MDM2 Inhibition Enhances Immune Checkpoint Inhibitor Efficacy by Increasing IL15 and MHC Class II Production

Targeting p53 for immune modulation: Exploring its functions in tumor immunity and inflammation

p53, often referred to as the "guardian of the genome," is a critical regulator of cellular responses to stress. p53 plays a dual role in tumor suppression and immune regulation. In addition to its well-known functions of maintaining genomic stability and inducing apoptosis, p53 orchestrates a complex interaction between innate and adaptive immune responses. This involvement contributes to pathogen clearance, immune surveillance, and immunogenic cell death (ICD). This review explores the influence of p53 on immune dynamics, detailing its effects on macrophages, dendritic cells, natural killer cells (NK), T cells, and B cells. This review explains how mutations in p53 disrupt immune responses, promoting tumor immune evasion, and highlights its regulation of inflammatory cytokines and pattern recognition receptors. Furthermore, p53's role in ICD marks it as a key player in antitumor immunity, which has significant implications for cancer immunotherapy. The review also discusses the role of p53 in inflammation, autoimmune diseases, and chronic infections, revealing its dual function in promoting and suppressing inflammation through interactions with NF-κB signaling. Therapeutically, approaches that target p53, including wild-type p53 reactivation and combination therapies with immune checkpoint inhibitors, show considerable promise. Advances in high-throughput technologies, such as single-cell RNA sequencing and CRISPR screens, provide new insights into the immunological functions of p53, including its role in microbiome-immune interactions and immune senescence. This comprehensive review highlights the importance of incorporating immunological insights from p53 into innovative therapeutic strategies, addressing existing knowledge gaps, and paving the way for personalized medicine.

Dual role of interferon-gamma in the response of melanoma patients to immunotherapy with immune checkpoint inhibitors

Interferon-gamma (IFN-γ) is a cytokine produced mainly by immune cells and can affect cancer cells by modulating the activity of multiple signaling pathways, including the canonical Janus-activated kinase/signal transducer and activator of transcription (JAK/STAT) cascade. In melanoma, IFN-γ can exert both anticancer effects associated with cell-cycle arrest and cell death induction and protumorigenic activity related to immune evasion leading to melanoma progression. Notably, IFN-γ plays a crucial role in the response of melanoma patients to immunotherapy with immune checkpoint inhibitors (ICIs), which are currently used in the clinic. As these agents target programmed death-1 (PD-1) and its ligand (PD-L1), cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) and lymphocyte-activation gene 3 (LAG-3), they are designed to restore the antimelanoma immune response. In this respect, IFN-γ produced by cells in the tumor microenvironment in response to ICIs has a beneficial influence on both immune and melanoma cells by increasing antigen presentation, recruiting additional T-cells to the tumor site, and inducing direct antiproliferative effects and apoptosis in melanoma cells. Therefore, IFN-γ itself and IFN-γ-related gene signatures during the response to ICIs can constitute biomarkers or predictors of the clinical outcome of melanoma patients treated with ICIs. However, owing to its multifaceted roles, IFN-γ can also contribute to developing mechanisms associated with the acquisition of resistance to ICIs. These mechanisms can be associated with either decreased IFN-γ levels in the tumor microenvironment or diminished responsiveness to IFN-γ due to changes in the melanoma phenotypes associated with affected activity of other signaling pathways or genetic alterations e.g., in JAK, which restricts the ability of melanoma cells to respond to IFN-γ. In this respect, the influence of IFN-γ on melanoma-specific regulators of the dynamic plasticity of the cell phenotype, including microphthalmia-associated transcription factor (MITF) and nerve growth factor receptor (NGFR)/CD271 can affect the clinical efficacy of ICIs. This review comprehensively discusses the role of IFN-γ in the response of melanoma patients to ICIs with respect to its positive influence and role in IFN-γ-related mechanisms of resistance to ICIs as well as the potential use of predictive markers on the basis of IFN-γ levels and signatures of IFN-γ-dependent genes.

TP53 Deficiency in the Natural History of Prostate Cancer

Prostate cancer remains a leading cause of cancer-related mortality in men, with advanced stages posing significant treatment challenges due to high morbidity and mortality. Among genetic alterations, TP53 mutations are among the most prevalent in cancers and are strongly associated with poor clinical outcomes and therapeutic resistance. This review investigates the role of TP53 mutations in prostate cancer progression, prognosis, and therapeutic development. A comprehensive analysis of preclinical and clinical studies was conducted to elucidate the molecular mechanisms, clinical implications, and potential therapeutic approaches associated with TP53 alterations in prostate cancer. TP53 mutations are highly prevalent in advanced stages, contributing to genomic instability, aggressive tumor phenotypes, and resistance to standard treatments. Emerging evidence supports the utility of liquid biopsy techniques, such as circulating tumor DNA analysis, for detecting TP53 mutations, providing prognostic value and facilitating early intervention strategies. Novel therapeutic approaches targeting TP53 have shown promise in preclinical settings, but their clinical efficacy requires further validation. Overall, TP53 mutations represent a critical biomarker for disease progression and therapeutic response in prostate cancer. Advances in detection methods and targeted therapies hold significant potential to improve outcomes for patients with TP53-mutated prostate cancer. Further research is essential to integrate TP53-based strategies into routine clinical practice.

A Perspective on Therapeutic Targeting Against Ubiquitin Ligases to Stabilize Tumor Suppressor Proteins

The loss of functions of tumor suppressor (TS) genes plays a key role in not only tumor initiation but also tumor progression leading to poor prognosis. While therapeutic inhibition of oncogene-encoded kinases has shown clinical success, restoring TS functions remains challenging due to conceptual and technical limitations. E3 ubiquitin ligases that ubiquitinate TS proteins for accelerated degradation in cancers emerge as promising therapeutic targets. Unlike proteasomal inhibitors with a broad spectrum, inhibitors of an E3 ligase would offer superior selectivity and efficacy in enhancing expression of its substrate TS proteins as far as the TS proteins retain wild-type structures. Recent advances in developing E3 inhibitors, including MDM2 inhibitors, highlight their potential and ultimately guide the framework to establish E3 inhibition as effective strategies to treat specific types of cancers. This review explores E3 ligases that negatively regulate bona fide TS proteins, the developmental status of E3 inhibitors, and their promise and pitfalls as therapeutic agents for anti-cancer precision medicine.

Advances in cell therapy: progress and challenges in hematological and solid tumors

Cell-based therapies harness the endogenous ability of the immune system to fight cancer and have shown promising results in the treatment of hematological malignancies. However, their clinical application beyond B cell malignancies is hampered by numerous hurdles, ranging from relapsed disease to a hostile tumor microenvironment (TME). Recent advances in cell engineering and TME modulation may expand the applicability of these therapies to a wider range of cancers, creating new treatment possibilities. Breakthroughs in advanced gene editing and sophisticated cell engineering, have also provided promising solutions to longstanding challenges. In this review, we examine the challenges and future directions of the most prominent cell-based therapies, including chimeric antigen receptor (CAR)-T cells, tumor-infiltrating lymphocytes (TILs), and natural killer (NK) cells, and emerging modalities. We provide a comprehensive analysis of emerging cell types and combination strategies translated into clinical trials, offering insights into the next generation of cell-based cancer treatments.

Comprehensive Analysis of the SUMO-related Signature: Implication for Diagnosis, Prognosis, and Immune Therapeutic Approaches in Cervical Cancer

SUMOylation, an important post-translational protein modification, plays a critical role in cancer development and immune processes. This study aimed to construct diagnostic and prognostic models for cervical cancer (CC) using SUMOylation-related genes (SRGs) and explore their implications for novel clinical therapies. We analyzed the expression profiles of SRGs in CC patients and identified 15 SRGs associated with CC occurrence. After the subsequent qPCR verification of 20 cases of cancer and adjacent tissues, 13 of the 15 SRGs were differentially expressed in cancer tissues. Additionally, we identified molecular markers associated with the prognosis and recurrence of CC patients, based on SRGs. Next, a SUMOScore, based on SRG expression patterns, was generated to stratify patients into different subgroups. The SUMOScore showed significant associations with the tumor microenvironment, immune function features, immune checkpoint expression, and immune evasion score in CC patients, highlighting the strong connection between SUMOylation factors and immune processes. In terms of immune therapy, our analysis identified specific chemotherapy drugs with higher sensitivity in the subgroups characterized by high and low SUMOScore, indicating potential treatment options. Furthermore, we conducted drug sensitivity analysis to evaluate the response of different patient subgroups to conventional chemotherapy drugs. Our findings revealed enrichment of immune-related pathways in the low-risk subgroup identified by the prognostic model. In conclusion, this study presents diagnostic and prognostic models based on SRGs, accompanied by a comprehensive index derived from SRGs expression patterns. These findings offer valuable insights for CC diagnosis, prognosis, treatment, and immune-related analysis.

An update patent review of MDM2-p53 interaction inhibitors (2019-2023)

INTRODUCTION

The activity of the major tumor suppressor protein p53 is disrupted in nearly all human cancer types, either by mutations in TP53 gene or by overexpression of its negative regulator, Mouse Double Minute 2 (MDM2). The release of p53 from MDM2 and its homolog MDM4 with inhibitors based on different chemistries opened up a prospect for a broad, non-genotoxic anticancer therapy.

AREAS COVERED

This article reviews the patents and patent applications between years 2019 and 2023 in the field of MDM2-p53 interaction inhibitors. The newly reported molecules searched in Espacenet, Google Patents, and PubMed were grouped into five general categories: compounds having single-ring, multi-ring, or spiro-oxindole scaffolds, peptide derivatives, and proteolysis-targeting chimeras (PROTACs). The article also presents the progress of MDM2 antagonists of various structures in recruiting or completed cancer clinical trials.

EXPERT OPINION

Despite 20 years of intensive studies after the discovery of the first-in-class small-molecule inhibitor, Nutlin-3, no drugs targeting MDM2-p53 interaction have reached the market. Nevertheless, more than 10 compounds are still being evaluated in clinics, both as standalone drugs and in combinations with other targeted therapies or standard chemotherapy agents, including two inhibitors in phase 3 studies and two compounds granted orphan-drug/fast-track designation by the FDA.

MDM2 inhibitors in cancer immunotherapy: Current status and perspective

Murine double minute 2 (MDM2) plays an essential role in the cell cycle, apoptosis, DNA repair, and oncogene activation through p53-dependent and p53-independent signaling pathways. Several preclinical studies have shown that MDM2 is involved in tumor immune evasion. Therefore, MDM2-based regulation of tumor cell-intrinsic immunoregulation and the immune microenvironment has attracted increasing research attention. In recent years, immune checkpoint inhibitors targeting PD-1/PD-L1 have been widely used in the clinic. However, the effectiveness of a single agent is only approximately 20%-40%, which may be related to primary and secondary drug resistance caused by the dysregulation of oncoproteins. Here, we reviewed the role of MDM2 in regulating the immune microenvironment, tumor immune evasion, and hyperprogression during immunotherapy. In addition, we summarized preclinical and clinical findings on the use of MDM2 inhibitors in combination with immunotherapy in tumors with MDM2 overexpression or amplification. The results reveal that the inhibition of MDM2 could be a promising strategy for enhancing immunotherapy.

Inverse correlation between TP53 gene status and PD-L1 protein levels in a melanoma cell model depends on an IRF1/SOX10 regulatory axis

BACKGROUND

PD-L1 expression on cancer cells is an important mechanism of tumor immune escape, and immunotherapy targeting the PD-L1/PD1 interaction is a common treatment option for patients with melanoma. However, many patients do not respond to treatment and novel predictors of response are emerging. One suggested modifier of PD-L1 is the p53 pathway, although the relationship of p53 pathway function and activation is poorly understood.

METHODS

The study was performed on human melanoma cell lines with various p53 status. We investigated PD-L1 and proteins involved in IFNγ signaling by immunoblotting and mRNA expression, as well as membrane expression of PD-L1 by flow cytometry. We evaluated differences in the ability of NK cells to recognize and kill target tumor cells on the basis of p53 status. We also investigated the influence of proteasomal degradation and protein half-life, IFNγ signaling and p53 activation on biological outcomes, and performed bioinformatic analysis using available data for melanoma cell lines and melanoma patients.

RESULTS

We demonstrate that p53 status changes the level of membrane and total PD-L1 protein through IRF1 regulation and show that p53 loss influences the recently discovered SOX10/IRF1 regulatory axis. Bioinformatic analysis identified a dependency of SOX10 on p53 status in melanoma, and a co-regulation of immune signaling by both transcription factors. However, IRF1/PD-L1 regulation by p53 activation revealed complicated regulatory mechanisms that alter IRF1 mRNA but not protein levels. IFNγ activation revealed no dramatic differences based on TP53 status, although dual p53 activation and IFNγ treatment confirmed a complex regulatory loop between p53 and the IRF1/PD-L1 axis.

CONCLUSIONS

We show that p53 loss influences the level of PD-L1 through IRF1 and SOX10 in an isogenic melanoma cell model, and that p53 loss affects NK-cell cytotoxicity toward tumor cells. Moreover, activation of p53 by MDM2 inhibition has a complex effect on IRF1/PD-L1 activation. These findings indicate that evaluation of p53 status in patients with melanoma will be important for predicting the response to PD-L1 monotherapy and/or dual treatments where p53 pathways participate in the overall response.

TP53 Mutation-Mediated Immune Evasion in Cancer: Mechanisms and Therapeutic Implications

Mutation in p53 is the most frequent event in cancer development and a leading cause of cancer therapy resistance due to evasion of the apoptosis cascade. Beyond chemotherapies and radiation therapies, growing evidence indicates that p53-mutant tumors are resistant to a broad range of immune-based therapies, such as immune checkpoint inhibitors, chimeric antigen receptor (CAR) T, and hematopoietic stem cell transplantation (HSCT). This highlights the role of p53 mutations in driving immune evasion of tumor cells. In this review, we first summarize recent studies revealing mechanisms by which p53-mutant tumors evade immune surveillance from T cells, natural killer (NK) cells, and macrophages. We then review how these mutant tumor cells reshape the tumor microenvironment (TME), modulating bystander cells such as macrophages, neutrophils, and regulatory T (Treg) cells to foster immunosuppression. Additionally, we review clinical observations indicative of immune evasion associated with p53 loss or mutations. Finally, we discuss therapeutic strategies to enhance immune response in p53 wild-type (WT) or mutant tumors.

The role of the MDM2/p53 axis in antitumor immune responses

ABSTRACT

Mouse double minute 2 homolog (MDM2) is a negative regulator of the tumor suppressor p53 and is often highly expressed in acute myeloid leukemia (AML) and other solid tumors. Inactivating mutations in TP53, the gene encoding p53, confers an unfavorable prognosis in AML and increases the risk for relapse after allogeneic hematopoietic cell transplantation. We review the concept that manipulation of MDM2 and p53 could enhance immunogenicity of AML and solid tumor cells. Additionally, we discuss the mechanisms by which MDM2 and p53 regulate the expression of major histocompatibility complex class I and II, transcription of double stranded RNA of endogenous retroviruses, responses of interferons, production of interleukin-15, and expression of tumor necrosis factor-related apoptosis-inducing ligand receptor 1 and 2 on malignant cells. The direct effects of MDM2 inhibition or MDM2 deletion in effector T cells are discussed in the context of cancer immunotherapy. The preclinical findings are connected to clinical studies using MDM2 inhibition to enhance antitumor immunity in patients. This review summarizes current evidence supporting the use of MDM2 inhibition to restore p53 as well as the direct effects of MDM2 inhibition on T cells as an emerging concept for combined antitumor immunotherapy against hematological malignancies and beyond.

Tricking the trickster: precision medicine approaches to counteract leukemia immune escape after transplant

ABSTRACT

Over the last decades, significant improvements in reducing the toxicities of allogeneic hematopoietic cell transplantation (allo-HCT) have widened its use as consolidation or salvage therapy for high-risk hematological malignancies. Nevertheless, relapse of the original malignant disease remains an open issue with unsatisfactory salvage options and limited rationales to select among them. In the last years, several studies have highlighted that relapse is often associated with specific genomic and nongenomic mechanisms of immune escape. In this review we summarize the current knowledge about these modalities of immune evasion, focusing on the mechanisms that leverage antigen presentation and pathologic rewiring of the bone marrow microenvironment. We present examples of how this biologic information can be translated into specific approaches to treat relapse, discuss the status of the clinical trials for patients who relapsed after a transplant, and show how dissecting the complex immunobiology of allo-HCT represents a crucial step toward developing new personalized approaches to improve clinical outcomes.

MDM2 Inhibitors for Cancer Therapy: The Past, Present, and Future

Since its discovery over 35 years ago, MDM2 has emerged as an attractive target for the development of cancer therapy. MDM2's activities extend from carcinogenesis to immunity to the response to various cancer therapies. Since the report of the first MDM2 inhibitor more than 30 years ago, various approaches to inhibit MDM2 have been attempted, with hundreds of small-molecule inhibitors evaluated in preclinical studies and numerous molecules tested in clinical trials. Although many MDM2 inhibitors and degraders have been evaluated in clinical trials, there is currently no Food and Drug Administration (FDA)-approved MDM2 inhibitor on the market. Nevertheless, there are several current clinical trials of promising agents that may overcome the past failures, including agents granted FDA orphan drug or fast-track status. We herein summarize the research efforts to discover and develop MDM2 inhibitors, focusing on those that induce MDM2 degradation and exert anticancer activity, regardless of the p53 status of the cancer. We also describe how preclinical and clinical investigations have moved toward combining MDM2 inhibitors with other agents, including immune checkpoint inhibitors. Finally, we discuss the current challenges and future directions to accelerate the clinical application of MDM2 inhibitors. In conclusion, targeting MDM2 remains a promising treatment approach, and targeting MDM2 for protein degradation represents a novel strategy to downregulate MDM2 without the side effects of the existing agents blocking p53-MDM2 binding. Additional preclinical and clinical investigations are needed to finally realize the full potential of MDM2 inhibition in treating cancer and other chronic diseases where MDM2 has been implicated. SIGNIFICANCE STATEMENT: Overexpression/amplification of the MDM2 oncogene has been detected in various human cancers and is associated with disease progression, treatment resistance, and poor patient outcomes. This article reviews the previous, current, and emerging MDM2-targeted therapies and summarizes the preclinical and clinical studies combining MDM2 inhibitors with chemotherapy and immunotherapy regimens. The findings of these contemporary studies may lead to safer and more effective treatments for patients with cancers overexpressing MDM2.

Targeting MDM2 in malignancies is a promising strategy for overcoming resistance to anticancer immunotherapy

MDM2 has been established as a biomarker indicating poor prognosis for individuals undergoing immune checkpoint inhibitor (ICI) treatment for different malignancies by various pancancer studies. Specifically, patients who have MDM2 amplification are vulnerable to the development of hyperprogressive disease (HPD) following anticancer immunotherapy, resulting in marked deleterious effects on survival rates. The mechanism of MDM2 involves its role as an oncogene during the development of malignancy, and MDM2 can promote both metastasis and tumor cell proliferation, which indirectly leads to disease progression. Moreover, MDM2 is vitally involved in modifying the tumor immune microenvironment (TIME) as well as in influencing immune cells, eventually facilitating immune evasion and tolerance. Encouragingly, various MDM2 inhibitors have exhibited efficacy in relieving the TIME suppression caused by MDM2. These results demonstrate the prospects for breakthroughs in combination therapy using MDM2 inhibitors and anticancer immunotherapy.