EPI-X4, a CXCR4 antagonist inhibits tumor growth in pancreatic cancer and lymphoma models

Endogenous peptide inhibitor for CXCR4 (EPI-X4) is a CXCR4 antagonist with potential for cancer therapy. It is a processed fragment of serum albumin from the hemofiltrate of dialysis patients. This study reports the efficacy of fifteen EPI-X4 derivatives in pancreatic cancer and lymphoma models. In vitro, the peptides were investigated for antiproliferation (cytotoxicity) by MTT assay. The mRNA expression for CXCR4 and CXCL12 was determined by RT-PCR, chip array and RNA sequencing. Chip array analysis yielded 634 genes associated with CXCR4/CXCL12 signaling. About 21% of these genes correlated with metastasis in the context of cell motility, proliferation, and survival. Expression levels of these genes were altered in pancreatic cancer (36%), lymphoma models (53%) and in patients' data (58%). EPI-X4 derivatives failed to inhibit cell proliferation due to low expression of CXCR4 in vitro, but inhibited tumor growth in the bioassays with significant efficacy. In the pancreatic cancer model, EPI-X4a, f and k inhibited mean tumor growth by > 50% and even caused complete remissions. In the lymphoma model, EPI-X4b, n and p inhibited mean tumor growth by > 70% and caused stable disease. Given the non-toxic and non-immunogenic properties of EPI-X4, these findings underscore its status as a promising therapy of pancreatic cancer and lymphoma and warrant further studies. SIMPLE SUMMARY: This study examined the value of chemokine receptor CXCR4 as an antineoplastic target for the endogenous peptide inhibitor of CXCR4 (EPI-X4), a 12-meric peptide derived from serum albumin. EPI-X4 inhibits CXCR4 interaction with its natural ligand, CXCL12 (SDF1). Therefore, malignancies (including pancreatic cancer and lymphoma) that depend on the CXCR4/CXCL12 pathway for progression can be targeted with EPI-X4. Of 634 genes that were linked to the CXCR4/CXCL12 pathway, 21% were associated with metastasis. In cultured human Suit2-007 pancreatic cancer cells, CXCR4 showed low to undetectable expression, which was why EPI-X4 did not inhibit pancreatic cancer cell proliferation. These findings were different in vivo, where CXCR4 was highly expressed and EPI-X4 inhibited tumor growth in rodents harboring pancreatic cancer or lymphoma. In the pancreatic cancer model, EPI-X4 derivatives a, f and k caused complete remissions, while in lymphomas EPI-X4 derivatives b, n and p caused stable disease.

Integration of ζ-deficient CARs into the CD3-zeta gene conveys potent cytotoxicity in T and NK cells

Chimeric antigen receptor (CAR)-redirected immune cells hold significant therapeutic potential for oncology, autoimmune diseases, transplant medicine, and infections. All approved CAR-T therapies rely on personalized manufacturing using undirected viral gene transfer, which results in non-physiological regulation of CAR-signaling and limits their accessibility due to logistical challenges, high costs and biosafety requirements. Random gene transfer modalities pose a risk of malignant transformation by insertional mutagenesis. Here, we propose a novel approach utilizing CRISPR-Cas gene editing to redirect T-cells and natural killer (NK) cells with CARs. By transferring shorter, truncated CAR-transgenes lacking a main activation domain into the human CD3ζ (CD247) gene, functional CAR fusion-genes are generated that exploit the endogenous CD3ζ gene as the CAR's activation domain. Repurposing this T/NK-cell lineage gene facilitated physiological regulation of CAR-expression and redirection of various immune cell types, including conventional T-cells, TCRγ/δ T-cells, regulatory T-cells, and NK-cells. In T-cells, CD3ζ in-frame fusion eliminated TCR surface expression, reducing the risk of graft-versus-host disease in allogeneic off-the-shelf settings. CD3ζ-CD19-CAR-T-cells exhibited comparable leukemia control to T cell receptor alpha constant (TRAC)-replaced and lentivirus-transduced CAR-T-cells in vivo. Tuning of CD3ζ-CAR-expression levels significantly improved the in vivo efficacy. Notably, CD3ζ gene editing enabled redirection of NK-cells without impairing their canonical functions. Thus, CD3ζ gene editing is a promising platform for the development of allogeneic off-the-shelf cell therapies using redirected killer lymphocytes.

Establishing an MSU service in a medium-sized German urban area-clinical and economic considerations

Background and purpose

Mobile stroke units (MSU) have been demonstrated to improve prehospital stroke care in metropolitan and rural regions. Due to geographical, social and structural idiosyncrasies of the German city of Mannheim, concepts of established MSU services are not directly applicable to the Mannheim initiative. The aim of the present analysis was to identify major determinants that need to be considered when initially setting up a local MSU service.

Methods

Local stroke statistics from 2015 to 2021 were analyzed and circadian distribution of strokes and local incidence rates were calculated. MSU patient numbers and total program costs were estimated for varying operating modes, daytime coverage models, staffing configurations which included several resource sharing models with the hospital. Additional case-number simulations for expanded catchment areas were performed.

Results

Median time of symptom onset of ischemic stroke patients was 1:00 p.m. 54.3% of all stroke patients were admitted during a 10-h time window on weekdays. Assuming that MSU is able to reach 53% of stroke patients, the average expected number of ischemic stroke patients admitted to MSU would be 0.64 in a 10-h shift each day, which could potentially be increased by expanding the MSU catchment area. Total estimated MSU costs amounted to € 815,087 per annum. Teleneurological assessment reduced overall costs by 11.7%.

Conclusion

This analysis provides a framework of determinants and considerations to be addressed during the design process of a novel MSU program in order to balance stroke care improvements with the sustainable use of scarce resources.

Establishment and Thorough Characterization of Xenograft (PDX) Models Derived from Patients with Pancreatic Cancer for Molecular Analyses and Chemosensitivity Testing

Patient-derived xenograft (PDX) tumor models are essential for identifying new biomarkers, signaling pathways and novel targets, to better define key factors of therapy response and resistance mechanisms. Therefore, this study aimed at establishing pancreas carcinoma (PC) PDX models with thorough molecular characterization, and the identification of signatures defining responsiveness toward drug treatment. In total, 45 PC-PDXs were generated from 120 patient tumor specimens and the identity of PDX and corresponding patient tumors was validated. The majority of engrafted PDX models represent ductal adenocarcinomas (PDAC). The PDX growth characteristics were assessed, with great variations in doubling times (4 to 32 days). The mutational analyses revealed an individual mutational profile of the PDXs, predominantly showing alterations in the genes encoding KRAS, TP53, FAT1, KMT2D, MUC4, RNF213, ATR, MUC16, GNAS, RANBP2 and CDKN2A. Sensitivity of PDX toward standard of care (SoC) drugs gemcitabine, 5-fluorouracil, oxaliplatin and abraxane, and combinations thereof, revealed PDX models with sensitivity and resistance toward these treatments. We performed correlation analyses of drug sensitivity of these PDX models and their molecular profile to identify signatures for response and resistance. This study strongly supports the importance and value of PDX models for improvement in therapies of PC.

Integration of ζ-deficient CARs into the CD3-zeta gene conveys potent cytotoxicity in T and NK cells

Chimeric antigen receptor (CAR)-reprogrammed immune cells hold significant therapeutic potential for oncology, autoimmune diseases, transplant medicine, and infections. All approved CAR-T therapies rely on personalized manufacturing using undirected viral gene transfer, which results in non-physiological regulation of CAR-signaling and limits their accessibility due to logistical challenges, high costs and biosafety requirements. Here, we propose a novel approach utilizing CRISPR-Cas gene editing to redirect T cells and natural killer (NK) cells with CARs. By transferring shorter, truncated CAR-transgenes lacking a main activation domain into the human CD3 ζ (CD247) gene, functional CAR fusion-genes are generated that exploit the endogenous CD3 ζ gene as the CAR's activation domain. Repurposing this T/NK-cell lineage gene facilitated physiological regulation of CAR-expression and reprogramming of various immune cell types, including conventional T cells, TCRγ/δ T cells, regulatory T cells, and NK cells. In T cells, CD3 ζ in-frame fusion eliminated TCR surface expression, reducing the risk of graft-versus-host disease in allogeneic off-the-shelf settings. CD3 ζ-CD19-CAR-T cells exhibited comparable leukemia control to T cell receptor alpha constant ( TRAC )-replaced and lentivirus-transduced CAR-T cells in vivo . Tuning of CD3 ζ-CAR-expression levels significantly improved the in vivo efficacy. Compared to TRAC -edited CAR-T cells, integration of a Her2-CAR into CD3 ζ conveyed similar in vitro tumor lysis but reduced susceptibility to activation-induced cell death and differentiation, presumably due to lower CAR-expression levels. Notably, CD3 ζ gene editing enabled reprogramming of NK cells without impairing their canonical functions. Thus, CD3 ζ gene editing is a promising platform for the development of allogeneic off-the-shelf cell therapies using redirected killer lymphocytes.

Key points

Integration of ζ-deficient CARs into CD3 ζ gene allows generation of functional TCR-ablated CAR-T cells for allogeneic off-the-shelf use CD3 ζ-editing platform allows CAR reprogramming of NK cells without affecting their canonical functions.

[Acceptance of psychosocial bridging measures in dementia : Treatment observation during the COVID-19 pandemic]

BACKGROUND

In the event of a COVID-19-related absence from an outpatient treatment program, patients suffering from dementia and their caregivers were offered support from a distance. The aim was to examine the extent of the participants' burden as well as how the offer was accepted and evaluated.

MATERIAL AND METHODS

All participants (n = 63) were offered supportive telephone contact over a period of 8 weeks at varying frequencies (weekly, fortnightly). In addition patients received cognitive and physical tasks by mail every 2 weeks. In order to examine the acceptance of the support, data collected from clinical routine were included in a treatment observation. Additionally, all participants were asked to evaluate the support retrospectively.

RESULTS

Out of 63 contacted participants, 45 were included in the treatment observation. The telephone support was very well accepted and a tendency towards higher agreement could be ascertained by caregivers. The experience of burden remained stable at a moderate level for all participants; however, caregivers were significantly more burdened.

CONCLUSION

The present treatment observation shows the acceptance of a location-independent psychosocial treatment program for dementia for future pandemics or treatment failure as well as for the routine care, e.g. for patients with restricted mobility or those living in rural areas without direct hospital connection. In particular, our data strengthen the importance of programs for caregivers in order to alleviate their burden.

Decreased eukaryotic initiation factors expression upon temozolomide treatment-potential novel implications for eIFs in glioma therapy

PURPOSE

Since glioma therapy is currently still limited until today, new treatment options for this heterogeneous group of tumours are of great interest. Eukaryotic initiation factors (eIFs) are altered in various cancer entities, including gliomas. The purpose of our study was to evaluate the potential of eIFs as novel targets in glioma treatment.

METHODS

We evaluated eIF protein expression and regulation in 22 glioblastoma patient-derived xenografts (GBM PDX) after treatment with established cytostatics and with regards to mutation profile analyses of GBM PDX.

RESULTS

We observed decreased expression of several eIFs upon temozolomide (TMZ) treatment independent from the phosphatidylinositol 3-kinase (PI3K)/ AKT/ mammalian target of the rapamycin (mTOR) signalling pathway. These effects of TMZ treatment were not present in TMZ-resistant PDX. Combination therapy of regorafenib and TMZ re- established the eIF/AKT/mTOR axis.

CONCLUSION

Our study provides novel insights into chemotherapeutic effects on eIF regulation in gliomas and suggests that eIFs are interesting candidates for future research to improve glioma therapy.

A combined computational and functional approach identifies IGF2BP2 as a driver of chemoresistance in a wide array of pre-clinical models of colorectal cancer

AIM

Chemoresistance is a major cause of treatment failure in colorectal cancer (CRC) therapy. In this study, the impact of the IGF2BP family of RNA-binding proteins on CRC chemoresistance was investigated using in silico, in vitro, and in vivo approaches.

METHODS

Gene expression data from a well-characterized cohort and publicly available cross-linking immunoprecipitation sequencing (CLIP-Seq) data were collected. Resistance to chemotherapeutics was assessed in patient-derived xenografts (PDXs) and patient-derived organoids (PDOs). Functional studies were performed in 2D and 3D cell culture models, including proliferation, spheroid growth, and mitochondrial respiration analyses.

RESULTS

We identified IGF2BP2 as the most abundant IGF2BP in primary and metastastatic CRC, correlating with tumor stage in patient samples and tumor growth in PDXs. IGF2BP2 expression in primary tumor tissue was significantly associated with resistance to selumetinib, gefitinib, and regorafenib in PDOs and to 5-fluorouracil and oxaliplatin in PDX in vivo. IGF2BP2 knockout (KO) HCT116 cells were more susceptible to regorafenib in 2D and to oxaliplatin, selumitinib, and nintedanib in 3D cell culture. Further, a bioinformatic analysis using CLIP data suggested stabilization of target transcripts in primary and metastatic tumors. Measurement of oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) revealed a decreased basal OCR and an increase in glycolytic ATP production rate in IGF2BP2 KO. In addition, real-time reverse transcriptase polymerase chain reaction (qPCR) analysis confirmed decreased expression of genes of the respiratory chain complex I, complex IV, and the outer mitochondrial membrane in IGF2BP2 KO cells.

CONCLUSIONS

IGF2BP2 correlates with CRC tumor growth in vivo and promotes chemoresistance by altering mitochondrial respiratory chain metabolism. As a druggable target, IGF2BP2 could be used in future CRC therapy to overcome CRC chemoresistance.

Abstract 5204: Preclinical models for translational immuno-oncology research: Rare patient-derived xenografts on humanized mice

Background

The preclinical evaluation of novel immune checkpoint modulators is dependent on models with functional human immune cells. In previous experiments, we have demonstrated, that we can use either peripheral blood mononuclear cells (PBMC), subset of immune cells like NK cells or hematopoietic stem cells (HSC) to establish a humanized immune system on highly immunodeficient 1st and 2nd generation NOG mice with functional T-, B-, and NK cells, as well as monocytes and dendritic cells. Furthermore, we determined PD-L1 expression as a predictive marker and target for immunotherapy on different patient-derived xenografts (PDX). By co-transplantation of rare PDX, like leukemia or Nuclear-protein-in-testis (NUT) carcinoma, we successfully generated a fully human tumor-immune-cell model in mice. Finally, we evaluated the functionality of the model by the treatment with checkpoint inhibitors like Ipilimumab (Ipi), Nivolumab (Nivo) or Pembrolizumab (Pembro). In parallel, we investigated the functionality of the human immune cells and evaluated concepts for combination therapies i.e. with chemotherapy or radiation.

Methods

HSC-humanized mice were generated by i.v. HSC transplantation and engraftment of immune cells was monitored by FACS analysis. For PBMC-humanized mice, immune cells were implanted i.v.. PDX models from different entities (leukemia or NUT carcinoma) were transplanted on HSC-humanized (HIS) mice and treated with Ipi, Nivo and Pembro alone or in combination with radiation. Blood and tumor samples were analysed by FACS for immune cell infiltration and activation.

Results

The transplanted HSC showed engraftment in mice with proliferation and differentiation. 14 weeks after HSC inoculation up to 20% of the human immune cells in the blood were T-cells, characterized by a high PD-1 expression. We have transplanted PDX from different tumor entities on HSC-humanized mice. Most of the investigated PDX (>70%) successfully engrafted on humanized mice and showed no significant difference in tumor growth compared to growth on non-humanized mice. However, for some PDX we observed a delayed tumor growth or a complete rejection. Engraftment delay seems to correlate with the PD-L1 expression of PDX (the higher PD-L1, then the higher growth delay). Furthermore, our results demonstrate the functionality of the engrafted human immune cells against some PDX. Treatment with Ipi, Nivo or Pembro led to a minor tumor growth delay. Response to checkpoint inhibitors showed a correlation to innate immune response and PD-L1 expression of PDX and could further be increased by combination with radiotherapy.

Conclusions

Our humanized immune-PDX models enable appropriate preclinical translational research on tumor immune biology and the evaluation of new therapies and combinations, as well as the identification and validation of biomarkers for immune therapy, especially in rare PDX models.

Citation Format: Maria Stecklum, Annika Wulf-Goldenberg, Bernadette Brzezicha, Wolfgang Walther, Jens Hoffmann. Preclinical models for translational immuno-oncology research: Rare patient-derived xenografts on humanized mice. [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 5204.

Abstract 4674: Patient-derived xenograft (PDX) and corresponding cell line models from glioblastoma for drug development, immuno-oncology and translational research

Background: Glioblastoma (GBM) is the most common malignant brain tumor in adults, with about 90% of tumors developing de novo. Their heterogeneity, aggressiveness and infiltrative growth limit success of current standard of care (SoC) therapy and efficacy of new therapeutic approaches. For drug development a large panel of patient-derived tumor cell models is needed to generate most comparable in vitro and in vivo platform reflecting the complex biology of glioblastoma. Glioblastoma cell lines from patient-derived xenografts (PDX) preserve many patient specific characteristics and to perform the essential steps of pre-clinical drug development from in vitro screening to orthotopic in vivo approaches under conditions, which closely resemble the clinical situation. Further, GBM PDX models are useful for immune oncology research.

Methods: A panel of 26 glioblastoma PDX models was established on immunodeficient mice (15 out of these established orthotopically). All models were characterized for drug sensitivity and molecular profile using panel and transcriptome sequencing. From these, three corresponding tumor cell lines were successfully established and characterized. Quality and identity of the models was performed by FACS and PCR analysis. Expression profile, drug sensitivity and growth behavior was determined and compared in vitro and after re-transplantation in vivo with the original PDX glioma model. In addition, we employed GBM PDX models for checkpoint-inhibitor sensitivity in humanized mouse settings.

Results: Drug testing was performed in s.c. and orthotopic models revealed, that best treatment responses in s.c. models (tumor growth inhibition > 50%) were observed for SoC temozolomide (TMZ), irinotecan and bevacizumab. Molecular characterization identified all our models as IDH-wt (R132) with frequent mutations in PARP1, EGFR, TP53, FAT1, and within the PI3K/AKT/mTOR pathway. Their expression profiles resemble proposed mesenchymal, proneural and classical GBM molecular subtypes. Further, treatment of GBM PDX with ipilimumab, nivolumab or pembrozolumab generated minor growth delay.

Conclusions: In drug sensitivity screening, irinotecan or bevacizumab were identified as alternative treatment options in TMZ resistant GBM PDX models. Our data demonstrate, that the established platform of s.c. and orthotopic GBM PDX is valuable for drug development and can well be complemented by a PDX-derived cell lines for in vitro screens. Furthermore, these models can be used for the evaluation of new immune-oncology therapies.

Citation Format: Joshua Alcaniz, Lars Winkler, Maria Stecklum, Hagen Wieland, Antje Siegert, Michael Becker, Bernadette Brzezicha, Wolfgang Walther, Jens Hoffmann. Patient-derived xenograft (PDX) and corresponding cell line models from glioblastoma for drug development, immuno-oncology and translational research. [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 4674.

Abstract 44: An in vivo platform of pre-characterized renal cell carcinoma (RCC) patient-derived xenograft models allows the preclinical evaluation of patient-tailored intervention strategies

Renal cell carcinoma (RCC), is the most common kidney cancer of adults, originating in the lining of the proximal convoluted tubule. Prognosis is poor in patients with advanced or metastasized RCC. Drug resistance towards Standard of Care (SoC, incl. everolimus, sorafenib, or sunitinib) drugs develops frequently within months. Therefore, development of novel options to target acquired TKI resistance mechanisms in advanced and metastatic RCC is still an urgent medical need. Preclinical models with high translational relevance can promote the implementation of novel personalized therapies. To evaluate novel targeted therapies and their combinations in preclinical settings, patient-derived xenograft (PDX) models represent valuable tools. Responsible local ethics committees approved usage of patient tissue and all animal procedures. In this study, RCC tissue from 167 patients was collected and xenotransplanted in mice. Partially, a multi-region approach, xenografting tissue from different regions of one tumor, was used. PDX models were characterized by immunohistochemistry (Ki-67, CD31, Pax2 and Pax8 antibodies), gene expression, copy number variations and mutational analyses. To evaluate in vivo drug response of RCC PDX models, mice transplanted with PDX tumors were treated with bevacizumab (i.p.), with everolimus, sorafenib, or sunitinib (p.o.). Adopted clinical response criteria for solid tumors (RECIST) were applied to classify the anti-tumor activity of the tested compounds in RCC PDX models. Next generation sequencing (NGS, panel) and transcriptome data were used to compare primary tumors and metastases. A comprehensive panel of subcutaneous RCC PDX models with well-conserved molecular and pathological features over multiple passages was established. The overall take for the RCC PDX in this study was 21%. Tumor growth characteristics were heterogeneous throughout the different models but were stable during in vivo passaging. Drug screening towards four SoC drugs, targeting the VEGF and PI3K/mTOR pathway, revealed individual and heterogeneous response profiles in the PDX, resembling the clinical situation. Intra-tumor heterogeneity can be assessed via PDX models from multi-tumor regions from one patient in our platform. Development of corresponding in vitro cell culture models from the PDX enables advanced high throughput drug screening in a personalized context. Analyzing novel targeted molecules is possible due to the pre-established molecular characterization of the PDX at the genomic and expression level. In conclusion, we established a new and molecularly characterized panel of RCC PDX models with high relevance for translational preclinical research.

Citation Format: Dennis Kobelt, Dennis Gürgen, Michael Becker, Mathias Dahlmann, Susanne Flechsig, Elke Schaeffeler, Florian A. Büttner, Christian Schmees, Regina Bohnert, Jens Bedke, Matthias Schwab, Johann J. Wendler, Martin Schostak, Burkhard Jandrig, Wolfgang Walther, Jens Hoffmann. An in vivo platform of pre-characterized renal cell carcinoma (RCC) patient-derived xenograft models allows the preclinical evaluation of patient-tailored intervention strategies [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 44.

Clinically relevant glioblastoma patient-derived xenograft models to guide drug development and identify molecular signatures

Glioblastoma (GBM) heterogeneity, aggressiveness and infiltrative growth drastically limit success of current standard of care drugs and efficacy of various new therapeutic approaches. There is a need for new therapies and models reflecting the complex biology of these tumors to analyze the molecular mechanisms of tumor formation and resistance, as well as to identify new therapeutic targets. We established and screened a panel of 26 patient-derived subcutaneous (s.c.) xenograft (PDX) GBM models on immunodeficient mice, of which 15 were also established as orthotopic models. Sensitivity toward a drug panel, selected for their different modes of action, was determined. Best treatment responses were observed for standard of care temozolomide, irinotecan and bevacizumab. Matching orthotopic models frequently show reduced sensitivity, as the blood-brain barrier limits crossing of the drugs to the GBM. Molecular characterization of 23 PDX identified all of them as IDH-wt (R132) with frequent mutations in EGFR, TP53, FAT1, and within the PI3K/Akt/mTOR pathway. Their expression profiles resemble proposed molecular GBM subtypes mesenchymal, proneural and classical, with pronounced clustering for gene sets related to angiogenesis and MAPK signaling. Subsequent gene set enrichment analysis identified hallmark gene sets of hypoxia and mTORC1 signaling as enriched in temozolomide resistant PDX. In models sensitive for mTOR inhibitor everolimus, hypoxia-related gene sets reactive oxygen species pathway and angiogenesis were enriched. Our results highlight how our platform of s.c. GBM PDX can reflect the complex, heterogeneous biology of GBM. Combined with transcriptome analyses, it is a valuable tool in identification of molecular signatures correlating with monitored responses. Available matching orthotopic PDX models can be used to assess the impact of the tumor microenvironment and blood-brain barrier on efficacy. Our GBM PDX panel therefore represents a valuable platform for screening regarding molecular markers and pharmacologically active drugs, as well as optimizing delivery of active drugs to the tumor.

Factors associated with the closure of German obstetric units and its effects on accessibility

Background

An increase in regionalization of obstetric services is being observed worldwide. This study investigated factors associated with the closure of obstetric units in hospitals in Germany and aimed to examine the effect of obstetric unit closure on accessibility of obstetric care.

Methods

Secondary data of all German hospital sites with an obstetrics department were analyzed for 2014 and 2019. Multivariate logistic regression was performed to identify factors associated with obstetrics department closure. Subsequently, the driving times to a hospital site with an obstetrics department were mapped, and different scenarios resulting from further regionalization were modelled.

Results

Of 747 hospital sites with an obstetrics department in 2014, 85 obstetrics departments closed down by 2019. Only the annual number of live births was observed to be a factor significantly associated with the closure of obstetrics departments (odds ratio: 0·995; confidence interval: 0.993-0.997). Areas in which driving times to the next hospital site with an obstetrics department exceeded the 30 and 40 min threshold increased from 2014 to 2019. Scenarios in which only hospital sites with a pediatrics department or hospital sites with an annual birth volume of ≥ 600 were considered resulted in large areas in which the driving times would exceed the 30 and 40 min threshold.

Conclusions

The annual number of live births is a factor significantly associated with the closure of obstetrics departments. Despite the closure, good accessibility is maintained for most areas in Germany. Although further regionalization may ensure high-quality care and efficiency, it will have an impact on accessibility.

Key messages

• Despite the closure of many obstetric departments, regional accessibility to obstetric care remains good for most areas in Germany.

• Further regionalization may ensure high-quality care and efficiency but will have an impact on accessibility.

A German study on the impact of stress on interparental relationship strain after preterm birth

Background

Relationship satisfaction is an important predictor of well-being. Few studies address the effects of stress on interparental relationships of parents with preterm infants. However, the experience of a preterm birth represents an extreme, stressful event and therefore may place a strain on a relationship. Our aim is to examine the impact of postnatal stress on maternal and paternal perceptions of relationship strain.

Methods

As part of the Neo-CamCare project, a retrospective cross-sectional study was conducted targeting parents with infants with a birth weight below 1,500 g. Linear regression was used to analyse the influence of stress on relationship strain.

Results

437 mothers and 301 fathers participated. Data indicate that interparental relationship strain experienced by fathers (M = 2.61, SD = 1.46) is lower than strain experienced by mothers (M = 3.43, SD = 1.7). The stress level due to the infant's behaviour and appearance is lower in fathers (M = 2.53, SD = 0.95) than in mothers (M = 2.98, SD = 1.05). Stress due to parental role change is higher in mothers (M = 3.37, p = 1.04) than in fathers (M = 2.49, SD = 0.99). Regression analyses show that stress due to behaviour and appearance, as well as parental role change, can be associated with relationship strain in mothers. For fathers, only stress experienced due to the behaviour and appearance can be associated with relationship strain, whereas parental role change is not significant.

Conclusions

Our data illustrate that relationship strain can result from stress in mothers and fathers, indicating the need for stress prevention measures for both. Only mothers show relationship strain due to stress in their parental role. Although it is unclear what mechanisms underlie these findings, we assume that the maternal role is still primarily associated with child care. One way to relieve maternal stress could be to increase psychological support and the promotion paternal involvement in the postnatal period.

Key messages

Human, mouse scRNA-seq and flow cytometry data in ischemic heart failure models predict immune cell activation signatures with altered endothelial cell cross talk

 

Chronic ischemic Heart Failure (HF) with reduced ejection fraction is marked by adverse remodelling and sustained inflammation. The effects of monocytes and T cells in early state immune responses after myocardial infarction are known, to date their role in progression and maintenance of chronic HF remains elusive.

Single cell RNA sequencing of peripheral immune cells from healthy and HF donors revealed a significant increase of the antigen presentation (i.e. HLA-DRB5) and co-stimulatory molecules (i.e. ICAM-1) on monocytes, while the elevation of the T effector memory population in HF patients shows enhanced T cell activation. Subsequent flow cytometry validation in 55 healthy and 110 HF patients confirmed that HF derived monocytes have elevated levels of HLA-DRB5 predicts increased ICAM-1 and TREM-1 (p<0.0001 for both), indicating enhanced T cell activation capacity. In addition, the activated fraction of both CD4+ and CD8+ T cells, including central memory, effector memory and TEMRA cells, is significantly enriched in the HF patients (p<0.0001 for both) with reduction of the naïve T cells. T cell receptor (TCR) sequencing of age matched healthy and HF donors showed an increase in the relative TCR clonality in HF patients, indicating an expansion of the circulating T cells.

ScRNA-seq murine myocardial infarction (MI) time course data (day (d) 0/1/3/7/14/28/48 post-MI), found a progressive increase in Th17 cells and activated CD8+ T cells in the cardiac tissue at d48 (2.8x-, and 2.7x-fold, respectively) relative to d0. The T cell imbalance was marked by loss of immunosuppressive markers such as Lef1 (p=2e-30) in T cell clusters primarily populated by d48 relative to d0.

Mechanistically the downstream effects of the immune cell activation were analysed in the serum of HF patients, where increased levels of sICAM-1, IL-6 and TNFRI levels (1.75x-, 5.30x-, 2.63x-fold, respectively) could be detected. Furthermore, treatment of endothelial cells with the conditioning media from HF-immune cells induced capability to adhere with monocytes in a co-culture system but also decreased the checkpoint inhibitor molecule PD-L1, a known blocker of autoreactive T cells.

These data link HF with enhanced monocyte and T cell activation as well as T cell clonal expansion, along with increased T cell numbers in mouse hearts post-MI. These data suggest HF is may drive impaired resolution of inflammation in cardiac tissue and facilitate adverse remodelling and cardiac damage. Further studies will assess the specific role of chronic monocyte and T cell activation in the progression of heart failure.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): DFG -Deutsche ForschungsgemeinschaftDZHK -Deutsches Zentrum für Herzkreislauferkrankungen

A Molecularly Characterized Preclinical Platform of Subcutaneous Renal Cell Carcinoma (RCC) Patient-Derived Xenograft Models to Evaluate Novel Treatment Strategies

Renal cell carcinoma (RCC) is a kidney cancer with an onset mainly during the sixth or seventh decade of the patient’s life. Patients with advanced, metastasized RCC have a poor prognosis. The majority of patients develop treatment resistance towards Standard of Care (SoC) drugs within months. Tyrosine kinase inhibitors (TKIs) are the backbone of first-line therapy and have been partnered with an immune checkpoint inhibitor (ICI) recently. Despite the most recent progress, the development of novel therapies targeting acquired TKI resistance mechanisms in advanced and metastatic RCC remains a high medical need. Preclinical models with high translational relevance can significantly support the development of novel personalized therapies. It has been demonstrated that patient-derived xenograft (PDX) models represent an essential tool for the preclinical evaluation of novel targeted therapies and their combinations. In the present project, we established and molecularly characterized a comprehensive panel of subcutaneous RCC PDX models with well-conserved molecular and pathological features over multiple passages. Drug screening towards four SoC drugs targeting the vascular endothelial growth factor (VEGF) and PI3K/mTOR pathway revealed individual and heterogeneous response profiles in those models, very similar to observations in patients. As unique features, our cohort includes PDX models from metastatic disease and multi-tumor regions from one patient, allowing extended studies on intra-tumor heterogeneity (ITH). The PDX models are further used as basis for developing corresponding in vitro cell culture models enabling advanced high-throughput drug screening in a personalized context. PDX models were subjected to next-generation sequencing (NGS). Characterization of cancer-relevant features including driver mutations or cellular processes was performed using mutational and gene expression data in order to identify potential biomarker or treatment targets in RCC. In summary, we report a newly established and molecularly characterized panel of RCC PDX models with high relevance for translational preclinical research.

Abstract 3095: Breaking the crosstalk of the cellular tumorigenic network in NSCLC by a highly effective drug combination

Background: Non-small cell lung cancer (NSCLC) is commonly diagnosed at advanced stages with limited treatment options particularly in tumors without targetable driver mutations.

Methods: Considering previously published criteria for selecting drug combinations for overcoming drug resistances1, we have established a low dose combination therapy with cabozantinib, afatinib, etoricoxib and plerixafor. Utilizing NSCLC patient-derived xenograft (PDX) models we aimed to use this drug regimen to disrupt paracrine substitutional signaling within the tumorigenic network in order to circumvent pre-existing and adaptive drug resistances. In contrast to daily dosing for respective monotherapies the low dose treatment was paused every five days for two days.

Result: All PDX tumors treated, including highly therapy-resistant adeno- and squamous cell carcinomas without identifiable driver mutations, were completely suppressed by this drug regimen leading to an Objective Response Rate of 81% and a Clinical Benefit Rate of 100%. After treatment discontinuation growth suppression remained until the end of the follow-up period with only slight increase in tumor growth. The application and the safety profile of this low dose therapy regimen was well manageable and without pronounced side effects in this pre-clinical setting.

Discussion: For the first time we show that simultaneous inhibition of pathways forming the cellular tumorigenic network in NSCLC tumors is highly effective and overcomes drug resistances for monotherapies. All of the drugs used in this combination regimen are approved for different indications and therefore readily available. Conclusion: Our results emphatically encourage a setup for a clinical study in advanced stage NSCLC patients without targetable driver mutations combining the drugs cabozantinib, afatinib, plerixafor and etoricoxib in a low dose treatment regimen as novel therapy strategy.

Indication of Source: 1. Langhammer S and Scheerer J. Oncotarget 8, 43555-43570 (2017).

Citation Format: Dennis Gürgen, Theresia Conrad, Michael Becker, Susanne Sebens, Christoph Röcken, Jens Hoffmann, Stefan Langhammer. Breaking the crosstalk of the cellular tumorigenic network in NSCLC by a highly effective drug combination [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 3095.

Abstract 1650: Humanized mouse models for preclinical evaluation of novel immune cell therapies, checkpoint inhibitors, and immune cell engagers

Background The preclinical evaluation of novel immune therapies demands humanized mouse models with functional human immune cells. In previous studies we have demonstrated, that either peripheral blood mononuclear cells (PBMC), subsets of PBMCs like T- and NK-cells or hematopoietic stem cells (HSC) can be used to establish a humanized immune system with functional T-, B-, and NK cells, as well as monocytes and dendritic cells in immunodeficient mice. By transplantation of cell-line-derived (CDX) or patient-derived (PDX) tumor xenografts on humanized mice, we successfully generated a full human tumor-immune-cell model for different tumor entities. Finally, we validated the functionality of these models using checkpoint inhibitors like Ipilimumab (Ipi), Nivolumab (Nivo), Pembrolizumab (Pembro), cell therapies and immune cell engagers.

Methods HSC-humanized mice were generated by i.v. transplantation of CD34+stem cells to immunodeficient NOG mice. PBMC or isolated T- or NK-cell preparations were used to humanize mice by single or multiple i.v. injections. CDX and PDX from different entities (i.e. lymphoma, neuroblastoma, and breast cancer) were transplanted on those humanized mice. These models were used to evaluate novel immune therapies. Blood and tumor samples were analysed by FACS for immune cell infiltration and activation.

Results The transplanted HSCs engrafted in mice and established a functional human immune system with proliferation and differentiation. 14 weeks after HSC inoculation up to 20% of the human immune cells in the blood were functional T-cells, characterized by a high PD-1 expression. The selected CDX and PDX tumors successfully engrafted on humanized mice without significant differences in tumor growth compared to non-humanized mice. Checkpoint inhibitor treatments induced tumor growth delay in selected models. FACS analysis of tumors revealed an increased percentage of tumor infiltrating T-cells. We identified a set of CDX and PDX models without interference with parallel injection of PBMC, T- or NK-cell preparations for the evaluation of immune cell engagers and other cell therapies.

Conclusions We established human tumor-immune-cell models of different entities using CDX or PDX in combination with different donor derived immune cell subsets as effector cells. We demonstrated successful engraftment of HSC on immunodeficient mouse strains, generating mice with a functional human hematopoiesis. These models have been employed for preclinical evaluation of novel checkpoint inhibitors, cell therapies and immune cell engagers. Our models allow preclinical, translational studies on tumor immune biology as well as evaluation of new therapies, drug combinations and biomarker identification and validation.

Citation Format: Maria Stecklum, Annika Wulf-Goldenberg, Bernadette Brzezicha, Wolfgang Walther, Jens Hoffmann. Humanized mouse models for preclinical evaluation of novel immune cell therapies, checkpoint inhibitors, and immune cell engagers [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 1650.

INSP-15. ITCC-P4: A sustainable platform of molecularly well-characterized PDX models of pediatric cancers for high throughputin vivo testing

Thanks to state-of-the-art molecular profiling techniques we by now have a much better understanding of pediatric cancers and what is driving them. On the other hand, we have also realized that pediatric cancers are much more heterogeneous than previously thought. Many new types and subtypes of pediatric cancers have been identified with distinct molecular and clinical characteristics. However, for many if not most of these new types and subtypes there is no specific treatment available, yet. In order to develop specific treatment protocols and to increase survival rates for pediatric cancer patients further, both at diagnosis and relapse/metastasis, we need a large collection of well-characterized preclinical models representing all the different types and subtypes. These models can be used for preclinical drug testing to prioritize the pediatric development of anticancer drugs that would be best targeting pediatric tumor biology. The ITCC-P4 consortium, which is a collaboration between many academic centers across Europe, several companies involved in in vivo preclinical testing, and ten pharmaceutical companies, started in 2017 with the overall aim to establish a sustainable platform of >400 molecularly well-characterized PDX models of high-risk pediatric cancers and to use them for in vivo testing of novel mechanism-of-action based treatments. Currently, 340 models have been fully established, including 87 brain tumor models and 253 non-brain tumor models, together representing many different tumor types both from primary and relapsed/metastatic disease. Out of these 340 models, 252 have been fully molecularly characterized, most of them together with their matching original tumors, and almost of all these models are currently being subjected to in vivo testing using three standard of care drugs and six novel mechanism-of-action based drugs. In this presentation, an update on the current status of the ITCC-P4 platform and the data we collectively have generated thus far will be presented.

Calcium-binding protein S100P is a new target gene of MACC1, drives colorectal cancer metastasis and serves as a prognostic biomarker

Background

The metastasis inducing gene MACC1 is a prognostic and predictive biomarker for metastasis in several cancers. Its mechanism of inducing metastasis includes the transcriptional control of other cancer-related target genes. Here, we investigate the interplay with the metastasis driver S100P in CRC progression.

Methods

MACC1-dependent S100P expression was analysed by qRT-PCR. The binding of MACC1 to the S100P promoter was determined by ChIP. Alterations in cell proliferation and motility were determined by functional in vitro assays. In vivo metastasis after intrasplenic transplantation was assessed by bioluminescence imaging and evaluation of tumour growth and liver metastasis. The prognostic value of S100P was determined in CRC patients by ROC-based Kaplan–Meier analyses.

Results

Expression of S100P and MACC1 correlated positively in CRC cells and colorectal tumours. MACC1 was found binding to the S100P promoter and induces its expression. The overexpression of S100P increased proliferation, migration and invasion in vitro and significantly induced liver metastasis in vivo. S100P expression was significantly elevated in metachronously metastasising CRC and was associated with shorter metastasis-free survival.

Conclusions

We identified S100P as a transcriptional target gene of MACC1. Expression of S100P increases the metastatic potential of CRC cells in vitro and in vivo, and serves as a prognostic biomarker for metastasis-free survival of CRC patients, emphasising novel therapeutic interventions targeting S100P.

Breaking the crosstalk of the Cellular Tumorigenic Network by low-dose combination therapy in lung cancer patient-derived xenografts

Non-small cell lung cancer (NSCLC) is commonly diagnosed at advanced stages limiting treatment options. Although, targeted therapy has become integral part of NSCLC treatment therapies often fail to improve patient's prognosis. Based on previously published criteria for selecting drug combinations for overcoming resistances, NSCLC patient-derived xenograft (PDX) tumors were treated with a low dose combination of cabozantinib, afatinib, plerixafor and etoricoxib. All PDX tumors treated, including highly therapy-resistant adeno- and squamous cell carcinomas without targetable oncogenic mutations, were completely suppressed by this drug regimen, leading to an ORR of 81% and a CBR of 100%. The application and safety profile of this low dose therapy regimen was well manageable in the pre-clinical settings. Overall, this study provides evidence of a relationship between active paracrine signaling pathways of the Cellular Tumorigenic Network, which can be effectively targeted by a low-dose multimodal therapy to overcome therapy resistance and improve prognosis of NSCLC.

Suboptimal uptake, retention, and adherence of daily oral PrEP among people with OUD receiving HCV treatment

Background

Daily oral preexposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) prevents human immunodeficiency (HIV) among people who inject drugs (PWID). Despite rising HIV incidence and injection drug use (IDU), PrEP use remains low and there is limited research about uptake, adherence, and retention among PWID.

Methods

The ANCHOR investigation evaluated a community-based care model collocating hepatitis C virus (HCV) treatment, medication for opioid use disorder (OUD), and PrEP in individuals in Washington, DC, and Baltimore, Maryland. PrEP counseling was conducted from HCV treatment day 0 until week 24. Subjects could start any time during this window, were followed for 48 weeks, and were assessed for adherence by self-report and dried blood spot TDF analysis.

Results

One hundred ninety-eight participants were enrolled, of whom 185 (93%) were HIV negative. Twenty-nine individuals (15.7% of HIV-negative cohort) initiated PrEP. One hundred sixteen participants (62.7%) met 2014 Centers for Disease Control and Prevention (CDC) PrEP criteria due to IDU (82 [44.3%]), sex (9 [4.9%]), or both practices (25 [13.5%]). Providers recommended PrEP to 94 individuals (50.8%), and recommendation was associated with PrEP uptake. Median treatment duration was 104 days (interquartile range, 28–276 days), with 8 participants retained through week 48. Adherence was variable over time by self-report and declined by TDF analysis. No HIV seroconversions occurred.

Conclusions

This cohort of people with HCV and OUD experienced low uptake of PrEP despite the majority meeting CDC criteria. High rates of disruption and discontinuation, compounded by variable adherence, made TDF/FTC a suboptimal prevention strategy. Emerging modalities like long-acting formulations may address these barriers, but PWID have been excluded from their development to date.

Rapid testing of candidate oncogenes and tumour suppressor genes in signal transduction and neoplastic transformation

The COSMIC database (version 94) lists 576 genes in the Cancer Gene Census which have a defined function as drivers of malignancy (oncogenes) or as tumour suppressors (Tier 1). In addition, there are 147 genes with similar functions, but which are less well characterised (Tier 2). Furthermore, next-generation sequencing projects in the context of precision oncology activities are constantly discovering new ones. Since cancer genes differ from their wild-type precursors in numerous molecular and biochemical properties and exert significant differential effects on downstream processes, simple assays that can uncover oncogenic or anti-oncogenic functionality are desirable and may precede more sophisticated analyses. We describe simple functional assays for PTPN11 (protein-tyrosine phosphatase, non-receptor-type 11)/SHP2 mutants, which are typically found in RASopathies and exhibit potential oncogenic activity. We have also designed a functional test for lysyl oxidase (LOX), a prototypical class II tumour suppressor gene whose loss of function may contribute to neoplastic transformation by RAS oncogenes. Moreover, we applied this test to analyse three co-regulated, RAS-responsive genes for transformation-suppressive activity. The integration of these tests into systems biology studies will contribute to a better understanding of cellular networks in cancer.

Predictors of perceived pandemic preparedness among general practitioners

Background

General practitioners (GPs) are essential for providing and maintaining health care during a pandemic. Pandemic preparedness (PP) of GPs can play a vital role in their management of a pandemic situation. This study aimed to examine the association stockpiled personal protective equipment (PPE) and knowledge of pandemic plans on perceived PP among German GPs. This analysis is part of the research project COVID-GAMS (Funding code: 01KI2099).

Methods

Three multivariable linear regression models were developed based on an online cross-sectional survey for the period March-April 2020 (the onset of the pandemic in Germany). Data were collected using self-developed items on self-assessed PP and knowledge of a pandemic plan and its utility. The stock of seven PPE items was queried. For PPE items, three different PPE scores were compared. Control variables for all models were gender and age.

Results

508 GPs were included in the study; 65.16% believed that they were very poorly or poorly prepared. Furthermore, 13.83% of GPs were aware of a pandemic plan; 40% rated those plans as beneficial. The stock of FFP-2/3 masks, protective suits, face shields, safety glasses, and medical face masks were mostly considered completely insufficient or insufficient, whereas disposable gloves and disinfectants were considered sufficient or completely sufficient. The stock of PPE was significantly positively associated with PP and had the largest effect on PP across all models; the association of the knowledge of a pandemic plan was significant but considerably smaller. PPE scores did not vary considerably in their explanatory power. The assessment of a pandemic plan as beneficial did not significantly affect PP.

Conclusions

An adequate stockpile of PPE is essential for perceived pandemic preparedness among GPs. Pandemic plans are considered less important for GPs. General practitioners, health authorities, and policy makers should focus on stockpiling PPE for future pandemic emergencies.

Key messages

Sufficient stockpiled personal protective equipment is the most important factor influencing pandemic preparedness of general practitioners in Germany. Knowledge on a pandemic plan has a subordinate effect on pandemic preparedness of general practitioners; usefulness of a pandemic plan does not have a significant effect.

Patterns of cardiac involvement in patients with long COVID syndrome using cardiovascular magnetic resonance

Background

Long COVID (LC) is an increasingly recognized late complication of COVID-19 infection. Cardiovascular involvement has also been implicated, however, the type and extent of the underlying cardiovascular injury remains unknown.

Purpose

To evaluate the association between ongoing symptoms and findings with cardiovascular magnetic resonance (CMR) in consecutive patients recently recovered from COVID-19 illness.

Methods

Prospective observational cohort study of patients recently recovered from COVID-19 illness and no previously known cardiovascular disease were included between April 2020 and April 2021. Demographic characteristics, cardiac blood markers, and CMR imaging a minimum of 4 weeks from the diagnosis were obtained.

Results

Of the 389 included patients, 192 (49%) were male, the mean (±standard deviation) age was 44 (±13) years and 61 (16%) required hospitalization during the acute illness. The median (IQR) time interval between COVID-19 diagnosis and CMR was 94 (71–165) days. 298 (77%) of patients continued to experience ongoing cardiovascular symptoms (long COVID, LC), including dyspnea, palpitations, atypical chest pain and fatigue at the time of CMR at least 4 weeks after the infection. In most patients, the symptoms were only effort related 137 (46%), whereas in 98 (33%) the symptoms affected the activities of daily life; 10 (3%) had severe and debilitating symptoms at rest. Compared to those with no LC (NLC, n=91), LC patients were more commonly hospitalized, had significantly higher native T1, native T2, and showed pericardial enhancement and effusion (Figure 1). There were no differences in cardiac biomarkers, left ventricular (LV) and right ventricular ejection fraction and mass. Proportionally, men and women were similarly affected (n=144 (73%) vs. n=157 (80%), p=0.18). Previous hospitalization was associated with hypertension and ongoing detectable troponin. LC status was associated with previous hospitalization and CMR findings of raised native T1 and native T2, and in females also pericardial enhancement. Severity of symptoms were associated with increased native T1 and T2 and decreased end-diastolic volume, whereas cardiac function showed no significant difference.

Conclusions

In this cohort of patients recently recovered from COVID-19 infection, ongoing cardiovascular symptoms were common. The LC status was related to previous hospitalization and CMR imaging findings of myopericardial inflammation. The extent and type of cardiovascular findings was associated with the severity of symptoms. These findings indicate the need for ongoing investigation of the long-term cardiovascular consequences of COVID-19.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The German Heart Foundation (Deutsche Herzstiftung) and Bayer AG, Leverkusen, Germany

Chronic ischemic heart failure in humans is associated with changes in expression of antigen processing HLA types and activation of T-cells

Background

Sustained pathological inflammation is a hallmark of chronic ischemic heart failure (HF). The short term response to myocardial ischemia has found a protective phenotype for T regulatory cells, yet the extent and consequence of prolonged T-cell activation in chronic ischemic heart failure is unclear.

Methods and results

Single cell RNA sequencing of circulating immune cells (n=181,712 cells) from healthy (n=8) and heart failure donors (n=8) revealed a relative increase in the proportion of activated T cells in heart failure patients relative to healthy controls. T cell activation molecules of the HLA-DR series genes on antigen presenting cells were found to be strongly associated with heart failure patients in the sequencing data, with decreases in antigen processing genes (HLA-DM series) in heart failure patients. Validation via flow cytometry in 27 healthy controls and 43 heart failure patients showed relative decreases of greater than 30% for HLA-DM to HLA-DRB molecule ratios in HF patients (p=0.0082), suggesting an aberrant antigen presentation to T cells linked to autoimmunity in heart failure patients. Additionally, costimulatory molecules such as ICAM-1 (p=0.004) and activation markers like TREM-1 (p=0.04) were elevated in circulating monocytes cells, which may potentiate T cell activation. Correspondingly, a significant and striking decrease in CD4+ and CD8+ naïve T cells along with increases in combined effector memory and TEMRA cells could be evidenced in heart failure patients. Levels of the T-cell homing marker CCR5 were elevated in patients with heart failure. To gain additional insights into potential functional consequences in the heart, supernatants from 3h LPS stimulated immune cells (peripheral blood mononuclear cells or T cells) were applied to various vascular cell types (endothelial cells, pericytes) and with cardiac organoids for 48h. Apoptosis was increased more than 3 fold following incubation with media derived from peripheral blood cells of HF patients, suggesting that immune cells from heart failure patients can directly and indirectly impair cardiovascular cells.

Conclusion

Heart failure is marked by sustained increases in relative proportions of effector T cell and TEMRA populations and homing markers suggesting these cells may undergo extravasation to tissues and deteriorate inflamed myocardium - hastening heart failure progression, worsening prognosis. Further research is required to assess how these cells may migrate to myocardial tissues and what interventions could be useful for blocking myocardial damage.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): DZHK, DGK, SFB

Photogrammetric evaluation of corrective surgery for trigonocephaly

The aim of this study was to capture preoperative, postoperative, and follow-up head shapes of male trigonocephaly patients who underwent fronto-orbital remodelling (FOR), using three-dimensional (3D) photography. Fifty-seven male infants with metopic synostosis operated on using standardized FOR during a 5-year period were included. All measurements were compared with those of an age-matched healthy control cohort (n = 253 for early postoperative comparison, n = 43 for the 1-year follow-up comparison) to determine the effect of FOR at 14 days and at 1 year post-surgery. Intracranial volume, frontal angle, nasofrontal angle, interfrontoparietal-interparietal ratio, and inter-orbital distances were measured 1 day preoperatively, 14 days and 1 year postoperatively. Mean age at surgery was 9.7 ± 1.1 months. Prior to surgery, boys with metopic synostosis showed a reduced intracranial volume (-7.0%, P < 0.001), frontal angle (-10.2%, P < 0.001), interfrontoparietal-interparietal ratio (-4.9%, P < 0.01), and orbital distances (-6.5%, P < 0.001) compared to the reference group, but values did not differ significantly from the specific control group after surgery (all P> 0.05). This was consistent by the time of the follow-up examination. Corrective surgery should therefore aim to achieve volume expansion and correction of the deformity. Furthermore, 3D photogrammetry provides a valuable alternative to computed tomography scans in the diagnosis of metopic synostosis, significantly reducing the amount of radiation exposure to the brain.

Abstract 3020: Human leukocyte antigen (HLA) typing of a broad panel of cancer patient-derived xenograft (PDX) models for immune therapies

Background In immuno-oncology research, an appropriate microenvironment for both human tumor cells and human immune cells is an important but challenging factor for successful development of relevant preclinical models. Humanized patient-derived xenograft (PDX) models can support establishment of such an environment based on matching human leukocyte antigen (HLA) profiles of PDX and compatible human immune cell populations. In this study, we determined the individual HLA types of a broad panel of 291 established PDX models from 18 different tumor entities. Furthermore, we performed comprehensive HLA matching analyses of all PDX models and 13 peripheral blood mononuclear cell (PBMC) donors to enable personalized studies with HLA-matched PDX.

Methods The HLA profile of each PDX was determined comprising HLA class I, II and non-class types in 4-digit resolution. Matching analyses were performed according to donor-recipient HLA matching criteria recommended by the Blood and Marrow Transplant Clinical Trials Network (BMT CTN). For comparative HLA profile analyses, allele frequencies of 8862 German stem cell donors provided by The Allele Frequency Net Database were downloaded.

Results The individual HLA profiles of all PDX models were generated comprising HLA-A, -B and -C (class I), HLA-DQA1, -DQB1, -DRB1, -DPA1 and -DPB1 (class II) as well as HLA-H (non-class) types. Comparative analyses of HLA profiles revealed that obtained frequencies of PDX HLA alleles are comparable with frequencies of a representative population of 8862 German stem cell donors. HLA profile matching analyses performed for all PDX models and PBMC donors resulted in 15 matches regarding PDX from head and neck, lung, mammary and pancreatic carcinoma as well as from endometrial cancer, glioma, lymphoma, melanoma and sarcoma. Dependence of immune therapy efficacy on matched HLA profiles was shown exemplarily for a head and neck squamous cell cancer (HNSCC) PDX. The HNSCC PDX was humanized with PBMC from 5 donors representing different degrees of HLA matching (33 - 100 %). Treatment with the checkpoint inhibitor Nivolumab caused a more powerful tumor growth inhibition in matched HLA profiles compared to non-matched profiles. This indicated a relation between antitumoral immune therapy effect and HLA matching in preclinical models.

Conclusions We generated a comprehensive HLA profile portfolio containing information of a broad panel of PDX models. Matched HLA profiles of PDX models and PBMC donors enable personalized, preclinical immune-oncology studies to support the development of novel therapeutic strategies.

Citation Format: Theresia Conrad, Annika Wulf-Goldenberg, Maria Stecklum, Michael Becker, Konrad Klinghammer, Jens Hoffmann. Human leukocyte antigen (HLA) typing of a broad panel of cancer patient-derived xenograft (PDX) models for immune therapies [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 3020.

Subclinical tuberculosis and adverse infant outcomes in pregnant women with HIV

BACKGROUND: Tuberculosis (TB) in pregnant women with HIV is associated with adverse maternal and infant outcomes. Previous studies have described a substantial prevalence of subclinical TB in this group, but little is known about the impact of subclinical TB on maternal and pediatric outcomes.METHODS: The Tshepiso Study recruited 235 HIV-infected pregnant women with TB (and matched HIV-positive, TB-negative pregnant controls), in Soweto, South Africa, from 2011 to 2014. During enrolment screening, some women initially recruited as controls were subsequently diagnosed with prevalent TB. We therefore assessed the prevalence of subclinical TB, associated participant characteristics and outcomes.RESULTS: Of 162 women initially recruited as TB-negative controls, seven (4.3%) were found to have TB on sputum culture. All seven had negative WHO symptom screens, and six (86%) were smear-negative. Of their seven infants, one was diagnosed with TB, and three (43%) experienced complications compared to zero infants with TB and 11% experiencing complications in the control group of TB-negative mothers (P = 0.045).CONCLUSION: We discovered an appreciable prevalence of subclinical TB in HIV-infected pregnant women in Soweto, which had not been detected by screening algorithms based solely on symptoms. Infants of HIV-infected mothers with subclinical TB appear to have a higher risk of adverse outcomes than those of TB-negative mothers.

[A man with groin pain]

A 78-year-old man was evaluated at the outpatient orthopaedic clinic with progressive pain in the right groin. X-ray revealed osteoarthritis of the right hip and fibrous dysplasia of the proximal femur. Total hip arthroplasty was performed using a cemented long-stem femoral component spanning the entire lesion.

Advanced calibration kit for scanning microwave microscope: Design, fabrication, and measurement

We present in this paper a new design of a capacitive calibration kit for scanning microwave microscopy (SMM). As demonstrated by finite element modelings, the produced devices are highly independent of material parameters due to their lateral configuration. The fabrication of these gold-based structures is realized by using well established clean-room techniques. SMM measurements are performed under different conditions, and all capacitive structures exhibit a strong contrast with respect to the non-capacitive background. The obtained experimental data are employed to calibrate the used SMM tips and to extract the capacitance of produced devices following a method based on the short-open-load calibration algorithm for one-port vector network analyzers. The comparison of experimental capacitance and nominal values provided by our models proves the applicability of the used calibration approach for a wide frequency range.

Mutation-specific effects of NRAS oncogenes in colorectal cancer cells

In colorectal cancer (CRC), the prevalence of NRAS mutations (5-9%) is inferior to that of KRAS mutations (40-50%). NRAS mutations feature lately during tumour progression and drive resistance to anti-EGFR therapy in KRAS wild-type tumours. To elucidate specific functions of NRAS mutations in CRC, we expressed doxycycline-inducible G12D and Q61K mutations in the CRC cell line Caco-2. A focused phospho-proteome analysis based on the Bio-Plex platform, which interrogated the activity of MAPK, PI3K, mTOR, STAT, p38, JNK and ATF2, did not reveal significant differences between Caco-2 cells expressing NRAS^G12D, NRAS^Q61K and KRAS^G12V. However, phenotypic read-outs were different. The NRAS Q61K mutation promoted anchorage-independent proliferation and tumorigenicity, similar to features driven by canonical KRAS mutations. In contrast, expression of NRAS^G12D resulted in reduced proliferation and apoptosis. At the transcriptome level, we saw upregulation of cytokines and chemokines. IL1A, IL11, CXCL8 (IL-8) and CCL20 exhibited enhanced secretion into the culture medium. In addition, RNA sequencing results indicated activation of the IL1-, JAK/STAT-, NFκB- and TNFα signalling pathways. These results form the basis for an NRAS^G12D-driven inflammatory phenotype in CRC.

Inhibiting phosphoglycerate dehydrogenase counteracts chemotherapeutic efficacy against MYCN-amplified neuroblastoma

Here we sought metabolic alterations specifically associated with MYCN amplification as nodes to indirectly target the MYCN oncogene. Liquid chromatography-mass spectrometry-based proteomics identified seven proteins consistently correlated with MYCN in proteomes from 49 neuroblastoma biopsies and 13 cell lines. Among these was phosphoglycerate dehydrogenase (PHGDH), the rate-limiting enzyme in de novo serine synthesis. MYCN associated with two regions in the PHGDH promoter, supporting transcriptional PHGDH regulation by MYCN. Pulsed stable isotope-resolved metabolomics utilizing ¹³ C-glucose labeling demonstrated higher de novo serine synthesis in MYCN-amplified cells compared to cells with diploid MYCN. An independence of MYCN-amplified cells from exogenous serine and glycine was demonstrated by serine and glycine starvation, which attenuated nucleotide pools and proliferation only in cells with diploid MYCN but did not diminish these endpoints in MYCN-amplified cells. Proliferation was attenuated in MYCN-amplified cells by CRISPR/Cas9-mediated PHGDH knockout or treatment with PHGDH small molecule inhibitors without affecting cell viability. PHGDH inhibitors administered as single-agent therapy to NOG mice harboring patient-derived MYCN-amplified neuroblastoma xenografts slowed tumor growth. However, combining a PHGDH inhibitor with the standard-of-care chemotherapy drug, cisplatin, revealed antagonism of chemotherapy efficacy in vivo. Emergence of chemotherapy resistance was confirmed in the genetic PHGDH knockout model in vitro. Altogether, PHGDH knockout or inhibition by small molecules consistently slows proliferation, but stops short of killing the cells, which then establish resistance to classical chemotherapy. Although PHGDH inhibition with small molecules has produced encouraging results in other preclinical cancer models, this approach has limited attractiveness for patients with neuroblastoma.

Myocardial infarction triggers Inflammatory deterioration of vascular niche by accelerating loss of a specific vessel subtype in bone

Introduction

The interface between heart and bone emerges as a key trigger of post-infarction inflammation and progression of chronic heart failure (CHF). However, our knowledge on the underlying mechanisms of this interaction is incomplete. Bone vasculature, specifically so-called H-type (Endomucinhigh) endothelial cells (EC), plays a crucial role in maintenance of the bone integrity and regulation of hematopoietic stem cells (HSC). While previous studies in mice showed the reduction of H-type vessels by aging, the impact of ischemic heart disease is unclear. Therefore, we aimed to investigate the effects of myocardial infarction (MI) and chronic heart failure on the vascular bone cell composition in mice and humans.

Methods and results

Flow cytometric analysis of harvested bones at the different timepoints after MI induction in mice revealed a gradual loss of H-type endothelial cells in the time-course of developing chronic heart failure (P&lt;0.05 at day 7 and 14 vs. control; P&lt;0.0001 at day 28 vs. control). This results were confirmed in immunostainings of tibia sections showing a significant decrease of H-type vessel length after MI (p&lt;0.05 at day 14 and 28, accordingly). The loss of type-H endothelium was accompanied by a significant expansion of long-term HSC in the bone (P=0.0005 at day 28 post MI vs. control). Importantly, type H ECs were also significantly reduced in the bone of ischemic post-infarct HF patients (n=16) compared with control subjects (n=8; P=0.0003). To gain insights into the mechanisms underlying the changes in the vascular niche, we performed single cells RNA sequencing of human BM ECs. These studies confirmed the decrease in Emcnexpressing ECs in ischemic HF patients, which was accompanied by significantly increased expression of inflammatory genes, including IL1b (P&lt;0.0001). Inflammatory EC phenotypes and IL1b expression in HF could be further confirmed at protein level using cytospin immunostainings. Murine studies further revealed an early induction IL-1b specifically in H-type vessels already at day 1 after MI induction, which preceded the loss of H-type endothelium within the following 4 weeks. By inhibiting IL-1b production using a specific Nlrp3 inflammasome inhibitor (MCC950) we could observe a partial restoration of H-type EC frequencies (P=0.033) and a significant increase in H-type vessel length (p=0.035) at day 28 day after MI.

Conclusions

Our data show for the first time an impact of myocardial infarction and chronic heart failure on the bone marrow vasculature. These changes seem to be strongly associated with inflammatory response in H-type vessels, which precedes its loss after MI. Specifically, the induction of the inflammatory cytokine IL1b may contribute to the disturbed phenotype. This suggest that inhibition of IL1b (e.g. by canakinumab) be used as a novel strategy to prevent or reverse the deterioration of the vascular bone function in ischemic heart disease.

Funding Acknowledgement

Type of funding source: None

DNMT3A clonal hematopoiesis-driver mutations are associated with profound changes in monocyte and T cell signatures in humans with heart failure

Background

Clonal hematopoiesis (CH) driven by mutations of DNA methyltransferase 3a (DNMT3A) is associated with increased incidence of cardiovascular disease and poor prognosis of patients with chronic heart failure (HF) and aortic stenosis. Although experimental studies suggest that DNMT3A CH-driver mutations may enhance inflammation, specific signatures of inflammatory cells in humans are missing. Single-cell RNA-sequencing provides a novel opportunity to define subsets of immune cells mediating inflammation in humans.

Methods

Transcriptomic profiles of peripheral blood mononuclear cells were analysed in N=6 HF patients harboring DNMT3A CH-drived mutations and with HF and N=5 patients with HF and DNMT3A mutations by single-cell RNA-sequencing.

Results

Monocytes of HF patients carrying DNMT3A mutations demonstrated a significantly increased expression of inflammatory genes compared to monocytes derived from patients with HF without DNMT3A mutations. Among the specific up-regulated genes were the prototypic inflammatory interleukins (IL) IL1B, IL6, and IL8, the macrophage inflammatory proteins CCL3 and CCL4 as well as restin, which augments monocyte-endothelial adhesion. The classical monocyte subset of DNMT3A mutation carriers showed increased expression of immunoglobulin superfamily members CD80, CD300LB, and SIGLEC12, as well as the cell adhesion molecule CD58, all of which may be involved in monocyte-T cell interactions. DNMT3A mutation carriers were further characterized by increased expression of T cell receptor chains and Th1, Th17, CD8+ and Treg specific signatures.

Conclusions

This study demonstrates that circulating monocytes and T cells of HF patients harboring CHIP-driver mutations in DNMT3A exhibit a highly inflamed transcriptome, which may contribute to the aggravation of chronic heart failure.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): The German Research Foundation (SFB834, Project B1), and the German Center for Cardiovascular Research (DZHK).

Long telomere length in circulating leukocytes is associated with monocytosis and poorer survival in patients with transcatheter aortic valve replacement

Background

Whiletranscatheter aortic valve replacement (TAVR) has become a standard treatment option in the management of patients with severe aortic stenosis and higher risk for cardiac surgery, occurrence of a systemic inflammatory response after TAVR limits patients' prognosis. Leukocyte telomere length (LTL) is an established marker of cellular senescence and longer telomeres are hallmarks of immune competence and inflammatory responsiveness of leukocyte subsets. In the present study, we assessed LTL and its impact on 2-year survival in patients (pts) following TAVR.

Methods and results

LTL was analyzed using quantitative real-time PCR in 285 consecutive pts (mean age 80.9 years, 49% male) undergoing TAVR and correlated with 2-year all-cause mortality (46 deaths, 16%). Kaplan-Meier survival curves showed that the highest compared to lowest tertile of LTL was associated with an increased rate of all-cause mortality (log rank p=0.03). Multivariate regression model revealed higher EuroSCORE 2 (HR: 1.03, 95% CI: 1.01–1.05; p=0.021) and long LTL (HR: 1.001, 95% CI: 1.001–1.001; p=0.023) to be independent predictors for 2-year mortality, after adjustment for clinical variables such as age, sex, cardiovascular risk factors, LVEF and renal function. When analyzing blood leukocyte subset composition, pts in the highest LTL tertile showed significantly higher levels of circulating neutrophils (p=0.011) and monocytes (p=0.011), whereas there was no significant correlation between LTL and lymphocyte counts (p=0.12).

Conclusion

In elderly patients with severe aortic valve stenosis, long leukocyte telomere length is associated with increased mortality after TAVR. This might be explained by enhanced immune competence and increased pro-inflammatory leukocyte function in these patients as indicated by significant monocytosis, which might drive systemic inflammatory response syndrome or chronic inflammation and limit the prognosis in TAVR patients.

Funding Acknowledgement

Type of funding source: None

Preserved Th2 lymphocytes improve prognosis of diabetic patients undergoing TAVR

Introduction

Previous studies have shown that presence of diabetes (DM) worsens outcome of patients after transfemoral aortic valve (TAVR). DM has been associated with pathological T-lymphocyte (T-cell) polarization, marked by decreased anti-inflammatory Th2 cells and increased pro-inflammatory Th1 cells. However, the risk-modulatory impact of T-cell polarization in diabetic patients with severe aortic stenosis has not been shown thus far. In this study we assessed the role of T-cell subsets in diabetic patients undergoing TAVR.

Methods and results

A total of 129 patients (76% male, median age [IQR]: 83 years [79–86]) admitted for TAVR at the University Clinic Frankfurt were enrolled. The patients were evaluated using classical risk scores and the Th1/Th2 T-cell polarization was assessed using flow cytometry. The endpoint of the study was all-cause death. Kaplan-Meier survival, ROC curve analysis and Mann-Whitney-U-Test were used in statistical analysis. The differences were considered significant by error probability p&lt;0.05. Twenty-six patients died within follow up of 274 (188–367) days. The conventional risk parameters were distributed as follows: STS score: 3.45 (2.47–4.97), LVEF: 60% (45–65), CRP: 0.33 mg/dl (0.15–0.79), hsTropT: 24.5 pg/ml (16.5–40.0), IL6: 6.7 pg/ml (4.1–12.2), Hb: 12.3 g/dl (11.00–13,75), Creatinine: 1.15 mg/dl (0.93–1.54), Th1 cells = 79.88 cells/μl (55.69–122.16), Th2 cells: 25.31 cells/μl (19.69–38.33), NT-proBNP: 2033 pg/ml (1076–5531). All these parameters were associated with mortality. Hence, only Hb (AUC=0.761), NT-proBNP (AUC=0.726), Th2 cells (AUC=0.712) and STS score (AUC=0.737) provided AUC&gt;0.7. Diabetes was revealed to be significantly associated with mortality in patients with and without DM (15/48 (31%) vs. 11/81 (14%), respectively, P=0.019). There were no significant differences in the counts of Th-cell subsets between diabetic and non-diabetic patients (Th1 (90.95 (62.41–154.22) vs 76.36 (53.16–100.49), P=0.072); Th2 (29.18 (20.13–43.77) vs 24.74 (20.27- 35.11), p=0.245), for DM and non-DM respectively). However, the survival rate in patients with DM and Th2 cell counts higher than or equal to the calculated optimal cut-off of 24.3 cells/μl was comparable with patients without DM (25/28 (89%) vs. 36/38 (95%), p=0.453). In contrast, diabetic patients with reduced Th2 cells (&lt;24.3 cells/μl) were much more likely to die (10/15 (67%) vs. 8/34 (24%), p=0.003, patients with DM and without, respectively).

Conclusion

Our results show for the first time a risk-modulatory impact of T-cell immunity in diabetic patients with severe degenerative aortic stenosis. Reduced Th2 cells are strongly associated with mortality in patients considered for TAVR and significantly deteriorate prognosis in patients with concomitant diabetes.

Funding Acknowledgement

Type of funding source: None

Combination of copanlisib with cetuximab improves tumor response in cetuximab-resistant patient-derived xenografts of head and neck cancer

Despite recent advances, the treatment of head and neck squamous cell carcinoma (HNSCC) remains an area of high unmet medical need. HNSCC is frequently associated with either amplification or mutational changes in the PI3K pathway, making PI3K an attractive target particularly in cetuximab-resistant tumors. Here, we explored the antitumor activity of the selective, pan-class I PI3K inhibitor copanlisib with predominant activity towards PI3Kα and δ in monotherapy and in combination with cetuximab using a mouse clinical trial set-up with 33 patient-derived xenograft (PDX) models with known HPV and PI3K mutational status and available data on cetuximab sensitivity. Treatment with copanlisib alone resulted in moderate antitumor activity with 12/33 PDX models showing either tumor stabilization or regression. Combination treatment with copanlisib and cetuximab was superior to either of the monotherapies alone in the majority of the models (21/33), and the effect was particularly pronounced in cetuximab-resistant tumors (14/16). While no correlation was observed between PI3K mutation status and response to either cetuximab or copanlisib, increased PI3K signaling activity evaluated through gene expression profiling showed a positive correlation with response to copanlisib. Together, these data support further investigation of PI3K inhibition in HNSCC and suggests gene expression patterns associated with PI3K signaling as a potential biomarker for predicting treatment responses.

Feasibility of precise and reliable glucose quantification in human whole blood samples by 1 tesla benchtop NMR

The standard procedure for blood glucose measurements is enzymatic testing. This method is cheap, but requires small samples of open blood with direct contact to the test medium. In principle, NMR provides non-contact analysis of body fluids, but high-field spectrometers are expensive and cannot be easily utilized under clinical conditions. Low-field NMR systems with permanent magnets are becoming increasingly smaller and more affordable. The studies presented here aim at exploring the capabilities of low-field NMR for measuring glucose concentrations in whole blood. For this purpose, a modern 1 T benchtop NMR spectrometer was used. Challenges arise from broad spectral lines, the glucose peak locations close to the water signal, low SNR and the interference with signals from other blood components. Whole blood as a sample comprises even more boundary conditions: crucial for reliable results are avoiding the separation of plasma and cells by gravitation and reliable reference values. First, the accuracy of glucose levels measured by NMR was tested using aqueous glucose solutions and commercially available bovine plasma. Then, 117 blood samples from oral glucose tolerance testing were measured with minimal preparation by simple pulse-acquire NMR experiments. The analysis itself is the key to achieve high precision, so several approaches were investigated: peak integration, orthogonal projection to latent structure analysis and support vector machine regression. Correlations between results from the NMR spectra and the routine laboratory automated analyzer revealed an RMSE of 7.90 mg/dL for the best model. 91.5% of the model output lies within the limits of the German Medical Association guidelines, which require the glucose measurement to be within 11% of the reference method. It is concluded that spectral quantification of glucose in whole blood samples by high-quality NMR spectrometers operating at 1 T is feasible with sufficient accuracy.

Abstract 1674: Correlation of the mutational pattern and gene expression data of patient-derived Non-Hodgkin lymphoma xenografts (PDX) with the response to targeted therapies

Non-Hodgkin lymphomas (NHL) are lymphoid malignant neoplasms that represent a very heterogeneous group and still pose an important clinical challenge. In particular, the frequent development of resistance to the treatment with standard-of-care (SoC) drugs is associated with a high incidence of disease recurrence. Recent progress in molecular high-throughput profiling has helped to identify genetic drivers for many subtypes of B-cell lymphomas as well as T-cell lymphomas. Target validation and drug development depend on corresponding preclinical models representing the different subtypes. Therefore, we established and characterized a panel of patient-derived NHL xenografts. All lymphoma PDX were derived from peripheral blood, lymph node extirpations or core needle biopsies, respectively, and were routinely implanted subcutaneously into immunodeficient mice. For further characterization, established lymphoma PDX models were treated with SoC (e.g., cyclophosphamide, doxorubicine, vincristine, etoposide) and investigational drugs. To gain a deeper insight into the molecular biology of the lymphoma models, RNA sequencing was performed. More than 20 PDX models from different NHL entities have been successfully established and characterized. We observed heterogeneous individual responses to the SoC treatments as well as to target treatments such as rituximab or ibrutinib. Explorative analysis of RNA sequencing data confirmed the representation of the clinical lymphoma subgroups (e.g. DLBCL, Burkitt, AITL) in our panel of lymphoma models. Based on the RNA sequencing data, the individual Human Leukocyte Antigen (HLA) type of each lymphoma PDX was determined with the aim to enable personalized, HLA type-specific studies. Our lymphoma PDX portfolio provides an exceptional platform for the identification and validation of new targets and allows the preclinical screening of new combinations in translational research projects.

Citation Format: Bernadette Brzezicha, Theresia Conrad, Michael Becker, Aitomi Bittner, Martin Janz, Clemens A. Schmitt, Ulrich Keilholz, Jens Hoffmann. Correlation of the mutational pattern and gene expression data of patient-derived Non-Hodgkin lymphoma xenografts (PDX) with the response to targeted therapies [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1674.

Abstract 5059: Breast cancer patient-derived xenograft models for pre- and co-clinical investigation of immune based therapies

Breast cancer is a highly heterogeneous disease, with a heterogeneous prognosis. Patient-derived xenograft models (PDX) can reflect this heterogeneity and can be used to support the development of novel therapeutic strategies against breast cancer. Preclinical experiments with larger cohorts of breast cancer PDX can be used to model a clinical phase II study with new drugs or drug combinations. The predictive value of these preclinical trials is currently evaluated in co-clinical trials, where treatment effects are compared between patients and their corresponding PDX. We present results from our translational pre- and co-clinical studies in breast cancer immune therapy.

As part of the EFRE-POP Project, we established PDX by collecting breast cancer tissue samples from surgery and engrafting them on immunodeficient mice. The tissues were obtained from patients with disease progression after chemotherapy with three to four drugs. PDXs have been successfully engrafted, phenotypically characterized and drug-screened. The PDXs were tested for response to the standard of care therapies. The staining for estrogen/progesterone/androgen/Her2 receptors, Ki-67, and CK5/6 of the original tumor and the PDX were comparable. The patient tumors and the breast cancer PDX models were further analyzed for the expression of PD-L1. We identified four patients that had received PD-1 or PD-L1 antibodies after a sample (used to establish a corresponding PDX) was obtained.

To evaluate the response of our preclinical PDX models to immune checkpoint inhibitors, we engrafted mice with a human immune system either by transplanting allogeneic hematopoietic stem cells (HSC) or allogenic PBMC's from healthy donors. Besides, we were able to obtain PBMC's from the patients to set up an autologous model. The patient-derived tumors were transplanted to these humanized mice and after successful engraftment treated with the PD-1 or PD-L1 antibodies corresponding with the clinical treatment of the patient.

In summary, humanized PDX of refractory tumors have been established and the first pre-clinical evaluation of response to immune therapy provides evidence that xenografts respond in a qualitatively similar manner as the patient. This suggests a translational relevance of the described pre-clinical models.

Citation Format: Annika Wulf-Goldenberg, Verena Kiver, Maria Stecklum, Bernadette Brzezicha, Philipp Jurmeister, Caroline Schweiger, Jens-Uwe Blohmer, Ulrich Keilholz, Jens Hoffmann. Breast cancer patient-derived xenograft models for pre- and co-clinical investigation of immune based therapies [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5059.

Abstract 6318: Acquired resistance in a malignant pleural mesothelioma preclinical model after treatment with Anetumab ravtansine

Mesothelin (MSLN) is a cell surface glycoprotein with high expression in various cancers and only limited expression in normal tissues. It is expressed in the majority of malignant pleural mesothelioma (MPM), a rare but very aggressive disease. Thus, several anti-MSLN-directed therapies including antibody-drug conjugates (ADCs), immunotoxins, targeted thorium-227 conjugates (TTCs), and CAR-T are currently being explored in MPM and further cancer indications. We developed an anti-mesothelin antibody-drug conjugate, anetumab ravtansine (BAY 94-9343, ARav) in which the anti-MSLN antibody is conjugated via an SPDB linker to the microtubule disrupting payload DM4, a derivative of maytansine. In order to explore potential mechanisms of acquired resistance to treatment with ARav in MPM, the cell line-derived MSLN-positive tumor model NCI-H226 was selected. We had previously shown that this model expresses high levels of MSLN and that ARav dosed for two cycles with 11.2 mg/kg Q3Dx3 inhibited tumor growth by 94% as compared to the vehicle control and achieved a 63% response rate (partial regression in 5 out of 8 mice). NCI-H226 xenograft tumors were transplanted subcutaneously onto mice and treated with 10 mg/kg ARav Q3Dx3 for 3 cycles. A tumor on one mouse that initially responded and afterwards started to regrow despite ARav treatment was excised and tumor tissue was transplanted onto 10 new mice (first in vivo passage). These mice were treated with ARav at 10 mg/kg (Q3Dx3) in the 1rst and 20 mg/kg in the 2nd cycle (n=5; Q3Dx3) or vehicle (n=5). From this approach, 2 tumors (A1, A4) with progressive disease under ARav treatment were obtained. These tumors were each transplanted onto 6 mice (second in vivo passage) which were treated with 20 mg/kg ARav (Q3Dx3) or vehicle. After implantation onto a new host, tumors were not sensitized to ARav treatment indicating that fundamental changes in the tumor cells had happened. To analyze potential molecular changes, tumors from ARav treated and vehicle treated mice were collected and FFPE tumors were analyzed by immunohistochemistry for MSLN and P-gp (MDR1) expression. In addition, MSLN mRNA levels were analyzed by qRT-PCR. In the NCI-H226 tumors serially passaged and with increased growth in the presence of ARav, MSLN protein was reduced to background level when compared to the MSLN Level in freshly established NCI-H226 xenograft tumors. The decrease of MSLN expression was also observed on the RNA level. The experimental data from serial passaging of the NCI-H226 cell line-derived MPM in vivo model with reduced response to ARav show that loss of the MSLN antigen occurs on the mRNA and protein level. Reduction of MSLN expression may decrease binding and internalization of ARav and may thus be a mechanism for acquired resistance in MSLN-expressing tumor models.

Citation Format: Christoph Schatz, Sabine Zitzmann-Kolbe, Reimo Tetzner, Marlen Keil, Jens Hoffmann, Dominik Mumberg, Anette Sommer. Acquired resistance in a malignant pleural mesothelioma preclinical model after treatment with Anetumab ravtansine [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6318.