Intraperitoneal administration of a modified vaccinia virus Ankara confers single-chain interleukin-12 expression to the omentum and achieves immune-mediated efficacy against peritoneal carcinomatosis

BACKGROUND

Peritoneal carcinomatosis is an advanced stage of cancer in which the disease has spread to the peritoneal cavity. In order to restore antitumor immunity subverted by tumor cells in this location, we evaluated intraperitoneal administrations of modified vaccinia virus Ankara (MVA) engineered to express single-chain interleukin 12 (scIL-12) to increase antitumor immune responses.

METHODS

MVA encoding scIL-12 (MVA.scIL-12) was evaluated against peritoneal carcinomatosis models based on intraperitoneal engraftment of tumor cells. CD8-mediated immune responses, elucidated antitumor efficacy, and safety were evaluated following intravenous, intratumoral, or intraperitoneal administration of the viral vector. The immune response was measured by ELISpot (enzyme-linked immunosorbent spot), RNA sequencing, flow cytometry, intravital microscopy, and depletion of lymphocyte subsets with monoclonal antibodies. Safety was assessed by body-weight follow-up and blood testing. Tissue tropism on intravenous or intraperitoneal administration was assessed by bioluminescence analysis using a reporter MVA encoding luciferase.

RESULTS

Intraperitoneal or locoregional administration, but not other routes of administration, resulted in a potent immune response characterized by increased levels of tumor-specific CD8+ T lymphocytes with the ability to produce both interferon-γ and tumor necrosis factor-α. The antitumor immune response was detectable not only in the peritoneal cavity but also systemically. As a result of intraperitoneal treatment, a single administration of MVA.scIL-12 encoding scIL-12 completely eradicated MC38 tumors implanted in the peritoneal cavity and also protected cured mice from subsequent subcutaneous rechallenges. Bioluminescence imaging using an MVA encoding luciferase revealed that intraperitoneal administration targets transgene to the omentum. The omentum is considered a key tissue in immune protection of the peritoneal cavity. The safety profile of intraperitoneal administration was also better than that following intravenous administration since no weight loss or hematological toxicity was observed when the vector was locally delivered into the peritoneal cavity.

CONCLUSION

Intraperitoneal administration of MVA vectors encoding scIL-12 targets the omentum, which is the tissue where peritoneal carcinomatosis usually begins. MVA.scIL-12 induces a potent tumor-specific immune response that often leads to the eradication of experimental tumors disseminated to the peritoneal cavity.

Armored modified vaccinia Ankara in cancer immunotherapy

Cancer immunotherapy relies on unleashing the patient´s immune system against tumor cells. Cancer vaccines aim to stimulate both the innate and adaptive arms of immunity to achieve durable clinical responses. Some roadblocks for a successful cancer vaccine in the clinic include the tumor antigen of choice, the adjuvants employed to strengthen antitumor-specific immune responses, and the risks associated with enhancing immune-related adverse effects in patients. Modified vaccinia Ankara (MVA) belongs to the family of poxviruses and is a versatile vaccine platform that combines several attributes crucial for cancer therapy. First, MVA is an excellent inducer of innate immune responses leading to type I interferon secretion and induction of T helper cell type 1 (Th1) immune responses. Second, it elicits robust and durable humoral and cellular immunity against vector-encoded heterologous antigens. Third, MVA has enormous genomic flexibility, which allows for the expression of multiple antigenic and costimulatory entities. And fourth, its replication deficit in human cells ensures a excellent safety profile. In this review, we summarize the current understanding of how MVA induces innate and adaptive immune responses. Furthermore, we will give an overview of the tumor-associated antigens and immunomodulatory molecules that have been used to armor MVA and describe their clinical use. Finally, the route of MVA immunization and its impact on therapeutic efficacy depending on the immunomodulatory molecules expressed will be discussed.

Preclinical development of a first-in-class vaccine encoding HER2, Brachyury and CD40L for antibody enhanced tumor eradication

The induction of antiviral innate immunity by systemic immunization with live virus can be employed to positively impact the response to therapeutic vaccination. We previously demonstrated that systemic immunization with a non-replicating MVA encoding CD40 ligand (CD40L) enhances innate immune cell activation and function, and triggers potent antitumor CD8⁺ T cell responses in different murine tumor models. Antitumor efficacy was increased when combined with tumor targeting antibodies. Here we report the development of TAEK-VAC-HerBy (TVH), a first-in-class human tumor antibody enhanced killing (TAEK) vaccine based on the non-replicating MVA-BN viral vector. It encodes the membrane bound form of human CD40L, HER2 and the transcription factor Brachyury. TVH is designed for therapeutic use in HER2- or Brachyury-expressing cancer patients in combination with tumor targeting antibodies. To preclude possible oncogenic activities in infected cells and to prevent binding of vaccine-encoded HER2 by monoclonal antibodies trastuzumab and pertuzumab, genetic modifications of HER2 were introduced in the vaccine. Brachyury was genetically modified to prevent nuclear localization of the protein thereby inhibiting its transcriptional activity. CD40L encoded in TVH enhanced human leukocyte activation and cytokine secretion in vitro. Lastly, TVH intravenous administration to non-human primates was proven immunogenic and safe in a repeat-dose toxicity study. Nonclinical data presented here highlight TVH as a first-in-class immunotherapeutic vaccine platform currently under clinical investigation.

Functional analysis of peripheral and intratumoral neoantigen-specific TCRs identified in a patient with melanoma

Background

Neoantigens derived from somatic mutations correlate with therapeutic responses mediated by treatment with immune checkpoint inhibitors. Neoantigens are therefore highly attractive targets for the development of therapeutic approaches in personalized medicine, although many aspects of their quality and associated immune responses are not yet well understood. In a case study of metastatic malignant melanoma, we aimed to perform an in-depth characterization of neoantigens and respective T-cell responses in the context of immune checkpoint modulation.

Methods

Three neoantigens, which we identified either by immunopeptidomics or in silico prediction, were investigated using binding affinity analyses and structural simulations. We isolated seven T-cell receptors (TCRs) from the patient’s immune repertoire recognizing these antigens. TCRs were compared in vitro by multiparametric analyses including functional avidity, multicytokine secretion, and cross-reactivity screenings. A xenograft mouse model served to study in vivo functionality of selected TCRs. We investigated the patient’s TCR repertoire in blood and different tumor-related tissues over 3 years using TCR beta deep sequencing.

Results

Selected mutated peptide ligands with proven immunogenicity showed similar binding affinities to the human leukocyte antigen complex and comparable disparity to their wild-type counterparts in molecular dynamic simulations. Nevertheless, isolated TCRs recognizing these antigens demonstrated distinct patterns in functionality and frequency. TCRs with lower functional avidity showed at least equal antitumor immune responses in vivo. Moreover, they occurred at high frequencies and particularly demonstrated long-term persistence within tumor tissues, lymph nodes and various blood samples associated with a reduced activation pattern on primary in vitro stimulation.

Conclusions

We performed a so far unique fine characterization of neoantigen-specific T-cell responses revealing defined reactivity patterns of neoantigen-specific TCRs. Our data highlight qualitative differences of these TCRs associated with function and longevity of respective T cells. Such features need to be considered for further optimization of neoantigen targeting including adoptive T-cell therapies using TCR-transgenic T cells.

Abstract B41: BRAF targeting sensitizes resistant melanoma to cytotoxic T cells

Although treatment of combination therapy with BRAF and MEK inhibitors in patient with melanoma has shown longer duration of response and higher rate of tumor responses, recurrence of tumor from dual targeted therapy in patients with metastatic melanoma has still remained a challenge to overcome. Here, we provide new therapeutic approaches for BRAF inhibitors-resistant melanoma model that upregulation of mannose-6-phosphate receptor (M6PR) on melanoma by treatment of BRAF inhibitors enhances tumor cytotoxicity level via Granzyme B uptake, which is major component of cytotoxic activity of cytotoxic T lymphocytes (CTLs). Our results demonstrate that treatment of BRAF inhibitor increases M6PR expression temporally in both sensitive and resistant BRAFi melanoma cell lines as well as tumor-bearing mouse models (NOD/SCID). Cytotoxic activity of human melanoma cells by co-culture with patient-derived tumor-infiltrating lymphocytes (TILs) shows correlation with M6PR expression level. Furthermore, treatment of mice bearing resistant tumor with BRAFi enhances the antitumor effect of adaptive TILs transfer. In pilot clinical trials of 16 patients with metastatic melanoma, our results support that administration of BRAF inhibitor to patient shows high level of M6PR expression on tumor tissues. Also, combination treatment of BRAF inhibitor and adaptive cell transfer with patient-derived TILs shows promising clinical results in terms of longer response and tumor-free survival. Taken together, BRAF targeted therapy upregulates M6PR level, which enhances activity of TILs to kill resistant melanoma, providing new therapeutic approaches for patients who have recurrence melanoma.

Note: This abstract was not presented at the conference.

Citation Format: Cigdem Atay, Taekyoung Kwak, Sergio Lavilla-Alonso, Allison Richards, Valerie Moberg, Shari Pilon-Thomas, Michael Schell, Jane L. Messina, Vito W. Rebecca, Gao Zhang, Jeffrey S. Weber, Meenhard Herlyn, Amod A. Sarnaik, Dmitry I. Gabrilovich. BRAF targeting sensitizes resistant melanoma to cytotoxic T cells [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B41.

The prognostic and predictive significance of plasma type 1 plasminogen activator inhibitor and endoglin in metastatic colorectal cancer patients treated with bevacizumab-containing chemotherapy

Aim

This study aims to evaluate the prognostic and predictive value of plasma plasminogen activator inhibitor-1 (PAI-1) and endoglin in metastatic colorectal cancer (mCRC) patients receiving chemotherapy with bevacizumab.

Materials and Methods

Between April 2012 and September 2013, 47 mCRC patients with a mean age of 58.5 ± 9.6 years were included in the study. Male-to-female ratio was 29/18. The baseline and posttreatment plasma PAI-1 and serum endoglin levels after 3 cycles of bevacizumab-containing chemotherapy were evaluated. The percent change between baseline and posttreatment levels after treatment was also recorded.

Results

The median follow-up duration was 26.6 months (range 1.8-70.2 months). The clinical benefit rate was 70% (partial response [32%], stable disease [38%]). Overall survival was 20.8 ± 1.5 months. The patients with progressive disease had statistically significantly higher baseline PAI-1 level (57.9 pg/mL vs. 29.9 pg/mL, P = 0.036). The percent change of the plasma PAI-1 level after the third cycle of treatment was also statistically significantly lower in those with clinical benefit (P = 0.035). However, there was no statistically significant difference in endoglin level and its change after therapy with respect to the response to treatment (P = 0.771 and P = 0.776, respectively). Plasma PAI-1 level had no statistically significant effect on survival (P = 0.709).

Conclusion

Baseline plasma PAI-1 level and its percent change with bevacizumab were shown to have statistically significant predictive value for the response to therapy whereas serum endoglin had no statistically significant predictive value for the response to therapy. However, neither PAI-1 nor endoglin had prognostic significance in mCRC.

BRAF Targeting Sensitizes Resistant Melanoma to Cytotoxic T Cells

PURPOSE

BRAF and MEK inhibitors (BRAFi and MEKi) are actively used for the treatment of metastatic melanoma in patients with BRAF^V600E mutation in their tumors. However, the development of resistance to BRAFi and MEKi remains a difficult clinical challenge with limited therapeutic options available to these patients. In this study, we investigated the mechanism and potential therapeutic utility of combination BRAFi and adoptive T-cell therapy (ACT) in melanoma resistant to BRAFi.

EXPERIMENTAL DESIGN

Investigations were performed in vitro and in vivo with various human melanoma cell lines sensitive and resistant to BRAFi as well as patient-derived xenografts (PDX) derived from patients. In addition, samples were evaluated from patients on a clinical trial of BRAFi in combination with ACT.

RESULTS

Herein we report that in human melanoma cell lines, senstitive and resistant to BRAFi and in PDX from patients who progressed on BRAFi and MEKi therapy, BRAFi caused transient upregulation of mannose-6-phosphate receptor (M6PR). This sensitized tumor cells to CTLs via uptake of granzyme B, a main component of the cytotoxic activity of CTLs. Treatment of mice bearing resistant tumors with BRAFi enhanced the antitumor effect of patients' TILs. A pilot clinical trial of 16 patients with metastatic melanoma who were treated with the BRAFi vemurafenib followed by therapy with TILs demonstrated a significant increase of M6PR expression on tumors during vemurafenib treatment.

CONCLUSIONS

BRAF-targeted therapy sensitized resistant melanoma cells to CTLs, which opens new therapeutic opportunities for the treatment of patients with BRAF-resistant disease.See related commentary by Goff and Rosenberg, p. 2682.

Abstract CT015: Safety and long-term efficacy of radioligand therapy using Lu-177 labeled PSMA ligands in metastatic prostate cancer: A single center experience over 5 years

Aim: Metastatic prostate cancer (mPC) has still a poor prognosis. First- and second-line chemotherapy with docetaxel or cabazitaxel is often toxic and prolongs life by only a few months. Also novel agents like abiraterone, enzalutamide or Ra-223-chloride confer a limited survival benefit. Prostate-specific membrane antigen (PSMA) is a glutamate carboxypeptidase II overexpressed especially in poorly differentiated prostate cancer (1) and is a very attractive target for diagnosis and therapy (theranostics) with radiolabeled small molecules. Internalization and retention within the tumor cell provides very promising and highly selective treatment effects of multiple metastases with PSMA radioligand therapy (PRLT) (2-5).

Methods: 224 mPC patients (mean age 71 years, mean Gleason score 8), screened by Ga-68 PSMA or F-18 DCFPyl PET/CT imaging, were treated with 1 - 9 cycles (3.5 - 12 GBq Lu-177 PSMA per cycle) between April 2013 and October 2017 and included in the intention to treat analysis with a median follow-up time of 16 months (3 - 55). Previous treatments were surgery (154), external beam radiation (151), chemotherapy (110), androgen deprivation (206) and Ra-223 chloride (19). The serum prostate antigen (PSA) levels were monitored before and after therapy. Response to therapy was also determined by RECIST as well as according to molecular imaging criteria using standardized uptake values (SUV) on Ga-68 PSMA PET/CT studies. Hematological and organ toxicity was documented according to CTCAE v4.03.

Results: Reduction in serum PSA was observed in 157/224 (70%) patients; 121/224 patients (54%) demonstrated a PSA decline by >50%, best response was complete remission with undetectable PSA. Ga-68 PSMA PET/CT after at least 2 PRLT cycles in 200 patients demonstrated complete remission in 6 (3%), partial remission in 70 (35%), stable disease in 55 (27.5%) and progressive disease in 69 (34.5%) patients. RECIST revealed 46 (23%) partial remissions, 6 (3%) complete remissions, 84 (42%) with stable disease and 64 (32%) disease progressions. The median overall survival was 27 months. Median progression-free survival was 18 months. No severe (G3-4) bone marrow toxicity was observed and patients didn't show any evidence of nephrotoxicity or any other significant organ toxicity. Mild xerostomia occurred in less than 3% of all patients.

Conclusion: Lu-177 PSMA radioligand therapy appears to be effective for the treatment of metastatic prostate cancer with only minimal toxicity, offering a significant benefit in overall and progression-free survival even in patients whose disease had progressed despite all standard treatments. Randomized controlled studies are required to best determine the place of this theranostic approach in the management of mPC.

Citation Format: Harshad R. Kulkarni, Thomas Langbein, C Atay, Aviral Singh, Christiane Schuchardt, Coline Lehmann, Martin Pomper, Kenneth J. Pienta, Richard P. Baum. Safety and long-term efficacy of radioligand therapy using Lu-177 labeled PSMA ligands in metastatic prostate cancer: A single center experience over 5 years [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT015.

Abstract 1543: Upregulation of mannose 6-phosphate receptor (MPR) has a potential to increase the efficacy of combined therapy for melanoma patients

BRAF -targeting therapy demonstrates impressive clinical response in patients with metastatic melanoma. However, patients quickly develop resistance associated with rapid tumor progression. Therefore, additional therapeutic approaches are necessary. Our group has previously shown that transient induction of cation-independent mannose 6-phosphate receptor (MPR) is important for the antitumor effect of chemo-immunotherapy. In this study, we aimed to decipher the role of MPR during possible combination therapy of BRAF inhibitor with adoptive T-cell therapy of BRAF inhibitor-resistant melanoma. For this aim, we have used PLX4720 as a BRAFV600E inhibitor and observed that in vitro PLX4720 treatment of human V600E-positive melanoma cells, including WM-35, SK-Mel-624 and WM983B, resulted in a dose-dependent upregulation of MPR on the cell surface. Importantly, increased levels of MPR on the cell surface induced the uptake of recombinant Granzyme B, which is a major mechanism of cell killing by cytotoxic T cells (CTL). We found that PLX4720 treatment rendered WM35 cells more prone to lysis by HLA-matching tumor-infiltrating lymphocytes (TILs) and increased cell killing is not due to PLX4720 treatment itself but increased levels of MPR on the cell surface. In order to prove this, we generated MPR-overexpressing WM35 cell line and showed that upregulation of MPR, independently of PLX4720 treatment, sensitizes melanoma cells for T cell killing in vitro. We further showed that PLX4720 treatment leads to upregulation of MPR in vivo by a mouse model bearing xenograft WM35-derived subcutaneous tumors as well. According to our data, 3 days of PLX4720 treatment is enough to induce MPR in tumors and this effect continues up to 6 days after 5 days treatment ends. Unexpectedly, we found that PLX4720 caused upregulation of MPR in resistant cell lines and that those cell lines became more sensitive to cytotoxic effect of TILs. Thus, our data suggest that adoptive T-cell therapy can be potentially effective in melanoma resistant to BRAF inhibitor. (This study is supported by NIH grant P50 CA168536.)

Citation Format: Cigdem Atay, Sergio Lavilla-Alonso, Dmitry Gabrilovich. Upregulation of mannose 6-phosphate receptor (MPR) has a potential to increase the efficacy of combined therapy for melanoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1543.

The expression of Forkhead transcription factors in decidua and placenta in patients with missed abortion

BACKGROUND

Forkhead transcription factors 3a (FOXO3a) has pleiotropic biological functions in the female reproductive tract. FOXO3a has a function in decidualization, in placental development, and also in inhibition of apoptosis. This study aims to investigate a possible role of FOXO3a in missed abortion.

MATERIALS AND METHODS

Decidual and placental tissue samples were obtained from the women with unwanted pregnancy as the control group and with missed abortion as the patient group. Immunohistochemistry technique was utilized to compare FOXO3a expression of the decidual cells in uterine decidual stroma and cytotrophoblast-syncytiotrophoblast cells in placental villous stroma. Immunohistochemistry was evaluated semiquantitatively utilizing the H-score technique. Results: It was demonstrated that H-Scores of FOXO3a expression in both uterine decidual stroma were increased in the missed abortion group (255.83 +/- 12.41) than in the normal pregnancy group (133.33 +/- 17.43). It was also shown that there was no difference between non-decidual area of the endometrium of the normal pregnancy and the missed abortion group (30.33 +/- 4.32; 39.66 +/- 14.30, respectively) and placental villous stroma (13.00 +/- 1.89; 13.00 +/- 1.67, respectively). However, the immunoreactivity of cytotrophoblast and syncytiotrophoblast cells significantly increased in the missed abortion group (18.83+1.47; 322.00 +/- 6.06, respectively) than in the normal pregnancy group (11.00 +/- 1.26; 254.00 +/- 8.17, respectively) (p < 0.05).

CONCLUSION

These data support the hypothesis that increased FOXO3a expression in missed abortion may prevent the discharge of dead fetus to maintain decidualization, prevention of oxidative stress, immunomodulation, and inhibition of apoptosis.

A comparison of the molecular distribution of proangiogenic factors in endometrium of missed abortions and of voluntary first trimester termination cases

OBJECTIVE

The authors aimed to evaluate the angiogenic changes that occur in the cases with missed abortions compared with the voluntary termination of pregnancy as control group, with this controlled clinical study.

MATERIALS AND METHODS

The study included fifteen healthy volunteer women with unwanted pregnancy less than 10th gestational week in an academic research environment. The patients were 19 women between 6th and 11th gestational weeks diagnosed with missed abortion as the patient group. Immunohistochemistry was utilized to examine temporal and spatial expression of vascular endothelial growth factor (VEGF) and their two receptors: VEGF-R1 (Flt-1) and VEGF-R2 (Flk-1/KDR), and Trombospondin-1, eNOS, iNOS, and HIF-1α in the both deciduas and placenta of the both groups.

RESULTS

This study discovered the significant difference (p < 0.005) between the groups of controlled and missed abortion in the decidual and placental cell components, and has put forward that thrombospondin and iNOS have an impact on abortion through antiangiogenic effect in cases of missed abortions.

CONCLUSIONS

The potential role of molecules affecting angiogenesis in the etiology of missed abortion has been evaluated and the authors aimed for this to be a guide for studies on further treatments and on the prevention of the development of missed abortions.

Shock the heat shock network

The targeting of tumors is made possible through establishing protein signatures specific for each cancer type. The recent recognition of the higher expression levels of HSP90 and its accumulation in tumor cell mitochondria has made the HSP90 network a feasible target for neutralization. HSP90 antagonizes the mitochondrial permeability transition,blocking cytochrome c release and apoptosis. In this issue of the JCI, Kang et al. report the synthesis of Gamitrinibs, which target mitochondrially localized HSP90, specifically killing human cancer cell lines, and provide a fresh approach for cancer treatment.

Diagnostic value of blood D-dimer level in acute mesenteric ischaemia in the rat: an experimental study

OBJECTIVE

The high mortality rate of mesenteric ischaemia is mainly due to delay in diagnosis. For this reason, it is of great importance to find a specific and rapidly elevating marker. The present study investigated the diagnostic value of blood D-dimer level as a potential marker for acute mesenteric ischaemia in a rat model.

METHODS

Thirty male Wistar albino rats were divided into three groups. Basal D-dimer and L-lactate levels were determined in the non-operative control group (I). In the operated control group (II), the superior mesenteric artery was simply manipulated, while the artery was ligated in Group III. Blood samples were drawn in all groups for D-dimer and L-lactate assays.

RESULTS

Both Group II (p=0.016) and Group III (p=0.001) had significantly higher mean D-dimer levels in the first postoperative hour compared with the basal level in Group I. However, there was no difference between the levels in Groups II and III. The mean level in Group II in the sixth hour had dropped to a statistically insignificant level compared with the basal value, while the mean value in Group III kept rising during this period (p=0.001). Nevertheless, there was no significant difference between Groups II and III. On the other hand, the mean L-lactate level in the first postoperative hour in Group III was significantly higher than the basal level in Group I (p=0.003). No significant rises were recorded in Group II in the first and sixth postoperative hours. The difference between Groups II and III in the first hour was significant (p=0.005). Group III also had significantly higher mean serum L-lactate value in the sixth hour compared with both the basal value in Group I (p=0.001) and the sixth-hour value in Group II (p=0.003).

CONCLUSION

These results do not adequately support the use of blood D-dimer level as an independent parameter in the diagnosis of mesenteric ischaemia due to arterial thrombosis. However, this parameter can be used together with other tests in eliminating the possibility of a thromboembolic event.