An ALK2 inhibitor, BLU-782, prevents heterotopic ossification in a mouse model of fibrodysplasia ossificans progressiva.

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disease driven by gain-of-function variants in activin receptor-like kinase 2 (ALK2), the most common variant being ALK2R206H. In FOP, ALK2 variants display increased and dysregulated signaling through the bone morphogenetic protein (BMP) pathway resulting in progressive and permanent replacement of skeletal muscle and connective tissues with heterotopic bone, ultimately leading to severe debilitation and premature death. Here, we describe the discovery of BLU-782 (IPN60130), a small-molecule ALK2R206H inhibitor developed for the treatment of FOP. A small-molecule library was screened in a biochemical ALK2 binding assay to identify potent ALK2 binding compounds. Iterative rounds of structure-guided drug design were used to optimize compounds for ALK2R206H binding, ALK2 selectivity, and other desirable pharmacokinetic properties. BLU-782 preferentially bound to ALK2R206H with high affinity, inhibiting signaling from ALK2R206H and other rare FOP variants in cells in vitro without affecting signaling of closely related homologs ALK1, ALK3, and ALK6. In vivo efficacy of BLU-782 was demonstrated using a conditional knock-in ALK2R206H mouse model, where prophylactic oral dosing reduced edema and prevented cartilage and heterotopic ossification (HO) in both muscle and bone injury models. BLU-782 treatment preserved the normal muscle-healing response in ALK2R206H mice. Delayed dosing revealed a short 2-day window after injury when BLU-782 treatment prevented HO in ALK2R206H mice, but dosing delays of 4 days or longer abrogated HO prevention. Together, these data suggest that BLU-782 may be a candidate for prevention of HO in FOP.

Sex as a Critical Variable in Basic and Pre-Clinical Studies of Fibrodysplasia Ossificans Progressiva.

Heterotopic ossification (HO) is most dramatically manifested in the rare and severely debilitating disease, fibrodysplasia ossificans progressiva (FOP), in which heterotopic bone progressively accumulates in skeletal muscles and associated soft tissues. The great majority of FOP cases are caused by a single amino acid substitution in the type 1 bone morphogenetic protein (BMP) receptor ACVR1, a mutation that imparts responsiveness to activin A. Although it is well-established that biological sex is a critical variable in a range of physiological and disease processes, the impact of sex on HO in animal models of FOP has not been explored. We show that female FOP mice exhibit both significantly greater and more variable HO responses after muscle injury. Additionally, the incidence of spontaneous HO was significantly greater in female mice. This sex dimorphism is not dependent on gonadally derived sex hormones, and reciprocal cell transplantations indicate that apparent differences in osteogenic activity are intrinsic to the sex of the transplanted cells. By circumventing the absolute requirement for activin A using an agonist of mutant ACVR1, we show that the female-specific response to muscle injury or BMP2 implantation is dependent on activin A. These data identify sex as a critical variable in basic and pre-clinical studies of FOP.

Slow Binocular Reading in Amblyopic Children Is a Fellow Eye Deficit.

SIGNIFICANCE: Amblyopic children read 25% slower than their peers during binocular silent reading. PURPOSE: We compared binocular reading to fellow eye reading to determine whether slow reading in amblyopic children is due to binocular inhibition; that is, the amblyopic eye is interfering during binocular reading. METHODS: In a cross-sectional study, 38 children with amblyopia and 36 age-similar control children who completed grades 1 to 6 were enrolled. Children silently read grade-appropriate paragraphs during binocular reading and fellow eye reading while wearing ReadAlyzer eye-tracking goggles (Compevo AB, Stockholm, Sweden). Reading rate, number of forward saccades, number of regressive saccades, and fixation duration were analyzed between groups and between viewing conditions. We also examined whether sensory factors (amblyopia severity, stereoacuity, suppression) were related to slow reading. RESULTS: For amblyopic children, binocular reading versus fellow eye reading did not differ for reading rate (176 ± 60 vs. 173 ± 53 words per minute, P = .69), number of forward saccades (104 ± 35 vs. 97 ± 33 saccades/100 words, P = .18), number of regressive saccades (21 ± 15 vs. 22 ± 13 saccades/100 words, P = .75), or fixation duration (0.31 ± 0.06 vs. 0.32 ± 0.07 seconds, P = .44). As expected, amblyopic children had a slower reading rate and more forward saccades than control children during binocular reading and fellow eye reading. Slow reading was not related to any sensory factors. CONCLUSIONS: Binocular reading did not differ from fellow eye reading in amblyopic children. Thus, binocular inhibition is unlikely to play a role in slow binocular reading and is instead a fellow eye deficit that emerges from a disruption in binocular visual experience during development.

An anti-ACVR1 antibody exacerbates heterotopic ossification by fibro-adipogenic progenitors in fibrodysplasia ossificans progressiva mice.

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disease characterized by progressive and catastrophic heterotopic ossification (HO) of skeletal muscle and associated soft tissues. FOP is caused by dominantly acting mutations in the gene encoding the bone morphogenetic protein (BMP) type I receptor, ACVR1 (ALK2), the most prevalent of which results in an arginine to histidine substitution at position 206 (ACVR1[R206H]). The fundamental pathological consequence of FOP-causing ACVR1 receptor mutations is to enable activin A to initiate canonical BMP signaling in fibro-adipogenic progenitors (FAPs), which drives HO. We developed a monoclonal blocking antibody (JAB0505) against the extracellular domain of ACVR1 and tested its effect on HO in 2 independent FOP mouse models. Although JAB0505 inhibited BMP-dependent gene expression in wild-type and ACVR1(R206H)-overexpressing cell lines, JAB0505 treatment profoundly exacerbated injury-induced HO. JAB0505-treated mice exhibited multiple, distinct foci of heterotopic lesions, suggesting an atypically broad anatomical domain of FAP recruitment to endochondral ossification. This was accompanied by dysregulated FAP population growth and an abnormally sustained immunological reaction following muscle injury. JAB0505 drove injury-induced HO in the absence of activin A, indicating that JAB0505 has receptor agonist activity. These data raise serious safety and efficacy concerns for the use of bivalent anti-ACVR1 antibodies to treat patients with FOP.

Randomized clinical trial of streaming dichoptic movies versus patching for treatment of amblyopia in children aged 3 to 7 years.

Contrast-rebalanced dichoptic movies have been shown to be an effective binocular treatment for amblyopia in the laboratory. Yet, at-home therapy is a more practical approach. In a randomized clinical trial, we compared dichoptic movies, streamed at-home on a handheld 3D-enabled game console, versus patching as amblyopia treatment. Sixty-five amblyopic children (3-7 years; 20/32-125) were randomly assigned to one of two parallel arms, binocular treatment (3 movies/week) or patching (14 h/week). The primary outcome, change in best corrected visual acuity (BCVA) at the 2-week visit was completed by 28 and 30, respectively. After the primary outcome, both groups of children had the option to complete up to 6 weeks of binocular treatment. At the 2-week primary outcome visit, BCVA had improved in the movie (0.07 ± 0.02 logMAR; p < .001) and patching (0.06 ± 0.01 logMAR; p < 0.001) groups. There was no significant difference between groups (CI95%: - 0.02 to 0.04; p = .48). Visual acuity improved in both groups with binocular treatment up to 6 weeks (0.15 and 0.18 logMAR improvement, respectively). This novel, at-home, binocular movie treatment improved amblyopic eye BCVA after 2 weeks (similar to patching), with additional improvement up to 6 weeks. Repeated binocular visual experience with contrast-rebalanced binocular movies provides an additional treatment option for amblyopia.Clincaltrials.gov identifier: NCT03825107 (31/01/2019).

Plasma-Soluble Biomarkers for Fibrodysplasia Ossificans Progressiva (FOP) Reflect Acute and Chronic Inflammatory States.

Fibrodysplasia ossificans progressiva (FOP) is a progressive, debilitating genetic disease in which skeletal muscle and connective tissue is episodically replaced by heterotopic bone. Discovery of surrogate biomarkers of disease (genotype)-related and flare-up-associated activity of FOP in a readily accessible matrix, such as plasma, would facilitate an understanding of the complex pathophysiology of FOP, aid patient care, and provide a valuable tool for the development and monitoring of potential therapeutics. In a case-control study, using a carefully collected and curated set of plasma samples from 40 FOP patients with the classic ACVR1R206H mutation and 40 age- and sex-matched controls, we report the identification of disease-related and flare-up-associated biomarkers of FOP using a multiplex analysis of 113 plasma-soluble analytes. Adiponectin (implicated in hypoxia, inflammation, and heterotopic ossification) as well as tenascin-C (an endogenous activator of innate immune signaling through the TLR4 pathway and a substrate for kallikrein-7) were highly correlated with FOP genotype, while kallikrein-7 was highly correlated with acute flare-up status. Plasma-soluble biomarkers for FOP support a flare-up-related acute inflammatory phase of disease activity superimposed on a genotypic background of chronic inflammation. © 2021 American Society for Bone and Mineral Research (ASBMR).

Differential CD4+ T-Cell Cytokine and Cytotoxic Responses Between Reactivation and Latent Phases of Herpes Zoster Infection.

Background: CD4+ T cells are a critical component of effective immune responses to varicella zoster virus (VZV), but their functional properties during the reactivation acute vs latent phase of infection remain poorly defined. Methods: Here we assessed the functional and transcriptomic properties of peripheral blood CD4+ T cells in persons with acute herpes zoster (HZ) compared to those with a prior history of HZ infection using multicolor flow cytometry and RNA sequencing. Results: We found significant differences between the polyfunctionality of VZV-specific total memory, effector memory, and central memory CD4+ T cells in acute vs prior HZ. VZV-specific CD4+ memory T-cell responses in acute HZ reactivation had higher frequencies of IFN-γ and IL-2 producing cells compared to those with prior HZ. In addition, cytotoxic markers were higher in VZV-specific CD4+ T cells than non-VZV-specific cells. Transcriptomic analysis of ex vivo total memory CD4+ T cells from these individuals showed differential regulation of T-cell survival and differentiation pathways, including TCR, cytotoxic T lymphocytes (CTL), T helper, inflammation, and MTOR signaling pathways. These gene signatures correlated with the frequency of IFN-γ and IL-2 producing cells responding to VZV. Conclusions: In summary, VZV-specific CD4+ T cells from acute HZ individuals had unique functional and transcriptomic features, and VZV-specific CD4+ T cells as a group had a higher expression of cytotoxic molecules including Perforin, Granzyme-B, and CD107a.

Reach Kinematics During Binocular Viewing in 7- to 12-Year-Old Children With Strabismus.

Purpose: Eye-hand coordination is essential for normal development and learning. Discordant binocular experience from childhood strabismus results in sensory and ocular motor impairments that can affect eye-hand coordination. We assessed reach kinematics during visually guided reaching in children treated for strabismus compared with controls. Methods: Thirty-six children aged 7 to 12 years diagnosed with esotropia, a form of strabismus, and a group of 35 age-similar control children were enrolled. Reach movements during visually guided reaching were recorded using the LEAP Motion Controller. While viewing binocularly, children reached out and touched a small dot that appeared randomly in one of four locations (±5° or ±10°). Kinematic measures were reach reaction time, total reach duration, peak velocity, acceleration duration, and deceleration duration. Touch accuracy and factors associated with impaired reach kinematics were evaluated. Results: Strabismic children had longer total reach duration (545 ± 60 ms vs. 504 ± 43 ms; P = 0.002), had longer deceleration duration (343 ± 54 ms vs. 312 ± 45 ms; P = 0.010), and were less accurate (93% ± 6% vs. 96% ± 5%, P = 0.007) than controls. No differences were found for reach reaction time, peak velocity, or acceleration duration (all Ps ≥ 0.197). Binocular dysfunction was more related to slow reaching than amblyopic eye visual acuity. Conclusions: Strabismus affects visually guided reaching in children, with slower reaching in the final approach and reduced endpoint accuracy. Binocular dysfunction was predictive of slow reaching. Unlike strabismic adults who show longer acceleration duration, longer deceleration in the final approach in strabismic children indicates a difference in control that could be due to reduced ability to use visual feedback.

Normative Values, Testability, and Validity for a New Preferential Looking Stereoacuity Test.

Introduction: Age norms and testability for 3-5 year old children have been reported for the PASS III stereotest using a pointing response. We aimed to expand the normative data to children as young as 6 months, assess testability, and evaluate validity use of the PASS III as a preferential-looking test for younger children and children with special needs. Methods: 68 control children, 362 children with eye conditions, and 167 children with special needs were tested with the PASS III. Percent testable was calculated for children with and without special needs, normal tolerance limits were determined, and test validity was assessed. Results: In controls, mean PASS III stereoacuity improved from 371 arcsec at 12 months to 174 arcsec at 24 months, and 87 arcsec at 36 months. Testability in the 12, 24, and 36 months age groups were 81%, 87%, and 97% respectively and 92% for special needs children. Comparison to previously published norms and testing in a known nil stereoacuity cohort supported PASS III test validity. Compared to gold standard stereoacuity tests, accuracy of the PASS was 89%. Conclusion: Overall, preferential-looking tests using the PASS III provide a sensitive and specific measure of stereoacuity with high testability for young children and children with special needs.

A randomized clinical trial of contrast increment protocols for binocular amblyopia treatment.

BACKGROUND: Most clinical trials of contrast-rebalanced binocular amblyopia treatment used a contrast increment protocol of 10% daily with successful play. Paired with a definition of success requiring only 15-30 min/day of gameplay, this increment protocol could allow children to reach 100% fellow eye contrast in 3-9 hours; however, this may not provide adequate therapeutic time with reduced fellow eye contrast. The purpose of this study was to compare the original protocol against three alternative contrast increment protocols designed to increase the number of treatment hours. METHODS: In this prospective study, 63 amblyopic children (4-10 years; amblyopic eye visual acuity, 20/40-125) were randomly assigned one of four daily contrast increment protocols for 4 weeks, all starting with 20% fellow eye contrast: 10%, 5%, 0%, or 10% for first 4 weeks then reset to 20% and repeat 10% increment for the final 4 weeks. Children played contrast-rebalanced games for 1 hour/day, 5 days/week. Best-corrected visual acuity, stereoacuity, and suppression were assessed at baseline and every 2 weeks until the 8-week outcome visit. RESULTS: At baseline, mean amblyopic eye best-corrected visual acuity was 0.47 ± 0.14 logMAR (20/60), improving overall 0.14 ± 0.08 logMAR (1.4 lines; P < 0.0001) at 8 weeks. All four protocols resulted in similar improvement in visual acuity (0.13-0.16 logMAR; all Ps < 0.0002). Stereoacuity and suppression also improved (all Ps < 0.05). CONCLUSIONS: None of the new protocols resulted in less improvement than the original 10% contrast increment protocol. Contrast-rebalanced binocular games yielded significant improvements in visual acuity, stereoacuity, and suppression with or without daily contrast increments.

Endoscopic removal of eroded laparoscopic adjustable gastric bands: a preferred approach.

BACKGROUND: Complications related to laparoscopic adjustable gastric banding (LAGB) have led to an increased number of removals. An uncommon but potentially devastating complication is gastric band erosion into the gastric lumen, which can be managed by open surgical, laparoscopic, and endoscopic approaches. OBJECTIVE: A wide array of management techniques has been reported for removal of LAGB that have eroded into the stomach. We describe the preferred method for successful endoscopic band removal at our institution. SETTING: Community tertiary-care referral hospital accredited by the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program. METHODS: A single-center, retrospective review of a prospectively maintained database was used to identify patients who underwent LAGB removal from 2009 to 2019. We identified the subset of patients with band erosion. We analyzed patient characteristics, presenting symptoms, diagnostic modalities, and method of band extraction. RESULTS: A total of 132 patients underwent LAGB removal, among whom 22 (16.7%) patients were diagnosed with erosion. Seven (32%) patients underwent laparoscopic removal, 14 (64%) patients underwent endoscopic removal, and 1 patient (4%) underwent combined laparoscopic and endoscopic approach. These latter patients had variable amounts of erosion and buckle visibility, but all underwent endoscopic retrieval. We found that using an endoscopic retrograde cholangiopancreatography guidewire with an endoscopic retrograde cholangiopancreatography mechanical lithotriptor for band transection and snare for retrieval have been effective. CONCLUSIONS: A standardized, multidisciplinary, and minimally invasive endoscopic approach for LAGB erosion has been found to be successful without the need for further surgical intervention and may be offered to patients upon discovery of erosion.

Activin-dependent signaling in fibro/adipogenic progenitors causes fibrodysplasia ossificans progressiva.

Fibrodysplasia ossificans progressiva (FOP) is a rare autosomal-dominant disorder characterized by progressive and profoundly disabling heterotopic ossification (HO). Here we show that fibro/adipogenic progenitors (FAPs) are a major cell-of-origin of HO in an accurate genetic mouse model of FOP (Acvr1 tnR206H ). Targeted expression of the disease-causing type I bone morphogenetic protein (BMP) receptor, ACVR1(R206H), to FAPs recapitulates the full spectrum of HO observed in FOP patients. ACVR1(R206H)-expressing FAPs, but not wild-type FAPs, activate osteogenic signaling in response to activin ligands. Conditional loss of the wild-type Acvr1 allele dramatically exacerbates FAP-directed HO, suggesting that mutant and wild-type ACVR1 receptor complexes compete for activin ligands or type II BMP receptor binding partners. Finally, systemic inhibition of activin A completely blocks HO and restores wild-type-like behavior to transplanted Acvr1 R206H/+ FAPs. Understanding the cells that drive HO may facilitate the development of cell-specific therapeutic approaches to inhibit catastrophic bone formation in FOP.

Positional ocular flutter and thickened optic nerves as sentinel signs of Krabbe disease.

A 5-month-old boy developed a large-amplitude, horizontal pendular flutterlike oscillation of the eyes, when placed in the supine position. Magnetic resonance imaging (MRI) 1 month earlier had shown isolated thickening of the optic nerves and chiasm without other central nervous system signal abnormalities. Repeat MRI at 5½ months of age showed a constellation of central nervous system signal abnormalities suggestive of Krabbe disease. The diagnosis was confirmed with serum enzymatic and genetic testing. This case demonstrates that positional ocular flutter can be a presenting sign of Krabbe disease and reinforces the observation that isolated thickening of the anterior visual pathways can antedate other central nervous system abnormalities on MRI.

A TPO receptor agonist, ALXN4100TPO, mitigates radiation-induced lethality and stimulates hematopoiesis in CD2F1 mice.

Thrombopoietin (TPO) receptor agonists lacking sequence homology to TPO were designed by grafting a known peptide sequence into the hinge and/or kappa constant regions of a human anti-anthrax antibody. Some of these proteins were equipotent to TPO in stimulating cMpl-r activity in vitro and in increasing platelet levels in vivo. ALXN4100TPO (4100TPO), the best agonist in this series with a K(d) of 30 nM for cMpl-r, exhibited potent activity as a radiation countermeasure in CD2F1 mice exposed to lethal total-body radiation from a cobalt-60 γ-ray source. 4100TPO (2 mg/kg, s.c.) administered once either 24 h before or 6 h after TBI showed superior protection to five daily doses given before or after TBI. Prophylactic administration (69 to 94% survival) was superior to therapeutic schedules (60% survival). 4100TPO conferred a significant survival benefit (P < 0.01) when administered 4 days before or even 12 h after exposure and across a dose range of 0.1 to 8 mg/kg. The dose reduction factors (DRFs) with a single dose of 1 mg/kg 4100TPO 24 h before or 12 h after TBI were 1.32 and 1.11, respectively (P < 0.0001). Furthermore, 4100TPO increased bone marrow cellularity and megakaryocytic development and accelerated multi-lineage hematopoietic recovery in irradiated mice, demonstrating the potential of 4100TPO as both a protector and a mitigator in the event of a radiological incident.

A comparison of rates of lymph node metastases between patients undergoing sentinel and axillary lymphadenectomy.

BACKGROUND: Recommendations regarding credentialing for sentinel lymphadenectomy in the staging of breast cancer emphasize the need for a trial period during which novice surgeons remove both the sentinel lymph node and the axillary packet, to demonstrate acceptably low rates of both operative failure and inaccuracy. METHODS: We initiated sentinel lymph node mapping in our institution without planned axillary dissection. To establish our ability to accurately stage patients using sentinel lymphadenectomy, we compared 225 patients who underwent that procedure and 343 patients previously staged with axillary lymph node dissection. RESULTS: No differences in node positivity were found between the two groups. Among sentinel lymphadenectomy patients, no differences were found between patients in the first and second half of the institutional experience. CONCLUSIONS: We question the need for a trial period of planned axillary node dissection with sentinel lymph node mapping, and review the evidence from other investigators regarding its necessity.

Long-term rates of PCO following small incision foldable acrylic intraocular lens implantation in children.

PURPOSE: To evaluate the long-term incidence of postoperative posterior capsular opacification (PCO) in children undergoing small incision foldable acrylic lens implantation with at least 2 years of follow up. METHODS: In 18 children, 26 eyes underwent small incision cataract extraction with posterior chamber foldable acrylic lens implantation. The posterior capsule was left intact in all patients at the time of surgery. RESULTS: With a mean follow up of 2.75 years and a mean age at surgery of 8.25 years, 13 of 26 eyes (50%) developed visually significant PCO requiring intervention. In the group of children under 4 years of age, 5 of 5 eyes (100%) developed visually significant PCO, while 8 of 21 eyes (38%) in the group of children over 4 years of age developed opacification. Four of 26 eyes (15%) required two procedures (either repeat Nd:YAG laser capsulotomy or pars plana secondary membrane removal) to clear the visual axis. CONCLUSION: In this study, the incidence of PCO following small incision acrylic lens implantation in children over 4 years of age is lower than those rates reported by conventional large incision rigid lens techniques with a minimum of 2 years follow up. This technique has advantages over conventional techniques in older children because it offers less surgical intervention, a lower cost to patients, and less risk of vitreous and retinal complications.