Sylentis, PharmaMar Group, initiates a Phase I clinical trial with SYL1801 for retinal diseases

  • This Phase I trial will enroll 36 healthy volunteers and will be conducted at the Hospital Universitario Ramón y Cajal in Madrid (Spain).
  • The safety of SYL1801 at different doses, as well as its pharmacokinetic profile, will be evaluated.
  • SYL1801 has been developed by Sylentis and is based on RNA interference (RNAi) technology.
  • The compound will be administered as eye drops for the treatment and/or prevention of retinal diseases, such as age-related macular degeneration or diabetic retinopathy.

Madrid (Spain), March 18th, 2021. – Sylentis, a wholly owned subsidiary of PharmaMar Group (MSE:PHM), has announced today the initiation of the first Phase I trial with its investigational compound SYL1801 for the treatment and/or prevention of choroidal neovascularization, a common cause of retinal diseases such as Age-related Macular Degeneration (AMD) and diabetic retinopathy.

This is a Phase I clinical trial involving 36 healthy volunteers and will be carried out at the Ramón y Cajal University Hospital in Madrid (Spain). This study will evaluate the safety of SYL1801 at different doses, along with the pharmacokinetic profile of the product.

SYL1801 is a compound based on RNA interference (RNAi), administered in the form of eye drops, which blocks the synthesis of the receptor NRARP (NOTCH Regulated Ankyrin Repeat Protein), involved in choroidal neovascularization (AMD pathology).

Currently, neovascular AMD is mostly treated with regular intravitreal injections of anti-VEGF agents, a very uncomfortable procedure for patients and also a huge investment of financial and time resources for healthcare systems[i]. SYL1801 represents a breakthrough in innovative drug development through RNAi-based gene silencing technology and, administered in the form of eye drops, could change the treatment paradigm for this disease.

It is estimated that the number of individuals with AMD will reach 288 million, worldwide, by 2040. AMD is the leading cause of irreversible visual impairment in the elderly population of developed countries, accounting for 8% of all cases of blindness around the world. In fact, the overall prevalence of AMD between 45 and 85 years of age is 8.7%[ii],[iii].

Ana Isabel Jiménez, COO and head of R&D at Sylentis, comments that “The compounds traditionally used to treat retinal diseases are antibodies, large molecules that cannot reach the retina from the ocular surface. This is why they are administered through intravitreal injections. Patients with age-related macular degeneration or diabetic retinopathy must periodically visit the hospital, where this type of procedure, which is often associated with a negative emotional impact and a large expenditure of time, is performed.

Sylentis is a leading research company in gene silencing technology using RNAi and is one of the few to apply this technology in the field of ophthalmology.

Explanatory video:

What is RNA interference?

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About PharmaMar

Headquartered in Madrid, PharmaMar is a biopharmaceutical company, focused on oncology and committed to research and development which takes its inspiration from the sea to discover molecules with antitumor activity. It is a company that seeks innovative products to provide healthcare professionals with new tools to treat cancer. Its commitment to patients and to research has made it one of the world leaders in the discovery of antitumor drugs of marine origin.

PharmaMar has a pipeline of drug candidates and a robust R&D oncology program. It develops and commercializes Yondelis® in Europe and has other clinical-stage programs under development for several types of solid cancers: Zepzelca® (lurbinectedin, PM1183), PM184 and PM14. With subsidiaries in Germany, Italy, France, Switzerland, Belgium, Austria and the United States. PharmaMar wholly owns other companies: GENOMICA, a molecular diagnostics company; Sylentis, dedicated to researching therapeutic applications of gene silencing (RNAi). To learn more about PharmaMar, please visit us at

About Sylentis

Sylentis is a pharmaceutical company that develops innovative therapies based on gene silencing technologies or RNAi. This technology enables the design of molecules capable of selectively inhibiting the synthesis of disease-causing proteins. Sylentis has developed numerous therapies based on this novel technology and currently has a strong program in ophthalmology with one candidate in Phase III clinical trials: tivanisiran, for the treatment of dry eye; and another in Phase II: bamosiran, for the treatment of glaucoma. Sylentis is also researching and developing other new products for the treatment of various eye diseases such as ocular allergies and retinal diseases. For more information, visit

About SYL1801

SYL1801 is an RNAi-based drug administered as eye drops that selectively inhibits NRARP receptor production. NRARP, by regulating the Notch and Wnt signaling pathways in endothelial cells, plays an important role in the control of choroidal neovascularization. SYL1801 is a synthetic small double-stranded RNA (siRNA) oligonucleotide that acts through a highly selective mechanism of action. Non-clinical studies conducted by Sylentis with SYL1801 have demonstrated high capacity to inhibit this target specifically. The reduction of its expression in the retina, observed in animal models, correlates with vessel regression and decreased retinal vascular growth following topical administration.

SYL1801 is a product under development to treat age-related macular degeneration, with potential for development for other pathologies involving choroidal neovascularization.

About RNA interference (RNAi)

RNA interference is a technology that seeks to reduce abnormal protein production by silencing messenger RNA. RNAi represents a breakthrough as a new mechanism of action to address numerous pathologies. Some pathologies, such as age-related macular degeneration, are caused by an alteration of certain proteins. This technology can act by reducing or controlling in a very specific way the production of the proteins involved in each pathology. Compounds based on RNAi technology tend to have a longer effect than traditional drugs and few side effects, due to their high specificity.


[i] Sivaprasad, S. and S. Oyetunde, Impact of injection therapy on retinal patients with diabetic macular edema or retinal vein occlusion. Clin Ophthalmol, 2016. 10: p. 939-46.

[ii] Deng, Y., et al., Therapeutic potentials of gene silencing by RNA interference: principles, challenges, and new strategies. Gene, 2014. 538(2): p. 217-27.

[iii] Jonas, J.B., C.M.G. Cheung, and S. Panda-Jonas, Updates on the Epidemiology of Age-Related Macular Degeneration. Asia Pac J Ophthalmol (Phila), 2017. 6(6): p. 493-497

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