The discovery of immune checkpoint blockade as a therapeutic strategy to induce immunogenic cancer cell elimination has shown great success in the treatment of various cancers. However, limited response rates highlight the need for further development in this field. Promising new preclinical developments include the discoveries of proteolysis-targeting chimeras (PROTACs) to interfere with tumor immune escape signaling. Pharmacological induction of targeted protein degradation by these chimeras has shown advantages in inhibiting non-enzymatic protein functions and difficult to target protein–protein interactions. Furthermore, the induced degradation was shown to promote changes in the major histocompatibility complex I ligandome, which can be leveraged for an immune stimulus, increasing the cancer immune response. In this minireview, we highlight the research efforts ongoing towards employing PROTACs in immunotherapy for cancer treatment. Specifically, we outline how the unique mechanism of action can be leveraged to enhance the immune response or inhibit immune suppression.

Background/Objectives: Uveal melanoma (UVM), the leading primary intraocular cancer in adults, is driven by GNAQ/GNA11 mutations, encoding the active forms of Gαq proteins. While local treatments like surgery or radiation can control primary tumors, nearly half of patients die from metastasis. Our aim was identifying potential pathways involved in resistance to targeted therapy in UVM. Methods: Here, we screened 100 pathway-activating mutant complementary DNAs by lentiviral overexpression to identify those that enhance the survival of cancer cells in the presence of clinically relevant targeted therapies, using BAP1 wild-type UVM cells and validated the most significant results in BAP1-mutant cells. Results: This revealed JAK/STAT activation, overexpression of anti-apoptotic BCL2/BCL-XL, and dysregulated PI3K/mTOR or Hippo pathways as escape routes under MEK-ERK or FAK inhibition. Bioinformatic analysis of UVM transcriptome in TCGA further showed that high expression of the hallmark PI3K/AKT/mTOR pathway and IL6/JAK/STAT signaling correlates with poor prognosis. A similar correlation was shown by YAP and anti-apoptotic signatures. The analysis of individual representative genes from these signatures revealed that MTOR, BCL2L1 (BCL-XL), and TEAD4 gene expression are linked to poorer survival, underscoring the potential clinical impact of these adaptive pathways. Proliferation and apoptosis assay demonstrated that aberrant activation of AKT and YAP promotes resistance to FAK and MEK inhibitors. Conclusions: These findings support the adaptability of UVM lesions and suggest rational combination therapies targeting both primary GNAQ/GNA11-driven oncogenic signals and their compensatory networks as a more effective, personalized treatment approach for advanced UVM.

Fibrous dysplasia (FD) arises from activating GNAS mutations that increase cAMP signaling in skeletal stem/progenitor cells (SSPCs), but the underlying mechanisms and whether the resulting fate imbalance can be reversed remain unclear. Using controlled GNAS induction with transcriptomic, pharmacologic, and cell-fate analyses, we identify a PKA-dependent checkpoint governing SSPC lineage commitment. GNAS ^R201C redirects SSPCs toward osteoclastogenesis while suppressing osteoblast maturation; genetic or pharmacologic PKA inhibition reverses both effects, revealing this fate decision is dynamically reversible. Mechanistically, PKA phosphorylates RUNX2, the master regulator of osteogenesis, enforcing its cytoplasmic retention and blocking osteogenic transcription; a non-phosphorylatable RUNX2 mutant restores nuclear localization and osteoblast differentiation, defining RUNX2 phosphorylation as a disease-initiating molecular switch. Critically, PKA inhibition in vivo reduces fibrosis and osteoclast burden in established bone lesions, demonstrating reversibility even in advanced FD. These findings define a druggable GNAS-PKA-RUNX2 checkpoint and identify PKA inhibition as a strategy to reverse existing disease in FD. Graphical