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JAK-STAT-activated, fratricide-resistant CAR-T cells targeting membrane-bound TNF effectively treat AML and solid tumors

Summary:

This paper is from Keio University School of Medicine in Japan, senior authored by Yuki Kagoya. Finding suitable CAR-T targets for both hematopoietic and solid tumors remains a challenge. Although acute myeloid leukemia (AML) has been targeted with CD33 and CD123 CAR-Ts, there is still room for innovation to target other molecules. Here, the authors have taken an established CAR-T target, the N-terminal fragment of tumor necrosis factor (TNF-NTF), for B-cell malignancies and multiple myeloma and applied it to AML and an ovarian tumor in vivo. TNF normally exists when produced as a transmembrane molecule, cleaved enzymatically leaving the TNF-NTF behind, thereby marking the cell. Here, the authors generated monoclonal antibodies to the TNF-NTF that could be engineered into a CAR-T construct. Furthermore, when soluble TNF is produced by AML, this can suppress normal hematopoiesis and enable expansion of the malignant clone. The authors have taken a couple of imaginative steps, knocking out TNF in the CAR-T using CRISPR/Cas9 to limit fratricide (although diminishing cytotoxicity). In addition, they promoted cell growth and survival in vivo by engineering a chimeric receptor for extracellular IL-6, signaling intracellularly with the IL-7Rα chain. This promoted JAK/STAT signaling constitutively. When applied to either the THP1-GL leukemia model or a TNF-secreting ovarian cancer, this engineered CAR-T could drive control of tumor. It seems that a variety of tumor types, but especially ovarian and endometrial cancer, can secrete TNF and thus might be additional solid tumor targets for this approach. 

Disruption of cell-intrinsic PCSK9 enhances the antitumor efficacy of CD8⁺ T cells

Targeting HK3 in tumor-associated macrophages enhances antitumor immunity through augmenting antigen cross-presentation in cervical cancer

This paper, too, is from China, Wuhan and Hangzhou, demonstrating that a proximal enzyme important in glycolysis, hexokinase 3 (HK3), plays a critical role in also suppressing cross-presentation in tumor associated macrophages (TAMs). Although expression of HK3 in TAMs in cervical cancer in 119 patients that they examined was associated with greater T-cell infiltrate, it was also associated with worse prognosis. It also progressively increased in precursor cervical intraepithelial neoplasia lesion through to its greatest expression in overt tumors. Furthermore, CD163, MRC1, MS4A4A, TREM2, the fibrosis-related gene FN1, and the angiogenesis-associated gene ACE were found in TAMs. When HK3 is knocked down in the myeloid THP-1 cells, upregulation of important immunostimulatory genes, including CD80, CD86, and NOS2, was found. HK3^high macrophages demonstrated increased expression of lysosomal markers (LAMP1, LAMP2, CTSL, CTSB) and downregulation of proteasomal proteins (PSME1, PSMB8, PSMB9), consistent with it enhancing lysosomal protein degradation and limiting antigen cross-presentation. There are currently no available small molecule drugs nor targeted protein degraders available for this target, but metformin, a widely available and applied therapeutic, diminishes expression in TAMs, and when applied in murine tumor models, mediated important antitumor effects alone and in combination with immune checkpoint blockade.

MIAT promotes tumor-infiltrating CD8⁺ T-cell exhaustion and malignant progression of renal cell carcinoma via activating JAK3/STAT3 pathway

Summary: 

The multi-site authors from Beijing, Guangzhou, Ji’an, and Hangzhou screened 66 long non-coding RNAs (lnRNA) for their expression in tumors harboring exhausted T cells in patients with renal cell carcinoma. They identified the so-called “myocardial infarction associated transcript,” or MIAT, as being associated with exhaustion, and when high, associated with poor prognosis. Also known as Gomafu or RNCR2, MIAT is one of the lnRNAs which are generally >200 nucleotides and RNA polymerase II transcripts, mostly expressed in the nucleus. MIAT has 5 exons and a molecular length of 30,051 bases. It is, as its name suggests, highly expressed in the setting of myocardial infraction but also upregulated in ischemic stroke, neuroendocrine prostate cancer, non-small cell lung cancer, diabetic cardiomyopathy, cataract, chronic chagas disease cardiomyopathy, chronic lymphocytic leukemia, and down-regulated in schizophrenia, diabetic nephropathy, and bone disease. The investigators showed that MIAT in renal cell carcinoma with exhausted CD8⁺ T cells was associated with ETS1 and the JAK3 promoter, forming a trimeric complex to promote JAK3/STAT3 activation in the tumor. Less clear was the downstream mechanisms by which this led to T cell exhaustion, but it was positively correlated with expression of PD1, LAG3, and TIGIT in associated T cells. The MIAT-low group were more responsive to nivolumab in randomized studies previously performed and compared with everolimus administration. Furthermore, when examining MIAT expression and its knockdown in renal cancer lines, they showed in murine models that they could reduce T cell exhaustion. Using MIAT as a prognostic factor and as a potential target in emergent therapies seems promising.