Phase I clinical trial combining imatinib mesylate and IL-2: HLA-DR+ NK cell levels correlate with disease outcome

Phase I/II Study of the Aurora Kinase A Inhibitor Alisertib and Pembrolizumab in Refractory, Rb-Deficient Head and Neck Squamous Cell Carcinomas

PURPOSE

Effective therapy for recurrent head and neck squamous cell carcinoma (HNSCC) that is refractory to chemotherapy and immunotherapy is a considerable need. Aurora kinase A inhibition leads to apoptosis and immunogenic cell death in preclinical models of human papilloma virus (HPV)-driven cancers.

PATIENTS AND METHODS

Alisertib was administered orally twice daily on days 1-7 and pembrolizumab on day 1 of a 21-day cycle to adults with advanced solid tumors (phase I) or with immunotherapy- and platinum-resistant, HPV-positive HNSCC (phase II).

RESULTS

The recommended phase II alisertib dose was 40 mg, which had only the expected toxicity including cytopenia that led to dose reductions in two phase II patients at cycles 13 and 16. We saw no objective responses, but the combination led to prolonged stable disease (SD) in several patients, including two of 10 phase I patients (8 and 27 months). Eight of the 15 HPV-positive patients had SD, of which four (heavily pretreated) had ≥6 months, with median overall and progression-free survival durations of 16.8 and 1.4 months, respectively. In circulating immune cells and plasma, patients with SD had markedly higher levels of HLA de novo resistance-expressing NK cells than did progressive disease patients who demonstrated a more immunosuppressive and inflammatory profile. Pharmacokinetics did not indicate any significant drug-drug interactions between pembrolizumab and alisertib.

CONCLUSIONS

The combination of alisertib and pembrolizumab was well tolerated and led to prolonged SD in some immunotherapy-resistant patients, supporting our hypothesis that Aurora kinase A inhibition can reverse immunotherapy resistance of retinoblastoma protein-deficient HNSCC.

Advances in immunology and immunotherapy for mesenchymal gastrointestinal cancers

Mesenchymal gastrointestinal cancers are represented by the gastrointestinal stromal tumors (GISTs) which occur throughout the whole gastrointestinal tract, and affect human health and economy globally. Curative surgical resections and tyrosine kinase inhibitors (TKIs) are the main managements for localized GISTs and recurrent/metastatic GISTs, respectively. Despite multi-lines of TKIs treatments prolonged the survival time of recurrent/metastatic GISTs by delaying the relapse and metastasis of the tumor, drug resistance developed quickly and inevitably, and became the huge obstacle for stopping disease progression. Immunotherapy, which is typically represented by immune checkpoint inhibitors (ICIs), has achieved great success in several solid tumors by reactivating the host immune system, and been proposed as an alternative choice for GIST treatment. Substantial efforts have been devoted to the research of immunology and immunotherapy for GIST, and great achievements have been made. Generally, the intratumoral immune cell level and the immune-related gene expressions are influenced by metastasis status, anatomical locations, driver gene mutations of the tumor, and modulated by imatinib therapy. Systemic inflammatory biomarkers are regarded as prognostic indicators of GIST and closely associated with its clinicopathological features. The efficacy of immunotherapy strategies for GIST has been widely explored in pre-clinical cell and mouse models and clinical experiments in human, and some patients did benefit from ICIs. This review comprehensively summarizes the up-to-date advancements of immunology, immunotherapy and research models for GIST, and provides new insights and perspectives for future studies.

The Polarity and Specificity of Antiviral T Lymphocyte Responses Determine Susceptibility to SARS-CoV-2 Infection in Patients with Cancer and Healthy Individuals

Vaccination against coronavirus disease 2019 (COVID-19) relies on the in-depth understanding of protective immune responses to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We characterized the polarity and specificity of memory T cells directed against SARS-CoV-2 viral lysates and peptides to determine correlates with spontaneous, virus-elicited, or vaccine-induced protection against COVID-19 in disease-free and cancer-bearing individuals. A disbalance between type 1 and 2 cytokine release was associated with high susceptibility to COVID-19. Individuals susceptible to infection exhibited a specific deficit in the T helper 1/T cytotoxic 1 (Th1/Tc1) peptide repertoire affecting the receptor binding domain of the spike protein (S1-RBD), a hotspot of viral mutations. Current vaccines triggered Th1/Tc1 responses in only a fraction of all subject categories, more effectively against the original sequence of S1-RBD than that from viral variants. We speculate that the next generation of vaccines should elicit Th1/Tc1 T-cell responses against the S1-RBD domain of emerging viral variants.

SIGNIFICANCE

This study prospectively analyzed virus-specific T-cell correlates of protection against COVID-19 in healthy and cancer-bearing individuals. A disbalance between Th1/Th2 recall responses conferred susceptibility to COVID-19 in both populations, coinciding with selective defects in Th1 recognition of the receptor binding domain of spike. See related commentary by McGary and Vardhana, p. 892. This article is highlighted in the In This Issue feature, p. 873.

HLA-DR-expressing NK cells: Effective killers suspected for antigen presentation

HLA-DR-expressing cells comprise an intriguing group of NK cells, which combine phenotypic characteristics of both NK cells and dendritic cells. These cells can be found in humans and mice; they are present in blood and tissues in healthy conditions and can expand in a spectrum of pathologies. HLA-DR⁺ NK cells are functionally active: they produce proinflammatory cytokines, degranulate, and easily proliferate in response to stimuli. Additionally, HLA-DR⁺ NK cells seem able to take in and then present certain antigens to CD4⁺ and CD8⁺ T cells, inducing their activation and proliferation, which puts them closer to professional antigen-presenting cells. It appears that these NK cells should be considerable players of the innate immune system, both due to their functional activity and regulation of the innate and adaptive immune responses. In this review, for the first time, we provide a detailed description and analysis of the available data characterizing phenotypic, developmental, and functional features of the HLA-DR⁺ NK cells in a healthy condition and a disease.

Imatinib modulates pro-inflammatory microenvironment with angiostatic effects in experimental lung carcinogenesis

Lung cancer has second highest rate of incidence and mortality around the world. Smoking cigarettes is the main stream cause of lung carcinogenesis along with other factors such as spontaneous mutations, inactivation of tumor suppressor genes. The present study was aimed to identify the mechanistic role of Imatinib in the chemoprevention of experimental lung carcinogenesis in rat model. Gross morphological observations for tumor formation, histological examinations, RT-PCR, Western blotting, fluorescence spectroscopy and molecular docking studies were performed to elucidate the chemopreventive effects of Imatinib and support our hypothesis by various experiments. It is evident that immuno-compromised microenvironment inside solid tumors is responsible for tumor progression and drug resistance. Therefore, it is inevitable to modulate the pro-inflammatory signaling inside solid tumors to restrict neoangiogenesis. In the present study, we observed that Imatinib could downregulate the inflammatory signaling and also attributed angiostatic effects. Moreover, Imatinib also altered the biophysical properties of BAL cells such as plasma membrane potential, fluidity and microviscosity to restrict their infiltration and thereby accumulation to mount immuno-compromised environment inside the solid tumors during angiogenesis. Our molecular docking studies suggest that immunomodulatory and angiostatic properties of Imatinib could be either independent of each other or just a case of synergistic pleiotropy. Imatinib was observed to activate the intrinsic or mitochondrial pathway of apoptosis to achieve desired effects in cancer cell killings. Interestingly, binding of Imatinib inside the catalytic domain of PARP-1 also suggests that it has caspase-independent properties in promoting cancer cell deaths.

Glycolipid Stimulation of Invariant NKT Cells Expands a Unique Tissue-Resident Population of Precursors to Mature NK Cells Endowed with Oncolytic and Antimetastatic Properties

Invariant NKT (iNKT) cells are innate-like T lymphocytes that recognize and respond to glycolipid Ags such as α-galactosylceramide (α-GalCer). This unique property has been exploited in clinical trials for multiple malignancies. While investigating mouse iNKT cell responses to α-GalCer in vivo, we found a dramatically enlarged tissue-resident population surprisingly coexpressing select dendritic cell, NK cell, and B cell markers. Further phenotypic and functional analyses revealed the identity of this B220⁺CD11c⁺MHC class II⁺NK1.1⁺ population as precursors to mature NK (pre-mNK) cells, which also expressed high levels of proliferation and tissue retention markers but diminished sphingosine-1-phosphate receptor 1, a receptor that facilitates tissue trafficking. Accordingly, FTY720, a sphingosine-1-phosphate receptor 1 antagonist, failed to prevent pre-mNK cells' intrahepatic accumulation. We found iNKT cell-driven expansion of pre-mNK cells to be dependent on IL-12 and IL-18. Although α-GalCer-transactivated pre-mNK cells lost their capacity to process a model tumor Ag, they selectively expressed granzyme A and directly lysed YAC-1 thymoma cells through granule exocytosis. They also contributed to β2 microglobulin-deficient target cell destruction in vivo. Therefore, α-GalCer treatment skewed pre-mNK cell responses away from an APC-like phenotype and toward killer cell-like functions. Finally, the ability of α-GalCer to reduce the pulmonary metastatic burden of B16-F10 mouse melanoma was partially reversed by in vivo depletion of pre-mNK cells. To our knowledge, our findings shed new light on iNKT cells' mechanism of action and glycolipid-based immunotherapies. Therefore, we introduce pre-mNK cells as a novel downstream effector cell type whose anticancer properties may have been overlooked in previous investigations.

Cyclophosphamide, Fluorouracil and subcutaneous Interleukin-2 in the treatment of advanced GIST: A Case Report

A male 68 years hold patient was admitted to surgical ward for hemorrhagic shock. After CT scan detection of 6x5 cm neoformation of first jejunal loop, he was submitted to segmental resection and pathological diagnosis was gastrointestinal stromal tumor. The patient was defined as high-risk according to Takahashi criteria, but refused Imatinib adjuvant therapy. After 15 months of disease-free interval, he developed bilobar liver metastases. After treatment with Imatinib 400 mg he reported G3 hepatotoxicity resolved with temporary suspension, he continue low dose with stable disease. After liver progression, he resumed Imatinib full dose with disease stabilization for 9 months. After liver progression, second line Sunitinib 37,5 mg/day was started for four months with stable disease. After further liver and lymph node mediastinal progression he was treated for four months with Regorafenib with disease stabilization. Patient developed slow but inexorable progression of liver disease with severe abdominal pain resistant to opioid and was treated with authorized compassionate program comprising Cyclophosphamide 300 mg/sqm and Fluorouracil 500 mg/sqm on day 1 intravenously followed by Interleukin-2 4.5 MUI subcutaneously on days 3–6 and 17–20 every four weeks. After three cycles the patients obtained a relevant subjective improvement with partial response on mediastinal lymph node and liver stabilization. A substantial increase on neutrophil, lymphocytes, monocytes, platelets, T regulator cells count, and a decrease on platelets/lymphocytes, CD8/T regulator cells ratio, CD8, NK count and C-reactive protein value were observed after treatment compared to basal value. The toxicity was mild represented by fever G1, flue-like-syndrome G1 during the treatment. After four cycle of chemo-immunotherapy, the patient demonstrated progression of disease and died five months after treatment. Noteworthy is the temporal disease control with significant symptomatic improvement achieved for the first time with this chemo-immunotherapeutic combination in a patient with very advanced pretreated GIST.

Porcine NK Cells Stimulate Proliferation of Pseudorabies Virus-Experienced CD8+ and CD4+CD8+ T Cells

Natural killer (NK) cells belong to the innate immune system and play a central role in the defense against viral infections and cancer development, but also contribute to shaping adaptive immune responses. NK cells are particularly important in the first line defense against herpesviruses, including alphaherpesviruses. In addition to their ability to kill target cells and produce interferon-γ, porcine and human NK cell subsets have been reported to display features associated with professional antigen presenting cells (APC), although it is currently unclear whether NK cells may internalize debris of virus-infected cells and whether this APC-like activity of NK cells may stimulate proliferation of antiviral T cells. Here, using the porcine alphaherpesvirus pseudorabies virus (PRV), we show that vaccination of pigs with a live attenuated PRV vaccine strain triggers expression of MHC class II on porcine NK cells, that porcine NK cells can internalize debris from PRV-infected target cells, and that NK cells can stimulate proliferation of CD8⁺ and CD4⁺CD8⁺ PRV-experienced T cells. These results highlight the potential of targeting these NK cell features in future vaccination strategies.

Analysis of NK cell clones obtained using interleukin-2 and gene-modified K562 cells revealed the ability of "senescent" NK cells to lose CD57 expression and start expressing NKG2A

In this work, we analyzed the phenotype and growth of human NK cell clones obtained by the stimulation of individual NK cells with IL-2 and gene-modified K562 feeder cells expressing membrane-bound IL-21 (K562-mbIL21). We generated clones from NK cells at distinct differentiation and activation stages, determined by CD56, CD57 and HLA-DR expression levels. Less differentiated CD56^bright NK cell subsets showed higher cloning efficiency compared with more differentiated CD56^dim subsets, especially with the CD57^bright subset. However, clones from the CD56^dimCD57^– subset lived longer on average than other subsets. Moreover, several clones with the highest cell numbers were derived from CD56^dimCD57^–HLA-DR⁻cells. Most of the clones including those derived from more differentiated CD56^dimCD57^+/–NKG2A^– NK cells showed a less-differentiated NKG2A⁺ phenotype. Also, CD57^– cells were frequently observed in clones derived from CD57⁺ NK cells suggesting the loss of CD57 during the cloning process. On the other hand, KIR surface expression once detected for a clone never disappeared entirely, confirming irreversibility of the KIR expression. In summary, we have demonstrated that in specific conditions terminally differentiated CD57⁺ human NK cells are able to acquire the CD57^– phenotype that was previously not observed and, thus, was considered impossible.

Baseline gut microbiota predicts clinical response and colitis in metastatic melanoma patients treated with ipilimumab

Background

Ipilimumab, an immune checkpoint inhibitor targeting CTLA-4, prolongs survival in a subset of patients with metastatic melanoma (MM) but can induce immune-related adverse events, including enterocolitis. We hypothesized that baseline gut microbiota could predict ipilimumab anti-tumor response and/or intestinal toxicity.

Patients and methods

Twenty-six patients with MM treated with ipilimumab were prospectively enrolled. Fecal microbiota composition was assessed using 16S rRNA gene sequencing at baseline and before each ipilimumab infusion. Patients were further clustered based on microbiota patterns. Peripheral blood lymphocytes immunophenotypes were studied in parallel.

Results

A distinct baseline gut microbiota composition was associated with both clinical response and colitis. Compared with patients whose baseline microbiota was driven by Bacteroides (cluster B, n = 10), patients whose baseline microbiota was enriched with Faecalibacterium genus and other Firmicutes (cluster A, n = 12) had longer progression-free survival (P = 0.0039) and overall survival (P = 0.051). Most of the baseline colitis-associated phylotypes were related to Firmicutes (e.g. relatives of Faecalibacterium prausnitzii and Gemmiger formicilis), whereas no colitis-related phylotypes were assigned to Bacteroidetes. A low proportion of peripheral blood regulatory T cells was associated with cluster A, long-term clinical benefit and colitis. Ipilimumab led to a higher inducible T-cell COStimulator induction on CD4+ T cells and to a higher increase in serum CD25 in patients who belonged to Faecalibacterium-driven cluster A.

Conclusion

Baseline gut microbiota enriched with Faecalibacterium and other Firmicutes is associated with beneficial clinical response to ipilimumab and more frequent occurrence of ipilimumab-induced colitis.

A2AR Adenosine Signaling Suppresses Natural Killer Cell Maturation in the Tumor Microenvironment

Extracellular adenosine is a key immunosuppressive metabolite that restricts activation of cytotoxic lymphocytes and impairs antitumor immune responses. Here, we show that engagement of A2A adenosine receptor (A2AR) acts as a checkpoint that limits the maturation of natural killer (NK) cells. Both global and NK-cell-specific conditional deletion of A2AR enhanced proportions of terminally mature NK cells at homeostasis, following reconstitution, and in the tumor microenvironment. Notably, A2AR-deficient, terminally mature NK cells retained proliferative capacity and exhibited heightened reconstitution in competitive transfer assays. Moreover, targeting A2AR specifically on NK cells also improved tumor control and delayed tumor initiation. Taken together, our results establish A2AR-mediated adenosine signaling as an intrinsic negative regulator of NK-cell maturation and antitumor immune responses. On the basis of these findings, we propose that administering A2AR antagonists concurrently with NK cell-based therapies may heighten therapeutic benefits by augmenting NK cell-mediated antitumor immunity.Significance: Ablating adenosine signaling is found to promote natural killer cell maturation and antitumor immunity and reduce tumor growth. Cancer Res; 78(4); 1003-16. ©2017 AACR.

Tumor immunoevasion by the conversion of effector NK cells into type 1 innate lymphoid cells

Avoiding destruction by immune cells is a hallmark of cancer, yet how tumors ultimately evade control by natural killer (NK) cells remains incompletely defined. Using global transcriptomic and flow-cytometry analyses and genetically engineered mouse models, we identified the cytokine-TGF-β-signaling-dependent conversion of NK cells (CD49a-CD49b+Eomes+) into intermediate type 1 innate lymphoid cell (intILC1) (CD49a+CD49b+Eomes+) populations and ILC1 (CD49a+CD49b-Eomesint) populations in the tumor microenvironment. Strikingly, intILC1s and ILC1s were unable to control local tumor growth and metastasis, whereas NK cells favored tumor immunosurveillance. Experiments with an antibody that neutralizes the cytokine TNF suggested that escape from the innate immune system was partially mediated by TNF-producing ILC1s. Our findings provide new insight into the plasticity of group 1 ILCs in the tumor microenvironment and suggest that the TGF-β-driven conversion of NK cells into ILC1s is a previously unknown mechanism by which tumors escape surveillance by the innate immune system.

Retroviral gene transfer into primary human NK cells activated by IL-2 and K562 feeder cells expressing membrane-bound IL-21

Natural killer (NK) cells are capable of rapidly recognizing and efficiently killing tumor cells. This makes them a potentially promising agent for cancer immunotherapy. Additional genetic modifications of NK cells may further improve their anti-tumor efficacy. Numerous technical challenges associated with gene delivery into NK cells have significantly tempered this approach. We achieved efficient retroviral vector transduction of primary human NK cells that were stimulated by a combination of IL-2 and engineered K562 cells expressing membrane-bound IL-21. The activated NK cells were in less differentiated state and expressed NK cell activation receptors NKG2D, NKp30, CD16, and were highly HLA-DR-positive. This NK cell population was highly susceptible to the transduction by both GFP- and NGFR-expressing retroviral vectors, with transduction efficiency exceeding 50%. More mature CD57⁺ NK cell population was generally resistant to retroviral vector transduction because of poor response to the stimulation. Our findings may facilitate retroviral vector-mediated genetic engineering of human primary NK cells for future immunotherapies.

A role for pre-mNK cells in tumor progression

The innate and adaptive immune systems have evolved together to fight infection and cancerous tissues. The innate immune system emerges first with the adaptive immune system following, both ostensibly being bridged by dendritic cells (DC). Recently cells have emerged that possess characteristics of both innate and adaptive immune cell qualities, termed interferon-producing killer dendritic cells (IKDCs). These cells have an indistinct origin that is not well understood. They appear to have more NK cell attributes than DC but purportedly can regulate the immune system similar to immunoregulatory NK cells. Because of this, they have been renamed pre-mNK cells (pre-mature NK cells). We argue in this commentary that pre-mNK cells may contribute to cancer recurrence.

PD-1 Blockade Expands Intratumoral Memory T Cells

Tumor responses to programmed cell death protein 1 (PD-1) blockade therapy are mediated by T cells, which we characterized in 102 tumor biopsies obtained from 53 patients treated with pembrolizumab, an antibody to PD-1. Biopsies were dissociated, and single-cell infiltrates were analyzed by multicolor flow cytometry using two computational approaches to resolve the leukocyte phenotypes at the single-cell level. There was a statistically significant increase in the frequency of T cells in patients who responded to therapy. The frequency of intratumoral B cells and monocytic myeloid-derived suppressor cells significantly increased in patients' biopsies taken on treatment. The percentage of cells with a regulatory T-cell phenotype, monocytes, and natural killer cells did not change while on PD-1 blockade therapy. CD8(+) memory T cells were the most prominent phenotype that expanded intratumorally on therapy. However, the frequency of CD4(+) effector memory T cells significantly decreased on treatment, whereas CD4(+) effector T cells significantly increased in nonresponding tumors on therapy. In peripheral blood, an unusual population of blood cells expressing CD56 was detected in two patients with regressing melanoma. In conclusion, PD-1 blockade increases the frequency of T cells, B cells, and myeloid-derived suppressor cells in tumors, with the CD8(+) effector memory T-cell subset being the major T-cell phenotype expanded in patients with a response to therapy.

PD-1 Blockade Expands Intratumoral Memory T Cells

Tumor responses to programmed cell death protein 1 (PD-1) blockade therapy are mediated by T cells, which we characterized in 102 tumor biopsies obtained from 53 patients treated with pembrolizumab, an antibody to PD-1. Biopsies were dissociated, and single-cell infiltrates were analyzed by multicolor flow cytometry using two computational approaches to resolve the leukocyte phenotypes at the single-cell level. There was a statistically significant increase in the frequency of T cells in patients who responded to therapy. The frequency of intratumoral B cells and monocytic myeloid-derived suppressor cells significantly increased in patients' biopsies taken on treatment. The percentage of cells with a regulatory T-cell phenotype, monocytes, and natural killer cells did not change while on PD-1 blockade therapy. CD8(+) memory T cells were the most prominent phenotype that expanded intratumorally on therapy. However, the frequency of CD4(+) effector memory T cells significantly decreased on treatment, whereas CD4(+) effector T cells significantly increased in nonresponding tumors on therapy. In peripheral blood, an unusual population of blood cells expressing CD56 was detected in two patients with regressing melanoma. In conclusion, PD-1 blockade increases the frequency of T cells, B cells, and myeloid-derived suppressor cells in tumors, with the CD8(+) effector memory T-cell subset being the major T-cell phenotype expanded in patients with a response to therapy.

Natural killer cell mediated immunosurveillance of pediatric neuroblastoma

Until recently, the pathophysiological impact of natural killer (NK) lymphocytes has been largely elusive. Capitalizing on our previous discovery that NK cells mediate immunosurveillance against gastrointestinal stromal tumors (GISTs), we have now investigated the potential influence of immunostimulatory and immunosuppressive isoforms of the NK receptor NKp30 on the fate of infants with neuroblastoma. In three independent cohorts of high-risk neuroblastoma, we observed a similar prognostic impact of the ratio of immunostimulatory vs. immunosuppressive NKp30 isoforms. Patients with high-risk neuroblastoma that are in remission after induction chemotherapy have a higher risk of relapse if their circulating and bone marrow NK cells express the preponderantly immunosuppressive NKp30 C isoform, as determined by a robust RT-PCR-based assay. We also found that neuroblastoma cells express the NKp30 ligand B7-H6, which can be shed from the tumor cells. Elevated soluble B7-H6 levels contained in patient sera inhibited NK functions in vitro and correlated with downregulation of NK-p30 on NK cells, as well as with bone marrow metastasis and chemoresistance. Altogether, these results support the contention that NK cells play a decisive role in the immunosurveillance of neuroblastoma. In light of these results, efforts should be undertaken to investigate NK cell functions in all major cancer types, with the obvious expectation of identifying additional NK cell-related prognostic or predictive biomarkers and improving NK cell based immunotherapeutic strategies against cancer.

Trial watch: Dendritic cell-based anticancer therapy

The use of patient-derived dendritic cells (DCs) as a means to elicit therapeutically relevant immune responses in cancer patients has been extensively investigated throughout the past decade. In this context, DCs are generally expanded, exposed to autologous tumor cell lysates or loaded with specific tumor-associated antigens (TAAs), and then reintroduced into patients, often in combination with one or more immunostimulatory agents. As an alternative, TAAs are targeted to DCs in vivo by means of monoclonal antibodies, carbohydrate moieties or viral vectors specific for DC receptors. All these approaches have been shown to (re)activate tumor-specific immune responses in mice, often mediating robust therapeutic effects. In 2010, the first DC-based preparation (sipuleucel-T, also known as Provenge®) has been approved by the US Food and Drug Administration (FDA) for use in humans. Reflecting the central position occupied by DCs in the regulation of immunological tolerance and adaptive immunity, the interest in harnessing them for the development of novel immunotherapeutic anticancer regimens remains high. Here, we summarize recent advances in the preclinical and clinical development of DC-based anticancer therapeutics.

c-Abl modulates tumor cell sensitivity to antibody-dependent cellular cytotoxicity

Monoclonal antibodies (mAb) can modulate cancer cell signal transduction and recruit antitumor immune effector mechanisms-including antibody-dependent cellular cytotoxicity (ADCC). Although several clinically effective antibodies can promote ADCC, therapeutic resistance is common. We hypothesized that oncogenic signaling networks within tumor cells affect their sensitivity to ADCC. We developed a screening platform and targeted 60 genes derived from an EGFR gene network using RNAi in an in vitro ADCC model system. Knockdown of GRB7, PRKCE, and ABL1 enhanced ADCC by primary and secondary screens. ABL1 knockdown also reduced cell proliferation, independent of its ADCC enhancement effects. c-Abl overexpression decreased ADCC sensitivity and rescued the effects of ABL1 knockdown. Imatinib inhibition of c-Abl kinase activity also enhanced ADCC-phenocopying ABL1 knockdown-against several EGFR-expressing head-and-neck squamous cell carcinoma cell lines by ex vivo primary natural killer cells. Our findings suggest that combining c-Abl inhibition with ADCC-promoting antibodies, such as cetuximab, could translate into increased therapeutic efficacy of mAbs.

A think tank of TINK/TANKs: tumor-infiltrating/tumor-associated natural killer cells in tumor progression and angiogenesis

Tumor-infiltrating leukocytes are often induced by the cancer microenvironment to display a protumor, proangiogenic phenotype. This “polarization” has been described for several myeloid cells, in particular macrophages. Natural killer (NK) cells represent another population of innate immune cells able to infiltrate tumors. The role of NK in tumor progression and angiogenesis has not yet been fully investigated. Several studies have shown that tumor-infiltrating NK (here referred to as “TINKs”) and tumor-associated NK (altered peripheral NK cells, which here we call “TANKs”) are compromised in their ability to lysew tumor cells. Recent data have suggested that they are potentially protumorigenic and can also acquire a proangiogenic phenotype. Here we review the properties of TINKs and TANKs and compare their activities to that of NK cells endowed with a physiological proangiogenic phenotype, in particular decidual NK cells. We speculate on the potential origins of TINKs and TANKs and on the immune signals involved in their differentiation and polarization. The TINK and TANK phenotype has broad implications in the immune response to tumors, ranging from a deficient control of cancer and cancer stem cells to an altered crosstalk with other relevant players of the immune response, such as dendritic cells, to induction of cancer angiogenesis. With this recently acquired knowledge that has not yet been put into perspective, we point out new potential avenues for therapeutic intervention involving NK cells as a target or an ally in oncology.

Dasatinib promotes Th1-type responses in granzyme B expressing T-cells

Tyrosine kinase inhibitors (TKIs) have dramatically improved the outcome of chronic myeloid leukemia (CML). Besides inhibiting target kinases in leukemic cells, 2nd generation TKI dasatinib also inhibits off-targets in immune effector cells resulting in atypical immune responses in some patients. Dasatinib has been described to increase the proportion of late effector memory T-cells, however, to date no follow-up studies have been performed in first-line patients. In this study, we explored the functional properties of T-cells using primary samples from CML patients (n = 28) on TKI therapy. Granzyme B (GrB) was used as a marker for late phase antigen experienced CD4+ and CD8+ T-cells. Dasatinib treatment increased the numbers of both GrB expressing memory CD4+ and CD8+ T-cells when compared with healthy controls. Functionally, the GrB+CD4+ T-cells were highly active and differentiated into Th1-type T-cells capable of producing IFN-γ, which is important for tumor control. Similar kind of increase was not observed during imatinib or nilotinib therapy. These data support the dual mode of action of dasatinib: potent BCR-ABL1 inhibition in leukemic cells is accompanied by the enhancement of cellular immunity, which may have implications in the long-term control of leukemia.

Trial Watch: Chemotherapy with immunogenic cell death inducers

Accumulating evidence suggests that the clinical efficacy of selected anticancer drugs, including conventional chemotherapeutics as well as targeted anticancer agents, originates (at least in part) from their ability to elicit a novel or reinstate a pre-existing tumor-specific immune response. One of the mechanisms whereby chemotherapy can stimulate the immune system to recognize and destroy malignant cells is commonly known as immunogenic cell death (ICD). Cancer cells succumbing to ICD are de facto converted into an anticancer vaccine and as such elicit an adaptive immune response. Several common chemotherapeutics share the ability of triggering ICD, as demonstrated in vaccination experiments relying on immunocompetent mice and syngeneic cancer cells. A large number of ongoing clinical trials involve such ICD inducers, often (but not always) as they are part of the gold standard therapeutic approach against specific neoplasms. In this Trial Watch, we summarize the latest advances on the use of cyclophosphamide, doxorubicin, epirubicin, oxaliplatin, and mitoxantrone in cancer patients, discussing high-impact studies that have been published during the last 13 months as well as clinical trials that have been initiated in the same period to assess the antineoplastic profile of these immunogenic drugs as off-label therapeutic interventions.

Revisiting the Prominent Anti-Tumoral Potential of Pre-mNK Cells

Interferon-producing killer dendritic cells (IKDC) were first described for their outstanding anti-tumoral properties. The “IKDC” terminology implied the description of a novel DC subset and initiated a debate on their cellular lineage origin. This debate shifted the focus away from their notable anti-tumoral potential. IKDC were recently redefined as precursors to mature NK (mNK) cells and consequently renamed pre-mNK cells. Importantly, a putative human equivalent of pre-mNK cells was recently associated with improved disease outcome in cancer patients. It is thus timely to revisit the functional attributes as well as the therapeutic potential of pre-mNK cells in line with their newly defined NK-cell precursor function.