On this page we list publications obtained with the support of the BCMFF.

CLINICAL STUDIES

University of Pennsylvania – Dr. Samuel G Jacobson

Blue cone monochromacy (BCM) is an X-linked inherited retinal degeneration (IRD)

caused by mutations in the OPN1LW/OPN1MW gene cluster, encoding long (L)- and

middle (M)-wavelength sensitive (i.e. red-green) cone opsins. The visual disabilities of BCM patients are serious and include reduced visual acuity, and abnormal color vision.

Progress in understanding BCM relevant to therapy has occurred  thanks to Dr. SG Jacobson in the Center for Hereditary Retinal Degenerations at Scheie Eye Institute from 2010 to 2023 . The following peer-reviewed publications illustrate this progress and are briefly summarized below.

1) 2013: Evidence to warrant gene therapy in BCM (Cideciyan et al.:

Cideciyan AV, Hufnagel RB, Carroll J, Sumaroka A, Luo X, Schwartz SB, Dubra A, Land M, Michaelides M, Gardner JC, Hardcastle AJ, Moore AT, Sisk RA, Ahmed ZM, Kohl S, Wissinger B, Jacobson SG. Human cone visual pigment deletions spare sufficient photoreceptors to warrant gene therapy. Hum Gene Ther. 2013; 24: 993-1006.

https://pubmed.ncbi.nlm.nih.gov/24067079/

Our original set of observations in a cohort of BCM patients tested the hypothesis that a gene therapy strategy was warranted in this condition. We concluded through non-invasive measures of foveal-retinal structure in BCM patients over a wide age range that human cones could survive, albeit in reduced numbers, and there was an anatomical substrate for gene augmentation.

2) 2015: Clinically-feasible outcomes for a BCM trial (Luo et al.)

Luo X, Cideciyan AV, Iannaccone A, Roman AJ, Ditta LC, Jennings BJ, Yatsenko SA,

Sheplock R, Sumaroka A, Swider M, Schwartz SB, Wissinger B, Kohl S, Jacobson SG.

Blue cone monochromacy: visual function and efficacy outcome measures for clinical

trials. PLoS One. 2015; 10: e0125700.

https://pubmed.ncbi.nlm.nih.gov/25909963/

The next step forward that we took was to ask what efficacy outcome measures would be clinically feasible for a BCM clinical trial. Among the outcomes evaluated in BCM patients were kinetic and automated chromatic perimetry, full-field stimuli on chromatic backgrounds, and eye movement and fixation monitoring with retinal imaging. Of importance to interpretation of outcomes, foveal sensitivity, unlike in normal subjects, was not mediated by long-/middle-wavelength (L-/M-) cones but by rod vision. Fixation location could vary from foveal to parafoveal. It was concluded that BCM rods continued to signal vision under conditions normally associated with daylight vision.

3) 2016: Modified microperimetry as a BCM outcome (Cideciyan et al.):

Cideciyan AV, Roman AJ, Jacobson SG, Yan B, Pascolini M, Charng J, Pajaro S,

Nirenberg S. Developing an outcome measure with high luminance for optogenetics

treatment of severe retinal degenerations and for gene therapy of cone diseases. Invest Ophthalmol Vis Sci. 2016; 57: 3211-21.

https://pubmed.ncbi.nlm.nih.gov/27309625/

Understanding how BCM patients use their vision led to the development of a modified microperimeter that allowed for presenting varied stimuli with a wide range of luminance and chromaticity while precisely monitoring retinal features of regions were being tested.

4) 2018: Different BCM genotypes lead to different phenotypes (Sumaroka et al.):

Sumaroka A, Garafalo AV, Cideciyan AV, Charng J, Roman AJ, Choi W, Saxena S,

Aksianiuk V, Kohl S, Wissinger B, Jacobson SG. Blue cone monochromacy caused by

the C203R missense mutation or large deletion mutations. Invest Ophthalmol Vis Sci.

2018 Dec 3;59(15):5762-72.

https://pubmed.ncbi.nlm.nih.gov/30516820/

More recent work has helped to lay the groundwork for a clinical trial to treat BCM. We performed a natural history study of BCM patients to understand the effect of genotype on disease presentation and progression. Recognizing that there are two common genotype categories causing BCM, we asked if there was any measurable difference in the phenotypes caused by large deletion (covering the locus control region and/or parts or the entire gene cluster) versus missense mutations (specifically, C203R). Other authors had raised concern that a C203R mutation could involve misfolded cone opsins with a potential for a toxic effect on the photoreceptors, such as had been found with certain missense mutations in rhodopsin. Without any concensus in the literature about the severity of the BCM phenotype in patients with the C203R mutation, we examined the foveal cone layer across an age spectrum in the two genotypes. The surprising result was that disease progression in BCM due to C203R mutation was less aggressive than in the BCM patients with deletion mutations. There was a prolonged period of foveal ONL retention in C203R patients – about 3 decades of life (about ages 20-50 years). After this observation, we called in further patients with the different genotypes at later ages to test the hypothesis and the result was confirmed. Intuitively, it may have been expected that these retinal structural measurements may not have been needed to prove the point; simple visual acuity may have provided the same answer. Yet, here was no comparable pattern of acuity progression based on the different genotypes – acuity was reduced throughout the disease course. The results provided much useful information on how to organize a clinical trial and make decisions about inclusion/exclusion criteria.

5) 2020: Predicting BCM efficacy after therapy using artificial intelligence (Sumaroka et al.):

Sumaroka A, Cideciyan AV, Sheplock R, Wu V, Kohl S, Wissinger B, Jacobson SG.

Foveal therapy in blue cone monochromacy: predictions of visual potential from artificial intelligence. Front Neurosci. 2020 Aug 3;14:800.

https://pubmed.ncbi.nlm.nih.gov/32848570/

A key question was then asked of the BCM foveal data: Would supervised machine

learning allow prediction of post-treatment foveal function in BCM patients, based on

their foveal cone structure? A machine learning technique was used to associate foveal sensitivities and best corrected visual acuities to foveal structure in a group of patients with non-BCM inherited retinal degenerations and a cohort of BCM patients. The two groups of patients had a comparable range of foveal structure. Machine learning was able to predict foveal sensitivity from segmented or unsegmented optical coherence tomography input. From these studies, we proposed that foveal vision improvement potential in BCM is predictable from retinal structure using machine learning and curve fitting approaches. This should allow estimates of maximum efficacy in patients being considered for clinical trials and also guide decisions about dosing.

6) 2020: Reading performance in BCM as a clinical trial outcome (Semenov et al.):

Semenov EP, Sheplock R, Roman AJ, McGuigan DB, Swider M, Cideciyan AV, Jacobson SG. Reading performance in blue cone monochromacy: defining an outcome measure for a clinical trial. Transl Vis Sci Technol. 2020 Dec 8;9(13):13.

https://pubmed.ncbi.nlm.nih.gov/33344057/

BCM patients experience difficulties with near vision as well as distance vision tasks. We asked whether there were definable abnormalities in reading vision performance in a cohort of BCM patients using an iPad application of MNREAD, a well-studied method originally developed three decades ago. MNREAD curves in BCM of print size versus reading speed were all right-shifted compared with normal. All parameters in BCM patients indicated abnormal reading performance. Intersession variability, although slightly higher in BCM than in normal subjects, was comparable with results previously reported for other patients with maculopathy. There was a high degree of disease symmetry in reading performance parameters in the BCM cohort studied. Of further relevance, reverse polarity showed better reading parameters than regular polarity in ~80% of BCM patients. The MNREAD measures of reading performance would be both a worthy and robust secondary outcome in a clinical trial protocol and would sever the dual purpose of quantifying macular vision and addressing a key quality of life issue.

7) 2021-2022: Color vision in BCM: choosing the clinical trial outcome measures

Mascio AA, Roman AJ, Cideciyan AV, Sheplock R, Wu V, Garafalo AV, Sumaroka A,

Pirkle S, Kohl S, Wissinger B, Jacobson SG and Barbur JL. Color vision in blue cone

monochromacy: outcome measures for a clinical trial. ransl Vis Sci Technol. 2023 Jan 3;12(1):25. doi: 10.1167/tvst.12.1.25. PMID: 36692456; PMCID: PMC9896867.

https://pubmed.ncbi.nlm.nih.gov/36692456/

We have studied color vision test methods in BCM in anticipation of IND submission for the clinical trial. A cohort of BCM patients and subjects with normal vision were examined with two different types of color tests: Farnsworth-Munsell (FM) cap arrangement tests (FM D15 and Roth28) and the webbased Colour Assessment and Diagnosis (CAD) test. Parameters derived from the measurements in patients were compared to normal data and also within the group of patients. Inter-session, inter-ocular and between-subject variabilities were determined. The FM testing seeks to determine if there are different patterns of results within the cohort of BCM patients tested. The CAD test can measure RG (red/green) and YB (yellow/blue) chromatic sensitivity using dynamic luminance contrast noise to isolate the use of color signals. RG and YB color thresholds and the severity of any loss have been measured in clinical studies of AMD, diabetes, aniridia, mild hypoxia, and in a trial of diabetic macular edema treated with intravitreal steroid implants. 

University of Pennsylvania – Dr. Artur V Cideciyan and Dr. Tomas Aleman

8) 2024: Evaluation of Retinal Structure and Visual Function in Blue Cone Monochromacy to Develop Clinical Endpoints for L-opsin Gene Therapy.

UCL Institute of Ophthalmology, University College London, London, United Kingdom – Dr. Michael  Michaelides, Dr. Emily J Patterson

University of Tübingen, Germany – Dr. Bernd Wissinger and Susanne Kohl

11) De novo intrachromosomal gene conversion from OPN1MW to OPN1LW in the male germline results in Blue Cone Monochromacy. 2016

Buena-Atienza, E., Rüther, K., Baumann, B. et al. De novo intrachromosomal gene conversion from OPN1MW to OPN1LW in the male germline results in Blue Cone Monochromacy. Sci Rep 6, 28253 (2016). https://doi.org/10.1038/srep28253

https://www.nature.com/articles/srep28253

Here we investigated 24 affected males frm 16 families with either a structurally intact gene cluster or at least one intact single (hybrid) gene but harbouring rare combinations of common SNPs in exon 3 in single or multiple OPN1LW and OPN1MW gene copies. We assessed twelve different OPN1LW/MW exon 3 haplotypes by semi-quantitative minigene splicing assay. Nine haplotypes resulted in aberrant splicing of ≥20% of transcripts including the known pathogenic haplotypes (i.e. ‘LIAVA’, ‘LVAVA’) with absent or minute amounts of correctly spliced transcripts, respectively. De novo formation of the ‘LIAVA’ haplotype derived from an ancestral less deleterious ‘LIAVS’ haplotype was observed in one family with strikingly different phenotypes among affected family members.

12) A 73,128 bp de novo deletion encompassing the OPN1LW/OPN1MW gene cluster in sporadic Blue Cone Monochromacy: a case report. (2018)

 Buena-Atienza E, Nasser F, Kohl S, Wissinger B. A 73,128 bp de novo deletion encompassing the OPN1LW/OPN1MW gene cluster in sporadic Blue Cone Monochromacy: a case report. BMC Med Genet. 2018 Jun 26;19(1):107. doi: 10.1186/s12881-018-0623-8. PMID: 29940872; PMCID: PMC6019650.

https://pubmed.ncbi.nlm.nih.gov/29940872/

We report a 24-year-old male presenting with congenital photophobia, nystagmus and colour vision abnormalities. There was no history of retinal dystrophy in the family. Clinical diagnosis of BCM was supported by genetic investigations of the patient and his family members. Molecular genetic analysis of the OPN1LW/OPN1MW gene cluster revealed a novel deletion of about 73 kb in the patient encompassing the LCR. The deletion was absent in the X-chromosomes of both the mother and transmitting grandfather.

13) Novel OPN1LW/OPN1MW Exon 3 Haplotype-Associated Splicing Defect in Patients with X-Linked Cone Dysfunction (2022)

Stingl, Katarina, Britta Baumann, Pietro De Angeli, Ajoy Vincent, Elise Héon, Monique Cordonnier, Elfriede De Baere, Salmo Raskin, Mario Teruo Sato, Naoye Shiokawa, and et al. 2022. “Novel OPN1LW/OPN1MW Exon 3 Haplotype-Associated Splicing Defect in Patients with X-Linked Cone Dysfunction” International Journal of Molecular Sciences 23, no. 12: 6868.

https://doi.org/10.3390/ijms23126868

14) The landscape of submicroscopic structural variants at the OPN1LW/OPN1MW gene cluster on Xq28 underlying blue cone monochromacy. 2022

Wissinger B, Baumann B, Buena-Atienza E, Ravesh Z, Cideciyan AV, Stingl K, Audo I, Meunier I, Bocquet B, Traboulsi EI, Hardcastle AJ, Gardner JC, Michaelides M, Branham KE, Rosenberg T, Andreasson S, Dollfus H, Birch D, Vincent AL, Martorell L, Català Mora J, Kellner U, Rüther K, Lorenz B, Preising MN, Manfredini E, Zarate YA, Vijzelaar R, Zrenner E, Jacobson SG, Kohl S. The landscape of submicroscopic structural variants at the OPN1LW/OPN1MW gene cluster on Xq28 underlying blue cone monochromacy. Proc Natl Acad Sci U S A. 2022 Jul 5;119(27):e2115538119. doi: 10.1073/pnas.2115538119. Epub 2022 Jun 27. PMID: 35759666; PMCID: PMC9271157.

https://pubmed.ncbi.nlm.nih.gov/35759666/

Here, we investigated the prevalence and the landscape of submicroscopic structural variants (SVs) at single-base resolution in BCM patients. We found that about one-third (n = 73) of the 213 molecularly confirmed BCM families carry an SV, most commonly deletions restricted to the OPN1LW/OPN1MW gene cluster. The structure and precise breakpoints of the SVs were resolved in all but one of the 73 families. Twenty-two families-all from the United States-showed the same SV, and we confirmed a common ancestry of this mutation. In total, 42 distinct SVs were identified, including 40 previously unreported SVs, thereby quadrupling the number of precisely mapped SVs underlying BCM. 

15) Pitfalls in the genetic testing of the OPN1LW-OPN1MW gene cluster in human subjects (2024)

Wissinger, B., Baumann, B., Buena-Atienza, E. et al. Pitfalls in the genetic testing of the OPN1LW-OPN1MW gene cluster in human subjects. npj Genom. Med. 9, 28 (2024).

https://doi.org/10.1038/s41525-024-00406-y

Ophthalmic Genetics Group, Institute of Molecular and Clinical Ophthalmology Basel (IOB) Switzerland – Mathieu Quinodoz and Carlo Rivolta 

16)

AAV VECTORS AND GENE THERAPIES

West Virginia University – Dr. WenTao  Deng

17) Blue cone monochromacy and gene therapy. (2023)

University of Florida – Dr. WW Hauswirth

18) Human L- and M-opsins restore M-cone function in a mouse model for human blue cone monochromacy. (2018)

Deng WT, Li J, Zhu P, Chiodo VA, Smith WC, Freedman B, Baehr W, Pang J, Hauswirth WW. Human L- and M-opsins restore M-cone function in a mouse model for human blue cone monochromacy. Mol Vis. 2018 Jan 8;24:17-28. PMID: 29386880; PMCID: PMC5757852/

https://pmc.ncbi.nlm.nih.gov/articles/PMC5757852/

In this study, we tested whether exogenously expressed human L- and M-opsins can rescue M-cone function in an M-opsin knockout (Opn1mw^−/−) mouse model for BCM.

19) Gene-based Therapy in a Mouse Model of Blue Cone Monochromacy.(2017)

Zhang Y, Deng WT, Du W, Zhu P, Li J, Xu F, Sun J, Gerstner CD, Baehr W, Boye SL, Zhao C, Hauswirth WW, Pang JJ. Gene-based Therapy in a Mouse Model of Blue Cone Monochromacy. Sci Rep. 2017 Jul 27;7(1):6690. doi: 10.1038/s41598-017-06982-7. Erratum in: Sci Rep. 2018 Mar 14;8(1):4807. doi: 10.1038/s41598-018-23131-w. PMID: 28751656; PMCID: PMC5532293.

https://pubmed.ncbi.nlm.nih.gov/28751656/

We generated an M-opsin knockout mouse (Opn1mw ^-/-) expressing only S-opsin as a model for human BCM. We show that recombinant M-opsin delivered by AAV5 vectors rescues M-cone function in Opn1mw ^-/- mice. We also show that AAV delivered M-opsin localizes in the dorsal cone outer segments, and co-localizes with S-opsin in the ventral retina. Our study demonstrates that cones without M-opsin remain viable and respond to gene augmentation therapy, thereby providing proof-of-concept for cone function restoration in BCM patients.

20) Successful rescue of M-cone function in aged M-opsin knock-out mice, a model for blue cone monochromacy (2019)

https://iovs.arvojournals.org/article.aspx?articleid=2743266

We show that the numbers of positive PNA-stained cells were only slightly reduced in dorsal retinas of aged Opn1mw^-/- mice, demonstrating that cone inner segments and cone sheaths remain intact and that the dorsal cones remain viable even in 16-month-old Opn1mw^-/- mice. Consistent with this observation, AAV5-mediated expression of human L-opsin rescues M-cone function (60 ± 8 µV in treated eyes vs unrecordable in untreated, n=8, P < 0.005), and restores OS morphology in dorsal retinas of Opn1mw^-/- mice treated at 12 months of age. We also show that M-cone function (45 ± 4 µV, n=8, P < 0.005) and structure rescue lasted for at least 12 months in Opn1mw^-/- mice treated at 7 months of age.

Dorsal cones of Opn1mw^-/- mice without visual pigments remain viable for at least 12 months and can still be functionally and structurally rescued by human cone opsin gene therapy. These results have important implications for BCM patient entry selection in any future BCM gene therapy clinical trial.

Adverum Biotechnologies

The BCM Families Foundation supported for many years the development of the ADVM-062 gene Therapy of Adverum Biotechnology:

21) Preclinical evaluation of ADVM-062, a novel intravitreal gene therapy vector for the treatment of blue cone monochromacy (2023)

Hanna K, Nieves J, Dowd C, Bender KO, Sharma P, Singh B, Renz M, Ver Hoeve JN, Cepeda D, Gelfman CM, Riley BE, Grishanin RN. Preclinical evaluation of ADVM-062, a novel intravitreal gene therapy vector for the treatment of blue cone monochromacy. Mol Ther. 2023 Jul 5;31(7):2014-2027. doi: 10.1016/j.ymthe.2023.03.011. Epub 2023 Mar 16. PMID: 36932675; PMCID: PMC10362383.

https://pmc.ncbi.nlm.nih.gov/articles/PMC10362383/#ack0010

Here we describe the use of ADVM-062, a vector optimized for cone-specific expression of human L-opsin and administered using a single intravitreal (IVT) injection. Pharmacological activity of ADVM-062 was established in gerbils, whose cone-rich retina naturally lacks L-opsin. A single IVT administration dose of ADVM-062 effectively transduced gerbil cone photoreceptors and produced a de novo response to long-wavelength stimuli. To identify potential first-in-human doses we evaluated ADVM-062 in non-human primates. Cone-specific expression of ADVM-062 in primates was confirmed using ADVM-062.myc, a vector engineered with the same regulatory elements as ADVM-062. Enumeration of human OPN1LW.myc-positive cones demonstrated that doses ≥3 × 10¹⁰ vg/eye resulted in transduction of 18%-85% of foveal cones. A Good Laboratory Practice (GLP) toxicology study established that IVT administration of ADVM-062 was well tolerated at doses that could potentially achieve clinically meaningful effect, thus supporting the potential of ADVM-062 as a one-time IVT gene therapy for BCM.