[Rare combination injury of traumatic spondylolisthesis of the lumbosacral junction and Malgaigne's C3 fracture of the pelvis : Lessons learned]

This article reports on the case of a rare combination injury of a C3 pelvic ring fracture (Malgaigne's fracture) and simultaneous unstable traumatic spondylolisthesis (Meyerding grade 2) of the lumbosacral spine. The patient had pronounced neurological deficits of the lower extremities and tearing of the thecal sac. The selected primary and secondary surgical treatment algorithm of the polytraumatized patient as well as the course are described and critically discussed on the basis of the sparsely available literature.

Abstract 2769: PET imaging shows dose-dependent pharmacokinetics of a 89Zr-labeled mesothelin/CD3 half-life extended bispecific T-cell engager molecule in a syngeneic mouse model

BiTE® (bispecific T cell engager) immune therapy consists of two connected single-chain variable fragments, one targeting T-cells via CD3, and one targeting the tumor via a tumor-associated antigen. Given their short half-life, these molecules are administered by continuous intravenous (iv) infusion to ensure tumor accumulation. To extend plasma half-life, they are conjugated to an Fc domain, resulting in a molecule with an extended pharmacokinetic profile. To evaluate their biodistribution in a syngeneic mouse model, a molecule targeting murine mesothelin and murine CD3 (muMSLN HLE BiTE®), and a non-targeting control HLE BiTE® molecule were radiolabeled with the positron emission tomography (PET) isotope zirconium-89 (89Zr).

METHODS: The control and muMSLN HLE BiTE® were labeled with 89Zr. Immunocompetent BALB/c mice were engrafted in the lower mammary fat pad with mesothelin-positive murine mammary carcinoma cell line 4T1. PET imaging was performed at 1, 3, 5, 7 and 9 days after 50 µg 89Zr-muMSLN HLE BiTE® was administered by iv infusion (n = 8). Next, biodistribution of 10 µg (n = 6), 50 µg (n = 6) and 200 µg 89Zr-muMSLN HLE BiTE® (n = 5) and 50 µg 89Zr-control HLE BiTE® (n = 6) was compared via PET imaging on day 1, 3 and 5. PET-scans were quantified by mean standardized uptake value (SUVmean). Tracer injections were 4 MBq. To compare uptake in multiple groups, an analysis of variance followed by a post-hoc Tukey's multiple comparison test was performed. Values are expressed as mean ± standard deviation.

RESULTS: PET imaging following 50 µg 89Zr-muMSLN HLE BiTE® dosed iv revealed a blood elimination half-life of 63.4 hours. Uptake in tumor, spleen, thymus and liver were visible from 3 days post injection (pi). On day 5, tumor uptake was highest (SUVmean = 1.50 ± 0.2) with a tumor to blood ratio of 1.9 ± 0.3 and a spleen to blood of 1.7 ± 0.2. Heart SUVmean 5 days pi revealed that 10 μg 89Zr-muMSLN HLE cleared faster from the blood (0.5 ± 0.1) than the 50 μg (0.8 ± 0.1, P < 0.01) and the 200 μg dose group (0.8 ± 0.1, P < 0.01). Tumor SUVmean was higher in 50 µg (1.5 ± 0.2) than the 10 µg dose group (1.2 ± 0.1, P < 0.01), but similar to the 200 μg dose group (1.3 ± 0.1, P = 0.28). Spleen uptake 5 days pi was dose-dependent (SUVmean: 10 µg = 1.6 ± 0.2; 50 µg = 1.3 ± 0.1; 200 µg = 0.8 ± 0.1, P < 0.01). Spleen and tumor SUVmean 5 days pi of 50 µg 89Zr-muMSLN HLE BiTE® were higher than 50 µg 89Zr-control HLE BiTE® (spleen = 0.5 ± 0.1, P < 0.01; tumor = 0.8 ± 0.1, P < 0.01), while blood SUVmean of 50 µg 89Zr-control HLE BiTE® was similar (0.6 ± 0.1, P = 0.12).

CONCLUSION: PET imaging with a 89Zr-labeled muMSLN HLE BiTE® in a tumor-bearing syngeneic mouse model revealed a long blood half-life, specific uptake in tumor and spleen, and dose-dependent pharmacokinetics. Taken together, the HLE BiTE® molecule demonstrates an extended pharmacokinetic profile over previously evaluated small, canonical, BiTE® molecules.

Citation Format: Frans V. Suurs, Grit Lorenczewski, Julie M. Bailis, Sabine Stienen, Matthias Friedrich, Elisabeth G.E. de Vries, Derk Jan A. de Groot, Marjolijn N. Lub-de Hooge. PET imaging shows dose-dependent pharmacokinetics of a 89Zr-labeled mesothelin/CD3 half-life extended bispecific T-cell engager molecule in a syngeneic mouse model [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 2769.

The Interleukin 22 Pathway Interacts with Mutant KRAS to Promote Poor Prognosis in Colon Cancer

PURPOSE

The cytokine IL22 promotes tumor progression in murine models of colorectal cancer. However, the clinical significance of IL22 in human colorectal cancer remains unclear. We sought to determine whether the IL22 pathway is associated with prognosis in human colorectal cancer, and to identify mechanisms by which IL22 can influence disease progression.

EXPERIMENTAL DESIGN

Transcriptomic data from stage II/III colon cancers in independent discovery (GSE39582 population-based cohort, N = 566) and verification (PETACC3 clinical trial, N = 752) datasets were used to investigate the association between IL22 receptor expression (encoded by the genes IL22RA1 and IL10RB), tumor mutation status, and clinical outcome using Cox proportional hazard models. Functional interactions between IL22 and mutant KRAS were elucidated using human colorectal cancer cell lines and primary tumor organoids.

RESULTS

Transcriptomic analysis revealed a poor-prognosis subset of tumors characterized by high expression of IL22RA1, the alpha subunit of the heterodimeric IL22 receptor, and KRAS mutation [relapse-free survival (RFS): HR = 2.93, P = 0.0006; overall survival (OS): HR = 2.45, P = 0.0023]. KRAS mutations showed a similar interaction with IL10RB and conferred the worst prognosis in tumors with high expression of both IL22RA1 and IL10RB (RFS: HR = 3.81, P = 0.0036; OS: HR = 3.90, P = 0.0050). Analysis of human colorectal cancer cell lines and primary tumor organoids, including an isogenic cell line pair that differed only in KRAS mutation status, showed that IL22 and mutant KRAS cooperatively enhance cancer cell proliferation, in part through augmentation of the Myc pathway.

CONCLUSIONS

Interactions between KRAS and IL22 signaling may underlie a previously unrecognized subset of clinically aggressive colorectal cancer that could benefit from therapeutic modulation of the IL22 pathway.

Development of a uniform, very aggressive disease phenotype in all homozygous carriers of the NOD2 mutation p.Leu1007fsX1008 with Crohn's disease and active smoking status resulting in ileal stenosis requiring surgery

BACKGROUND

NOD2 variants are the strongest genetic predictors for susceptibility to Crohn's disease (CD). However, the clinical value of NOD2 on an individual patient level remains controversial. We aimed to define the predictive power of the major NOD2 mutations regarding complicated CD in a large single center cohort.

METHODS

1076 CD patients were prospectively genotyped for the three common CD-associated NOD2 mutations rs2066844, rs2066845, and rs2066847, followed by detailed genotype-phenotype analyses.

RESULTS

Overall, 434 CD patients (40.3%) carried at least one of the three main NOD2 mutations. A significantly higher minor allele frequency (15.6%) of the NOD2 frameshift mutation p.Leu1007fsX1008 (rs2066847) was seen in patients with aggressive disease compared to 8.2% in patients with mild disease (p = 2.6 x 10-5). Moreover, a total of 54 CD patients (5.0%) were homozygous for this NOD2 frameshift mutation. 100% of these patients had ileal disease compared to 82% of NOD2 wild-type carriers (p<0.0001). In homozygous carriers of the NOD2 frameshift mutation, 87% presented with ileal stenosis, 68.5% had fistulas, and 72.2% required CD-related surgery despite immunosuppressive therapy in 87% of these patients. All homozygous carriers of the 1007fs mutation who were active smokers had ileal stenosis and required CD-related surgery.

CONCLUSION

Homozygosity for Leu1007fsX1008 is an excellent biomarker for predicting complicated CD on an individual patient level. Active smoking and homozygosity for this mutation is associated with a 100% risk for developing ileal stenosis requiring CD-related surgery. In these patients, smoking cessation and early initiation of immunosuppressive strategies may be beneficial.

A survey on surgeon practice shows lack of consensus on the management of primary shoulder stiffness

Shoulder stiffness is a condition of painful restriction in active and passive glenohumeral range of motion, which can arise spontaneously or as consequence of a known cause. Numerous therapeutic approaches are available; however, no consensus has been reached on the best algorithm for successful treatment. The aim of this study was to investigate local practice patterns regarding management of primary shoulder stiffness. Randomized controlled trials reporting results of shoulder stiffness treatment were collected and analyzed prior to study begin. Controversial elements in the treatment of primary shoulder stiffness were identified and a survey was created and administrated to clinicians participating at an annual national congress dedicated to shoulder pathologies and their treatment. 55 completed questionnaires were collected. Physical therapy was recommended by 98% of the interviewed. The use of oral corticosteroids was considered by 58% and injections of corticosteroids by 60%. Injective therapy with local anaesthetics was considered by 56% of the clinicians and acupuncture by 36%. 38% of the interviewed did never treat shoulder stiffness surgically. Various strategies to manage shoulder stiffness have been proposed and high-level evidence has been published. Numerous controversial points and a substantial lack of consensus emerged both from literature reviews and from this survey. The treatment of shoulder stiffness should be tailored to the patient's clinical situation and the stage of its pathology, aiming primarily at identifying risk factors for recurrence, reducing pain, restoring range of motion and function and shortening the duration of symptoms.

Characterization of a Novel FLT3 BiTE Molecule for the Treatment of Acute Myeloid Leukemia

Despite advances in the treatment of acute myeloid leukemia (AML), novel therapies are needed to induce deeper and more durable clinical response. Bispecific T-cell Engager (BiTE) molecules, which redirect patient T cells to lyse tumor cells, are a clinically validated modality for hematologic malignancies. Due to broad AML expression and limited normal tissue expression, fms-related tyrosine kinase 3 (FLT3) is proposed to be an optimal BiTE molecule target. Expression profiling of FLT3 was performed in primary AML patient samples and normal hematopoietic cells and nonhematopoietic tissues. Two novel FLT3 BiTE molecules, one with a half-life extending (HLE) Fc moiety and one without, were assessed for T-cell-dependent cellular cytotoxicity (TDCC) of FLT3-positive cell lines in vitro, in vivo, and ex vivo FLT3 protein was detected on the surface of most primary AML bulk and leukemic stem cells but only a fraction of normal hematopoietic stem and progenitor cells. FLT3 protein detected in nonhematopoietic cells was cytoplasmic. FLT3 BiTE molecules induced TDCC of FLT3-positive cells in vitro, reduced tumor growth and increased survival in AML mouse models in vivo Both molecules exhibited reproducible pharmacokinetic and pharmacodynamic profiles in cynomolgus monkeys in vivo, including elimination of FLT3-positive cells in blood and bone marrow. In ex vivo cultures of primary AML samples, patient T cells induced TDCC of FLT3-positive target cells. Combination with PD-1 blockade increased BiTE activity. These data support the clinical development of an FLT3 targeting BiTE molecule for the treatment of AML.

The Biodistribution of a CD3 and EpCAM Bispecific T-Cell Engager Is Driven by the CD3 Arm

Bispecific T-cell engager (BiTE) molecules are designed to engage and activate cytotoxic T cells to kill tumor cells. Little is known about their biodistribution in immunocompetent settings. Methods: To explore their pharmacokinetics and the role of the immune cells, BiTE molecules were radiolabeled with the PET isotope ⁸⁹Zr and studied in immunocompetent and immunodeficient mouse models. Results: PET images and ex vivo biodistribution in immunocompetent mice with [⁸⁹Zr]Zr-DFO-N-suc-muS110, targeting mouse CD3 (dissociation constant [K_D], 2.9 nM) and mouse epithelial cell adhesion molecule (EpCAM; K_D, 21 nM), and with [⁸⁹Zr]Zr-DFO-N-suc-hyS110, targeting only mouse CD3 (K_D, 2.9 nM), showed uptake in the tumor, spleen, and other lymphoid organs, whereas the human-specific control BiTE [⁸⁹Zr]Zr-DFO-N-suc-AMG 110 showed similar tumor uptake but lacked spleen uptake. [⁸⁹Zr]Zr-DFO-N-suc-muS110 spleen uptake was lower in immunodeficient than in immunocompetent mice. After repeated administration of nonradiolabeled muS110 to immunocompetent mice, ⁸⁹Zr-muS110 uptake in the spleen and other lymphoid tissues decreased and was comparable to uptake in immunodeficient mice, indicating saturation of CD3 binding sites. Autoradiography and immunohistochemistry demonstrated colocalization of [⁸⁹Zr]Zr-DFO-N-suc-muS110 and [⁸⁹Zr]Zr-DFO-N-suc-hyS110 with CD3-positive T cells in the tumor and spleen but not with EpCAM expression. Also, uptake in the duodenum correlated with a high incidence of T cells. Conclusion: [⁸⁹Zr]Zr-DFO-N-suc-muS110 biodistribution is dependent mainly on the T-cell-targeting arm, with a limited contribution from its second arm, targeting EpCAM. These findings highlight the need for extensive biodistribution studies of novel bispecific constructs, as the results might have implications for their respective drug development and clinical translation.

P2718Interim study: analysis of myocardial deformation using fSENC-CMR on patients with chest pain

Background

In acute situations such as non-ST-elevation infarction (NSTEMI) or relevant coronary artery disease (CAD) CMR does not yet play a key role due to its lengthy protocols. fSENC is a new CMR technique which may detect subclinical signs of myocardial damage by measuring myocardial strain (change in length/ unit length). A whole-heart coverage is generated in 6 heart-beats and the information obtained is converted into a colour-coded map. fSENC does not require major post-processing, long breath-holds and the administration of contrast agents/medication.

Purpose

In this observational study fSENC is assessed in patients with chest pain and its capability to differentiate between an ischemic cause (NSTEMI, significant CAD), an underlying non-ischemic cardiac disease and non-cardiac chest pain. Additionally, we aim to identify the affected coronary arteries in the ischemic cohort. With fSENC it could be possible to successfully diagnose patients with suspected AMI in <1h after admission and also gain diagnostic information regarding the underlying pathology.

Methods

Patients with chest pain and an initial hscTnT level between 5pg/ml and 52 pg/ml are recruited. These patients then undergo an fSENC-CMR before 2nd hscTnT measurement. Additionally, a stress-induced fSENC-image is acquired (1-minute hyperventilation, followed by a single breath-hold). This breathing manoeuvre leads to an increase in oxygenation through vasodilation, therefore identifying ischemic areas. The fSENC analysis is later compared to the patient's final diagnosis and therapy.

Results

So far 50 patients have been analysed by fSENC in this observational study (26 female, aged 57±18). fSENC correctly identified 7 patients suffering from NSTEMI or significant CAD and their affected coronary arteries. 42 other patients were safely ruled-out by fSENC which was consistent with the serial hscTnT results. In 11 patients fSENC was able to detect generalized impaired myocardial deformation, implying an underlying cardiac disease (hypertrophic cardiomyopathy, myocarditis). fSENC currently exhibits a sensitivity of 100% and specificity of 97,7% for correct rule-in/-out of an ischemic cause.

Conclusions

At this stage fSENC allows correct identification of patients suffering from myocardial infarction and their affected coronary arteries. Additionally, fSENC can safely rule-out patients with chest pain but no underlying ischemic cause. This novel technique is a rapid additional diagnostic tool which assesses myocardial function non-invasively without radiation exposure.

TCR and Inflammatory Signals Tune Human MAIT Cells to Exert Specific Tissue Repair and Effector Functions

MAIT cells are an unconventional T cell population that can be activated through both TCR-dependent and TCR-independent mechanisms. Here, we examined the impact of combinations of TCR-dependent and TCR-independent signals in human CD8+ MAIT cells. TCR-independent activation of these MAIT cells from blood and gut was maximized by extending the panel of cytokines to include TNF-superfamily member TL1A. RNA-seq experiments revealed that TCR-dependent and TCR-independent signals drive MAIT cells to exert overlapping and specific effector functions, affecting both host defense and tissue homeostasis. Although TCR triggering alone is insufficient to drive sustained activation, TCR-triggered MAIT cells showed specific enrichment of tissue-repair functions at the gene and protein levels and in in vitro assays. Altogether, these data indicate the blend of TCR-dependent and TCR-independent signaling to CD8+ MAIT cells may play a role in controlling the balance between healthy and pathological processes of tissue inflammation and repair.

Abstract 1134: PET-imaging of 89Zr-labeled bispecific T-cell engagers in syngeneic tumor bearing mice

BACKGROUND Bispecific T-cell engagers (BiTE®) harness the immune system against cancer. BiTE® antibody constructs are small proteins of ~53 kDa existing of two connected single-chain variable fragments. MuS110, a BiTE® with affinity for murine CD3 (KD= 2.9 nM) and murine EpCAM (KD= 21 nM), was radiolabeled with positron emission tomography (PET) isotope zirconium-89 (89Zr) to study its pharmacokinetics and involvement of the immune system in an immunocompetent mouse model bearing a syngeneic tumor.

METHODS MuS110 and two control BiTE® antibody constructs (hyS110 and AMG110) were radiolabeled with 89Zr. HyS110 has affinity for murine CD3 and human EpCAM, AMG110 for human CD3 and human EpCAM. The human and murine variants of EpCAM and CD3 are not cross-reactive. Either immunocompetent BALB/c or immunodeficient nude BALB/c mice were all orthotopically engrafted in the lower mammary fat pad with EpCAM-positive murine breast cancer cell line 4T1. PET-imaging was performed at 0.5, 3, 6, 24, 48 and 72 h after intravenous (iv) administration of 10 µg 89Zr-muS110. Distribution of 10 µg 89Zr-muS110, 89Zr-hyS110 and 89Zr-AMG110 was assessed 24 h after administration in BALB/c and nude BALB/c mice with PET-imaging and ex-vivo biodistribution. In addition, a group of BALB/c mice received 10 µg muS110 iv daily for 5 days followed by 10 µg 89Zr-muS110 or 10 µg 89Zr-AMG110 and PET-imaging 24 h after tracer administration. Values are expressed as median (interquartile range).

RESULTS PET-imaging revealed fast renal clearance of 89Zr-muS110 in the BALB/c mice resulting in a blood half-life of 0.93 h (one-phase decay). Tumor- and spleen-to-blood ratios increased to 3.7 (3.0 to 4.5) and 9.3 (7.5 to 11.1) after 72 h. Ex-vivo biodistribution 24 h after tracer administration showed 89Zr-muS110 and 89Zr-hyS110 accumulation in the spleen with 8.2 % injected dose per gram (ID/g) and 8.7 %ID/g, in comparison to 89Zr-AMG110 (2.3 %ID/g; vs 89Zr-muS110 P&lt;0.05, vs 89Zr-hyS110 P&lt;0.05). In mesenteric lymph nodes (mesLNs), 89Zr-muS110 and 89Zr-hyS110 resulted in a higher uptake (3.5 and 6.4 %ID/g) than 89Zr-AMG110 (2.0 %ID/g; vs 89Zr-muS110 P&lt;0.05, vs 89Zr-hyS110 P&lt;0.05). Tumor uptake did not differ for 89Zr-muS110 and 89Zr-AMG110 (2.6 vs 2.2 %ID/g, P&gt;0.05). In nude BALB/c mice spleen and mesLN uptake of 89Zr-muS110 was lower than in BALB/c mice (spleen: 3.4 vs 8.2 %ID/g, P&lt;0.05; mesLNs: 1.7 vs 3.5, P&lt;0.05). In addition, in nude BALB/c mice, tumor uptake was the same for 89Zr-muS110 and 89Zr-AMG110 (1.5 vs 1.7 %ID/g, P&gt;0.05). 89Zr-muS110 uptake was lower in spleen and mesLNs following 5 days of 10 µg muS110 iv compared to control mice

(spleen: 4.2 vs 8.2 %ID/g, P&lt;0.01; mesLNs: 1.9 vs 3.5, P&lt;0.01), likely representing target saturation.

CONCLUSION Distribution of BiTE® 89Zr-muS110 is predominantly mediated by the affinity for CD3, resulting in uptake in lymphoid tissues.

Citation Format: Frans V. Suurs, Derk J. de Groot, Urszula M. Domanska, Grit Lorenczewski, Sabine Stienen, Matthias Friedrich, Elisabeth G. de Vries, Marjolijn N. Lub-de Hooge. PET-imaging of 89Zr-labeled bispecific T-cell engagers in syngeneic tumor bearing mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1134.

[Endoprosthetic replacement of the proximal humerus in revision shoulder arthroplasty]

OBJECTIVE

Reconstruction of proximal humeral bone defects in the setting of shoulder revision arthroplasty by implantation of a modular humeral component.

INDICATIONS

Severe segmental humeral bone defects in revision total shoulder arthroplasty, after tumor resection, trauma, pathological fractures, post-infectious or after failed osteosynthesis.

CONTRAINDICATIONS

Acute or chronic local infections, large diaphyseal bone defects preventing adequate anchorage of the prosthesis, very short life expectancy (<3 months).

SURGICAL TECHNIQUE

Removal of the implant using an extended deltopectoral approach. Periarticular arthrolysis with preservation of neurovascular structures. Resection of the meta-diaphyseal bone and reconstruction of the humeral length with the help of different extension sleeves and a modular humeral component. Soft tissue management is crucial, especially with reverse shoulder arthroplasty.

POSTOPERATIVE MANAGEMENT

Three weeks postoperatively immobilization in a shoulder sling, active assisted movement therapy by gradual pain-adapted increase of movement, muscle coordination, and strength.

RESULTS

The results of 11 consecutive patients treated with a modular humeral component due to a failed shoulder arthroplasty between 2008 and 2016 were evaluated retrospectively. Mean length of reconstruction was 100 mm. Due to recurrent dislocations one patient required revision and conversion to a reverse component. No cases of aseptic loosening or periprosthetic infection were observed.

Model for Hormonal Emergency Contraception (HEC) in cycling and mated guinea pigs - Studies with the Progesterone Receptor Modulators (PRM) Ulipristal Acetate (UPA/CDB2914) and EC317

A guinea pig model for new HEC methods is proposed. Two targets for HEC (Hormonal Emergency Contraception), ovulation and conception (post-mating study), were investigated using adjusted PRM treatments: (a) Ovulation inhibition study: Injections on cycle days 10-17, study of ovarian histology on day 18; (b) post-mating study: Injections on cycle days 1 and 2; rate of pregnant females was recorded at autopsy on day 18. P plasma levels permitted assessment of effects on ovulation in non-conceiving animals.

RESULTS

(a) All controls had recently ovulated. Statistically significant anti-ovulatory effects (p < 0.05, Fisher's Exact Test) were seen at 10 mg UPA (ulipristal acetate, CDB2914) and ≥0.3 mg EC317; 100% inhibition was found for EC317 at 10, 3, and 1 mg/day. No dosage of UPA was 100% effective. (b) In post-mating studies, 16 of 30 controls were pregnant. Both PRMs (progesterone receptor modulator) exerted inhibitory effects on conception, none on imminent ovulation; 1 of 10 animals had living conceptuses after 10 mg UPA, none following 10 and 1 mg EC317/day, respectively. At pairwise comparison with controls, 10 mg was the lowest effective dosage for UPA (p < 0.05), and 1 mg for EC317 (p < 0.01). P plasma levels: Significantly lower P (p < 0.05) in subsequently pregnant vs non-pregnant controls was found on cycle day 3 or 4; this difference disappeared on day 8 or 9. This stage thus appears vulnerable to hormonal constellations and possibly PRM effects. HEC model: Effects on ovulation and conception were seen at the same dose levels of both PRM. Superior and more consistent effects of EC317 vs UPA (factor ≥10) suggest higher efficacy using EC317 for HEC.