Antitumor immunity induced by antibody-based natural killer cell engager therapeutics armed with not-alpha IL-2 variant.

Harnessing innate immunity is emerging as a promising therapeutic approach in cancer. We report here the design of tetraspecific molecules engaging natural killer (NK) cell-activating receptors NKp46 and CD16a, the ß-chain of the interleukin-2 receptor (IL-2R), and a tumor-associated antigen (TAA). In vitro, these tetraspecific antibody-based natural killer cell engager therapeutics (ANKETs) induce a preferential activation and proliferation of NK cells, and the binding to the targeted TAA triggers NK cell cytotoxicity and cytokine and chemokine production. In vivo, tetraspecific ANKETs induce NK cell proliferation and their accumulation at the tumor bed, as well as the control of local and disseminated tumors. Treatment of non-human primates with CD20-directed tetraspecific ANKET leads to CD20+ circulating B cell depletion, with minimal systemic cytokine release and no sign of toxicity. Tetraspecific ANKETs, thus, constitute a technological platform for harnessing NK cells as next-generation cancer immunotherapies.

Targeting MICA/B with cytotoxic therapeutic antibodies leads to tumor control.

Background: MICA and MICB are tightly regulated stress-induced proteins that trigger the immune system by binding to the activating receptor NKG2D on cytotoxic lymphocytes. MICA and MICB are highly polymorphic molecules with prevalent expression on several types of solid tumors and limited expression in normal/healthy tissues, making them attractive targets for therapeutic intervention. Methods: We have generated a series of anti-MICA and MICB cross-reactive antibodies with the unique feature of binding to the most prevalent isoforms of both these molecules. Results: The anti-MICA and MICB antibody MICAB1, a human IgG1 Fc-engineered monoclonal antibody (mAb), displayed potent antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of MICA/B-expressing tumor cells in vitro. However, it showed insufficient efficiency against solid tumors in vivo, which prompted the development of antibody-drug conjugates (ADC). Indeed, optimal tumor control was achieved with MICAB1-ADC format in several solid tumor models, including patient-derived xenografts (PDX) and carcinogen-induced tumors in immunocompetent MICAgen transgenic mice. Conclusions: These data indicate that MICA and MICB are promising targets for cytotoxic immunotherapy.

Tumor-Infiltrating Natural Killer Cells.

Because of their potent antitumor activity and their proinflammatory role, natural killer (NK) cells are at the forefront of efforts to develop immuno-oncologic treatments. NK cells participate in immune responses to tumors by killing target cells and producing cytokines. However, in the immunosuppressive tumor microenvironment, NK cells become dysfunctional through exposure to inhibitory molecules produced by cancer cells, leading to tumor escape. We provide an overview of what is known about NK tumor infiltration and surveillance and about the mechanisms by which NK cells become dysfunctional. SIGNIFICANCE: The functions of tumor-infiltrating NK cells may be impaired. This review aims to describe the various mechanisms by which tumors alter NK-cell functions.

Low Circulating Natural Killer Cell Counts are Associated With Severe Disease in Patients With Common Variable Immunodeficiency.

Natural Killer (NK) cells have been shown to exert antiviral and antitumoural activities. Nevertheless most available data are derived from mouse models and functions of these cells in human remain unclear. To evaluate the impact of low circulating NK cell counts and to provide some clues to the role of NK cells in natural conditions, we studied a large cohort of patients with common variable immunodeficiency (CVID) included in a multicenter cohort of patients with primary hypogammaglobulinaemia. Patients were classified into three groups on the basis of their NK cell counts: severe and mild NK cell lymphopenia (<50 and 50-99×10(6)/L respectively), and normal NK cell counts (>100×10(6)/L). Clinical events were analyzed and compared between these three groups of patients. During study period, 457 CVID patients were included: 99 (21.7%) with severe NK cell lymphopenia, 118 (25.8%) with mild NK cell lymphopenia and 240 (52.5%) with normal NK cell counts. Non-infectious complications (57% vs. 36% and 35%), and, particularly, granulomatous complications (25.3% vs. 13.6% and 8.8%), were more frequent in patients with severe NK cell lymphopenia than in other groups. Invasive infections (68.7% vs. 60.2% and 48.8%), including bacteraemia (22.2% vs. 5.9% and 8.3%) and infectious pneumonia (63.6% vs. 59.3% and 44.2%), were also more frequent in this population. However, no difference was observed for viral infections and neoplasms. Low circulating NK cell counts are associated with more severe phenotypes of CVID, which may indicate a protective role of these immune cells against severe bacterial infections and other complications and non-redundant immune functions when the adaptive immune response is not optimal.

Innate lymphoid cells: parallel checkpoints and coordinate interactions with T cells.

Protection of epithelial and mucosal surfaces is required for survival. The recent discovery of a diverse array of innate lymphoid cells that lie immediately beneath these surfaces has unexpectedly uncovered an entire defense system distinct from the adaptive system essential to protect these barriers. This multilayered design provides a robust system through coupling of two highly complementary networks to ensure immune protection. Here, we discuss the similarities in the hardwiring and diversification of innate lymphoid cells and T cells during mammalian immune responses.

Complementarity and redundancy of IL-22-producing innate lymphoid cells.

Intestinal T cells and group 3 innate lymphoid cells (ILC3 cells) control the composition of the microbiota and gut immune responses. Within the gut, ILC3 subsets coexist that either express or lack the natural cytoxicity receptor (NCR) NKp46. We identified here the transcriptional signature associated with the transcription factor T-bet-dependent differentiation of NCR(-) ILC3 cells into NCR(+) ILC3 cells. Contrary to the prevailing view, we found by conditional deletion of the key ILC3 genes Stat3, Il22, Tbx21 and Mcl1 that NCR(+) ILC3 cells were redundant for the control of mouse colonic infection with Citrobacter rodentium in the presence of T cells. However, NCR(+) ILC3 cells were essential for cecal homeostasis. Our data show that interplay between intestinal ILC3 cells and adaptive lymphocytes results in robust complementary failsafe mechanisms that ensure gut homeostasis.

A new sensitive PCR assay for one-step detection of 12 IDH1/2 mutations in glioma.

INTRODUCTION: Mutations in isocitrate dehydrogenase genes IDH1 or IDH2 are frequent in glioma, and IDH mutation status is a strong diagnostic and prognostic marker. Current IDH mutation screening is performed with an immunohistochemistry (IHC) assay specific for IDH1 R132H, the most common mutation. Sequencing is recommended as a second-step test for IHC-negative or -equivocal cases. We developed and validated a new real-time quantitative polymerase chain reaction (PCR) assay for single-step detection of IDH1 R132H and 11 rare IDH1/2 mutations in formalin-fixed paraffin-embedded (FFPE) glioma samples. Performance of the IDH1/2 PCR assay was compared to IHC and Sanger sequencing. RESULTS: The IDH1/2 PCR assay combines PCR clamping for detection of 7 IDH1 and 5 IDH2 mutations, and Amplification Refractory Mutation System technology for specific identification of the 3 most common mutations (IDH1 R132H, IDH1 R132C, IDH2 R172K). Analytical sensitivity of the PCR assay for mutation detection was <5% for 11/12 mutations (mean: 3.3%), and sensitivity for mutation identification was very high (0.8% for IDH1 R132H; 1.2% for IDH1 R132C; 0.6% for IDH2 R172K). Assay performance was further validated on 171 clinical glioma FFPE samples; of these, 147 samples met the selection criteria and 146 DNA samples were successfully extracted. IDH1/2 status was successfully obtained in 91% of cases. All but one positive IDH1 R132H-IHC cases were concordantly detected by PCR and 3 were not detected by sequencing. Among the IHC-negative cases (n = 72), PCR detected 12 additional rare mutations (10 IDH1, 2 IDH2). All mutations detected by sequencing (n = 67) were concordantly detected by PCR and 5/66 sequencing-negative cases were PCR-positive (overall concordance: 96%). Analysis of synthetic samples representative of the 11 rare IDH1/2 mutations detected by the assay produced 100% correct results. CONCLUSIONS: The new IDH1/2 PCR assay has a high technical success rate and is more sensitive than Sanger sequencing. Positive concordance was 98% with IHC for IDH1 R132H detection and 100% with sequencing. The PCR assay can reliably be performed on FFPE samples and has a faster turnaround time than current IDH mutation detection algorithms. The assay should facilitate implementation of a comprehensive IDH1/2 testing protocol in routine clinical practice.

Respective prognostic value of genomic grade and histological proliferation markers in early stage (pN0) breast carcinoma.

BACKGROUND: Genomic grade (GG) is a 97-gene signature which improves the accuracy and prognostic value of histological grade (HG) in invasive breast carcinoma. Since most of the genes included in the GG are involved in cell proliferation, we performed a retrospective study to compare the prognostic value of GG, Mitotic Index and Ki67 score. METHODS: A series of 163 consecutive breast cancers was retained (pT1-2, pN0, pM0, 10-yr follow-up). GG was computed using MapQuant Dx(R). RESULTS: GG was low (GG-1) in 48%, high (GG-3) in 31% and equivocal in 21% of cases. For HG-2 tumors, 50% were classified as GG-1, 18% as GG-3 whereas 31% remained equivocal. In a subgroup of 132 ER+/HER2- tumors GG was the most significant prognostic factor in multivariate Cox regression analysis adjusted for age and tumor size (HR = 5.23, p = 0.02). CONCLUSIONS: In a reference comprehensive cancer center setting, compared to histological grade, GG added significant information on cell proliferation in breast cancers. In patients with HG-2 carcinoma, applying the GG to guide the treatment scheme could lead to a reduction in adjuvant therapy prescription. However, based on the results observed and considering (i) the relatively close prognostic values of GG and Ki67, (ii) the reclassification of about 30% of HG-2 tumors as Equivocal GG and (iii) the economical and technical requirements of the MapQuant micro-array GG test, the availability in the near future of a PCR-based Genomic Grade test with improved performances may lead to an introduction in clinical routine of this test for histological grade 2, ER positive, HER2 negative breast carcinoma.

Beta-catenin status in paediatric medulloblastomas: correlation of immunohistochemical expression with mutational status, genetic profiles, and clinical characteristics.

Medulloblastoma is the most frequent malignant paediatric brain tumour. The activation of the Wnt/beta-catenin pathway occurs in 10-15% of medulloblastomas and has been recently described as a marker for favourable patient outcome. We report a series of 72 paediatric medulloblastomas evaluated for beta-catenin protein expression, CTNNB1 mutations, and comparative genomic hybridization. Gene expression profiles were also available in a subset of 40 cases. Immunostaining of beta-catenin showed extensive nuclear staining (>50% of the tumour cells) in six cases and focal nuclear staining (<10% of cells) in three cases. The other cases either exhibited a signal strictly limited to the cytoplasm (58 cases) or were negative (five cases). CTNNB1 mutations were detected in all beta-catenin extensively nucleopositive cases. The expression profiles of these cases documented strong activation of the Wnt/beta-catenin pathway. Remarkably, five out of these six tumours showed a complete loss of chromosome 6. In contrast, cases with focal nuclear beta-catenin staining, as well as tumours with negative or cytoplasmic staining, never demonstrated CTNNB1 mutation, Wnt/beta-catenin pathway activation or chromosome 6 loss. Patients with extensive nuclear staining were significantly older at diagnosis and were in continuous complete remission after a mean follow-up of 75.7 months (range 27.5-121.2 months) from diagnosis. All three patients with focal nuclear staining of beta-catenin died within 36 months from diagnosis. Altogether, these data confirm and extend previous observations that CTNNB1-mutated tumours represent a distinct molecular subgroup of medulloblastomas with favourable outcome, indicating that therapy de-escalation should be considered. International consensus on the definition criteria of this distinct medulloblastoma subgroup should be achieved.

APC inactivation associates with abnormal mitosis completion and concomitant BUB1B/MAD2L1 up-regulation.

BACKGROUND & AIMS: Chromosomal instability, a hallmark of most colorectal cancers, has been related to altered chromosome segregation and the consequent deficit in genetic integrity. A role for the tumor suppressor gene APC has been proposed in colorectal cancer that leads to compromised chromosome segregation even though the molecular mechanism is not yet understood. Here, we tackled the genetic basis for the contribution of APC to chromosomal instability in familial adenomatous polyposis and sporadic colorectal cancer. METHODS: We have used video-microscopy of primary cultures and molecular genetic methods to address these issues in human samples and in genetically defined mouse models that either recapitulate the familial adenomatous polyposis syndrome (Apc(1638N)), or develop tumors in the absence of APC mutations (pvillin-KRASV12G). RESULTS: Mutations in APC were associated with an increased incidence in cell cycle defects during the completion of cytokinesis. Transcriptome analysis performed on mouse models indicated a significant up-regulation of genes that regulate accurate mitosis. Notably, we identified up-regulated expression of BUB1B and MAD2L1, 2 genes that are involved in the mitotic checkpoint, but have so far not been implicated in chromosomal instability induced by APC loss of function. In vitro modulation of APC expression suggested a causal association for this upregulation, which was consistently found in sporadic and familial adenomatous polyposis lesions, as an early event in colorectal tumorigenesis. CONCLUSIONS: In addition to the known function of APC during correct spindle assembly and positioning, we propose a concomitant involvement of APC in the surveillance mechanism of accurate mitosis.