Nanoscale CAR Organization at the Immune Synapse Correlates with CAR-T Effector Functions

T cells expressing chimeric antigen receptors (CARs) are at the forefront of clinical treatment of cancers. Still, the nanoscale organization of CARs at the interface of CAR-Ts with target cells, which is essential for TCR-mediated T cell activation, remains poorly understood. Here, we studied the nanoscale organization of CARs targeting CD138 proteoglycans in such fixed and live interfaces, generated optimally for single-molecule localization microscopy. CARs showed significant self-association in nanoclusters that was enhanced in interfaces with on-target cells (SKOV-3, CAG, FaDu) relative to negative cells (OVCAR-3). CARs also segregated more efficiently from the abundant membrane phosphatase CD45 in CAR-T cells forming such interfaces. CAR clustering and segregation from CD45 correlated with the effector functions of Ca++ influx and target cell killing. Our results shed new light on the nanoscale organization of CARs on the surfaces of CAR-Ts engaging on- and off-target cells, and its potential significance for CAR-Ts' efficacy and safety.

Comparing Intraperitoneal and Intravenous Personalized ErbB2CAR-T for the Treatment of Epithelial Ovarian Cancer

High-grade serous ovarian carcinoma (HGSOC) is the most common type of epithelial ovarian cancer. The majority of cases are diagnosed at advanced stages, when intraperitoneal (IP) spread has already occurred. Despite significant surgical and chemotherapeutic advances in HGSOC treatment over the past decades, survival rates with HGSOC have only modestly improved. Chimeric antigen receptor (CAR)-T cells enable T cells to directly bind to tumor-associated antigens in a major histocompatibility complex-independent manner, thereby inducing tumor rejection. While CAR-T cell therapy shows great promise in hematological malignancies, its use in solid tumors is limited. Therefore, innovative approaches are needed to increase the specificity of CAR-modified T cells against solid tumors. The aim of this study was to assess the efficacy and safety of intraperitoneal (IP) versus intravenous (IV) CAR-T cell therapy in the treatment of HGSOC. We constructed a CAR that targets the ErbB2/HER2 protein (ErbB2CAR), which is overexpressed in HGSOC, and evaluated the functionality of ErbB2CAR on ovarian cancer cell lines (OVCAR8, SKOV3, and NAR). Our findings show that an IP injection of ErbB2CAR-T cells to tumor-bearing mice led to disease remission and increased survival compared to the IV route. Moreover, we found that IP-injected ErbB2CART cells circulate to a lesser extent, making them safer for non-tumor tissues than IV-injected cells. Further supporting our findings, we show that the effect of ErbB2CAR-T cells on primary HGSOC tumors is correlated with ErbB2 expression. Together, these data demonstrate the advantages of an IP administration of CAR-T cells over IV administration, offering not only a safer strategy but also the potential for counteracting the effect of ErbB2CAR in HGSOC. Significance: IP-injected ErbB2CAR-T cells led to disease remission and increased survival compared to the IV route. These findings demonstrate the advantages of IP administration, offering a safe treatment strategy with the potential for counteracting the effect of ErbB2CAR in HGSOC.

Extracellular Vesicles Derived from Chimeric Antigen Receptor-T Cells: A Potential Therapy for Cancer

Chimeric antigen receptor (CAR)-T cells are genetically engineered T cells, directed against a tumor-associated antigen. Extracellular vesicles (EVs) derived from CAR-T cells (CAR-T EVs) may preserve CAR-T activity and overcome one of the major obstacles responsible for CAR-T cell failure in patients with solid tumors. This study aimed to compare CAR-T EVs with their parental cells and explore their cell penetration and cytotoxic activity. Anti-HER-2 CARs were stimulated with specific target cells. EVs were isolated from the cell media and characterized for their content and functions. We found that CAR-T EVs contained a mixture of small and large EVs. Stimulated anti-HER-2⁺ CAR-T EVs expressed lower cytokine levels compared with their parental CAR-T cells (such as interferon gamma). Higher levels of granzyme B were found in CAR-T EVs (≥20 × ) compared with EVs from unstimulated cells (p < 0.001). Anti-HER-2⁺ CAR-T EVs bound and penetrated specifically into HER-2 expressing target cells. Similar cytotoxic effects measured by caspase-3/7 activity were found in CAR-T cells and their derived EVs. However, while the CAR-T cells induced massive apoptosis during the first 24 h, CAR-T EVs required 60 - 90 h. In summary, CAR-T EVs provide a novel potent immunotherapy approach that may be effective against solid tumors.

CAR T cells: Building on the CD19 paradigm

Spearheaded by the therapeutic use of chimeric antigen receptors (CARs) targeting CD19, synthetic immunology has entered the clinical arena. CARs are recombinant receptors for antigen that engage cell surface molecules through the variable region of an antibody and signal through arrayed T-cell activating and costimulatory domains. CARs allow redirection of T-cell cytotoxicity against any antigen of choice, independent of MHC expression. Patient T cells engineered to express CARs specific for CD19 have yielded remarkable outcomes in subjects with relapsed/refractory B- cell malignancies, setting off unprecedented interest in T-cell engineering and cell-based cancer immunotherapy. In this review, we present the challenges to extend the use of CAR T cells to solid tumors and other pathologies. We further highlight progress in CAR design, cell manufacturing, and genome editing, which in aggregate hold the promise of generating safer and more effective genetically instructed immunity. Novel engineered cell types, including innate T-cell types, natural killer (NK) cells, macrophages, and induced pluripotent stem cell-derived immune cells, are on the horizon, as are applications of CAR T cells to treat autoimmunity, severe infections, and senescence-associated pathologies.

P32-specific CAR T cells with dual antitumor and antiangiogenic therapeutic potential in gliomas

Glioblastoma is considered one of the most aggressive malignancies in adult and pediatric patients. Despite decades of research no curative treatment is available and it thus remains associated with a very dismal prognosis. Although recent pre-clinical and clinical studies have demonstrated the feasibility of chimeric antigen receptors (CAR) T cell immunotherapeutic approach in glioblastoma, tumor heterogeneity and antigen loss remain among one of the most important challenges to be addressed. In this study, we identify p32/gC1qR/HABP/C1qBP to be specifically expressed on the surface of glioma cells, making it a suitable tumor associated antigen for redirected CAR T cell therapy. We generate p32 CAR T cells and find them to recognize and specifically eliminate p32 expressing glioma cells and tumor derived endothelial cells in vitro and to control tumor growth in orthotopic syngeneic and xenograft mouse models. Thus, p32 CAR T cells may serve as a therapeutic option for glioblastoma patients.

Chimeric antigen receptor (CAR) T cell therapy has been proposed as a promising approach for treating glioblastoma. Here the authors show that p32 is expressed in murine and human glioma and that p32-directed CAR-T cells promote anti-tumor responses in preclinical models by targeting glioma cells and tumor derived endothelial cells.

Proteolysis Targeting Chimeras for BTK Efficiently Inhibit B-Cell Receptor Signaling and Can Overcome Ibrutinib Resistance in CLL Cells

Proteolysis targeting chimeras (PROTACs) are small molecules that form ternary complexes between their target and E3 ligase, resulting in ubiquitination and proteasomal degradation of the target protein. Using our own designed Bruton's tyrosine kinase (BTK) PROTAC compounds, we show herein efficient BTK degradation in chronic lymphocytic leukemia (CLL) cells. The reversible non-covalent compound (NC-1) was the most potent and therefore we focused on this PROTAC to investigate its subsequent effects on the BCR pathway. NC-1 decreased baseline BTK phosphorylation as well as activation of BTK and other signaling molecules downstream of the BCR pathway, following IgM engagement. These effects were also obtained in samples from CLL patients with clinical resistance to ibrutinib and mutations at C481. NC-1 treatment further decreased baseline CD69 surface levels, completely abrogated its upregulation following IgM activation, decreased CLL cells migration toward SDF-1 and overcame stromal anti-apoptotic protection. In conclusion, our results indicate that targeting BTK using the PROTAC strategy could be a potential novel therapeutic approach for CLL.

Shaping Functional Avidity of CAR T Cells: Affinity, Avidity, and Antigen Density That Regulate Response

Chimeric antigen receptors (CARs) are immunoreceptors that redirect T cells to selectively kill tumor cells. Given their clinical successes in hematologic malignancies, there is a strong aspiration to advance this immunotherapy for solid cancers; hence, molecular CAR design and careful target choice are crucial for their function. To evaluate the functional significance of the biophysical properties of CAR binding (i.e., affinity, avidity, and antigen density), we generated an experimental system in which these properties are controllable. We constructed and characterized a series of CARs, which target the melanoma tumor-associated antigen Tyr/HLA-A2, and in which the affinity of the single-chain Fv binding domains ranged in K_D from 4 to 400 nmol/L. These CARs were transduced into T cells, and each CAR T-cell population was sorted by the level of receptor expression. Finally, the various CAR T cells were encountered with target cells that present different levels of the target antigen. We detected nonmonotonic behaviors of affinity and antigen density, and an interrelation between avidity and antigen density. Antitumor activity measurements in vitro and in vivo corroborated these observations. Our study contributes to the understanding of CAR T-cell function and regulation, having the potential to improve therapies by the rational design of CAR T cells.See related article on p. 946.

Treatment of Multiple Myeloma Using Chimeric Antigen Receptor T Cells with Dual Specificity

Chimeric antigen receptor (CAR) T-cell therapy has shown remarkable successes in fighting B-cell leukemias/lymphomas. Promising response rates are reported in patients treated with B-cell maturation antigen (BCMA) CAR T cells for multiple myeloma. However, responses appear to be nondurable, highlighting the need to expand the repertoire of multiple myeloma-specific targets for immunotherapy and to generate new CAR T cells. Here, we developed a "dual-CAR" targeting two multiple myeloma-associated antigens and explored its safety and efficacy. To reduce the "off-target" toxicity, we used the recognition of paired antigens that were coexpressed by the tumor to induce efficient CAR T-cell activation. The dual-CAR construct presented here was carefully designed to target the multiple myeloma-associated antigens, taking into consideration the distribution of both antigens on normal human tissues. Our results showed that the CD138/CD38-targeted dual CAR (dCAR138-38) elicited a potent anti-multiple myeloma response both in vitro and in vivo NSG mice transplanted with a multiple myeloma cell line and treated with dCAR138-38 showed median survival of 97 days compared with 31 days in the control group treated with mock-lymphocytes. The dCAR138-38 showed increased specificity toward cells expressing both targeted antigens compared with single-antigen-expressing cells and low activity toward primary cells from healthy tissues. Our findings indicated that the dCAR138-38 may provide a potent and safe alternative therapy for patients with multiple myeloma.

HER2-Targeted Polyinosine/Polycytosine Therapy Inhibits Tumor Growth and Modulates the Tumor Immune Microenvironment

The development of targeted therapies that affect multiple signaling pathways and stimulate antitumor immunity is greatly needed. About 20% of patients with breast cancer overexpress HER2. Small molecules and antibodies targeting HER2 convey some survival benefits; however, patients with advanced disease succumb to the disease under these treatment regimens, possibly because HER2 is not completely necessary for the survival of the targeted cancer cells. In the present study, we show that a polyinosine/polycytosine (pIC) HER2-homing chemical vector induced the demise of HER2-overexpressing breast cancer cells, including trastuzumab-resistant cells. Targeting pIC to the tumor evoked a number of cell-killing mechanisms, as well as strong bystander effects. These bystander mechanisms included type I IFN induction, immune cell recruitment, and activation. The HER2-targeted pIC strongly inhibited the growth of HER2-overexpressing tumors in immunocompetent mice. The data presented here could open additional avenues in the treatment of HER2-positive breast cancer. Cancer Immunol Res; 4(8); 688-97. ©2016 AACR.

The prevalence of antibodies to human T-lymphotropic virus type I in different population groups in Papua New Guinea

Isolation and partial sequencing of human T-lymphotropic virus type I (HTLV-I) variants from inhabitants of Papua New Guinea (PNG) and the Solomon Islands has confirmed the existence of virus infection in Melanesian populations. To determine the geographical distribution of seropositivity to HTLV-I in PNG we have tested 2907 serum and plasma samples collected between 1972 to 1991 from 16 different population groups. Samples were screened using a particle agglutination assay and confirmed by p21e-enhanced Western immunoblot (WB). From a total of 94 screen positive samples run on WB, 56 (60%) were confirmed positive (positive for both env and gag products) and 38 (40%) were WB-indeterminate (gag products only). The prevalence of WB-confirmed antibodies to HTLV-I in lowland and island populations ranged from 0 to 5.4%. There were no confirmed antibody positives in the highland populations surveyed. Geographically isolated populations living on the fringes of the highlands ranged in seropositivity from 0.2 to 5.8%. Two of the subjects surveyed gave WB antibody patterns characteristic of HTLV-II rather than HTLV-I infection.

Lymphocyte enzyme activities in East African blacks: decrease in 5'nucleotidase and possible relation to immunosuppression

Microanalysis of subcellular organelle marker enzymes was applied to cryopreserved lymphocytes (obtained and processed in the field) from East African blacks with moderate to severe malnutrition and subject to locally endemic parasitic and infectious diseases. An initial study demonstrated that activities of these enzymes, with the partial exception of catalase, were stable to cryopreservation. Cryopreserved and thawed lymphocyte specimens (1 to 3 X 10(6) viable cells) from 26 Africans and 20 Caucasian controls were studied. There was a highly significant decrease in 5'nucleotidase activity in these African subjects. Activity of another plasma membrane enzyme, gamma-glutamyl transferase, and of marker enzymes for other intracellular organelles, was not significantly different between the two groups, indicating that the nucleotidase alteration is highly specific. 5'Nucleotidase activity in a group of 17 East African blacks of high socio-economic status lay between the values obtained in the other two groups and was not significantly different from either. Further studies on 5'nucleotidase showed no evidence that the enzyme is functionally different in Africans. The differences in activity of this enzyme in Africans may reflect the known immuno-suppressive effects of infectious disease and malnutrition or may have a genetic basis which may in turn be associated with the pathogenesis of secondary immunodeficiency.

HLA antigens in East African Black patients with Burkitt's lymphoma or nasopharyngeal carcinoma and in controls: a pilot study

A pilot study is reported of HLA-A, B, and C antigens in 141 East African Blacks comprising patients with Burkitt's lymphoma or nasopharyngeal carcinoma, either with active disease or in long-term remission, together with comparable controls. This study forms part of a wider program investigating host factors in these diseases. A protocol was selected for optimal testing of cells processed and cryopreserved between 1972 and 1976, largely under field conditions, which employed a two-color fluorochromasia typing procedure. Antigen distribution and computed haplotype frequencies in the total unrelated population are given. New findings include an approximately equal frequency of Aw23 and Aw24, a high (18%) incidence of Bw21, and the gametic associations of Aw36 with Bw44, and Aw30 with Bw45. Of the major group of B15-related antigens reported earlier. SV is the most common, and there are strong linkages of SV with Cw2 and Bu with Cw3. The possible presence of further variants at the A- and B-loci is reported. The proportion of B-locus antigen "blanks" in this study is 5.9%. Relationships have been sought between the HLA antigens and diseases studied: the antigen A29, possibly in linkage with Bw42, shows a correlation with disease susceptibility, and associations are suggested between Bw44 (in possible combination with Aw36) and resistance to both BL and NPC, and between Bw45 and long-term remission in NPC.

B15 heterogeneity in East African Blacks

One-hundred-forty-one Blacks (135 unrelated) from Kenya and Tanzania have been tissue-typed (HLA-A, B and C loci) as part of a study of host factors involved in Burkitt's lymphoma and naso-pharyngeal carcinoma. Evidence is presented for the existence in this population of several B15-related antigens which together occur with a relatively high frequency of 30% in unrelated individuals. It is likely that these variants may include the antigens SV and perhaps Bu recently defined with population frequencies of under 1% in Caucasians. In the absence of monospecific typing sera, identification of these variants may be helped by their apparently strong association with C-locus antigens in Blacks. Recognition of these B15 variants has been largely responsible for reducing the proportion of unidentified or "blank" B-locus antigens in this population to only 6%. These findings substantiate and amplify previous reports suspecting the presence of such antigens in Blacks, and should facilitate studies of possible associations of disease with HLA in these populations.

Multiple cases of Burkitt's lymphoma and other neoplasms in families in the North Mara District of Tanzania

In an area of Tanzania in which Burkitt's lymphoma (BL) is endemic, five families are described in which multiple cases of BL were found or BL occurred with other neoplasms. The patients include two brothers and one half-brother with BL, two brothers with BL, a woman with nasopharyngeal carcinoma (NPC) whose daughter had BL, a boy with BL whose sister developed chronic myelogenous leukaemia (CML), and a man with CML whose son developed BL. The two full-sib pairs with BL is significantly more than would be expected to have arisen by chance and the association of BL with NPC and CML among close relatives is remarkable in view of the rarity of the last two neoplasms in the study area. It is suggested that genetic factors may be important. It is suggested that genetic factors may be important in determining susceptibility to the three malignancies in this population, but the possibility that the clustering of cases within families may be due to local environmental factors cannot be excluded.

In vitro immunological studies on East African cancer patients. II. Increased sensitivity of blood lymphocytes from untreated Burkitt lymphoma patients to inhibition of spontaneous rosette formation

Frozen aliquots of peripheral blood mononuclear cells from patients with Burkitt's lymphoma (BL) at various stages of the disease have been compared with samples from East African children who were healthy or who suffered from non-malinant disorders. Using the sheep-cell rosette test (which is believed to identify T-lymphocytes), we found a significant reduction in the proportion of rosette-forming cells (RFC) in the samples from untreated BL patients. After reduction of remission the difference between BL patients and controls was abolished. Rosette formation was more readily inhibited by anti-lymphocyte globulin (ALG) in samples from untreated BL patients than in controls. On induction of remission the rosette inhibition curve shifted towards the control values. The findings are compatible with the presence, in untreated BL, of a circulating factor which impairs the capacity of T-lymphocytes to form rosettes with sheep erythrocytes. It remains to be established whether the functional capacity of T-cells to protect the host against tumour proliferation is also impaired.

In vitro immunological studies on east african cancer patients. III. Spontaneous rosette formation by cells from Burkitt lymphoma biopsies

Spontaneous rosette formation was observed in eight out of nine Burkitt lymphoma biopsies. These were examined fresh and/or after culture in vitro for up to 48 h. The percentage of rosettes varied from 3.7% to 38%. There was a tendency for the percentage of rosettes to increase with time in tissue culture. It is suggested that the rosette-forming cells are T-lymphocytes infiltrating the tumour and functioning as a host defence mechanism against the proliferating tumour cells.

Hepatitis B antigen, antigen subtypes, and hepatitis B antibody in normal subjects and patients with liver disease

The relative sensitivities of counterimmunoelectrophoresis (CIE) and haemagglutination assays for the detection of hepatitis B surface antigen (HB(s)Ag) and antibodies (anti-HB(s)) were compared. Twelve scientists from ten countries in Asia, Africa and the Pacific region participated in the study. The participants provided serum samples from 15 953 subjects comprising patients with acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC), as well as blood donors and other normal individuals. For the detection of HB(s)Ag in a reference panel serum, immune adherence haemagglutination (IAHA) was slightly more sensitive than passive haemagglutination inhibition (PHI); CIE was the least sensitive. Mean HB(s)Ag frequencies in patients with acute hepatitis, chronic hepatitis, cirrhosis, and HCC were significantly higher than in healthy controls. Passive haemagglutination (PHA) was more sensitive than CIE for the detection of anti-HB(s). The frequency of anti-HB(s) in patients with HCC was significantly lower than that in the other groups. Mean anti-HB(s) frequencies in patients with acute hepatitis, chronic hepatitis, and cirrhosis were not significantly different from that in normal subjects. Subtyping of HB(s)Ag was performed by PHI. Among asymptomatic carriers the predominant HB(s)Ag subtype in northeast Asia was adr.In India, ayw predominated in carriers, with the demarcation between adr and ayw occurring west of Burma. In West Africa the only subtype detected was ayw, but in East Africa the majority subtype was adw. The r subtype was found only in Asian populations east of India and in Western Pacific populations. In Papua New Guinea all four subtypes were identified. With one possible exception, the subtypes of HB(s)Ag-positive patients with liver disease reflected the predominant type in each geographic location.

Production of 19S and 7S antibodies by cancer patients

The production of 7S and 19S antibody was compared in twenty-one patients with various types of carcinoma, four with lymphomatous neoplasms, and eleven healthy controls, at weekly intervals following administration of 17D yellow fever live virus vaccine. Sera were also tested for interferon and infectious virus. Mean and range of antibody titres were very similar in carcinoma patients and controls. There was a slight delay in antibody production in the cancer patients. Viraemia was demonstrated in 1/8 healthy controls, 4/20 carcinoma patients, and 2/3 lymphoma patients. No interferon was detected.