JITC Digest June 2021

JITC Editor Picks

DNGR-1 limits Flt3L-mediated antitumor immunity by restraining tumor-infiltrating type I conventional dendritic cells

Journal for ImmunoTherapy of Cancer 2021;9:e002054 (12 May 2021)
Research

Summary:

DNGR-1 is a surface receptor on conventional type 1 dendritic cells (cDC1s) that recognizes F-actin exposed on necrotic cells leading to cross-presentation of dead cell-associated antigens and generation of tissue-resident CD8⁺ memory T cells after viral infection. Francisco J Cueto and colleagues demonstrate an unexpected inhibitory role for DNGR-1 in Flt3L-mediated anti-tumor immunity in the context of murine B16 melanoma and MC38 colorectal cancer models. Tumor growth kinetics at steady state were not altered by the loss of DNGR-1, nor was the loading of tumor antigens onto migratory or resident dendritic cells. Upon systemic Flt3L overexpression, however, tumors grew more slowly in DNGR-1-deficient mice. DNGR-1 deficiency led to increased numbers of intratumoral CD8⁺ T cells, but not CD4⁺ T cells. Flt3L overexpression in a DNGR-1-deficient background led to more pronounced intratumoral accumulation of CD103⁺ cDC1s without affecting infiltration by cDC2s and similar results were seen with exogenous DNGR-1 blockade via monoclonal antibodies. Expression of several gene sets related to cDC1 activation was enriched after Flt3L overexpression in DNGR-1-deficient mice, including tumor necrosis factor alpha signaling and inflammatory response markers, notably the chemomkines CCL5 and CCL3. Administration of the CCR5 signaling and migration response inhibitor maraviroc (originally developed to block HIV entry) along with Flt3L overexpression led to lower accumulation of cDC1s after DNGR-1 blockade. Cyclophosphamide, which increases serum Flt3L levels, also synergized with DNGR-1 deficiency, leading to delayed tumor growth. Analysis of The Cancer Genome Atlas (TCGA) datasets showed that patients with high coexpression of FLT3LG and CCL5 had longer overall survival compared with those intermediate and low expression levels. The findings identify DNGR-1 as a potential target to enhance intratumoral cDC1 infiltration and improve anti-tumor immunity in disease settings with high Flt3L expression.

NKTR-255, a novel polymer-conjugated rhIL-15 with potent antitumor efficacy

Research

Summary:

Despite strong mechanistic rationale for interleukin (IL)-15 as an immunotherapy via potent effects on NK and CD8⁺ T cell development and effector functions, recombinant versions of the cytokine displayed a mean plasma half-life of merely 2.5 hours in human trials, limiting clinical development. Takahiro Miyazaki et al confirm that NKTR-225, a novel polyethylene glycol-conjugated recombinant human IL-15 (rhIL-15) currently being evaluated in a phase I first-in-human trial (NCT04136756), shows similar in vitro activities to the parent cytokine with improved pharmacokinetic properties and anti-lymphoma activities in mouse models. A single dose of 0.3 mg/kg IV NKTR-225 had reduced clearance and longer half-life compared to rhIL-15 (2.31 mL/hour/kg vs 507 mL/hour/kg and 15.2 hours vs 0.168 hours, respectively). NKTR-255 and rhIL-15 induced STAT signaling with similar potency in NK and T cells. Rapid and sustained induction of phosphorylated STAT5 in NK and CD8⁺ T cells was seen after NKTR-225 stimulation with levels returning to baseline after 120 hours post-treatment compared to 6 hours post-treatment for rhIL-15. Multiple doses of NKTR-225 in vivo did not cause signs of tachyphylaxis, and the Ki67⁺ proliferating populations of NK and CD8⁺ T cells were increased in number with similar kinetics across repeated doses as after a single dose. In two independent efficacy studies in SCID mice bearing Daudi lymphoma xenografts, NKTR-255 reproducibly increased survival compared to treatment with pre-bound rhIL-15/IL-15 receptor complexes and rhIL-15 alone. Both treatment conditions induced comparable increases in granzyme B-expressing NK cells, yet NKTR-255 treatment led to durable and sustained effector production 6 days after treatment compared to the precomplexed cytokine. The results provide a framework for further development of rhIL-15-based immunotherapies.

Tumor hypoxia is associated with resistance to PD-1 blockade in squamous cell carcinoma of the head and neck

Dan P Zandberg, Ashley V Menk, Maria Velez, Daniel Normolle, Kristin DePeaux, Angen Liu, Robert L Ferris, Greg M Delgoffe
Journal for ImmunoTherapy of Cancer 2021;9:e002088 (13 May 2021)
Research

Summary:

Altered metabolism is increasingly becoming recognized as a key determinant of anti-tumor immunity. In the first examination of the metabolic effects of PD-1 blockade in the context of squamous cell carcinoma of the head and neck (HNSCC), Dan P Zandberg et al show that the development of immunotherapy resistance is accompanied by an upregulation of oxidative phosphorylation along with a concomitant increase in intratumoral hypoxia. Anti-PD-1 resistant tumors were generated by serial passage of a murine tonsillar epithelial cell line stably expressing E6, E7 and H-Ras (MEER). Seahorse technology showed that anti-PD-1 resistant MEER had significantly higher oxidative metabolism than the parental cell lines, which coincided with significantly increased intratumoral hypoxia as assayed by in vivo pimonidazole tracing. In tissue samples biobanked from 36 human patients with relapsed/metastatic HNSCC treated with anti-PD-1, the ratio of percent area to mean intensity of carbonic anhydrase IX in tumor as a measure of hypoxia (CAIX/I) as well as the CD8⁺/Treg ratio were both significantly associated with disease control in multivariate analysis. Low CAIX/I was also significantly associated with improved PFS and OS in univariate analysis. The study not only identifies tumor hypoxia as a predictive biomarker, but also identifies potential targets to enhance responses to PD-1 blockade.

Single-cell multiomics dissection of basal and antigen-specific activation states of CD19-targeted CAR T cells

Summary:

Autologous CD19-targeting chimeric antigen receptor (CAR) T cells have become integrated into standard care for relapsed or refractory hematologic malignancies, yet despite impressive initial response rates, recurrent disease remains common in a substantial fraction of patients. To characterize the molecular underpinnings associated with disparate clinical outcomes after CAR T cell therapy, Zhiliang Bai and colleagues performed single cell RNA sequencing in conjunction with the highly multiplexed protein marker detection and transcriptomics platform CITE-seq on 23,349 single 4-1BB costimulated second generation CAR T cells (ie, tisagenlecleucel) generated from one healthy donor (HD) as well as two patients with acute lymphoblastic leukemia, one of whom had minimal residual disease negative complete remission (CR) after treatment and one of whom who had non-responsive disease (NR). Unsupervised clustering analysis showed that a majority of HD- or CR-derived resting CAR T cells had predominantly stem cell-like memory or central memory differentiation status, whereas an effector memory phenotype was prevalent in NR-derived cells. Compared to the NR-derived CAR T cells, HD and CR cells had higher expression of oxidative phosphorylation-related genes and decreased glycolysis as well as fatty acid oxidation metabolism. Notable differences in major histocompatibility locus class II upregulation were observed between HD and CR cells. After co-culture with CD19-expressing cells, NR cells exhibited upregulation of exhaustion markers and glycolysis, whereas HD cells showed an even more pronounced activation signature compared with CR cells. Similar patterns were seen in published single cell RNA sequencing datasets from 4-1BB costimulated CD19 CAR T cells under similar experimental conditions. Cytokine production and effector function was independent of expression for the gene that encodes GM-CSF—a factor that has been implicated in cytokine release syndrome—across all samples. Furthermore, analysis of HD-derived CD28 costimulated CD19 CAR T cells (ie, axicabtagene ciloleucel) highlighted enhanced central memory and stem cell-like memory phenotypes in the 4-1BB costimulated products at baseline. The findings reveal functional, phenotypic, and metabolic differences in CAR T cells correlated with clinical outcomes and provide rationale for further development of “off the shelf” CAR T cell products.

Spotlight on Cancer Immunotherapy Journals

Journal for ImmunoTherapy of Cancer

Cancer Immunology, Immunotherapy

Cancer Immunology Research*

Journal of Immunotherapy

Immuno-Oncology and Technology (IOTECH)

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