Development of bispecific anti-c-Met/PD-1 diabodies for the treatment of solid tumors and the effect of c-Met binding affinity on efficacy

PD-1: A critical player and target for immune normalization

Immune system imbalances contribute to the pathogenesis of several different diseases, and immunotherapy shows great therapeutic efficacy against tumours and infectious diseases with immune-mediated derivations. In recent years, molecules targeting the programmed cell death protein 1 (PD-1) immune checkpoint have attracted much attention, and related signalling pathways have been studied clearly. At present, several inhibitors and antibodies targeting PD-1 have been utilized as anti-tumour therapies. However, increasing evidence indicates that PD-1 blockade also has different degrees of adverse side effects, and these new explorations into the therapeutic safety of PD-1 inhibitors contribute to the emerging concept that immune normalization, rather than immune enhancement, is the ultimate goal of disease treatment. In this review, we summarize recent advancements in PD-1 research with regard to immune normalization and targeted therapy.

Anti-Tumor Potential of Post-Translational Modifications of PD-1

Programmed cell death protein-1 (PD-1) is a vital immune checkpoint molecule. The location, stability, and protein-protein interaction of PD-1 are significantly influenced by post-translational modification (PTM) of proteins. The biological information of PD-1, including its gene and protein structures and the PD-1/PD-L1 signaling pathway, was briefly reviewed in this review. Additionally, recent research on PD-1 post-translational modification, including the study of ubiquitination, glycosylation, phosphorylation, and palmitoylation, was summarized, and research strategies for PD-1 PTM drugs were concluded. At present, only a part of PD-1/PD-L1 treated patients (35-45%) are benefited from immunotherapies, and novel strategies targeting PTM of PD-1/PD-L1 may be important for anti-PD-1/PD-L1 non-responders (poor responders).

Hepatocellular Carcinoma: Old and Emerging Therapeutic Targets

Liver cancer, predominantly hepatocellular carcinoma (HCC), globally ranks sixth in incidence and third in cancer-related deaths. HCC risk factors include non-viral hepatitis, alcohol abuse, environmental exposures, and genetic factors. No specific genetic alterations are unequivocally linked to HCC tumorigenesis. Current standard therapies include surgical options, systemic chemotherapy, and kinase inhibitors, like sorafenib and regorafenib. Immunotherapy, targeting immune checkpoints, represents a promising avenue. FDA-approved checkpoint inhibitors, such as atezolizumab and pembrolizumab, show efficacy, and combination therapies enhance clinical responses. Despite this, the treatment of hepatocellular carcinoma (HCC) remains a challenge, as the complex tumor ecosystem and the immunosuppressive microenvironment associated with it hamper the efficacy of the available therapeutic approaches. This review explores current and advanced approaches to treat HCC, considering both known and new potential targets, especially derived from proteomic analysis, which is today considered as the most promising approach. Exploring novel strategies, this review discusses antibody drug conjugates (ADCs), chimeric antigen receptor T-cell therapy (CAR-T), and engineered antibodies. It then reports a systematic analysis of the main ligand/receptor pairs and molecular pathways reported to be overexpressed in tumor cells, highlighting their potential and limitations. Finally, it discusses TGFβ, one of the most promising targets of the HCC microenvironment.

Acquired resistance to anti-PD1 therapy in patients with NSCLC associates with immunosuppressive T cell phenotype

Immune checkpoint inhibitor treatment has the potential to prolong survival in non-small cell lung cancer (NSCLC), however, some of the patients develop resistance following initial response. Here, we analyze the immune phenotype of matching tumor samples from a cohort of NSCLC patients showing good initial response to immune checkpoint inhibitors, followed by acquired resistance at later time points. By using imaging mass cytometry and whole exome and RNA sequencing, we detect two patterns of resistance¨: One group of patients is characterized by reduced numbers of tumor-infiltrating CD8+ T cells and reduced expression of PD-L1 after development of resistance, whereas the other group shows high CD8+ T cell infiltration and high expression of PD-L1 in addition to markedly elevated expression of other immune-inhibitory molecules. In two cases, we detect downregulation of type I and II IFN pathways following progression to resistance, which could lead to an impaired anti-tumor immune response. This study thus captures the development of immune checkpoint inhibitor resistance as it progresses and deepens our mechanistic understanding of immunotherapy response in NSCLC.

Genomic Mapping of Epidermal Growth Factor Receptor and Mesenchymal-Epithelial Transition-Up-Regulated Tumors Identifies Novel Therapeutic Opportunities

BACKGROUND

The identification of proteins in the cellular membrane of the tumoral cell is a key to the design of therapeutic agents. Recently, the bi-specific antibody amivantamab, targeting the oncogenic membrane proteins EGFR and MET, received regulatory approval for the treatment of adult patients with locally advanced or metastatic NSCLC.

METHODS

The authors interrogated several publicly available genomic datasets to evaluate the expression of both receptors and PD-L1 in most of the solid and hematologic malignancies and focused on prostate adenocarcinoma (PRAD) and pancreatic adenocarcinoma (PAAD).

RESULTS

In PAAD, EGFR highly correlated with PD-L1 and MET, and MET showed a moderate correlation with PD-L1, while in PRAD, EGFR, MET and PD-L1 showed a strong correlation. In addition, in tumors treated with immune checkpoint inhibitors, including anti-PD(L)1 and anti-CTLA4, a high expression of EGFR and MET predicted detrimental survival. When exploring the relationship of immune populations with these receptors, the authors observed that in PAAD and PRAD, EGFR moderately correlated with CD8+ T cells. Furthermore, EGFR and MET correlated with neutrophils in PRAD.

CONCLUSIONS

The authors identified tumor types where EGFR and MET were highly expressed and correlated with a high expression of PD-L1, opening the door for the future combination of bi-specific EGFR/MET antibodies with anti-PD(L)1 inhibitors.

Low co-expression of PD-L1 and oncogenic receptor tyrosine kinases HER2 and cMET in urothelial carcinoma is associated with discordant expression between primary and metastatic sites

OBJECTIVES

Novel regimens targeting immune checkpoints and the cMET or HER2 pathways are under investigation in metastatic urothelial carcinoma (mUC) though co-expression of these molecular targets has not been defined. We sought to characterize the protein co-expression rates of PD-L1, cMET and HER2 in primary and metastatic mUC lesions and agreement rates in paired biopsies.

MATERIALS AND METHODS

We assessed PD-L1, cMET and HER2 protein expression by immunohistochemistry (IHC) in archival mUC samples identified from an institutional database (n = 143). Correlation of expression between primary and metastatic biopsies was performed in patients with available paired biopsies (n = 79). Protein expression levels by predefined thresholds were measured, and Cohen's kappa statistics (κ) were utilized to assess the agreement in expression between paired primary and metastatic samples.

RESULTS

In primary tumors (n = 85), high expression of PD-L1, cMET, and HER2 was observed in 14.1%, 34.1%, and 12.9%, respectively. In metastatic samples (n = 143), high expression of PD-L1, cMET and HER2 was detected in 9.8%, 41.3%, and 9.8%, respectively. Expression agreement rates between paired specimens (n = 79) were PD-L1: 79.7% (κ = 0.09), cMET: 69.6% (κ = 0.35), HER2: 84.8% (κ = 0.17). High PD-L1/cMET co-expression was observed in only 5.1% (n = 4) of primary and 4.9% (n = 7) of metastatic specimens. High co-expression of PD-L1/HER2 occurred in 3.8% (n = 3) of primary samples and no metastatic samples. The overall co-expression agreement between paired samples was 55.7% (κ = 0.22) for PD-L1/cMET and 67.1% (κ = 0.06) for PD-L1/HER2, but agreement for high co-expression between paired samples was very low (2.5% for PD-L1/cMET and 0% for PD-L1/HER2).

CONCLUSIONS

Tumor co-expression of high cMET or HER2 and PD-L1 is low in this cohort. Agreement of high co-expression between primary and metastatic sites is rare. Biomarker-based strategies used in selection of patients for contemporary trials testing combinations of immune checkpoint inhibitors with either cMET or HER2-targeted agents should account for discordant biomarker expression between primary and metastatic sites.

Targeting MET: Discovery of Small Molecule Inhibitors as Non-Small Cell Lung Cancer Therapy

MET has been considered as a promising drug target for the treatment of MET-dependent diseases, particularly non-small cell lung cancer (NSCLC). Small molecule MET inhibitors with mainly three types of binding modes (Ia/Ib, II, and III) have been developed. In this Review, we provide an overview of the structural features, activation mechanism, and dysregulation pathway of MET and summarize progress on the development and discovery strategies utilized for MET inhibitors as well as mechanisms of acquired resistance to current approved inhibitors. The insights will accelerate discovery of new generation MET inhibitors to overcome clinical acquired resistance.

Targeting the cMET pathway to enhance immunotherapeutic approaches for mUM patients

The liver is the most preferential initial site of metastasis for uveal melanoma (mUM), and this preference is associated with rapid mortality in mUM patients. Despite the significant clinical benefits of Immune checkpoint inhibitors (ICIs) in metastatic cutaneous melanoma patients, ICIs have shown little to no benefit in mUM patients. A potential reason for this inefficiency of ICI could be partly devoted to the involvement of the liver itself, thanks to its rich source of growth factors and immunosuppressive microenvironment. Uveal melanoma cells show increased expression of a transmembrane protein called cMET, which is known as the sole receptor for the Hepatocyte growth factor (HGF). Hyperactivation of cMET by HGF contributes to mUM development, and the liver, being the major source of HGF, may partially explain the metastasis of uveal melanoma cells to the liver. In addition, cMET/HGF signaling has also been shown to mediate resistance to ICI treatment, directly and indirectly, involving tumor and immune cell populations. Therefore, targeting the cMET/HGF interaction may enhance the efficacy of immunotherapeutic regimes for mUM patients. Hence in this minireview, we will discuss the rationale for combining cMET inhibitors/antibodies with leading immune checkpoint inhibitors for treating mUM. We will also briefly highlight the challenges and opportunities in targeting cMET in mUM.

Heart failure and cancer: From active exposure to passive adaption

The human body seems like a "balance integrator." On the one hand, the body constantly actively receives various outside stimuli and signals to induce changes. On the other hand, several internal regulations would be initiated to adapt to these changes. In most cases, the body could keep the balance in vitro and in vivo to reach a healthy body. However, in some cases, the body can only get to a pathological balance. Actively exposed to unhealthy lifestyles and passively adapting to individual primary diseases lead to a similarly inner environment for both heart failure and cancer. To cope with these stimuli, the body must activate the system regulation mechanism and face the mutual interference. This review summarized the association between heart failure and cancer from active exposure to passive adaption. Moreover, we hope to inspire researchers to contemplate these two diseases from the angle of overall body consideration.

Mesenchymal Epithelial Transition Factor (MET): A Key Player in Chemotherapy Resistance and an Emerging Target for Potentiating Cancer Immunotherapy

The MET protein is a cell surface receptor tyrosine kinase predominately expressed in epithelial cells. Upon binding of its only known ligand, hepatocyte growth factor (HGF), MET homodimerizes, phosphorylates, and stimulates intracellular signalling to drive cell proliferation. Amplification or hyperactivation of MET is frequently observed in various cancer types and it is associated with poor response to conventional and targeted chemotherapy. More recently, emerging evidence also suggests that MET/HGF signalling may play an immunosuppressive role and it could confer resistance to cancer immunotherapy. In this review, we summarized the preclinical and clinical evidence of MET's role in drug resistance to conventional chemotherapy, targeted therapy, and immunotherapy. Previous clinical trials investigating MET-targeted therapy in unselected or MET-overexpressing cancers yielded mostly unfavourable results. More recent clinical studies focusing on MET exon 14 alterations and MET amplification have produced encouraging treatment responses to MET inhibitor therapy. The translational relevance of MET inhibitor therapy to overcome drug resistance in cancer patients is discussed.

Combination strategies with PD-1/PD-L1 blockade: current advances and future directions

Antibodies targeting programmed cell death protein-1 (PD-1) or its ligand PD-L1 rescue T cells from exhausted status and revive immune response against cancer cells. Based on the immense success in clinical trials, ten α-PD-1 (nivolumab, pembrolizumab, cemiplimab, sintilimab, camrelizumab, toripalimab, tislelizumab, zimberelimab, prolgolimab, and dostarlimab) and three α-PD-L1 antibodies (atezolizumab, durvalumab, and avelumab) have been approved for various types of cancers. Nevertheless, the low response rate of α-PD-1/PD-L1 therapy remains to be resolved. For most cancer patients, PD-1/PD-L1 pathway is not the sole speed-limiting factor of antitumor immunity, and it is insufficient to motivate effective antitumor immune response by blocking PD-1/PD-L1 axis. It has been validated that some combination therapies, including α-PD-1/PD-L1 plus chemotherapy, radiotherapy, angiogenesis inhibitors, targeted therapy, other immune checkpoint inhibitors, agonists of the co-stimulatory molecule, stimulator of interferon genes agonists, fecal microbiota transplantation, epigenetic modulators, or metabolic modulators, have superior antitumor efficacies and higher response rates. Moreover, bifunctional or bispecific antibodies containing α-PD-1/PD-L1 moiety also elicited more potent antitumor activity. These combination strategies simultaneously boost multiple processes in cancer-immunity cycle, remove immunosuppressive brakes, and orchestrate an immunosupportive tumor microenvironment. In this review, we summarized the synergistic antitumor efficacies and mechanisms of α-PD-1/PD-L1 in combination with other therapies. Moreover, we focused on the advances of α-PD-1/PD-L1-based immunomodulatory strategies in clinical studies. Given the heterogeneity across patients and cancer types, individualized combination selection could improve the effects of α-PD-1/PD-L1-based immunomodulatory strategies and relieve treatment resistance.