Meaningful Dose Research Articles

Towards clinically relevant dose ratios for Cabamiquine and Pyronaridine combination using P. falciparum field isolate data

The selection and combination of dose regimens for antimalarials involve complex considerations including pharmacokinetic and pharmacodynamic interactions. In this study, we use immediate ex vivo P. falciparum field isolates to evaluate the effect of cabamiquine and pyronaridine as standalone treatments and in combination therapy. We feed the data into a pharmacometrics model to generate an interaction map and simulate meaningful clinical dose ratios. We demonstrate that the pharmacometrics model of parasite growth and killing provides a detailed description of parasite kinetics against cabamiquine-susceptible and resistant parasites. Pyronaridine monotherapy provides suboptimal killing rates at doses as high as 720 mg. In contrast, the combination of a single dose of 330 mg cabamiquine and 360 mg pyronaridine provides over 90% parasite killing in most of the simulated patients. The described methodology that combines a rapid, 3R-compliant in vitro method and modelling to set meaningful doses for new antimalarials could contribute to clinical drug development.

Hippocampal-Sparing Radiation Therapy in Primary Sinonasal and Cutaneous Tumors of the Head and Neck

Patients with primary sinonasal and cutaneous head and neck (H&N) malignancies often receive meaningful radiation dose to their hippocampi, but this not a classic avoidance structure in radiation planning. We aimed to characterize the feasibility and tradeoffs of hippocampal-sparing radiation therapy (HSRT) for patients with primary sinonasal and cutaneous H&N malignancies. We retrospectively selected patients who were treated definitively for primary sinonasal or cutaneous malignancies of the H&N at an academic medical center. All received (chemo)radiation alone or adjuvantly and substantial radiation dose to 1 or both hippocampi. We created new HSRT plans for each patient with intensity modulated radiation therapy using the original target and organ-at-risk (OAR) volumes. Hippocampi were contoured based on Radiation Therapy Oncology Group guidelines and reviewed by a neuroradiologist. Absolute and relative differences in radiation dose to the hippocampi, planning target volumes (PTVs), and OARs were recorded and compared. There were 18 sinonasal and 12 cutaneous H&N primary tumors (30 patients in total). Median prescription dose was 6600 cGy (range, 5000-7440 cGy), and 14 of the 30 patients received 120 cGy/fraction twice daily, 13 of the 30 patients received 200 cGy/fraction once daily, whereas others received 180-275 cGy/fraction once daily. The relative decrease in ipsilateral hippocampal Dmax and D100% using HSRT was 44% (median, 2009 cGy from 3586 cGy) and 65% (median 434 cGy from 1257 cGy), respectively. There were no statistically significant or clinically meaningful differences in PTV V100%, PTV D1%, or radiation dose to other OARs between HSRT and non-HSRT plans. HSRT is feasible and results in meaningful dose reduction to the hippocampi without reducing PTV coverage or increasing dose to other OARs. We suggest target hippocampal constraints of Dmax < 1600 cGy and D100% < 500 cGy when feasible (without compromising PTV coverage or impacting other critical OARs). The clinical significance of HSRT in patients with primary H&N tumors should be investigated prospectively.

Hippocampal-Sparing Radiotherapy in Primary Sinonasal and Cutaneous Head and Neck Malignancies: A Feasibility Study

Patients with primary sinonasal and cutaneous head and neck (H&N) malignancies often receive meaningful hippocampal doses, but the hippocampus is not a classic avoidance structure in radiation planning of these primary sites. This series characterizes the feasibility and tradeoffs of hippocampal-sparing radiotherapy (HSRT) for patients with primary sinonasal and cutaneous H&N malignancies. We retrospectively identified patients at a single institution treated definitively for primary sinonasal or cutaneous malignancies of the H&N. Each patient received (chemo)radiation and all received clinically-significant radiation dose to one or both hippocampi. We created new HSRT plans for each patient with intensity-modulated radiotherapy using original target and organ-at-risk (OAR) volumes. Hippocampi were contoured based on Radiation Therapy Oncology Group guidelines. Absolute and relative differences in radiation dose to the hippocampi, planning target volumes (PTV), and OARs were recorded. We used paired-samples t-tests to compare hippocampal and PTV dosimetric measures with and without HSRT. Thirty-seven patients were included (22 sinonasal, 11 cutaneous H&N, and 4 parotid primary tumors). Median prescription dose was 6600cGy (range: 5000-7440cGy). The most common fractionation regimens were 200cGy/fraction daily (51%, 19/37 patients) and 120cGy/fraction twice daily (41%, 15/37 patients). There were significant decreases in hippocampal Dmax and D100% using HSRT without compromising PTV coverage (Table 1). HSRT resulted in a relative increase of mean lacrimal gland dose by an average of 3.8%, optic chiasm Dmax by 1.3%, and whole brain Dmax of 1.2%. However, other OAR doses were lower with HSRT, including parotid gland mean dose, lens Dmax, optic nerve Dmax, cochlea mean dose, brainstem Dmax, and whole brain mean dose. HSRT is feasible and results in meaningful radiation dose reduction to the hippocampi without reducing PTV coverage or increasing dose to other OARs. The hippocampi should be regularly included as avoidance structures when treating primary sinonasal and cutaneous H&N tumors with radiation. We suggest target hippocampal constraints of Dmax < 1600cGy and D100% < 500cGy when feasible (without compromising PTV coverage). The clinical significance of HSRT in patients with primary H&N tumors should be investigated prospectively.

Lesion Dosimetry for [177Lu]Lu-PSMA-617 Radiopharmaceutical Therapy Combined with Stereotactic Body Radiotherapy in Patients with Oligometastatic Castration-Sensitive Prostate Cancer.

A single-institution prospective pilot clinical trial was performed to demonstrate the feasibility of combining [177Lu]Lu-PSMA-617 radiopharmaceutical therapy (RPT) with stereotactic body radiotherapy (SBRT) for the treatment of oligometastatic castration-sensitive prostate cancer. Methods: Six patients with 9 prostate-specific membrane antigen (PSMA)-positive oligometastases received 2 cycles of [177Lu]Lu-PSMA-617 RPT followed by SBRT. After the first intravenous infusion of [177Lu]Lu-PSMA-617 (7.46 ± 0.15 GBq), patients underwent SPECT/CT at 3.2 ± 0.5, 23.9 ± 0.4, and 87.4 ± 12.0 h. Voxel-based dosimetry was performed with calibration factors (11.7 counts per second/MBq) and recovery coefficients derived from in-house phantom experiments. Lesions were segmented on baseline PSMA PET/CT (50% SUVmax). After a second cycle of [177Lu]Lu-PSMA-617 (44 ± 3 d; 7.50 ± 0.10 GBq) and an interim PSMA PET/CT scan, SBRT (27 Gy in 3 fractions) was delivered to all PSMA-avid oligometastatic sites, followed by post-PSMA PET/CT. RPT and SBRT voxelwise dose maps were scaled (α/β = 3 Gy; repair half-time, 1.5 h) to calculate the biologically effective dose (BED). Results: All patients completed the combination therapy without complications. No grade 3+ toxicities were noted. The median of the lesion SUVmax as measured on PSMA PET was 16.8 (interquartile range [IQR], 11.6) (baseline), 6.2 (IQR, 2.7) (interim), and 2.9 (IQR, 1.4) (post). PET-derived lesion volumes were 0.4-1.7 cm3 The median lesion-absorbed dose (AD) from the first cycle of [177Lu]Lu-PSMA-617 RPT (ADRPT) was 27.7 Gy (range, 8.3-58.2 Gy; corresponding to 3.7 Gy/GBq, range, 1.1-7.7 Gy/GBq), whereas the median lesion AD from SBRT was 28.1 Gy (range, 26.7-28.8 Gy). Spearman rank correlation, ρ, was 0.90 between the baseline lesion PET SUVmax and SPECT SUVmax (P = 0.005), 0.74 (P = 0.046) between the baseline PET SUVmax and the lesion ADRPT, and -0.81 (P = 0.022) between the lesion ADRPT and the percent change in PET SUVmax (baseline to interim). The median for the lesion BED from RPT and SBRT was 159 Gy (range, 124-219 Gy). ρ between the BED from RPT and SBRT and the percent change in PET SUVmax (baseline to post) was -0.88 (P = 0.007). Two cycles of [177Lu]Lu-PSMA-617 RPT contributed approximately 40% to the maximum BED from RPT and SBRT. Conclusion: Lesional dosimetry in patients with oligometastatic castration-sensitive prostate cancer undergoing [177Lu]Lu-PSMA-617 RPT followed by SBRT is feasible. Combined RPT and SBRT may provide an efficient method to maximize the delivery of meaningful doses to oligometastatic disease while addressing potential microscopic disease reservoirs and limiting the dose exposure to normal tissues.

Radiation Exposure and Frequency of Dental, Bitewing and Occlusal Radiographs in Children and Adolescents.

Dental radiographs are valuable diagnostic aids for oral healthcare, but exposure to ionizing radiation carries health risks, especially in children due to their high radio-sensitivity. Valid reference values for intraoral radiographs in children and adolescents are still missing. This study aimed to investigate the radiation dose values and underlying justifications of dental, bitewing and occlusal X-rays in children and adolescents. Data from routinely executed intraoral radiographs between 2002 and 2020 with conventional and digital tube-heads were extracted from the Radiology Information System. The effective exposure was calculated from technical parameters and statistical tests performed. A total number of 4455 intraoral (3128 dental, 903 bitewing and 424 occlusal) radiographs were investigated. For dental and bitewing radiographs, the dose area product (DAP) was 2.57 cGy × cm2 and the effective dose (ED) 0.77 µSv. For occlusal radiographs, the DAP was 7.43 cGy × cm2 and the ED 2.22 µSv. Overall, 70.2% of all intraoral radiographs were dental, 20.3% bitewing and 9.5% occlusal radiographs. The most frequent indication for intraoral radiographs was trauma (28.7%), followed by caries (22.7%) and apical diagnostics (22.7%). Moreover, 59.7% of all intraoral radiographs were taken in boys, especially for trauma (66.5%) and endodontics (67.2%) (p ≤ 0.00). Girls were significantly more frequently X-rayed for caries diagnostics than boys (28.1% vs. 19.1%, p ≤ 0.00). The average ED of 0.77 µSv for intraoral dental and bitewing radiographs in this study was within the range of other reported values. The technical parameters of the X-ray devices were found at the lowest recommended levels to best limit the radiation exposure and to assure acceptable diagnostic efficacy. Intraoral radiographs were performed predominantly for trauma, caries and apical diagnostics-reflecting general recommendations for the use of X-rays in children. For improved quality assurance and radiation protection, further studies are necessary to determine the meaningful dose reference level (DRL) for children.

Early Transcriptional Activity of Vtr-297 - Results from an Ongoing Phase I Clinical Trial

VTR-297 (Trichostatin A) is a pan-inhibitor of histone deacetylases types 1, 2, 4, 6, and 10. Histone deacetylase inhibitors (HDACi) are well-known small molecules that increase the acetylation of lysine residues by inhibiting the activity of histone deacetylase enzymes. These anticancer agents affect epigenetic and non-epigenetic transcriptional regulation and are already part of effective clinical practice and hematology regimens. As HDACi are known for their relatively wide transcriptional modulation, we have conducted a high throughput screen to elucidate early transcriptional effects related to exposure to Trichostatin A (TSA) on patient-derived, clinical time-series samples. NCT03838926 is an ongoing, open-label, dose-escalation, phase I clinical trial for subjects with relapsed or refractory hematologic malignancies. Enrolled patients were assigned to receive one currently tested dose (1.25 / 2.50 / 5.00 mg; IV infusion) in 28-day cycles, 3-times a week for three weeks with one week off (IV administration days 1,3,5,8,10,12,15,17 and 19) until disease progression, unacceptable toxicity, or withdrawal of consent. The primary endpoint was safety/tolerability and maximum tolerated dose (MTD) of VTR-297 (TSA). Currently, twelve patients enrolled in the study, including Multiple Myeloma (MM, n=5), Non-Hodgkin's Lymphoma (NHL, n=5), and Hodgkin's Lymphoma (HL, n=2) across the first three dose-escalation cohorts that completed (1.25 / 2.50 / 5.00mg). No significant drug-related toxicities were reported, and MTD was not reached (recruitment is currently ongoing in the fourth dose cohort of 10mg). As a part of the exploratory analysis of whole blood (PBMC), patient samples were collected on cycle1 day1 (C1D1; pre-infusion, 15min-post, 30min-post, 1h-post, 2h-post, and 6h-post infusion) to capture any transcriptional changes (RNAseq) related to VTR-297 treatment. In the current analysis, samples were collected and analyzed in respective batches (15min / 30min / 1h / 2h / 6h) and compared with combined baseline samples (pre-infusion). Using Deseq2 to ascertain transcriptionally affected genes (pval<0.05, up/down relative fold-change 1.5x), we detected 136 differentially expressed genes across at least one of the time point analyzed. Among the detected genes, we found novel and previously described genes related to the core pathophysiology of myeloid and lymphoid disease (e.g., iron metabolism, vascular metastasis, and tyrosine kinase activity). In conclusion, these preliminary signatures offer early biomarker information related to a specific transcriptional activity elicited by intravenously delivered VTR-297 in the clinical setting. In an ongoing clinical study, we will further monitor, validate, and expand on these findings. Further observations at higher, safe, and clinically meaningful doses will complement our current, early picture of VTR-297 activity and how it can be used to optimize TSA-based treatments.

Reduction in Total On-Table Time for Palliative Radiation Patients Using Pre-Treatment Field Validation

<h3>Purpose/Objective(s)</h3> Palliative radiation therapy is commonly used to help relieve pain, prevent pathologic fracture, and improve quality of life. Physicians often use conventional 2D or 3D conformal radiotherapy to treat these lesions with multi-field arrangements. These fields are traditionally verified with portal images obtained with the patient on the treatment table, to simultaneously evaluate block design accuracy and isocenter position. Unfortunately, this process can be time-consuming as each field needs to be independently and sequentially verified, which can negatively impact patients in pain on the treatment table. Therefore, minimizing total "on-table" time by streamlining the validation process can improve patient experience and quality of life during radiation therapy. Our research investigates an alternative validation process to reduce total on-table time and improve clinic efficiency by validating all fields with port films obtained prior to patient arrival, then verifying isocenter position against patient anatomy using cone beam CT (CBCT). An isodose-line (IDL) surrogate structure was utilized as needed for either block edge (e.g., 50% IDL) or clinically meaningful dose (e.g., 95% IDL) when deemed useful for verification of anatomy within the treatment field. <h3>Materials/Methods</h3> Data was gathered for 172 patients treated for palliation over nine years at a single institution within the VA system. From our record and verify system, "total table time" was acquired – defined as time from initial image procurement to completion of first treatment delivery. Data was analyzed based on patient setup method (PORTs vs. Pre-PORTs + CBCT) in addition to the treatment site. <h3>Results</h3> We found a significant 60% reduction in average on-table time when implementing the Pre-PORTs + CBCT validation method as compared to the traditional PORTs only method. <h3>Conclusion</h3> We report a practical process to verify field design and treatment iso-center while reducing total table time, an important goal especially in palliative cases to minimize pain and improve patient experience during radiation therapy. Additionally, this approach improves workflow and can potentially increase clinic throughput. While cone beam CTs for palliative patients are not always feasible in current reimbursement models, this technique can also improve patient safety and treatment accuracy by automating shifts and limiting table time for combative or altered patients, and thereby might ultimately provide added incentive for changing those models.

Lorentz electron ptychography for imaging magnetic textures beyond the diffraction limit.

Nanoscale spin textures, especially magnetic skyrmions, have attracted intense interest as candidate high-density and power-efficient information carriers for spintronic devices1,2. Facilitating a deeper understanding of sub-hundred-nanometre to atomic-scale spin textures requires more advanced magnetic imaging techniques3-5. Here we demonstrate a Lorentz electron ptychography method that can enable high-resolution, high-sensitivity magnetic field imaging for widely available electron microscopes. The resolution of Lorentz electron ptychography is not limited by the usual diffraction limit of lens optics, but instead is determined by the maximum scattering angle at which a statistically meaningful dose can still be recorded-this can be an improvement of up to 2-6 times depending on the allowable dose. Using FeGe as the model system, we realize a more accurate magnetic field measurement of skyrmions with an improved spatial resolution and sensitivity by also correcting the probe-damping effect from the imaging optics via Lorentz electron ptychography. This allows us to directly resolve subtle internal structures of magnetic skyrmions near the skyrmion cores, boundaries and dislocations in an FeGe single crystal. Our study establishes a quantitative, high-resolution magnetic microscopy technique that can reveal nanoscale spin textures, especially magnetization discontinuities and topological defects in nanomagnets6. The technique's high-dose efficiency should also make it well suited for the exploration of magnetic textures in electron radiation-sensitive materials such as organic or molecular magnets7.

A systematic review on chlorine tolerance among bacteria and standardization of their assessment protocol in wastewater.

Though chlorine is a cost-effective disinfectant for water and wastewaters, the bacteria surviving after chlorination pose serious public health and environmental problems. This review critically assesses the mechanism of chlorine disinfection as described by various researchers; factors affecting chlorination efficacy; and the re-growth potential of microbial contaminations in treated wastewater post chlorination to arrive at meaningful doses for ensuring health safety. Literature analysis shows procedural inconsistencies in the assessment of chlorine tolerant bacteria, making it extremely difficult to compare the tolerance characteristics of different reported tolerant bacteria. A comparison of logarithmic reduction after chlorination and the concentration-time values for prominent pathogens led to the generation of a standard protocol for the assessment of chlorine tolerance. The factors that need to be critically monitored include applied chlorine doses, contact time, determination of chlorine demands of the medium, and the consideration of bacterial counts immediately after chlorination and in post chlorinated samples (regrowth). The protocol devised here appropriately assesses the chlorine-tolerant bacteria and urges the scientific community to report the regrowth characteristics as well. This would increase the confidence in data interpretation that can provide a better understanding of chlorine tolerance in bacteria and aid in formulating strategies for effective chlorination.

A phase 1 dose-escalation study of GCC19 CART a novel coupled CAR therapy for subjects with metastatic colorectal cancer.

3582 Background: Chimeric antigen receptor (CAR) T-cell therapy has shown remarkable clinical efficacy in hematologic malignancies but limited success in solid tumors. GCC19CART, the first clinical candidate from the CoupledCAR solid tumor platform, is designed to overcome the limitations of conventional CAR T-cells in solid tumor malignancies by pairing solid tumor CAR T-cells with CD19 targeting CAR T-cells to amplify proliferation and activation of the solid tumor CAR T component. GCC19CART targets guanylate cyclase-C (GCC) which is expressed in the metastatic lesions of 70%-80% of subjects with colorectal cancers. A Phase 1 investigator-initiated clinical trial is underway in China for patients with relapsed or refractory metastatic colorectal cancer who have received at least 2 prior lines of therapy. Based on a data cutoff on December 13, 2021, 21 subjects have been enrolled in 2 dose escalation groups at 5 hospitals in China. Methods: Subjects are screened for GCC expression by immunohistochemistry. Eligible subjects undergo leukapheresis, a single dose of lymphodepleting chemotherapy (fludarabine 30mg/m2 and cyclophosphamide 300mg/m2) 3 days prior to infusion, and then administration of a single infusion of GCC19CART at one of two preassigned doses: 1x106 or 2x106 CAR T-cells/kg. Endpoints are safety and preliminary evidence of efficacy as determined by CT or PET/CT per RECIST 1.1 or PERCIST 1.0. All responses were confirmed by an independent third-party imaging contract research organization (CRO). Results: 13 subjects have been enrolled to dose level 1 (1x106 cells/kg) and 8 subjects have been enrolled to dose level 2 (2x106 cells/kg). The most common adverse events were cytokine release syndrome (CRS) in 21/21 subjects (Grade 1 19/21 (90.48%) or Grade 2 2/21 (9.52%)) and diarrhea in 21/21 subjects (Grade 1 6/21 (28.57%) Grade 2 5/21 (23.81%) Grade 3 9/21 (42.86%) or Grade 4 1/21 (4.76%)). Neurotoxicity was observed in 2/21 (9.52%) subjects at Grade 3 or 4 and resolved with corticosteroids. The combined overall response rate (ORR) for both dose levels was 28.6% (6/21). For dose level 1, the overall response rate (ORR) per RECIST 1.1 was 15.4% (2/13). Two subjects demonstrated a partial response (PR) while 3 additional subjects had partial metabolic response (PMR) on PET/CT with stable disease (SD) or progressive disease (PD) per RECIST 1.1. For dose level 2, The ORR per RECIST 1.1 was 50% (4/8). 4 subjects demonstrated a PR (3 at month 1, 1 at month 3 after being SD at month 1) and 2 additional subjects had PMR on PET/CT with SD per RECIST 1.1. Conclusions: GCC19CART demonstrated meaningful dose dependent clinical activity and an acceptable safety profile in relapsed or refractory metastatic colorectal cancer. This trial is ongoing and updated data will be presented. A United States based Phase 1 trial of GCC19CART is anticipated for mid-2022. Clinical trial information: ChiCTR2100053828.

Translation of liver stage activity of M5717, a Plasmodium elongation factor 2 inhibitor: from bench to bedside

BackgroundTargeting the asymptomatic liver stage of Plasmodium infection through chemoprevention could become a key intervention to reduce malaria-associated incidence and mortality.MethodsM5717, a Plasmodium elongation factor 2 inhibitor, was assessed in vitro and in vivo with readily accessible Plasmodium berghei parasites. In an animal refinement, reduction, replacement approach, the in vitro IC99 value was used to feed a Population Pharmacokinetics modelling and simulation approach to determine meaningful effective doses for a subsequent Plasmodium sporozoite-induced volunteer infection study.ResultsDoses of 100 and 200 mg would provide exposures exceeding IC99 in 96 and 100% of the simulated population, respectively.ConclusionsThis approach has the potential to accelerate the search for new anti-malarials, to reduce the number of healthy volunteers needed in a clinical study and decrease and refine the animal use in the preclinical phase.Graphical

Nutraceuticals/Drugs Promoting Mitophagy and Mitochondrial Biogenesis May Combat the Mitochondrial Dysfunction Driving Progression of Dry Age-Related Macular Degeneration.

In patients with age-related macular degeneration (AMD), the crucial retinal pigment epithelial (RPE) cells are characterized by mitochondria that are structurally and functionally defective. Moreover, deficient expression of the mRNA-editing enzyme Dicer is noted specifically in these cells. This Dicer deficit up-regulates expression of Alu RNA, which in turn damages mitochondria—inducing the loss of membrane potential, boosting oxidant generation, and causing mitochondrial DNA to translocate to the cytoplasmic region. The cytoplasmic mtDNA, in conjunction with induced oxidative stress, triggers a non-canonical pathway of NLRP3 inflammasome activation, leading to the production of interleukin-18 that acts in an autocrine manner to induce apoptotic death of RPE cells, thereby driving progression of dry AMD. It is proposed that measures which jointly up-regulate mitophagy and mitochondrial biogenesis (MB), by replacing damaged mitochondria with “healthy” new ones, may lessen the adverse impact of Alu RNA on RPE cells, enabling the prevention or control of dry AMD. An analysis of the molecular biology underlying mitophagy/MB and inflammasome activation suggests that nutraceuticals or drugs that can activate Sirt1, AMPK, Nrf2, and PPARα may be useful in this regard. These include ferulic acid, melatonin urolithin A and glucosamine (Sirt1), metformin and berberine (AMPK), lipoic acid and broccoli sprout extract (Nrf2), and fibrate drugs and astaxanthin (PPARα). Hence, nutraceutical regimens providing physiologically meaningful doses of several or all of the: ferulic acid, melatonin, glucosamine, berberine, lipoic acid, and astaxanthin, may have potential for control of dry AMD.

Targeting Sirt1, AMPK, Nrf2, CK2, and Soluble Guanylate Cyclase with Nutraceuticals: A Practical Strategy for Preserving Bone Mass.

There is a vast pre-clinical literature suggesting that certain nutraceuticals have the potential to aid the preservation of bone mass in the context of estrogen withdrawal, glucocorticoid treatment, chronic inflammation, or aging. In an effort to bring some logical clarity to these findings, the signaling pathways regulating osteoblast, osteocyte, and osteoclast induction, activity, and survival are briefly reviewed in the present study. The focus is placed on the following factors: the mechanisms that induce and activate the RUNX2 transcription factor, a key driver of osteoblast differentiation and function; the promotion of autophagy and prevention of apoptosis in osteoblasts/osteoclasts; and the induction and activation of NFATc1, which promotes the expression of many proteins required for osteoclast-mediated osteolysis. This analysis suggests that the activation of sirtuin 1 (Sirt1), AMP-activated protein kinase (AMPK), the Nrf2 transcription factor, and soluble guanylate cyclase (sGC) can be expected to aid the maintenance of bone mass, whereas the inhibition of the serine kinase CK2 should also be protective in this regard. Fortuitously, nutraceuticals are available to address each of these targets. Sirt1 activation can be promoted with ferulic acid, N1-methylnicotinamide, melatonin, nicotinamide riboside, glucosamine, and thymoquinone. Berberine, such as the drug metformin, is a clinically useful activator of AMPK. Many agents, including lipoic acid, melatonin, thymoquinone, astaxanthin, and crucifera-derived sulforaphane, can promote Nrf2 activity. Pharmacological doses of biotin can directly stimulate sGC. Additionally, certain flavonols, notably quercetin, can inhibit CK2 in high nanomolar concentrations that may be clinically relevant. Many, though not all, of these agents have shown favorable effects on bone density and structure in rodent models of bone loss. Complex nutraceutical regimens providing a selection of these nutraceuticals in clinically meaningful doses may have an important potential for preserving bone health. Concurrent supplementation with taurine, N-acetylcysteine, vitamins D and K2, and minerals, including magnesium, zinc, and manganese, plus a diet naturally high in potassium, may also be helpful in this regard.

Adjustment of multi-leaf collimator parameters in 4-MV and 6-MV IMRT: A study of veterinary clinical cases.

Background:For optimal treatment, it is important to maintain optimal multi-leaf collimator (MLC) transmission in intensity-modulated radiation therapy (IMRT). However, adjustment of transmissions has not been reported in veterinary medicine.Aim:To demonstrate that appropriate MLC parameter adjustment for IMRT using 4- and 6-MV energy can reduce the need for quality assurance revalidation in real companion animal clinical cases.Methods:The MLC parameters (leaf transmission and leaf offset) of the treatment planning system were adjusted by evaluating seven plans (10 × 10 cm, 3ABUT, DMLC, 7segA, FOURL, HDMLC, and HIMRT) and 20 preclinical cases (10 cases each in 4- and 6-MV groups). Subsequently, 101 IMRT plans of 88 cases (77 dogs and 11 cats) were evaluated for absolute dose of plan target volume (PTV) and organs at risk (OAR) and were analyzed for the relative dose distribution by gamma analysis (3%/3 mm, >10%) using EBT3 film.Results:After adjustment of the MLC parameters (leaf transmission and leaf offset, 4 MV: 0.008 and 0, 6 MV: 0.005 and 0, respectively), the data from 101 plans (4 MV: 64 plans and 6 MV: 37 plans) treated with IMRT showed PTV <3%, OAR <5%, and gamma analysis pass rates ≥95% in all cases.Conclusion:Clinically meaningful dose distributions can be created even with a limited validation device if the treatment parameters are adjusted appropriately, even for tumors in canines and felines, where the irradiation field is small, the target is adjacent to the OAR, and the target is often superficial.

Proton Beam Therapy for Locally Advanced Head and Neck Tumors: An Analysis of Dosimetric and Clinical Outcomes.

Locally advanced tumors of the head and neck region often lie in close proximity to critical organs at risk (OARs). Providing effective treatment coverage to these malignancies while minimizing radiation dose to surrounding OARs is advantageous. Our aim is to compare dosimetric data of OARs from proton beam therapy (PBT) plans to volumetric modulated arc therapy (VMAT) treatment plans, and to evaluate clinical outcomes in patients treated with PBT. We identified patients with locally advanced head and neck tumors treated with PBT at our institution from 2016 to 2019. Study endpoints included mean and maximum doses for the OAR structures for each treatment plan, overall survival, time to local-regional or distant progression, and presence of acute and late toxicities. Mean and maximum doses to OAR structures were compared between treatment modalities using a paired Wilcoxon signed-rank test. P-values <0.05 were considered significant. A total of 42 patients were identified. Clinical target volume coverage was >95% for both PBT and VMAT plans. PBT plans showed a significant reduction to the mean doses to all OARs, and max doses to most OARs (P<0.05). The largest reduction mean dose was seen in the contralateral cochlea and parotid glands at 71% and 75%, respectively. Median follow-up was 27 months. Overall survival at 4 years was 44.75%. Freedom from local-regional progression was 73.28% at 2 years. The majority of patients developed Common Terminology Criteria for Adverse Events (CTCAE) grade I dermatitis, mucositis, or both. PBT resulted in meaningful dose reductions to OARs while maintaining comparable target coverage when compared with VMAT plans. Further refinements to proton therapy may have the potential to further minimize dose to critical structures.

Half: A Prospective Multi-Centre Phase II Clinical Trial Evaluating the Efficacy and Safety of Tyrosine Kinase Inhibitors' Discontinuation after Two-Step Dose Reduction in Patients with Chronic Myeloid Leukemia in Deep Molecular Remission

Background.Treatment-free remission (TFR) has become a new treatment goal for chronic myeloid leukemia (CML) patients. However, usually abrupt tyrosine kinase inhibitors (TKIs) therapy discontinuation has been successful only in about half of eligible patients and it can cause burdening TKI withdrawal syndrome (TWS) in about 30% of them. Moreover, any robust clinical or biological factor predictive for successful TFR has not been identified yet. On top of that, sustainable deep molecular response (DMR) as the main prerequisite for TKI discontinuation attempt is achieved only in 20-40% of patients. The majority of CML patients, therefore, need to be treated with the effective and well-tolerated drug for a long time or even life-long.Study design and methods.With the recognition of all these aspects, we designed a nationwide prospective investigator-initiated phase II clinical trial HALF (ClinicalTrials.gov NCT04147533) in order to evaluate efficacy and safety of TKI discontinuation after previous two-step dose reduction in patients with CML in DMR (Fig. 1). Step-wise TKI dose reduction, i.e. half of the standard during the first 6 months after study entry, and the same dose given alternatively (every other day) during the next 6 months, was derived from pharmacokinetics and experimental data as well as from clinical trials' results. We assume that the step-wise and eventually meaningful TKI dose reduction enables a higher rate of patients achieving successful TFR with less pronounce TWS, or even would represent a more reasonable and safer alternative to the complete and sudden TKI interruption. This unique nationwide academic project has been facilitated by hematological patients care centralization in the Czech Republic.A primary study objective is to evaluate the proportion of patients in major molecular response (MMR) at 6 and 12 months and in TFR at 18, 24, and 36 months after the study enrollment, respectively, and molecular recurrence-free survival at all mentioned time points as well. Main secondary and exploratory objectives are: to evaluate the proportion of patients loosing MMR and in whom MMR and MR4.0 would be re-achieved after TKI re-introduction, time to MMR and MR4.0 re-achievement, FFS, PFS, OS, TWS, and QoL assessment, predictive factors for successful TFR identification, quantification of BCR-ABL1 using digital droplet PCR at both the DNA and mRNA levels, immunological profiling, BCR-ABL1 kinetics mathematical modeling, assessment of TKI pharmacokinetics, clonal hematopoiesis and pharmaco-economics.Results.The study was launched in December 2019; however, due to the COVID-19 outbreak, patients' recruitment started on June 16, 2020. Here, characteristics of the first 74 patients included in the study until April 2021 are presented. There were 37 males and 37 females, with median age at the time of diagnosis of 53 years (range, 23-74) and at the time of the study entry of 67 years (range, 35-86). A median time of CML disease, TKI treatment, and DMR duration before the study initiation was as follows: 9.9 years (range, 4.4-22.5), 9.8 years (range, 4.2-20.2), and 7.3 years (range, 3.2-18.3), respectively. The ELTS score was low, intermediate, high and unknown in 62.2%, 21.6%, 13.5%, and 2.7% of patients, respectively. At the time of study entry, 58 patients (79.5%) were treated with imatinib, 10 (13.7%) with nilotinib, and 5 (6.8%) with dasatinib, respectively, whereas in 63 patients (86.3%) it was in the first line of therapy. With almost half of patients (48.6%), the TKI dose was already reduced at the time of study entry. With 10 (13.5%) patients, interferon-α treatment preceded TKI administration. At the time of this abstract preparation, on July 26, 2021, altogether 102 patients (from planned 150) have been enrolled in the study; 48 of them (47.1%) have already moved to the second de-escalation phase and 9 (8.8%) patients to the TFR phase. There were 2 cases of confirmed MMR loss (both in month 8 after the study entry) and no patient experienced symptoms resembling TWS.Conclusions.Despite the COVID-19 pandemic, the HALF study was successfully launched and initiated in the majority of centers, with 102 already included patients and continuing intensive enrolment. Based on our very preliminary results, the step-wise dose reduction seems to be an effective and safe approach. More included patients, longer follow-up and further analyses are needed in order to reach all set up objectives. [Display omitted] DisclosuresŽácková: Angelini: Consultancy, Speakers Bureau; Novartis: Speakers Bureau. Faber: Angelini: Consultancy, Other: conference fees, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Other: conference fees, Research Funding, Speakers Bureau; Novartis: Consultancy, Other: conference fees, Research Funding, Speakers Bureau; Pfizer: Other: conference fees; TERUMO: Other: conference fees. Bělohlávková: Novartis: Consultancy; BMS/Celgene: Consultancy. Horňák: Angelini: Honoraria. Svobodník: Roche: Speakers Bureau; Janssen-Cilag: Speakers Bureau. Machová Poláková: Incyte: Consultancy; Angelini: Consultancy; Novartis: Research Funding. Mayer: Principia: Research Funding.

PD21-10 SAFETY AND TOLERABILITY OF AN OXALATE-CONSUMING SYNTHETIC BIOTIC MEDICINE: SYNB8802 IN HEALTHY VOLUNTEERS WITH INDUCED DIETARY HYPEROXALURIA

You have accessJournal of UrologyStone Disease: Medical & Dietary Therapy (PD21)1 Sep 2021PD21-10 SAFETY AND TOLERABILITY OF AN OXALATE-CONSUMING SYNTHETIC BIOTIC MEDICINE: SYNB8802 IN HEALTHY VOLUNTEERS WITH INDUCED DIETARY HYPEROXALURIA Marja Puurunen, William Denney, Shawn Searle, Sushama Scalera, Andrew Marsh, David Lubkowicz, Caroline Kurtz, Aoife Brennan, and Richard Riese Marja PuurunenMarja Puurunen More articles by this author , William DenneyWilliam Denney More articles by this author , Shawn SearleShawn Searle More articles by this author , Sushama ScaleraSushama Scalera More articles by this author , Andrew MarshAndrew Marsh More articles by this author , David LubkowiczDavid Lubkowicz More articles by this author , Caroline KurtzCaroline Kurtz More articles by this author , Aoife BrennanAoife Brennan More articles by this author , and Richard RieseRichard Riese More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002010.10AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: High urinary oxalate levels (UOx) in patients with enteric hyperoxaluria (EH) can lead to recurrent kidney stones, nephrocalcinosis and chronic kidney disease (CKD). There are currently no approved pharmacological therapies for treating hyperoxaluria. SYNB8802 was developed by engineering a pathway for oxalate degradation in a probiotic strain of Escherichia coli Nissle 1917. SYNB8802 is an orally administered, non-systemically absorbed, non-colonizing live biotherapeutic developed for the treatment of EH. SYNB8802 acts in the gastrointestinal (GI) tract to convert oxalate to formate and CO2, two naturally occurring GI metabolites, to reduce urinary oxalate in patients with EH. METHODS: Adult healthy volunteers (HV) were enrolled in a multiple ascending dose study. Subjects started a high oxalate, low calcium diet run-in 4 days prior to first dose of the investigational product. They were then randomized (6 active:3 placebo) to receive 5 days of SYNB8802 or placebo TID, with the option of a 2-day dose-ramp period. 24hr UOx levels were measured daily. The primary outcome was safety and tolerability of SYNB8802. Secondary outcome was microbial kinetics of SYNB8802 in feces by qPCR. Exploratory outcomes assessed the effect of SYNB8802 on 24hr UOx excretion, UOx:U-creatinine ratio, and U-supersaturation biomarkers. RESULTS: Total of 45 HV were enrolled in 5 dose cohorts of 9 subjects each. There were no treatment-related serious adverse events or systemic toxicity. Adverse events were mainly classified as mild or moderate and mostly GI-related. Nausea and vomiting were dose-limiting at higher doses. Implementation of a 2-day dose-ramp limited adverse events. The maximum tolerated dose was 3x1011 live cells. There were no signs of colonization and all subjects cleared the bacteria after the last dose. Baseline UOx levels were increased to induce temporary dietary hyperoxaluria. A >20% decrease in 24hr UOx excretion was observed in SYNB8802 treated subjects compared with placebo at a well-tolerated dose. CONCLUSIONS: These results provide proof of mechanism for UOx lowering by the Synthetic Biotic medicine SYNB8802 through consumption of oxalate within the GI tract. SYNB8802 was well-tolerated at a potentially clinically meaningful dose. Further clinical development as a potential novel treatment for EH is warranted. Source of Funding: Synlogic Inc © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e378-e378 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Marja Puurunen More articles by this author William Denney More articles by this author Shawn Searle More articles by this author Sushama Scalera More articles by this author Andrew Marsh More articles by this author David Lubkowicz More articles by this author Caroline Kurtz More articles by this author Aoife Brennan More articles by this author Richard Riese More articles by this author Expand All Advertisement Loading ...

Cord Blood Regulatory T Cells for Prevention of Graft Versus Host Disease

Background: Regulatory T-cells (Tregs) are a T-cell subset capable of suppressing effector T-cells (Teffs) and, when given at the time of allogeneic hematopoietic stem cell transplantation (Allo-SCT), have been shown to prevent graft v. host disease (GVHD). We previously demonstrated that cord blood (CB) Tregs can be ex vivo expanded to clinically meaningful doses and prevent GVHD in a xenogenic mouse model. The efficacy of the ex vivo expanded CB Tregs in preventing GVHD was markedly improved with fucosylation, which adds fucose resulting in creation of a siayl-Lewis X moiety found on P-selectin ligand, thereby facilitating trafficking through the endothelium into inflammatory sites. We hypothesized that adoptive therapy with fucosylated Tregs could prevent GVHD even when given at suboptimal Tregs:Teffs ratios. We conducted a Phase I clinical trial to evaluate the clinical safety of fucosylated CB Treg infusion for GVHD prophylaxis (ww.clinicaltrials.gov NCT02423915). We now report on 5 patients who received GVHD prophylaxis with 3rdparty, ex-vivo expanded CB Tregs at a dose level of 1.0 x10e6 cells/ kg (2 un-fucosylated and 3 fucosylated CB Treg products).Patients and methods: A 3rd party CB unit with at least 3/6 HLA matching to the recipient was selected. Treg isolation and expansion was performed as shown previously. When indicated, expanded CB Tregs were incubated with substrate (GDP β-fucose) and fucosyltrasferase-VI (FT6) enzyme (TZ101, Targazyme, Carlsbad, CA) for 30 minutes, washed and infused on day -1. The first 2 patients underwent double cord transplant with Flu/Cy/TBI reduced intensity conditioning and received unfucosylated CB Tregs at a dose of 1 x 10e6/kg. The subsequent 3 patients underwent peripheral blood (PB) matched unrelated donor (MUD) transplant with Fludarabine/ Melphalan myeloablative conditioining and received fucosylated CB Tregs at a dose of 1 x 10e6/kg. All patients received additional pharmacologic GVHD prophylaxis with sirolimus and mycophenolate mofetil. All patients received their designated CB Treg dose. The median proportion of CD4+25+CD127- in the infused Treg product was 96% (94-98%). Expanded CB Treg product showed suppression of T cell proliferation using CFSE assay. For the first 2 patients, the infused graft Teffs dose was at least 12 times more than the CB Tregs and for the subsequent 3 patients, the dose of infused Teffs dose was at least 132 times more than that of the infused fucosylated CB Tregs. No infusion toxicities were observed.Results: All patients receiving fucosylated CB Tregs followed by PB MUD transplants exhibited non-infectious high fevers up to 40οC accompanied by an erythematous rash starting on post-transplant day +5 that lasted for 5-7 days and resolved after steroid administration (IV methylprednisolone 1mg/kg) for 24-96 hours. Skin biopsies were consistent with engraftment syndrome and not GVHD. All 5 patients engrafted at a median of 13 days. The three patients who received fucosylated CB Tregs and one of two patients receiving untreated CB Tregs developed ≥ grade II acute GVHD at a median of day +22 which had completely resolved by day 130 post-transplant. One patient had late onset aGVHD. No cGVHD was documented in any patient. One recipient of non-fucosylated Tregs died on day +40 due to unrelated causes (intracranial bleeding). No GVHD was observed in this patient. PB Flow cytometric analysis revealed an increase in inflammatory T-cell subsets in the first week post-transplant with a concurrent bimodal increase in the Treg populations on day -1 and day +7 (figure 1A). NK and DC but not B cell subsets were significantly increased. A consistent increase in the cell populations secreting IFNү, IL-4 and IL-17 was observed in the post-transplant period and a bi-modal increase in the IL-10 secreting cells was observed on Day -1 and Day +7 consistent with the circulating Treg cells (figure 1B).Conclusions: Our group is the first to show safety of infusing 3rd party, ex-vivo expanded CB Tregs in a PB MUD transplant setting. At a dose level of 1.0 x 10e6 /kg, 3rd party CB Tregs were administered without acute infusional toxicity and no negative impact on engraftment. The cause for the high fevers observed in the fucosylated CB Treg recipients is unclear at this time. We are now enrolling additional patients with unfucosylated Tregs in a PB MUD transplant setting to investigate the mechanisms underlying this phenomenon. [Display omitted] DisclosuresKhoury:Kiromics: Research Funding; Angle: Research Funding; Stemline Therapeutics: Research Funding; Pfizer: Research Funding.

High spatial resolution dosimetry with uncertainty analysis using Raman micro-spectroscopy readout of radiochromic films.

The purpose of this work is to develop a new approach for high spatial resolution dosimetry based on Raman micro-spectroscopy scanning of radiochromic film (RCF). The goal is to generate dose calibration curves over an extended dose range from 0 to 50Gy and with improved sensitivity to low (<2Gy) doses, in addition to evaluating the uncertainties in dose estimation associated with the calibration curves. Samples of RCF (EBT3) were irradiated at a broad dose range of 0.03-50Gy using an Elekta Synergy clinical linear accelerator. Raman spectra were acquired with a custom-built Raman micro-spectroscopy setup involving a 500 mW, multimode 785 nm laser focused to a lateral spot diameter of 30µm on the RCF. The depth of focus of 34µm enabled the concurrent collection of Raman spectra from the RCF active layer and the polyester laminate. The preprocessed Raman spectra were normalized to the intensity of the 1614cm-1 Raman peak from the polyester laminate that was unaltered by radiation. The mean intensities and the corresponding standard deviation of the active layer Raman peaks at 696, 1445, and 2060cm-1 were determined for the 150×100µm2 scan area per dose value. This was used to generate three calibration curves that enabled the conversion of the measured Raman intensity to dose values. The experimental, fitting, and total dose uncertainty was determined across the entire dose range for the dosimetry system of Raman micro-spectroscopy and RCF. In contrast to previous work that investigated the Raman response of RCFs using different methods, high resolution in the dose response of the RCF, even down to 0.03Gy, was obtained in this study. The dynamic range of the calibration curves based on all three Raman peaks in the RCF extended up to 50Gy with no saturation. At a spatial resolution of 30×30µm2 , the total uncertainty in estimating dose in the 0.5-50Gy dose range was [6-9]% for all three Raman calibration curves. This consisted of the experimental uncertainty of [5-8]%, and the fitting uncertainty of [2.5-4.5]%. The main contribution to the experimental uncertainty was determined to be from the scan area inhomogeneity which can be readily reduced in future experiments. The fitting uncertainty could be reduced by performing Raman measurements on RCF samples at further intermediate dose values in the high and low dose range. The high spatial resolution experimental dosimetry technique based on Raman micro-spectroscopy and RCF presented here, could become potentially useful for applications in microdosimetry to produce meaningful dose estimates in cellular targets, as well as for applications based on small field dosimetry that involve high dose gradients.

Adeno-associated Virus (AAV) Capsid Chimeras with Enhanced Infectivity Reveal a Core Element in the AAV Genome Critical for both Cell Transduction and Capsid Assembly.

Adeno-associated viruses (AAV) have attracted significant attention in the field of gene and cell therapy due to highly effective delivery of therapeutic genes into human cells. The ability to generate recombinant AAV vectors compromised of unique or substituted protein sequences has led to the development of capsid variants with improved therapeutic properties. Seeking novel AAV vectors capable of enhanced transduction for therapeutic applications, we have developed a series of unique capsid variants termed AAV X-Vivo (AAV-XV) derived from chimeras of AAV12 VP1/2 sequences and the VP3 sequence of AAV6. These AAV variants showed enhanced infection of human primary T cells, hematopoietic stem cells, and neuronal cell lines over wildtype parental viruses, and superiority over AAV6 for genomic integration of DNA sequences by AAV alone or in combination with CRISPR gene editing. AAV-XV variants demonstrate transduction efficiency equivalent to AAV6 at multiplicities of infection 2 logs lower, enabling T cell engineering at low AAV doses. The protein coding sequence of these novel AAV chimeras revealed disruptions within the assembly-activating protein (AAP) which likely accounted for observed lower virus yield. A series of genome alterations, reverting the AAP sequence back to wildtype AAV6, had a negative impact on the enhanced transduction seen with AAV-VX, indicating overlapping functions within this sequence for both viral assembly and effective T cell transduction. Our findings show these AAV-XV variants are highly efficient at cell transduction at low dose and demonstrates the importance of the AAP coding region in both viral particle assembly and cell infection.IMPORTANCE A major hurdle to the therapeutic potential of AAV in gene therapy lies in achieving clinically meaningful AAV doses, and secondarily, ability to manufacture commercially viable titers of AAV to support this. By virtue of neutralizing antibodies against AAV that impede patient repeat-dosing, the dose of AAV for in vivo gene delivery has been high, which has resulted in unfortunate recent safety concerns and deaths in patients given higher-dose AAV gene therapy. We have generated new AAV variants possessing unique combinations of capsid proteins for gene and cell therapy applications termed AAV-XV, which have high levels of cell transduction and gene delivery at lower MOI. Furthermore, we demonstrate a novel finding, and an important consideration for recombinant AAV design, that a region of the AAV genome encoding the capsid viral protein and AAP is critical for both virus yield and the enhancement of infection/transduction.