Abstract 735: SAR of amanitin and optimization of linker-amanitin derivatives for solid tumors

Background:

ATACs (Antibody Targeted Amanitin Conjugates) comprise a new class of antibody-drug conjugates using amanitin as toxic payload. Amanitin binds to the eukaryotic RNA pol II and thereby inhibits the cellular transcription process at very low concentrations. We accomplished the chemical synthesis of amanitin and were able to synthesize amanitin variants in order to optimize the toxin structure for different tumors and antibodies. We will present in vitro and in vivo data of eight different linker-amanitin constructs attached to three different antibodies targeting solid tumors.

Material and methods:

Cell lines: JIMT-1, SKBR-3, BT474 and NCI-N87 (used for anti-Her-2-ATACs); LnCap, 22RV1, MDA-PCa2b and C4.2 (used for anti-PSMA-ATACs); Raji, Raji Luc, Nalm-6 and MEC-2 (used for anti-CD19-ATACs)

Antibodies: Anti-Her-2 (cysteine engineered monoclonal antibody, Heidelberg Pharma); humanized anti-PSMA (Albert Ludwig University Freiburg, medical center; humanization at Lonza Group AG; cysteine engineered monoclonal antibody, Heidelberg Pharma); chimeric anti-CD19 (DKFZ Heidelberg, Germany; cysteine engineered monoclonal antibody, Heidelberg Pharma).

Toxic warhead: Cysteine reactive linker-amanitin constructs were synthesized at Heidelberg Pharma and conjugated site-specifically to the antibodies.

Cell proliferation assay: Quantitative determination of cell viability was performed by CellTiter Glo 2.0 assay (Promega).

Animal models: Subcutaneous Mouse xenograft tumor models (Her-2-, PSMA- and CD19-positive cell lines) were performed in single-dose experiments. Tolerability was assessed in mice and will be assessed in non-human primates (NHP).

Results:

Eight different amanitin-linker constructs were synthesized. They differed in the attachment site of the linker at the amanitin as well as in the toxin core structure. All ATACs showed in vitro cytotoxicity on target positive cell lines in the picomolar range.

In mouse xenograft models, ATACs with four of the eight linker-amanitin derivatives caused dose-dependent tumor regression and complete remission after a single i.v. dose of 2.0 mg/kg in s.c. xenografts irrespective of the antibody and target used. In contrast the other four linker-amanitin derivatives were only poorly effective in vivo while showing comparable in vitro activities. When comparing subcutaneous and intravenous xenograft models using the same cancer cell line, the different efficacy of the eight linker-amanitin variants was only detected in subcutaneous but not in intravenous xenografts. Mouse tolerability studies of ATACs showed a MTD of at least 10mg/kg for all linker-amanitin variants.

Conclusions:

Different efficacy of linker-amanitin derivatives with regard to mouse xenograft models was detected. An SAR profile of amanitin could be established which enabled the selection of optimized linker-amanitin variants for the use of ATACs in solid tumors.

Citation Format: Michael Kulke, Anikó Pálfi, Christoph Müller, Werner Simon, Susanne Werner-Simon, Christian Lutz, Torsten Hechler, Andreas Pahl. SAR of amanitin and optimization of linker-amanitin derivatives for solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 735.

Percutaneous Medial Ligament Reconstruction for Valgus Knee Instability

Injuries to stabilizing elements on the medial side of the knee are one of the most common knee ailments. Because of the good healing capacity of these structures, acute injuries are typically treated conservatively. However, valgus laxity near full extension can persist in some patients. This laxity may be the source of instability due to medial joint space opening, which then requires surgical treatment. Various procedures have been described that aim to reproduce the anatomy of the medial collateral ligament (MCL) and the posterior oblique ligament (POL), which work together to stabilize the medial aspect of the knee. However, these are complex open surgical procedures, technically demanding to achieve the favorable isometry, which prevent joint contracture or recurrence of laxity. The purpose of this study was to describe a short construct that minimizes the risk of secondary loss of tension and complies with the principle of favorable anisometry. The graft is positioned in the joint opening axis, between the deep bundle of the MCL and the POL.

Exocrine pancreas glutamate secretion help to sustain enterocyte nutritional needs under protein restriction

Glutamine (Gln) is the most concentrated amino acid in blood and considered conditionally essential. Its requirement is increased during physiological stress, such as malnutrition or illness, despite its production by muscle and other organs. In the malnourished state, Gln has been suggested to have a trophic effect on the exocrine pancreas and small intestine. However, the Gln transport capacity, the functional relationship of these two organs, and the potential role of the Gln-glutamate (Glu) cycle are unknown. We observed that pancreatic acinar cells express lower levels of Glu than Gln transporters. Consistent with this expression pattern, the rate of Glu influx into acinar cells was approximately sixfold lower than that of Gln. During protein restriction, acinar cell glutaminase expression was increased and Gln accumulation was maintained. Moreover, Glu secretion by acinar cells into pancreatic juice and thus into the lumen of the small intestine was maintained. In the intestinal lumen, Glu absorption was preserved and Glu dehydrogenase expression was augmented, potentially providing the substrates for increasing energy production via the TCA cycle. Our findings suggest that one mechanism by which Gln exerts a positive effect on exocrine pancreas and small intestine involves the Gln metabolism in acinar cells and the secretion of Glu into the small intestine lumen. The exocrine pancreas acinar cells not only avidly accumulate Gln but metabolize Gln to generate energy and to synthesize Glu for secretion in the pancreatic juice. Secreted Glu is suggested to play an important role during malnourishment in sustaining small intestinal homeostasis. NEW & NOTEWORTHY Glutamine (Gln) has been suggested to have a trophic effect on exocrine pancreas and small intestine in malnourished states, but the mechanism is unknown. In this study, we suggest that this trophic effect derives from an interorgan relationship between exocrine pancreas and small intestine for Gln-glutamate (Glu) utilization involving the uptake and metabolism of Gln in acinar cells and secretion of Glu into the lumen of the small intestine.

Dry adhesives from carbon nanofibers grown in an open ethanol flame

Based on magnetic-field-assisted growth of carbon nanofibers in an open ethanol flame we fabricated arrays of carbon nanofibers with different degrees of orientation. Inspired by the dry adhesive system of geckos we investigated the adhesive properties of such carbon nanofiber arrays with ordered and random orientation. AFM-based force spectroscopy revealed that adhesion force and energy rise linear with preload force. Carbon nanofibers oriented by a magnetic field show a 68% higher adhesion (0.66 N/cm²) than the randomly oriented fibers. Endurance tests revealed that the carbon nanofiber arrays withstand 50.000 attachment/detachment cycles without observable wear.

Myeloid differentiation primary response gene (MyD) 88 signalling is not essential for intestinal fibrosis development

Dysregulation of the immune response to microbiota is associated with inflammatory bowel disease (IBD), which can trigger intestinal fibrosis. MyD88 is a key component of microbiota signalling but its influence on intestinal fibrosis has not been clarified. Small bowel resections from donor-mice were transplanted subcutaneously into the neck of recipients C57BL/6 B6-MyD88tm1 Aki (MyD88^-/-) and C57BL/6-Tg(UBC-green fluorescence protein (GFP))30Scha/J (GFP-Tg). Grafts were explanted up to 21 days after transplantation. Collagen layer thickness was determined using Sirius Red stained slides. In the mouse model of fibrosis collagen deposition and transforming growth factor-beta 1 (TGF-β1) expression was equal in MyD88^+/+ and MyD88^-/-, indicating that MyD88 was not essential for fibrogenesis. Matrix metalloproteinase (Mmp)9 expression was significantly decreased in grafts transplanted into MyD88^-/- recipients compared to MyD88^+/+ recipients (0.2 ± 0.1 vs. 153.0 ± 23.1, respectively, p < 0.05), similarly recruitment of neutrophils was significantly reduced (16.3 ± 4.5 vs. 25.4 ± 3.1, respectively, p < 0.05). Development of intestinal fibrosis appears to be independent of MyD88 signalling indicating a minor role of bacterial wall compounds in the process which is in contrast to published concepts and theories. Development of fibrosis appears to be uncoupled from acute inflammation.

Combined intra- and extra-articular grafting for revision ACL reconstruction: A multicentre study by the French Arthroscopy Society (SFA)

BACKGROUND

A careful analysis of the reasons for ACL reconstruction failure is essential to selection of the optimal surgical revision technique designed to ensure good rotational stability and to minimise the risk of re-rupture.

OBJECTIVE

To evaluate anterolateral ligament (ALL) stabilisation during revision ACL reconstruction.

HYPOTHESIS

ALL stabilisation during revision ACL reconstruction provides good rotational stability without increasing the risk of complications.

MATERIAL AND METHODS

This multicentre study included 349 patients, 151 retrospectively and 198 prospectively. There were 283 males and 66 females. Inclusion criteria were an indication for revision ACL reconstruction surgery with combined intra-articular reconstruction and ALL stabilisation after failed autograft ACL reconstruction, and intact PCL. Exclusion criteria were primary ACL reconstruction and concomitant peripheral medial and/or lateral lesions. Each patient underwent a clinical and radiographic evaluation before and after revision surgery. Before revision surgery, the mean IKDC score was 56.5±15.5 and 96% of patients were IKDC C or D.

RESULTS

Rates were 5.0% for early and 10.5% for late postoperative complications. Lachmann's test had a hard stop at last follow-up in 97% of patients. The pivot-shift test was positive in 1% of patients. The mean subjective IKDC score was 84.5±13.0 and 86.5% of patients were IKDC A or B. The proportions of patients with radiographic knee osteoarthritis at last follow-up was unchanged for the lateral tibio-femoral and patello-femoral compartments but increased by 9.7% to 21.2% for the medial tibio-femoral compartment. The re-rupture rate was 1.2% and the further surgical revision rate was 5.4%.

CONCLUSION

Anterior laxity at last follow-up was consistent with previous studies of revision ACL reconstruction. However, rotational stability and the re-rupture risk were improved. ALL stabilisation is among the techniques that deserve consideration as part of the therapeutic options for revision ACL reconstruction.

LEVEL OF EVIDENCE

IV, retrospective and prospective cohort study.

Midterm results of combined intra- and extra-articular ACL reconstruction compared to historical ACL reconstruction data. Multicenter study of the French Arthroscopy Society

INTRODUCTION

During anterior cruciate ligament (ACL) reconstruction procedures, anterolateral reconstruction (ALR) can also be performed to improve the knee's rotational stability. However, the effectiveness of this supplemental technique and its impact on the risk of retears and on the onset of secondary degenerative changesare controversial.

HYPOTHESIS

ALR improves control over the pivot shift, reduces the retear risk and delays the appearance of secondary degenerative lesions.

MATERIAL AND METHODS

Clinical examination, knee laxity measurements and X-ray evaluations were done in 478 patients with more than 3years' follow-up after combined ACL and ALR from 11 participating hospitals. The mean patient age at the time of surgery was 28years. Eighty-eight percent of the patients participated in pivot sports and 45% were competitive athletes. The findings of this study were compared to historical isolated ACL reconstruction data.

RESULTS

The average follow-up was 6.8years. No detectable pivot shift was found in 83% of patients, while 12.8% of patient had a smooth glide. The side-to-side difference in anteroposterior knee laxity with maximum manual force was less than 3mm in 66% of patients and less than 5mm in 95%. The retear rate was 5.4%, with half of these patients undergoing revision ACL surgery. Secondary meniscus damage requiring surgery occurred in 6.3% of patients; the radiological osteoarthritis rate was 17.5%.

DISCUSSION

When compared to historical ACL reconstruction data, combined intra- and extra-articular reconstruction does not increase the complication rate. At a mean follow-up of 6.8years, it provides better control over the pivot shift along with a low retear rate and low occurrence of secondary meniscus injuries.

LEVEL OF EVIDENCE

IV, multicenter study.

High-frequency burst vagal nerve simulation therapy in a natural primate model of genetic generalized epilepsy

PURPOSE

Since the approval of Vagal Nerve Stimulation (VNS) Therapy for medically refractory focal epilepsies in 1997, it has been also reported to be effective for a wide range of generalized seizures types and epilepsy syndromes. Instead of conventional VNS Therapy delivered at 20-30Hz signal frequencies, this study evaluates efficacy and tolerability of high-frequency burst VNS in a natural animal model for genetic generalized epilepsy (GGE), the epileptic baboon.

METHODS

Two female baboons (B1 P.h. Hamadryas and B2 P.h. Anubis x Cynocephalus) were selected because of frequently witnessed generalized tonic-clonic seizures (GTCS) for VNS implantation. High-frequency burst VNS Therapy was initiated after a 4-5 week baseline; different VNS settings (0.25, 2 or 2.5mA, 300Hz, 4 vs 7 pulses, 0.5-2.5s interburst interval, and intermittent stimulation for 1-2 vs for 24h per day) were tested over the subsequent 19 weeks, which included a 4-6 week wash-out period. GTCS frequencies were quantified for each setting, while seizure duration and postictal recovery times were compared to baseline. Scalp EEG studies were performed at almost every setting, including intermittent light stimulation (ILS) to evaluate photosensitivity. Pre-ILS ictal and interictal discharge rates, as well as ILS responses were compared between trials. The Novel Object test was used to assess potential treatment effects on behavior.

RESULTS

High-frequency burst VNS Therapy reduced GTCS frequencies at all treatment settings in both baboons, except when output currents were reduced (0.25mA) or intermittent stimulation was restricted (to 1-2h/day). Seizure duration and postictal recovery times were unchanged. Scalp EEG studies did not demonstrate treatment-related decrease of ictal or interictal epileptic discharges or photosensitivity, but continuous treatment for 120-180s during ILS appeared to reduce photoparoxysmal responses. High-frequency burst VNS Therapy was well-tolerated by both baboons, without cardiac or behavioral changes. Repetitive muscle contractions involving the neck and left shoulder girdle were observed intermittently, most commonly at 0.5 interburst intervals, but these were transient, resolving with a few cycles of stimulation and not noted in wakefulness.

CONCLUSIONS

This preclinical pilot study demonstrates efficacy and tolerability of high-frequency burst VNS Therapy in the baboon model of GGE. The muscle contractions may be due to aberrant propagation of the stimulus along the vagal nerve or to the ansa cervicalis, but can be reduced by minimal adjustment of current output or stimulus duration.

Abstract 77: Preclinical evaluation of HDP-101, an anti-BCMA antibody-drug conjugate

Background:

ATACs (antibody-targeted Amanitin conjugates) comprise a new class of antibody-drug conjugates using amanitin as toxic payload. Amanitin binds to the eukaryotic RNA pol II and thereby inhibits the cellular transcription process at very low concentrations. In the current study, in vitro and in vivo data of new ATACs targeting BCMA (B Cell Maturation Antigen, also known as CD269) are presented. BCMA is selectively expressed on malignant plasma cells like in multiple myeloma (MM) and hence considered an ideal target for Amanitin based ADCs.

Material and methods:

MM cell lines: NCI-H929, MM.1S Luc (stable luciferase transfected) and CCRF-CEM (BCMA negative).

Antibody: anti-BCMA Thiomab (Max Delbrück Centrum, Berlin; derivatization and production at Heidelberg Pharma).

Synthesis of HDP-101: Maleimide amanitin compounds were conjugated to substituted cysteine residues of the anti-BCMA Thiomab.

Cell proliferation assay: Quantitative determination of cytotoxicity was performed by CellTiter Glo 2.0 assay (Promega) or WST.1 assay (Roche).

Animal models: Subcutaneous and metastatic mouse xenograft tumor models with MM cell lines NCI-H929 and MM.1S Luc were performed in single-dose and multiple-dosing experiments. Tolerability was assessed in mice and nonhuman primates (NHP).

Results:

HDP-101 showed in vitro cytotoxicity on BCMA+ cell lines in picomolar range, whereas no cytotoxic activity on BCMA- cells was observed.

In mouse xenograft models, HDP-101 caused dose-dependent tumor regression and complete remission after a single i.v. dose of 2.0 mg/kg and 4.0 mg/kg in s.c. xenografts and after single i.v. doses from 0.1 mg/kg to 2.0 mg/kg in disseminating xenografts.

Safety profiling in Cynomolgus monkeys revealed a good tolerability and therapeutic index after sequentially applied doses of 0.3, 1.0, and multiple dose application of 4 x 3.0 mg/kg. Hematology and clinical chemistry parameters were unaffected except liver enzymes and LDH: A mild to moderate and transient increase was observed. The half-life of the ADC in serum was 7-9 days; the free toxin was detectable at levels close to the lower limit of quantification only (LLOQ = 1.2nM).

Conclusions:

Targeted cytotoxic drug delivery to BCMA positive MM cell lines was achieved by using HDP-101, an anti-BCMA-ATAC. The mode of action of the payload Amanitin led to an efficient anti-tumor potential in vitro and in vivo with good tolerability in NHP studies. Using ADCs in the therapy of multiple myeloma is a promising approach, especially by using a cytotoxic agent whose mode of action differs from other commonly used toxins, like ATACs. First-in-human trial is expected to start in 2018.

Citation Format: Torsten Hechler, Aniko Palfi, Christoph Müller, Christian Lutz, Andreas Pahl, Michael Kulke. Preclinical evaluation of HDP-101, an anti-BCMA antibody-drug conjugate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 77. doi:10.1158/1538-7445.AM2017-77

Abstract B77: CYP3A5 mediates basal and acquired therapy resistance in different subtypes of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive disease with poor prognosis. Treatment with gemcitabine, the FOLFIRINOX scheme or nab-paclitaxel offer only a modest increase in overall survival. For a number of other carcinomas, tumor subtypes have been uncovered that allow the use of targeted therapies. Although subtypes of PDAC were described, this malignancy is clinically still treated as a single disease. We established patient-derived models representing the full spectrum of previously identified quasi-mesenchymal (QM-PDA), classical and exocrine-like PDAC subtypes, and identified two markers—HNF1A and KRT81—that enable stratification of tumors into different subtypes by immunohistochemistry. Patients bearing tumors of these subtypes show significant differences in overall survival and their tumors differ in drug sensitivity, with the exocrine-like subtype being resistant to tyrosine kinase inhibitors and paclitaxel. The xenobiotic enzyme, cytochrome P450 3A5 (CYP3A5), metabolizes these compounds in tumors of the exocrine-like subtype, and pharmacological or short hairpin RNA (shRNA)-mediated CYP3A5 inhibition sensitizes tumor cells to these drugs. Additionally, retrospective analysis of a large patient cohort confirmed that CYP3A5 is predominantly found in those patient tumors classified as exocrine-like. Whereas the hepatocyte nuclear factor 4, alpha (HNF4A) controls basal expression of CYP3A5, drug-induced CYP3A5 upregulation is mediated by the nuclear receptor NR1I2. Interfering with these regulatory mechanisms may provide an alternative approach to suppress the CYP3A5 pathway. CYP3A5 also contributes to acquired drug resistance in QM-PDA and classical PDAC, and is highly expressed in several additional malignancies. These findings designate CYP3A5 as predictor of therapy response and as a tumor cell-autonomous detoxification mechanism that must be overcome to prevent drug resistance.

Citation Format: Elisa M. Noll, Christian Eisen, Albrecht Stenzinger, Elisa Espinet, Alexander Muckenhuber, Corinna Klein, Vanessa Vogel, Bernd Klaus, Wiebke Nadler, Christoph Rösli, Christian Lutz, Michael Kulke, Jan Engelhardt, Franziska Zickgraf, Octavio Espinosa, Matthias Schlesner, Xiaoqi Jiang, Annette Kopp-Schneider, Peter Neuhaus, Marcus Bahra, Bruno V. Sinn, Roland Eils, Nathalia A. Giese, Thilo Hackert, Oliver Strobel, Jens Werner, Markus W. Büchler, Wilko Weichert, Andreas Trumpp, Martin R. Sprick.{Authors}. CYP3A5 mediates basal and acquired therapy resistance in different subtypes of pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B77.

Anesthesia and analgesia methods for outpatient anterior cruciate ligament reconstruction

INTRODUCTION

More and more anterior cruciate ligament (ACL) reconstructions are being performed as outpatient surgery in France, because of economic considerations. Postoperative pain is the most common reason for delayed discharge that could require hospitalization, and the main reason for unanticipated hospital admission. The purpose of this study was to define the best anesthesia and analgesia methods for ACL reconstruction.

MATERIALS AND METHODS

This was a prospective, multicenter, comparative study performed between January 2014 and April 2015. Inclusion criteria were ACL reconstruction in patients above 15 years of age performed as an outpatient surgical procedure. The anesthesia techniques analyzed were general anesthesia, spinal anesthesia and quadruple nerve blockade. The analgesic methods studied were single-shot nerve blocks, continuous nerve blocks, peri-articular and intra-articular local infiltration analgesia (LIA), non-steroidal anti-inflammatory agents (NSAIDs) and intravenous corticosteroids. The main outcome criterion was pain on a visual analog scale (VAS). The secondary outcome criteria were delayed discharge of a patient who had undergone outpatient surgery, consumption of opioids and complications for the various anesthesia techniques and analgesia methods.

RESULTS

In all, 680 patients were included in this study, which was 63% of the ACL reconstruction procedures performed during this period. The study population was 69% male and 31% female, with an average age of 30 years. Twenty-three patients (3.4%) could not be discharged on the day of surgery. No correlation was found with the anesthesia technique used. NSAID treatment was protective relative to delayed discharge (P=0.009), while opioid consumption was a risk factor (P<0.01). There were no differences in the pain levels related to the type of anesthesia. Peri-articular LIA of the hamstring tendon harvest site was effective. Intra-articular LIA did not provide better analgesia. Continuous nerve block had complication rates above 13%.

DISCUSSION

All types of anesthesia were compatible with outpatient ACL reconstruction. No gold standard analgesia method can be defined based on this study's findings. However, we recommend multimodal analgesia associating peri-articular LIA or one-shot sensory saphenous nerve block, NSAIDs and corticosteroid treatment, and cryotherapy.

LEVEL OF EVIDENCE

II, prospective comparative non-randomized study.

Isometric Characteristics of the Anterolateral Ligament of the Knee: A Cadaveric Navigation Study

PURPOSE

To measure the variations in length during flexion and internal tibial rotation of the 3 different femoral insertions of the anterolateral ligament (ALL) while maintaining a fixed tibia insertion.

METHODS

Twelve fresh-frozen cadaver knees were analyzed using a navigation system. Maximal distance variations of the 3 different anatomic femoral insertions of the ALL were measured during knee flexion and internal tibial rotation at 20° (IR20°) and 90° (IR90°). The 3 different femoral attachments were, as published, at the center of the lateral epicondyle, distal and anterior from this position, and proximal and posterior. Each of these 3 femoral insertions was coupled to the same tibial insertion at the tibial margin, halfway between the tip of the fibular head and the prominence of the Gerdy tubercle.

RESULTS

During IR20°, variation in the distance between paired points is not different between the proximal-posterior, epicondyle, and distal-anterior femoral insertions. These variations were statistically different during IR90° for the 3 different femoral locations. In increasing degrees of flexion, there was a length decrease between paired points observed with the proximal-posterior position. A length increase was observed for both the epicondyle location and the distal-anterior location.

CONCLUSIONS

The ALL did not reveal an isometric behavior at any of the femoral insertion locations but had different length change patterns during knee flexion and internal tibial rotation at 90°. The proximal and posterior to epicondyle femoral position is the only position with a favorable isometry, as shown by being tight in extension and in internal rotation at 20° and then relaxed when the knee goes to flexion at 120° and during internal rotation at 90°.

CLINICAL RELEVANCE

Clinical relevance is significant with respect to optimizing the femoral position of an ALL reconstruction.

Ag2S atomic switch-based 'tug of war' for decision making

For a computing process such as making a decision, a software controlled chip of several transistors is necessary. Inspired by how a single cell amoeba decides its movements, the theoretical 'tug of war' computing model was proposed but not yet implemented in an analogue device suitable for integrated circuits. Based on this model, we now developed a new electronic element for decision making processes, which will have no need for prior programming. The devices are based on the growth and shrinkage of Ag filaments in α-Ag2+δS gap-type atomic switches. Here we present the adapted device design and the new materials. We demonstrate the basic 'tug of war' operation by IV-measurements and Scanning Electron Microscopy (SEM) observation. These devices could be the base for a CMOS-free new computer architecture.

Abstract LB-120: CYP3A5 mediates basal and acquired therapy resistance in different subtypes of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive disease with poor prognosis. Treatment with gemcitabine, the FOLFIRINOX scheme or nab-paclitaxel offer only a modest increase in overall survival. For a number of other carcinomas, tumor subtypes have been uncovered that allow the use of targeted therapies. Although subtypes of PDAC were described, this malignancy is clinically still treated as a single disease. We established patient-derived models representing the full spectrum of previously identified quasi-mesenchymal (QM-PDA), classical and exocrine-like PDAC subtypes, and identified two markers—HNF1A and KRT81—that enable stratification of tumors into different subtypes by immunohistochemistry. Patients bearing tumors of these subtypes show significant differences in overall survival and their tumors differ in drug sensitivity, with the exocrine-like subtype being resistant to tyrosine kinase inhibitors and paclitaxel. The xenobiotic enzyme, cytochrome P450 3A5 (CYP3A5), metabolizes these compounds in tumor cells of the exocrine-like subtype, and pharmacological or short hairpin RNA (shRNA)-mediated CYP3A5 inhibition sensitizes tumor cells to these drugs. Additionally, retrospective analysis of a large patient cohort confirmed that CYP3A5 is predominantly found in those patient tumors classified as exocrine-like (Noll, Eisen et al., Nature Medicine (2016) accepted). Whereas the hepatocyte nuclear factor 4, alpha (HNF4A) controls basal expression of CYP3A5, drug-induced CYP3A5 upregulation is mediated by the nuclear receptor NR1I2. Interfering with these regulatory mechanisms may provide an alternative approach to suppress the CYP3A5 mediated resistance pathway. CYP3A5 also contributes to acquired drug resistance in QM-PDA and classical PDAC in vitro and in vivo. Finally, CYP3A5 is highly expressed in several additional malignancies including hepatocellular and cervical carcinomas raising the possibility that the CYP3A5 resistance mechanism is operational in a variety of human cancers. These findings designate CYP3A5 as predictor of therapy response and as a tumor cell-autonomous detoxification mechanism that must be overcome to prevent drug resistance.

Citation Format: Elisa M. Noll, Christian Eisen, Albrecht Stenzinger, Elisa Espinet, Alexander Muckenhuber, Corinna Klein, Vanessa Vogel, Bernd Klaus, Wiebke Nadler, Christoph Rösli, Christian Lutz, Michael Kulke, Jan Engelhardt, Franziska Zickgraf, Octavio Espinosa, Matthias Schlesner, Xiaoqi Jiang, Annette Kopp-Schneider, Peter Neuhaus, Marcus Bahra, Bruno Sinn, Roland Eils, Nathalia Giese, Thilo Hackert, Oliver Strobel, Jens Werner, Markus W. Büchler, Wilko Weichert, Andreas Trumpp, Martin R. Sprick. CYP3A5 mediates basal and acquired therapy resistance in different subtypes of pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-120.

The Involvement of the Anterolateral Ligament in Rotational Control of the Knee

BACKGROUND

Rotational control of the knee is crucial for knee stability. The anterolateral ligament (ALL) has been identified as a potentially important structure involved in rotational control of the knee.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine, utilizing a navigation system, the involvement of the anterior cruciate ligament (ACL), the iliotibial band (ITB), and the ALL in tibial internal rotational control of the knee. The hypothesis was that the ALL would be involved in rotational control of the knee at varying degrees of knee flexion.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve fresh-frozen cadaveric knees were tested in internal rotation at 20° and 90° of flexion and then subsequently tested using a simulated pivot-shift test consisting of coupled axial rotation at 30° of flexion. Serial sectioning of the ACL, ALL, and ITB was performed. On the contralateral knee, sectioning was performed in the reverse order. Measurements were collected using a surgical navigation system before and after each sectioning.

RESULTS

After ACL sectioning, an incision of the ALL induced a significant increase in internal rotation (+19.2% [P = .0002] at 20°; +21.8% [P = .0029] at 90°) and in coupled axial rotation (+43.0%; P = .0035) compared with the intact knee as well as a significant increase in internal rotation at 90° (+13.4%; P = .009) and in coupled axial rotation (+30.8%; P = .0124) compared with the ACL-deficient knee. After ITB sectioning, an additional ALL section caused a significant increase in internal rotation (+39.0% [P = .002] at 20°; +63.0% [P = .0147] at 90°) and in coupled axial rotation (+59.7%; P = .0003) compared with the intact knee as well as a significant increase in internal rotation at 90° (+14.8%; P = .0067) in comparison to the ITB-deficient knee.

CONCLUSION

The ALL is involved in rotational control of the knee at varying degrees of knee flexion and during a simulated pivot shift. Concomitant to an ACL or ITB transection, sectioning the ALL further increased rotational laxity.

CLINICAL RELEVANCE

This laboratory study demonstrated that the ALL provides rotational control of the knee in combination with the ACL and/or ITB.

Femoral Origin of the Anterolateral Ligament: An Anatomic Analysis

PURPOSE

To determine the location and variability of the anterolateral ligament (ALL) femoral origin.

METHODS

The ALL was dissected and examined in 52 embalmed specimens, and the femoral origin was isolated. The presence of a bony or soft-tissue attachment, the relation to the lateral collateral ligament, the average diameter of the proximal origin, and the specific location of the origin relative to the lateral femoral epicondyle were recorded.

RESULTS

The ALL was present in all 52 specimens, with a mean diameter of 11.85 mm, and was consistently attached to bone in all specimens. The ALL consistently overlapped the lateral collateral ligament near its attachment, with the location of the origin directly on the lateral epicondyle in 12 specimens (23%), with a shared lateral femoral condyle and with the origin slightly posterior and proximal to the lateral epicondyle in 30 specimens (58%), and with the origin completely posterior and proximal to the lateral epicondyle in 10 specimens (19%).

CONCLUSIONS

The ALL showed a consistent bony origin overlapping the lateral collateral ligament in all specimens, with some variability in the femoral attachment, ranging from directly on the lateral epicondyle to posterior to the lateral epicondyle.

CLINICAL RELEVANCE

The identification and description of the femoral origin of the ALL are crucial in understanding its role in the stability of the knee, as well as determining the appropriate position for the femoral origin placement in ALL reconstruction.

Combined Anterior and Anterolateral Stabilization of the Knee With the Iliotibial Band

Interest and knowledge on the anatomy, function, and biomechanical properties of the anterolateral ligament has led to the recognition of the importance of this structure in rotational control of the knee. This article describes a technique that allows for a combined anterior cruciate ligament (ACL) and anterolateral reconstruction, using an Iliotibial band (ITB) autograft. The graft is detached from the vastus lateralis from proximal to distal, at the center portion from ITB, preserving its distal insertion on the Gerdy tubercle. Its width is 1 cm for the distal part, used for the anterolateral ligament reconstruction, and 3 cm for the proximal part. An outside-in femoral tunnel is drilled respecting both the preferred favorable isometric femoral insertion site and the femoral ACL footprint. An ACL reconstruction combined with a lateral tenodesis with a continuous ITB graft respects the anatomical and isometric rules providing superior internal rotational control of the knee in comparison with a stand-alone ACL reconstruction.

Meniscectomy versus meniscal repair: 10 years radiological and clinical results in vertical lesions in stable knee

INTRODUCTION

Surgical management of meniscal lesion consists of either a meniscectomy or meniscal repair. Although repair offers immediate recovery after surgery, it is also associated with higher rates of revision. A meniscectomy, on the other hand is known to be associated with an early onset of osteoarthritis. The present study compared clinical and radiological results at 10 years between meniscectomy and meniscal repair in isolated vertical lesion in an otherwise stable knee. The hypothesis was that repair shows functional and radiological benefit over meniscectomy.

PATIENTS AND METHOD

A multi-centric retrospective comparative study of 32 patients (24 male, 8 female). Mean follow-up was 10.6 years (range, 10-13 years). There were 10 meniscal repairs (group R) and 22 meniscectomies (group M), in 17 right and 15 left knees. Mean age at surgery was 33.45±12.3 years (range, 9-47 years). There were 28 medial and 4 lateral meniscal lesions; 26 were in the red-red zone and 6 in red-white zone.

RESULTS

Functional score: KOOS score was significantly higher in group R than M on almost all parameters: 98±4.69 versus 77.38±21.97 for symptoms (P=0.0043), 96.89±7.20 versus 78.57±18.9 for pain (P=0.0052), 99.89±0.33 versus 80.88±19.6 for daily life activities (P=0.0002), 96.11±9.83 versus 54.05±32.85 for sport and leisure (P=0.0005), but 91±16.87 versus 68.15±37.7 for quality of life (P=0.1048). Radiology score: in group R, 7 patients had no features of osteoarthritis, and 2 had grade 1 osteoarthritis. In group M, 5 patients had grade 1 osteoarthritis, 10 grade 2, 3 grade 3 and 3 grade 4. Mean quantitative score was 0 (mean, 0.22±0.44) in-group R and 2 (mean, 2.19±0.98) in group M (P<0.0001).

DISCUSSION

At more than 10year's follow-up, functional scores were significantly better with meniscal repair than meniscectomy on all parameters of the KOOS scale except quality of life. Functional and radiological scores correlated closely. These results show that meniscal repair for vertical lesions in stable knees protects against osteoarthritis and is therefore strongly recommended.

LEVEL OF EVIDENCE

IV; retrospective study.

Meniscal survival rate after anterior cruciate ligament reconstruction

BACKGROUND

Meniscal suture provides well-documented benefits. Integrity of the cruciate ligaments of the knee is a prerequisite for meniscal healing. Nevertheless, reconstruction of the anterior cruciate ligament (ACL) does not consistently prevent recurrent tearing of a sutured meniscus. We evaluated meniscal survival rates, 5 and 10 years after meniscal suture concomitant with an ACL reconstruction. We compared the outcomes of these repaired menisci to those in which no menisci tears were detected during ACL reconstruction.

METHODS

In this multi-centric retrospective study, we included two groups. One group consists of patients who underwent a meniscal repair. This group was further divided into two subgroups based on whether follow-up was 5 years (n=76) or 10 years (n=39). The control group included 120 patients with normal menisci observed during surgery. We studied meniscal survival rates in each group, and we analyzed risk factors associated with the recurrence of meniscal lesions.

RESULTS

The 5-year meniscal survival rate was significantly higher in the control group than in the meniscal-repair group (95% vs. 80%, respectively; P=0.0029). The controls group also had a higher meniscal survival rate after 10 years, although the difference was not statistically significant (88% vs. 77%, P=0.07). A difference in knee laxity greater than 4mm was associated with a 5-fold increase in the risk of recurrent meniscal tears (P=0.0057). After 5 years, the risk of recurrence was higher for the medial than for the lateral meniscus, whereas after 10 years the difference was no longer statistically significant.

DISCUSSION

Although insufficient healing after meniscal suturing contributes to the risk of further meniscal tears, new lesions can develop in menisci that were undamaged at the time of ACL reconstruction. The risk of a new meniscal lesion is strongly associated with inadequate control of antero-posterior and rotational laxity. Some apparently "new menisci lesions" seems to have been missed during ACL reconstruction.

LEVEL OF EVIDENCE

IV, retrospective study.

Abstract A69: A novel mechanism mediates drug resistance in the exocrine-like pancreatic ductal adenocarcinoma (PDAC) subtype

PDAC is a highly aggressive disease with dismal prognosis [1, 2]. Despite extensive research and the discovery of several drug candidates, little progress has been reported since the approval of gemcitabine and erlotinib [1]. Moreover, recent trials with targeted therapies have shown only limited or no benefit [1, 2]. For a number of other carcinomas, tumor subclasses have been uncovered that allow the use of targeted therapies. The mutational landscape of PDAC is complex and heterogeneous, raising the question whether subclasses also exist in PDAC [3]. Collisson et al. described three PDAC subtypes that were identified based on their gene-expression profiles: The classical, the quasi-mesenchymal and the exocrine-like subtype [4]. However, not all subtypes could be identified in the previously available model systems. We have established a novel patient-derived model system that allows the analysis of these three human PDAC subtypes in vitro and in vivo. Hence, we provide a systematic workflow to propagate human PDAC in orthotopic xenografts and to derive tumor-initiating primary cell lines of all three PDAC subtypes. HNF-1 and Keratin 81 were identified as markers for subtype stratification by immunohistochemistry. Application of this two-marker set on a 258 large patient cohort confirmed a predominantly non-overlapping staining and revealed a significant difference in overall survival across the three subtypes. Furthermore, a drug screen uncovered subtype-specific drug sensitivities towards a number of drugs, including gemcitabine and dasatinib. Notably, the exocrine-like subtype was resistant towards all compounds tested. Thus, we aimed to identify the underlying cause of the observed drug resistance. Molecular analysis including gene set enrichment analysis (GSEA) allowed us to identify a putative novel mechanism of drug resistance. Analysis by qRT-PCR and Western blot demonstrated the enhanced expression of several genes mediating this mechanism particularly in the exocrine-like subtype in vitro and in vivo. These findings led to the identification of a novel protein target central to this mechanism. Additionally, retrospective immunohistochemical analysis of a large patient cohort confirmed that this target is predominantly found in those patient tumors classified as exocrine-like. Hence, we hypothesized that the observed strong activation of this mechanism in the exocrine-like PDAC subtype could be responsible for the drug resistance observed in this subclass. In line with this, functional inhibition of this mechanism resulted in increased drug sensitivity in the exocrine-like subtype. Hence, our findings may ultimately advance personalized treatment by applying novel marker-based patient selection strategies in combination with tailored drug use, a strategy which will be presented in more detail at the conference.

[1] Hidalgo, M. Pancreatic cancer. The New England journal of medicine. 362, 1605-1617, doi:10.1056/NEJMra0901557 (2010).

[2] Vincent, A., Herman, J., Schulick, R., Hruban, R. H. & Goggins, M. Pancreatic cancer. Lancet. 378, 607-620, doi:10.1016/S0140-6736(10)62307-0 (2011).

[3] Jones, S. et al. Core signalling pathways in human pancreatic cancers revealed by global genomic analyses. Science. 321, 1801-1806, doi:10.1126/science.1164368 (2008).

[4] Collisson, E. A. et al. Subtypes of pancreatic ductal adenocarcinoma and their differing responses to therapy. Nature medicine. 17, 500-503, doi:10.1038/nm.2344 (2011).

Citation Format: Elisa M. Noll, Christian Eisen, Elisa Espinet, Vanessa Vogel, Corinna Klein, Albrecht Stenzinger, Franziska Zickgraf, Peter Neuhaus, Marcus Bahra, Bruno V. Sinn, Christian Lutz, Michael Kulke, Andreas Pahl, Nathalia A. Giese, Oliver Strobel, Jens Werner, Wilko Weichert, Andreas Trumpp, Martin R. Sprick. A novel mechanism mediates drug resistance in the exocrine-like pancreatic ductal adenocarcinoma (PDAC) subtype. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A69.