Efficacy and Safety of the Melphalan/Hepatic Delivery System in Patients with Unresectable Metastatic Uveal Melanoma: Results from an Open-Label, Single-Arm, Multicenter Phase 3 Study.

BACKGROUND: Uveal melanoma (UM) has a poor prognosis once liver metastases occur. The melphalan/Hepatic Delivery System (melphalan/HDS) is a drug/device combination used for liver-directed treatment of metastatic UM (mUM) patients. The purpose of the FOCUS study was to assess the efficacy and safety of melphalan/HDS in patients with unresectable mUM. METHODS: Eligible patients with mUM received treatment with melphalan (3.0 mg/kg ideal body weight) once every 6 to 8 weeks for a maximum of six cycles. The primary end point was the objective response rate (ORR). The secondary end points included duration of response (DOR), overall survival (OS), and progression-free survival (PFS). RESULTS: The study enrolled 102 patients with mUM. Treatment was attempted in 95 patients, and 91 patients received treatment. In the treated population (n = 91), the ORR was 36.3 % (95 % confidence interval [CI], 26.44-47.01), including 7.7 % of patients with a complete response. Thus, the study met its primary end point because the lower bound of the 95 % CI for ORR exceeded the upper bound (8.3 %) from the benchmark meta-analysis. The median DOR was 14 months, and the median OS was 20.5 months, with an OS of 80 % at 1 year. The median PFS was 9 months, with a PFS of 65 % at 6 months. The most common serious treatment-emergent adverse events were thrombocytopenia (15.8 %) and neutropenia (10.5 %), treated mostly on an outpatient basis with observation. No treatment-related deaths were observed. CONCLUSION: Treatment with melphalan/HDS provides a clinically meaningful response rate and demonstrates a favorable benefit-risk profile in patients with unresectable mUM (study funded by Delcath; ClinicalTrials.gov identifier: NCT02678572; EudraCT no. 2015-000417-44).

The neo-open reading frame peptides that comprise the tumor framome are a rich source of neoantigens for cancer immunotherapy.

Identification of immunogenic cancer neoantigens as targets for therapy is challenging. Here, we integrate cancer whole genome and long-read transcript sequencing to identify the collection of novel open reading frame peptides (NOPs) expressed in tumors, termed the framome. NOPs represent tumor-specific peptides that are different from wild-type proteins and may be strongly immunogenic. We describe an uncharacterized class of hidden NOPs, which derive from structural genomic variants involving an upstream protein coding gene driving expression and translation of non-coding regions of the genome downstream of a rearrangement breakpoint. NOPs represent a vast amount of possible neoantigens particularly in tumors with many (complex) structural genomic variants and a low number of missense mutations. We show that NOPs are immunogenic and epitopes derived from NOPs can bind to MHC class I molecules. Finally, we provide evidence for the presence of memory T-cells specific for hidden NOPs in lung cancer patient peripheral blood.

Nilotinib in KIT-driven advanced melanoma: Results from the phase II single-arm NICAM trial.

Mucosal (MM) and acral melanomas (AM) are rare melanoma subtypes of unmet clinical need; 15%-20% harbor KIT mutations potentially targeted by small-molecule inhibitors, but none yet approved in melanoma. This multicenter, single-arm Phase II trial (NICAM) investigates nilotinib safety and activity in KIT mutated metastatic MM and AM. KIT mutations are identified in 39/219 screened patients (18%); of 29/39 treated, 26 are evaluable for primary analysis. Six patients were alive and progression free at 6 months (local radiology review, 25%); 5/26 (19%) had objective response at 12 weeks; median OS was 7.7 months; ddPCR assay correctly identifies KIT alterations in circulating tumor DNA (ctDNA) in 16/17 patients. Nilotinib is active in KIT-mutant AM and MM, comparable to other KIT inhibitors, with demonstrable activity in nonhotspot KIT mutations, supporting broadening of KIT evaluation in AM and MM. Our results endorse further investigations of nilotinib for the treatment of KIT-mutated melanoma. This clinical trial was registered with ISRCTN (ISRCTN39058880) and EudraCT (2009-012945-49).

INHBA is Enriched in HPV-negative Oropharyngeal Squamous Cell Carcinoma and Promotes Cancer Progression.

Patients with oropharyngeal squamous cell carcinoma (OPSCC) caused by human papilloma virus (HPV) exhibit a better prognosis than those with HPV-negative OPSCC. This study investigated the distinct molecular pathways that delineate HPV-negative from HPV-positive OPSCC to identify biologically relevant therapeutic targets. Bulk mRNA from 23 HPV-negative and 39 HPV-positive OPSCC tumors (n = 62) was sequenced to uncover the transcriptomic profiles. Differential expression followed by gene set enrichment analysis was performed to outline the top enriched biological process in the HPV-negative compared with HPV-positive entity. INHBA, the highest overexpressed gene in the HPV-negative tumor, was knocked down. Functional assays (migration, proliferation, cell death, stemness) were conducted to confirm the target's oncogenic role. Correlation analyses to reveal its impact on the tumor microenvironment were performed. We revealed that epithelial-to-mesenchymal transition (EMT) is the most enriched process in HPV-negative compared with HPV-positive OPSCC, with INHBA (inhibin beta A subunit) being the top upregulated gene. INHBA knockdown downregulated the expression of EMT transcription factors and attenuated migration, proliferation, stemness, and cell death resistance of OPSCC cells. We uncovered that INHBA associates with a pro-tumor microenvironment by negatively correlating with antitumor CD8+ T and B cells while positively correlating with pro-tumor M1 macrophages. We identified three miRNAs that are putatively involved in repressing INHBA expression. Our results indicate that the upregulation of INHBA is tumor-promoting. We propose INHBA as an attractive therapeutic target for the treatment of INHBA-enriched tumors in patients with HPV-negative OPSCC to ameliorate prognosis. SIGNIFICANCE: Patients with HPV-negative OPSCC have a poorer prognosis due to distinct molecular pathways. This study reveals significant transcriptomic differences between HPV-negative and HPV-positive OPSCC, identifying INHBA as a key upregulated gene in HPV-negative OPSCC's oncogenic pathways. INHBA is crucial in promoting EMT, cell proliferation, and an immunosuppressive tumor environment, suggesting its potential as a therapeutic target for HPV-negative OPSCC.

Intra-tumoral T cells in pediatric brain tumors display clonal expansion and effector properties.

Brain tumors in children are a devastating disease in a high proportion of patients. Owing to inconsistent results in clinical trials in unstratified patients, the role of immunotherapy remains unclear. We performed an in-depth survey of the single-cell transcriptomes and clonal relationship of intra-tumoral T cells from children with brain tumors. Our results demonstrate that a large fraction of T cells in the tumor tissue are clonally expanded with the potential to recognize tumor antigens. Such clonally expanded T cells display enrichment of transcripts linked to effector function, tissue residency, immune checkpoints and signatures of neoantigen-specific T cells and immunotherapy response. We identify neoantigens in pediatric brain tumors and show that neoantigen-specific T cell gene signatures are linked to better survival outcomes. Notably, among the patients in our cohort, we observe substantial heterogeneity in the degree of clonal expansion and magnitude of T cell response. Our findings suggest that characterization of intra-tumoral T cell responses may enable selection of patients for immunotherapy, an approach that requires prospective validation in clinical trials.

Tumor-Infiltrating CD103+ Tissue-Resident Memory T Cells and CD103-CD8+ T Cells in HNSCC Are Linked to Outcome in Primary but not Metastatic Disease.

PURPOSE: High numbers of tumor-infiltrating lymphocytes (TIL) are linked to better survival in patients with cancer. Tissue-resident memory T cells (TRM; CD8+CD103+) are recognized as a key player of anticancer immune response. To assess TRM cells in primary, metastatic, and recurrent head and neck squamous cell carcinoma (HNSCC), we developed a tissue microarray (TMA) and used multiplex IHC (MxIHC). EXPERIMENTAL DESIGN: Samples from primary tumors of 379 HNSCC cases treated at Southampton Hospitals between 2000 and 2016 were collected and analyzed. Of these, 105 cases had lymph node metastases and 82 recurrences. A TMA was generated with triplicate cores for each sample. MxIHC with a stain-and-strip approach was performed using CD8, CD103, and TIM3. Scanned slides were analyzed (digital image analysis) and quality checked (QC). RESULTS: After QC, 194 primary tumors, 76 lymph node metastases, and 65 recurrences were evaluable. Alcohol consumption was statistically significantly correlated with a reduction of TRM cells in primary tumors (nondrinker vs. heavy drinker: P = 0.0036). The known survival benefit of TRM cell infiltration in primary tumors was not found for lymph node metastasis. In recurrences, a high TRM cell number led to a favorable outcome after 12 months. The checkpoint molecule TIM3, was expressed significantly higher on TRM and non-TRM cells in the lymph node compared with primary tumors (P < 0.0001), which was also seen in recurrences (P = 0.0134 and P = 0.0007, respectively). CONCLUSIONS: We confirm the prognostic impact of TIL in primary tumors and in recurrences. TRM cell density in lymph node metastases was not linked to outcome. The role of TIM3, as a therapeutic target remains to be defined.

Human CD79b+ neutrophils in the blood are associated with early-stage melanoma.

Purpose: Due to their abundance in the blood, low RNA content, and short lifespan, neutrophils have been classically considered to be one homogenous pool. However, recent work has found that mature neutrophils and neutrophil progenitors are composed of unique subsets exhibiting context-dependent functions. In this study, we ask if neutrophil heterogeneity is associated with melanoma incidence and/or disease stage. Experimental design: Using mass cytometry, we profiled melanoma patient blood for unique cell surface markers among neutrophils. Markers were tested for their predictiveness using flow cytometry data and random forest machine learning. Results: We identified CD79b+ neutrophils (CD3-CD56-CD19-Siglec8-CD203c-CD86LoCD66b+CD79b+) that are normally restricted to the bone marrow in healthy humans but appear in the blood of subjects with early-stage melanoma. Further, we found CD79b+ neutrophils present in tumors of subjects with head and neck cancer. AI-mediated machine learning analysis of neutrophils from subjects with melanoma confirmed that CD79b expression among peripheral blood neutrophils is highly important in identifying melanoma incidence. We noted that CD79b+ neutrophils possessed a neutrophilic appearance but have transcriptional and surface-marker phenotypes reminiscent of B cells. Compared to remaining blood neutrophils, CD79b+ neutrophils are primed for NETosis, express higher levels of antigen presentation-related proteins, and have an increased capacity for phagocytosis. Conclusion: Our work suggests that CD79b+ neutrophils are associated with early-stage melanoma.

Transcriptomes and metabolism define mouse and human MAIT cell populations.

Mucosal-associated invariant T (MAIT) cells are a subset of T lymphocytes that respond to microbial metabolites. We defined MAIT cell populations in different organs and characterized the developmental pathway of mouse and human MAIT cells in the thymus using single-cell RNA sequencing and phenotypic and metabolic analyses. We showed that the predominant mouse subset, which produced IL-17 (MAIT17), and the subset that produced IFN-γ (MAIT1) had not only greatly different transcriptomes but also different metabolic states. MAIT17 cells in different organs exhibited increased lipid uptake, lipid storage, and mitochondrial potential compared with MAIT1 cells. All these properties were similar in the thymus and likely acquired there. Human MAIT cells in lung and blood were more homogeneous but still differed between tissues. Human MAIT cells had increased fatty acid uptake and lipid storage in blood and lung, similar to human CD8 T resident memory cells, but unlike mouse MAIT17 cells, they lacked increased mitochondrial potential. Although mouse and human MAIT cell transcriptomes showed similarities for immature cells in the thymus, they diverged more strikingly in the periphery. Analysis of pet store mice demonstrated decreased lung MAIT17 cells in these so-called "dirty" mice, indicative of an environmental influence on MAIT cell subsets and function.

Advancing Understanding of Non-Small Cell Lung Cancer with Multiplexed Antibody-Based Spatial Imaging Technologies.

Non-small cell lung cancer (NSCLC) remains a cause of significant morbidity and mortality, despite significant advances made in its treatment using immune checkpoint inhibitors (ICIs) over the last decade; while a minority experience prolonged responses with ICIs, benefit is limited for most patients. The development of multiplexed antibody-based (MAB) spatial tissue imaging technologies has revolutionised analysis of the tumour microenvironment (TME), enabling identification of a wide range of cell types and subtypes, and analysis of the spatial relationships and interactions between them. Such study has the potential to translate into a greater understanding of treatment susceptibility and resistance, factors influencing prognosis and recurrence risk, and identification of novel therapeutic approaches and rational treatment combinations to improve patient outcomes in the clinic. Herein we review studies that have leveraged MAB technologies to deliver novel insights into the TME of NSCLC.

Immunotherapy-related adverse events in real-world patients with advanced non-small cell lung cancer on chemoimmunotherapy: a Spinnaker study sub-analysis.

Background: The Spinnaker study evaluated survival outcomes and prognostic factors in patients with advanced non-small-cell lung cancer receiving first-line chemoimmunotherapy in the real world. This sub-analysis assessed the immunotherapy-related adverse effects (irAEs) seen in this cohort, their impact on overall survival (OS) and progression-free survival (PFS), and related clinical factors. Methods: The Spinnaker study was a retrospective multicentre observational cohort study of patients treated with first-line pembrolizumab plus platinum-based chemotherapy in six United Kingdom and one Swiss oncology centres. Data were collected on patient characteristics, survival outcomes, frequency and severity of irAEs, and peripheral immune-inflammatory blood markers, including the neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII). Results: A total of 308 patients were included; 132 (43%) experienced any grade irAE, 100 (32%) Grade 1-2, and 49 (16%) Grade 3-4 irAEs. The median OS in patients with any grade irAES was significantly longer (17.5 months [95% CI, 13.4-21.6 months]) than those without (10.1 months [95% CI, 8.3-12.0 months]) (p<0.001), either if Grade 1-2 (p=0.003) or Grade 3-4 irAEs (p=0.042). The median PFS in patients with any grade irAEs was significantly longer (10.1 months [95% CI, 9.0-11.2 months]) than those without (6.1 months [95% CI, 5.2-7.1 months]) (p<0.001), either if Grade 1-2 (p=0.011) or Grade 3-4 irAEs (p=0.036). A higher rate of irAEs of any grade and specifically Grade 1-2 irAEs correlated with NLR <4 (p=0.013 and p=0.018), SII <1,440 (p=0.029 ad p=0.039), response to treatment (p=0.001 and p=0.034), a higher rate of treatment discontinuation (p<0.00001 and p=0.041), and the NHS-Lung prognostic classes (p=0.002 and p=0.008). Conclusions: These results confirm survival outcome benefits in patients with irAEs and suggest a higher likelihood of Grade 1-2 irAEs in patients with lower NLR or SII values or according to the NHS-Lung score.

REFINE-Lung implements a novel multi-arm randomised trial design to address possible immunotherapy overtreatment.

Increasing evidence suggests that some immunotherapy dosing regimens for patients with advanced cancer could result in overtreatment. Given the high costs of these agents, and important implications for quality of life and toxicity, new approaches are needed to identify and reduce unnecessary treatment. Conventional two-arm non-inferiority designs are inefficient in this context because they require large numbers of patients to explore a single alternative to the standard of care. Here, we discuss the potential problem of overtreatment with anti-PD-1 directed agents in general and introduce REFINE-Lung (NCT05085028), a UK multicentre phase 3 study of reduced frequency pembrolizumab in advanced non-small-cell lung cancer. REFINE-Lung uses a novel multi-arm multi-stage response over continuous interventions (MAMS-ROCI) design to determine the optimal dose frequency of pembrolizumab. Along with a similarly designed basket study of patients with renal cancer and melanoma, REFINE-Lung and the MAMS-ROCI design could contribute to practice-changing advances in patient care and form a template for future immunotherapy optimisation studies across cancer types and indications. This new trial design is applicable to many new or existing agents for which optimisation of dose, frequency, or duration of therapy is desirable.

The Effects of GCSF Primary Prophylaxis on Survival Outcomes and Toxicity in Patients with Advanced Non-Small Cell Lung Cancer on First-Line Chemoimmunotherapy: A Sub-Analysis of the Spinnaker Study.

GCSF prophylaxis is recommended in patients on chemotherapy with a >20% risk of febrile neutropenia and is to be considered if there is an intermediate risk of 10−20%. GCSF has been suggested as a possible adjunct to immunotherapy due to increased peripheral neutrophil recruitment and PD-L1 expression on neutrophils with GCSF use and greater tumour volume decrease with higher tumour GCSF expression. However, its potential to increase neutrophil counts and, thus, NLR values, could subsequently confer poorer prognoses on patients with advanced NSCLC. This analysis follows on from the retrospective multicentre observational cohort Spinnaker study on advanced NSCLC patients. The primary endpoints were OS and PFS. The secondary endpoints were the frequency and severity of AEs and irAEs. Patient information, including GCSF use and NLR values, was collected. A secondary comparison with matched follow-up duration was also undertaken. Three hundred and eight patients were included. Median OS was 13.4 months in patients given GCSF and 12.6 months in those not (p = 0.948). Median PFS was 7.3 months in patients given GCSF and 8.4 months in those not (p = 0.369). A total of 56% of patients receiving GCSF had Grade 1−2 AEs compared to 35% who did not receive GCSF (p = 0.004). Following an assessment with matched follow-up, 41% of patients given GCSF experienced Grade 1−2 irAEs compared to 23% of those not given GCSF (p = 0.023). GCSF prophylaxis use did not significantly affect overall or progression-free survival. Patients given GCSF prophylaxis were more likely to experience Grade 1−2 adverse effects and Grade 1−2 immunotherapy-related adverse effects.

JAML immunotherapy targets recently activated tumor-infiltrating CD8+ T cells.

Junctional adhesion molecule-like protein (JAML) serves as a co-stimulatory molecule in γδ T cells. While it has recently been described as a cancer immunotherapy target in mice, its potential to cause toxicity, specific mode of action with regard to its cellular targets, and whether it can be targeted in humans remain unknown. Here, we show that JAML is induced by T cell receptor engagement, reveal that this induction is linked to cis-regulatory interactions between the CD3D and JAML gene loci. When compared with other immunotherapy targets plagued by low target specificity and end-organ toxicity, we find JAML to be mostly restricted to and highly expressed by tissue-resident memory CD8+ T cells in multiple cancer types. By delineating the key cellular targets and functional consequences of agonistic anti-JAML therapy in a murine melanoma model, we show its specific mode of action and the reason for its synergistic effects with anti-PD-1.

Single-cell analysis reveals prognostic fibroblast subpopulations linked to molecular and immunological subtypes of lung cancer.

Fibroblasts are poorly characterised cells that variably impact tumour progression. Here, we use single cell RNA-sequencing, multiplexed immunohistochemistry and digital cytometry (CIBERSORTx) to identify and characterise three major fibroblast subpopulations in human non-small cell lung cancer: adventitial, alveolar and myofibroblasts. Alveolar and adventitial fibroblasts (enriched in control tissue samples) localise to discrete spatial niches in histologically normal lung tissue and indicate improved overall survival rates when present in lung adenocarcinomas (LUAD). Trajectory inference identifies three phases of control tissue fibroblast activation, leading to myofibroblast enrichment in tumour samples: initial upregulation of inflammatory cytokines, followed by stress-response signalling and ultimately increased expression of fibrillar collagens. Myofibroblasts correlate with poor overall survival rates in LUAD, associated with loss of epithelial differentiation, TP53 mutations, proximal molecular subtypes and myeloid cell recruitment. In squamous carcinomas myofibroblasts were not prognostic despite being transcriptomically equivalent. These findings have important implications for developing fibroblast-targeting strategies for cancer therapy.

Transcriptional analysis highlights three distinct immune profiles of high-risk oral epithelial dysplasia.

Oral potentially malignant disorders (OPMD) are precursors of oral squamous cell carcinoma (OSCC), and the presence of oral epithelial dysplasia (OED) in OPMD confers an increased risk of malignant transformation. Emerging evidence has indicated a role for the immune system in OPMD disease progression; however, the underlying immune mechanisms remain elusive. In this study, we used immune signatures established from cancer to delineate the immune profiles of moderate and severe OED, which are considered high-risk OPMD. We demonstrated that moderate and severe OEDs exhibit high lymphocyte infiltration and upregulation of genes involved in both immune surveillance (major histocompatibility complex-I, T cells, B cells and cytolytic activity) and immune suppression (immune checkpoints, T regulatory cells, and tumor-associated macrophages). Notably, we identified three distinct subtypes of moderate and severe OED: immune cytotoxic, non-cytotoxic and non-immune reactive. Active immune surveillance is present in the immune cytotoxic subtype, whereas the non-cytotoxic subtype lacks CD8 immune cytotoxic response. The non-immune reactive subtype showed upregulation of genes involved in the stromal microenvironment and cell cycle. The lack of T cell infiltration and activation in the non-immune reactive subtype is due to the dysregulation of CTNNB1, PTEN and JAK2. This work suggests that moderate and severe OED that harbor the non-cytotoxic or non-immune reactive subtype are likely to progress to cancer. Overall, we showed that distinct immune responses are present in high-risk OPMD, and revealed targetable pathways that could lead to potential new approaches for non-surgical management of OED.

Efficacy outcomes and prognostic factors from real-world patients with advanced non-small-cell lung cancer treated with first-line chemoimmunotherapy: The Spinnaker retrospective study.

BACKGROUND: Efficacy outcomes and prognostic factors of real-world patients with advanced non-small cell lung cancer (aNSCLC) treated with first-line chemoimmunotherapy are still limited. PATIENTS AND METHODS: In the retrospective Spinnaker study, data was collected from patients in six United Kingdom and one Swiss oncology centres with first-line pembrolizumab plus platinum-based chemotherapy. Efficacy outcomes and potential prognostic factors were estimated aiming at developing a prognostic model. RESULTS: Three-hundred-eight patients were included, 32% ≥ 70 years, with ≥ 3 metastatic sites in 33%, brain or liver metastases in 10% and 12%, respectively. With a median follow-up of 18.0 months (mo.) (range, 15.9-20.1), median overall survival (OS) and progression-free survival (PFS) were 12.7 mo. (range, 10.2-15.2), and 8.0 mo. (range, 7.1-8.8), respectively. The neutrophils-to-lymphocytes ratio (NLR) and systemic immune-inflammatory index (SII) (i.e., NLR × platelet count) were both significantly higher in ECOG PS 1 (p = 0.0147 and p = 0.0018, respectively), underweight or normal body mass index (p = 0.0456 and p = 0.0062, respectively), ≥3 metastatic sites (p = 0.0069 and p = 0.112), pretreatment steroids (p = 0.0019 and p = 0.0017). By MVA, the number of metastatic sites ≥ 3 (p < 0.001 and p = 0.002), squamous histology (p = 0.033 and p = 0.013) and SII ≥ 1444 (p = 0.031 and p = 0.009, respectively) were associated with both worse OS and PFS and led to a highly discriminating three-class risk prognostic model. CONCLUSION: Real-world PFS with chemoimmunotherapy in aNSCLC patients is similar to that reported in clinical trials. A high number of metastatic sites, squamous histology and high SII are adverse prognostic factors that might contribute to a clinically useful prognostic model.

Appraising the Costs of Genomic Testing for Histology-Independent Technologies: An Illustrative Example for NTRK Fusions.

OBJECTIVES: Histology-independent (HI) technologies are authorized for patients with advanced or metastatic cancer if they express a particular biomarker regardless of its position in the body. Although this represents an important advancement in cancer treatment, genomic testing to identify eligible individuals for HI technologies will require substantial investment and impact their cost-effectiveness. Estimating these costs is complicated by several issues, which affect not only the overall cost of testing but also the distribution of testing costs across tumor types. METHODS: Key issues that should be considered when evaluating the cost of genomic testing to identify those eligible for HI technologies are discussed. These issues are explored in illustrative analyses where costs of genomic testing for NTRK fusions in England for recently approved HI technologies are estimated. RESULTS: The prevalence of mutation, testing strategy adopted, and current testing provision affect the cost of identifying eligible patients. The illustrative analysis estimated the cost of RNA-based next-generation sequencing to identify 1 individual with an NTRK fusion ranged between £377 and £282 258. To improve cost-effectiveness, testing costs could be shared across multiple technologies. An estimated additional ∼4000 patients would need to be treated with other HI therapies for testing in patients with advanced or metastatic cancer to be cost-effective. CONCLUSIONS: The cost of testing to identify individuals eligible for HI technologies affect the drug's cost-effectiveness. The cost of testing across tumor types varies owing to heterogeneity in the mutation's prevalence and current testing provision. The cost-effectiveness of HI technologies may be improved if testing costs could be shared across multiple agents.

Single-cell immune profiling reveals long-term changes in myeloid cells and identifies a novel subset of CD9+ monocytes associated with COVID-19 hospitalization.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can result in severe immune dysfunction, hospitalization, and death. Many patients also develop long-COVID-19, experiencing symptoms months after infection. Although significant progress has been made in understanding the immune response to acute SARS-CoV-2 infection, gaps remain in our knowledge of how innate immunity influences disease kinetics and severity. We hypothesized that cytometry by time-of-flight analysis of PBMCs from healthy and infected subjects would identify novel cell surface markers and innate immune cell subsets associated with COVID-19 severity. In this pursuit, we identified monocyte and dendritic cell subsets that changed in frequency during acute SARS-CoV-2 infection and correlated with clinical parameters of disease severity. Subsets of nonclassical monocytes decreased in frequency in hospitalized subjects, yet increased in the most severe patients and positively correlated with clinical values associated with worse disease severity. CD9, CD163, PDL1, and PDL2 expression significantly increased in hospitalized subjects, and CD9 and 6-Sulfo LacNac emerged as the markers that best distinguished monocyte subsets amongst all subjects. CD9+ monocytes remained elevated, whereas nonclassical monocytes remained decreased, in the blood of hospitalized subjects at 3-4 months postinfection. Finally, we found that CD9+ monocytes functionally released more IL-8 and MCP-1 after LPS stimulation. This study identifies new monocyte subsets present in the blood of COVID-19 patients that correlate with disease severity, and links CD9+ monocytes to COVID-19 progression.