T-cell help in the tumor microenvironment enhances rituximab-mediated NK-cell ADCC.

ABSTRACT: Rituximab (RTX) and other monoclonal antibodies (mAbs) that bind directly to malignant cells are of great clinical value but are not effective for all patients. A major mechanism of action of RTX is antibody-dependent cellular cytotoxicity (ADCC) mediated by natural killer (NK) cells. Prior in vitro studies in our laboratory demonstrated that T cells contribute to maintaining the viability and cytotoxic potential of NK cells activated by anti-CD20-coated target B cells. Here, we conducted studies using a novel mouse model and clinical correlative analysis to assess whether T-cell help contribute to RTX-mediated NK-cell ADCC in the tumor microenvironment (TME) in vivo. A humanized mouse model was developed using Raji lymphoma cells and normal donor peripheral blood mononuclear cells that allows for control of T-cell numbers in the lymphoma TME. In this model, NK-cell viability and CD16 and CD25 expression dropped after RTX in the absence of T cells but increased in the presence of T cells. RTX therapy was more effective when T cells were present and was ineffective when NK cells were depleted. In patients with indolent lymphoma, fine needle aspirates were obtained before and ∼1 week after treatment with a RTX-containing regimen. There was a strong correlation between CD4+ T cells as well as total T cells in the pretherapy TME and an increase in NK-cell CD16 and CD25 expression after RTX. We conclude that T-cell help in the TME enhances RTX-mediated NK-cell viability and ADCC.

The Lymphoma Epidemiology of Outcomes cohort study: Design, baseline characteristics, and early outcomes.

To address the current and long-term unmet health needs of the growing population of non-Hodgkin lymphoma (NHL) patients, we established the Lymphoma Epidemiology of Outcomes (LEO) cohort study (NCT02736357; https://leocohort.org/). A total of 7735 newly diagnosed patients aged 18 years and older with NHL were prospectively enrolled from 7/1/2015 to 5/31/2020 at 8 academic centers in the United States. The median age at diagnosis was 62 years (range, 18-99). Participants came from 49 US states and included 538 Black/African-Americans (AA), 822 Hispanics (regardless of race), 3386 women, 716 age <40 years, and 1513 rural residents. At study baseline, we abstracted clinical, pathology, and treatment data; banked serum/plasma (N = 5883, 76.0%) and germline DNA (N = 5465, 70.7%); constructed tissue microarrays for four major NHL subtypes (N = 1189); and collected quality of life (N = 5281, 68.3%) and epidemiologic risk factor (N = 4489, 58.0%) data. Through August 2022, there were 1492 deaths. Compared to population-based SEER data (2015-2019), LEO participants had a similar distribution of gender, AA race, Hispanic ethnicity, and NHL subtype, while LEO was underrepresented for patients who were Asian and aged 80 years and above. Observed overall survival rates for LEO at 1 and 2 years were similar to population-based SEER rates for indolent B-cell (follicular and marginal zone) and T-cell lymphomas, but were 10%-15% higher than SEER rates for aggressive B-cell subtypes (diffuse large B-cell and mantle cell). The LEO cohort is a robust and comprehensive national resource to address the role of clinical, tumor, host genetic, epidemiologic, and other biologic factors in NHL prognosis and survivorship.

The T Cell Immunoscore as a Reference for Biomarker Development Utilizing Real-World Data from Patients with Advanced Malignancies Treated with Immune Checkpoint Inhibitors.

BACKGROUND: We aimed to determine the prognostic value of an immunoscore reflecting CD3+ and CD8+ T cell density estimated from real-world transcriptomic data of a patient cohort with advanced malignancies treated with immune checkpoint inhibitors (ICIs) in an effort to validate a reference for future machine learning-based biomarker development. METHODS: Transcriptomic data was collected under the Total Cancer Care Protocol (NCT03977402) Avatar® project. The real-world immunoscore for each patient was calculated based on the estimated densities of tumor CD3+ and CD8+ T cells utilizing CIBERSORTx and the LM22 gene signature matrix. Then, the immunoscore association with overall survival (OS) was estimated using Cox regression and analyzed using Kaplan-Meier curves. The OS predictions were assessed using Harrell's concordance index (C-index). The Youden index was used to identify the optimal cut-off point. Statistical significance was assessed using the log-rank test. RESULTS: Our study encompassed 522 patients with four cancer types. The median duration to death was 10.5 months for the 275 participants who encountered an event. For the entire cohort, the results demonstrated that transcriptomics-based immunoscore could significantly predict patients at risk of death (p-value < 0.001). Notably, patients with an intermediate-high immunoscore achieved better OS than those with a low immunoscore. In subgroup analysis, the prediction of OS was significant for melanoma and head and neck cancer patients but did not reach significance in the non-small cell lung cancer or renal cell carcinoma cohorts. CONCLUSIONS: Calculating CD3+ and CD8+ T cell immunoscore using real-world transcriptomic data represents a promising signature for estimating OS with ICIs and can be used as a reference for future machine learning-based biomarker development.

Disparate groups share cancer disparities.

Due to historical and structural factors, underserved rural and racial/ethnic minorities suffer a disproportionate cancer burden based in part on common disparities they share. The time is ripe for cancer researchers to engage with these underserved populations to build trust in science and improve care for those they serve.

T cells, particularly activated CD4+ cells, maintain anti-CD20-mediated NK cell viability and antibody dependent cellular cytotoxicity.

Anti-CD20 monoclonal antibody (mAb) therapy is a mainstay of therapy for B cell malignancies, however many patients fail to respond or eventually develop resistance. The current understanding of mechanisms responsible for this resistance is limited. When peripheral blood mononuclear cells of healthy donors were cultured with Raji cells for 7 days, rituximab (RTX) induced NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC), enhanced NK cell viability and increased or maintained NK expression of CD56, CD16, CD57 and KIR. T cells, mainly CD4+, mediated these changes in a contact-dependent manner, with local T cell production of IL2 playing a central role. Similar findings were found when autologous B cells were used as target cells demonstrating the need for T cell help was not due to allogenic reaction. Results with other anti-CD20 and anti-EGFR antibodies were consistent. Small numbers of T cells activated by anti-CD3/CD28 beads or bispecific antibody enhanced RTX-mediated NK cell ADCC, viability and phenotypical changes. Pathway analysis of bulk NK cell mRNA sequencing after activation by RTX with and without T cells was consistent with T cells maintaining the viability of the activated NK cells. These findings suggest T cell help, mediated in large part by local production of IL2, contributes to NK cell ADCC and viability, and that activating T cells in the tumor microenvironment, such as through the use of anti-CD3 based bispecific antibodies, could enhance the efficacy of anti-CD20 and other mAb therapies where NK-mediated ADCC is a primary mechanism of action.

Bispecific antibody-activated T cells enhance NK cell-mediated antibody-dependent cellular cytotoxicity.

Resistance to anti-cancer monoclonal antibody (mAb) therapy remains a clinical challenge. Previous work in our laboratory has shown that T cell help in the form of interleukin-2 maintains long-term NK cell viability and NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC). Lack of such T cell help may be a potential mechanism for resistance to mAb therapy. Here, we evaluate whether concomitant treatment with anti-CD3 × anti-cancer bispecific antibodies (bsAbs) can overcome this resistance by enhancing T cell help, and thereby maintaining long-term NK cell-mediated ADCC. Normal donor peripheral blood mononuclear cells were depleted of T cells, replenished with defined numbers of autologous T cells (from 0.75 to 50%) and co-cultured with mono-/bispecific antibody-treated target tumor cells for up to 7 days. At low T cell concentrations, bsAb-activated T cells (mainly CD4+ T cells) were more effective than resting T cells at maintaining NK cell viability and ADCC. Brief (4 h to 2 day) bsAb exposure was sufficient to enhance long-term ADCC by NK cells. These findings raise the hypothesis that local T cell activation mediated by systemic treatment with anti-CD3 X anti-cancer bsAb may enhance the anti-tumor efficacy of monospecific mAbs that mediate their primary therapeutic effect via NK-mediated ADCC.

Monocytes Exposed to Immune Complexes Reduce pDC Type 1 Interferon Response to Vidutolimod.

Vidutolimod, also known as CMP-001, is a virus-like particle composed of the Qß bacteriophage coat protein encasing a TLR9 agonist. Vidutolimod injected intratumorally is showing promise in early phase clinical trials based on its ability to alter the tumor microenvironment and induce an anti-tumor immune response. We previously demonstrated that the in vivo efficacy of vidutolimod is dependent on the presence of anti-Qß antibodies that enhance opsonization and uptake of vidutolimod by TLR9-expressing plasmacytoid dendritic cells (pDCs). Here, we evaluated the effect of immune complexes, including anti-Qß-coated vidutolimod, on induction of Type 1 Interferon production by peripheral blood mononuclear cells in response to vidutolimod and soluble TLR9 agonists. Immune complexes, including but not limited to anti-Qß-coated vidutolimod, indirectly suppressed TLR9-mediated Type 1 Interferon production by pDCs in a monocyte-dependent manner. These findings indicate that anti-Qß-coated vidutolimod has effects in addition to those mediated by TLR9 that could have important clinical implications for understanding the mechanism of action of this exciting new approach to in situ immunization and cancer immunotherapy.

Prospective correlation between the patient microbiome with response to and development of immune-mediated adverse effects to immunotherapy in lung cancer.

BACKGROUND: Though the gut microbiome has been associated with efficacy of immunotherapy (ICI) in certain cancers, similar findings have not been identified for microbiomes from other body sites and their correlation to treatment response and immune related adverse events (irAEs) in lung cancer (LC) patients receiving ICIs. METHODS: We designed a prospective cohort study conducted from 2018 to 2020 at a single-center academic institution to assess for correlations between the microbiome in various body sites with treatment response and development of irAEs in LC patients treated with ICIs. Patients must have had measurable disease, ECOG 0-2, and good organ function to be included. Data was collected for analysis from January 2019 to October 2020. Patients with histopathologically confirmed, advanced/metastatic LC planned to undergo immunotherapy-based treatment were enrolled between September 2018 and June 2019. Nasal, buccal and gut microbiome samples were obtained prior to initiation of immunotherapy +/- chemotherapy, at development of adverse events (irAEs), and at improvement of irAEs to grade 1 or less. RESULTS: Thirty-seven patients were enrolled, and 34 patients were evaluable for this report. 32 healthy controls (HC) from the same geographic region were included to compare baseline gut microbiota. Compared to HC, LC gut microbiota exhibited significantly lower α-diversity. The gut microbiome of patients who did not suffer irAEs were found to have relative enrichment of Bifidobacterium (p = 0.001) and Desulfovibrio (p = 0.0002). Responders to combined chemoimmunotherapy exhibited increased Clostridiales (p = 0.018) but reduced Rikenellaceae (p = 0.016). In responders to chemoimmunotherapy we also observed enrichment of Finegoldia in nasal microbiome, and increased Megasphaera but reduced Actinobacillus in buccal samples. Longitudinal samples exhibited a trend of α-diversity and certain microbial changes during the development and resolution of irAEs. CONCLUSIONS: This pilot study identifies significant differences in the gut microbiome between HC and LC patients, and their correlation to treatment response and irAEs in LC. In addition, it suggests potential predictive utility in nasal and buccal microbiomes, warranting further validation with a larger cohort and mechanistic dissection using preclinical models. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03688347 . Retrospectively registered 09/28/2018.

Overcoming PD-1 Blockade Resistance with CpG-A Toll-Like Receptor 9 Agonist Vidutolimod in Patients with Metastatic Melanoma.

Patients with advanced melanoma that is resistant to PD-1 blockade therapy have limited treatment options. Vidutolimod (formerly CMP-001), a virus-like particle containing a CpG-A Toll-like receptor 9 (TLR9) agonist, may reverse PD-1 blockade resistance by triggering a strong IFN response to induce and attract antitumor T cells. In the dose-escalation part of this phase Ib study, vidutolimod was administered intratumorally at escalating doses with intravenous pembrolizumab to 44 patients with advanced melanoma who had progressive disease or stable disease on prior anti-PD-1 therapy. The combination of vidutolimod and pembrolizumab had a manageable safety profile, and durable responses were observed in 25% of patients, with tumor regression in both injected and noninjected lesions, including visceral lesions. Patients who responded to vidutolimod and pembrolizumab had noninflamed tumors at baseline and induction of an IFNγ gene signature following treatment, as well as increased systemic expression of the IFN-inducible chemokine CXCL10. SIGNIFICANCE: In this phase Ib study in patients with advanced melanoma, intratumoral TLR9 agonist vidutolimod in combination with pembrolizumab had a manageable safety profile and showed promising clinical activity, supporting the further clinical development of vidutolimod to overcome PD-1 blockade resistance through induction of an IFN response. See related commentary by Sullivan, p. 2960. This article is highlighted in the In This Issue feature, p. 2945.

Direct and indirect immune effects of CMP-001, a virus-like particle containing a TLR9 agonist.

BACKGROUND: CMP-001, also known as vidutolimod, is a virus-like particle containing a TLR9 agonist that is showing promise in early clinical trials. Our group previously demonstrated that the immunostimulatory effects of CMP-001 are dependent on an anti-Qß antibody response which results in opsonization of CMP-001 and uptake by plasmacytoid dendritic cells (pDCs) that then produce interferon (IFN)-α. IFN-α then leads to an antitumor T-cell response that is responsible for the in vivo efficacy of CMP-001. Here, we explore mechanisms by which the initial effects of CMP-001 on pDCs activate other cells that can contribute to development of an antitumor T-cell response. METHODS: Uptake of CMP-001 by various peripheral blood mononuclear cell (PBMC) populations and response to anti-Qß-coated CMP-001 were evaluated by flow cytometry and single-cell RNA sequencing. Purified monocytes were treated with anti-Qß-coated CMP-001 or recombinant IFN-α to evaluate direct and secondary effects of anti-Qß-coated CMP-001 on monocytes. RESULTS: Monocytes had the highest per cell uptake of anti-Qß-coated CMP-001 with lower levels of uptake by pDCs and other cell types. Treatment of PBMCs with anti-Qß-coated CMP-001 induced upregulation of IFN-responsive genes including CXCL10, PDL1, and indoleamine-2,3-dioxygenase (IDO) expression by monocytes. Most of the impact of anti-Qß-coated CMP-001 on monocytes was indirect and mediated by IFN-α, but uptake of anti-Qß-coated CMP-001 altered the monocytic response to IFN-α and resulted in enhanced expression of PDL1, IDO, and CD80 and suppressed expression of CXCL10. These changes included an enhanced ability to induce autologous CD4 T-cell proliferation. CONCLUSIONS: Anti-Qß-coated CMP-001 induces IFN-α production by pDCs which has secondary effects on a variety of cells including monocytes. Uptake of anti-Qß-coated CMP-001 by monocytes alters their response to IFN-α, resulting in enhanced expression of PDL1, IDO and CD80 and suppressed expression of CXCL10. Despite aspects of an immunosuppressive phenotype, these monocytes demonstrated increased ability to augment autologous CD4 T-cell proliferation. These findings shed light on the complexity of the mechanism of action of anti-Qß-coated CMP-001 and provide insight into pathways that may be targeted to further enhance the efficacy of this novel approach to immunotherapy.

Status of Cancer Care at Network Sites of the Nation's Academic Cancer Centers.

BACKGROUND: Cancer care coordination across major academic medical centers and their networks is evolving rapidly, but the spectrum of organizational efforts has not been described. We conducted a mixed-methods survey of leading cancer centers and their networks to document care coordination and identify opportunities to improve geographically dispersed care. METHODS: A mixed-methods survey was sent to 91 cancer centers in the United States and Canada. We analyzed the number and locations of network sites; access to electronic medical records (EMRs); clinical research support and participation at networks; use of patient navigators, care paths, and quality measures; and physician workforce. Responses were collected via Qualtrics software between September 2017 and December 2018. RESULTS: Of the 69 responding cancer centers, 74% were NCI-designated. Eighty-seven percent of respondents were part of a matrix health system, and 13% were freestanding. Fifty-six reported having network sites. Forty-three respondents use navigators for disease-specific populations, and 24 use them for all patients. Thirty-five respondents use ≥1 types of care path. Fifty-seven percent of networks had complete, integrated access to their main center's EMRs. Thirty-nine respondents said the main center provides funding for clinical research at networks, with 22 reporting the main center provides all funding. Thirty-five said the main center provided pharmacy support at the networks, with 15 indicating the main center provides 100% pharmacy support. Certification program participation varied extensively across networks. CONCLUSIONS: The data show academic cancer centers have extensive involvement in network cancer care, often extending into rural communities. Coordinating care through improved clinical trial access and greater use of patient navigation, care paths, coordinated EMRs, and quality measures is likely to improve patient outcomes. Although it is premature to draw firm conclusions, the survey results are appropriate for mapping next steps and data queries.

Immune checkpoint markers and anti-CD20-mediated NK cell activation.

Anti-CD20 mAb is an effective therapy for most B-cell malignancies. Checkpoint blockade has been used to enhance T-cell-mediated antitumor response. Little is known about the biologic significance of immune checkpoints expressed by NK cells in anti-CD20-based therapy. To investigate the role of checkpoints in anti-CD20-mediated NK cell biology, Raji B-cell lymphoma cells, and PBMCs from normal donors were cocultured with rituximab (RTX), obinutuzumab (OBZ), or trastuzumab as a control mAb for between 20 h and 9 d. RTX and OBZ induced a dose-dependent NK cell up-regulation of T-cell immunoreceptor with Ig and ITIM domain (TIGIT) and T-cell immunoglobulin mucin-3 (TIM3), but not PD1, CTLA4, or LAG3. Resting CD56dim NK had higher TIGIT and TIM3 expression than resting CD56bright NK although TIGIT and TIM3 were up-regulated on both subsets. NK cells with the CD16 158VV single nucleotide polymorphism had greater TIM3 up-regulation than did NK from VF or FF donors. TIGIT+ and TIM3+ NK cells degranulated, produced cytokines, and expressed activation markers to a greater degree than did TIGIT- or TIM3- NK cells. Blockade of TIGIT, TIM3, or both had little impact on RTX-induced NK cell proliferation, degranulation, cytokine production, or activation. Taken together, TIGIT and TIM3 can serve as markers for anti-CD20-mediated NK cell activation, but may not serve well as targets for enhancing the anti-tumor activity of such therapy.

The anti-tumor effects of cetuximab in combination with VTX-2337 are T cell dependent.

The Toll-like receptor 8 (TLR8) agonist VTX-2337 (motolimod) is an anti-cancer immunotherapeutic agent that is believed to augment natural killer (NK) and dendritic cell (DC) activity. The goal of this work is to examine the role of TLR8 expression/activity in head and neck squamous cell carcinoma (HNSCC) to facilitate the prediction of responders to VTX-2337-based therapy. The prognostic role of TLR8 expression in HNSCC patients was assessed by TCGA and tissue microarray analyses. The anti-tumor effect of VTX-2337 was determined in SCCVII/C3H, mEERL/C57Bl/6 and TUBO-human EGFR/BALB/c syngeneic mouse models. The effect of combined VTX-2337 and cetuximab treatment on tumor growth, survival and immune cell recruitment was assessed. TLR8 expression was associated with CD8+ T cell infiltration and favorable survival outcomes. VTX-2337 delayed tumor growth in all 3 syngeneic mouse models and significantly increased the survival of cetuximab-treated mice. The anti-tumor effects of VTX-2337+ cetuximab were accompanied by increased splenic lymphoid DCs and IFNγ+ CD4+ and tumor-specific CD8+ T cells. Depletion of CD4+ T cells, CD8+ T cells and NK cells were all able to abolish the anti-tumor effect of VTX-2337+ cetuximab. Altogether, VTX-2337 remains promising as an adjuvant for cetuximab-based therapy however patients with high TLR8 expression may be more likely to derive benefit from this drug combination compared to patients with low TLR8 expression.

Intraperitoneal CMP-001: A Novel Immunotherapy for Treating Peritoneal Carcinomatosis of Gastrointestinal and Pancreaticobiliary Cancer.

BACKGROUND: The treatment options for patients with peritoneal carcinomatosis (PC) of gastrointestinal and pancreaticobiliary origins are limited. The virus-like particle, CMP-001, composed of the Qß bacteriophage capsid protein encapsulating a CpG-A oligodeoxynucleotide, activates plasmacytoid dendritic cells (pDCs) and triggers interferon alpha (IFNα) release, leading to a cascade of anti-tumor immune effects. METHODS: To evaluate the ability of CMP-001 to trigger an immune response in patients with PC, peritoneal cells were isolated and stimulated ex vivo with CMP-001. Both IFNα release and percentage of pDC were quantified using enzyme-linked immunosorbent assay (ELISA) and flow cytometry, respectively. To evaluate the anti-tumor response in vivo, murine PC models were generated using mouse cancer cell lines (Panc02 and MC38) in immunocompetent mice treated with intraperitoneal CMP-001 or saline control. Survival was followed, and the immunophenotype of cells in the peritoneal tumor microenvironment was evaluated. RESULTS: The pDCs accounted for 1% (range 0.1-3.9%; n = 17) of the isolated peritoneal cells. Ex vivo CMP-001 stimulation of the peritoneal cells released an average of 0.77 ng/ml of IFNα (range, 0-4700 pg/ml; n = 14). The IFNα concentration was proportional to the percentage of pDCs present in the peritoneal cell mixture (r = 0.6; p = 0.037). In murine PC models, intraperitoneal CMP-001 treatment elicited an anti-tumor immune response including an increase in chemokines (RANTES and MIP-1ß), pro-inflammatory cytokines (IFNγ, interleukin 6 [IL-6], and IL-12), and peritoneal/tumor immune infiltration (CD4+/CD8+ T and natural killer [NK] cells). The CMP-001 treatment improved survival in both the Panc02 (median, 35 vs 28 days) and the MC38 (median: 57 vs 35 days) PC models (p < 0.05). CONCLUSIONS: As a novel immunotherapeutic agent, CMP-001 may be effective for treating patients with PC.

Quantification of Receptor Occupancy by Ligand-An Understudied Class of Potential Biomarkers.

Molecular complexes, such as ligand-receptor complexes, are vital for both health and disease and can be shed into the circulation in soluble form. Relatively little is known about the biology of soluble ligand-receptor complexes. The functional importance of such complexes and their potential use as clinical biomarkers in diagnosis and therapy remains underappreciated. Most traditional technologies used to study ligand-receptor complexes measure the individual levels of soluble ligands or receptors rather than the complexes themselves. The fraction of receptors occupied by ligand, and the potential clinical relevance of such information, has been largely overlooked. Here, we review the biological significance of soluble ligand-receptor complexes with a specific focus on their potential as biomarkers of cancer and other inflammatory diseases. In addition, we discuss a novel RNA aptamer-based technology, designated ligand-receptor complex-binding aptamers (LIRECAP), that can provide precise measurement of the fraction of a soluble receptor occupied by its ligand. The potential applicability of the LIRECAP technology as a biomarker discovery platform is also described.

In situ immunization of a TLR9 agonist virus-like particle enhances anti-PD1 therapy.

BACKGROUND: CMP-001 is a novel Toll-like receptor-9 agonist that consists of an unmethylated CpG-A motif-rich G10 oligodeoxynucleotide (ODN) encapsulated in virus-like particles. In situ vaccination of CMP-001 is believed to activate local tumor-associated plasmacytoid dendritic cells (pDCs) leading to type I interferon secretion and tumor antigen presentation to T cells and systemic antitumor T cell responses. This study is designed to investigate if CMP-001 would enhance head and neck squamous cell carcinoma (HNSCC) tumor response to anti-programmed cell death protein-1 (anti-PD-1) therapy in a human papilloma virus-positive (HPV+) tumor mouse model. METHODS: Immune cell activation in response to CMP-001±anti-Qß was performed using co-cultures of peripheral blood mononuclear cells and HPV+/HPV- HNSCC cells and then analyzed by flow cytometry. In situ vaccination with CMP-001 alone and in combination with anti-PD-1 was investigated in C57BL/6 mice-bearing mEERL HNSCC tumors and analyzed for anti-Qß development, antitumor response, survival and immune cell recruitment. The role of antitumor immune response due to CMP-001+anti-PD-1 treatment was investigated by the depletion of natural killer (NK), CD4+ T, and CD8+ T cells. RESULTS: Results showed that the activity of CMP-001 on immune cell (pDCs, monocytes, CD4+/CD8+ T cells and NK cells) activation depends on the presence of anti-Qß. A 2-week 'priming' period after subcutaneous administration of CMP-001 was required for robust anti-Qß development in mice. In situ vaccination of CMP-001 was superior to unencapsulated G10 CpG-A ODN at suppressing both injected and uninjected (distant) tumors. In situ vaccination of CMP-001 in combination with anti-PD-1 therapy induced durable tumor regression at injected and distant tumors and significantly prolonged mouse survival compared with anti-PD-1 therapy alone. The antitumor effect of CMP-001+anti-PD-1 was accompanied by increased interferon gamma (IFNγ)+ CD4+/CD8+ T cells compared with control-treated mice. The therapeutic and abscopal effect of CMP-001+ anti-PD-1 therapy was completely abrogated by CD8+ T cell depletion. CONCLUSIONS: These results demonstrate that in situ vaccination with CMP-001 can induce both local and abscopal antitumor immune responses. Additionally, the antitumor efficacy of CMP-001 combined with α-PD-1 therapy warrants further study as a novel immunotherapeutic strategy for the treatment of HNSCC.

A Genetic Screen to Identify Gain- and Loss-of-Function Modifications that Enhance T-cell Infiltration into Tumors.

T-cell-mediated cancer immunotherapies, including anti-PD-1 and T cells expressing chimeric antigen receptors (CAR-T cells), are becoming standard treatments for many cancer types. CAR-T therapy, in particular, has been successful in treating circulating, but not solid, tumors. One challenge limiting immunotherapy success is that tumors lacking T-cell infiltration do not respond to treatment. Therefore, one potential strategy to overcome resistance is to enhance the ability of T cells to traffic into tumors. Here, we describe an unbiased in vivo genetic screen approach utilizing the Sleeping Beauty mutagenesis system to identify candidate genes in T cells that might be modified to drive intratumoral T-cell accumulation. This screen identified over 400 candidate genes in three tumor models. These results indicated substantial variation in gene candidate selection, depending on the tumor model and whether or not mice were treated with anti-PD-1, yet some candidate genes were identified in all tumor models and with anti-PD-1 therapy. Inhibition of the most frequently mutated gene, Aak1, affected chemokine receptor expression and enhanced T-cell trafficking in vitro and in vivo Screen candidates should be further validated as therapeutic targets, with particular relevance to enhancing infiltration of adoptively transferred T cells into solid tumors.

Antibody Opsonization of a TLR9 Agonist-Containing Virus-like Particle Enhances In Situ Immunization.

The immunologic and therapeutic effects of intratumoral (IT) delivery of a novel virus-like particle as a lymphoma immunotherapy were evaluated in preclinical studies with human cells and a murine model. CMP-001 is a virus-like particle composed of the Qß bacteriophage capsid protein encapsulating an immunostimulatory CpG-A oligodeoxynucleotide TLR9 agonist. In vitro, CMP-001 induced cytokine production, including IFN-α from plasmacytoid dendritic cells, but only in the presence of anti-Qß Ab. In vivo, IT CMP-001 treatment of murine A20 lymphoma enhanced survival and reduced growth of both injected and contralateral noninjected tumors in a manner dependent on both the ability of mice to generate anti-Qß Ab and the presence of T cells. The combination of IT CMP-001 with systemic anti-PD-1 enhanced antitumor responses in both injected and noninjected tumors. IT CMP-001 alone or combined with anti-PD-1 augmented T cell infiltration in tumor-draining lymph nodes. We conclude IT CMP-001 induces a robust antitumor T cell response in an anti-Qß Ab-dependent manner and results in systemic antitumor T cell effects that are enhanced by anti-PD-1 in a mouse model of B cell lymphoma. Early-phase clinical evaluation of CMP-001 and anti-PD-1 combination therapy in lymphoma will begin shortly, based in part on these results.

Combining Doxorubicin-Loaded PEGylated Poly(Lactide-co-glycolide) Nanoparticles with Checkpoint Inhibition Safely Enhances Therapeutic Efficacy in a Melanoma Model.

Doxorubicin (DOX) has been widely used for the treatment of various cancers, however, the use of soluble DOX is limited by its low therapeutic index and improved formulations are therefore sought. Aside from its tumoricidal properties, DOX has also been shown to cause an immunogenic form of cell death, however, it is becoming abundantly clear that in situ immune stimulation alone is insufficient to cause significant immune based antitumor activity and that immune checkpoint modulation is also required. In this study, DOX-loaded nanoparticles were made by nanoprecipitation of DOX with a PEGylated poly(lactide-co-glycolide) copolymer (DOX-PLGA-PEG NPs) and were then tested in combination with immune checkpoint blockade (antiprogrammed death (anti-PD-1)) in a murine melanoma model to enhance antitumor effectiveness. Results showed the prepared particles to be approximately 134 nm in diameter (zeta potential -22 mV) with a loading of 1.75 µg DOX/mg NPs. In vitro release studies (of DOX) revealed the NPs to exhibit a 12 h burst release phase, followed by a slower release phase for up to 200 h. Survival studies of mice challenged with B16.F10 melanoma cells, revealed 60% of mice treated with the combination of DOX-PLGA-PEG NPs plus anti-PD-1 were tumor-free at the completion of the study. This combination therapy demonstrated higher antitumor efficacy in vivo compared to control, soluble DOX, and monotherapy of DOX-PLGA-PEG NPs or anti-PD-1 solution (p < 0.05). Moreover, in vivo safety studies (mouse weight/histopathological/toxicity) were investigated and results suggested that the combination therapy was safe. In conclusion, this study demonstrates the successful fabrication of DOX-loaded NPs by a nanoprecipitation method, and when combined with checkpoint inhibition could provide significant therapy in a murine melanoma model, suggesting that the DOX-PLGA-PEG NPs may be generating immune stimulation in situ and that benefit from this combination may be obtained in a clinical setting in the future.