Host immunity contributes to the anti-melanoma activity of BRAF inhibitors

Repolarization of Immunosuppressive Macrophages by Targeting SLAMF7-Regulated CCL2 Signaling Sensitizes Hepatocellular Carcinoma to Immunotherapy

Immune checkpoint inhibitors have limited efficacy in hepatocellular carcinoma (HCC). Macrophages are the most abundant immune cells in HCC, suggesting that a better understanding of the intrinsic processes by which tumor cells regulate macrophages could help identify strategies to improve response to immunotherapy. As signaling lymphocytic activation molecule (SLAM) family members regulate various immune functions, we investigated the role of specific SLAM receptors in the immunobiology of HCC. Comparison of the transcriptomic landscapes of immunotherapy-responsive and nonresponsive patients with advanced HCC identified SLAMF7 upregulation in immunotherapy-responsive HCC, and patients with HCC who responded to immunotherapy also displayed higher serum levels of SLAMF7. Loss of Slamf7 in liver-specific knockout mice led to increased hepatocarcinogenesis and metastasis, elevated immunosuppressive macrophage infiltration, and upregulated PD-1 expression in CD8+ T cells. HCC cell-intrinsic SLAMF7 suppressed MAPK/ATF2-mediated CCL2 expression to regulate macrophage migration and polarization in vitro. Mechanistically, SLAMF7 associated with SH2 domain-containing adaptor protein B (SHB) through its cytoplasmic 304 tyrosine site to facilitate the recruitment of SHIP1 to SLAMF7 and inhibit the ubiquitination of TRAF6, thereby attenuating MAPK pathway activation and CCL2 transcription. Pharmacological antagonism of the CCL2/CCR2 axis potentiated the therapeutic effect of anti-PD-1 antibody in orthotopic HCC mouse models with low SLAMF7 expression. In conclusion, this study highlights SLAMF7 as a regulator of macrophage function and a potential predictive biomarker of immunotherapy response in HCC. Strategies targeting CCL2 signaling to induce macrophage repolarization in HCC with low SLAMF7 might enhance the efficacy of immunotherapy.

SIGNIFICANCE

CCL2 upregulation caused by SLAMF7 deficiency in hepatocellular carcinoma cells induces immunosuppressive macrophage polarization and confers resistance to immune checkpoint blockade, providing potential biomarkers and targets to improve immunotherapy response in patients.

Rapidly Evolving Pre- and Post-surgical Systemic Treatment of Melanoma

With the development of effective BRAF-targeted and immune-checkpoint immunotherapies for metastatic melanoma, clinical trials are moving these treatments into earlier adjuvant and perioperative settings. BRAF-targeted therapy is a standard of care in resected stage III-IV melanoma, while anti-programmed death-1 (PD1) immunotherapy is now a standard of care option in resected stage IIB through IV disease. With both modalities, recurrence-free survival and distant-metastasis-free survival are improved by a relative 35-50%, yet no improvement in overall survival has been demonstrated. Neoadjuvant anti-PD1 therapy improves event-free survival by approximately an absolute 23%, although improvements in overall survival have yet to be demonstrated. Understanding which patients are most likely to recur and which are most likely to benefit from treatment is now the highest priority question in the field. Biomarker analyses, such as gene expression profiling of the primary lesion and circulating DNA, are preliminarily exciting as potential biomarkers, though each has drawbacks. As in the setting of metastatic disease, markers that inform positive outcomes include interferon-γ gene expression, PD-L1, and high tumor mutational burden, while negative predictors of outcome include circulating factors such as lactate dehydrogenase, interleukin-8, and C-reactive protein. Integrating and validating these markers into clinically relevant models is thus a high priority. Melanoma therapeutics continues to advance with combination adjuvant approaches now investigating anti-PD1 with lymphocyte activation gene 3 (LAG3), T-cell immunoreceptor with Ig and ITIM domains (TIGIT), and individualized neoantigen therapies. How this progress will be integrated into the management of a unique patient to reduce recurrence, limit toxicity, and avoid over-treatment will dominate clinical research and patient care over the next decade.

Tumor-targeted therapy with BRAF-inhibitor recruits activated dendritic cells to promote tumor immunity in melanoma

BACKGROUND

Tumor-targeted therapy causes impressive tumor regression, but the emergence of resistance limits long-term survival benefits in patients. Little information is available on the role of the myeloid cell network, especially dendritic cells (DC) during tumor-targeted therapy.

METHODS

Here, we investigated therapy-mediated immunological alterations in the tumor microenvironment (TME) and tumor-draining lymph nodes (LN) in the D4M.3A preclinical melanoma mouse model (harboring the V-Raf murine sarcoma viral oncogene homolog B (BRAF)V600E mutation) by using high-dimensional multicolor flow cytometry in combination with multiplex immunohistochemistry. This was complemented with RNA sequencing and cytokine quantification to characterize the immune status of the tumors. The importance of T cells during tumor-targeted therapy was investigated by depleting CD4+ or CD8+ T cells in tumor-bearing mice. Tumor antigen-specific T-cell responses were characterized by performing in vivo T-cell proliferation assays and the contribution of conventional type 1 DC (cDC1) to T-cell immunity during tumor-targeted therapy was assessed using Batf3-/- mice lacking cDC1.

RESULTS

Our findings reveal that BRAF-inhibitor therapy increased tumor immunogenicity, reflected by an upregulation of genes associated with immune activation. The T cell-inflamed TME contained higher numbers of activated cDC1 and cDC2 but also inflammatory CCR2-expressing monocytes. At the same time, tumor-targeted therapy enhanced the frequency of migratory, activated DC subsets in tumor-draining LN. Even more, we identified a cDC2 population expressing the Fc gamma receptor I (FcγRI)/CD64 in tumors and LN that displayed high levels of CD40 and CCR7 indicating involvement in T cell-mediated tumor immunity. The importance of cDC2 is underlined by just a partial loss of therapy response in a cDC1-deficient mouse model. Both CD4+ and CD8+ T cells were essential for therapy response as their respective depletion impaired therapy success. On resistance development, the tumors reverted to an immunologically inert state with a loss of DC and inflammatory monocytes together with the accumulation of regulatory T cells. Moreover, tumor antigen-specific CD8+ T cells were compromised in proliferation and interferon-γ-production.

CONCLUSION

Our results give novel insights into the remodeling of the myeloid landscape by tumor-targeted therapy. We demonstrate that the transient immunogenic tumor milieu contains more activated DC. This knowledge has important implications for the development of future combinatorial therapies.

SEAMARK: phase II study of first-line encorafenib and cetuximab plus pembrolizumab for MSI-H/dMMR BRAFV600E-mutant mCRC

Patients with both BRAF V600E mutations and microsatellite instability-high (MSI-H)/mismatch repair-deficient (dMMR) metastatic colorectal cancer (mCRC) have poor prognosis. Currently, there are no specifically targeted first-line treatment options indicated for patients with mCRC whose tumors harbor both molecular aberrations. Pembrolizumab is a checkpoint inhibitor approved for the treatment of MSI-H/dMMR mCRC, and the BRAF inhibitor encorafenib, in combination with cetuximab, is approved for previously treated BRAF V600E-mutant mCRC. Combination of pembrolizumab with encorafenib and cetuximab may synergistically enhance antitumor activity in patients with BRAF V600E-mutant, MSI-H/dMMR mCRC. SEAMARK is a randomized phase II study comparing the efficacy of the combination of pembrolizumab with encorafenib and cetuximab versus pembrolizumab alone in patients with previously untreated BRAF V600E-mutant, MSI-H/dMMR mCRC.

Mi-2β promotes immune evasion in melanoma by activating EZH2 methylation

Recent development of new immune checkpoint inhibitors has been particularly successfully in cancer treatment, but still the majority patients fail to benefit. Converting resistant tumors to immunotherapy sensitive will provide a significant improvement in patient outcome. Here we identify Mi-2β as a key melanoma-intrinsic effector regulating the adaptive anti-tumor immune response. Studies in genetically engineered mouse melanoma models indicate that loss of Mi-2β rescues the immune response to immunotherapy in vivo. Mechanistically, ATAC-seq analysis shows that Mi-2β controls the accessibility of IFN-γ-stimulated genes (ISGs). Mi-2β binds to EZH2 and promotes K510 methylation of EZH2, subsequently activating the trimethylation of H3K27 to inhibit the transcription of ISGs. Finally, we develop an Mi-2β-targeted inhibitor, Z36-MP5, which reduces Mi-2β ATPase activity and reactivates ISG transcription. Consequently, Z36-MP5 induces a response to immune checkpoint inhibitors in otherwise resistant melanoma models. Our work provides a potential therapeutic strategy to convert immunotherapy resistant melanomas to sensitive ones.

PTEN-restoration abrogates brain colonisation and perivascular niche invasion by melanoma cells

BACKGROUND

Melanoma brain metastases (MBM) continue to be a significant clinical problem with limited treatment options. Highly invasive melanoma cells migrate along the vasculature and perivascular cells may contribute to residual disease and recurrence. PTEN loss and hyperactivation of AKT occur in MBM; however, a role for PTEN/AKT in perivascular invasion has not been described.

METHODS

We used in vivo intracranial injections of murine melanoma and bulk RNA sequencing of melanoma cells co-cultured with brain endothelial cells (brECs) to investigate brain colonisation and perivascular invasion.

RESULTS

We found that PTEN-null melanoma cells were highly efficient at colonising the perivascular niche relative to PTEN-expressing counterparts. PTEN re-expression (PTEN-RE) in melanoma cells significantly reduced brain colonisation and migration along the vasculature. We hypothesised this phenotype was mediated through vascular-induced TGFβ secretion, which drives AKT phosphorylation. Disabling TGFβ signalling in melanoma cells reduced colonisation and perivascular invasion; however, the introduction of constitutively active myristolated-AKT (myrAKT) restored overall tumour size but not perivascular invasion.

CONCLUSIONS

PTEN loss facilitates perivascular brain colonisation and invasion of melanoma. TGFβ-AKT signalling partially contributes to this phenotype, but further studies are needed to determine the complementary mechanisms that enable melanoma cells to both survive and spread along the brain vasculature.

Guidelines for DC preparation and flow cytometry analysis of mouse nonlymphoid tissues

This article is part of the Dendritic Cell Guidelines article series, which provides a collection of state-of-the-art protocols for the preparation, phenotype analysis by flow cytometry, generation, fluorescence microscopy and functional characterization of mouse and human dendritic cells (DC) from lymphoid organs and various nonlymphoid tissues. DC are sentinels of the immune system present in almost every mammalian organ. Since they represent a rare cell population, DC need to be extracted from organs with protocols that are specifically developed for each tissue. This article provides detailed protocols for the preparation of single-cell suspensions from various mouse nonlymphoid tissues, including skin, intestine, lung, kidney, mammary glands, oral mucosa and transplantable tumors. Furthermore, our guidelines include comprehensive protocols for multiplex flow cytometry analysis of DC subsets and feature top tricks for their proper discrimination from other myeloid cells. With this collection, we provide guidelines for in-depth analysis of DC subsets that will advance our understanding of their respective roles in healthy and diseased tissues. While all protocols were written by experienced scientists who routinely use them in their work, this article was also peer-reviewed by leading experts and approved by all coauthors, making it an essential resource for basic and clinical DC immunologists.

Vemurafenib induces a noncanonical senescence-associated secretory phenotype in melanoma cells which promotes vemurafenib resistance

More than one half melanoma patients have BRAF gene mutation. BRAF inhibitor vemurafenib is an effective medication for these patients. However, acquired resistance is generally inevitable, the mechanisms of which are not fully understood. Cell senescence and senescence-associated secretory phenotype (SASP) are involved in extensive biological functions. This study was designed to explore the possible role of senescent cells in vemurafenib resistance. The results showed that vemurafenib treatment induced BRAF-mutant but not wild-type melanoma cells into senescence, as manifested by positive β-galactosidase staining, cell cycle arrest, enlarged cellular morphology, and cyclin D1/p-Rb pathway inhibition. However, the senescent cells induced by vemurafenib (SenV) did not display DNA damage response, p53/p21 pathway activation, reactive oxygen species accumulation, decline of mitochondrial membrane potential, or secretion of canonical SASP cytokines. Instead, SenV released other cytokines, including CCL2, TIMP2, and NGFR, to protect normal melanoma cells from growth inhibition upon vemurafenib treatment. Xenograft experiments further confirmed that vemurafenib induced melanoma cells into senescence in vivo. The results suggest that vemurafenib can induce robust senescence in BRAF^V600E melanoma cells, leading to the release of resistance-conferring cytokines. Both the senescent cells and the resistant cytokines could be potential targets for tackling vemurafenib resistance.

Antigen presentation by clonally diverse CXCR5+ B cells to CD4 and CD8 T cells is associated with durable response to immune checkpoint inhibitors

Introduction

Increased T cell infiltration and interferon gamma (IFNγ) pathway activation are seen in tumors of melanoma patients who respond to ICI (immune checkpoint inhibitor) or MAPK pathway inhibitor (MAPKi) therapies. Yet, the rate of durable tumor control after ICI is almost twice that of MAPKi, suggesting that additional mechanisms may be present in patients responding to ICI therapy that are beneficial for anti-tumor immunity.

Methods

We used transcriptional analysis and clinical outcomes from patients treated with ICI or MAPKi therapies to delineate immune mechanisms driving tumor response.

Results

We discovered response to ICI is associated with CXCL13-driven recruitment of CXCR5+ B cells with significantly higher clonal diversity than MAPKi. Our in vitro data indicate that CXCL13 production was increased in human peripheral blood mononuclear cells by anti-PD1, but not MAPKi, treatment. Higher B cell infiltration and B cell receptor (BCR) diversity allows presentation of diverse tumor antigens by B cells, resulting in activation of follicular helper CD4 T cells (Tfh) and tumor reactive CD8 T cells after ICI therapy. Higher BCR diversity and IFNγ pathway score post-ICI are associated with significantly longer patient survival compared to those with either one or none.

Conclusions

Response to ICI, but not to MAPKi, depends on the recruitment of CXCR5+ B cells into the tumor microenvironment and their productive tumor antigen presentation to follicular helper and cytotoxic, tumor reactive T cells. Our study highlights the potential of CXCL13 and B cell based strategies to enhance the rate of durable response in melanoma patients treated with ICI.

Combination of immune-checkpoint inhibitors and targeted therapies for melanoma therapy: The more, the better?

The approval of immune-checkpoint inhibitors (CPI) and mitogen activated protein kinase inhibitors (MAPKi) in recent years significantly improved the treatment management and survival of patients with advanced malignant melanoma. CPI aim to counter-act receptor-mediated inhibitory effects of tumor cells and immunomodulatory cell types on effector T cells, whereas MAPKi are intended to inhibit tumor cell survival. In agreement with these complementary modes of action preclinical data indicated that the combined application of CPI and MAPKi or their optimal sequencing might provide additional clinical benefit. In this review the rationale and preclinical evidence that support the combined application of MAPKi and CPI either in concurrent or consecutive regimens are presented. Further, we will discuss the results from clinical trials investigating the sequential or combined application of MAPKi and CPI for advanced melanoma patients and their implications for clinical practice. Finally, we outline mechanisms of MAPKi and CPI cross-resistance which limit the efficacy of currently available treatments, as well as combination regimens.

Targeting the Molecular and Immunologic Features of Leiomyosarcoma

Leiomyosarcoma (LMS) is a rare, aggressive mesenchymal tumor with smooth muscle differentiation. LMS is one of the most common histologic subtypes of soft tissue sarcoma; it most frequently occurs in the extremities, retroperitoneum, or uterus. LMS often demonstrates aggressive tumor biology, with a higher risk of developing distant metastatic disease than most sarcoma histologic types. The prognosis is poor, particularly in patients with uterine disease, and there is a need for the development of more effective therapies. Genetically, LMS is karyotypically complex and characterized by a low tumor mutational burden, with frequent alterations in TP53, RB1, PTEN, and DNA damage response pathways that may contribute to resistance against immune-checkpoint blockade monotherapy. The LMS immune microenvironment is highly infiltrated with tumor-associated macrophages and tumor-infiltrating lymphocytes, which may represent promising biomarkers. This review provides an overview of the clinical and pathologic behavior of both soft tissue and uterine LMS and summarizes the genomic and immune characteristics of these tumors and how they may provide opportunities for the development of biomarker-based immune therapies.

Neoadjuvant plus adjuvant combined or sequenced vemurafenib, cobimetinib and atezolizumab in patients with high-risk, resectable BRAF-mutated and wild-type melanoma: NEO-TIM, a phase II randomized non-comparative study

Background

Following the increased survival of patients with metastatic melanoma thanks to immunotherapy and targeted therapy, neoadjuvant approaches are being investigated to address the unmet needs of unresponsive and intolerant patients. We aim to investigate the efficacy of neoadjuvant plus adjuvant combined or sequenced vemurafenib, cobimetinib and atezolizumab in patients with high-risk, resectable BRAF-mutated and wild-type melanoma.

Methods

The study is a phase II, open-label, randomized non-comparative trial in patients with stage IIIB/C/D surgically resectable, BRAF-mutated and wild-type melanoma, with three possible treatments: (1) vemurafenib 960 mg twice daily from day 1 to 42; (2) vemurafenib 720 mg twice daily from day 1 to 42; (3) cobimetinib 60 mg once daily from day 1 to 21 and from day 29 to 42; and (4) atezolizumab 840 mg for two cycles (day 22 and day 43).Patients will be randomized to three different arms: A) BRAF-mutated patients will receive over 6 weeks (1) + (3); B) BRAF-mutated patients will receive over 6 weeks (2) + (3) + (4); C) BRAF wild-type patients will receive over 6 weeks (3) + (4). All patients will also receive atezolizumab 1200 mg every 3 weeks for 17 cycles after surgery and after a second screening period (up to 6 weeks).

Discussion

Neoadjuvant therapy for regional metastases may improve operability and outcomes and facilitate the identification of biomarkers that can guide further lines of treatment. Patients with clinical stage III melanoma may especially benefit from neoadjuvant treatment, as the outcomes of surgery alone are very poor. It is expected that the combination of neoadjuvant and adjuvant treatment may reduce the incidence of relapse and improve survival.

Clinical trial registration

eudract.ema.europa.eu/protocol.htm, identifier 2018-004841-17.

Fucosylation of HLA-DRB1 regulates CD4+ T cell-mediated anti-melanoma immunity and enhances immunotherapy efficacy

Immunotherapy efficacy is limited in melanoma, and combinations of immunotherapies with other modalities have yielded limited improvements but also adverse events requiring cessation of treatment. In addition to ineffective patient stratification, efficacy is impaired by paucity of intratumoral immune cells (itICs); thus, effective strategies to safely increase itICs are needed. We report that dietary administration of L-fucose induces fucosylation and cell surface enrichment of the major histocompatibility complex (MHC)-II protein HLA-DRB1 in melanoma cells, triggering CD4+ T cell-mediated increases in itICs and anti-tumor immunity, enhancing immune checkpoint blockade responses. Melanoma fucosylation and fucosylated HLA-DRB1 associate with intratumoral T cell abundance and anti-programmed cell death protein 1 (PD1) responder status in patient melanoma specimens, suggesting the potential use of melanoma fucosylation as a strategy for stratifying patients for immunotherapies. Our findings demonstrate that fucosylation is a key mediator of anti-tumor immunity and, importantly, suggest that L-fucose is a powerful agent for safely increasing itICs and immunotherapy efficacy in melanoma.

Clinical Features Associated with Outcomes and Biomarker Analysis of Dabrafenib plus Trametinib Treatment in Patients with BRAF-Mutant Melanoma Brain Metastases

PURPOSE

This study aimed to identify baseline clinical features associated with the outcomes of patients enrolled in the COMBI-MB phase II study of dabrafenib and trametinib treatment in patients with V600 BRAF-mutant metastatic melanoma with melanoma brain metastases (MBM). Exploratory biomarker analysis was also conducted as part of the synergistic COMBI-BRV trial (BRV116521), to identify molecular and immunologic changes associated with dabrafenib in MBMs and extracranial metastases (ECM).

PATIENTS AND METHODS

Post hoc analysis was performed for baseline features of patients (n = 125) enrolled in COMBI-MB. Analyses were performed to identify baseline clinical features associated with intracranial response rate (ICRR), progression-free survival (PFS), and overall survival (OS).

Exploratory biomarker analysis was performed on biospecimen collected in the COMBI-BRV trial in which patients with BRAF-mutant, resectable MBM were treated with dabrafenib for 10 to 14 days prior to craniotomy. Accessible ECM were resected or biopsied at the time of craniotomy. Biospecimens underwent molecular and immunologic profiling for comparative analyses.

RESULTS

In COMBI-MB baseline treatment with corticosteroids was independently associated with lower ICRR [39% vs. 63%; OR, 0.323; 95 % confidence interval (CI), 0.105-0.996; P = 0.049] and shorter PFS (HR, 1.93; 95% CI, 1.06-3.51; P = 0.031). Additional significant associations identified in the multivariate analysis were improved PFS in patients with a BRAFV600E genotype (HR, 0.565; 95% CI, 0.321-0.996; P = 0.048) and improved OS in patients with Eastern Cooperative Oncology Group 0 (HR, 0.44; 95% CI, 0.25-0.78; P = 0.005).

CONCLUSIONS

Corticosteroid treatment was associated with reduced ICRR and PFS in COMBI-MB, similar to results with immunotherapy for MBMs. Baseline corticosteroid treatment is a key factor to consider in MBM patient management and clinical trial design/interpretation.

An Immunogenic Cell Death-Related Gene Signature Reflects Immune Landscape and Predicts Prognosis in Melanoma Independently of BRAF V600E Status

Immunogenic cell death (ICD) is a type of regulated cell death that can activate adaptive immune response, and its ability to reshape the tumor microenvironment via multiple mechanisms may contribute to immunotherapy. The treatment options for patients with skin cutaneous melanoma (SKCM) vary based on BRAF V600E statuses. However, all standard treatments include immunotherapy. Therefore, it is critical to identify ICD-associated signatures that can help classify patients according to benefits from ICD immunotherapy. In this study, data on melanoma samples with BRAF V600E mutation (BRAF V600E-mutant melanoma) and melanoma samples with wild-type BRAF V600E alleles (BRAF V600E WT melanoma) were collected from The Cancer Genome Atlas (TCGA) database. The ICD-related (ICD-high and ICD-low) subgroups of patients with BRAF V600E WT melanoma were established via consensus clustering. The analyses of survival, differentially expressed genes (DEGs), functional annotation, and immune landscape were performed in these two subgroups. Results showed that ICD-high subgroup was correlated with a positive overall survival (OS) and active tumor immune landscape. A model comprising seven prognosis ICD-related gene biomarkers was developed. Survival analysis and receiver operating characteristic (ROC) curve evaluation in both cohorts with BRAF V600E WT and BRAF V600E-mutant melanoma showed an accurate prognostic estimation of ICD-related risk signature. There was a correlation between immune cell infiltration and immunotherapy response and risk score. Thus, the ICD risk signature was closely associated with the tumor's immune microenvironment. Our results may provide insights to further individualize and improve precision therapeutic decision-making in BRAF V600E-mutant and WT melanoma.

Cancer Immunology and Immunotherapy: From Defining Basic Immunology to Leading the Fight Against Cancer

The past decade has seen the advent and widespread use of several immunotherapeutic modalities that have markedly improved treatment outcomes for patients with various cancers. Nevertheless, the study of cancer immunology traces its roots back to the inception of modern immunology, and played a critical role in the of discovery of central immunological concepts and development of key technologies and methodologies and that have propelled advances in all areas of immunology.

Loss of MHC-I antigen presentation correlated with immune checkpoint blockade tolerance in MAPK inhibitor-resistant melanoma

Immune checkpoint blockade and MAPK-targeted combined therapy is a promising regimen for advanced melanoma patients. However, the clinical benefit from this combo regimen remains limited, especially in patients who acquired resistance to MAPK-targeted therapy. Here, we systematically characterized the immune landscape during MAPK-targeted therapy in patients and mouse melanoma models. We observed that both the abundance of tumor-infiltrated T cells and the expression of immune-related genes were upregulated in the drug-responsive period, but downregulated in the resistance period, implying that acquired drug resistance dampens the antitumor immune response. Further transcriptomic dissection indicated that loss of MHC-I antigen presentation on tumor cells plays a critical role in the reduction of T cell infiltration during drug resistance. Survival analysis demonstrates that loss of antigen presentation and reduction of T-cell infiltration during acquired drug resistance are associated with poorer clinical response and prognosis of anti-PD-1 therapy in melanoma patients. In addition, we identified that alterations in the MAPK inhibitor resistance-related oncogenic signaling pathway closely correlated with deficiency of MHC-I antigen presentation, including activation of the PI3K-mTOR, MAPK, and Wnt pathways. In conclusion, our research illuminates that decreased infiltration of T cells is associated with acquired drug resistance during MAPK-targeted therapy, which may underlie the cross-resistance to immune checkpoint blockade.

Application of Noninvasive Imaging to Combined Immune Checkpoint Inhibitors for Breast Cancer: Facts and Future

With the application of mono-immunotherapy in cancer, particularly immune checkpoint inhibitors, improved outcomes have been achieved. However, there are several limitations to immunotherapy, such as a poor response to the drugs, immune resistance, and immune-related adverse events. In recent years, studies of preclinical animal models and clinical trials have demonstrated that immune checkpoint inhibitors for breast cancer can significantly prolong the overall survival and quality of patients' lives. Meanwhile, combined immune checkpoint inhibitor treatment has attracted researchers' attention and showed great potential in the comprehensive treatment of breast cancer patients. Additionally, noninvasive imaging enables physicians to predict response to combined immunotherapeutic drugs, achieve treatment efficacy, and lead to better clinical management. Herein, we review the background of combined immune checkpoint inhibitor therapy and summarize its targeted imaging as well as progress in noninvasive imaging aimed at evaluating therapeutic outcomes. Finally, we describe several factors that may influence the outcome of this combined immunotherapy, the future direction of medical imaging, and the potential application of artificial intelligence in breast cancer. With further development of noninvasive imaging for the guidance of combined immune checkpoint inhibitors, cures for this disease may be achieved.

CD137 agonist potentiates the abscopal efficacy of nanoparticle-based photothermal therapy for melanoma

Despite the promise of immunotherapy such as the immune checkpoint inhibitors (ICIs) anti-PD-1 and anti-CTLA-4 for advanced melanoma, only 26%-52% of patients respond, and many experience grade III/IV immune-related adverse events. Motivated by the need for an effective therapy for patients non-responsive to clinically approved ICIs, we have developed a novel nanoimmunotherapy that combines locally administered Prussian blue nanoparticle-based photothermal therapy (PBNP-PTT) with systemically administered agonistic anti-CD137 monoclonal antibody therapy (aCD137). PBNP-PTT was administered at various thermal doses to melanoma cells in vitro, and was combined with aCD137 in vivo to test treatment effects on melanoma tumor progression, animal survival, immunological protection against tumor rechallenge, and hepatotoxicity. When administered at a melanoma-specific thermal dose, PBNP-PTT elicits immunogenic cell death (ICD) in melanoma cells and upregulates markers associated with antigen presentation and immune cell co-stimulation in vitro. Consequently, PBNP-PTT eliminates primary melanoma tumors in vivo, yielding long-term tumor-free survival. However, the antitumor immune effects generated by PBNP-PTT cannot eliminate secondary tumors, despite significantly slowing their growth. The addition of aCD137 enables significant abscopal efficacy and improvement of survival, functioning through activated dendritic cells and tumor-infiltrating CD8⁺ T cells, and generates CD4⁺ and CD8⁺ T cell memory that manifests in the rejection of tumor rechallenge, with no long-term hepatotoxicity. This study describes for the first time a novel and effective nanoimmunotherapy combination of PBNP-PTT with aCD137 mAb therapy for melanoma.

BRAF inhibitors and their immunological effects in malignant melanoma

INTRODUCTION

The treatment of cutaneous melanoma has been revolutionised by the development of small molecule inhibitors targeting the MAPK pathway, including inhibitors of BRAF (BRAFi) and MEK (MEKi), and immune checkpoint blockade antibodies, occurring in tandem. Despite these advances, the 5-year survival rate for patients with advanced melanoma remains only around 50%. Although not designed to alter immune responses within the tumour microenvironment (TME), MAPK pathway inhibitors (MAPKi) exert a range of effects on the host immune compartment which may offer opportunities for therapeutic interventions.

AREAS COVERED

We review the effects of MAPKi especially BRAFi, on the TME, focussing on alterations in inflammatory cytokine secretion, the recruitment of immune cells and their functions, both during response to BRAFi treatment and as resistance develops. We outline potential combinations of MAPKi with established and experimental treatments.

EXPERT OPINION

MAPKi in combination or in sequence with established treatments such as checkpoint inhibitors, anti-angiogenic agents, or new therapies such as adoptive cell therapies, may augment their immunological effects, reverse tumour-associated immune suppression and offer the prospect of longer-lived clinical responses. Refining therapeutic tools at our disposal and embracing "old friends" in the melanoma treatment arsenal, alongside new target identification, may improve the chances of therapeutic success.

Neoadjuvant therapy for melanoma: new and evolving concepts

Effective systemic therapies, including targeted BRAF/MEK inhibition and immune checkpoint blockade, have significantly changed the treatment landscape for malignant melanoma. Specifically, there have been promising clinical trial findings associated with the use of neoadjuvant therapy for clinically node-positive and oligometastatic disease, conditions that have historically been managed with up-front surgical resection when possible. This review focuses on the burgeoning field of neoadjuvant therapy for melanoma. We review the rationale for this treatment approach, summarize completed and ongoing neoadjuvant clinical trials, and contextualize these findings within the growing body of knowledge about targeted and immune checkpoint therapy. Finally, we discuss future directions for neoadjuvant trials in melanoma, with particular focus on biomarker development, treatment effect modification, novel therapeutic regimens, and evolving surgical indications for regional and oligometastatic disease.

Enhancing Adoptive Cell Transfer with Combination BRAF-MEK and CDK4/6 Inhibitors in Melanoma

Despite the success of immune checkpoint inhibitors that target cytotoxic lymphocyte antigen-4 (CTLA-4) and programmed-cell-death-1 (PD-1) in the treatment of metastatic melanoma, there is still great need to develop robust options for patients who are refractory to first line immunotherapy. As such there has been a resurgence in interest of adoptive cell transfer (ACT) particularly derived from tumor infiltrating lymphocytes. Moreover, the addition of cyclin dependent kinase 4/6 inhibitors (CDK4/6i) have been shown to greatly extend duration of response in combination with BRAF-MEK inhibitors (BRAF-MEKi) in pre-clinical models of melanoma. We therefore investigated whether combinations of BRAF-MEK-CDK4/6i and ACT were efficacious in murine models of melanoma. Triplet targeted therapy of BRAF-MEK-CDK4/6i with OT-1 ACT led to sustained and robust anti-tumor responses in BRAFi sensitive YOVAL1.1. We also show that BRAF-MEKi but not CDK4/6i enhanced MHC Class I expression in melanoma cell lines in vitro. Paradoxically CDK4/6i in low concentrations of IFN-γ reduced expression of MHC Class I and PD-L1 in YOVAL1.1. Overall, this work provides additional pre-clinical evidence to pursue combination of BRAF-MEK-CDK4/6i and to combine this combination with ACT in the clinic.

Short-term treatment with multi-drug regimens combining BRAF/MEK-targeted therapy and immunotherapy results in durable responses in Braf-mutated melanoma

Targeted and immunotherapy regimens have revolutionized the treatment of advanced melanoma patients. Despite this, only a subset of patients respond durably. Recently, combination strategies of BRAF/MEK inhibitors with immune checkpoint inhibitor monotherapy (α-CTLA-4 or α-PD-1) have increased the rate of durable responses. Based on evidence from our group and others, these therapies appear synergistic, but at the cost of significant toxicity. We know from other treatment paradigms (e.g. hematologic malignancies) that combination strategies with multi-drug regimens (>4 drugs) are associated with more durable disease control. To better understand the mechanism of these improved outcomes, and to identify and prioritize new strategies for testing, we studied several multi-drug regimens combining BRAF/MEK targeted therapy and immunotherapy combinations in a Braf-mutant murine melanoma model (Braf^V600E/Pten^−/−). Short-term treatment with α-PD-1 and α-CTLA-4 monotherapies were relatively ineffective, while treatment with α-OX40 demonstrated some efficacy [17% of mice with no evidence of disease, (NED), at 60-days]. Outcomes were improved in the combined α-OX40/α-PD-1 group (42% NED). Short-term treatment with quadruplet therapy of immunotherapy doublets in combination with targeted therapy [dabrafenib and trametinib (DT)] was associated with excellent tumor control, with 100% of mice having NED after combined DT/α-CTLA-4/α-PD-1 or DT/α-OX40/α-PD-1. Notably, tumors from mice in these groups demonstrated a high proportion of effector memory T cells, and immunologic memory was maintained with tumor re-challenge. Together, these data provide important evidence regarding the potential utility of multi-drug therapy in treating advanced melanoma and suggest these models can be used to guide and prioritize combinatorial treatment strategies.

Chemokine Pathways in Cutaneous Melanoma: Their Modulation by Cancer and Exploitation by the Clinician

The incidence of cutaneous malignant melanoma is rising globally and is projected to continue to rise. Advances in immunotherapy over the last decade have demonstrated that manipulation of the immune cell compartment of tumours is a valuable weapon in the arsenal against cancer; however, limitations to treatment still exist. Cutaneous melanoma lesions feature a dense cell infiltrate, coordinated by chemokines, which control the positioning of all immune cells. Melanomas are able to use chemokine pathways to preferentially recruit cells, which aid their growth, survival, invasion and metastasis, and which enhance their ability to evade anticancer immune responses. Aside from this, chemokine signalling can directly influence angiogenesis, invasion, lymph node, and distal metastases, including epithelial to mesenchymal transition-like processes and transendothelial migration. Understanding the interplay of chemokines, cancer cells, and immune cells may uncover future avenues for melanoma therapy, namely: identifying biomarkers for patient stratification, augmenting the effect of current and emerging therapies, and designing specific treatments to target chemokine pathways, with the aim to reduce melanoma pathogenicity, metastatic potential, and enhance immune cell-mediated cancer killing. The chemokine network may provide selective and specific targets that, if included in current therapeutic regimens, harbour potential to improve outcomes for patients.

PD0325901, an ERK inhibitor, enhances the efficacy of PD-1 inhibitor in non-small cell lung carcinoma

ERK pathway regulated the programmed death ligand-1 (PD-L1) expression which was linked to the response of programmed death-1 (PD-1)/PD-L1 blockade therapy. So it is deducible that ERK inhibitor could enhance the efficacy of PD-1 inhibitor in cancer immunotherapy. In this study, PD0325901, an oral potent ERK inhibitor, strongly enhanced the efficacy of PD-1 antibody in vitro and in vivo models in non-small cell lung carcinoma (NSCLC) cells. Mechanistically, PD0325901 or shRNA-ERK1/2 significantly downregulated the PD-L1 expression in NSCLC cells and increased the CD3⁺ T cells infiltration and functions in tumor tissue. There was a positive correlation between the p-ERK1/2 expression and PD-L1 expression in patients with NSCLC. And the patients with low p-ERK1/2 expression were observed a high response rate of PD-1/PD-L1 blockage therapy. Our results demonstrate that PD0325901, an ERK inhibitor, can enhance the efficacy of PD-1 blockage against NSCLC in vitro and in vivo models. And the combination of ERK inhibitor such as PD0325901 and PD-1/PD-L1 blockage is a promising regimen and encouraged to be further confirmed in the treatment of patients with NSCLC.

Roles of CCL2-CCR2 Axis in the Tumor Microenvironment

Chemokines are a small family of cytokines that were first discovered as chemotactic factors in leukocytes during inflammation, and reports on the relationship between chemokines and cancer progression have recently been increasing. The CCL2-CCR2 axis is one of the major chemokine signaling pathways, and has various functions in tumor progression, such as increasing tumor cell proliferation and invasiveness, and creating a tumor microenvironment through increased angiogenesis and recruitment of immunosuppressive cells. This review discusses the roles of the CCL2-CCR2 axis and the tumor microenvironment in cancer progression and their future roles in cancer therapy.

Plasma proteome alterations by MAPK inhibitors in BRAFV600-mutated metastatic cutaneous melanoma

Approximately half of metastatic cutaneous melanomas (CM) harbor a mutation in the BRAF protooncogene, upregulating the mitogen-activated protein kinase (MAPK)-pathway. The development of inhibitors targeting the MAPK pathway (MAPKi), i.e., BRAF- and MEK-inhibitors (BRAFi and MEKi), have substantially improved the survival in BRAFV600E/K-mutated stage IV metastatic CM. However, most patients develop resistance to treatment and no predictive biomarkers exist in practice. This study aimed at discovering plasma proteome changes during treatment MAPKi in patients with metastatic (stage IV) CM. Matched plasma samples before (pre) and during treatment (trm) from 23 patients with stage IV CM, treated with BRAF-inhibitors (BRAFi) alone or BRAF- and MEK- inhibitors combined (BRAFi and MEKi), were collected and analyzed with targeted proteomics by proximity extension assays. Additionally, plasma from 9 patients treated with BRAFi and MEKi was analyzed with in-depth high-resolution isoelectric focusing liquid-chromatography mass-spectrometry proteomics. Alterations of plasma proteins involved in granzyme and interferon gamma pathways were detected in patients treated with BRAFi, and cell adhesion-, neutrophil degranulation-, and proteolysis pathways in patients treated with BRAFi and MEKi. Several proteins were associated with progression-free survival after MAPKi treatment. We show that the majority of the altered plasma proteins were traceable to BRAFV600E-mutant metastatic CM tissue at mRNA level in 154 patients from the TCGA, further strengthening their involvement in tumoral response to treatment. This wide screen of plasma proteins unravels proteins that may serve as predictive and/or prognostic biomarkers of MAPKi treatment, opening a window of opportunity for plasma biomarker discovery in MAPKi-treatment of BRAFV600-mutant metastatic CM.

Mismatch Repair (MMR) Gene Alteration and BRAF V600E Mutation Are Potential Predictive Biomarkers of Immune Checkpoint Inhibitors in MMR-Deficient Colorectal Cancer

BACKGROUND

Immune checkpoint inhibitor (ICI) therapy is highly effective in metastatic mismatch repair-deficient (MMR-D) colorectal cancer (CRC). In this study, we evaluated molecular and clinical predictors of ICI response in MMR-D CRC.

MATERIALS AND METHODS

Patient databases at four cancer institutions were queried. The Fisher exact test was performed to test the association of clinical and molecular markers. The Kaplan-Meier method was used to estimate progression-free survival (PFS) and compared by the log-rank test. Twelve- and 24-month PFS rates were compared by the Z test.

RESULTS

A total of 60 patients with CRC with MMR-D/microsatellite instability-high who previously received ICIs were identified. Patients with liver metastasis had a lower overall response rate as compared with other sites of metastasis (36.4% vs. 68.7%; p = .081). Patients with MLH1/PMS2 loss had worse 1-year and 2-year PFS rates compared with patients with MSH2/MSH6 loss (84.2% vs. 57.8% and 78.2% vs. 54.2%, respectively; p < .001). There were improved 1-year and 2-year PFS rates in patients with wild-type BRAF when compared with patients with BRAF V600E mutation (73.3% vs. 40%, and 73.3% vs. 26.7%; respectively; p < .001). Patients aged >65 had significantly worse PFS rates as compared with patients aged ≤65 (p < .001).

CONCLUSION

BRAF V600E mutation, MLH1 and/or PMS2 loss, as well as age >65 years and liver metastasis, may be predictive of duration of ICI response in patients with MMR-D CRC. Larger cohorts are needed to confirm our findings.

IMPLICATIONS FOR PRACTICE

The results of this study reveal clinically important biomarkers that potentially predict immune checkpoint inhibitor response in patients with mismatch repair-deficient colorectal cancer.

The prognostic and predictive impact of BRAF mutations in deficient mismatch repair/microsatellite instability-high colorectal cancer: systematic review/meta-analysis

Aims: The authors present a systematic review/meta-analysis of the impact of BRAF mutations on prognosis and immune checkpoint inhibitor (ICI) response in deficient mismatch repair/microsatellite instability-high colorectal cancer. Methods: Hazard ratios for overall survival and odds ratios for objective response rate to ICIs were calculated in BRAF-mutated versus BRAF wild-type patients. Results: After screening, nine and three studies, respectively, were included for analysis of prognosis (analysis A) and ICI response (analysis B). Analysis A showed worse overall survival in BRAF-mutated compared with BRAF wild-type stage I-IV patients (hazard ratio: 1.57; 95% CI: 1.23-1.99), and analysis B showed no difference in objective response rate (odds ratio: 1.04; 95% CI: 0.48-2.25). Conclusion: BRAF mutations are associated with worse overall survival but not differential response to ICIs in deficient mismatch repair/microsatellite instability-high colorectal cancer.

CCL2: An Important Mediator Between Tumor Cells and Host Cells in Tumor Microenvironment

Tumor microenvironment (TME) formation is a major cause of immunosuppression. The TME consists of a considerable number of macrophages and stromal cells that have been identified in multiple tumor types. CCL2 is the strongest chemoattractant involved in macrophage recruitment and a powerful initiator of inflammation. Evidence indicates that CCL2 can attract other host cells in the TME and direct their differentiation in cooperation with other cytokines. Overall, CCL2 has an unfavorable effect on prognosis in tumor patients because of the accumulation of immunosuppressive cell subtypes. However, there is also evidence demonstrating that CCL2 enhances the anti-tumor capability of specific cell types such as inflammatory monocytes and neutrophils. The inflammation state of the tumor seems to have a bi-lateral role in tumor progression. Here, we review works focusing on the interactions between cancer cells and host cells, and on the biological role of CCL2 in these processes.

Tumors, tumor therapies, autoimmunity and the eye

The eye as an immune privileged organ is mostly spared from (auto)immune attacks. Intraocular inflammation like autoimmune uveitis is a rare event. Nevertheless, tumor-related destructive autoimmune responses can affect the eye, as observed in the case of cancer- associated retinopathy (CAR), an autoantibody-mediated destruction of retinal cells induced by the ectopic expression of ocular antigens by peripheral tumors. The new tumor therapies targeting immune checkpoints to enhance anti-tumor responses can also induce autoimmune responses and result in autoimmune diseases even in immune privileged organs like the eyes. Even MEK/BRAF-inhibitor therapies using small molecules to block tumor-specific signal transduction molecules have turned out to not just inhibit tumor growth and survival and render tumors more susceptible for immune recognition, but to have additional toxic effects on non-dividing retinal cells, destroying and making them potential targets of autoimmunity.

Clinical efficacy of T-cell therapy after short-term BRAF-inhibitor priming in patients with checkpoint inhibitor-resistant metastatic melanoma

PURPOSE

Despite impressive response rates following adoptive transfer of autologous tumor-infiltrating lymphocytes (TILs) in patients with metastatic melanoma, improvement is needed to increase the efficacy and broaden the applicability of this treatment. We evaluated the use of vemurafenib, a small-molecule BRAF inhibitor with immunomodulatory properties, as priming before TIL harvest and adoptive T cell therapy in a phase I/II clinical trial.

METHODS

12 patients were treated with vemurafenib for 7 days before tumor excision and during the following weeks until TIL infusion. TILs were grown from tumor fragments, expanded in vitro and reinfused to the patient preceded by a lymphodepleting chemotherapy regimen and followed by interleukin-2 infusion. Extensive immune monitoring, tumor profiling and T cell receptor sequencing were performed.

RESULTS

No unexpected toxicity was observed, and treatment was well tolerated. Of 12 patients, 1 achieved a complete response, 8 achieved partial response and 3 achieved stable disease. A PR and the CR are ongoing for 23 and 43 months, respectively. In vitro anti-tumor reactivity was found in TILs from 10 patients, including all patients achieving objective response. Serum and tumor biomarker analyses indicate that baseline cytokine levels and the number of T cell clones may predict response to TIL therapy. Further, TCR sequencing suggested skewing of TCR repertoire during in vitro expansion, promoting certain low frequency clonotypes.

CONCLUSIONS

Priming with vemurafenib before infusion of TILs was safe and feasible, and induced objective clinical responses in this cohort of patients with checkpoint inhibitor-resistant metastatic melanoma. In this trial, vemurafenib treatment seemed to decrease attrition and could be considered to bridge the waiting time while TILs are prepared.

Blockade of the co-inhibitory molecule PD-1 unleashes ILC2-dependent antitumor immunity in melanoma

Group 2 innate lymphoid cells (ILC2s) are essential to maintain tissue homeostasis. In cancer, ILC2s can harbor both pro-tumorigenic and anti-tumorigenic functions, but we know little about their underlying mechanisms or whether they could be clinically relevant or targeted to improve patient outcomes. Here, we found that high ILC2 infiltration in human melanoma was associated with a good clinical prognosis. ILC2s are critical producers of the cytokine granulocyte-macrophage colony-stimulating factor, which coordinates the recruitment and activation of eosinophils to enhance antitumor responses. Tumor-infiltrating ILC2s expressed programmed cell death protein-1, which limited their intratumoral accumulation, proliferation and antitumor effector functions. This inhibition could be overcome in vivo by combining interleukin-33-driven ILC2 activation with programmed cell death protein-1 blockade to significantly increase antitumor responses. Together, our results identified ILC2s as a critical immune cell type involved in melanoma immunity and revealed a potential synergistic approach to harness ILC2 function for antitumor immunotherapies.

Combining BRAF/MEK Inhibitors with Immunotherapy in the Treatment of Metastatic Melanoma

The management and prognosis of BRAF-mutant metastatic melanoma have changed drastically following the introduction of immune checkpoint inhibitors and molecularly targeted agents. These treatment options present different mechanisms of action and toxicities but also totally distinct kinetics of their response, including a "relatively" short-lasting benefit in subsets of patients treated with BRAF/MEK inhibitors and a lower response rate in patients treated with immune checkpoint inhibitors. BRAF/MEK inhibitors, when administered prior to or concurrently with immune checkpoint inhibitors, at least transiently alter some immunosuppressive parameters of the tumor microenvironment and theoretically improve sensitivity to immunotherapy. Preclinical data from mouse models with oncogene-addicted melanoma confirmed this beneficial immune/targeted synergy and supported the clinical testing of combinations of BRAF/MEK inhibitors and immune checkpoint inhibitors to improve the activity of upfront anti-melanoma therapies. The first positive phase III results were published in 2020, and triggered the discussion about the benefits, the limitations, as well as the possible implications of combining or sequencing targeted therapies with immune checkpoint inhibitors in everyday practice. Beginning from the interplay of immune/targeted agents within the melanoma microenvironment, this review outlines available information from the retrospective experience up to the late-stage randomized evidence on combinatorial treatments. Many clinical trials are currently underway exploring open questions about optimal timing, new immune biomarkers, and eligible patient subsets for these immune/targeted regimens. Awaiting these results, decision making in the first-line setting for BRAF-mutant melanoma is still guided by the patients' characteristics and the biological aspects of melanoma.

Role of nuclear localization in the regulation and function of T-bet and Eomes in exhausted CD8 T cells

The transcription factors T-bet and Eomesodermin (Eomes) regulate CD8 T cell exhaustion through undefined mechanisms. Here, we show that the subcellular localization of T-bet and Eomes dictate their regulatory activity in exhausted T cells (T_EXs). T_EXs had a higher ratio of nuclear Eomes:T-bet than memory T cells (T_MEMs) during chronic lymphocytic choriomeningitis virus (LCMV) infection in preclinical cancer models and in human tumors. Biochemically, T-bet and Eomes compete for the same DNA sequences, including the Pdcd1 T-box. High nuclear T-bet strongly represses Pdcd1 transcription in T_MEM, whereas low nuclear T-bet in T_EX leads to a dominant effect of Eomes that acts as a weaker repressor of Pdcd1. Blocking PD-1 signaling in T_EXs increases nuclear T-bet, restoring stronger repression of Pdcd1, and driving T-bet-associated gene expression programs of chemotaxis, homing, and activation. These data identify a mechanism whereby the T-bet-Eomes axis regulates exhaustion through their nuclear localization, providing insights into how these transcription factors regulate T_EX biology.

McLane et al. demonstrate that T-bet and Eomes expression contributes to exhaustion, but also their nuclear localization, and therefore functional activity, plays a key role. PD-1 blockade restores nuclear T-bet and promotes T cell homing and activation through direct competition with Eomes at gene promoters, such as Pdcd1.

Prognostic Clinical and Radiographic Biomarkers for BRAF-Targeted Therapy in Advanced Melanoma

Agents blocking BRAF and MEK produce robust responses in patients with BRAF^V600 -mutated melanoma; however, more accurate clinical biomarkers are needed to predict prognosis. To explore this question, we retrospectively studied 158 patients with BRAF-mutated melanoma treated with BRAF with or without MEK inhibitors. We found that the number of distinct tumor sites upon initiation of targeted therapy was associated with decreased progression-free survival but had no effect on overall survival. Serum values of lactate dehydrogenase and absolute lymphocyte count to absolute neutrophil count ratio independently had the strongest association with both progression-free survival and overall survival. Using both of these markers can help stratify prognosis of patients with metastatic melanoma receiving targeted therapy.

Skin immunization for effective treatment of multifocal melanoma refractory to PD1 blockade and Braf inhibitors

Background

Despite the remarkable benefits associated with the interventional treatment of melanomas (and other solid cancers) with immune checkpoint and Braf inhibitors (Brafi), most patients ultimately progress on therapy. The presence of multifocal/disseminated disease in patients increases their mortality risk. Hence, the development of novel strategies to effectively treat patients with melanomas that are resistant to anti-PD1 mAb (αPD1) and/or Brafi, particularly those with multifocal/disseminated disease remains a major unmet clinical need.

Methods

Mice developing induced/spontaneous Braf^V600E/Pten^−/− melanomas were treated by cutaneous immunization with a DNA vaccine encoding the melanoma-associated antigen TRP2, with Brafi or αPD1 alone, or with a combination of these treatments. Tumor progression, tumor-infiltration by CD4⁺ and CD8⁺ T cells, and the development of TRP2-specific CD8⁺ T cells were then monitored over time.

Results

Vaccination led to durable antitumor immunity against PD1/Brafi-resistant melanomas in both single lesion and multifocal disease models, and it sensitized PD1-resistant melanomas to salvage therapy with αPD1. The therapeutic efficacy of the vaccine was associated with host skin-resident cells, the induction of a systemic, broadly reactive IFNγ⁺CD8⁺ T cell repertoire, increased frequencies of CD8⁺ TIL and reduced levels of PD1^hi/intCD8⁺ T cells. Extended survival was associated with improved TIL functionality, exemplified by the presence of enhanced levels of IFNγ⁺CD8⁺ TIL and IL2⁺CD4⁺ TIL.

Conclusions

These data support the use of a novel genetic vaccine for the effective treatment of localized or multifocal melanoma refractory to conventional αPD1-based and/or Brafi-based (immune)therapy.

PD-L1 blockade in combination with inhibition of MAPK oncogenic signaling in patients with advanced melanoma

Combining PD-L1 blockade with inhibition of oncogenic mitogen-activated protein kinase (MAPK) signaling may result in long-lasting responses in patients with advanced melanoma. This phase 1, open-label, dose-escalation and -expansion study (NCT02027961) investigated safety, tolerability and preliminary efficacy of durvalumab (anti–PD-L1) combined with dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor) for patients with BRAF-mutated melanoma (cohort A, n = 26), or durvalumab and trametinib given concomitantly (cohort B, n = 20) or sequentially (cohort C, n = 22) for patients with BRAF-wild type melanoma. Adverse events and treatment discontinuation rates were more common than previously reported for these agents given as monotherapy. Objective responses were observed in 69.2% (cohort A), 20.0% (cohort B) and 31.8% (cohort C) of patients, with evidence of improved tumor immune infiltration and durable responses in a subset of patients with available biopsy samples. In conclusion, combined MAPK inhibition and anti–PD-L1 therapy may provide treatment options for patients with advanced melanoma.

Immune checkpoints inhibitors or MAPK inhibitors are currently used as standard of care therapies for patients with advanced melanoma. Here the authors report a phase 1 clinical trial testing the anti-PD-L1 antibody durvalumab in combination with the BRAF inhibitor dafrafenib and the MEK inhibitor trametinib in patients with BRAFV600-mutant melanoma.

Rationale for Immune Checkpoint Inhibitors Plus Targeted Therapy in Metastatic Melanoma: A Review

Importance

In recent years, the management of metastatic melanoma has been transformed by the emergence of immune checkpoint inhibitors and targeted therapies that significantly improve patient survival. The complementary response kinetics of these treatment approaches, supported by mechanistic evidence that targeted therapy affects immune aspects of the tumor microenvironment, suggest that the optimal combination or sequencing of immune checkpoint inhibitors and targeted therapy may provide additional clinical benefit.

Observations

Clinical responses to BRAF and/or MEK inhibitors are associated with immune changes within the tumor microenvironment that have the potential to increase the sensitivity of BRAF V600-mutant melanoma to immune checkpoint inhibitors. The combination of immune checkpoint inhibitors with targeted therapy may therefore increase duration of response, improve tumor control, extend survival, and increase the proportion of patients experiencing durable benefit. A targeted therapy-immune checkpoint inhibitor sequencing approach may also be supported by this evidence, but clinical questions regarding optimal timing, duration, and patient selection remain.

Conclusions and Relevance

This review outlines the rationale and preclinical evidence that support immune checkpoint inhibitor plus targeted therapy combination and sequencing strategies in melanoma and highlights the results available to date from clinical trials exploring these approaches to treatment. Several late-stage trials are under way looking to answer open questions in this field and address the continuing debate surrounding up-front combination vs sequencing. As phase 3 data have begun to emerge, trial designs and available data from key studies are discussed in the context of their resultant implications for clinical practice.

BRAFV595E Mutation Associates CCL17 Expression and Regulatory T Cell Recruitment in Urothelial Carcinoma of Dogs

Regulatory T cells may serve as targets in cancer immunotherapy. A previous study showed that the chemokine CCL17 and the receptor CCR4 play roles in regulatory T cell recruitment in canine urothelial carcinoma. In this article, we show that the BRAF^V595E mutation is associated with tumor-produced CCL17 and regulatory T cell infiltration in dogs with urothelial carcinoma. In comparison with healthy dogs, dogs with urothelial carcinoma showed increased CCL17 mRNA expression in the bladder and elevated CCL17 protein concentration in urine. Immunohistochemistry showed increased levels of Foxp3⁺ regulatory T cells in the tumor tissues of urothelial carcinoma. The density of Foxp3⁺ regulatory T cells was positively correlated with CCL17 concentration in urine, indicating that CCL17 is involved in regulatory T cell recruitment. Moreover, tumor-infiltrating regulatory T cells and urine CCL17 concentration were associated with poor prognosis in dogs with urothelial carcinoma. The number of tumor-infiltrating regulatory T cells, CCL17 mRNA expression, and urine CCL17 concentration in cases with BRAF^V595E mutation were higher than those in cases with wild-type BRAF. In vitro, high CCL17 production was detected in a canine urothelial carcinoma cell line with BRAF^V595E mutation but not in an urothelial carcinoma cell line with wild-type BRAF. Dabrafenib, a BRAF inhibitor, decreased CCL17 production in the cell line with BRAF^V595E mutation. These results suggest that BRAF^V595E mutation induced CCL17 production and contributed to regulatory T cell recruitment in canine urothelial carcinoma.

Rapid recovery of postnivolumab vemurafenib-induced Drug Rash with Eosinophilia and Systemic Symptoms (DRESS) syndrome after tocilizumab and infliximab administration

Background

Immune checkpoint inhibitors such as nivolumab and targeted BRAF inhibitors have dramatically altered the treatment outcomes of metastatic melanoma over the past few years. Skin toxicity is the most common adverse event (AE) related to the commonly used BRAF inhibitor vemurafenib, affecting more than 90% of patients. Vemurafenib-related severe AEs with early onset are reported in patients who were previously treated with anti-programmed cell death-1 (anti PD-1) antibodies. A prolonged administration of systemic steroids is the first-line treatment of severe or life-threatening AEs. We report the case of a woman suffering from vemurafenib-related severe, rapidly worsening Drug Rash with Eosinophilia and Systemic Symptoms (DRESS) syndrome, resolved in a few hours after single-dose administration of a combination of TNF-α antagonist infliximab with interleukin (IL)-6 receptor antagonist tocilizumab.

Case presentation

A 41-year-old woman treated with single-agent nivolumab presented with a melanoma progression. Biopsy samples were revised, revealing a BRAF V600E mutation. The patient was started on vemurafenib and cobimetinib treatment only 10 days after the last administration of nivolumab. On the third day of anti-BRAF therapy, profound lymphopenia was detected, and maculopapular eruption appeared afterward. Subsequently, the clinical conditions deteriorated further, and the woman was admitted on an emergency basis with high fever, respiratory and cardiocirculatory failure, diffuse rash, generalized edema, and lymphadenopathy. Diagnosis of DRESS syndrome with overexpressed capillary leakage was made. A single dose of tocilizumab was administered with an improvement of cardiocirculatory and renal function in a few hours. Because of worsening of liver function, skin lesions and mucositis, a single dose of infliximab was prescribed, and dramatic improvement was noted over the next 24 hours. Dabrafenib and trametinib were initiated, and coinciding with washout of infliximab from the patient’s blood, the drug toxicity recurred.

Conclusion

Anti-IL-6 and anti-TNF-α target treatment of very severe AEs may afford an immediate resolution of potentially life-threatening symptoms and reduce the duration and the costs of hospitalization. Maintenance of therapeutic infliximab blood concentrations permits an early switch to dabrafenib after vemurafenib-related AEs.

Integrating Immunotherapy and Targeted Therapy in Cancer Treatment: Mechanistic Insights and Clinical Implications

Small-molecule targeted therapies have demonstrated outstanding potential in the clinic. These drugs are designed to minimize adverse effects by selectively attacking cancer cells while exerting minimal damage to normal cells. Although initial response to targeted therapies may be high, yielding positive response rates and often improving survival for an important percentage of patients, resistance often limits long-term effectiveness. On the other hand, immunotherapy has demonstrated durable results, yet for a limited number of patients. Growing evidence indicates that some targeted agents can modulate different components of the antitumor immune response. These include immune sensitization by inhibiting tumor cell-intrinsic immune evasion programs or enhancing antigenicity, as well as direct effects on immune effector and immunosuppressive cells. The combination of these two approaches, therefore, has the potential to result in synergistic and durable outcomes for patients. In this review, we focus on the latest advances on integrating immunotherapy with small-molecule targeted inhibitors. In particular, we discuss how specific oncogenic events differentially affect immune response, and the implications of these findings on the rational design of effective combinations of immunotherapy and targeted therapies.

Baseline immunity and impact of chemotherapy on immune microenvironment in cervical cancer

Background

We aimed to comprehensively evaluate the immunologic landscape at baseline and upon chemotherapy in cervical cancer. The information should aid ongoing clinical investigations of checkpoint blockade immunotherapies in this disease setting.

Methods

A series of 109 cervical carcinoma patients was retrospectively assayed before and after neoadjuvant chemotherapy. Tumour-infiltrating immune markers (CD3, CD4, CD8, CD20, CD56, CD68, PD-1, PD-L1) were assessed by immunohistochemistry. RNA sequencing analysis was performed on matched pre- and post-treatment fresh-frozen tissues.

Results

At diagnosis, diverse immune cell types including CD20+ B cells, CD3+ T cells, CD56+ natural killer (NK) cells, and CD68+ macrophages were detected in different proportions of cervical carcinoma. Unsupervised hierarchical clustering evidently showed that CD4+ and CD8+ T cell abundance correlated with PD-L1 expression. Based on the immune infiltration patterns, the patients could be stratified into four groups with prognostic relevance, namely, ‘immuno-active’, ‘immuno-medial’, ‘immuno-NK’, and ‘immuno-deficient’. Neoadjuvant chemotherapy was associated with increased CD4, CD8, CD20, and CD56 signals, most prominently in good responders. Transcriptomic data corroborated the improved anticancer immunity and identified immunosuppressive CD200 upregulation following chemotherapeutic intervention.

Conclusions

A subset of cervical cancer harbours active immune microenvironment, and chemotherapy treatment may further exert locoregional immunostimulation. Immune checkpoint inhibitors as combination or maintenance therapies warrant future exploration in clinic.

The emerging role of co-stimulatory molecules and their agonistic mAb-based combination therapies in melanoma

Although anti-PD-1/L1 and anti-CTLA-4 antibodies, the validated immune checkpoint blockades, can elicit durable long-lasting antitumor immunity and improve the clinical outcomes of melanoma treatment, there are still a fraction of patients who did not receive therapeutic benefits as expected. In addition to findings of blocking the co-inhibitory pathways, the preclinical and clinical evidence suggests that triggering the co-stimulatory pathways through agonists such as CD137, OX40, CD40, GITR and CD27 may be a rational next step for melanoma therapy. In this review, we discuss the progress of studies on these co-stimulatory molecules in terms of their promising therapeutic effects and underlying antitumor mechanisms, and provide a review of the possible combinations that orchestrate the interplay of co-stimulatory agonistic mAbs and other therapies for treating melanoma, including inhibitory immune checkpoint mAbs, adoptive T cell therapy, chemotherapy and radiotherapy. We also briefly present the limitations and challenges involved in these co-stimulatory agonistic mAb-based combination strategies for melanoma patients.

Targeted and immunotherapies in BRAF mutant melanoma: where we stand and what to expect

The therapeutic landscape for melanoma has evolved drastically in the past decade. Currently, immune checkpoint inhibitors and small-molecule inhibitors targeting the mitogen-activated protein kinase (MAPK) pathway are the two mainstay therapies for BRAF^V600 mutant advanced melanoma. Although MAPK dependence has been variably demonstrated in melanomas lacking BRAF^V600 mutations, definitive evidence of benefit with MAPK inhibitors has not been demonstrated. Thus, in the BRAF^V600 'wild-type' setting, immune checkpoint inhibitors are the standalone option(s). In the BRAF^V600 mutant setting, there is no definitive evidence prioritizing one therapeutic modality over another. Herein, we review the updated data of the pivotal phase III randomized controlled trials that established the standard-of-care first-line treatment for advanced melanoma, as it provides insights into long-term benefit, which is a major factor in therapy selection. We discuss the clinical considerations for choosing between these therapies in the front-line setting and beyond, specifically for patients with BRAF^V600 mutant melanoma based on currently available evidence. We have previously proposed a time-dependent resistance paradigm in which future therapeutic development strategies can be rooted. We also discuss how these Food and Drug Administration (FDA)-approved therapeutic modalities are being pursued earlier in the course of disease management, namely in adjuvant and neoadjuvant settings. FDA-approved interlesional oncolytic virotherapy in the modern era is also briefly discussed.

CRISPR/Cas9-mediated Knockout of SIRT6 Imparts Remarkable Antiproliferative Response in Human Melanoma Cells in vitro and in vivo

Melanoma is one of the most aggressive, potentially fatal forms of skin cancer and has been shown to be associated with solar ultraviolet radiation-dependent initiation and progression. Despite remarkable recent advances with targeted and immune therapeutics, lasting and recurrence-free survival remain significant concerns. Therefore, additional novel mechanism-based approaches are needed for effective melanoma management. The sirtuin SIRT6 appears to have a pro-proliferative function in melanocytic cells. In this study, we determined the effects of genetic manipulation of SIRT6 in human melanoma cells, in vitro and in vivo. Our data demonstrated that CRISPR/Cas9-mediated knockout (KO) of SIRT6 in A375 melanoma cells resulted in a significant (1) decrease in growth, viability and clonogenic survival and (2) induction of G1-phase cell cycle arrest. Further, employing a RT² Profiler PCR array containing 84 key transformation and tumorigenesis genes, we found that SIRT6 KO resulted in modulation of genes involved in angiogenesis, apoptosis, cellular senescence, epithelial-to-mesenchymal transition, hypoxia signaling and telomere maintenance. Finally, we found significantly decreased tumorigenicity of SIRT6 KO A375 cells in athymic nude mice. Our data provide strong evidence that SIRT6 promotes melanoma cell survival, both in vitro and in vivo, and could be exploited as a target for melanoma management.

BRAF Inhibitors: Molecular Targeting and Immunomodulatory Actions

The BRAF inhibitors vemurafenib, dabrafenib and encorafenib are used in the treatment of patients with BRAF-mutant melanoma. They selectively target BRAF kinase and thus interfere with the mitogen-activated protein kinase (MAPK) signalling pathway that regulates the proliferation and survival of melanoma cells. In addition to their molecularly targeted activity, BRAF inhibitors have immunomodulatory effects. The MAPK pathway is involved in T-cell receptor signalling, and interference in the pathway by BRAF inhibitors has beneficial effects on the tumour microenvironment and anti-tumour immune response in BRAF-mutant melanoma, including increased immune-stimulatory cytokine levels, decreased immunosuppressive cytokine levels, enhanced melanoma differentiation antigen expression and presentation of tumour antigens by HLA 1, and increased intra-tumoral T-cell infiltration and activity. These effects promote recognition of the tumour by the immune system and enhance anti-tumour T-cell responses. Combining BRAF inhibitors with MEK inhibitors provides more complete blockade of the MAPK pathway. The immunomodulatory effects of BRAF inhibition alone or in combination with MEK inhibition provide a rationale for combining these targeted therapies with immune checkpoint inhibitors. Available data support the synergy between these treatment approaches, indicating such combinations provide an additional beneficial effect on the tumour microenvironment and immune response in BRAF-mutant melanoma.

Tumor microenvironment and epithelial mesenchymal transition as targets to overcome tumor multidrug resistance

It is well established that multifactorial drug resistance hinders successful cancer treatment. Tumor cell interactions with the tumor microenvironment (TME) are crucial in epithelial-mesenchymal transition (EMT) and multidrug resistance (MDR). TME-induced factors secreted by cancer cells and cancer-associated fibroblasts (CAFs) create an inflammatory microenvironment by recruiting immune cells. CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSCs) and inflammatory tumor associated macrophages (TAMs) are main immune cell types which further enhance chronic inflammation. Chronic inflammation nurtures tumor-initiating/cancer stem-like cells (CSCs), induces both EMT and MDR leading to tumor relapses. Pro-thrombotic microenvironment created by inflammatory cytokines and chemokines from TAMs, MDSCs and CAFs is also involved in EMT and MDR. MDSCs are the most common mediators of immunosuppression and are also involved in resistance to targeted therapies, e.g. BRAF inhibitors and oncolytic viruses-based therapies. Expansion of both cancer and stroma cells causes hypoxia by hypoxia-inducible transcription factors (e.g. HIF-1α) resulting in drug resistance. TME factors induce the expression of transcriptional EMT factors, MDR and metabolic adaptation of cancer cells. Promoters of several ATP-binding cassette (ABC) transporter genes contain binding sites for canonical EMT transcription factors, e.g. ZEB, TWIST and SNAIL. Changes in glycolysis, oxidative phosphorylation and autophagy during EMT also promote MDR. Conclusively, EMT signaling simultaneously increases MDR. Owing to the multifactorial nature of MDR, targeting one mechanism seems to be non-sufficient to overcome resistance. Targeting inflammatory processes by immune modulatory compounds such as mTOR inhibitors, demethylating agents, low-dosed histone deacetylase inhibitors may decrease MDR. Targeting EMT and metabolic adaptation by small molecular inhibitors might also reverse MDR. In this review, we summarize evidence for TME components as causative factors of EMT and anticancer drug resistance.