Feasibility evaluation of novel AI-based deep-learning contouring algorithm for radiotherapy.

PURPOSE: To evaluate the clinical feasibility of the Siemens Healthineers AI-Rad Companion Organs RT VA30A (Organs-RT) auto-contouring algorithm for organs at risk (OARs) of the pelvis, thorax, and head and neck (H&N). METHODS: Computed tomography (CT) datasets from 30 patients (10 pelvis, 10 thorax, and 10 H&N) were collected. Four sets of OARs were generated on each scan, one set by Organs-RT and the others by three experienced users independently. A physician (expert) then evaluated each contour by assigning a score from the following scale: 1-Must Redo, 2-Major Edits, 3-Minor Edits, 4-Clinically usable. Using the highest-scored OAR from the human users as a reference, the contours generated by Organs-RT were evaluated via Dice Similarity Coefficient (DSC), Hausdorff Distance (HDD), Mean Distance to Agreement (mDTA), Volume comparison, and visual inspection. Additionally, each human user recorded the time to delineate each structure set and time-saving efficiency was measured. RESULTS: The average DSC obtained for the pelvic OARs ranged between (0.81 ± 0.06)Rectum and (0.94 ± 0.03)Bladder . (0.75 ± 0.09)Esophagus to ( 0.96 ± 0.02 ) Rt . Lung ${( {0.96 \pm 0.02} )}_{{\mathrm{Rt}}.{\mathrm{\ Lung}}}$ for the thoracic OARs and (0.66 ± 0.07)Lips to (0.83 ± 0.04)Brainstem for the H&N. The average HDD in cm for the pelvis cohort ranged between (0.95 ± 0.35)Bladder to (3.62 ± 2.50)Rectum , (0.42 ± 0.06)SpinalCord to (2.09 ± 2.00)Esophagus for the thoracic set and ( 0.53 ± 0.22 ) Cerv _ SpinalCord ${( {0.53 \pm 0.22} )}_{{\mathrm{Cerv}}\_{\mathrm{SpinalCord}}}$ to (1.50 ± 0.50)Mandible for the H&N region. The time-saving efficiency was 67% for H&N, 83% for pelvis, and 84% for thorax. 72.5%, 82%, and 50% of the pelvis, thorax, and H&N OARs were scored as clinically usable by the expert, respectively. CONCLUSIONS: The highest agreement registered between OARs generated by Organs-RT and their respective references was for the bladder, heart, lungs, and femoral heads, with an overall DSC≥0.92. The poorest agreement was for the rectum, esophagus, and lips, with an overall DSC⩽0.81. Nonetheless, Organs-RT serves as a reliable auto-contouring tool by minimizing overall contouring time and increasing time-saving efficiency in radiotherapy treatment planning.

Minimal Cerebrospinal Fluid Concentration of Miltefosine despite Therapeutic Plasma Levels during the Treatment of Amebic Encephalitis.

Miltefosine is an alkylphosphocholine compound that is used primarily for treatment of leishmaniasis and demonstrates in vitro and in vivo antiamebic activity against Acanthamoeba species. Recommendations for treatment of amebic encephalitis generally include miltefosine therapy. Data indicate that treatment with an amebicidal concentration of at least 16 µg/ml of miltefosine is required for most Acanthamoeba species. Although there is a high level of mortality associated with amebic encephalitis, a paucity of data regarding miltefosine levels in plasma and cerebrospinal fluid in vivo exists in the literature. We found that despite aggressive dosing (oral miltefosine 50 mg every 6 h) and therapeutic plasma levels, the miltefosine concentration in cerebrospinal fluid was negligible in a patient with AIDS and Acanthamoeba encephalitis.

Design and synthesis of potent RSK inhibitors.

Utilizing the already described 3,4-bi-aryl pyridine series as a starting point, incorporation of a second ring system with a hydrogen bond donor and additional hydrophobic contacts yielded the azaindole series which exhibited potent, picomolar RSK2 inhibition and the most potent in vitro target modulation seen thus far for a RSK inhibitor. In the context of the more potent core, several changes at the phenol moiety were assessed to potentially find a tool molecule appropriate for in vivo evaluation.

Development, Implementation, and Use of a Process to Promote Knowledge Translation in Rehabilitation.

OBJECTIVE: To examine the use and effect of the Battery of Rehabilitation Assessments and Interventions on evidence-based practice (EBP) over 6 years. DESIGN: Successive independent samples study. SETTING: Large rehabilitation system. PARTICIPANTS: Successive samples of allied health clinicians (N=372) in 2009 (n=136), 2012 (n=115), and 2015 (n=121). INTERVENTIONS: The Battery of Rehabilitation Assessments and Interventions includes 2 components: (1) a process to synthesize, adapt, and make recommendations about the application of evidence; and (2) a process to implement the recommended practices in 3 levels of care. MAIN OUTCOME MEASURES: To assess the effect of the project, surveys on EBP perspectives, use, and barriers were conducted before Battery of Rehabilitation Assessments and Interventions implementation and 3 and 6 years after implementation. Questions about effect of the project on clinical practice were included 3 and 6 years postimplementation. RESULTS: Survey data indicate the Battery of Rehabilitation Assessments and Interventions resulted in a significant increase in use of EBPs to make clinical decisions and justify care. As a result of the project, survey participants reported a substantial increase in use of outcome measures in 2012 (74%) and 2015 (91%) and evidence-based interventions in 2012 (62%) and 2015 (82%). In 2012, significant differences (P≤.01) in effect of the Battery of Rehabilitation Assessments and Interventions on practice were identified between therapists who were directly involved in the project and Interventions compared with uninvolved therapists. In 2015, no significant differences existed between involved and uninvolved therapists. CONCLUSIONS: After 6 years of sustained implementation efforts, the Battery of Rehabilitation Assessments and Interventions expedited the adoption of EBPs throughout a large system of care in rehabilitation.

Dosing, administration, and safety of radium-223: How I do it.

Radium-223 dichloride is a first-in-class bone-directed radiopharmaceutical that has been shown to prolong survival in men with metastatic castrate resistant prostate cancer (mCRPC). Unlike other radiopharmaceuticals, radium-223 uniquely uses alpha-emission to deliver high intensity, short range cytoxic treatments resulting in minimal myelosuppression. Following the results of the ALSYMPCA trial, radium-223 (Xofigo) was FDA approved in the United States in May 2013 and approved by Health Canada in December 2013 for the treatment of mCRPC with symptomatic bone metastases and no visceral disease. This 'How I do it' article describes the background of radium 223 as well as the methods and techniques that our institution uses for safe and effective administration and notes the subtle differences when administering the drug in Canada.

2-Amino-7-substituted benzoxazole analogs as potent RSK2 inhibitors.

2-Amino-7-substituted benzoxazole analogs were identified by HTS as inhibitors of RSK2. Molecular modeling and medicinal chemistry techniques were employed to explore the SAR for this series with a focus of improving in vitro and target modulation potency and physicochemical properties.

Practical guide to the use of radium 223 dichloride.

INTRODUCTION: Bone seeking radiopharmaceuticals have been used for decades in the palliation of pain from bone metastases emerging from prostate cancer. Recent clinical evidence has demonstrated an improved survival in men with metastatic castration resistant prostate cancer (CRPC) with radium 223. MATERIAL AND METHODS: A review of the literature was performed to identify the role of radiopharmaceuticals in the management of prostate cancer. We focused on prospective trials in order to identify the highest level of evidence describing this therapy. Further, we focused on providing a clinical guide for the use of radium 223. RESULTS: The phase III ALSYMPCA trial which compared radium 223 to placebo in men with symptomatic CRPC demonstrated a statistically significant improvement in median overall survival of 3.6 months and an improvement in time to first skeletal related event. There were higher rates of myelosuppression and diarrhea with radium 223, however, no clinically meaningful differences in the frequency of grade 3 or 4 adverse events were observed between the study groups. CONCLUSION: Radium 223 is a safe and effective therapy in men with symptomatic CRPC providing a survival advantage on par with novel antiandrogens, CYP-17 inhibitors, and chemotherapy. Radium 223 has huge potential in combination strategies as well as for use earlier in the natural history of metastatic prostate cancer.

Early arterial stasis during resin-based yttrium-90 radioembolization: incidence and preliminary outcomes.

OBJECTIVES: This study was conducted to determine the incidence of early stasis in radioembolization using resin yttrium-90 (Y-90) microspheres, to evaluate potential contributing factors, and to review initial imaging outcomes. METHODS: Patients in whom early stasis occurred were compared with those in whom complete delivery was achieved for tumour type and vascularity, tumour : normal liver ratio (T : N ratio) at technetium-99m-macroaggregated albumin (Tc-99m-MAA) angiography, previous intra-arterial therapy, and infusion site (left, right or whole liver). Tumour response was evaluated at 3 months and defined according to whether a partial response and stable disease versus progressive disease were demonstrated. RESULTS: A total of 71 patients underwent 128 Y-90 infusions in which 26 (20.3%) stasis events occurred. Hypervascular and hypovascular tumours had similar rates of stasis (17.4% versus 27.8%; P = NS). The mean ± standard deviation T : N ratio was 3.03 ± 1.54 and 3.66 ± 2.79 in patients with and without stasis, respectively (P = NS). Stasis occurred in 14 of 81 (17.3%) and 12 of 47 (25.5%) infusions following previous intra-arterial therapy and in therapy-naïve territories, respectively (P = NS). Early stasis occurred in 15 of 41 (36.6%) left, 10 of 65 (15.4%) right and one of 22 (4.5%) whole liver infusions (P < 0.001). Rates of partial response and stable disease were similar in the stasis (88.3%) and non-stasis (76.0%) groups (P = NS). CONCLUSIONS: Early stasis occurred in approximately 20% of infusions with similar incidences in hyper- and hypovascular tumours. Whole-liver therapy reduced the incidence of stasis. Stasis did not appear to affect initial imaging outcomes.

T cell intrinsic STAT1 signaling prevents aberrant Th1 responses during acute toxoplasmosis.

Infection-induced T cell responses must be properly tempered and terminated to prevent immuno-pathology. Using transgenic mice, we demonstrate that T cell intrinsic STAT1 signaling is required to curb inflammation during acute infection with Toxoplasma gondii. Specifically, we report that mice lacking STAT1 selectively in T cells expel parasites but ultimately succumb to lethal immuno-pathology characterized by aberrant Th1-type responses with reduced IL-10 and increased IL-13 production. We also find that, unlike STAT1, STAT3 is not required for induction of IL-10 or suppression of IL-13 during acute toxoplasmosis. Each of these findings was confirmed in vitro and ChIP-seq data mining showed that STAT1 and STAT3 co-localize at the Il10 locus, as well as loci encoding other transcription factors that regulate IL-10 production, most notably Maf and Irf4. These data advance basic understanding of how infection-induced T cell responses are managed to prevent immuno-pathology and provide specific insights on the anti-inflammatory properties of STAT1, highlighting its role in shaping the character of Th1-type responses.

Development of a UPLC-MRM-based targeted proteomic method to profile subcellular organelle marker proteins from human liver tissues.

Subcellular organelles have long been an interest in biochemical research and drug development as the isolation of those organelles can help to probe protein functions and elucidate drug disposition within the cell. Usually, the purity of isolated subcellular organelle fractions was determined using immunoblot analysis of subcellular organelle marker proteins, which can be labor-intensive and lack reproducibility due to antibody batch-to-batch variability. As such, a higher throughput and more robust method is needed. Here, a UPLC-MRM-based targeted proteomic method was developed for a panel of human organelle marker proteins and used to profile a series of sucrose fractions isolated from the protein extract of human liver tissues. The method was validated by comparing to the traditional immunoblot and determining subcellular localization of three case study proteins (CYP3A4, FcRn, and ß2M) pertaining to the disposition of small molecule and biologic drugs. All three case study proteins were co-enriched with their corresponding subcellular protein marker, and complete recoveries were achieved from isolated fractions. This newly developed MRM method for the panel of human organelle marker proteins can potentially accelerate future intracellular drug disposition analysis and facilitate subcellular organelle quality assessment.

Well-rounded pharmacists: a longitudinal evaluation of a multi-sector pre-registration programme.

INTRODUCTION: Pharmacists traditionally work in either hospital or community settings and increasingly in primary care. As demands on health care continue to rise, pharmacists need a well-rounded understanding of the patient journey and transfer of care and be capable of working in any setting. In response, Health Education and Improvement Wales (HEIW) launched a multi-sector pre-registration pharmacy training programme. Trainees experience all three pharmacy settings throughout the year, in contrast to the traditional, single-sector programmes. OBJECTIVES: To explore the views of the now-qualified pharmacists, their tutors and line managers on the multi-sector programme and how it prepares pharmacists for practice. METHODS: This longitudinal study followed pharmacists through the multi-sector programme, to approximately 1 year post-registration. Data were collected via interviews (n = 27) with pharmacists, tutors and line managers. All data were pattern coded and analysed thematically. KEY FINDINGS: Pharmacists maintained that they benefited from the multi-sector training programme and would choose this option again. Pharmacists, tutors and line managers considered that the programme provided a more holistic perspective of pharmacy than single-sector programmes and a greater understanding of patient journeys and transfer of care. Nonetheless, there remains a lack of consensus on how the programme is best structured, and there is scope to increase the hands-on experience in primary care settings. CONCLUSIONS: Greater communication across sectors and smoother transfer of patient care benefit employers and patients as well as the pharmacists. Recommendations for future multi-sector programmes are suggested.

Toxicities after radioembolization with yttrium-90 SIR-spheres: incidence and contributing risk factors at a single center.

PURPOSE: To report the incidence of liver function test (LFT) toxicities after radioembolization with yttrium-90 ((90)Y) SIR-Spheres and review potential risk factors. MATERIALS AND METHODS: Patients receiving (90)Y for radioembolization of primary or metastatic liver tumors had follow-up LFTs 29-571 days after treatment. The incidence and duration of bilirubin, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) toxicities were documented using common terminology criteria. Factors that were assessed included previous intra-arterial (IA) therapy, systemic chemotherapy, low tumor-to-normal liver tissue ratio at mapping angiography, vascular stasis, and higher prescribed (90)Y doses. RESULTS: There were 81 patients who underwent 122 infusions and had follow-up LFTs. Of 122 infusions, 71 (58%) were associated with toxicity. One patient died with radiation-induced liver disease. Grade 3 or greater toxicities occurred in seven (7%) patients after nine procedures. The median durations of laboratory elevations for bilirubin, AST, and ALT were 29 days, 29 days, and 20 days. Toxicity developed after 51 (71%) of 72 infusions with previous IA therapy versus 20 (40%) of 50 infusions in treatment-naïve areas (P = .0006). Absence of previous systemic therapy was associated with greater risk of toxicity versus previous chemotherapy (47% vs 66%, P = .03). Other factors were not associated with increased toxicity. CONCLUSIONS: Mild hepatotoxicity developed frequently after infusion of SIR-Spheres using the body surface area method, with normalization of LFTs in most patients. Grade 3 or greater toxicities were seen in < 10% of infusions. Toxicity was strongly associated with previous IA therapy.

Radioembolization as salvage therapy for hepatic metastasis of uveal melanoma: a single-institution experience.

OBJECTIVE: The purpose of this study was to assess the safety and efficacy of radioembolization in the management of hepatic metastasis of uveal melanoma after failure of immunoembolization or chemoembolization. MATERIALS AND METHODS: From January 2007 through April 2009, 32 patients underwent radioembolization therapy for hepatic metastasis of uveal melanoma. Pretreatment tumor burdens were divided into three categories: less than 25% (n = 25), 25-50% (n = 5), and greater than 50% (n = 2). Toxicity, extrahepatic disease, and hepatic tumor response were assessed 1 month and then every 3 months after treatment. Best radiographic response of hepatic metastasis was determined with the Response Evaluation Criteria in Solid Tumors criteria. Overall survival and progression-free survival of hepatic metastasis were estimated by Kaplan-Meier analysis. Differences in survival between subgroups were evaluated by log-rank test in univariate analysis. RESULTS: The clinical follow-up period ranged from 1.0 to 29.0 months (median, 10.0 months). The median overall survival was 10.0 months, and the progression-free survival of hepatic metastasis, 4.7 months. Twenty-two patients died 1.0-29.0 months (median, 5.8 months) after treatment owing to progression of liver disease (n = 13), extrahepatic disease (n = 4), or both (n = 5). Patients who had a pretreatment tumor burden less than 25% had longer median overall survival (10.5 vs 3.9 months, p = 0.0003) and progression-free survival (6.4 vs 3.0 months, p = 0.03) than patients who had a pretreatment tumor burden of 25% or greater. Patients who had a complete response (n = 1), partial response (n = 1), or stable disease (n = 18) had longer median overall survival (14.7 vs 4.9 months, p = 0.0006) and progression-free survival of hepatic metastasis (7.9 vs 3.1 months, p < 0.0001) than patients with tumor progression (n = 12). Self-limiting grade 1-2 systemic toxicity included tiredness (n = 9), indigestion (n = 2), and abdominal discomfort (n = 5). Grade 3-4 hepatic toxicity was attributed to tumor progression. CONCLUSION: Radioembolization is safe and effective salvage therapy for limited metastasis of uveal melanoma.

Side-branch embolization before 90Y radioembolization: rate of recanalization and new collateral development.

OBJECTIVE: The purpose of this study was to assess the rate of recanalization and collateral vessel formation after side-branch embolization during mapping angiography for planned (90)Y radioembolization. MATERIALS AND METHODS: Patients who underwent side-branch embolization at mapping angiography before (90)Y administration were included. Embolized vessels included the gastroduodenal artery, right gastric artery, and accessory arteries. Four interventional radiologists reviewed follow-up angiograms to assess recanalization and new collateral formation of embolized vessels. The time to recanalization or new collateral formation was tracked within 60 days and after the final arteriographic study. Differences in outcome among patients who had and those who had not undergone previous arterial directed therapy were reviewed. RESULTS: Fifty-six patients underwent side-branch embolization and follow-up arteriography; 124 treatments were performed after side-branch embolization (median, 2; range, 1-7), and the median follow-up period was 134 days (range, 7-684 days). Recanalization or new collateral vessel formation was found in 6 of 56 patients (10.7%) and in 8 of 56 patients (14.3%) 60 days after treatment or at final angiography, respectively. Embolization of 110 arteries was accomplished (42 gastroduodenal arteries, 46 right gastric arteries, and 22 accessory arteries). Two of 110 arteries (1.8%) recanalized, and four of 110 (3.6%) had new collateral vessels within 60 days. At final evaluation, 2 of 110 arteries (1.8%) had recanalized and 7 of 110 (6.4%) had new collaterals. Previous liver-directed therapy did not affect outcome (p > 0.05). No patient had symptomatic gastrointestinal ulceration. CONCLUSION: In more than 89% of patients, side-branch embolization provides durable occlusion for (90)Y radioembolization without collateral development or recanalization for a bilobar cycle of therapy. Further recanalization and collateral development at longer-term follow-up are minimal.

Sustainment of proactive physical therapy for individuals with early-stage Parkinson's disease: a quality improvement study over 4 years.

BACKGROUND: Implementation science frameworks aided the development of a new, evidence-based clinical physical therapy program. The purpose of this report is to describe the process of sustaining a clinical program in practice for over 4 years. We present a framework for integrating tools for sustainability with the Knowledge-to-Action model in the context of a proactive physical therapy (PAPT) program for individuals with early-stage Parkinson's disease. METHODS: Sustainability of implementation strategies was addressed using the Dynamic Sustainability Framework and sustainability assessment tools. Repeated retrospective medical record reviews and phone interviews were used to evaluate the reach and adoption of the PAPT over 4 years. Characteristics of those who engaged with PAPT, implementation fidelity, and clinical effectiveness were assessed for year 1 and year 3. Sustainability was measured using RE-AIM, NHS Sustainability Model, and Clinical Sustainability Assessment Tool. RESULTS: Reach increased from 28 to 110 total patients per year and spread occurred from one to three sites. PAPT user age, sex, Hoehn and Yahr rating, time since diagnosis, and type of insurance were similar in year 1 and year 3 (p > 0.05). The program sustained its effect to help participants increase or maintain self-reported exercise (Y1, 95%; Y3, 100%). However, upon evaluation PAPT users in year 3 had longer time since symptom onset and worse UPDRS motor scores compared to the PAPT users in year 1 (p < 0.05). All sites sustained the core intervention components, with sustainability scores of 71/100 (± 9.9) on the NHS Sustainability Model and 6.1/7 (± 0.9) on the Clinical Sustainability Assessment Tool. CONCLUSIONS: Integrating multiple sustainability models and assessments supported continued effectiveness, spread, and sustainment of PAPT for 4 years. Effective planning, anticipating common healthcare changes, and addressing sustainability determinants early in program implementation were essential aspects of long-term success.

Dosimetric Comparisons of Simulation Techniques for Left-Sided Breast Cancer in the COVID-19 Era: Techniques to Reduce Viral Transmission and Respect the Therapeutic Ratio.

Background The COVID-19 pandemic challenges our ability to safely treat breast cancer patients and requires revisiting current techniques to evaluate optimal strategies. Potential long-term sequelae of breast radiation have been addressed by deep inspiration breath-hold (DIBH), prone positioning, and four-dimensional computed tomography (4DCT) average intensity projection (AveIP)-based planning techniques. Dosimetric comparisons to determine the optimal technique to minimize the normal tissue dose for left-sided breast cancers have not been performed. Methods Ten patients with left-sided, early-stage breast cancer undergoing whole breast radiation were simulated in the prone position, supine with DIBH, and with a free-breathing 4DCT scan. The target and organs at risk (OAR) contours were delineated in all scans. Target volume coverage and OAR doses were assessed. One-way analysis of variance (ANOVA) and Kruskal-Wallis one-way ANOVA were used to detect differences in dosimetric parameters among the different treatment plans. Significance was set as p < 0.05. Results We demonstrate differences in heart and lung dose by the simulation technique. The mean heart doses in the prone, DIBH, and AveIP plans were 129 cGy, 154 cGy, and 262 cGy, respectively (p=0.02). The lung V20 in the prone, DIBH, and AveIP groups was 0.5%, 10.3% and 9.5%, respectively (p <0.001). Regardless of technique, lumpectomy planning target volume (PTV) coverage did not differ between the three plans with 95% of the lumpectomy PTV volume covered by 100.4% in prone plans, 98.5% in AveIP plans, and 99.3% in DIBH plans (p=0.7). Conclusions Prone positioning provides dosimetric advantages as compared to DIBH. When infection risks are considered as in the current coronavirus disease 2019 (COVID-19) pandemic, prone plans have advantages in reducing the risk of disease transmission. In instances where prone positioning is not feasible, obtaining an AveIP simulation may be useful in more accurately assessing heart and lung toxicity and informing a risk/benefit discussion of DIBH vs free breath-hold techniques.

A phase IB clinical trial of 15 Gy HDR brachytherapy followed by hypofractionated/SBRT in the management of intermediate-risk prostate cancer.

PURPOSE: High dose-rate (HDR) brachytherapy is commonly administered as a boost to external beam radiation therapy (EBRT). Our purpose was to compare toxicity with increasingly hypofractionated EBRT in combination with a single 15 Gy HDR boost for men with intermediate-risk prostate cancer. METHODS AND MATERIALS: Forty-two men were enrolled on this phase IB clinical trial to one of three EBRT dose cohorts: 10 fractions, seven fractions, or five fractions. Patients were followed prospectively for safety, efficacy, and health-related quality of life (Expanded Prostate Index Composite). Efficacy was assessed biochemically using the Phoenix definition. RESULTS: With a median follow up of 36 months, the biochemical disease-free survival was 95.5%. One man developed metastatic disease at 5 years. There was no significant minimally important difference in EPIC PRO for either urinary, bowel, or sexual domains. There was one acute Grade 3 GI and GU toxicity, but no late Grade 3 GU or GI toxicities. CONCLUSION: Fifteen gray HDR brachytherapy followed by a five fraction SBRT approach results in high disease control rates and low toxicity similar to previously reported HDR protocols with significant improvement in patient convenience and resource savings. While mature results with longer follow up are awaited, this treatment approach may be considered a safe and effective option for men with intermediate-risk disease.

Targeting the myeloid checkpoint receptor SIRPα potentiates innate and adaptive immune responses to promote anti-tumor activity.

BACKGROUND: Signal regulatory protein α (SIRPα) is a myeloid-lineage inhibitory receptor that restricts innate immunity through engagement of its cell surface ligand CD47. Blockade of the CD47-SIRPα interaction synergizes with tumor-specific antibodies and T-cell checkpoint inhibitors by promoting myeloid-mediated antitumor functions leading to the induction of adaptive immunity. Inhibition of the CD47-SIRPα interaction has focused predominantly on targeting CD47, which is expressed ubiquitously and contributes to the accelerated blood clearance of anti-CD47 therapeutics. Targeting SIRPα, which is myeloid-restricted, may provide a differential pharmacokinetic, safety, and efficacy profile; however, SIRPα polymorphisms and lack of pan-allelic and species cross-reactive agents have limited the clinical translation of antibodies against SIRPα. Here, we report the development of humanized AB21 (hAB21), a pan-allelic anti-SIRPα antibody that binds human, cynomolgus monkey, and mouse SIRPα alleles with high affinity and blocks the interaction with CD47. METHODS: Human macrophages derived from donors with various SIRPα v1 and v2 allelic status were used to assess the ability of hAB21 to enhance phagocytosis. HAB21_IgG subclasses were evaluated for targeted depletion of peripheral blood mononuclear cells, phagocytosis and in vivo efficacy in xenograft models. Combination therapy with anti-PD1/anti-PD-L1 in several syngeneic models was performed. Immunophenotyping of tissues from MC38 tumor-bearing mice treated with AB21 and anti-PD-1 was evaluated. PK, PD and tolerability of hAB21 were evaluated in cynomolgus monkeys. RESULTS: SIRPα blockade with hAB21 promoted macrophage-mediated antibody-dependent phagocytosis of tumor cells in vitro and improved responses to rituximab in the Raji human tumor xenograft mouse model. Combined with PD-1/PD-L1 blockade, AB21 improved response rates by facilitating monocyte activation, dendritic cell activation, and T cell effector functions resulting in long term, durable antitumor immunity. In cynomolgus monkeys, hAB21 has a half-life of 5.3 days at 10 mg/kg and complete target occupancy with no hematological toxicity or adverse findings at doses up to 30 mg/kg. CONCLUSIONS: The in vitro and in vivo antitumor activity of hAB21 broadly recapitulates that of CD47 targeted therapies despite differences in ligand expression, binding partners, and function, validating the CD47-SIRPα axis as a fundamental myeloid checkpoint pathway and its blockade as promising therapeutic intervention for treatment of human malignancies.

Overview of Extracellular Vesicles, Their Origin, Composition, Purpose, and Methods for Exosome Isolation and Analysis.

The use of extracellular vesicles, specifically exosomes, as carriers of biomarkers in extracellular spaces has been well demonstrated. Despite their promising potential, the use of exosomes in the clinical setting is restricted due to the lack of standardization in exosome isolation and analysis methods. The purpose of this review is to not only introduce the different types of extracellular vesicles but also to summarize their differences and similarities, and discuss different methods of exosome isolation and analysis currently used. A thorough understanding of the isolation and analysis methods currently being used could lead to some standardization in the field of exosomal research, allowing the use of exosomes in the clinical setting to become a reality.