Marengo Therapeutics: Pioneering T Cell Engagement for Cancer

Cancer immunotherapy has transformed treatment by harnessing the immune system to fight tumors. However, many current strategies face challenges such as limited efficacy, off-target effects, and resistance. Addressing these issues requires innovative methods to enhance T cell responses while maintaining precision in targeting cancer cells.

Marengo Therapeutics is advancing a novel T cell engagement approach to improve specificity and durability in anti-tumor responses. Their platform optimizes how T cells recognize and attack cancer, potentially leading to more effective treatments with fewer side effects.

T Cell Activation Mechanisms

T cell activation determines the immune system’s ability to recognize and eliminate abnormal cells, including cancerous ones. This process begins when a T cell receptor (TCR) binds to an antigen presented by major histocompatibility complex (MHC) molecules on antigen-presenting cells (APCs). The strength and duration of this interaction influence whether a T cell becomes fully activated or remains quiescent. High-affinity interactions lead to robust activation, but overly strong binding can induce T cell exhaustion, impairing function.

Once the TCR engages with an antigen-MHC complex, intracellular signaling cascades initiate through the CD3 complex, which contains immunoreceptor tyrosine-based activation motifs (ITAMs). These motifs recruit kinases such as Lck and ZAP-70, which phosphorylate downstream molecules, activating transcription factors like NF-κB, NFAT, and AP-1. These transcription factors drive T cell proliferation, cytokine production, and effector function. Regulatory proteins, including phosphatases like SHP-1 and SHP-2, modulate these signals to prevent excessive immune responses.

The immunological synapse, a specialized interface between the T cell and APC, further regulates activation. This synapse includes the central supramolecular activation cluster (cSMAC), where TCRs and co-receptors aggregate, and the peripheral supramolecular activation cluster (pSMAC), which contains adhesion molecules that stabilize the interaction. A stable immunological synapse is necessary for sustained signaling and full T cell activation. Disruptions, whether due to genetic mutations or tumor-derived inhibitory signals, can impair function and reduce response effectiveness.

Co-Stimulatory Pathways

T cell activation requires more than antigen recognition through the TCR; it also depends on co-stimulatory pathways, which determine whether a T cell fully activates, proliferates, and exerts effector functions. Without these secondary signals, T cells may enter a state of anergy, rendering them unresponsive even in the presence of their antigen.

The primary co-stimulatory interaction occurs between CD28 on T cells and its ligands, CD80 (B7-1) and CD86 (B7-2), found on APCs. This interaction amplifies early TCR signaling, enhancing calcium flux, Akt activation, and IL-2 production, all necessary for sustained responses.

Other co-stimulatory molecules further refine T cell activation. Inducible co-stimulator (ICOS) supports follicular helper T cell differentiation, engaging with ICOS ligand (ICOS-L) on dendritic cells and B cells to promote cytokine secretion and survival signals. The 4-1BB (CD137) receptor enhances T cell expansion and memory formation when bound to its ligand 4-1BBL, activating TRAF-dependent signaling cascades that improve metabolic fitness.

OX40 (CD134) influences T cell longevity and resistance to apoptosis. Binding to OX40 ligand (OX40L) enhances NF-κB and PI3K/Akt signaling, increasing inflammatory cytokine production and prolonged survival. Agonistic OX40 antibodies have shown potential in reinvigorating exhausted T cells in tumors. Similarly, the GITR (glucocorticoid-induced TNFR-related protein) pathway modulates both effector and regulatory T cell activity, shifting immune balance toward a pro-inflammatory state.

Receptor Engineering For Targeted Therapies

Advancements in receptor engineering have expanded targeted cancer therapies, improving precision in distinguishing malignant cells from healthy tissues. Modified T cell receptors (TCRs) and chimeric antigen receptors (CARs) enhance selective tumor recognition. Unlike native TCRs, which rely on MHC molecules for antigen recognition, engineered CARs directly engage surface proteins on cancer cells, bypassing MHC restrictions that often limit therapeutic efficacy. This adaptability has led to the success of CAR-T cell therapies, particularly in hematologic malignancies targeting CD19 and BCMA.

Engineered receptors are further refined through structural modifications optimizing binding affinity, stability, and signal transduction. Adjusting the extracellular binding domain of CARs improves antigen recognition while minimizing off-target interactions. Affinity tuning reduces unintended activation against low-expressing normal tissues, improving safety in solid tumors. Additionally, modifications in intracellular signaling domains, such as incorporating co-stimulatory elements like 4-1BB or CD28, enhance persistence and functional potency. Studies indicate 4-1BB-based CARs promote long-term T cell survival and memory formation, while CD28-containing constructs drive more immediate responses.

Novel receptor engineering strategies address tumor heterogeneity and immune evasion. Synthetic Notch (synNotch) receptors enable context-dependent T cell activation, reducing off-target toxicity while enhancing localized effects. Dual-targeting CARs, which require recognition of two tumor-associated antigens before activation, mitigate antigen escape, a common mechanism of resistance. Logic-gated CARs integrate multiple signaling inputs to refine activation thresholds, ensuring tumor specificity without collateral damage to normal tissues.

Tumor Microenvironment Factors

The tumor microenvironment (TME) significantly influences cancer progression, shaping tumor growth and therapeutic resistance. This ecosystem consists of malignant cells, stromal components, extracellular matrix (ECM), and signaling molecules that create conditions favorable for tumor survival. One defining feature is its altered metabolic landscape, where cancer cells outcompete surrounding tissues for nutrients like glucose and glutamine. This metabolic reprogramming leads to lactate accumulation, creating an acidic microenvironment that promotes invasion and metastasis while impairing immune function. Studies link lactate buildup to increased tumor aggressiveness, making pH modulation a growing therapeutic focus.

The TME’s structural composition further complicates treatment. Dense ECM components, including collagen and fibronectin, create physical barriers that limit drug penetration. This fibrotic remodeling is particularly pronounced in desmoplastic tumors such as pancreatic ductal adenocarcinoma, where stromal stiffness correlates with poorer outcomes. Efforts to target ECM remodeling enzymes like matrix metalloproteinases (MMPs) and lysyl oxidase (LOX) aim to enhance drug distribution and improve responses. Additionally, abnormal tumor vasculature results in inconsistent oxygen and nutrient supply, fostering hypoxic regions that drive genetic instability and treatment resistance.

Marengo’s T Cell Engagement Platform

Marengo Therapeutics has developed a platform refining T cell engagement to enhance cancer treatment. Unlike conventional immunotherapies that rely on broad immune activation, Marengo’s approach selectively engages specific T cell populations, improving efficacy while minimizing off-target effects. Their method leverages precision receptor targeting to activate tumor-reactive T cells without inducing widespread immune overstimulation, addressing a challenge that has limited earlier immunotherapies. By fine-tuning T cell interactions with malignant cells, this platform sustains anti-tumor activity over extended periods, countering immune exhaustion and resistance.

A key feature of Marengo’s platform is its proprietary receptor-targeting strategy. Unlike traditional monoclonal antibodies or checkpoint inhibitors that broadly modulate immune checkpoints, this approach selectively activates tumor-specific T cells through unique antigen-receptor interactions. The platform enhances T cell persistence and functionality by optimizing co-stimulatory signaling while avoiding overstimulation that could lead to depletion. This control allows for a more durable response against tumors, particularly in cancers resistant to immune-based treatments. Preclinical data suggest this strategy may improve treatment durability and reduce relapse rates by maintaining an active population of tumor-targeting T cells, offering a potential breakthrough in cancer immunotherapy.