MD Anderson Phase III Randomized Preoperative Stereotactic Radiosurgery (SRS) vs. Postoperative SRS for Brain Metastases Trial

PURPOSE/OBJECTIVE(S)

Postoperative stereotactic radiation therapy/radiosurgery (SRT/SRS) is being evaluated in comparison to Preoperative SRT for brain metastases (mets) in a limited number of prospective clinical trials. Our objective is to address the significant knowledge gap concerning the logistics of preoperative SRT in comparison to postoperative SRT in a randomized controlled study.

MATERIALS/METHODS

Patients with brain mets with at least 1 surgically operable met were randomized (1:1) to Preop vs Postop SRT. In this abstract, we present non-primary endpoint data on the trial concept and logistics of treatment for this data safety monitoring board reviewed study. Patients enrolled had 1-2 lesions resected and <15 lesions treated at time of SRT to best reflect the standard population that receive SRT and surgery at our institution.

RESULTS

From 12/2018 to 12/2022, 99 patients with 1-2 operable brain mets were enrolled and randomized to Preop (n = 49) or Postop (n = 50) SRT. Males represented 56% of the cohort compared to females, and <25% were age 18-49 years, while 27%, 29, and 19% respectively were 50-59, 60-69, and > = 70. The most frequent histologies enrolled were lung (29%), renal cell (15%), melanoma (14%), and breast (11%) cancers. The majority of patients (83%) had 1-4 brain mets on their baseline MRI and 91% subsequently had a single lesion resected. Seventy-nine patients completed both SRT and surgery, while 9% received no therapy due to drop out before study therapy initiation. Among patients receiving both therapies in the combined cohort, 68% received a non-invasive stereotactic radiosurgery instrument to the randomized cavity lesion compared to 32% receiving LINAC based SRT. Treatment of the lesion or cavity with single fraction SRT was 51% in the Preop arm vs 31% in the Postop arm. Multi-fraction (3-5 SRT) was 67% in the Postop cohort in contrast to 47% in the Preop cohort. Time from randomization to RT was 5.6 days and 33.7 days in the Preop and Postop cohorts respectively, and for surgery was 10.2 days vs 12.9 days in the Postop vs Preop cohorts. The average time from RT to surgery was 7.3 days in the Preop arm and 23.5 days in the Postop arm (to allow for incisional healing time).

CONCLUSION

In one of the early initiated randomized prospective cohorts of Preop vs Postop SRT, we demonstrated logistical feasibility with an efficient clinical trial workflow for study treatment. Differences in Preop vs Postop logistics reflect clinical practice differences in time-to-treatment. Therapy with various modalities reflected real-world practice and possibly provider preferences in technique when addressing the nature of delineating cavities and changes in cavity volume with regard to fractionation. Independent of the primary outcomes, our data provides insights in the practical management of patients receiving these two modalities of therapy, and further data at the completion of trial will address relevant primary outcomes.

Crossover-effects in technical skills between laparoscopy and robot-assisted surgery

INTRODUCTION

Robot-assisted surgery is often performed by experienced laparoscopic surgeons. However, this technique requires a different set of technical skills and surgeons are expected to alternate between these approaches. The aim of this study is to investigate the crossover effects when switching between laparoscopic and robot-assisted surgery.

METHODS

An international multicentre crossover study was conducted. Trainees with distinctly different levels of experience were divided into three groups (novice, intermediate, expert). Each trainee performed six trials of a standardized suturing task using a laparoscopic box trainer and six trials using the da Vinci surgical robot. Both systems were equipped with the ForceSense system, measuring five force-based parameters for objective assessment of tissue handling skills. Statistical comparison was done between the sixth and seventh trial to identify transition effects. Unexpected changes in parameter outcomes after the seventh trial were further investigated.

RESULTS

A total of 720 trials, performed by 60 participants, were analysed. The expert group increased their tissue handling forces with 46% (maximum impulse 11.5 N/s to 16.8 N/s, p = 0.05), when switching from robot-assisted surgery to laparoscopy. When switching from laparoscopy to robot-assisted surgery, intermediates and experts significantly decreased in motion efficiency (time (sec), resp. 68 vs. 100, p = 0.05, and 44 vs. 84, p = 0.05). Further investigation between the seventh and ninth trial showed that the intermediate group increased their force exertion with 78% (5.1 N vs. 9.1 N, p = 0.04), when switching to robot-assisted surgery.

CONCLUSION

The crossover effects in technical skills between laparoscopic and robot-assisted surgery are highly depended on the prior experience with laparoscopic surgery. Where experts can alternate between approaches without impairment of technical skills, novices and intermediates should be aware of decay in efficiency of movement and tissue handling skills that could impact patient safety. Therefore, additional simulation training is advised to prevent from undesired events.

Abstract 5788: Single-cell and spatial transcriptomic mapping of human renal cell carcinoma brain metastases uncovers actionable immune-resistance targets

Introduction: The discovery of immune checkpoint inhibitors has revolutionized metastatic renal cell carcinoma (RCC) treatment. However, in patients with RCC brain metastases, response rates are low and survival outcomes poor. To understand the tumor microenvironmental differences between primary kidney tumors, extracranial metastases, and brain metastases, we developed a detailed single-cell atlas of RCC brain metastases along with their matched extracranial and primary tumors.

Methods: We performed single-nucleus RNA-seq on 27 samples (nearly 200,000 cells) from RCC patients; samples included 14 brain metastases, 8 matched primary kidney tumors, and 5 matched extracranial metastases. We performed multiplex IHC to validate selected transcriptomic findings. We used Nanostring CosMx 960-plex RNA spatial molecular imaging technique on selected samples to validate cellular interactions in a spatial context.

Results: We established a multi-tissue single-cell atlas of RCC brain metastases by identifying 9 major and 37 minor malignant, immune, and stromal cell clusters. Brain metastases had higher neuronal and glial cells interacting with immune and tumor cells. Brain metastasis tumor cells were also transcriptomically reprogrammed to adapt to the brain microenvironment through enrichment of MYC targets, MTORC1 signaling, epithelial-mesenchymal transition, fatty-acid metabolism, oxidative phosphorylation, and reactive oxygen species pathways. Moreover, cell-to-cell communication and downstream target gene expression analyses showed that brain metastasis tumor cells expressed ligands and receptors that induce tumor cell proliferation in both autocrine and paracrine fashions. Among T-cell populations, we found fewer proliferating cytotoxic T lymphocytes in the brain than in other sites. Moreover, T cells in brain metastases expressed higher levels of several targetable inhibitory checkpoints than did extracranial metastases. In addition, we found that naïve/memory T cells in brain metastases were a favorable prognostic marker for overall survival after craniotomy. Our characterization of myeloid cell populations across the 3 disease sites found fewer dendritic cells and monocytes in the brain compared to other sites. Macrophages in brain metastases more highly expressed an M2 immunosuppressive gene signature than did those in primary RCC tumors.

Conclusion: Our findings from the largest single-cell atlas of RCC brain metastases with matched primary and extracranial metastases suggest several unique targetable, immunosuppressive biological mechanisms in the brain microenvironment. These results provide a foundation for a deeper understanding of RCC brain metastasis biology and can serve as a resource for the scientific community to further explore therapeutically targetable tumor and immune-related mechanisms.

Citation Format: Elshad Hasanov, Truong Nguyen Anh Lam, Jerome Lin, Patrick K. Reville, Merve Hasanov, Anna K. Casasent, David Shih, Sahin Hanalioglu, Mehmet Asim Bilen, Omar Alhalabi, Berrin Babaoglu, Baylar Baylarov, Adeboye O. Osunkoya, Lisa M. Norberg, Joy Gumin, Tuan M. Tran, Jianzhuo Li, Anh G. Hoang, Haidee D. Chancoco, Brittany C. Parker Kerrigan, Erika J. Thompson, Betty YS Kim, Dima Suki, Melike Mut, Figen Soylemezoglu, Giannicola Genovese, Kadir C. Akdemir, Hussain A. Tawbi, Nizar M. Tannir, Florencia McAllister, Michael A. Davies, Padmanee Sharma, Jason Huse, Frederick Lang, Nicholas Navin, Eric Jonasch. Single-cell and spatial transcriptomic mapping of human renal cell carcinoma brain metastases uncovers actionable immune-resistance targets [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5788.

Abstract 5871: Pan-cancer myeloid cell analysis at the single cell level reveals the influence of distinct organ sites in myeloid cell phenotypes and support targeting S100A4 to reverse immune suppression

With abundant pro-tumorigenic myeloid cells and few tumoricidal tumor-infiltrating lymphocytes (&lt;5%), GBM is representative of “immune cold” tumors. As such, many different types of immunotherapies have failed to show significant benefits for most glioma patients. Hence, a better understanding of drivers of the immune suppressive microenvironment in GBM and other immune cold tumors is urgently needed to guide future immunotherapy development and application. We recently analyzed 201,986 human glioma and immune cells from 44 tissue fragments from 18 human glioma patients, and present a comprehensive and high-resolution cellular, molecular, and spatial heterogeneity atlas of human glioma. We report an extensive spatial and molecular heterogeneity of glioma and immune cells within the same patient. In addition, we discovered that cell:cell communication between glioma:myeloid cells is considerably more robust than glioma:T-cells, indicating that myeloid cells form a communication hub in vivo. To gain a deeper understanding of these important immune cells, we analyzed 83,479 glioma-infiltrating myeloid cells and identified 9 molecularly distinct myeloid subtypes: 3 microglia subtypes, 3 bone marrow-derived macrophage (BMDM) subtypes, MDSCs, neutrophils, and dendritic cells. Notably, we found that five of these myeloid cell subtype gene signatures are significant predictors of glioma patient survival, independent of glioma cell mutational profiles or gene expression patterns. Leveraging our dataset, we also identified a novel immunotherapy target that is highly expressed in immune-suppressive macrophages and T cells but not in anti-tumor leukocytes: S100A4. We provide both in vitro and in vivo evidence that S100a4 deletion in stromal cells is sufficient to reprogram the immune microenvironment and significantly extend the survival of two independent glioma models. To broaden the potential impact of targeting S100A4 as a selective modulator of immune suppressive leukocytes, we compared the molecular signatures of glioma-associated myeloid cells to those from 12 other cancer types and peripheral blood myeloid cells. We found that S100A4 expression pattern is highly consistent among all tumor types, where its expression is highest in the monocytes and MDSCs and low in most DCs and tissue-resident macrophages. Our preliminary analysis also shows that myeloid cells in gliomas are molecularly distinct from corresponding cell types in other cancers, strongly indicating the role brain microenvironment in influencing the infiltrating BMDM maturation and polarization.

Citation Format: Nourhan Abdelfattah, Parveen Kumar, Caiyi Wang, Jia-Shiun Leu, David Baskin, William Flynn, Ruli Gao, Kumar Pichumani, Omkar Ijare, Stephanie Wood, Suzanne Powell, David Haviland, Brittany Parker Kerrigan, Frederick Lang, Sujit Prabhu, Kristin Huntoon, Wen Jiang, Betty Kim, Joshy George, Kyuson Yun. Pan-cancer myeloid cell analysis at the single cell level reveals the influence of distinct organ sites in myeloid cell phenotypes and support targeting S100A4 to reverse immune suppression. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5871.

Video-based learning of coping strategies for common errors improves laparoscopy training-a randomized study

AIMS

The aim of this study was to investigate whether shifting the focus to solution orientation and developing coping strategies for common errors could increase the efficiency of laparoscopic training and influence learning motivation. The concept of coping has been particularly defined by the psychologist Richard Lazarus [Lazarus and Folkman in Stress, appraisal, and coping, Springer publishing company, New York, 1984]. Based on this model, we examined the use of observational learning with a coping model for its effectiveness as a basic teaching model in laparoscopic training.

METHODS

55 laparoscopically naive medical students learned a standardized laparoscopic knot tying technique with video-based instructions. The control group was only offered a mastery video that showed the ideal technique and was free from mistakes. The intervention group was instructed on active error analysis and watched freely selectable videos of common errors including solution strategies (coping model) in addition to the mastery videos.

RESULTS

There was no statistically significant difference between the intervention and control groups for number of knot tying attempts until proficiency was reached (18.8 ± 5.5 vs. 21.3 ± 6.5, p = 0.142). However, there was a significantly higher fraction of knots achieving technical proficiency in the intervention group after first use of the coping model (0.7 ± 0.1 vs. 0.6 ± 0.2, p = 0.026). Additionally, the proportion of blinded attempts that met the criteria for technical proficiency was significantly higher for the intervention group at 60.9% vs. 38.0% in control group (p = 0.021). The motivational subscore "interest" of the validated score on current motivation (QCM) was significantly higher for the intervention group (p = 0.032), as well as subjective learning benefit (p = 0.002) and error awareness (p < 0.001).

CONCLUSION

Using video-based learning of coping strategies for common errors improves learning motivation and understanding of the technique with a significant difference in its qualitative implementation in laparoscopy training. The ability to think in a solution-oriented, independent way is necessary in surgery in order to recognize and adequately deal with technical difficulties and complications.

Force-based assessment of tissue handling skills in simulation training for robot-assisted surgery

INTRODUCTION

Although robotic-assisted surgery is increasingly performed, objective assessment of technical skills is lacking. The aim of this study is to provide validity evidence for objective assessment of technical skills for robotic-assisted surgery.

METHODS

An international multicenter study was conducted with participants from the academic hospitals Heidelberg University Hospital (Germany, Heidelberg) and the Amsterdam University Medical Centers (The Netherlands, Amsterdam). Trainees with distinctly different levels of robotic surgery experience were divided into three groups (novice, intermediate, expert) and enrolled in a training curriculum. Each trainee performed six trials of a standardized suturing task using the da Vinci Surgical System. Using the ForceSense system, five force-based parameters were analyzed, for objective assessment of tissue handling skills. Mann-Whitney U test and linear regression were used to analyze performance differences and the Wilcoxon signed-rank test to analyze skills progression.

RESULTS

A total of 360 trials, performed by 60 participants, were analyzed. Significant differences between the novices, intermediates and experts were observed regarding the total completion time (41 s vs 29 s vs 22 s p = 0.003), mean non zero force (29 N vs 33 N vs 19 N p = 0.032), maximum impulse (40 Ns vs 31 Ns vs 20 Ns p = 0.001) and force volume (38 N³ vs 32 N³ vs 22 N³ p = 0.018). Furthermore, the experts showed better results in mean non-zero force (22 N vs 13 N p = 0.015), maximum impulse (24 Ns vs 17 Ns p = 0.043) and force volume (25 N³ vs 16 N³ p = 0.025) compared to the intermediates (p ≤ 0.05). Lastly, learning curve improvement was observed for the total task completion time, mean non-zero force, maximum impulse and force volume (p ≤ 0.05).

CONCLUSION

Construct validity for force-based assessment of tissue handling skills in robot-assisted surgery is established. It is advised to incorporate objective assessment and feedback in robot-assisted surgery training programs to determine technical proficiency and, potentially, to prevent tissue trauma.

[Traumatology-an interdisciplinary task: exclusively for educational purposes?]

BACKGROUND

Traumatology of the head and neck region is not only a part of otorhinolaryngology, but also has a large overlap with neighboring disciplines of the head and neck region. In Freiburg, an interdisciplinary lecture on "ENT emergencies" was implemented in the 21/22 winter semester. The aim was to provide an even more realistic view on interdisciplinary patient care and to make evident the areas of intersection of four of the major head disciplines (otorhinolaryngology, neurosurgery, ophthalmology, and maxillofacial surgery).

MATERIALS AND METHODS

A new, special lecture in otorhinolaryngology was implemented as part of the regular online lecture series accompanying the semester. With reference to the clinical care of ENT emergencies, possible overlaps with neighboring disciplines were identified and explained by the discipline representatives or discussed in front of and with the auditorium. At the end of the semester, all participating students (n = 173) were invited to evaluate the seminar using the survey tool "EvaSys" (EvaSys GmbH, Lüneburg, Germany). In total, 78 students participated in the evaluation process.

RESULTS

The new lecture concept was very well accepted and immediately ranked top among the interdisciplinary lecture titles within the ENT lecture series. The clear communication of the term "interdisciplinarity" in the sense of a complementary clinical cooperation was also very successful and was appreciated accordingly by students during the evaluation process.

CONCLUSION

Pragmatic presentation of ideal clinical patient care using an interdisciplinary approach is possible within the regular ENT lecture series. This realistic portrayal, beyond any technical and/or professional differences, is of great interest to students and is considered clinically relevant. Thus, interdisciplinary lectures provide a valuable tool to teach the fundamental values of clinical interdisciplinary management for the best possible patient care.

IMMU-39. NANOPARTICLE TREATMENT REBALANCES IMMUNODOMINANCE OF ANTI-VIRUS IMMUNITY TO ENHANCE ANTI-TUMOR IMMUNITY DURING ONCOLYTIC ADENOVIRUS THERAPY IN SOLID TUMORS

Oncolytic virotherapy shows great potential for treating brain tumors and other solid tumors that metastasize to the brain. A phase I clinical trial testing the oncolytic adenovirus Delta-24-RGD (DNX-2401) in patients with recurrent malignant gliomas demonstrated significant clinical benefits for a subset of patients, and another phase I trial testing Delta-24-RGD in patients with pediatric brain tumors also indicated similar clinical benefits. However, virus injection in tumors initiates both anti-virus and anti-tumor immune responses by activating respective clones of CD8+ T-cells, which compete for limited resources for clonal expansion. Expansion of T-cells against highly immunogenic viral antigens might limit the expansion of subdominant clones against tumor antigens. We hypothesized that inducing immune tolerance for the dominant viral antigens will allow the expansion of previously subdominant tumor-specific T-cells. In this work, we observed that nanoparticles encapsulating adenoviral antigens successfully induced immune tolerance for viral antigens. These nanoparticles were taken up by liver resident macrophages, which are involved in maintaining peripheral immune tolerance. RNA-sequencing revealed that T-cells recognizing the encapsulated antigens had unique transcriptome signatures with upregulation of genes specifically involved in peripheral immune tolerance, including immune coinhibitory molecules. Virus-specific immune tolerance using nanoparticles redirected the focus of the immune response towards antigens for melanoma as measured by interferon-gamma secretion (P &lt; 0.0001). Reduction of virus-specific T-cells and simultaneous expansion of tumor-specific T-cell clones were confirmed with tetramer staining (P &lt; 0.05). Importantly, virotherapy in combination with nanoparticle-induced immune tolerance towards viral antigens increased the percentage of long-term survivors compared to virus treatment alone (100% versus 50%). Our data provide the basis to develop future clinical trials that aim to maximize the potential of cancer virotherapy in solid tumors.

EXTH-62. EXAMINATION OF THE TUMOR MICROENVIRONMENT OF GLIOMAS TREATED WITH VIROIMMUNOTHERAPY REVEALS THE PRODUCTION OF ONCOMETABOLITES LEADING TO IMPROVED THERAPEUTIC STRATEGIES

Oncolytic viruses are considered part of immunotherapy and have shown promise in preclinical experiments and clinical trials in a small fraction of patients. To improve the response rate, it is necessary to reshape the tumor microenvironment that shields the tumor from the immune system of the patient. We engineered Delta-24-RGDOX (DNX-2440), an oncolytic adenovirus to express the T-cell activator OX40L, which triggered, in murine glioblastoma models, a dramatic reshaping of the tumor microenvironment dominated by changes in immune processes in an RNA-seq analysis of ingenuity pathways. Paradoxically, network analyses also revealed that Delta-24-RGDOX induced robust activation of the cytokine-driven immunosuppressive IDO-Kynurenine-AhR circuitry, indicating a potential mechanism of resistance of gliomas to oncolytic virotherapy. To reverse this immunosuppression, we combined Delta-24-RGDOX with clinically relevant IDO inhibitors to treat glioma-bearing mice. The combined therapy decreased the activation of the IDO network without affecting viral activity. Flow cytometry assays revealed a decrease in the presence of the immunosuppressive cell populations, MDSCs and Tregs, which presence was higher in Delta-24-RGDOX-treated tumors. These data were further confirmed in gene set enrichment analyses. Functional co-culture studies showed that the combined therapy activated splenocytes against tumor antigens and that this activation was reversed by Kynurenine. Importantly, the combination treatment eradicated the tumors in a CD4-dependent manner and significantly prolonged the survival of glioma-bearing mice. Altogether, these studies indicate that the combination treatment promotes an adaptive immune response while decreasing the immunosuppression caused by the virus-induced IDO activation. Furthermore, our data identified the striking role of immunosuppressive pathways in the resistance of gliomas to oncolytic virotherapy. Specifically, the activity of the tumor microenvironment IDO circuitry was responsible, at least partially, for the remodeling of local immunosuppression after tumor infection. Combining molecular and immune-related therapies may improve outcomes in human gliomas treated with virotherapy.

IMMU-11. NONO IS A NEW ADENOVIRUS SENSOR: IMPLICATION FOR VIROTHERAPY

The median survival for GBM patients is 15 months with a five-year survival rate of less than 10%. Current conventional and experimental treatments, including immune checkpoint blockade, have not improved outcomes in the vast majority of glioma patients. Oncolytic viruses (OVs) are designed to specifically infect and lyse cancer cells to elicit an anti-tumor immune response. In a clinical trial developed by the MDACC team, 20% of GBM patients treated with the oncolytic adenovirus Delta-24-RGD showed complete response and survival longer than three years (NCT00805376). Although these studies have shown that robust immune responses can be invoked using oncolytic virotherapy, the molecular mechanisms underlying OV-mediated anti-tumor immunity remain elusive. Exposure to viruses by innate immune sensors induces protective antiviral immunity. Using bulk RNA sequencing of cells infected with adenovirus we identified the main upstream regulators of the innate immune response including IFN gamma, Interferon responsive genes 3 and 7, and STAT3. However, RNAseq unexpectedly uncovered NONO (Non-POU Domain Containing Octamer Binding) as the most relevant upstream regulator. In agreement with the RNAseq data, Protein analyses demonstrated the upregulation of NONO after adenovirus infection. In addition, immunofluorescence and confocal microscopy examination of the infected cells showed the overexpression and translocation to the nucleus of NONO upon virus infection. We are the first laboratory that has identified NONO as a sensor of adenovirus infection, which may have great significance for the future development of oncolytic viruses. Importantly, we discovered the network of proteins that are upregulated after NONO activation and, finally, we have established that changes in the expression level and subcellular localization of NONO are coincident in time during the infection of cultured cells. Future work is focused on examining the immunomodulatory functions of NONO in adenoviral infected tumors and subsequent generation of NONO-resistant oncolytic adenovirus.

EXTH-94. LOCALIZED INTRATUMORAL TREATMENT WITH ADOPTIVE T CELL THERAPY FOLLOWED BY ONCOLYTIC ADENOVIRUS DELTA-24-RGDOX INDUCES SUSTAINABLE REGRESSION OF DISSEMINATED SOLID TUMORS THROUGH ANTIGEN SPREAD

Tumor-targeting biological therapies, including adoptive T cell therapy (ACT) and oncolytic viruses, are being tested clinically to address the challenges in treating advanced solid tumors with heterogeneity and immune suppressive microenvironment (TME). Since complementary properties of these two approaches have been observed, we hypothesize that localized intratumoral treatment with combination of ACT and Delta-24-RGDOX (third generation oncolytic adenovirus developed by our group) induces not only potent therapeutic effect in treated tumor but also abscopal benefit to eliminate distant disseminated tumors. Using a B16-C57BL/6 melanoma model with disseminated tumors in C57BL/6 mice, we found gp100-specific CD8+ T cells injected into the first subcutaneous (s.c.) tumor showed tropism for distant s.c. and intracranial tumors, tumor draining lymph nodes, compared to spleen, blood and normal brain hemisphere. In a B16-OVA-C57BL/6 s.c./s.c. tumor model, Delta-24-RGDOX injections following gp100-specific T cells in the first tumor increased total cytotoxic T cell presence within both tumors, including gp100- and OVA- specific T cells. Further analysis revealed that Delta-24-RGDOX reduced the exhaustion of OVA-specific T cells while that of gp100-specific T cells kept at a low level. Moreover, Delta-24-RGDOX augmented the activity of the splenocytes against the tumor cells and other tumor-associated antigens (OVA, TRP2) than gp100. Consequentially, the combination of OVA-specific T cells and Delta-24-RGDOX was more potent to inhibit the injected and untreated distant tumor growth and caused improved survival rate than either of the agent alone (p &lt; 0.05). Importantly, we observed relapse of the regressed tumors in the T cell treatment group, but not in the combination group. The survivors developed immune memory against rechallenging with B16-OVA cells. Collectively, our data demonstrate that localized treatment with intratumoral ACT followed by Delta-24-RGDOX induces global immune activation and antigen spread to expand antitumor T cell repertoire, leading to efficacious systemic anti-tumor immunity and sustainable tumor regression.

Telestration with augmented reality for visual presentation of intraoperative target structures in minimally invasive surgery: a randomized controlled study

AIMS

In minimally invasive surgery (MIS), intraoperative guidance has been limited to verbal communication without direct visual guidance. Communication issues and mistaken instructions in training procedures can hinder correct identification of anatomical structures on the MIS screen. The iSurgeon system was developed to provide visual guidance in the operating room by telestration with augmented reality (AR).

METHODS

Laparoscopic novices (n = 60) were randomized in two groups in a cross-over design: group 1 trained only with verbal guidance first and then with additional telestration with AR on the operative screen and vice versa for group 2. Training consisted of laparoscopic basic training and subsequently a specifically designed training course, including a porcine laparoscopic cholecystectomy (LC). Outcome included time needed for training, performance with Global Operative Assessment of Laparoscopic Skills (GOALS), and Objective Structured Assessment of Technical Skills (OSATS) score for LC, complications, and subjective workload (NASA-TLX questionnaire).

RESULTS

Telestration with AR led to significantly faster total training time (1163 ± 275 vs. 1658 ± 375 s, p < 0.001) and reduced error rates. LC on a porcine liver was performed significantly better (GOALS 21 ± 5 vs. 18 ± 4, p < 0.007 and OSATS 67 ± 11 vs. 61 ± 8, p < 0.015) and with less complications (13.3% vs. 40%, p < 0.020) with AR. Subjective workload and stress were significantly reduced during training with AR (33.6 ± 12.0 vs. 30.6 ± 12.9, p < 0.022).

CONCLUSION

Telestration with AR improves training success and safety in MIS. The next step will be the clinical application of telestration with AR and the development of a mobile version for remote guidance.

Accurate detection of tumor-specific gene fusions reveals strongly immunogenic personal neo-antigens

Cancer-associated gene fusions are a potential source for highly immunogenic neoantigens, but the lack of computational tools for accurate, sensitive identification of personal gene fusions has limited their targeting in personalized cancer immunotherapy. Here we present EasyFuse, a machine learning computational pipeline for detecting cancer-specific gene fusions in transcriptome data obtained from human cancer samples. EasyFuse predicts personal gene fusions with high precision and sensitivity, outperforming previously described tools. By testing immunogenicity with autologous blood lymphocytes from patients with cancer, we detected pre-established CD4⁺ and CD8⁺ T cell responses for 10 of 21 (48%) and for 1 of 30 (3%) identified gene fusions, respectively. The high frequency of T cell responses detected in patients with cancer supports the relevance of individual gene fusions as neoantigens that might be targeted in personalized immunotherapies, especially for tumors with low mutation burden.

Abstract 3559: Redirection of anti-virus immunity towards anti-tumor immunity using nanoparticle-induced immune tolerance for oncolytic adenovirus therapy

Recent clinical observations that some coronavirus infections induced complete remissions in lymphoma patients emphasized again the potential of cancer virotherapy. Infection of cancer cells with oncolytic viruses reshapes the tumor microenvironment by activating anti-viral and anti-tumor immunity. A phase 1 clinical trial using oncolytic adenovirus Delta-24-RGD (DNX-2401) to treat recurrent malignant gliomas demonstrated activation of CD8+ T-cells and significant clinical benefits for a subset of patients. However, both anti-virus and anti-tumor immune responses are contingent on the activation of respective clones of CD8+ T-cells, which compete for clonal expansion. Thus, overexpansion of T-cells against viral antigens reduces the frequency of subdominant clones against tumor antigens. We hypothesized that inducing immune tolerance for viral antigens will decrease anti-viral immunity and in turn derepress anti-tumor immunity, resulting in enhanced efficacy of cancer virotherapy. In this work, we used nanoparticles encapsulating adenoviral antigens E1A, E1B and hexon that distributed to liver resident macrophages (P&lt;0.0001) and induced peripheral immune tolerance. Functional experiments to restimulate immune cells with viral or tumor antigens showed that injection of nanoparticles induced virus-specific immune tolerance and redirected the focus of the immune response towards tumor peptides as measured by interferon-gamma secretion (P&lt;0.0001). Co-culture experiments also showed increased activation of immune cells against fixed tumor cells after nanoparticle treatment (P&lt;0.0001). Reduction of virus-specific T-cells and concurrent expansion of tumor-specific T-cell clones were further confirmed with E1A or OVA tetramers (P&lt;0.05). Flow cytometry analysis suggested increased anti-tumor responses were due to differences in T-cell clones and not due to other immune populations including natural killer cells or myeloid-derived suppressor cells (P=0.3). Importantly, virotherapy in combination with nanoparticle-induced immune tolerance towards viral antigens in tumor-bearing mice increased the overall survival and doubled the percentage of long-term survivors compared to virus treatment alone. Our data should propel the development of a future clinical trial aiming to maximize the potential of anti-tumor immunity during cancer virotherapies.

Citation Format: Dong Ho Shin, Hong Jiang, Debora Kim, Teresa T. Nguyen, Sagar Sohoni, Xuejun Fan, Yanhua Yi, Arie C. Van Wieren, Gheath Al-Atrash, Chantale Bernatchez, Ramon Alemany, Marta Alonso, Frederick Lang, Candelaria Gomez-Manzano, Bulent Ozpolat, Juan Fueyo. Redirection of anti-virus immunity towards anti-tumor immunity using nanoparticle-induced immune tolerance for oncolytic adenovirus therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3559.

Abstract 3329: Efficacy of EGFR/PI3K signaling inhibition is enhanced with LSD1 inhibition in glioblastoma stem cell (GSC) models

Mutated and dysregulated protein kinases, such as EGFR and PI3K, have become major targets in cancer therapy due to the growth advantage they confer and the frequency of alterations. In glioblastoma (GBM), EGFR and PI3K are two of the most mutated genes and result in hyperactivation of these kinases. However, single agent inhibition has offered minimal success, largely due to the development of resistance from compensatory downstream signaling pathways. One strategy to circumvent resistance and improve efficacy in GBM is to use combination therapy, such as concurrent inhibition of EGFR or PI3K with inhibition of relevant epigenetic modulators. In GBM, lysine-specific demethylase 1 (LSD1) is an important epigenetic regulator that has shown to promote kinase signaling in cancer models. Therefore, the present study sought to define the relationship between the EGFR/PI3K signaling pathway and LSD1 and to evaluate the efficacy of co-inhibition of EGFR/PI3K and LSD1 in GBM.Transcriptional changes were examined following knockdown of LSD1 in isogenic human GBM cells using RNA-seq. These data were analyzed by GSEA to evaluate biological processes associated with the LSD1 expression. We identified several kinase signaling processes that were enriched in GBM cells with wild type LSD1 such as gene sets for regulation of PI3K activity, RTK binding, and transmembrane RTK activity. The effect of kinase inhibition on LSD1 expression was assessed using western blot analysis. We also evaluated the effects of LSD1 inhibition on expression of downstream kinase signaling proteins. Three kinase inhibitors directed against either EGFR or PI3K were evaluated in GSCs as single agents and in combination with LSD1 inhibitors. The three kinase inhibitors, osimertinib, erlotinib, and BKM120, all have evidence of some brain penetrance. We also evaluated a novel dual kinase inhibitor, MTX-241, which targets both EGFR and PI3K simultaneously. Five LSD1 inhibitors were assessed for their ability to enhance efficacy of EGFR/PI3K inhibitors.Our results demonstrate that LSD1 protein expression can be modulated by stimulation of EGFR in patient-derived GSCs. We observed an increase in LSD1 protein expression following the addition of EGF in GSC 17 cells. The concurrent inhibition of EGFR/PI3K and LSD1 enhanced the in vitro efficacy compared to single agent, supporting convergence of kinase signaling and LSD1 dependent pathways. In fact, several treatment combinations of EGFR/PI3K inhibitors and LSD1 inhibitors resulted in synergistic effects in multiple GSC lines.In summary, our results highlight the need for effective therapy combinations that can reduce the population of GSCs and avoid the adaptive resistance that is typical of kinase inhibitors. Future studies will focus on evaluating the efficacy and tolerability of the most promising treatment combinations in vivo using orthotopic xenograft models of the GSCs.

Citation Format: Lea Stitzlein, Matthew Luetzen, Caitlin McCabe, Maninder Khosla, Melissa Singh, Xiaoping Su, Yue Lu, Joy Gumin, Frederick Lang, Christopher Whitehead, Judith Sebolt-Leopold, Joya Chandra. Efficacy of EGFR/PI3K signaling inhibition is enhanced with LSD1 inhibition in glioblastoma stem cell (GSC) models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3329.

AB1390 COMPLEMENTARY DIGITAL THERAPY SAFELY IMPROVES QUALITY OF LIFE IN PATIENTS WITH INFLAMMATORY ARTHRITIS

Background

Self-management strategies play a central role in improving clinical outcomes in patients with inflammatory arthritis. EULAR recently highlighted the essential role of digital health to increase the self-management of patients. Evidence regarding these supporting digital tools, including mobile apps, is currently however very limited [1].

Objectives

To evaluate the efficacy and safety of a mobile app (Mida Rheuma App) in patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA, including psoriatic arthritis [PsA]) in a prospective study.

Methods

Patients with RA, SpA/ PsA, stable on their antirheumatic therapy for ≥4 weeks, were eligible to use the Mida Rheuma App in addition to standard care treatment. The usage of the app targeted the optimization of non-medical treatment in a 4-step process: (1) collection of the information (HRQoL, disease activity, physical impairment, diet, mental health, physical activity, etc.) using standardized questionnaires via the conversational health coach Mida; (2) development of a patient profile that focuses on the patient’s disease, well-being, and behavior; (3) creation of a personalized, evidence-based disease management program based on recommendations from medical guidelines, medical standards, and state-of-the-art clinical research; (4) implementation of personalized recommendations into the patient’s daily life by providing short daily tasks that accelerate positive behavior change. Additionally, the health coach Mida supports the patient in coping with stress, sadness, depression, fatigue, and further disease-related symptoms. This is achieved by various cognitive behavioral techniques, meditation and relaxation methods.

Additionally, we assessed demographic parameters, treatment regimen, disease activity (e.g., SDAI, ASDAS), and other patient-reported outcomes (e.g., SF-36) at baseline and after 4 weeks. The study was approved by the Ethics Committee of the Medical Faculty of Mannheim, Heidelberg University.

Results

Of 20 patients screened after obtaining informed consent, 19 were enrolled in the study, and 17 patients (12 RA, SpA: 1 axSpA, 4 PsA) completed the study (2 drop-outs due to unwillingness to finish the study). 7 (41.2%) patients were male, and ages ranged from 19 to 63 (40.5±12.2) years). Patients were treated as follows: 7 NSAIDs (41.2%), 2 GC (>5 mg) (11.8%), 3 HCQ (17.6%), 10 MTX (58.8%), 1 LEF (5.9%), 1 SSZ (5.9%), 1 APR (5.9%), 3 JAKi (17.6%), 1 TNFi (5.9%), 2 IL-6i (11.8%), 1 IL-17i (5.9%). No significant change in antirheumatic treatment was observed during the study. At baseline, 29.4% of the RA and PsA patients were in remission, 25.2% had low, 29.4% had moderate, and none had high disease activity according to SDAI, one axSpA patient had low disease activity (ASDAS: 2.2). At the end of the study, slightly more RA and PsA patients were in remission and had low disease activity (58.8% and 23.5%, respectively) and less had moderate activity (11.8%); the axSpA patient had inactive disease (ASDAS: 1.8).

Regarding patient-reported outcomes, statistically significant improvement was noted for the following parameters: SF-36 Total Score (relation of CI 90% and minimum clinically important difference of 2.5), increase of Physical Component Summary of SF-36 by 23.6% (p=0.024), ‘role limitations due to physical health’ by 76.9% (p=0.022), and ‘general health’ - by 17.1% (p=0.048); and evidence of potential clinical importance of their dynamics for Patient Health Questionnaire (PHQ)-9, ‘emotional well-being’ and RADAI-5. No negative changes were observed for assessed parameters. No adverse events were reported throughout the study.

Conclusion

This prospective study suggests that using an app-based personalized disease management program significantly quickly improves several measures of patient-reported outcomes and disease activity in patients with RA and PsA/SpA. These findings highlight the potential of complementary digital therapy in patients with inflammatory arthritis.

References

[1]Knitza J. JMIR Mhealth Uhealth. 2019 Aug 5;7(8):e14991

Disclosure of Interests

Dmytro Fedkov Shareholder of: Midaia GmbH, Speakers bureau: Phizer, MSD, Consultant of: Janssen, Novartis, Andrea Berghofen: None declared, Christel Weiss: None declared, Christine Peine Shareholder of: Midaia GmbH, Felix Lang Shareholder of: Midaia GmbH, Johannes Knitza Consultant of: ABATON, Vila Health, Medac, Grant/research support from: ABATON, Jan Leipe: None declared

EPCO-19. SYSTEMS BIOLOGY APPROACH ON MGMT-METHYLATED, IDH WILD-TYPE SHORT-TERM SURVIVORS REVEALS MUTATIONS IN THE BRCA1-MEDIATED DNA REPAIR SIGNALING PATHWAY

Numerous multi-omic studies have revealed the vast molecular complexity of glioblastoma; however, these studies have failed to identify actionable drivers for definitive therapy. Unlike conventional relational data analysis methods used to examine such data, systems biology approaches using graph databases have emerged as powerful tools with flexibility and scalability needed to reveal specific vulnerabilities. Here we demonstrate the utility of a patient-centric graph database in identifying novel factors associated with poor outcome (survival &lt; 8 months) in patients with MGMT promoter methylated glioblastoma. Using a cohort of 112 patients from the TCGA database, we integrated high-impact mutations with MGMT methylation status. Network analysis revealed three subnetworks, consisting of (a) methylated patients, the M-network, (b) methylated and unmethylated patients, the MU-network, and (c) unmethylated patients, the U-network. In addition, querying the genes in the M-network revealed three key molecules in the DNA repair pathway, namely, FANC-A, FANC-E, and MYUTH, mutated in five patients (q-value &lt; 2.3E-02). Moreover, we observed that BRCA1 mediates other critical signaling molecules in the MU-network. Interestingly, in intermediate (8-24 months) or long-term ( &gt;24 months) survivors networks, this pathway is not implicated. In light of recent studies implicating BRCA1 modulating temozolomide resistance in GBM sphere-forming cells and BRCA1’s protein expression predicting survival in patients, this result suggests that mutations in BRCA1-mediated DNA repair pathways hinder response to chemotherapy despite methylated MGMT, reducing the survival in patients. Besides this novel result explaining low survival in MGMT methylated patients through a synthesis of epigenetic and genetic data, our framework provides a novel and compelling paradigm for data integration at various scales from molecular events in a single patient’s tumor to integrating the molecular profile (or genotype) with phenotypic characteristics at the population level. We will present additional insights derived from this analysis at the SNO annual meeting.

IMMU-43. IMMUNE CONTEXTURE OF ISOCITRATE DEHYDROGENASE STRATIFIED HUMAN GLIOMAS REVEALED BY SINGLE-CELL TRANSCRIPTOMICS AND ACCESSIBLE CHROMATIN

The immune cell composition of isocitrate dehydrogenase wild type (IDH-wt) glioma patients significantly differs compared to IDH-mutant (IDH-mut) yet a detailed and unbiased understanding of their transcriptomic and epigenetic landscapes remains elusive. To this end, we performed single-cell RNA-sequencing (scRNA-seq) and single-cell Assay for Transposase-Accessible Chromatin using sequencing (sc-ATAC-seq) on ~100,000 tumor-associated immune cells from seventeen IDH mutation classified primary and recurrent human gliomas and non-glioma brains (NGBs). Our analyses revealed sixty-two transcriptionally distinct myeloid and lymphoid cell states within and across glioma subtypes and we noted microglial attrition with increasing disease severity concomitant with invading monocyte-derived cells (MDCs) and lymphocytes. Specifically, certain microglial and monocyte-derived subpopulations were associated with antigen presentation gene modules, akin to cross-presenting dendritic cells. As tissue macrophages exhibit multifaceted polarization in response to microenvironmental cues, we clarify the existence of microglia/macrophage functional states beyond M1/M2 paradigms exemplified by the presence of palmitic-, oleic- acid, and glucocorticoid responsive polarized states. We identified cytotoxic T cells with poly-functional cytolytic states mostly in recurrent IDH-wt gliomas. Furthermore, ligand-receptor interactome analyses showed a preponderance of antigen presentation/phagocytosis over the checkpoint axis in IDH-wt compared to IDH-mut gliomas. Additionally, our sc-ATAC-seq analyses revealed differences in regulatory networks in NGBs, IDH-mut, and IDH-wt glioma-associated immune cells. In particular, we noted reduced microglial usage of an iron recycling SPIC transcription factor and Interferon Regulatory Factors (IRFs); IRF1 and IRF2 in IDH-wt relative to IDH-mut and NGBs. Unique features such as amplification of 11-Zinc Finger Protein accessibility were restricted to MDCs. Finally, sc-ATAC-seq profiles of CD8+ exhausted T cells from IDH-wt showed strong enhancer accessibility on CTLA-4, Layilin, and TIM-3 but no enrichment on PD1 was seen. In summary, our study provides unprecedented granular detail of transcriptionally and epigenomically defined glioma-specific immune contexture that can be exploited for immunotherapy applications.

610 Sustainable regression of disseminated solid tumors mediated by in situ combinational treatment with adoptive T cell therapy and oncolytic adenovirus Delta-24-RGDOX

Background

Unlike its remarkable success in treating hematological malignancies, adoptive T cell therapy (ACT), such as CAR T therapy, targeting limited tumor-associated antigens (TAAs) is far less effective in patients with heterogeneous solid tumors. Oncolytic viruses, including oncolytic adenovirus Delta-24-RGDOX from our group [1, 2], are emerging as promising immunotherapy drugs. To take advantage of instant antitumor activity of T cells and oncolytic adenovirus mediated in situ autovaccination against heterogeneous cancer cells, we hypothesize that intratumorally injected Delta-24-RGDOX complements with ACT to overcome antigen escape, leading to more sustainable anti-cancer effect.

Methods

We used B16-OVA-C57BL/6 subcutaneous (s.c.)/s.c. melanoma model [2] to assess the systemic therapeutic effect in disseminated tumors. OVA (or gp100)-specific CD8+ T cells were injected into the first tumor, followed by three injections of Delta-24-RGDOX into the same tumor. T cells from the mice were profiled for surface markers with flow cytometry. Activity of splenocytes against tumor cells and specific TAAs was measured with ELISA. Tumor growth was monitored through measuring tumor size three times a week. The animal survival curves were plotted according to the Kaplan–Meier method.

Results

TAA-specific T cells injected into the first s.c. tumor showed tropism for disseminated s.c. and intracranial tumors, tumor draining lymph nodes, compared to normal tissue, spleen and peripheral blood. Delta-24-RGDOX increased total T cell presence within the tumors, and the activity of the T cells against the tumor cells and targeting other antigens than the one targeted by the transferred T cells. Consequentially, the combination of OVA-specific T cells and Delta-24-RGDOX was more potent to inhibit the injected first tumor and untreated disseminated second tumor growth and resulted in improved survival rate than either of the agent alone (p < 0.05). Interestingly, we observed relapse of the regressed tumors in the group treated by T cells alone. But the relapse was not observed in most of the mice in the combination group. The survivors from the combination therapy were protected from rechallenging with B16-OVA cells but not lung carcinoma cells, suggesting the development of immune memory.

Conclusions

Delta-24-RGDOX collaborates with ACT to induce more potent systemic immunity against the tumors, leading to sustainable tumor regression and improved survival rate. Our study indicates the virus induces antigen spread, resulting in expansion of T cell repertoire to prevent cancer relapse in ACT.

References

Jiang, H., et al., Localized Treatment with Oncolytic Adenovirus Delta-24-RGDOX Induces Systemic Immunity against Disseminated Subcutaneous and Intracranial Melanomas. Clin Cancer Res, 2019. 25(22): p. 6801–6814. https://cancerres.aacrjournals.org/content/77/14/3894.long.

Jiang, H., et al., Oncolytic Adenovirus and Tumor-Targeting Immune Modulatory Therapy Improve Autologous Cancer Vaccination. Cancer Res, 2017. 77(14): p. 3894–3907.https://clincancerres.aacrjournals.org/content/25/22/6801.full-text.pdf

Abstract 1785: Inhibition of the IDO-Kyn-AhR cascade optimizes virotherapy in glioblastoma and depends on CD4 T-cell activation

Immune enhancement of virotherapy by reshaping the tumor immune landscape may improve its success rates. IDO, an IFNγ inducible tryptophan catabolizing enzyme, is upregulated in glioblastoma, correlating with poor prognoses. IDO-mediated tryptophan depletion in the tumor-microenvironment decreases viral replication and diminishes cell proliferation and induces apoptosis of surrounding effector T-cells. Furthermore, kynurenine (kyn), a metabolite of tryptophan, induces T-cell differentiation into Tregs. Excess kynurenine also elicits AhR-mediated lymphocyte dysfunction and immunosuppression. The immune stimulating effect of oncolytic-virus, D24-RGDOX, clinically known as DNX-2440, triggers IFNγ production contributing to a positive IDO-Kyn-AhR feedback loop. Thus, we hypothesized that combining D24-RGDOX with IDO inhibitors will synergize to treat glioblastoma. We studied the IDO-Kyn-AhR cascade in response to D24-RGDOX infection in human and murine glioblastoma cells. Orthotopic syngeneic glioblastoma mouse models were used to determine efficacy and tumor immune effects of D24-RGDOX and IDO inhibitors as single agents or as a combination treatment. We characterized IDO and AhR in D24-RGDOX infected cancers using immunofluorescence, qRT-PCR, and flow cytometry and found increased expression of both proteins in vitro and in vivo compared to mock infected controls. D24-RGDOX also increased activity of AhR in cancer cells as indicated by an AhR responsive elements transcription assay. Furthermore, we showed that viral protein expression and viral activity was enhanced in D24-RGDOX infected cultures under IDO inhibition. To test the therapeutic efficacy of combining D24-RGDOX with IDO inhibitors, we used a murine immunocompetent glioblastoma model; the combination produced 30% more long-term survivors compared D24-RGDOX alone (P=0.03, log-rank test). Next, lymphocytic depletion studies illustrated that this anticancer effect was dependent on CD4+ T-cell activation. We observed 100% survival in the re-challenged long-term glioblastoma survivors, indicating the establishment of immune memory by the combination. Functional studies showed significant increases in anti-tumor activity of splenocytes from combination-treated mice compared to D24-RGDOX-treated mice (P=0.009, student t-test). Flow cytometry studies revealed that combination-treated mice yielded the highest levels of chronically activated T-cells and lowest levels of Tregs and MDSCs compared to D24-RGDOX alone (P≤0.05 in all populations, student t-test). This microenvironment remodeling correlated with complete tumor elimination. Altogether, D24-RGDOX activates the IDO-Kyn-AhR cascade in gliomas, identifying new targets, which when inhibited have the potential to enhance the anti-glioma effect of oncolytic-viruses by reversing tumor immunosuppression.

Citation Format: Teresa T. Nguyen, Dong Ho Shin, Hong Jiang, Derek A. Wainwright, Sagar Sohoni, Sumit Gupta, Ashley Ossimetha, Frederick Lang, Marta Alonso, Candelaria Gomez-Manzano, Juan Fueyo. Inhibition of the IDO-Kyn-AhR cascade optimizes virotherapy in glioblastoma and depends on CD4 T-cell activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1785.

Abstract 3053: Armed oncolytic virus for treatment of pediatric diffuse intrinsic pontine glioma

Diffuse Intrinsic Pontine Glioma (DIPG) is the leading cause of pediatric death by brain tumors with a median survival of only 9 months, in spite of the current standard of therapy which includes radiation. The purpose of our study is to explore the use of oncolytic adenoviruses as a new therapeutic modality. Our group is leading a phase I clinical trial in naive DIPGs treated with the oncolytic adenovirus Delta-24-RGD, also named DNX-2401 (NCT03178032), which results are still pending. Of interest, clinical trials using Delta-24-RGD in adult gliomas resulted in encouraging results with long-term survivors and the presence of a strong anti-tumor immunity. In this study, we aim to test the effect of armed Delta-24-RGD with immune costimulatory ligands such as GITRL (Delta-24-GREAT) and OX-40L (Delta-24-RGDOX or DNX-2440) for the treatment of DIPGs. We used a panel of murine DIPG cell lines (NP53 and XFMA) to test the effect of these armed-oncolytic adenoviruses. Infectivity assay using an Ad-RGD-GFP vector and flow cytometry showed the expression of the ectopic GFP in more than 80% of the NP53 cells (50 MOIs) and XFMA cells (30 MOIs). Consistent results were obtained using flow cytometry and western blot to detect the expression of the ectopic ligands GITRL and OX-40L in these cultures. These cells were semipermissive for viral replication as assessed by the detection of the viral structural protein hexon in western blot analysis. Preliminary in vivo data using immunocompetent mice models where DIPG cells have been implanted into the pons showed a dose-dependent effect and the generation of immune memory. Our results suggest that oncolytic adenoviruses expressing positive immunocheckpoints might prove be a new effective modality for treating DIPG and hence, increase survival in children suffering this dismal disease.

Citation Format: Sumit Gupta, Virginia Laspidea, Juan Fueyo, Oren Becher, Teresa Nguyen, Dong Ho Shin, Hong Jiang, Sagar Sohoni, Xuejun Fan, Yanhua Yi, Joy Gumin, Frederick Lang, Candelaria Gomez-Manzano, Marta M. Alonso. Armed oncolytic virus for treatment of pediatric diffuse intrinsic pontine glioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3053.

Current strategies to circumvent the antiviral immunity to optimize cancer virotherapy

Cancer virotherapy is a paradigm-shifting treatment modality based on virus-mediated oncolysis and subsequent antitumor immune responses. Clinical trials of currently available virotherapies showed that robust antitumor immunity characterizes the remarkable and long-term responses observed in a subset of patients. These data suggest that future therapies should incorporate strategies to maximize the immunotherapeutic potential of oncolytic viruses. In this review, we highlight the recent evidence that the antiviral immunity of the patients may limit the immunotherapeutic potential of oncolytic viruses and summarize the most relevant approaches to strategically redirect the immune response away from the viruses and toward tumors to heighten the clinical impact of viro-immunotherapy platforms.

Robotic-assisted cholecystectomy is superior to laparoscopic cholecystectomy in the initial training for surgical novices in an ex vivo porcine model: a randomized crossover study

Background

Robotic-assisted surgery (RAS) potentially reduces workload and shortens the surgical learning curve compared to conventional laparoscopy (CL). The present study aimed to compare robotic-assisted cholecystectomy (RAC) to laparoscopic cholecystectomy (LC) in the initial learning phase for novices.

Methods

In a randomized crossover study, medical students (n = 40) in their clinical years performed both LC and RAC on a cadaveric porcine model. After standardized instructions and basic skill training, group 1 started with RAC and then performed LC, while group 2 started with LC and then performed RAC. The primary endpoint was surgical performance measured with Objective Structured Assessment of Technical Skills (OSATS) score, secondary endpoints included operating time, complications (liver damage, gallbladder perforations, vessel damage), force applied to tissue, and subjective workload assessment.

Results

Surgical performance was better for RAC than for LC for total OSATS (RAC = 77.4 ± 7.9 vs. LC = 73.8 ± 9.4; p = 0.025, global OSATS (RAC = 27.2 ± 1.0 vs. LC = 26.5 ± 1.6; p = 0.012, and task specific OSATS score (RAC = 50.5 ± 7.5 vs. LC = 47.1 ± 8.5; p = 0.037). There were less complications with RAC than with LC (10 (25.6%) vs. 26 (65.0%), p = 0.006) but no difference in operating times (RAC = 77.0 ± 15.3 vs. LC = 75.5 ± 15.3 min; p = 0.517). Force applied to tissue was similar. Students found RAC less physical demanding and less frustrating than LC.

Conclusions

Novices performed their first cholecystectomies with better performance and less complications with RAS than with CL, while operating time showed no differences. Students perceived less subjective workload for RAS than for CL. Unlike our expectations, the lack of haptic feedback on the robotic system did not lead to higher force application during RAC than LC and did not increase tissue damage. These results show potential advantages for RAS over CL for surgical novices while performing their first RAC and LC using an ex vivo cadaveric porcine model.

Registration number

researchregistry6029

Graphic abstract

TAMI-24. BEHAVIOR OF GLIOBLASTOMA STEM-LIKE CELLS WITH KNOWN IDH1 STATUS IN CEREBRAL ORGANOIDS

Glioblastomas (GBM) exhibit high proliferative index, areas of necrosis, high vascularization, and are highly invasive to normal brain tissues. The most common and lethal form of GBMs are primary GBMs, with no prior clinical history. Whereas, secondary GBMs arise from low-grade gliomas and are associated with IDH1 mutation. Pre-clinical studies of GBM largely depend on patient-derived GBM stem-like cells (GSCs) in vitro and in vivo as orthotopic xenografts. Cerebral organoids (COs) derived from induced pluripotent stem cells can serve as allogenic in vitro model systems to study interactions between normal brain and GSCs. COs have been shown to harbor neural stem cells and their differentiated progenies as well as microglia within distinct niches. Here, we co-cultured 45 day-old COs and MDA-GSCs lines representing mesenchymal sub-group (M-MDA-GSC), classical sub-group (C-MDA-GSC), and IDH1 mutant (IDH1R132H-MDA-GSC). MDA-GSCs stably express fluorescent proteins and is used to track GSCs within COs. These GSC bearing COs were fixed, embedded, sectioned, immuno-stained, and imaged by confocal microscope. There was a positive correlation between GSC numbers in allografted niche and invasion into COs as measured from the edge of organoid, M-MDA-GSC (R2=0.99; 0.89μm/cell), C-MDA-GSC (R2=0.92; 0.66μm/cell), and IDH1R132H-MDA-GSC (R2=0.89; 0.5μm/cell). Additionally, M-MDA-GSCs had significantly high percentage of Ki67+ve invasive cells (24%) in comparison to C-MDA-GSCs (5.1%; p=0.0057). As a measure of interaction of MDA-GSC with normal cells, we assessed proximity of IBA1+ve microglia in GSC niche within organoids and show that M-MDA-GSC and IDH1R132H-MDA-GSC highly co-localized with IBA1+ve microglia on day12 of co-culture. In conclusion, our cerebral organoid-based allograft study shows that mesenchymal GSCs (M-MDA-GSC) are most invasive whereas IDH1 mutant GSCs (IDH1R132H-MDA-GSC) are least invasive. C-MDA-GSCs are least proliferative while invading into normal COs. Uniqueness of CO based allograft system is highlighted by observed similarity between M-MDA-GSC and IDH1R132H-MDA-GSC for their potential to attract IBA1+ve microglia.

TMOD-16. A NOVEL ADENOVIRAL-PERMISSIVE, IMMUNOCOMPETENT HAMSTER GLIOMA MODEL TO EVALUATE ONCOLYTIC ADENOVIRAL THERAPY

Oncolytic adenoviruses, including Delta-24-RGD, target tumors by direct tumor cell oncolysis and by activation of an anti-tumor immune response. Due to the species selectivity of oncolytic adenoviruses, there is currently no single preclinical animal model of glioma that supports viral replication, tumor oncolysis, and virus-mediated immune responses. To address this gap, we took advantage of the Syrian hamster to develop the first glioma model that is both adenovirus replication-permissive and immunocompetent. Hamster glioma stem-like cells (GSCs), transformed by forced expression of hTERT, SV40 large T antigen, and h-RasV12, reproducibly form intracranial tumors in hamsters. In vitro, electron microscopy and cytopathic effect assays demonstrated that hamster GSCs supported viral replication and were susceptible to Delta-24-RGD-mediated cell death. In vivo, hamster GSCs consistently developed into highly proliferative tumors resembling high-grade gliomas. Following intratumoral delivery of Delta-24-RGD, immunohistochemistry for viral proteins demonstrated viral infectivity and replication in hamster gliomas. Flow cytometry revealed increased T cell infiltration in Delta-24-RGD-infected tumors. Delta-24-RGD treatment of tumor-bearing hamsters led to significantly increased survival compared with hamsters treated with PBS. Using this model, we evaluated the effects of corticosteroid-mediated immunosuppression on Delta-24-RGD efficacy. Dexamethasone treatment significantly decreased peripheral blood lymphocytes, decreased tumor-infiltrating lymphocytes, and suppressed the levels of serum anti-adenovirus antibodies. Dexamethasone reduced the number of long-term survivors and decreased the median survival (50 days for Delta-24-RGD + dexamethasone vs undetermined for Delta-24-RGD alone). In summary, we have developed the first adenovirus-permissive, immunocompetent hamster glioma model, addressing a critical need for a model in which to study the role of direct oncolysis in driving immune mediated viral clearance versus driving an antiglioma immune response. Understanding these mechanisms is critical to optimizing the success of oncolytic adenoviral therapy in the clinic.

EPCO-11. IN VIVO FUNCTIONAL GENOMIC SCREEN IDENTIFIES WISP1 AS AN OVEREXPRESSED DRIVER OF GLIOBLASTOMA

There is a tremendous need to identify new genetic drivers of glioblastoma which can serve as potential therapeutic targets. In order to find new drivers, we leveraged genomic datasets to conduct a context specific in vivo functional genomic screen of overexpressed and/or amplified genes in GBM. We identified WISP1, a secreted extracellular matrix protein, to be an overexpressed driver in GBM. Overexpression of WISP1 was able to drive tumor growth in various in vivo models. Knockdown of WISP1 with shRNAs resulted in reduced colony formation in vitro and reduced tumor growth in vivo. Rescue experiments validated that the shRNAs were on target. Functional characterization of the protein revealed that the TSP module is necessary for the phenotype. Intriguingly, overexpression of WISP1 lacking the signal peptide module for secretion resulted in a strong phenotype. Co-culture and conditioned medium experiments further supported a secretion independent intracellular role of WISP1 in GBM. Though WISP1 is a secreted protein we have found some basal localization in the cytosol. Overall, we have revealed WISP1 to be a driver of GBM with possible therapeutic potential as a target. This study has expanded our understanding of WISP1 by supporting a new role as a driver in GBM which can function in a non-canonical manner in the cytosol. Overall, we have revealed WISP1 to be a driver of GBM with possible therapeutic potential as a target.

EXTH-45. DELTA-24-RGDOX ACTIVATION OF THE IDO-KYN-AHR CASCADE IN GLIOBLASTOMA: OLD TARGETS FOR A NEW THERAPY

Immune enhancement of virotherapy by reshaping the tumor immune landscape may improve its success rates. IDO, an IFNγ inducible tryptophan catabolizing enzyme, is upregulated in glioblastoma, correlating with poor prognoses. IDO-mediated tryptophan depletion in the tumor-microenvironment decreases proliferation and induces apoptosis of surrounding effector T-cells. Kynurenine, a metabolite of tryptophan, induces T-cell differentiation into immunosuppressive Tregs. Excess kynurenine elicits AhR-mediated lymphocyte dysfunction and immunosuppression. The immune stimulating effect of oncolytic-virus, Delta-24-RGDOX, triggers IFNγ production contributing to a positive IDO-Kynurenine-AhR feedback loop. We hypothesized that combining Delta-24-RGDOX with IDO inhibitors will synergize to effectively treat glioblastoma. We characterized IDO and AhR in Delta-24-RGDOX infected cancers using immunofluorescence, qRT-PCR, and flow cytometry and found increased expression of both proteins in vitro and in vivo. We also observed induction of AhR in CD4+ and CD8+ T-cells by Delta-24-RGDOX in vivo. Delta-24-RGDOX also increased activity of AhR in cancer cells as indicated by an AhR responsive elements transcription assay. We used a murine glioblastoma model to test the efficacy of combining Delta-24-RGDOX with IDO inhibitor, 1MT/indoximod; the combination produced 30% more long-term survivors compared Delta-24-RGDOX alone (P=0.03), which we showed, through lymphocytic depletion studies, was dependent on CD4+ T-cell activation. We observed 100% survival in the re-challenged long-term glioblastoma survivors, indicating the establishment of immune memory by the combination. Functional studies showed significant increases in anti-tumor activity of splenocytes from combination-treated mice compared to Delta-24-RGDOX-treated mice (P=0.009). Flow cytometry studies revealed that combination-treated mice yielded the highest levels of chronically activated T-cells and lowest levels of Tregs and myeloid derived suppressor cells compared to Delta-24-RGDOX single treatment (P≤0.05). This microenvironment remodeling correlated with complete tumor elimination. Altogether, Delta-24-RGDOX activates the IDO-Kyn-AhR cascade in gliomas, identifying new targets, which when inhibited have the potential to enhance the anti-glioma effect of oncolytic-viruses by reversing tumor immunosuppression.

EXTH-18. ENGINEERED EXOSOMES AS GENE DELIVERY TOOLS FOR THE TREATMENT OF GLIOBLASTOMA

Although we previously showed that exosomes are capable of delivering anti-glioma microRNAs (miRs) to brain tumors (Lang et al. 2018), our studies revealed significant opportunity to 1) improve packaging and delivery efficiency of exosomes and 2) expand the repertoire of anti-glioma miRs. We hypothesized that incorporation of viral proteins into exosomes would enhance miR packaging and cell entry. To test this hypothesis, we engineered exosomes that express retroviral Gag and VSVg proteins (eExos). Specifically, HEK293T cells were transfected with Gag, VSVg, and with Cre-recombinase containing plasmid (pCre) to generate eExos-pCre. After 48hrs eExos-pCre were isolated by differential ultracentrifugation. Western analyses verified Gag and VSVg in eExos-pCre, and PCR documented pCre in these exosomes. Next, U87 cells harboring a dsRed-eGFP-loxP reporter-gene were treated with eExos-pCre or control exosomes. Flow cytometry demonstrated that eExos-pCre resulted in 82% conversion of red cells to green, compared with controls (2% conversion), verifying the effectiveness of eExos to deliver plasmids containing anti-glioma agents. To identify effective anti-glioma miRs, we conducted a high-throughput screen of 539 miRs against 7 glioma stem cell lines (GSCs) and identified miR-124-2, miR-135-a-2, and Let7i as the most potent anti-glioma miRs. We then studied the ability of eExos to package and deliver plasmids of these miRs either singly (eExos-miR-124, eExos-miR-135, eExos-miRLet7i) or as a tri-cistronic plasmid (eExos-miR-124-135-Let7i). Although eExos-miR-124, eExos-miR-135, and eExos-miRLet7i significantly decreased in vitro proliferation in all three GSCs (p&lt; 0.01), eExos-miR-124-135-Let7i were most effective (p&lt; 0.001). In in vivo studies, mice harboring GSC231 gliomas were injected with each of the eExos-miRs. Most significant improvement in survival was seen with eExos-miR-124-135-Let7i (median 75 versus 32.5 days for controls, p&lt; 0.001). We conclude that eExos are a novel delivery strategy for human gliomas and that a tri-cistronic plasmid of miR-124-135-Let7i is highly effective against GBM and worthy of clinical translation.

EXTH-75. IN VITRO AND IN VIVO EFFICACY OF COMBINATORIAL INHIBITION OF LSD1 AND HDACS IN PATIENT DERIVED GLIOBLASTOMA STEM CELL MODELS

Inhibitors of histone deacetylases (HDACi) have been tested in glioblastoma (GBM), however, single agent clinical efficacy has not been proven, prompting study of combinatorial approaches. A rational HDACi combination strategy is with inhibition of LSD1, lysine specific demethylase 1, a histone demethylase known to exist in complex with HDAC1/2. We previously showed in vivo efficacy of combining a brain permeant LSD1 inhibitor, tranylcypromine (TCP) together with vorinostat. More selective inhibitors of LSD1 have been developed and were tested in the current study together with the HDACi, vorinostat or panobinostat in a panel of patient derived glioblastoma stem cell (GSC) lines that have been characterized as radio-resistant or radiosensitive. To test in vitro sensitivity, dose response experiments were conducted in nine GSC cell lines using three LSD1 inhibitors or two HDACi as single agents or in combination. Two non-tumor lines were also tested to assess selective cytotoxicity for brain tumor lines. Cell viability and clonogenicity assays were performed. Several radio-resistant GSC lines showed sensitivity to single agent LSD1 inhibitors, whereas some radio-sensitive GSCs did not, indicating distinct molecular mechanisms of response. Intracranial orthotopic xenograft models were used to test in vivo efficacy using the radioresistant GSC20 line. Interestingly, LSD1 inhibition alone promoted tumor burden reduction and better survival rates than combination treatment. RNA-Seq guided biomarkers of sensitivity to the LSD1/HDAC inhibitor combination were assessed in vitro and in vivo. Both in vivo and in vitro data show that GSC20 treated with GSK LSD1 inhibitor had higher levels of HKDC1 gene with in vivo data also showing elevated levels of FTH1. In vivo mouse data for vorinostat and combination treatment groups showed that only the FTH1 gene level was elevated, providing a potential explanation for low in vivo efficacy. Collectively, our data suggests that LSD1 inhibition represents a viable strategy in GBM.

RBIO-06. IMPLEMENTATION OF HUMAN INDUCED PLURIPOTENT STEM CELL DERIVED CEREBRAL ORGANOIDS TO MODEL NORMAL TISSUE RADIORESPONSE

Treatment-related sequelae following cranial irradiation have life changing impacts for patients and their caregivers. Characterization of the basic response of human brain tissue to irradiation has been difficult due to a lack of preclinical models. The direct study of human brain tissue in vitro is becoming possible due to advances in stem cell biology, neuroscience, and tissue engineering with the development of organoids as novel model systems which enable experimentation with human tissue models. We sought to establish a cerebral organoid (CO) model to study the radioresponse of normal human brain tissue. COs were grown using human induced pluripotent stem cells and a modified Lancaster protocol. Compositional analysis during development of the COs showed expected populations of neurons and glia. We confirmed a population of microglia-like cells within the model positive for the makers Iba1 and CD68. After 2-months of maturation, COs were irradiated to 0, 10, and 20 Gy using a Shepard Mark-II Cs-137 irradiator and returned to culture. Subsets of COs were prepared for immunostaining at 30- and 70-days post-irradiation. To examine the effect of irradiation on the neural stem cell (NSC) population, sections were stained for SOX2 and Ki-67 expression denoting NSCs and proliferation respectively. Slides were imaged and scored using the CellProfiler software package. The percentage of proliferating NSCs 30-days post-irradiation was found to be significantly reduced for irradiated COs (5.7% (P=0.007) and 3.4% (P=0.001) for 10 and 20 Gy respectively) compared to control (12.7%). The reduction in the proliferating NSC population subsequently translated to a reduced population of NeuN-labeled mature neurons 70 days post-irradiation. The loss of proliferating NSCs and subsequent reduction in mature neurons demonstrates the long-term effects of radiation. Our initial results indicate COs will be a valuable model to study the effects of radiation therapy on normal and diseased human tissue.

IMMU-35. TRANSCRIPTIONALLY DEFINED IMMUNE CONTEXTURE IN HUMAN GLIOMAS AT SINGLE-CELL RESOLUTION

The brain tumor immune microenvironment (TIME) continuously evolves during glioma progression and a comprehensive understanding of the glioma-centric immune cell repertoire beyond a priori cell types and/or states is uncharted. Consequently, we performed single-cell RNA-sequencing on ~123,000 tumor-derived immune cells from 17-pathologically stratified, IDH (isocitrate dehydrogenase)-differential primary, recurrent human gliomas, and non-glioma brains. Our analysis delineated predominant 34-myeloid cell clusters (~75%) over 28-lymphoid cell clusters (~25%) reflecting enormous heterogeneity within and across gliomas. The glioma immune diversity spanned functionally imprinted phagocytic, antigen-presenting, hypoxia, angiogenesis and, tumoricidal myeloid to classical cytotoxic lymphoid subpopulations. Specifically, IDH-mutant gliomas were enriched for brain-resident microglial subpopulations in contrast to enhanced bone barrow-derived infiltrates in IDH-wild type, especially in a recurrent setting. Microglia attrition in IDH-wild type -primary and -recurrent gliomas were concomitant with invading monocyte-derived cells with semblance to dendritic cell and macrophage/microglia like transcriptomic features. Additionally, microglial functional diversification was noted with disease severity and mostly converged to inflammatory states in IDH-wild type recurrent gliomas. Beyond dendritic cells, multiple antigen-presenting cellular states expanded with glioma severity especially in IDH-wild type primary and recurrent- gliomas. Furthermore, we noted differential microglia and dendritic cell inherent antigen presentation axis viz, osteopontin, and classical HLAs in IDH subtypes and, glioma-wide non-PD1 checkpoints associations in T cells like Galectin9 and Tim-3. As a general utility, our immune cell deconvolution approach with single-cell-matched bulk RNA sequencing data faithfully resolved 58-cell states which provides glioma specific immune reference for digital cytometry application to genomics datasets. Resultantly, we identified prognosticator immune cell-signatures from TCGA cohorts as one of many potential immune responsiveness applications of the curated signatures for basic and translational immune-genomics efforts. Thus, we not only provide an unprecedented insight of glioma TIME but also present an immune data resource that can be exploited to guide pragmatic glioma immunotherapy designs.

Annexin A7 is a critical regulator of Ca2+ mobilization and lipid metabolism during platelet activation and arterial thrombosis

Background

Platelet activation after contact to subendothelial collagen following atherosclerotic plaque rupture can lead to arterial thrombosis with acute thrombotic vascular occlusion. Annexin A7 (AnxA7) is an intracellular Ca2+- and phospholipid-binding protein that participates in the regulation of prostaglandin production in inflammatory diseases, but also in cell survival and tumor growth.

Objective

In the present study, we aimed to determine the role of AnxA7 for platelet Ca2+ signaling and lipid metabolism in platelet activation and arterial thrombosis in gene-targeted mice lacking annexin A7 (Anxa7−/−).

Results

AnxA7 is strongly expressed in platelets of platelet-rich human coronary thrombi aspirated from patients with acute ST elevation myocardial infarction. Functionally, platelet aggregation and dense granule secretion were significantly abrogated in Anxa7−/− platelets as compared to wildtype platelets (Anxa7+/+) after activation with collagen or collagen-related peptide (CRP), a specific agonist of the major platelet collagen receptor glycoprotein VI (GPVI). Further, in vitro thrombus formation on a collagen-coated surface under high arterial shear rates was significantly diminished in Anxa7-deficient platelets, and thrombotic vascular occlusion after FeCl3-induced injury in vivo was blunted in Anxa7−/−bone marrow chimeric mice, but no prolongation of bleeding time was observed. Moreover, Anxa7−/− platelets showed a significant reduction of IP3 production due to an abolished phospholipase C (PLC) gamma2 phosphorylation resulting in an abolished increase of [Ca2+]i after platelet activation with CRP.

Moreover, we could show by quantitative lipidomics analysis that annexin A7 critically affects platelet oxylipid metabolism following activation of GPVI-dependent platelet signalling since Anxa7−/− platelets showed a significant reduction of the bioactive metabolites thromboxane A2 and 12(S)-hydroxy-eicosatetraenoic acid (12(S)-HETE) levels as well as significantly reduced levels of several other prostaglandins following stimulation with collagen or CRP. Finally, defective PLCgamma2 phosphorylation, IP1 production and blunted increase of [Ca2+]i in Anxa7−/− platelets could be rescued by exogenous addition of 12(S)-HETE indicating that AnxA7 is a critical regulator of the platelet oxygenase 12-lipoxygenase (12-LOX) in GPVI-dependent platelet Ca2+ signalling during arterial thrombosis following activation by collagen.

Conclusions

The present study reveals annexin A7 as a critical regulator of oxylipid metabolism and Ca2+ signaling in GPVI-dependent platelet activation. Anxa7-deficiency further results in decreased in vitro and in vivo thrombus formation, but does not affect bleeding time.

In conclusion, annexin A7 plays an important role in platelet signaling during arterial thrombosis and thus, may reflect a promising target for novel antiplatelet strategies.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): German Research Foundation (Deutsche Forschungsgemeinschaft, DFG)

["Online from tomorrow on please": comparison of digital framework conditions of curricular teaching at national university ENT clinics in times of COVID-19 : Digital teaching at national university ENT clinics]

Hintergrund

Die Corona-Krise beeinflusst nicht nur das professionelle Handeln, sondern auch die Lehre an den Universitäten. Schlagworte wie „E-Learning“ und „Digitalisierung“ suggerieren die Möglichkeit innovativer, ad hoc verfügbarer Lösungsansätze für die Lehre in der aktuellen COVID-19-Situation. Die aktuelle Umstellung auf digitale Lehre ist aber nicht primär durch eine didaktische Sinnhaftigkeit oder institutionelle Strategie, sondern durch äußere Notwendigkeit geprägt.

Ziel der Arbeit

Ziel der Arbeit war die Erfassung der Lehrsituation an nationalen Universitäts-HNO-Kliniken und akademischen Lehrkrankenhäusern zu Beginn des virtuellen Corona-Sommersemesters 2020.

Material und Methode

Ein eigens erstellter Fragebogen zur jeweiligen lokalen Situation, den örtlichen Rahmenbedingungen sowie zu bundesweiten Szenarien wurde an alle 39 nationalen Universitäts-HNO-Kliniken und 20 akademischen Lehrkrankenhäuser mit HNO-Hauptabteilung versandt.

Ergebnisse

Die ausgefüllten Fragebögen von 31 Universitätskliniken (UK) und 10 akademische Lehrkrankenhäuser (ALK) gingen in die Auswertung ein. Es zeigten sich offensichtliche Diskrepanzen zwischen verfügbaren Ressourcen und tatsächlich verfügbaren digitalisierten Lehrinhalten. Weitere Kritikpunkte offenbarten sich in Bezug auf die Kommunikation mit der Medizinischen Fakultät, die digitale Infrastruktur und insbesondere in der oftmals mangelnden Kollaboration mit den zentralen Supportstrukturen, wie Medien‑, Didaktik- und Rechenzentren.

Schlussfolgerung

Es gibt durchaus positive Beispiele für eine gelungene Überführung der Präsenzlehre in das ausschließlich virtuelle Sommersemester 2020 innerhalb der Universitäts-HNO-Kliniken. Mehrheitlich aber überwiegen kritische Einschätzungen der Lehrbeauftragten bzw. Ärztlichen Direktoren gegenüber der aktuellen Lehrsituation. Eine zeitkritische strategische Weiterentwicklung ist dringend erforderlich.

Observation of a neutron spin resonance in the bilayered superconductor CsCa2Fe4As4F2

We report inelastic neutron scattering (INS) investigations on the bilayer Fe-based superconductor CsCa2Fe4As4F2above and below its superconducting transition temperatureTc≈ 28.9 K to investigate the presence of a neutron spin resonance. This compound crystallises in a body-centred tetragonal lattice containing asymmetric double layers of Fe2As2separated by insulating CaF2layers and is known to be highly anisotropic. Our INS study clearly reveals the presence of a neutron spin resonance that exhibits higher intensity at lower momentum transfer (Q) at 5 K compared to 54 K, at an energy of 15 meV. The energyERof the observed spin resonance is broadly consistent with the relationshipER= 4.9kBTc, but is slightly enhanced compared to the values observed in other Fe-based superconductors. We discuss the nature of the electron pairing symmetry by comparing the value ofERwith that deduced from the total superconducting gap value integrated over the Fermi surface.

Abstract A30: Combined IDO inhibitor and OX40L-armed-oncolytic-adenovirus therapy improves survival in murine glioblastoma

Glioblastoma diagnoses associate with upregulation of the immunosuppressive indoleamine-2,3-dioxygenase (IDO) enzyme, which correlates with poor prognoses. IDO inhibitors are immunometabolic adjuvants that can reverse protumor immunosuppression through increasing effector T-cell metabolism. To further stimulate antitumor T-cell activation, the OX40L-armed-oncolytic-adenovirus (Delta-24-RGDOX) can be used, which has shown to induce immune mechanisms that activate antitumor cytotoxic properties of T cells. Thus, we hypothesized that combining IDO inhibitors and Delta-24-RGDOX synergizes to produce a therapeutic effect in glioblastoma. In this study, we used a syngeneic glioblastoma orthotopic immunocompetent model to test the efficacy of combining Delta-24-RGDOX and an IDO inhibitor (1MT or indoximod). Delta-24-RGDOX treatment resulted in a significant survival benefit compared to the control groups (mean survival, 46.5 vs. 38.5 days, P=0.02). Interestingly, the combination of Delta-24-RGDOX and 1MT produced a higher percentage of long-term survivors compared to single therapy with Delta-24-RGDOX (50% vs. 20%, P=0.03). Moreover, when these long-term glioblastoma survivors were rechallenged with the same glioblastoma cells, we observed 100% survival, indicating the establishment of immune memory by the combination therapy. Furthermore, functional studies showed a significant increase in antitumor activity of splenocytes from glioblastoma-bearing combination-treated mice compared to Delta-24-RGDOX-treated mice (P=0.009). Additionally, immunophenotyping by flow cytometry revealed that glioblastoma-bearing combination-treated mice yielded the highest levels of PD-1/TIM-3/CD8+ T cells compared to all other treatment groups and decreased levels of immune-tolerant populations, including regulatory T cells and myeloid-derived suppressor cells, compared to Delta-24-RGDOX-only treated mice, and correlated with complete tumor elimination. Most importantly, these data support the use of immunometabolic adjuvants combined with virotherapy as a treatment for glioblastoma to improve its dismal outcomes.

Citation Format: Teresa T. Nguyen, Dong Ho Shin, Hong Jiang, Frederick Lang, Candelaria Gomez-Manzano, Juan Fueyo. Combined IDO inhibitor and OX40L-armed-oncolytic-adenovirus therapy improves survival in murine glioblastoma [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A30.

EXTH-38. ENGINEERED EXOSOMES FOR THERAPEUTIC GENE DELIVERY IN BRAIN TUMORS

The poor outcome of patients with glioblastoma (GBM) is at least partly due to the inability to deliver therapeutic agents to the tumor. We have shown that exosomes, naturally occurring nano-size extracellular vesicles, are capable of delivering antiglioma microRNAs (MiRs) to brain tumors (Lang, FM et al. Neuro Oncol, 2018;20(3):380–390). However, our studies suggested that there is significant opportunity to increase packaging efficiency and delivery specificity of exosomes. To this end, we engineered exosomes to express specific viral proteins (called eExos) in order to enhance packaging and delivery capabilities of antiglioma genes. These eExos are created by transfecting HEK 293 cells with plasmids containing viral proteins and a plasmid of the therapeutic gene. After 72 hrs, differential ultracentrifugation was used to isolate the exosomes. To test the efficacy of these novel eExos, we transfected them with a plasmid containing Cre recombinase (as the therapeutic gene), and treated U87 cells harboring a dsRed/eGFP Cre recombinase/LoxP site (U87dsR/GFP). In in vitro studies, treatment of U87dsR/GFP with a single dose of eExos resulted in 82% conversion rate of cells from red to green, compared to control exosomes (< 18% green cells). In in vivo studies, a single intratumoral injection of eExos into mice harboring 7-day old intracranial U87dsR/GFP gliomas, resulted in significant increases in green cells compared to control exosomes when tumors were harvested at day 10. Mechanistic studies employing florescent microscopy demonstrate that in contrast to natural exosomes, eExos deliver their cargo to the nucleus rather than to lysosomes, avoiding degradation of the delivered agent and facilitating expression of the plasmid. We conclude that eExos, engineered to contain specific viral proteins, are capable of packaging and delivering antiglioma genes more effectively than natural exosomes and may overcome the current inability to deliver biological therapeutic agents to brain tumors.

TMIC-37. INTERCELLULAR COMMUNICATION BETWEEN NORMAL AND TUMOR CELLS IN GLIOMA MICROENVIRONMENT

The interactions between tumors cells and their microenvironment are increasingly recognized as contributors to tumor growth and therapeutic resistance in glioblastoma (GBM). Mesenchymal Stem Cells (MSCs) have been implicated as components of the microenvironment of several cancers, but their contribution to GBM remains obscure. Recently we reported that GBMs contain cells resembling human mesenchymal stem cells, called Glioma-associated-MSCs (GA-hMSCs), based on our ability to isolate these cells from patient tumors (Figueroa, et al. Can Res 2017. 77, 5808–5819). In order to characterize the function of these cells in vivo, we used a PDGFRb promoter driven mouse model to track and modulate the behavior of endogenous MSCs (PDGFRb + cells). To generate tumors that mimic gliomas, we injected the RCAS-PDGF avian retrovirus into PDGFRb EGFP/nTVA mice. These mice express EGFP in PDGFRb expressing cells and RCAS receptor TVA under the control of the Nestin promoter and develop tumors. Immunostaining these tumors for GFP and CD31 determined that MSC like cells reside around blood vessels and are likely the major contributor of microvascular proliferation often seen in human gliomas. Additionally, we sought to see if there was communication between MSCs localized around blood vessels and the tumor. To this end, mice with Cre recombinase expression under the PDGFRb promoter were implanted with a GL-261 tumor harboring a dsRed/eGFP Cre recombinase/LoxP site. In these mice, tumor color change from red to green indicates transfer of Cre mRNA or protein from PDGFRb+ cells (MSCs) to tumor cells (GL-261dsRed/eGFP). We observed red to green transition in tumors, indicating that there is transfer of mRNA or protein, and further suggesting that there is direct communication between the tumor microenvironment and the tumor. Taken together, our findings emphasize the crucial role of MSCs in the tumor microenvironment.

EXTH-11. TREATMENT WITH DELTA-24-RGDOX OF SUBCUTANEOUS TUMORS RESULTS IN ABSCOPAL EFFECT ERADICATING INTRACRANIAL MELANOMAS

Immune checkpoint blockade has revolutionized cancer therapy; however the therapeutic benefit is limited to only a subset of patients with immunogenic (“hot”) tumors and is compromised by immune-related adverse events. We have reported the efficacy of oncolytic adenovirus Delta-24-RGDOX (DNX-2440) in syngeneic glioma mouse models. We hypothesized that localized treatment with the virus is effective against disseminated melanomas, including intracranial melanomas. We tested the hypothesis in the subcutaneous (s.c.)/s.c. and s.c./intracranial (i.c.) melanoma models derived from luciferase-expressing B16-Red-FLuc cells in C57BL/6 mice. First, through monitoring tumor growth with bioluminescence imaging, we found that, in both s.c./s.c. and s.c./i.c. models, three injections of Delta-24-RGDOX significantly inhibited the growth of both the virus-injected s.c. tumor and untreated distant s.c. or i.c. tumor, thereby prolonging survival. Next, through cell profiling with flow cytometry, we observed that the virus increased the presence of T cells and effector T cell frequency in the virus-injected tumor and mediated the same changes in T cells from peripheral blood, tumor-draining lymph nodes (TDLNs), spleens, and brain hemispheres with untreated tumor. Moreover, Delta-24-RGDOX decreased the frequency of exhausted T cells and regulatory T cells in the virus-injected and untreated i.c. tumors. Consequently, the virus promoted recruitment and/or in situ expansion of antigen-specific T cells in tumors expressing the target antigen. Therefore, we concluded that local intratumoral injection of Delta-24-RGDOX resulted in systemic immune activity against the disseminated tumors. Furthermore, we speculate that given the immunogenicity, cancer-selectivity and intratumoral administration of the virus, Delta-24-RGDOX is expected to have an improved safety profile when compared to immune checkpoint blockade treatment strategies. This is the first report demonstrating that local administration of oncolytic adenovirus results in eradication of intracranial tumors, suggesting Delta-24-RGDOX could be used to manage brain metastases of melanoma.

EXTH-62. STEM CELL DELIVERY OF ONCOLYTIC ADENOVIRUS DNX-2401 FOLLOWING SURGICAL RESECTION FOR THE TREATMENT OF GLIOBLASTOMA

BACKGROUND

The oncolytic virus DNX-2401 (Delta-24-RGD) is a novel treatment of GBM. While prior studies have examined intratumoral injection of DNX-2401 into recurrent GBM, the potential of delivering DNX-2401 into the surgical resection cavity using tumor-tropic human mesenchymal stem cells (MSCs) has not been evaluated. We hypothesize that exploiting a fibrin-based scaffold for transplanting MSCs loaded with DNX-2401 (MSCs-DNX-2401) into the resection cavity will improve viral delivery, decrease GBM recurrence, and extend overall survival.

METHODS

MSCs-DNX-2401 were seeded in a fibrin matrix or suspended in PBS and placed in the upper wells of transwell plates with U87 cells placed below. After one week, U87 cells were counted to compare rates of cellular killing and confirm release of DNX-2401 from fibrin-seeded MSCs. U87 cells were transduced with mCherry-Luciferase and implanted into the brains of athymic mice (N=16). After fluorescence-guided surgical resection of glioma xenografts, MSCs (control) or MSCs-DNX-2401 were delivered in the resection cavity using a fibrin scaffold. Serial bioluminescence imaging (BLI) was used to monitor tumor recurrence.

RESULTS

In transwell experiments, MSCs-DNX-2401 seeded in fibrin were as effective as MSCs-DNX-2401 without the scaffold, indicating that fibrin did not negatively impact cell viability or viral release. In in vivo studies mimicking residual tumor after surgical resection, treatment of the post-resection cavity with MSCs-DNX-2401 suspended in fibrin permitted retention of MSCs-DNX-2401 within the tumor bed. Kaplan-Meier survival analyses revealed statistically significant improved survival after treatment with MSC-DNX-2401 in fibrin compared to controls with 50% of animals demonstrating complete responses according to BLI (p < 0.05).

CONCLUSION

Delivering DNX-2401 into the post-resection surgical cavity using MSCs seeded in fibrin is capable of eradicating residual GBM and prolonging overall survival. These studies support the clinical translation of this approach in newly diagnosed patients undergoing surgical resection of GBM.

TMIC-60. COMPREHENSIVE SPATIAL CHARACTERIZATION OF IMMUNE CELLS IN THE CNS BRAIN TUMOR MICROENVIRONMENT

Previous immune profiling in brain tumors has mostly focused on the high-density tumor areas, and as such, little is known about the nature and types of immunological responses that occur across the tumor landscape, including at the tumor-central nervous system (CNS) interface. En bloc resections of glioblastomas (n=10) and CNS lung metastases (n=10) were oriented on slides as whole mount wedges spanning three anatomical areas including the invasive edge, tumor region, and necrotic core. Tumor segmentation was performed and regional differences were immunologically analyzed for 770 immune genes using the NanoString nCounter System with CIBERSORT analysis to delineate immune gene signatures. The analysis was validated using multiplex immunohistochemistry (IHC). The top upregulated immune genes in the GBM necrotic core were associated with macrophages, including the CD163 lineage marker, chemotactic factors (such as CCL18 and SAA1), and the phagocytosis stimulatory factors (such as IL-8 and MARCO). The necrotic core downregulates GBM antigens (such as IL13RA2 and MAGEB2), markers of dendritic cells (such as LILRA4), and immune stimulatory processes including MHC, IFN, IL-12, TNF, and ICOS expression. In direct contrast, the infiltrating edge of the GBM relative to the tumor is enriched with stimulators for NK cytotoxicity (i.e., CD244, the fractalkine receptor for immune cells), chemokines for thymocytes and dendritic cells, and immune stimulatory IL-12 receptors. Glioblastoma has rare focal isolated areas of CD3 T-cell reactivity within the tumor. Similar to GBM, the necrotic center of lung metastases is enriched in immune suppressive macrophages, as reflected by CD163 IHC staining and arginase expression; however, they are more frequently infiltrated with M1 macrophages. Yet the majority of lung cancers are more diffusely infiltrated with CD3 T cells, especially at the infiltrating edge. In general, we noted distinct inter- and intratumoral immune gene signatures, with macrophages dominating the brain tumors, especially the necrotic core.

EXTH-27. ACTIVATING THE IMMUNITY WITHIN THE TUMOR USING VIROIMMUNOTHERAPY: DELTA-24-RGD ONCOLYTIC ADENOVIRUS ARMED WITH THE IMMUNOPOSITIVE REGULATOR GITRL

Based on promising results of recent clinical trials using oncolytic viruses, virotherapy is evolving as an alternative to treat patients with malignant glioma. Our group developed the oncolytic adenovirus Delta-24-RGD (DNX-2401) that is being tested, alone or in combination with anti-PD1, in clinical trials for recurrent glioblastoma (NCT00805376; NCT01956734; NCT02798406). The results suggest that, besides the expected oncolytic effect, the injection of the pathogen initiated, in a subset of patients, an anti-tumoral immunity that led to 20% of long-term survivors (3.5–5 years). To further enhance this effect, we have armed Delta-24-RGD to express the co-stimulatory ligand GITRL, and generated Delta-24-GREAT. The intracranial injection of Delta-24-GREAT prolonged the survival of GL261 glioma-bearing immunocompetent mice when compared to Delta-24-RGD treatment (P=0.002, log-rank test). Delta-24-GREAT treatment resulted in enhanced frequency of tumor-infiltrating lymphocytes: T lymphocytes (CD45+/CD3+) and cytotoxic T lymphocytes (CD45+CD3+CD8+). Functional studies performed by culturing splenocytes from Delta-24-GREAT-treated mice with glioma cells and analyzing secretion of Th1 cytokines, such as IL2 and IFN-γ, showed that lymphocytes recognized not only viral antigens but also tumoral antigens, suggesting the triggering of anti-tumoral immunity. Of interest, Delta-24-GREAT treatment resulted in an antigen-restricted anti-tumor memory effect and in the generation of central immune memory. Thus, rechallenging the survivor mice from the first experiment with a second implantation of glioma cells did not lead to tumor growth, and we detected an increased frequency of central memory CD8+ T cells (CD45+CD62L+). However, survivor mice developed lethal tumors when implanted intracranially with B16/F10 melanoma cells, strongly indicating that the developed immune response was specific for GL261 glioma antigens. This is a novel approach using an oncolytic adenovirus expressing GITRL to target cancer and to stimulate the immunity within the tumor. Our data strongly indicate that this type of strategy may be further developed to treat patients with malignant glioblastoma.

Merlin modulates process outgrowth and synaptogenesis in the cerebellum

Neurofibromatosis type 2 (NF2) patients are prone to develop glial-derived tumors in the peripheral and central nervous system (CNS). The Nf2 gene product -Merlin is not only expressed in glia, but also in neurons of the CNS, where its function still remains elusive. Here, we show that cerebellar Purkinje cells (PCs) of isoform-specific Merlin-deficient mice were innervated by smaller vGluT2-positive clusters at presynaptic terminals than those of wild-type mice. This was paralleled by a reduction in frequency and amplitude of miniature excitatory postsynaptic currents (mEPSC). On the contrary, in conditional transgenic mice in which Merlin expression was specifically ablated in PCs (L7Cre;Nf2^fl/fl), we found enlarged vGluT2-positive clusters in their presynaptic buttons together with increased amplitudes of miniature postsynaptic currents. The presynaptic terminals of these PCs innervating neurons of the deep cerebellar nuclei were also enlarged. When exploring mice with Merlin-deficient granule cells (GCs) (Math1Cre;Nf2^fl/fl), we found cerebellar extracts to contain higher amounts of vGluT1 present in parallel fiber terminals. In parallel, mEPSC frequency was increased in Math1Cre;Nf2^fl/fl mice. On the contrary, VGluT2 clusters in cerebellar glomeruli composed of NF2-deficient presynaptic Mossy fiber terminals and NF2-deficient postsynaptic GC were reduced in size as shown for isoform-specific knockout mice. These changes in Math1Cre;Nf2^fl/fl-deficient mice were paralleled by an increased activation of Rac1-Cofilin signaling which is known to impact on cytoskeletal reorganization and synapse formation. Consistent with the observed synaptic alterations in these transgenic mice, we observed altered ultrasonic vocalization, which is known to rely on proper cerebellar function. No gross morphological changes or motor coordination deficits were observed in any of these transgenic mice. We therefore conclude that Merlin does not regulate overall cerebellar development, but impacts on pre- and post-synaptic terminal organization.

Weaning practices in phenylketonuria vary between health professionals in Europe

Background

In phenylketonuria (PKU), weaning is considered more challenging when compared to feeding healthy infants. The primary aim of weaning is to gradually replace natural protein from breast milk or standard infant formula with solids containing equivalent phenylalanine (Phe). In addition, a Phe-free second stage L-amino acid supplement is usually recommended from around 6 months to replace Phe-free infant formula. Our aim was to assess different weaning approaches used by health professionals across Europe.

Methods

A cross sectional questionnaire (survey monkey®) composed of 31 multiple and single choice questions was sent to European colleagues caring for inherited metabolic disorders (IMD). Centres were grouped into geographical regions for analysis.

Results

Weaning started at 17–26 weeks in 85% (n = 81/95) of centres, >26 weeks in 12% (n = 11/95) and < 17 weeks in 3% (n = 3/95). Infant's showing an interest in solid foods, and their age, were important determinant factors influencing weaning commencement. 51% (n = 48/95) of centres introduced Phe containing foods at 17–26 weeks and 48% (n = 46/95) at >26 weeks. First solids were mainly low Phe vegetables (59%, n = 56/95) and fruit (34%, n = 32/95).

A Phe exchange system to allocate dietary Phe was used by 52% (n = 49/95) of centres predominantly from Northern and Southern Europe and 48% (n = 46/95) calculated most Phe containing food sources (all centres in Eastern Europe and the majority from Germany and Austria). Some centres used a combination of both methods.

A second stage Phe-free L-amino acid supplement containing a higher protein equivalent was introduced by 41% (n = 39/95) of centres at infant age 26–36 weeks (mainly from Germany, Austria, Northern and Eastern Europe) and 37% (n = 35/95) at infant age > 1y mainly from Southern Europe. 53% (n = 50/95) of centres recommended a second stage Phe-free L-amino acid supplement in a spoonable or semi-solid form.

Conclusions

Weaning strategies vary throughout European PKU centres. There is evidence to suggest that different infant weaning strategies may influence longer term adherence to the PKU diet or acceptance of Phe-free L-amino acid supplements; rendering prospective long-term studies important. It is essential to identify an effective weaning strategy that reduces caregiver burden but is associated with acceptable dietary adherence and optimal infant feeding development.