Improved therapeutic index of an acidic pH-selective antibody

Notch-Targeted Therapeutic in Colorectal Cancer by Notch1 Attenuation Via Tumor Microenvironment-Responsive Cascade DNA Delivery

The Notch signaling is a key molecular pathway that regulates cell fate and development. Aberrant Notch signaling can lead to carcinogenesis and progression of malignant tumors. However, current therapies targeting Notch pathway lack specificity and induce high toxicity. In this report, a tumor microenvironment-responsive and injectable hydrogel is designed to load plasmid DNA complexes as a cascade gene delivery system to achieve precise Notch-targeted gene therapy of colorectal cancer (CRC). The hydrogels are prepared through cross-linking between phenylboric acid groups containing poly(oligo(ethylene glycol)methacrylate) (POEGMA) and epigallocatechin gallate (EGCG), used to load the complexes between plasmid DNA encoding short hairpin RNAs of Notch1 (shNotch1) and fluorinated polyamidoamine (PAMAM-F) (PAMAM-F/shNotch1). In response to low pH and H2O2 in tumor microenvironment, the hydrogel can be dissociated and release the complexes for precise delivery of shNotch1 into tumor cells and inhibit Notch1 activity to suppress malignant biological behaviors of CRC. In the subcutaneous tumor model of CRC, PAMAM-F/shNotch1-loaded hydrogels can accurately attenuate Notch1 activity and significantly inhibit tumor growth without affecting Notch signal in adjacent normal tissues. Therefore, this therapeutic system can precisely inhibit Notch1 signal in CRC with high responsiveness and low toxicity, providing a promising Notch-targeted gene therapeutic for human malignancy.

Conditionally Active, pH-Sensitive Immunoregulatory Antibodies Targeting VISTA and CTLA-4 Lead an Emerging Class of Cancer Therapeutics

Immune checkpoints and other immunoregulatory targets can be difficult to precisely target due to expression on non-tumor immune cells critical to maintaining immune homeostasis in healthy tissues. On-target/off-tumor binding of therapeutics results in significant pharmacokinetic and pharmacodynamic problems. Target-mediated drug disposition (TMDD) significantly limits effective intratumoral drug levels and adversely affects anti-tumor efficacy. Target engagement outside the tumor environment may lead to severe immune-related adverse events (irAEs), resulting in a narrowing of the therapeutic window, sub-optimal dosing, or cessation of drug development altogether. Overcoming these challenges has become tractable through recent advances in antibody engineering and screening approaches. Here, we review the discovery and development of conditionally active antibodies with minimal binding to target at physiologic pH but high-affinity target binding at the low pH of the tumor microenvironment by focusing on the discovery and improved properties of pH-dependent mAbs targeting two T cell checkpoints, VISTA and CTLA-4.

Comparative Performance of High-Throughput Methods for Protein pKa Predictions

The medically relevant field of protein-based therapeutics has triggered a demand for protein engineering in different pH environments of biological relevance. In silico engineering workflows typically employ high-throughput screening campaigns that require evaluating large sets of protein residues and point mutations by fast yet accurate computational algorithms. While several high-throughput pKa prediction methods exist, their accuracies are unclear due to the lack of a current comprehensive benchmarking. Here, seven fast, efficient, and accessible approaches including PROPKA3, DeepKa, PKAI, PKAI+, DelPhiPKa, MCCE2, and H++ were systematically tested on a nonredundant subset of 408 measured protein residue pKa shifts from the pKa database (PKAD). While no method outperformed the null hypotheses with confidence, as illustrated by statistical bootstrapping, DeepKa, PKAI+, PROPKA3, and H++ had utility. More specifically, DeepKa consistently performed well in tests across multiple and individual amino acid residue types, as reflected by lower errors, higher correlations, and improved classifications. Arithmetic averaging of the best empirical predictors into simple consensuses improved overall transferability and accuracy up to a root-mean-square error of 0.76 pKa units and a correlation coefficient (R2) of 0.45 to experimental pKa shifts. This analysis should provide a basis for further methodological developments and guide future applications, which require embedding of computationally inexpensive pKa prediction methods, such as the optimization of antibodies for pH-dependent antigen binding.

Cancer metabolism within tumor microenvironments

BACKGROUND

Tumor microenvironments could determine cancer heterogeneity and malignancy. Hypoxia, nutrition starvation, and acidic pH could contribute to cancer malignancy associated with genetic, epigenetic, and metabolic alterations, promoting invasion and metastasis. Cancer cells adapting to extreme tumor microenvironments could enable evasion of cell death and immune responses. It could stimulate drug resistance and recurrence, resulting in poor patient prognosis. Therefore, investigating druggable targets of the malignant cancer cells within tumor microenvironments is necessary, but such treatments are limited. Cell-cell metabolic interaction may also contribute to cancer malignancy within the tumor microenvironments. Organelle-organelle interactions have recently gained attention as new cancer therapy targets as they play essential roles in the metabolic adaptation to the tumor microenvironment. In this review, we overview (1) metabolic alterations within tumor microenvironments, (2) cell-to-cell, and (3) organelle-to-organelle metabolic interactions, and we add novel insights into cancer therapy.

Metabolic adaptations of cancer in extreme tumor microenvironments

Cancer cells are highly heterogeneous to adapt to extreme tumor microenvironments (TMEs). TMEs challenge cancer cells via hypoxia, nutrition starvation, and acidic pH, promoting invasion and metastasis concomitant with genetic, epigenetic, and metabolic alterations. Metabolic adaptation to an extreme TME could allow cancer cells to evade cell death and immune responses, as well as resulting in drug resistance, recurrence, and poor patient prognosis. Therefore, elucidation of the metabolic adaptation of malignant cancer cells within TMEs is necessary, however, most are still elusive. Recently, adaptation of cancer cells within the TME can be analyzed via cell-cell interactions at the single-cell level. In addition, information into organelle-organelle interactions has recently been obtained. These cell-cell, and organelle-organelle interactions demonstrate the potential as new cancer therapy targets, as they play essential roles in the metabolic adaptation of cancer cells to the TME. In this manuscript, we review (1) metabolic adaptations within tumor microenvironments through (2) cell-to-cell, and (3) organelle-organelle metabolic interactions.

Engineering antibodies for conditional activity in the solid tumor microenvironment

Antibody-based therapeutics enjoy considerable clinical and commercial successes as cancer treatments. However, they can also cause serious toxicities due to recognition of tumor-associated antigens in noncancerous tissues, which can prevent antibody use in certain patient populations and therapeutic modalities. Here, we discuss recent efforts to develop advanced antibody therapeutics with activities restricted to the solid tumor microenvironment. With the intent of decreasing toxicities and expanding therapeutic windows, protein engineering strategies can render ligand binding sensitive to multiple tumor-specific characteristics. These triggers can be intrinsic to solid tumor microenvironments, such as low pH, high extracellular ATP, and the presence of specific proteases. Emerging strategies rely instead on exogenous triggers such as light and ultrasound to provide spatial and temporal control over antibody activation. These multilayered approaches to targeting diseased tissues are expected to usher in a new generation of precision therapeutics.

Signaling pathways and targeted therapies in lung squamous cell carcinoma: mechanisms and clinical trials

Lung cancer is the leading cause of cancer-related death across the world. Unlike lung adenocarcinoma, patients with lung squamous cell carcinoma (LSCC) have not benefitted from targeted therapies. Although immunotherapy has significantly improved cancer patients' outcomes, the relatively low response rate and severe adverse events hinder the clinical application of this promising treatment in LSCC. Therefore, it is of vital importance to have a better understanding of the mechanisms underlying the pathogenesis of LSCC as well as the inner connection among different signaling pathways, which will surely provide opportunities for more effective therapeutic interventions for LSCC. In this review, new insights were given about classical signaling pathways which have been proved in other cancer types but not in LSCC, including PI3K signaling pathway, VEGF/VEGFR signaling, and CDK4/6 pathway. Other signaling pathways which may have therapeutic potentials in LSCC were also discussed, including the FGFR1 pathway, EGFR pathway, and KEAP1/NRF2 pathway. Next, chromosome 3q, which harbors two key squamous differentiation markers SOX2 and TP63 is discussed as well as its related potential therapeutic targets. We also provided some progress of LSCC in epigenetic therapies and immune checkpoints blockade (ICB) therapies. Subsequently, we outlined some combination strategies of ICB therapies and other targeted therapies. Finally, prospects and challenges were given related to the exploration and application of novel therapeutic strategies for LSCC.

Tumor acidity: From hallmark of cancer to target of treatment

Tumor acidity is one of the cancer hallmarks and is associated with metabolic reprogramming and the use of glycolysis, which results in a high intracellular lactic acid concentration. Cancer cells avoid acid stress major by the activation and expression of proton and lactate transporters and exchangers and have an inverted pH gradient (extracellular and intracellular pHs are acid and alkaline, respectively). The shift in the tumor acid-base balance promotes proliferation, apoptosis avoidance, invasiveness, metastatic potential, aggressiveness, immune evasion, and treatment resistance. For example, weak-base chemotherapeutic agents may have a substantially reduced cellular uptake capacity due to "ion trapping". Lactic acid negatively affects the functions of activated effector T cells, stimulates regulatory T cells, and promotes them to express programmed cell death receptor 1. On the other hand, the inversion of pH gradient could be a cancer weakness that will allow the development of new promising therapies, such as tumor-targeted pH-sensitive antibodies and pH-responsible nanoparticle conjugates with anticancer drugs. The regulation of tumor pH levels by pharmacological inhibition of pH-responsible proteins (monocarboxylate transporters, H+-ATPase, etc.) and lactate dehydrogenase A is also a promising anticancer strategy. Another idea is the oral or parenteral use of buffer systems, such as sodium bicarbonate, to neutralize tumor acidity. Buffering therapy does not counteract standard treatment methods and can be used in combination to increase effectiveness. However, the mechanisms of the anticancer effect of buffering therapy are still unclear, and more research is needed. We have attempted to summarize the basic knowledge about tumor acidity.