolling patients by late 2025.
"This is a prime example of how precision oncology at Sutter is helping transform care for patients who need new options beyond standard of care," says Amanda Wheeler, M.D., chair of Sutter's cancer service line.
Clinical Perspective — Dr. Meera Pillai, Oncology
Workflow: As I manage patients with advanced melanoma, I'm now considering transcriptomic profiling to better understand resistance to immune checkpoint blockade therapies, as seen in the study of 14 CPMC patients. This approach may help identify druggable genes and pathways, such as MAPK signaling, to inform treatment decisions. With the Cancer Avatar Program, I'd have a new tool to guide personalized therapy.
Economics: The article doesn't address cost directly, but the potential to repurpose U.S. FDA-approved drugs like cobimetinib and regorafenib could impact treatment expenses. By combining targeted therapy with immunotherapy, we may be able to reduce costs associated with ineffective therapies developed decades ago. However, the economic implications of this approach require further study.
Patient Outcomes: The combination of cobimetinib and regorafenib (Cobi+Reg) showed promising results, with synergistic anti-tumor activity across multiple melanoma subtypes, including BRAF-, NRAS- and NF1-mutant tumors. This regimen also restored antigen presentation and increased infiltration of activated CD8+ T cells, which could lead to improved patient outcomes and increased survival rates in patients with immunotherapy-resistant melanoma.
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