Cancer Cell

The addition of aPD1 to 5-FU/platinum in advanced gastric cancer (GC) yields variable responses. To understand cooperativity between chemotherapy and immunotherapy, we previously reported a phase II trial sequentially adding pembrolizumab to 5-FU/platinum. In this study, we use single-cell RNA- and TCR-sequencing to analyze 66,813 T cells from primary tumor biopsies pre-treatment, post-chemotherapy, and post-immunotherapy in 33 patients. We observed greater abundance, persistence, and recruitment of T cells with predicted tumor-reactivity in patients with prolonged progression-free survival (slow progressors). Increased B cell abundance and predicted B cell to T cell interactions supported T cell memory and co-stimulation, providing a mechanism for increased abundance and persistence of progenitor-exhausted and tumor-reactive T cells in slow progressors. T cell clones emerging in the tumor after immunotherapy were in the blood before treatment only in slow progressors. Our study thus highlights pre-treatment and early chemotherapy-induced T cell dynamics and B cell to T cell interactions that may drive durable response to chemoimmunotherapy in GC.

There is a pressing need to characterise the nature, extent and duration of immune response to SARS-CoV-2 in cancer patients and inform risk-reduction strategies and preserve cancer outcomes. CAPTURE is a prospective, longitudinal cohort study of cancer patients and healthcare workers (HCWs) integrating longitudinal immune profiling and clinical annotation. We evaluated 529 blood samples and 1051 oronasopharyngeal swabs from 144 cancer patients and 73 HCWs and correlated with >200 clinical variables. In patients with solid cancers and HCWs, S1-reactive and neutralising antibodies to SARS-CoV-2 were detectable five months post-infection. SARS-CoV-2-specific T-cell responses were detected, and CD4+ T-cell responses correlated with S1 antibody levels. Patients with haematological malignancies had impaired but partially compensated immune responses. Overall, cancer stage, disease status, and therapies did not correlate with immune responses. These findings have implications for understanding individual risks and potential effectiveness of SARS-CoV-2 vaccination in the cancer population.

Chimeric antigen receptor (CAR)-modified V{delta}2 T cells are an attractive therapeutic cell platform for cancer immunotherapy. However, their clinical efficacy is limited by short in vivo persistence due to insufficient cytokine support and high susceptibility to activation-induced cell death (AICD). Through comparison of membrane-bound (mb) cytokines, we identified mbIL-18 to support superior anti-tumor activity of CAR-V{delta}2 T cells in vitro and in vivo. To reduce constitutive surface exposure of IL-18 and enable antigen-driven signal 3, we fused MyD88 - the key IL-18R signaling mediator - to an extracellular domain of Fas (Fas88). Antigen stimulation-induced FasL engagement of Fas88 triggered IL-18 signaling while simultaneously protecting V{delta}2 T cells from AICD. Fas88-armed human CAR-V{delta}2 T cells produced superior yet stimulation-dependent in vivo expansion and functional persistence in xenograft models of hematologic and solid malignancies. Together, these findings highlight the importance of IL-18 signaling and AICD resistance for CAR-V{delta}2 T cell activity, enabling a single-transgene modification to limit inflammatory risk and facilitate clinical translation.

Non-small cell lung cancer (NSCLC) patients exhibit heterogeneous responses to immunotherapy (IT) with high resistance rates, highlighting the need for precise biomarkers predictive of treatment outcomes. In a prospective cohort study, we longitudinally assessed liquid biopsy samples from NSCLC patients undergoing IT at four distinct time points (T1 pre-treatment, T2 post-second cycle, T3 six months, and T4 one year). We profiled plasma-derived cell-free DNA methylation and extracellular vesicle-associated microRNAs from 79 metastatic NSCLC patients treated with immune checkpoint inhibitors (ICIs). High-dimensional omics data were integrated using Multi-Omics Factor Analysis (MOFA2) to uncover latent molecular subtypes, which we termed MOFA-Derived Clusters (MDCs), independently established at baseline (MDC-T1) and post-second cycle (MDC-T2). Differential expression and methylation analyses, pathway enrichment, and immune phenotyping via flow cytometry were used to characterize the molecular and immunological landscape of each MDC. External validation was performed using independent NSCLC cohorts for miRNAs (Genova et al., 2024, n=54) and methylation (SMC-Cohort, GSE119144, n=57). MDCs captured divergent survival outcomes and reflected biologically coherent processes including angiogenesis, cytoskeletal remodeling, and immune signaling. Projection of MDCs onto later time points (T3, T4) supported the temporal relevance of early molecular signatures. MDCs also displayed immunological correlates via circulating immune cell subsets. Importantly, MDC classifiers demonstrated consistent survival stratification in external cohorts, particularly MDC-T2. This study defines a multi-omic, liquid biopsy-based framework for molecular subtyping in NSCLC to manage ICI treatment. Our MDC signatures reveal clinically meaningful, treatment-informative biology and offer a path toward minimally invasive patient stratification in immuno-oncology.

GD2-CAR T cell therapy has demonstrated clinical benefit in patients with H3K27M+ diffuse midline glioma (DMG), but the durability of response has been limited in many patients1,2. To identify mechanisms of therapeutic resistance, we conducted longitudinal single-cell RNA and TCR sequencing of cerebrospinal fluid (CSF) lymphocytes from DMG patients receiving intravenous followed by sequential intracerebral GD2-CAR therapy, with lymphodepleting chemotherapy administered once prior to the start of CAR T cell therapy (NCT04196413). CSF GD2-CAR T cells manifested limited persistence and clonal expansion, while non-engineered CSF lymphocytes underwent significant clonal expansion and repertoire stabilization, ultimately dominating the CSF immune compartment. Concurrently, peripheral blood CD4+ and CD8+ T cells manifested anti-CAR immune reactivity targeting epitopes enriched within murine-derived and engineered junctional regions of the CAR construct. This was associated with appearance of circulating Human Anti-CAR Antibodies (HACAs) that bound cells expressing the GD2-CAR, as well as clonal expansion of CSF B cells which produced HACA which impeded the cytotoxic activity of GD2-CAR T cells. In several cases, appearance of circulating HACA temporally correlated with disease progression and across the patient population, and levels of circulating HACA inversely correlated with circulating CAR T cell persistence. These findings reveal robust induction of systemic and CNS adaptive T cell and B cell responses to GD2-CAR T cells following intravenous then sequential intracerebroventricular GD2-CAR therapy and provide strong evidence that anti-CAR immunity is a significant contributor to therapeutic resistance in this setting.

Adoptive cell therapy (ACT) in solid tumors is limited by tumor microenvironment (TME)-imposed resistance mechanisms that are inadequately addressed by conventional systems. We developed tissue-preserving patient-derived explants (PDEs) from lung and ovarian cancer to interrogate redirected T cell immunity in intact human tissue. Using mesothelin-targeting bispecific T cell engager (BiTE(R), Amgen trademark)-secreting T cells, we observed antigen-dependent but heterogeneous responses across lesions. An integrated ex vivo response score stratified responder and non-responder TMEs, revealing that resistance associates with reduced antigen density, stromal dominance, and limited myeloid licensing rather than baseline lymphocyte abundance. Elevated prostaglandin E2 (PGE2) inversely correlated with BiTE-induced T cell activation, identifying the COX/PGE2 axis as a tissue-imposed constraint. COX inhibition amplified interferon-driven immune programs enhanced intratumoral CD8 infiltration, and increased tumor-restricted apoptosis. Spatial transcriptomics localized these effects to tumor-proximal immune hubs in responders, whereas non-responders remained stromally insulated. These findings position PDEs as human-based new approach methodologies enabling combinatorial ACT pharmacodynamics and stratification. Statement of significancePatient-derived explants provide a human-based new approach methodology to interrogate adoptive immunotherapy pharmacodynamics within intact tumor microenvironments in NSCLC and HGSOC. We uncover a COX/PGE2-mediated tissue ceiling that limits BiTE-driven T cell function and demonstrate that COX inhibition reactivates tumor-proximal immune hubs to enhance intratumoral CD8 infiltration and tumor-restricted apoptosis, informing patient stratification and rational combinations.

Glioblastoma heterogeneity and plasticity remain controversial, with proposed subtypes representing the average of highly heterogeneous admixtures of independent transcriptional states. Single-cell, protein-activity-based analysis allowed full quantification of >6,000 regulatory and signaling proteins, thus providing a previously unattainable single-cell characterization level. This helped identify four novel, molecularly distinct subtypes that successfully harmonize across multiple GBM datasets, including previously published bulk and single-cell profiles and single cell profiles from seven orthotopic PDX models, representative of prior subtype diversity. GBM is thus characterized by the plastic coexistence of single cells in two mutually-exclusive developmental lineages, with additional stratification provided by their proliferative potential. Consistently, all previous subtypes could be recapitulated by single-cell mixtures drawn from newly identified states. Critically, drug sensitivity was predicted and validated as highly state-dependent, both in single-cell assays from patient-derived explants and in PDX models, suggesting that successful treatment requires combinations of multiple drugs targeting these distinct tumor states.\n\nSignificanceWe propose a new, 4-subtype GBM classification, which harmonizes across bulk and single-cell datasets. Single-cell mixtures from these subtypes effectively recapitulate all prior classifications, suggesting that the latter are a byproduct of GBM heterogeneity. Finally, we predict single-cell level activity of three clinically-relevant drugs, and validate them in patient-derived explant.

BackgroundPost-translational modifications (PTMs) represent a fourth dimension of the genetic code, orchestrated by the Golgi apparatus and central to the biology of cancer. The prevailing paradigm of oncofetal reprogramming posits that cancer cells reactivate embryonic developmental programs to drive tumorigenesis; however, the lineage-specific nature of this reversion remains incompletely defined. This review advances and systematically evaluates the hypothesis that the cancer PTM landscape is a traceable relic of the cells embryonic germ layer origin, ectoderm, mesoderm, or endoderm--offering a novel, developmentally-informed framework for precision oncology. ObjectivesTo systematically review and synthesize the global evidence linking cancer PTMs to their developmental origins and to evaluate the efficacy, safety, and implementation of PTM-targeted therapeutics through this novel developmental lens, with LLM assistance. MethodsFollowing PRISMA 2020 guidelines, and using LLM assistance, a systematic search of PubMed, Embase, Web of Science, Cochrane Library, and extensive grey literature sources, including over 3,000 theses, dissertations, clinical trial registries, and institutional reports, from inception to June 2025 was conducted. ResultsFrom an initial screen of over 25,000 records, 3,128 studies met the inclusion criteria, encompassing data from over 500,000 patients. Our analysis revealed distinct, germ-layer-specific PTM signatures and corresponding therapeutic vulnerabilities. Ectoderm-derived cancers (e.g., neuroblastoma, melanoma) are characterized by aberrant oncofetal glycosylation. Anti-GD2 immunotherapy, which targets a neural crest-specific glycan, demonstrated a profound survival benefit in high-risk neuroblastoma (Hazard Ratio for overall survival: 0.57, 95% CI 0.42-0.78, p<0.001). Mesoderm-derived malignancies (e.g., sarcomas, leukemias) exhibit dysregulated phosphorylation and SUMOylation. These cancers respond preferentially to kinase inhibitors (HR for overall survival: 0.72, 95% CI 0.68-0.76, p<0.001) and cellular therapies like CAR-T, which achieve overall response rates exceeding 80% in hematologic malignancies. Endoderm-derived adenocarcinomas (e.g., lung, colorectal) display a heightened dependency on the ubiquitin-proteasome system for managing proteotoxic stress, validating proteasome inhibitors (HR for overall survival: 0.77, 95% CI 0.71-0.84, p<0.001) and emerging PROTACs as key therapeutic classes. Implementation science analysis revealed profound global disparities, with treatment costs exceeding $450,000 per sequence and access to advanced PTM therapies below 5% in low-income countries. ConclusionThe post-translational modification landscape of cancer is fundamentally imprinted by its embryonic lineage, with the Golgi apparatus acting as a key arbiter of this oncofetal memory. This developmental framework provides a powerful new tool for rational drug design, biomarker discovery, and patient stratification. However, translating this scientific progress into global patient benefit requires timely and coordinated policy action to address the profound implementation chasm created by prohibitive costs and systemic inequities in healthcare access.

Diffuse midline glioma (DMG) is a leading cause of brain tumor death in children. In addition to hallmark H3.3K27M mutations, significant subsets also harbor alterations of other genes, such as TP53 and PDGFRA. Despite the prevalence of H3.3K27M, the results of clinical trials in DMG have been mixed, possibly due to the lack of models recapitulating its genetic heterogeneity. To address this gap, we developed human iPSC-derived tumor models harboring TP53R248Q with or without heterozygous H3.3K27M and/or PDGFRAD842V overexpression. The combination of H3.3K27M and PDGFRAD842V resulted in more proliferative tumors when gene-edited neural progenitor (NP) cells were implanted into mouse brains compared to NP with either mutation alone. Transcriptomic comparison of tumors and their NP cells of origin identified conserved JAK/STAT pathway activation across genotypes as characteristic of malignant transformation. Conversely, integrated genome-wide epigenomic and transcriptomic analyses, as well as rational pharmacologic inhibition, revealed targetable vulnerabilities unique to the TP53R248Q; H3.3K27M; PDGFRAD842V tumors and related to their aggressive growth phenotype. These include AREG-mediated cell cycle control, altered metabolism, and vulnerability to combination ONC201/trametinib treatment. Taken together, these data suggest that cooperation between H3.3K27M and PDGFRA influences tumor biology, underscoring the need for better molecular stratification in DMG clinical trials.

Mismatch repair deficient colorectal cancers have high mutation loads and many respond to immune checkpoint-inhibitors. We investigated how genetic and immune landscapes co-evolve in these tumors. All cases had high truncal mutation loads. Driver aberrations showed a clear hierarchy despite pervasive intratumor heterogeneity: Those in WNT/{beta}Catenin, mitogen-activated protein kinase and TGF{beta} receptor family genes were almost always truncal. Immune evasion drivers were predominantly subclonal and showed parallel evolution. Pan-tumor evolution, subclonal evolution, and evolutionary stasis of genetic immune evasion drivers defined three MMRd CRC subtypes with distinct T-cell infiltrates. These immune evasion drivers have been implicated in checkpoint-inhibitor resistance. Clonality and subtype assessments are hence critical for predictive immunotherapy biomarker development. Cancer cell PD-L1 expression was conditional on loss of the intestinal homeobox transcription factor CDX2. This explains infrequent PD-L1 expression by cancer cells and likely contributes to the high recurrence risk of MMRd CRCs with impaired CDX2 expression.

Due to their genetic instability, tumor cells bear mutations that can effectively be recognized by the immune system. In the clinic, immune checkpoint immunotherapy (ICI) can re-activate immune reactions against mutated proteins, known as neoantigens, leading to remarkable remission in cancer patients. Nevertheless, only a minority of patients are responsive to ICI, and approaches for prediction of responsiveness remain elusive yet are needed to improve the success of cancer treatments. While the tumor mutational burden (TMB) correlates positively with responsiveness and survival of patients undergoing ICI therapy, the influence of the subcellular localizations of the mutated proteins within the tumor cell has not been elucidated. Here, we hypothesized that the immune reactions are modulated by the localization of the mutated proteins and, therefore, that some subcellular localizations could favor responsiveness to ICI. We show in both a mouse melanoma model and human clinical datasets of 1722 ICI-treated patients that high membrane-localized tumor mutational burden (mTMB), particularly at the plasma membrane, correlate with responsiveness to ICI therapy and improved overall survival across multiple cancer types. We further highlight that mutations in the genes encoding for the membrane proteins NOTCH3, RNF43, NTRK3 and NOTCH1, among others, may serve as potent biomarkers to predict extended survival upon ICI in certain cancer types. We anticipate that our results will improve the predictability of cancer patient response to ICI and therefore may have important implications to establish future clinical guidelines to direct the choice of treatment toward ICI.

Real-world data suggest that SARS-CoV-2 mRNA vaccines, administered within 100 days of immune checkpoint inhibitor (ICI) treatment ("peri-ICI vaccination"), may improve ICI effectiveness, potentially through synergistic immune priming. Although peri-ICI vaccination was associated with longer survival when we applied a previous framework to our independent dataset, additional patterns emerged. Peri-ICI vaccination benefit diminished after 2021, a pattern confirmed in re-analysis of a published cohort. Benefit extended to patients treated with non-ICI antineoplastics. Benefit also dissipated in landmarked analyses restricted to periods of vaccine eligibility. Finally, progression-free survival in time periods with high vaccine uptake was not longer than in periods without vaccination. These analyses suggest peri-ICI vaccinations observed association with survival largely reflects selection bias in which patients with better prognosis were more likely to receive SARS-CoV-2 vaccines.

Linking glioblastoma (GBM) evolution to clinical progression is challenged by multiple factors, including tumor location for repeated sample collection, and short patient survival. In a single individual, we collected and analysed samples from 11 operations distributed across 31 months of multi-relapsing and multifocal GBM, including terminal leptomeningeal progression. All samples shared genomic ancestry of the retinoblastoma protein 1 (RB1) and neurofibromin 1 (NF1) mutations while advanced progression and extracranial metastases featured mutations of tuberous sclerosis complex 2 (TSC2), PBRM1, CD22 and Fanconi anemia supplementation group I (FANCI), correlated with clinical resistance to immunotherapies and DNA-damaging agents. Single-cell analytics revealed distinct yet reversible shifts in response to the precision medicine arsenal. GBM parenchymal dissemination and extracranial progression were associated with strengthening of neuron-like cell phenotypes. Our multidimensional study describes GBM evolution over a rarely reported time scale, and provides a valuable resource linking genetic, molecular, cellular and clinical progressions.

CDK4/6 inhibitors (CDK4/6i) have transformed the treatment of hormone receptor-positive (HR+), HER2-negative (HR+) breast cancers as they are effective across all clinicopathological, age, and ethnicity subgroups for metastatic HR+ breast cancer. In metastatic ER+ breast cancer, CDK4/6i lead to strong and consistent improvement in survival across different lines of therapy. To improve understanding of how metastatic HR+ breast cancers become refractory to CDK4/6i, we have created a multimodal and longitudinal tumor atlas to investigate therapeutic adaptations in malignant cells and in the tumor immune microenvironment. This atlas is part of the NCI Cancer Moonshot Human Tumor Atlas Network and includes seven pairs of pre- and on-progression biopsies from five metastatic HR+ breast cancer patients treated with CDK4/6i. Biopsies were profiled with bulk genomics, transcriptomics, and proteomics as well as single-cell ATAC-seq and multiplex tissue imaging for spatial, single-cell resolution. These molecular datasets were then linked with detailed clinical metadata to create an atlas for understanding tumor adaptations during therapy. Analysis of our atlas datasets suggests a diverse set of tumor adaptations to CDK4/6i therapy. Malignant cells may adapt to therapy via mTORC1 activation, cell cycle bypass, and increased replication stress. The tumor immune microenvironment displayed evidence of both immune activation and immune suppression during therapy. Together, our metastatic ER+ breast cancer atlas represents a rich multimodal resource to better understand HR+ breast cancer tumor therapeutic adaptations to CDK4/6i therapy.

Congenital DNA mismatch repair defects (dMMR), such as Lynch Syndrome, predispose patients to a variety of cancers and account for approximately 1% of glioblastoma cases. While few therapeutic options exist for glioblastoma, checkpoint blockade therapy has proven effective in dMMR tumors. Here we present a case study of a male in their 30s diagnosed with dMMR glioblastoma treated with pembrolizumab who experienced a partial response to therapy. Using a multiplex IHC analysis pipeline on archived slide specimens from tumor resections at diagnosis and after therapeutic interventions, we quantified changes in the frequency and spatial distribution of key cell populations in the tumor tissue. Notably, proliferating (KI67+) macrophages and T cells increased in frequency as did other KI67+ cells within the tumor. Therapeutic intervention remodeled the cellular spatial distribution in the tumor leading to a greater frequency of macrophage/tumor cell interactions and T cell/T cell interactions, highlighting impacts of checkpoint blockade on tumor cytoarchitecture and revealing spatial patterns that may indicate advantageous immune interactions in glioma and other solid tumors treated with these agents. InsightThis work sheds light on the capacity of checkpoint blockade therapy to modulate the immune microenvironment in DNA mismatch repair deficient glioblastoma, highlights the utility of window-of-opportunity clinical trials in patient selection of immunomodulatory therapies, and demonstrates the feasibility and utility of mapping cellular interactions associated with therapeutic responses in gliomas and other solid tumors. Statement regarding non-clinical trial statusWe confirmed with a treating neurologist in this case that the treatment received by the individual whose samples are studied was part of routine clinical care and not a clinical trial, as the patient was previously diagnosed with Lynch syndrome (a mismatch repair deficiency). The use of pembrolizumab is recommended for treatment of tumors with high mutational burden due to mismatch repair deficiency and is currently considered standard of care for these tumors. Additionally, though the intervention and outcome are detailed in the manuscript, the focus of the manuscript is on reporting changes observed in the immune microenvironment at different points in the clinical trajectory - a retrospective analysis performed after clinical care was complete.

Glioblastoma (GBM) is the most common and deadly primary brain cancer, with limited therapeutic options. Treatment failure has been associated with intratumoral heterogeneity and the acquisition of a pronounced mesenchymal-like (MES-L) phenotype after recurrence. Here, we have screened a panel of drugs with diverse mechanisms of action across two patient-derived glioblastoma stem cells (GSCs) to characterize the dynamics of drug-mediated transcriptomic cellular state changes. Our results demonstrate that anti-tumor drugs induce significant but reversible alterations in cellular state distribution at the single-cell level in a drug-specific manner, influencing transitions between mesenchymal and the neurodevelopmental astrocytic-like (AC-L) states. Utilizing barcoded analysis in our recently developed ex vivo glioblastoma cerebral organoid (GLICO) model, we discerned distinct cell state sensitivities to the MES-L enhancing histone deacetylase inhibitor, panobinostat, which are contingent on the inducible modulation of the mesenchymal transcription factor FOSL1. The strategic combination of MES-L enhancing and MES-l suppressing genetic perturbations or drugs significantly increases anti-glioma activity in a strategy we call state-selective lethality. Overall, our findings highlight the critical role of cell state plasticity in the response of GSCs to anti-tumor therapeutic stress and underscore the potential for novel GBM combination drug strategies.

High-grade gliomas (HGGs), including adult glioblastoma (GBM) and pediatric diffuse intrinsic pontine gliomas (DIPGs), are sustained by glioma stem cells (GSCs) that drive tumor initiation, therapeutic resistance, and recurrence. Although numerous prognostic models have been proposed, few are directly grounded in the core biology of GSCs across both adult and pediatric HGGs. In this study, we defined a GSC-associated gene signature by integrating transcriptomic profiles from patient-derived GSCs and their differentiated counterparts (in-house DIPG13 RNA-seq and public GSE54791 dataset). The biological relevance of this signature was confirmed through functional enrichment and protein-protein interaction analyses. To assess its prognostic value, we applied machine learning-based modeling in a large training cohort (Chinese Glioma Genome Atlas, CGGA) and validated the resulting model across three independent datasets (Gravendeel, Rembrandt, and an integrated pediatric HGG cohort), demonstrating consistent predictive performance. To enhance clinical applicability, we developed a nomogram that integrates the gene signature-derived risk score with key clinical factors (age, sex, race, and radiation therapy status), enabling individualized survival prediction. Collectively, this study establishes a biologically grounded, GSC-centered prognostic model for HGG that improves patient stratification and may inform personalized therapeutic strategies.

Lung cancer, the leading cause of cancer mortality, exhibits heterogeneity that enables adaptability, limits therapeutic success, and remains incompletely understood. Single-cell RNA sequencing (scRNAseq) of metastatic lung cancer was performed using 44 tumor biopsies obtained longitudinally from 27 patients before and during targeted therapy. Over 20,000 cancer and tumor microenvironment (TME) single-cell profiles exposed a rich and dynamic tumor ecosystem. scRNAseq of cancer cells illuminated targetable oncogenes beyond those detected clinically. Cancer cells surviving therapy as residual disease (RD) expressed an alveolar-regenerative cell signature suggesting a therapy-induced primitive cell state transition, whereas those present at on-therapy progressive disease (PD) upregulated kynurenine, plasminogen, and gap junction pathways. Active T-lymphocytes and decreased macrophages were present at RD and immunosuppressive cell states characterized PD. Biological features revealed by scRNAseq were biomarkers of clinical outcomes in independent cohorts. This study highlights how therapy-induced adaptation of the multi-cellular ecosystem of metastatic cancer shapes clinical outcomes.

PurposeCirculating-tumor DNA (ctDNA) is an emerging, minimally invasive diagnostic and prognostic biomarker for patients receiving a variety of cancer therapies. Comprehensive and robust longitudinal monitoring of ctDNA can provide an understanding of tumor burden, heterogeneity, and response or resistance to treatment. Experimental DesignctDNA of 28 metastatic cancer patients receiving an individualized neoantigen-directed immunotherapy was monitored longitudinally, up to two years, using a unique hybrid next generation sequencing assay targeting tumor-informed and tumor-naive variants. Patient-specific panels were designed targeting an average of 144 variants per patient. A tumor-naive universal panel was also designed for inclusion with patient-specific panels to monitor recurrently mutated tumor hotspots (e.g., KRAS and TP53) and genes implicated in immunotherapy resistance (B2M, TAP1/2). ResultsAnalytical characterization of the assay established linearity with a mean variant allele frequency (VAF) [&ge;]0.049%, and a variant-level limit of detection (LOD95) of 0.12%. Tumor-informed variants were detected in 26/28 patients, and de novo variants were observed in 25/28 patients. HLA LOH was also observed. Longitudinal ctDNA data provided key insights into patients responses to vaccine treatment. ConclusionsThe hybrid design of the ctDNA monitoring assay provides the sensitivity and specificity required for evaluating patient samples undergoing individualized therapy. It provides an improved capability to understand patient response to experimental therapies and further supports the utility of ctDNA as a cancer biomarker.

SARS-CoV-2 mRNA vaccination (COVID-19 vaccination) within 100 days of immune checkpoint inhibitor (ICI) treatment was reported to improve survival and prevent disease progression in patients with non-small cell lung cancer (NSCLC) and metastatic melanoma (Grippin et al., Nature, 2025). However, the clinical evidence, derived from real-world observational data, might suffer from methodological limitations, including immortal-time bias. These key limitations can be overcome by carefully designing a target trial emulation analysis. Using the data made publicly available by the authors, we emulated a target trial that would identify the causal effect of COVID-19 vaccination within 100 days of first ICI on overall survival and progression-free survival in patients with NSCLC and metastatic melanoma. In contrast to the original analysis, we found no evidence that COVID-19 vaccination improves survival outcomes in these populations. The original results likely reflect biases inherent to non-causal observational analyses. To clarify the true effect of COVID-19 vaccination in this setting, larger and suitably designed studies are needed.