Resistance Mechanisms to Anti-PD Cancer Immunotherapy.

The transformative success of antibodies targeting the PD-1 (programmed death 1)/B7-H1 (B7 homolog 1) pathway (anti-PD therapy) has revolutionized cancer treatment. However, only a fraction of patients with solid tumors and some hematopoietic malignancies respond to anti-PD therapy, and the reason for failure in other patients is less known. By dissecting the mechanisms underlying this resistance, current studies reveal that the tumor microenvironment is a major location for resistance to occur. Furthermore, the resistance mechanisms appear to be highly heterogeneous. Here, we discuss recent human cancer data identifying mechanisms of resistance to anti-PD therapy. We review evidence for immune-based resistance mechanisms such as loss of neoantigens, defects in antigen presentation and interferon signaling, immune inhibitory molecules, and exclusion of T cells. We also review the clinical evidence for emerging mechanisms of resistance to anti-PD therapy, such as alterations in metabolism, microbiota, and epigenetics. Finally, we discuss strategies to overcome anti-PD therapy resistance and emphasize the need to develop additional immunotherapies based on the concept of normalization cancer immunotherapy.

The Bis(monoacylglycero)-phosphate Hypothesis: From Lysosomal Function to Therapeutic Avenues.

Lysosomes catabolize and recycle lipids and other biological molecules to maintain cellular homeostasis in diverse nutrient environments. Lysosomal lipid catabolism relies on the stimulatory activity of bis(monoacylglycero)phosphate (BMP), an enigmatic lipid whose levels are altered across myriad lysosome-associated diseases. Here, we review the discovery of BMP over half a century ago and its structural properties that facilitate the activation of lipid hydrolases and recruitment of their coactivators. We further discuss the current, yet incomplete, understanding of BMP catabolism and anabolism. To conclude, we discuss its role in lysosome-associated diseases and the potential for modulating its levels by pharmacologically activating and inhibiting the BMP synthase to therapeutically target lysosomal storage disorders, drug-induced phospholipidosis, Alzheimer's disease, Parkinson's disease, frontotemporal dementia, cancer, and viral infection.

p53: A tale of complexity and context.

The story of p53 is illuminating. Despite widespread attention, the tumor-suppressive functions of wild-type p53 or the oncogenic activities of its cancer-associated mutants are still not fully understood, and our discoveries have not yet led to major therapeutic breakthroughs. There is still much to learn about this fascinating protein.

Challenges and opportunities in oncology drug development and clinical research in China.

As one of the world's most populous countries, China bears a heavy burden and a broad spectrum of cancers, including unique types, providing a unique environment for drug research and development. In recent years, China has leapt forward in oncology drug development and clinical trials, presenting new opportunities and challenges.

Cancer biomarkers: Emerging trends and clinical implications for personalized treatment.

The integration of cancer biomarkers into oncology has revolutionized cancer treatment, yielding remarkable advancements in cancer therapeutics and the prognosis of cancer patients. The development of personalized medicine represents a turning point and a new paradigm in cancer management, as biomarkers enable oncologists to tailor treatments based on the unique molecular profile of each patient's tumor. In this review, we discuss the scientific milestones of cancer biomarkers and explore future possibilities to improve the management of patients with solid tumors. This progress is primarily attributed to the biological characterization of cancers, advancements in testing methodologies, elucidation of the immune microenvironment, and the ability to profile circulating tumor fractions. Integrating these insights promises to continually advance the precision oncology field, fostering better patient outcomes.

DrugMap: A quantitative pan-cancer analysis of cysteine ligandability.

Cysteine-focused chemical proteomic platforms have accelerated the clinical development of covalent inhibitors for a wide range of targets in cancer. However, how different oncogenic contexts influence cysteine targeting remains unknown. To address this question, we have developed "DrugMap," an atlas of cysteine ligandability compiled across 416 cancer cell lines. We unexpectedly find that cysteine ligandability varies across cancer cell lines, and we attribute this to differences in cellular redox states, protein conformational changes, and genetic mutations. Leveraging these findings, we identify actionable cysteines in NF-κB1 and SOX10 and develop corresponding covalent ligands that block the activity of these transcription factors. We demonstrate that the NF-κB1 probe blocks DNA binding, whereas the SOX10 ligand increases SOX10-SOX10 interactions and disrupts melanoma transcriptional signaling. Our findings reveal heterogeneity in cysteine ligandability across cancers, pinpoint cell-intrinsic features driving cysteine targeting, and illustrate the use of covalent probes to disrupt oncogenic transcription-factor activity.

Pan-cancer proteogenomics expands the landscape of therapeutic targets.

Fewer than 200 proteins are targeted by cancer drugs approved by the Food and Drug Administration (FDA). We integrate Clinical Proteomic Tumor Analysis Consortium (CPTAC) proteogenomics data from 1,043 patients across 10 cancer types with additional public datasets to identify potential therapeutic targets. Pan-cancer analysis of 2,863 druggable proteins reveals a wide abundance range and identifies biological factors that affect mRNA-protein correlation. Integration of proteomic data from tumors and genetic screen data from cell lines identifies protein overexpression- or hyperactivation-driven druggable dependencies, enabling accurate predictions of effective drug targets. Proteogenomic identification of synthetic lethality provides a strategy to target tumor suppressor gene loss. Combining proteogenomic analysis and MHC binding prediction prioritizes mutant KRAS peptides as promising public neoantigens. Computational identification of shared tumor-associated antigens followed by experimental confirmation nominates peptides as immunotherapy targets. These analyses, summarized at https://targets.linkedomics.org, form a comprehensive landscape of protein and peptide targets for companion diagnostics, drug repurposing, and therapy development.

Preclinical models for drug discovery for metastatic disease.

Despite many advances, metastatic disease remains essentially uncurable. Thus, there is an urgent need to better understand mechanisms that promote metastasis, drive tumor evolution, and underlie innate and acquired drug resistance. Sophisticated preclinical models that recapitulate the complex tumor ecosystem are key to this process. We begin with syngeneic and patient-derived mouse models that are the backbone of most preclinical studies. Second, we present some unique advantages of fish and fly models. Third, we consider the strengths of 3D culture models for resolving remaining knowledge gaps. Finally, we provide vignettes on multiplexed technologies to advance our understanding of metastatic disease.

Selpercatinib: First approved selective RET inhibitor.

Selpercatinib is a small molecule that binds at the RET kinase active site. It inhibits activity of constitutively dimerized RET fusion proteins and activated point mutants, thereby blocking downstream signals for proliferation and survival. It is the first selective RET inhibitor to be FDA approved for tumor agnostic targeting of oncogenic RET fusion proteins. To view this Bench to Bedside, open or download the PDF.

Immune checkpoint therapy-current perspectives and future directions.

Immune checkpoint therapy (ICT) has dramatically altered clinical outcomes for cancer patients and conferred durable clinical benefits, including cure in a subset of patients. Varying response rates across tumor types and the need for predictive biomarkers to optimize patient selection to maximize efficacy and minimize toxicities prompted efforts to unravel immune and non-immune factors regulating the responses to ICT. This review highlights the biology of anti-tumor immunity underlying response and resistance to ICT, discusses efforts to address the current challenges with ICT, and outlines strategies to guide the development of subsequent clinical trials and combinatorial efforts with ICT.

Determinants of cancer drug pricing and how to overcome the cancer premium.

The high and increasing prices of cancer drugs are a public health challenge. To disrupt the cancer premium and improve patient access to cancer drugs, different action steps are indicated: more transparency on the price determination process and actual prices, value-based pricing, and "price with evidence development."

High-resolution analyses of associations between medications, microbiome, and mortality in cancer patients.

Discerning the effect of pharmacological exposures on intestinal bacterial communities in cancer patients is challenging. Here, we deconvoluted the relationship between drug exposures and changes in microbial composition by developing and applying a new computational method, PARADIGM (parameters associated with dynamics of gut microbiota), to a large set of longitudinal fecal microbiome profiles with detailed medication-administration records from patients undergoing allogeneic hematopoietic cell transplantation. We observed that several non-antibiotic drugs, including laxatives, antiemetics, and opioids, are associated with increased Enterococcus relative abundance and decreased alpha diversity. Shotgun metagenomic sequencing further demonstrated subspecies competition, leading to increased dominant-strain genetic convergence during allo-HCT that is significantly associated with antibiotic exposures. We integrated drug-microbiome associations to predict clinical outcomes in two validation cohorts on the basis of drug exposures alone, suggesting that this approach can generate biologically and clinically relevant insights into how pharmacological exposures can perturb or preserve microbiota composition. The application of a computational method called PARADIGM to a large dataset of cancer patients' longitudinal fecal specimens and detailed daily medication records reveals associations between drug exposures and the intestinal microbiota that recapitulate in vitro findings and are also predictive of clinical outcomes.

Designing antibodies as therapeutics.

Antibody therapeutics are a large and rapidly expanding drug class providing major health benefits. We provide a snapshot of current antibody therapeutics including their formats, common targets, therapeutic areas, and routes of administration. Our focus is on selected emerging directions in antibody design where progress may provide a broad benefit. These topics include enhancing antibodies for cancer, antibody delivery to organs such as the brain, gastrointestinal tract, and lungs, plus antibody developability challenges including immunogenicity risk assessment and mitigation and subcutaneous delivery. Machine learning has the potential, albeit as yet largely unrealized, for a transformative future impact on antibody discovery and engineering.

Sublethal cytochrome c release generates drug-tolerant persister cells.

Drug-tolerant persister cells (persisters) evade apoptosis upon targeted and conventional cancer therapies and represent a major non-genetic barrier to effective cancer treatment. Here, we show that cells that survive treatment with pro-apoptotic BH3 mimetics display a persister phenotype that includes colonization and metastasis in vivo and increased sensitivity toward ferroptosis by GPX4 inhibition. We found that sublethal mitochondrial outer membrane permeabilization (MOMP) and holocytochrome c release are key requirements for the generation of the persister phenotype. The generation of persisters is independent of apoptosome formation and caspase activation, but instead, cytosolic cytochrome c induces the activation of heme-regulated inhibitor (HRI) kinase and engagement of the integrated stress response (ISR) with the consequent synthesis of ATF4, all of which are required for the persister phenotype. Our results reveal that sublethal cytochrome c release couples sublethal MOMP to caspase-independent initiation of an ATF4-dependent, drug-tolerant persister phenotype.

Enhanced safety and efficacy of protease-regulated CAR-T cell receptors.

Regulatable CAR platforms could circumvent toxicities associated with CAR-T therapy, but existing systems have shortcomings including leakiness and attenuated activity. Here, we present SNIP CARs, a protease-based platform for regulating CAR activity using an FDA-approved small molecule. Design iterations yielded CAR-T cells that manifest full functional capacity with drug and no leaky activity in the absence of drug. In numerous models, SNIP CAR-T cells were more potent than constitutive CAR-T cells and showed diminished T cell exhaustion and greater stemness. In a ROR1-based CAR lethality model, drug cessation following toxicity onset reversed toxicity, thereby credentialing the platform as a safety switch. In the same model, reduced drug dosing opened a therapeutic window that resulted in tumor eradication in the absence of toxicity. SNIP CARs enable remote tuning of CAR activity, which provides solutions to safety and efficacy barriers that are currently limiting progress in using CAR-T cells to treat solid tumors.

The interaction between signal regulatory protein alpha (SIRPα) and CD47: structure, function, and therapeutic target.

CD47 is a broadly expressed membrane protein that interacts with the myeloid inhibitory immunoreceptor SIRPα (also termed CD172a or SHPS-1). SIRPα is the prototypic member of the SIRP paired receptor family of closely related SIRP proteins. Engagement of SIRPα by CD47 provides a downregulatory signal that inhibits host cell phagocytosis, and CD47 therefore functions as a "don't-eat-me" signal. Here, we discuss recent structural analysis of CD47-SIRPα interactions and implications of this for the function and evolution of SIRPα and paired receptors in general. Furthermore, we review the proposed roles of CD47-SIRPα interactions in phagocytosis, (auto)immunity, and host defense, as well as its potential significance as a therapeutic target in cancer and inflammation and for improving graft survival in xenotransplantation.

Dinner is served, sir: Fighting cancer with the right diet.

Altered metabolism of tumors offers an opportunity to use metabolic interventions as a therapeutic strategy. Lien et al. demonstrate that understanding how specific diets with different carbohydrate and fat composition affect tumor metabolism is essential in order to use this opportunity efficiently.

Strength in numbers: predicting response to checkpoint inhibitors from large clinical datasets.

The advent of immune checkpoint blockers for cancer therapy has spawned great interest in identifying molecular features reflecting the complexity of tumor immunity, which can subsequently be leveraged as predictive biomarkers. In a thorough big-data approach analyzing the largest series of homogenized molecular and clinical datasets, Litchfield et al. identified a set of genomic biomarkers that identifies immunotherapy responders across cancer types.

Connecting communities to tackle cancer from many sides.

Interdisciplinary work has played a key role in Dr. Elizabeth Eisenhauer's wide-ranging research contributions and leadership in cancer clinical trials, drug delivery, treatment standards, and research and prevention strategy. Cell editor Emma Yee talked with Dr. Eisenhauer, recipient of the 2021 Canada Gairdner Wightman Award, to learn more about the factors that influenced her work in cancer care and the lessons she learned along the way. This conversation is presented below, edited for clarity and length. Note the National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) was renamed the Canadian Cancer Trials Group (CCTG) in 2016. In this interview, the two are used interchangeably.

Hallmarks of response, resistance, and toxicity to immune checkpoint blockade.

Unprecedented advances have been made in cancer treatment with the use of immune checkpoint blockade (ICB). However, responses are limited to a subset of patients, and immune-related adverse events (irAEs) can be problematic, requiring treatment discontinuation. Iterative insights into factors intrinsic and extrinsic to the host that impact ICB response and toxicity are critically needed. Our understanding of the impact of host-intrinsic factors (such as the host genome, epigenome, and immunity) has evolved substantially over the past decade, with greater insights on these factors and on tumor and immune co-evolution. Additionally, we are beginning to understand the impact of acute and cumulative exposures-both internal and external to the host (i.e., the exposome)-on host physiology and response to treatment. Together these represent the current day hallmarks of response, resistance, and toxicity to ICB. Opportunities built on these hallmarks are duly warranted.