A promoterless AAV6.2FF-based lung gene editing platform for the correction of surfactant protein B deficiency.

Surfactant protein B (SP-B) deficiency is a rare genetic disease that causes fatal respiratory failure within the first year of life. Currently, the only corrective treatment is lung transplantation. Here, we co-transduced the murine lung with adeno-associated virus 6.2FF (AAV6.2FF) vectors encoding a SaCas9-guide RNA nuclease or donor template to mediate insertion of promoterless reporter genes or the (murine) Sftpb gene in frame with the endogenous surfactant protein C (SP-C) gene, without disrupting SP-C expression. Intranasal administration of 3 × 1011 vg donor template and 1 × 1011 vg nuclease consistently edited approximately 6% of lung epithelial cells. Frequency of gene insertion increased in a dose-dependent manner, reaching 20%-25% editing efficiency with the highest donor template and nuclease doses tested. We next evaluated whether this promoterless gene editing platform could extend survival in the conditional SP-B knockout mouse model. Administration of 1 × 1012 vg SP-B-donor template and 5 × 1011 vg nuclease significantly extended median survival (p = 0.0034) from 5 days in the untreated off doxycycline group to 16 days in the donor AAV and nuclease group, with one gene-edited mouse living 243 days off doxycycline. This AAV6.2FF-based gene editing platform has the potential to correct SP-B deficiency, as well as other disorders of alveolar type II cells.

AAV-mediated delivery of actoxumab and bezlotoxumab results in serum and mucosal antibody concentrations that provide protection from C. difficile toxin challenge.

Clostridium difficile is the leading cause of antibiotic-associated nosocomial diarrhea in the developed world. When the host-associated colon microbiome is disrupted by the ingestion of antibiotics, C. difficile spores can germinate, resulting in infection. C. difficile secretes enterotoxin A (TcdA) and cytotoxin B (TcdB) that are responsible for disease pathology. Treatment options are limited as the bacterium demonstrates resistance to many antibiotics, and even with antibacterial therapies, recurrences of C. difficile are common. Actotoxumab and bezlotoxumab are human monoclonal antibodies that bind and neutralize TcdA and TcdB, respectively. In 2016, the US food and drug administration (FDA) approved bezlotoxumab for use in the prevention of C. difficile infection recurrence. To ensure the long-term expression of antibodies, gene therapy can be used. Here, adeno-associated virus (AAV)6.2FF, a novel triple mutant of AAV6, was engineered to express either actotoxumab or bezlotoxumab in mice and hamsters. Both antibodies expressed at greater than 90 µg/mL in the serum and were detected at mucosal surfaces in both models. Hundred percent of mice given AAV6.2FF-actoxumab survived a lethal dose of TcdA. This proof of concept study demonstrates that AAV-mediated expression of C. difficile toxin antibodies is a viable approach for the prevention of recurrent C. difficile infections.

Engineered AAV8 capsid acquires heparin and AVB sepharose binding capacity but has altered in vivo transduction efficiency.

Naturally occurring adeno-associated virus (AAV) serotypes that bind to ligands such as AVB sepharose or heparin can be purified by affinity chromatography, which is a more efficient and scalable method than gradient ultracentrifugation. Wild-type AAV8 does not bind effectively to either of these molecules, which constitutes a barrier to using this vector when a high throughput design is required. Previously, AAV8 was engineered to contain a SPAKFA amino acid sequence to facilitate purification using AVB sepharose resin; however, in vivo studies were not conducted to examine whether these capsid mutations altered the transduction profile. To address this gap in knowledge, a mutant AAV8 capsid was engineered to bind to AVB sepharose and heparan sulfate (AAV8-AVB-HS), which efficiently bound to both affinity columns, resulting in elution yields of >80% of the total vector loaded compared to <5% for wild-type AAV8. However, in vivo comparison by intramuscular, intravenous, and intraperitoneal vector administration demonstrated a significant decrease in AAV8-AVB-HS transduction efficiency without alteration of the transduction profile. Therefore, although it is possible to engineer AAV capsids to bind various affinity ligands, the consequences associated with mutating surface exposed residues have the potential to negatively impact other vector characteristics including in vivo potency and production yield. This study demonstrates the importance of evaluating all aspects of vector performance when engineering AAV capsids.

Antibody-based protection against respiratory syncytial virus in mice and their offspring through vectored immunoprophylaxis.

Respiratory syncytial virus (RSV) causes acute lower respiratory tract infections, with potential lower respiratory tract infections, which can be particularly problematic in infants and the elderly. There are no approved vaccines for RSV. The current standard of care for high-risk individuals is monthly administration of palivizumab, a humanized murine monoclonal antibody (mAb) targeting the RSV fusion protein. Adeno-associated virus (AAV)-mediated expression of mAbs has previously led to sustained expression of therapeutic concentrations of mAbs in several animal models, representing an alternative to repetitive passive administration. Intramuscular (IM) administration of AAV6.2FF expressing RSV antibodies, palivizumab or hRSV90, resulted in high concentrations of human (h)IgG1 mAbs in the serum and at various mucosal surfaces, while intranasal administration limited hIgG expression to the respiratory tract. IM administration of AAV6.2FF-hRSV90 or AAV6.2FF-palivizumab in a murine model provided sterilizing immunity against challenge with RSV A2. Evidence of maternal passive transfer of vectorized hRSV90 was detected in both murine and ovine models, with circulating mAbs providing sterilizing immunity in mouse progeny. Finally, addition of a "kill switch" comprised of LoxP sites flanking the mAb genes resulted in diminished serum hIgG after AAV-DJ-mediated delivery of Cre recombinase to the same muscle group that was originally transduced with the AAV-mAb vector. The ability of this AAV-mAb system to mediate robust, sustained mAb expression for maternal transfer to progeny in murine and ovine models emphasizes the potential of this platform for use as an alternative prophylactic vaccine for protection against neonatal infections, particularly in high-risk infants.

Adeno-associated virus mediated expression of monoclonal antibody MR191 protects mice against Marburg virus and provides long-term expression in sheep.

Vectored monoclonal antibody (mAb) expression mediated by adeno-associated virus (AAV) gene delivery leads to sustained therapeutic mAb expression and protection against a wide range of infectious diseases in both small and large animal models, including nonhuman primates. Using our rationally engineered AAV6 triple mutant capsid, termed AAV6.2FF, we demonstrate rapid and robust expression of two potent human antibodies against Marburg virus, MR78 and MR191, following intramuscular (IM) administration. IM injection of mice with 1 × 1011 vector genomes (vg) of AAV6.2FF-MR78 and AAV6.2FF-MR191 resulted in serum concentrations of approximately 141 µg/mL and 195 µg/mL of human IgG, respectively, within the first four weeks. Mice receiving 1 × 1011 vg (high) and 1 × 1010 vg (medium) doses of AAV6.2FF-MR191 were completely protected against lethal Marburg virus challenge. No sex-based differences in serum human IgG concentrations were observed; however, administering the AAV-mAb over multiple injection sites significantly increased serum human IgG concentrations. IM administration of three two-week-old lambs with 5 × 1012 vg/kg of AAV6.2FF-MR191 resulted in serum human IgG expression that was sustained for more than 460 days, concomitant with low levels of anti-capsid and anti-drug antibodies. AAV-mAb expression is a viable method for prolonging the therapeutic effect of recombinant mAbs and represents a potential alternative "vaccine" strategy for those with compromised immune systems or in possible outbreak response scenarios.

Primary prevention of ovarian cancer: a patient decision aid for opportunistic salpingectomy.

BACKGROUND: The discovery of the fallopian tube epithelium as the origin of high-grade serous ovarian cancer has brought a new option for ovarian cancer prevention. The fallopian tubes have no known function after completion of childbearing and can be removed to reduce the lifetime risk of ovarian cancer. Although the lifetime risk in the general population does not justify preventive surgery in itself, salpingectomy can be performed during abdominal surgery for other indications, also known as an opportunistic salpingectomy. The popularity of opportunistic salpingectomy is increasing worldwide; however, the variation between gynecologists and hospitals in their advice on opportunistic salpingectomy occurs because of the remaining uncertainty of evidence. Therefore, whether a woman can make her own decision depends on the hospital or gynecologist she visits. We aimed to lower this practice variation by providing standardized and unbiased counseling material. OBJECTIVE: We aimed to develop and test a patient decision aid for opportunistic salpingectomy in women undergoing pelvic gynecologic surgery to either retain the ovaries or opt for sterilization. STUDY DESIGN: We followed a systematic development process based on the International Patient Decision Aid Standards. Data were collected between June 2019 and June 2020, using both qualitative and quantitative methods. The development process that occurred in collaboration with patients and healthcare professionals was overseen by a multidisciplinary steering group and was divided into 4 phases: (1) assessment of decisional needs using individual telephone interviews and questionnaires; (2) development of content and format based on decisional needs, current literature, and guidelines; (3) alpha testing and the first revision round; and (4) alpha testing and the second revision round. RESULTS: An outline of the patient decision aid was developed on the basis of decisional needs, current literature, and guidelines. It became clear that the decision aid should consist of 2 separate paths: one with information specifically for salpingectomy in addition to abdominal surgery and one for salpingectomy as a sterilization method. Both paths contained information on the anatomy and function of ovaries and fallopian tubes, risk reduction of ovarian cancer, and potential benefits and risks of opportunistic salpingectomy. Moreover, the sterilization path contains information on various sterilization methods and risks of unwanted pregnancy. The patient decision aid was developed as an online tool that includes information chapters, a knowledge quiz, consideration statements, and a summary detailing the patient's preferences and considerations. Adjustments were made following alpha testing round 1. The improved patient decision aid was subjected to usability tests (alpha testing round 2), in which it scored an "excellent" in tests with patients and a "good" in tests with gynecologists. Furthermore, our patient decision aid met the requirements of 45 of 49 applicable items from the International Patient Decision Aid Standards criteria. CONCLUSION: In collaboration with patients and healthcare professionals, a patient decision aid was developed on opportunistic salpingectomy and salpingectomy as a sterilization method. Both patients and gynecologists believed it is a useful tool that supports patients in making an informed decision whether to undergo an opportunistic salpingectomy and supports the counseling process by gynecologists.

Patients' and professionals' perspectives on implementation of opportunistic salpingectomy: a mixed-method study.

BACKGROUND: To prevent ovarian cancer, several international societies have issued guidelines which recommend to discuss opportunistic salpingectomy with women undergoing pelvic surgery after completion of childbearing. The opportunistic salpingectomy refers to the additional removal of Fallopian tubes during pelvic surgery for another indication to reduce the risk of developing ovarian cancer. These recommendations emphasize the importance of counselling on benefits and risks of opportunistic salpingectomy but offer no guidance on their implementation in daily practice. The lack of a tailored implementation strategy has resulted in a wide variation in current practice. To reduce this practice variation, we identified influencing factors on implementing opportunistic salpingectomy from patients' and professionals' perspectives. METHODS: We conducted a mixed-method study between 2019 and 2020 throughout the Netherlands. In a qualitative phase, we conducted interviews with gynecologic patients (N = 11) and their professionals (N = 20) to explore barriers and facilitators, using an interview guide. In the quantitative phase, we quantified these barriers and facilitators among patients who underwent a hysterectomy or sterilization and were counselled on the opportunistic salpingectomy (N = 77), and members of the Dutch Society of Obstetrics and Gynecology (N = 204), using questionnaires. For both phases, barriers and facilitators were classified into the following domains: innovation, patient, healthcare professional, social setting, organization, and economic and political context. RESULTS: For patients, main barriers were lack of knowledge about: the existence of the opportunistic salpingectomy (45%), size of the surgery (44%) and its associated possible disadvantages (37%). In addition, patients attributed their reluctance to concerns about the removal of healthy organs (46%). For professionals, main barriers were: patients' lack of knowledge of the size of surgery (85%) and its associated possible disadvantages (77%), the gap in evidence on long term risks and benefits (43%), the lack of feasibility in certain patients and during vaginal surgery (66%). Both patients (41%) and professionals (67%) identified the need for counselling material as facilitator. CONCLUSION: To reduce the variety in care regarding opportunistic salpingectomy, consensus and uniform counselling is needed. Including the opportunistic salpingectomy in gynecological guidelines and a decision aid for counselling could serve as tools to facilitate implementation.

Hysterectomy with opportunistic salpingectomy versus hysterectomy alone.

BACKGROUND: Ovarian cancer has the highest mortality rate of all gynaecological malignancies with an overall five-year survival rate of 30% to 40%. In the past two decades it has become apparent and more commonly accepted that a majority of ovarian cancers originate in the fallopian tube epithelium and not from the ovary itself. This paradigm shift introduced new possibilities for ovarian cancer prevention. Salpingectomy during a hysterectomy for benign gynaecological indications (also known as opportunistic salpingectomy) might reduce the overall incidence of ovarian cancer. Aside from efficacy, safety is of utmost importance, especially due to the preventive nature of opportunistic salpingectomy. Most important are safety in the form of surgical adverse events and postoperative hormonal status. Therefore, we compared the benefits and risks of hysterectomy with opportunistic salpingectomy to hysterectomy without opportunistic salpingectomy. OBJECTIVES: To assess the effect and safety of hysterectomy with opportunistic salpingectomy versus hysterectomy without salpingectomy for ovarian cancer prevention in women undergoing hysterectomy for benign gynaecological indications; outcomes of interest include the incidence of epithelial ovarian cancer, surgery-related adverse events and postoperative ovarian reserve. SEARCH METHODS: The Cochrane Gynaecology and Fertility (CGF) Group trials register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL and two clinical trial registers were searched in January 2019 together with reference checking and contact with study authors. SELECTION CRITERIA: We intended to include both randomised controlled trials (RCTs) and non-RCTs that compared ovarian cancer incidence after hysterectomy with opportunistic salpingectomy to hysterectomy without opportunistic salpingectomy in women undergoing hysterectomy for benign gynaecological indications. For assessment of surgical and hormonal safety, we included RCTs that compared hysterectomy with opportunistic salpingectomy to hysterectomy without opportunistic salpingectomy in women undergoing hysterectomy for benign gynaecological indications. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures recommended by Cochrane. The primary review outcomes were ovarian cancer incidence, intraoperative and short-term postoperative complication rate and postoperative hormonal status. Secondary outcomes were total surgical time, estimated blood loss, conversion rate to open surgery (applicable only to laparoscopic and vaginal approaches), duration of hospital admission, menopause-related symptoms and quality of life. MAIN RESULTS: We included seven RCTs (350 women analysed). The evidence was of very low to low quality: the main limitations being a low number of included women and surgery-related adverse events, substantial loss to follow-up and a large variety in outcome measures and timing of measurements.No studies reported ovarian cancer incidence after hysterectomy with opportunistic salpingectomy compared to hysterectomy without opportunistic salpingectomy in women undergoing hysterectomy for benign gynaecological indications. For surgery-related adverse events, there were insufficient data to assess whether there was any difference in both intraoperative (odds ratio (OR) 0.66, 95% confidence interval (CI) 0.11 to 3.94; 5 studies, 286 participants; very low-quality evidence) and short-term postoperative (OR 0.13, 95% CI 0.01 to 2.14; 3 studies, 152 participants; very low-quality evidence) complication rates between hysterectomy with opportunistic salpingectomy and hysterectomy without opportunistic salpingectomy because the number of surgery-related adverse events was very low. For postoperative hormonal status, the results were compatible with no difference, or with a reduction in anti-Müllerian hormone (AMH) that would not be clinically relevant (mean difference (MD) -0.94, 95% CI -1.89 to 0.01; I2 = 0%; 5 studies, 283 participants; low-quality evidence). A reduction in AMH would be unfavourable, but due to wide CIs, the postoperative change in AMH can still vary from a substantial decrease to even a slight increase. AUTHORS' CONCLUSIONS: There were no eligible studies reporting on one of our primary outcomes - the incidence of ovarian cancer specifically after hysterectomy with or without opportunistic salpingectomy. However, outside the scope of this review there is a growing body of evidence for the effectiveness of opportunistic salpingectomy itself during other interventions or as a sterilisation technique, strongly suggesting a protective effect. In our meta-analyses, we found insufficient data to assess whether there was any difference in surgical adverse events, with a very low number of events in women undergoing hysterectomy with and without opportunistic salpingectomy. For postoperative hormonal status we found no evidence of a difference between the groups. The maximum difference in time to menopause, calculated from the lower limit of the 95% CI and the natural average AMH decline, would be approximately 20 months, which we consider to be not clinically relevant. However, the results should be interpreted with caution and even more so in very young women for whom a difference in postoperative hormonal status is potentially more clinically relevant. Therefore, there is a need for research on the long-term effects of opportunistic salpingectomy during hysterectomy, particularly in younger women, as results are currently limited to six months postoperatively. This limit is especially important as AMH, the most frequently used marker for ovarian reserve, recovers over the course of several months following an initial sharp decline after surgery. In light of the available evidence, addition of opportunistic salpingectomy should be discussed with each woman undergoing a hysterectomy for benign indication, with provision of a clear overview of benefits and risks.

Intramuscular Adeno-Associated Virus-Mediated Expression of Monoclonal Antibodies Provides 100% Protection Against Ebola Virus Infection in Mice.

The 2013-2016 West Africa outbreak demonstrated the epidemic potential of Ebola virus and highlighted the need for counter strategies. Monoclonal antibody (mAb)-based therapies hold promise as treatment options for Ebola virus infections. However, production of clinical-grade mAbs is labor intensive, and immunity is short lived. Conversely, adeno-associated virus (AAV)-mediated mAb gene transfer provides the host with a genetic blueprint to manufacture mAbs in vivo, leading to steady release of antibody over many months. Here we demonstrate that AAV-mediated expression of nonneutralizing mAb 5D2 or 7C9 confers 100% protection against mouse-adapted Ebola virus infection, while neutralizing mAb 2G4 was 83% protective. A 2-component cocktail, AAV-2G4/AAV-5D2, provided complete protection when administered 7 days prior to challenge and was partially protective with a 3-day lead time. Finally, AAV-mAb therapies provided sustained protection from challenge 5 months following AAV administration. AAV-mAb may be a viable alternative strategy for vaccination against emerging infectious diseases.

AAV vector distribution in the mouse respiratory tract following four different methods of administration.

BACKGROUND: Targeted delivery of gene therapy vectors to the mouse respiratory tract is often performed via intranasal or intratracheal administration; however, there can be a great deal of variability between these methods, which could potentially influence experimental results. Improving the accuracy and precision of lung delivery will not only reduce the number of animals required to detect statistically significant differences, but may reduce the variability of studies from different laboratories. RESULTS: Here we evaluated three different methods of adeno-associated virus (AAV) vector administration to the respiratory tract in mice (intranasal, intubation, and intratracheal injection) and discuss the advantages, challenges, and shortcomings of each. We also present a modified-intranasal delivery technique that is superior to passive administration of vector into the nares of anesthetized supine animals. Transgene expression was consistently visible in the nasal cavity, trachea, and proximal to middle aspect of all lung lobes for all four methods, whereas transgene expression was consistently observed in the most distal aspect of lung lobes only with the intubation and intratracheal injection techniques. AAV vector genome copy numbers in the lung were approximately four-fold lower in mice that received vector via intranasal administration in comparison to the other three methods of vector delivery. The modified intranasal, intubation and intratracheal injection methods of vector administration did not yield statistical differences in AAV vector genome copy numbers in the lung. With regard to reproducibility of vector distribution within and between animals, the modified-intranasal technique was superior. CONCLUSION: Our results show that mode of AAV vector administration to the murine respiratory tract should be selected based on desired target site and skill of the researcher, and that appropriate technique selection may greatly influence experimental outcomes.

An Improved Helper Plasmid Containing Deletions Within the E4 and E2a Genes Results in Increased Adeno-Associated Virus Productivity.

The use of a helper plasmid to replace adenovirus infection for adeno-associated virus (AAV) manufacturing has been common practice for decades. Adenovirus E4, E2a, and VA RNA genes are sufficient to support efficient AAV replication. In an effort to ensure that all transfected DNA has a functional role in AAV production, deletions were introduced to the E4 and E2a genes to determine if any portions were dispensable. Although a 900 bp deletion in the E2a intron did not have an impact, the removal of open reading frames (orf) 1-4 from the E4 gene resulted in a doubling of AAV productivity. The E4Δorf1-4 deletion was associated with a reduction in E4orf6 transcripts, along with an increase in Rep and Cap transcripts and protein levels, which corresponded to increased AAV productivity in crude lysate. The final product of these studies was a helper plasmid, termed OXB-Helper_3, that is >3.4 kb smaller than the original control plasmid and resulted in ∼2× improvement in vector genome productivity across multiple capsid serotypes, genome designs, and transfection platforms.

AAV Vectors Pseudotyped with Capsids from Porcine and Bovine Species Mediate In Vitro and In Vivo Gene Delivery.

Adeno-associated virus (AAV) vectors are among the most widely used delivery vehicles for in vivo gene therapy as they mediate robust and sustained transgene expression with limited toxicity. However, a significant impediment to the broad clinical success of AAV-based therapies is the widespread presence of pre-existing humoral immunity to AAVs in the human population. This immunity arises from the circulation of non-pathogenic endemic human AAV serotypes. One possible solution is to use non-human AAV capsids to pseudotype transgene-containing AAV vector genomes of interest. Due to the low probability of human exposure to animal AAVs, pre-existing immunity to animal-derived AAV capsids should be low. Here, we characterize two novel AAV capsid sequences: one derived from porcine colon tissue and the other from a caprine adenovirus stock. Both AAV capsids proved to be effective transducers of HeLa and HEK293T cells in vitro. In vivo, both capsids were able to transduce the murine nose, lung, and liver after either intranasal or intraperitoneal administration. In addition, we demonstrate that the porcine AAV capsid likely arose from multiple recombination events involving human- and animal-derived AAV sequences. We hypothesize that recurrent recombination events with similar and distantly related AAV sequences represent an effective mechanism for enhancing the fitness of wildtype AAV populations.

A novel dual-plasmid platform provides scalable transfection yielding improved productivity and packaging across multiple AAV serotypes and genomes.

Transient transfection of mammalian cells using plasmid DNA is a standard method to produce adeno-associated virus (AAV) vectors allowing for flexible and scalable manufacture. Typically, three plasmids are used to encode the necessary components to facilitate vector production; however, a dual-plasmid system, termed pDG, was introduced over 2 decades ago demonstrating two components could be combined resulting in comparable productivity to triple transfection. We have developed a novel dual-plasmid system, pOXB, with an alternative arrangement of sequences that results in significantly increased AAV vector productivity and percentage of full capsids packaged in comparison to the pDG dual design and triple transfection. Here, we demonstrate the reproducibility of these findings across seven recombinant AAV genomes and multiple capsid serotypes as well as the scalability of the pOXB dual-plasmid transfection at 50-L bioreactor scale. Purified drug substance showed a consistent product quality profile in line with triple-transfected vectors, except for a substantial improvement in intact genomes packaged using the pOXB dual- transfection system. Furthermore, pOXB dual- and triple-transfection-based vectors performed consistently in vivo. The pOXB dual plasmid represents an innovation in AAV manufacturing resulting in significant process gains while maintaining the flexibility of a transient transfection platform.

AAV-monoclonal antibody expression protects mice from Ebola virus without impeding the endogenous antibody response to heterologous challenge.

Filoviruses cause severe hemorrhagic fever with case fatality rates as high as 90%. Filovirus-specific monoclonal antibodies (mAbs) confer protection in nonhuman primates as late as 5 days after challenge, and FDA-approved mAbs REGN-EB3 and mAb114 have demonstrated efficacy against Ebola virus (EBOV) infection in humans. Vectorized antibody expression mediated by adeno-associated virus (AAV) can generate protective and sustained concentrations of therapeutic mAbs in animal models for a variety of infectious diseases, including EBOV. Here we demonstrate that AAV6.2FF-mediated expression of murine IgG2a EBOV mAbs, 2G4 and 5D2, protects from mouse-adapted (MA)-EBOV infection with none of the surviving mice developing anti-VP40 antibodies above background. Protective serum concentrations of AAV6.2FF-2G4/AAV6.2FF-5D2 did not alter endogenous antibody responses to heterologous virus infection. AAV-mediated expression of EBOV mAbs 100 and 114, and pan-ebolavirus mAbs, FVM04, ADI-15878, and CA45, as human IgG1 antibodies conferred protection against MA-EBOV at low serum concentrations, with minimum protective serum levels as low as 2 µg/mL. Vectorized expression of murine IgG2a or human IgG1 mAbs led to sustained expression in the serum of mice for >400 days or for the lifetime of the animal, respectively. AAV6.2FF-mediated mAb expression offers an alternative to recombinant antibody administration in scenarios where long-term protection is preferable to passive immunization.

Natural variations in AAVHSC16 significantly reduce liver tropism and maintain broad distribution to periphery and CNS.

Adeno-associated viruses derived from human hematopoietic stem cells (AAVHSCs) are naturally occurring AAVs. Fifteen AAVHSCs have demonstrated broad biodistribution while displaying differences in transduction. We examine the structure-function relationships of these natural amino acid variations on cellular binding. We demonstrate that AAVHSC16 is the only AAVHSC that does not preferentially bind to terminal galactose. AAVHSC16 contains two unique amino acids, 501I and 706C, compared with other AAVHSCs. Through mutagenesis, we determined that residue 501 contributes to the lack of galactose binding. Structural analysis revealed that residue 501 is in proximity to the galactose binding pocket, hence confirming its functional role in galactose binding. Biodistribution analysis of AAVHSC16 indicated significantly less liver tropism in mice and non-human primates compared with other clade F members, likely associated with overall binding differences observed in vitro. AAVHSC16 maintained robust tropism to other key tissues in the peripheral and central nervous systems after intravenous injection, including to the brain, heart, and gastrocnemius. Importantly, AAVHSC16 did not induce elevated liver enzyme levels in non-human primates after intravenous injection at high doses. The unique glycan binding and tropism of AAVHSC16 makes this naturally occurring capsid an attractive candidate for therapies requiring less liver tropism while maintaining broad biodistribution.

Functional estrogen receptor signaling pathway activity in high-grade serous ovarian carcinoma as compared to estrogen receptor protein expression by immunohistochemistry.

PURPOSE: Anti-estrogen therapy may be used as a palliative treatment option in high-grade serous ovarian carcinomas (HGSC). However, clinical implementation is limited as the use of estrogen receptor (ER) protein expression by immunohistochemistry remains insufficient in predicting therapy response. To determine the accuracy of ER protein expression as a marker for ER signaling pathway activity, we aimed to correlate ER protein expression to functional ER signaling pathway activity in HGSC. METHODS: Immunohistochemical ER protein expression was visually scored using total percentages of stained tumor cells and histoscores. Subsequently, mRNA was extracted, and RT-qPCR analysis was performed. Functional ER pathway activity was assessed by a computational Bayesian model inferring ER signaling pathway activity from mRNA levels of ER-specific target genes. RESULTS: Our analysis of 29 HGSCs shows that neither total percentage of ER protein expression, nor ER histoscores are significantly correlated to ER signaling pathway activity (respectively, p = 0.473 and p = 0.606). Classification of HGSC into three groups based on ER histoscores 0-100 (n = 6), 101-200 (n = 15) and 201-300 (n = 8) resulted in comparable mean ER signaling pathway activity among the groups (p = 0.356). Several samples in the higher ER histoscore groups had low ER signaling pathway activity, indicating that nuclear ER protein expression is not sufficient to describe transcriptional ER activation. CONCLUSION: Positive immunohistochemical ER staining is not always indicative of an active ER signaling pathway and is, therefore, a poor predictor of anti-estrogen response. Further research is needed to prove the predictive value of ER signaling pathway activity regarding anti-estrogen sensitivity in HGSC patients.

Survival Is Related to Estrogen Signal Transduction Pathway Activity in Postmenopausal Women Diagnosed with High-Grade Serous Ovarian Carcinoma.

High-grade serous ovarian carcinoma (HGSC), the most common subtype of ovarian cancer, has a high mortality rate. Although there are some factors associated with survival, such as stage of disease, there are remarkable differences in survival among women diagnosed with advanced stage disease. In this study, we investigate possible relations between survival and signal transduction pathway (STP) activity. We assessed the functional activity of the androgen receptor (AR), estrogen receptor (ER), phosphoinositide-3-kinase (PI3K), Hedgehog (HH), transforming growth factor beta (TGF-ß) and canonical wingless-type MMTV integration site (Wnt) pathway in 85 primary tumor samples of patients with FIGO stage IIIC to IVB HGSC and disease-free survival (DFS) below 12 (n = 52) or over 24 months (n = 33). There were no significant differences in median pathway activity between patients with a short and long DFS. In univariate Cox proportional hazards analysis, ER pathway activity was related to a favorable DFS and overall survival (OS) in postmenopausal women (p = 0.033 and p = 0.041, respectively), but not in premenopausal women. We divided the postmenopausal group into subgroups based on ER pathway activity quartiles. Survival analysis revealed that postmenopausal women in the lowest ER quartile had a shorter DFS and OS (log-rank p = 0.006 and p < 0.001, respectively). Furthermore, we were able to form subgroups of patients based on an inverse relation between ER and PI3K pathway activity. In conclusion, in postmenopausal patients with advanced stage HGSC, a poorer survival outcome was associated with low functional ER pathway activity.

Safety and Tolerability of the Adeno-Associated Virus Vector, AAV6.2FF, Expressing a Monoclonal Antibody in Murine and Ovine Animal Models.

Adeno-associated virus (AAV) vector mediated expression of therapeutic monoclonal antibodies is an alternative strategy to traditional vaccination to generate immunity in immunosuppressed or immunosenescent individuals. In this study, we vectorized a human monoclonal antibody (31C2) directed against the spike protein of SARS-CoV-2 and determined the safety profile of this AAV vector in mice and sheep as a large animal model. In both studies, plasma biochemical parameters and hematology were comparable to untreated controls. Except for mild myositis at the site of injection, none of the major organs revealed any signs of toxicity. AAV-mediated human IgG expression increased steadily throughout the 28-day study in sheep, resulting in peak concentrations of 21.4-46.7 µg/ mL, demonstrating practical scale up from rodent to large animal models. This alternative approach to immunity is worth further exploration after this demonstration of safety, tolerability, and scalability in a large animal model.