Analysis of Circulating Tumor DNA Predicts Outcomes of Short-Course Consolidation Immunotherapy in Unresectable Stage III NSCLC.

INTRODUCTION: The current standard of care for patients with inoperable stage III non-small cell lung cancer includes chemoradiotherapy (CRT) followed by 1 year of checkpoint inhibitor (CPI) therapy. Nevertheless, the optimal duration of consolidation CPI remains unknown. Here, we characterized the relationship between circulating tumor DNA (ctDNA) minimal residual disease (MRD) and clinical outcomes of patients with unresectable locally advanced non-small cell lung cancer treated on a phase 2 trial of short-course consolidation immunotherapy after CRT, with the goal of testing whether ctDNA may be able to identify patients who do not require a full year of treatment. METHODS: Plasma samples for ctDNA analysis were collected from patients on the Big Ten Cancer Research Consortium LUN 16-081 trial after completion of CRT, before day 1 of cycle 2 (C2D1) of CPI (i.e., 1 mo after treatment start), and at the end of up to 6 months of treatment. Tumor-informed ctDNA MRD analysis was performed using cancer personalized profiling by deep sequencing. Levels of ctDNA at each time point were correlated with clinical outcomes. RESULTS: Detection of ctDNA predicted significantly inferior progression-free survival after completion of CRT (24-mo 29% versus 65%, p = 0.0048), before C2D1 of CPI (24-mo 0% versus 72%, p < 0.0001) and at the end of CPI (24-mo 15% versus 67%, p = 0.0011). In addition, patients with decreasing or undetectable ctDNA levels after 1 cycle of CPI had improved outcomes compared with patients with increasing ctDNA levels (24-mo progression-free survival 72% versus 0%, p < 0.0001). Progression of disease occurred within less than 12 months of starting CPI in all patients with increasing ctDNA levels at C2D1. CONCLUSIONS: Detection of ctDNA before, during, or after 6 months of consolidation CPI is strongly associated with inferior outcomes. Our findings suggest that analysis of ctDNA MRD may enable personalizing the duration of consolidation immunotherapy treatment.

Combined JAK inhibition and PD-1 immunotherapy for non-small cell lung cancer patients.

Persistent inflammation driven by cytokines such as type-one interferon (IFN-I) can cause immunosuppression. We show that administration of the Janus kinase 1 (JAK1) inhibitor itacitinib after anti-PD-1 (programmed cell death protein 1) immunotherapy improves immune function and antitumor responses in mice and results in high response rates (67%) in a phase 2 clinical trial for metastatic non-small cell lung cancer. Patients who failed to respond to initial anti-PD-1 immunotherapy but responded after addition of itacitinib had multiple features of poor immune function to anti-PD-1 alone that improved after JAK inhibition. Itacitinib promoted CD8 T cell plasticity and therapeutic responses of exhausted and effector memory-like T cell clonotypes. Patients with persistent inflammation refractory to itacitinib showed progressive CD8 T cell terminal differentiation and progressive disease. Thus, JAK inhibition may improve the efficacy of anti-PD-1 immunotherapy by pivoting T cell differentiation dynamics.

Globally shared TCR repertoires within the tumor-infiltrating lymphocytes of patients with metastatic gynecologic cancer.

Gynecologic cancer, including ovarian cancer and endometrial cancer, is characterized by morphological and molecular heterogeneity. Germline and somatic testing are available for patients to screen for pathogenic variants in genes such as BRCA1/2. Tissue expression levels of immunogenomic markers such as PD-L1 are also being used in clinical research. The basic therapeutic approach to gynecologic cancer combines surgery with chemotherapy. Immunotherapy, while not yet a mainstream treatment for gynecologic cancers, is advancing, with Dostarlimab recently receiving approval as a treatment for endometrial cancer. The goal remains to harness stimulated immune cells in the bloodstream to eradicate multiple metastases, a feat currently deemed challenging in a typical clinical setting. For the discovery of novel immunotherapy-based tumor targets, tumor-infiltrating lymphocytes (TILs) give a key insight on tumor-related immune activities by providing T cell receptor (TCR) sequences. Understanding the TCR repertoires of TILs in metastatic tissues and the circulation is important from an immunotherapy standpoint, as a subset of T cells in the blood have the potential to help kill tumor cells. To explore the relationship between distant tissue biopsy regions and blood circulation, we investigated the TCR beta chain (TCRß) in bulk tumor and matched blood samples from 39 patients with gynecologic cancer. We found that the TCR clones of TILs at different tumor sites were globally shared within patients and had high overlap with the TCR clones in peripheral blood.

Engineered Attenuated Salmonella typhimurium Expressing Neoantigen Has Anticancer Effects.

Neoantigen vaccines are an immunotherapy strategy for treating cancer. The vaccine degrades quickly, so the strategy must include protection and precise targeting for immune cell stimulation. In this study, we engineered attenuated Salmonella typhimurium, which is highly infiltrative to tumors, to act as a carrier for Neoantigen peptide vaccine. Our system used a constitutive promoter vector, so that a single injection of Salmonella expressing Neoantigen could be used without requiring additional induction injections. In vivo experiments on bacteria-treated mice showed that Neoantigen expressed by the engineered carrier infiltrated tumors and resulted in suppressed tumor growth, higher survival rates and longer survival times, a relative increase of CD4 and CD8 T cells, and cytokine release. These results indicate that engineered Salmonella can be used as a carrier for Neoantigen immunotherapy.

Single-cell analysis of a mutant library generated using CRISPR-guided deaminase in human melanoma cells.

CRISPR-based screening methods using single-cell RNA sequencing (scRNA-seq) technology enable comprehensive profiling of gene perturbations from knock-out mutations. However, evaluating substitution mutations using scRNA-seq is currently limited. We combined CRISPR RNA-guided deaminase and scRNA-seq technology to develop a platform for introducing mutations in multiple genes and assessing the mutation-associated signatures. Using this platform, we generated a library consisting of 420 sgRNAs, performed sgRNA tracking analysis, and assessed the effect size of the response to vemurafenib in the human melanoma cell line, which has been well-studied via knockout-based drop-out screens. However, a substitution mutation library screen has not been applied and transcriptional information for mechanisms of action was not assessed. Our platform permits discrimination of several candidate mutations that function differently from other mutations by integrating sgRNA candidates and gene expression readout. We anticipate that our platform will enable high-throughput analyses of the mechanisms related to a variety of biological events.

Multiplex Generation, Tracking, and Functional Screening of Substitution Mutants Using a CRISPR/Retron System.

We developed a clustered regularly interspaced short palindromic repeats (CRISPR)/retron system for multiplexed generation of substitution mutations by coutilization of a retron system that continuously expresses donor DNA and a CRISPR/Cas9 cassette that induces cleavage at target genomic loci. Our system efficiently introduces substitution mutation in the Escherichia coli genome in a high-throughput manner. These substitution mutations can be tracked by analysis of retron plasmid sequences without laborious amplification of individual edited loci. We demonstrated that our CRISPR/retron system can introduce thousands of mutations in a single experiment and be used for screening phenotypes related to chemical responses or fitness changes. We expect that our system could facilitate genome-scale substitution screenings.

Selective targeting of KRAS oncogenic alleles by CRISPR/Cas9 inhibits proliferation of cancer cells.

Mutations within the KRAS oncogene are associated with the proliferation of various cancers. Therapeutic approaches for treating cancers with such mutations have focused on targeting the downstream protein effectors of KRAS. However, to date, no approved treatment has targeted the mutated KRAS oncogene directly. Presently, we used the selectivity of the CRISPR/Cas9 system to directly target mutated KRAS alleles. We designed single-guide RNAs (sgRNAs) to target two specific single-nucleotide missense mutations on KRAS codon-12 located in the seed region adjacent to a protospacer adjacent motif (PAM). Lentiviral transduction of Cas9 and the sgRNAs into cancer cells with respective KRAS mutations resulted in high frequency of indels in the seed region. Indel-associated disruption of the mutant KRAS alleles correlated with reduced viability of the cancer cells. The results indicate that CRISPR-Cas9-mediated genome editing can potentially be used for the treatment of cancer patients, specifically those with oncogenic KRAS mutations.

Straightforward Delivery of Linearized Double-Stranded DNA Encoding sgRNA and Donor DNA for the Generation of Single Nucleotide Variants Based on the CRISPR/Cas9 System.

CRISPR/Cas9 for genome editing requires delivery of a guide RNA sequence and donor DNA for targeted homologous recombination. Typically, single-stranded oligodeoxynucleotide, serving as the donor template, and a plasmid encoding guide RNA are delivered as two separate components. However, in the multiplexed generation of single nucleotide variants, this two-component delivery system is limited by difficulty of delivering a matched pair of sgRNA and donor DNA to the target cell. Here, we describe a novel codelivery system called "sgR-DNA" that uses a linearized double-stranded DNA consisting of donor DNA component and a component encoding sgRNA. Our sgR-DNA-based method is simple to implement because it does not require cloning steps. We also report the potential of our delivery system to generate multiplex genomic substitutions in Escherichia coli and human cells.