KRAS G12V neoantigen specific T cell receptor for adoptive T cell therapy against tumors

Cold and hot tumors: from molecular mechanisms to targeted therapy

Immunotherapy has made significant strides in cancer treatment, particularly through immune checkpoint blockade (ICB), which has shown notable clinical benefits across various tumor types. Despite the transformative impact of ICB treatment in cancer therapy, only a minority of patients exhibit a positive response to it. In patients with solid tumors, those who respond well to ICB treatment typically demonstrate an active immune profile referred to as the "hot" (immune-inflamed) phenotype. On the other hand, non-responsive patients may exhibit a distinct "cold" (immune-desert) phenotype, differing from the features of "hot" tumors. Additionally, there is a more nuanced "excluded" immune phenotype, positioned between the "cold" and "hot" categories, known as the immune "excluded" type. Effective differentiation between "cold" and "hot" tumors, and understanding tumor intrinsic factors, immune characteristics, TME, and external factors are critical for predicting tumor response and treatment results. It is widely accepted that ICB therapy exerts a more profound effect on "hot" tumors, with limited efficacy against "cold" or "altered" tumors, necessitating combinations with other therapeutic modalities to enhance immune cell infiltration into tumor tissue and convert "cold" or "altered" tumors into "hot" ones. Therefore, aligning with the traits of "cold" and "hot" tumors, this review systematically delineates the respective immune characteristics, influencing factors, and extensively discusses varied treatment approaches and drug targets based on "cold" and "hot" tumors to assess clinical efficacy.

Overcoming immune evasion from post-translational modification of a mutant KRAS epitope to achieve TCR-T cell-mediated antitumor activity

T cell receptor (TCR)-T cell immunotherapy, in which T cells are engineered to express a TCR targeting a tumor epitope, is a form of adoptive cell therapy (ACT) that has exhibited promise against various tumor types. Mutants of oncoprotein KRAS, particularly at glycine-12 (G12), are frequent drivers of tumorigenicity, making them attractive targets for TCR-T cell therapy. However, class I-restricted TCRs specifically targeting G12-mutant KRAS epitopes in the context of tumors expressing HLA-A2, the most common human HLA-A allele, have remained elusive despite evidence an epitope encompassing such mutations can bind HLA-A2 and induce T cell responses. We report post-translational modifications (PTMs) on this epitope may allow tumor cells to evade immunologic pressure from TCR-T cells. A lysine side chain-methylated KRAS G12V peptide, rather than the unmodified epitope, may be presented in HLA-A2 by tumor cells and impact TCR recognition. Using a novel computationally guided approach, we developed by mutagenesis TCRs that recognize this methylated peptide, enhancing tumor recognition and destruction. Additionally, we identified TCRs with similar functional activity in normal repertoires from primary T cells by stimulation with modified peptide, clonal expansion, and selection. Mechanistically, a gene knockout screen to identify mechanism(s) by which tumor cells methylate/demethylate this epitope unveiled SPT6 as a demethylating protein that could be targeted to improve effectiveness of these new TCRs. Our findings highlight the role of PTMs in immune evasion and suggest identifying and targeting such modifications should make effective ACTs available for a substantially greater range of tumors than the current therapeutic landscape.

One-sentence summary

Tumor cell methylation of KRAS G12V epitope in HLA-A2 permits immune evasion, and new TCRs were generated to overcome this with engineered cell therapy.

Clinical advances and challenges associated with TCR-T cell therapy for cancer treatment

Background

T cell receptor (TCR)-T cell therapy is an innovative form of cancer immunotherapy that genetically modifies patients' T cells to target and destroy cancer cells. However, the current status of clinical trials of TCR-T cell therapy for the treatment of cancer remains unclear. This study aimed to comprehensively analyze the registration trials related to TCR-T cell therapy for the treatment of cancer.

Methods

A comprehensive search was conducted in the Trialtrove database for all clinical trials related to TCR-T cell therapy registered by August 1, 2024. Inclusion criteria focused on trials targeting TCR-T cell therapy for oncology, and excluded observational studies and incomplete data. Statistical analysis was performed on key trial characteristics, with between-group comparisons utilizing chi-square or Fisher's exact tests.

Results

Analysis of 174 eligible clinical trials revealed that TCR-T cell therapy exhibits significant efficacy across various tumor types, particularly in refractory hematologic malignancies and certain solid tumors. Additionally, combining TCR-T cell therapy with other immunotherapies enhanced these anti-tumor effects.

Conclusion

TCR-T cell therapy holds substantial promise for cancer treatment. Future research should focus on optimizing treatment protocols, enhancing efficacy, and minimizing prices to fully realize the potential of this therapy.

Ready, Set, Go: Setting Off on the Mission to Target KRAS in Colorectal Cancer

Understanding the landscape of KRAS mutations in #CRC is crucial with over 2.8M annual diagnoses worldwide. Explore promising therapies and ongoing challenges in this comprehensive review. #CancerResearch #KRAS #ColorectalCancer.

Unveiling the role of KRAS in Chinese colorectal cancer patients: a positive influence on tumor mutational burden

Background

One of the main challenges associated with the development of therapeutic and diagnostic strategies for patients with colorectal cancer (CRC) is the establishment of minimally invasive and efficient biomarkers. Pertinent genes in CRC have been identified through their functions in systematic mutagenesis screens. KRAS is considered a dominant mutated oncogene that contributes to pathogenesis of CRC. This study aimed to explore the genomic alternations of KRAS in a CRC population.

Methods

Sequencing data of 94 Chinese patients with CRC were prospectively collected and analyzed using next-generation sequencing (NGS). The influence of KRAS and its associated subtype co-mutations on the expression level of the tumor mutational burden (TMB) was investigated. The objective of our study was to assess the potential prognostic significance of KRAS and other driving oncogenes in determining the clinical efficacy of immunotherapy.

Results

The gene mutation rates of TP53, APC, and KRAS were 81.91%, 71.28%, and 43.62%, respectively. Additionally, KRAS G12D displayed a relatively higher mutation rate than other KRAS-mutant subtypes. Increased TMB was observed in cases of KRAS and BRAF mutation combined with APC single mutation; furthermore, the expression of TMB in G12V was the highest, and G12D presented the lowest TMB in single KRAS-mutant subtypes or the combination with APC mutations.

Conclusions

The TMB driven by KRAS co-mutations may have the potential to be used as a key biomarker for prediction of treatment outcomes of immune checkpoint inhibitors (ICIs) in patients with CRC, especially with APC co-mutation.

Enhancing cancer immunotherapy: Nanotechnology-mediated immunotherapy overcoming immunosuppression

Immunotherapy is an important cancer treatment method that offers hope for curing cancer patients. While immunotherapy has achieved initial success, a major obstacle to its widespread adoption is the inability to benefit the majority of patients. The success or failure of immunotherapy is closely linked to the tumor's immune microenvironment. Recently, there has been significant attention on strategies to regulate the tumor immune microenvironment in order to stimulate anti-tumor immune responses in cancer immunotherapy. The distinctive physical properties and design flexibility of nanomedicines have been extensively utilized to target immune cells (including tumor-associated macrophages (TAMs), T cells, myeloid-derived suppressor cells (MDSCs), and tumor-associated fibroblasts (TAFs)), offering promising advancements in cancer immunotherapy. In this article, we have reviewed treatment strategies aimed at targeting various immune cells to regulate the tumor immune microenvironment. The focus is on cancer immunotherapy models that are based on nanomedicines, with the goal of inducing or enhancing anti-tumor immune responses to improve immunotherapy. It is worth noting that combining cancer immunotherapy with other treatments, such as chemotherapy, radiotherapy, and photodynamic therapy, can maximize the therapeutic effects. Finally, we have identified the challenges that nanotechnology-mediated immunotherapy needs to overcome in order to design more effective nanosystems.

Exploring Predictive and Prognostic Biomarkers in Colorectal Cancer: A Comprehensive Review

Colorectal cancer (CRC) remains the second leading cause of cancer-related mortality worldwide. While immune checkpoint inhibitors have significantly improved patient outcomes, their effectiveness is mostly limited to tumors with microsatellite instability (MSI-H/dMMR) or an increased tumor mutational burden, which comprise 10% of cases. Advancing personalized medicine in CRC hinges on identifying predictive biomarkers to guide treatment decisions. This comprehensive review examines established tissue markers such as KRAS and HER2, highlighting their roles in resistance to anti-EGFR agents and discussing advances in targeted therapies for these markers. Additionally, this review summarizes encouraging data on promising therapeutic targets and highlights the clinical utility of liquid biopsies. By synthesizing current evidence and identifying knowledge gaps, this review provides clinicians and researchers with a contemporary understanding of the biomarker landscape in CRC. Finally, the review examines future directions and challenges in translating promising biomarkers into clinical practice, with the goal of enhancing personalized medicine approaches for colorectal cancer patients.

Identification and structural characterization of a mutant KRAS-G12V specific TCR restricted by HLA-A3

Mutations in KRAS are some of the most common across multiple cancer types and are thus attractive targets for therapy. Recent studies demonstrated that mutant KRAS generates immunogenic neoantigens that are targetable by adoptive T-cell therapy in metastatic diseases. To expand mutant KRAS-specific immunotherapies, it is critical to identify additional HLA-I allotypes that can present KRAS neoantigens and their cognate T-cell receptors (TCR). Here, we identified a murine TCR specific to a KRAS-G12V neoantigen (7VVVGAVGVGK16) using a vaccination approach with transgenic mice expressing HLA-A*03:01 (HLA-A3). This TCR demonstrated exquisite specificity for mutant G12V and not WT KRAS peptides. To investigate the molecular basis for neoantigen recognition by this TCR, we determined its structure in complex with HLA-A3(G12V). G12V-TCR CDR3β and CDR1β formed a hydrophobic pocket to interact with p6 Val of the G12V but not the WT KRAS peptide. To improve the tumor sensitivity of this TCR, we designed rational substitutions to improve TCR:HLA-A3 contacts. Two substitutions exhibited modest improvements in TCR binding avidity to HLA-A3 (G12V) but did not sufficiently improve T-cell sensitivity for further clinical development. Our study provides mechanistic insight into how TCRs detect neoantigens and reveals the challenges in targeting KRAS-G12V mutations.

The next-generation KRAS inhibitors…What comes after sotorasib and adagrasib?

The Kirsten rat sarcoma viral oncogene homolog (KRAS) is one of the first driver oncogenes identified in human cancer in the early 1980s. However, it has been deemed 'undruggable' for nearly four decades until the discovery of KRAS G12C covalent inhibitors, which marked a pivotal breakthrough. Currently, sotorasib and adagrasib have been approved by the US FDA to treat patients with non-small cell lung cancer (NSCLC) harboring KRAS G12C mutation. However, their efficacy is somewhat limited compared to that of other targeted therapies owing to intrinsic resistance or early acquisition of resistance. While G12C is the predominant subtype of KRAS mutations in NSCLC, G12D/V is prevalent in colorectal and pancreatic cancers. These facts have spurred active research to develop more potent KRAS G12C inhibitors as well as inhibitors targeting non-G12C KRAS mutations. Novel approaches, such as molecular shielding or targeted protein degradation, are also under development. Combining KRAS inhibitors with inhibitors of the receptor-tyrosine kinase-RAS-mitogen-activated protein kinase (MAPK) pathway is underway to counteract redundant feedback mechanisms. Additionally, immunological approaches utilizing T-cell receptor (TCR)-engineered T cell therapy or vaccines, and Hapimmune antibodies are ongoing. This review delineates the recent advancements in KRAS inhibitor development in the post-sotorasib/adagrasib era, with a focus on NSCLC.

Identification of HPV-E7 specific TCRs for tumor immunotherapy

The oncogenic protein E7 of the Human Papillomavirus (HPV) is constitutionally expressed in HPV-associated tumors and has the potential to be targeted in T cell receptor (TCR)-based immunotherapy. Adoptive transfer of TCR-engineered T (TCR-T) cells has shown promise as a therapeutic approach for HPV-induced tumors. This study aimed to identify HPV-E7 specific TCRs from HLA-A11:01 transgenic mice through single-cell sorting and sequencing facilitated by E789-97/HLA-A11:01 tetramer. Two dominant TCRs were identified, which exhibited specific binding to E789-97 presented in the context of HLA-A*11:01. TCR-T cells were prepared by infecting primary T cells with lentiviruses containing the TCR genes, and the two TCRs demonstrated substantial responsiveness and showed CD8+ dependent cytokine secretion characteristics. Further analyses of the cytokine profiles revealed that the two TCRs were capable of exerting polyfunctional responses upon specific stimulation. These findings suggest that the two TCRs represent promising candidates for the development of future therapeutic drugs targeting HPV-E7 in the context of HLA-A*11:01 for tumor immunotherapy.

The recent advancement of TCR-T cell therapies for cancer treatment

Adoptive cell therapies involve infusing engineered immune cells into cancer patients to recognize and eliminate tumor cells. Adoptive cell therapy, as a form of living drug, has undergone explosive growth over the past decade. The recognition of tumor antigens by the T-cell receptor (TCR) is one of the natural mechanisms that the immune system used to eliminate tumor cells. TCR-T cell therapy, which involves introducing exogenous TCRs into patients' T cells, is a novel cell therapy strategy. TCR-T cell therapy can target the entire proteome of cancer cells. Engineering T cells with exogenous TCRs to help patients combat cancer has achieved success in clinical trials, particularly in treating solid tumors. In this review, we examine the progress of TCR-T cell therapy over the past five years. This includes the discovery of new tumor antigens, protein engineering techniques for TCR, reprogramming strategies for TCR-T cell therapy, clinical studies on TCR-T cell therapy, and the advancement of TCR-T cell therapy in China. We also propose several potential directions for the future development of TCR-T cell therapy.

Targeting RAF dimers in RAS mutant tumors: From biology to clinic

RAS mutations occur in approximately 30% of tumors worldwide and have a poor prognosis due to limited therapies. Covalent targeting of KRAS G12C has achieved significant success in recent years, but there is still a lack of efficient therapeutic approaches for tumors with non-G12C KRAS mutations. A highly promising approach is to target the MAPK pathway downstream of RAS, with a particular focus on RAF kinases. First-generation RAF inhibitors have been authorized to treat BRAF mutant tumors for over a decade. However, their use in RAS-mutated tumors is not recommended due to the paradoxical ERK activation mainly caused by RAF dimerization. To address the issue of RAF dimerization, type II RAF inhibitors have emerged as leading candidates. Recent clinical studies have shown the initial effectiveness of these agents against RAS mutant tumors. Promisingly, type II RAF inhibitors in combination with MEK or ERK inhibitors have demonstrated impressive efficacy in RAS mutant tumors. This review aims to clarify the importance of RAF dimerization in cellular signaling and resistance to treatment in tumors with RAS mutations, as well as recent progress in therapeutic approaches to address the problem of RAF dimerization in RAS mutant tumors.

Identification and affinity enhancement of T-cell receptor targeting a KRASG12V cancer neoantigen

Neoantigens derived from somatic mutations in Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS), the most frequently mutated oncogene, represent promising targets for cancer immunotherapy. Recent research highlights the potential role of human leukocyte antigen (HLA) allele A*11:01 in presenting these altered KRAS variants to the immune system. In this study, we successfully generate and identify murine T-cell receptors (TCRs) that specifically recognize KRAS8-16G12V from three predicted high affinity peptides. By determining the structure of the tumor-specific 4TCR2 bound to KRASG12V-HLA-A*11:01, we conduct structure-based design to create and evaluate TCR variants with markedly enhanced affinity, up to 15.8-fold. This high-affinity TCR mutant, which involved only two amino acid substitutions, display minimal conformational alterations while maintaining a high degree of specificity for the KRASG12V peptide. Our research unveils the molecular mechanisms governing TCR recognition towards KRASG12V neoantigen and yields a range of affinity-enhanced TCR mutants with significant potential for immunotherapy strategies targeting tumors harboring the KRASG12V mutation.

Structural basis for self-discrimination by neoantigen-specific TCRs

T cell receptors (TCR) are pivotal in mediating tumour cell cytolysis via recognition of mutation-derived tumour neoantigens (neoAgs) presented by major histocompatibility class-I (MHC-I). Understanding the factors governing the emergence of neoAg from somatic mutations is a major focus of current research. However, the structural and cellular determinants controlling TCR recognition of neoAgs remain poorly understood. This study describes the multi-level analysis of a model neoAg from the B16F10 murine melanoma, H2-Db/Hsf2 p.K72N68-76, as well as its cognate TCR 47BE7. Through cellular, molecular and structural studies we demonstrate that the p.K72N mutation enhances H2-Db binding, thereby improving cell surface presentation and stabilizing the TCR 47BE7 epitope. Furthermore, TCR 47BE7 exhibited high functional avidity and selectivity, attributable to a broad, stringent, binding interface enabling recognition of native B16F10 despite low antigen density. Our findings provide insight into the generation of anchor-residue modified neoAg, and emphasize the value of molecular and structural investigations of neoAg in diverse MHC-I contexts for advancing the understanding of neoAg immunogenicity.

Tertiary lymphoid structures in cancer: immune mechanisms and clinical implications

Cancer is a major cause of death globally, and traditional treatments often have limited efficacy and adverse effects. Immunotherapy has shown promise in various malignancies but is less effective in tumors with low immunogenicity or immunosuppressive microenvironment, especially sarcomas. Tertiary lymphoid structures (TLSs) have been associated with a favorable response to immunotherapy and improved survival in cancer patients. However, the immunological mechanisms and clinical significance of TLS in malignant tumors are not fully understood. In this review, we elucidate the composition, neogenesis, and immune characteristics of TLS in tumors, as well as the inflammatory response in cancer development. An in-depth discussion of the unique immune characteristics of TLSs in lung cancer, breast cancer, melanoma, and soft tissue sarcomas will be presented. Additionally, the therapeutic implications of TLS, including its role as a marker of therapeutic response and prognosis, and strategies to promote TLS formation and maturation will be explored. Overall, we aim to provide a comprehensive understanding of the role of TLS in the tumor immune microenvironment and suggest potential interventions for cancer treatment.

Conformational plasticity of RAS Q61 family of neoepitopes results in distinct features for targeted recognition

The conformational landscapes of peptide/human leucocyte antigen (pHLA) protein complexes encompassing tumor neoantigens provide a rationale for target selection towards autologous T cell, vaccine, and antibody-based therapeutic modalities. Here, using complementary biophysical and computational methods, we characterize recurrent RAS55-64 Q61 neoepitopes presented by the common HLA-A*01:01 allotype. We integrate sparse NMR restraints with Rosetta docking to determine the solution structure of NRASQ61K/HLA-A*01:01, which enables modeling of other common RAS55-64 neoepitopes. Hydrogen/deuterium exchange mass spectrometry experiments alongside molecular dynamics simulations reveal differences in solvent accessibility and conformational plasticity across a panel of common Q61 neoepitopes that are relevant for recognition by immunoreceptors. Finally, we predict binding and provide structural models of NRASQ61K antigens spanning the entire HLA allelic landscape, together with in vitro validation for HLA-A*01:191, HLA-B*15:01, and HLA-C*08:02. Our work provides a basis to delineate the solution surface features and immunogenicity of clinically relevant neoepitope/HLA targets for cancer therapy.

Structural basis for T cell recognition of cancer neoantigens and implications for predicting neoepitope immunogenicity

Adoptive cell therapy (ACT) with tumor-specific T cells has been shown to mediate durable cancer regression. Tumor-specific T cells are also the basis of other therapies, notably cancer vaccines. The main target of tumor-specific T cells are neoantigens resulting from mutations in self-antigens over the course of malignant transformation. The detection of neoantigens presents a major challenge to T cells because of their high structural similarity to self-antigens, and the need to avoid autoimmunity. How different a neoantigen must be from its wild-type parent for it to induce a T cell response is poorly understood. Here we review recent structural and biophysical studies of T cell receptor (TCR) recognition of shared cancer neoantigens derived from oncogenes, including p53R175H, KRASG12D, KRASG12V, HHATp8F, and PIK3CAH1047L. These studies have revealed that, in some cases, the oncogenic mutation improves antigen presentation by strengthening peptide-MHC binding. In other cases, the mutation is detected by direct interactions with TCR, or by energetically driven or other indirect strategies not requiring direct TCR contacts with the mutation. We also review antibodies designed to recognize peptide-MHC on cell surfaces (TCR-mimic antibodies) as an alternative to TCRs for targeting cancer neoantigens. Finally, we review recent computational advances in this area, including efforts to predict neoepitope immunogenicity and how these efforts may be advanced by structural information on peptide-MHC binding and peptide-MHC recognition by TCRs.