The biphasic pathophysiology driving the ROP treatment challenge
Retinopathy of prematurity is a biphasic vascular proliferative disease: supplemental oxygen exposure causes initial vascular arrest in phase one, and then relative hypoxia upon return to room air triggers upregulation of pro-angiogenic factors — most prominently vascular endothelial growth factor (VEGF) — leading to pathological retinal neovascularization in phase two. If untreated, this neovascularization can progress to tractional retinal detachment and permanent blindness.
What makes ROP uniquely challenging among neovascular diseases is that physiological and pathological angiogenesis occur concurrently in the developing retina. As the Jilin University group articulates in the retrieved literature, “an ideal therapeutic strategy would selectively inhibit pathological but not physiological angiogenesis.” This constraint shapes every modality in the pipeline — from intravitreal anti-VEGF dosing choices to the timing of laser photocoagulation and the rationale for disease-selective targets like Secretogranin III.
APROP — also termed AP-ROP — is a severe, rapidly progressive form of retinopathy of prematurity involving posterior zone I or posterior zone II disease, characterised by prominent plus disease and a high risk of retinal detachment if not treated urgently. It represents the highest-priority treatment target across the retrieved clinical literature.
The Hannover Medical School group emphasises that pathogenesis extends beyond neovascularization alone: inflammation, photoreceptor loss, and choroidal degeneration in the macular region are also key contributors. According to WHO, ROP is one of the leading causes of avoidable childhood blindness globally, making the therapeutic pipeline a high-priority area for neonatal and ophthalmic research alike.
Retinopathy of prematurity (ROP) is a biphasic vascular proliferative disease in which supplemental oxygen causes initial vascular arrest, followed by relative hypoxia that upregulates VEGF and drives pathological retinal neovascularization — which can progress to tractional retinal detachment and permanent blindness if untreated.
Anti-VEGF intravitreal agents: dosing, efficacy, and recurrence data
Four intravitreal anti-VEGF agents appear across the retrieved clinical evidence for ROP: bevacizumab, ranibizumab, aflibercept, and pegaptanib. As of the most recent literature reviewed, there is no approved drug therapy for ROP in the United States — all agents are used off-label, as explicitly noted by the Tianjin group.
Bevacizumab
Bevacizumab (IVB) — a full-length humanised monoclonal antibody — is administered at doses of 1.25 mg/0.05 mL or 0.625 mg/0.025 mL in retrieved case series. A retrospective cohort of 865 eyes (441 patients) evaluated time to complete vascularisation after IVB, with a mean gestational age of 28 ± 4 weeks. An 8-year retrospective analysis from Romania comparing IVB versus laser in APROP found improved regression rates with bevacizumab. A University of Chicago retrospective of 36 eyes showed unfavourable outcomes in 1 of 22 bevacizumab eyes versus 5 of 14 laser eyes (P=0.002) in APROP, a statistically significant difference favouring the anti-VEGF approach for this severe phenotype.
Ranibizumab
Ranibizumab (IVR) — a monoclonal antibody fragment used at doses of 0.25 mg/0.025 mL or 0.3 mg/0.03 mL — is increasingly proposed as a potentially safer alternative due to lower systemic exposure from its smaller molecular size. A Wills Eye Hospital review summarises evidence supporting ranibizumab as a safer and more effective alternative to bevacizumab for this population. However, a prospective RCT comparing IVR monotherapy versus laser in zone II treatment-requiring ROP (100 eyes, 50 infants) found significantly higher recurrence in the ranibizumab group: 26 of 50 eyes versus 2 of 50 eyes for laser. A Bern University Hospital series reported ranibizumab monotherapy for zone II stage 3 plus disease in 6 eyes of 4 extremely preterm infants with birth weights of 450–745 g.
“In a prospective RCT of 100 eyes, intravitreal ranibizumab monotherapy for zone II ROP produced recurrence in 26 of 50 eyes — compared with just 2 of 50 eyes treated with laser photocoagulation.”
Aflibercept
Aflibercept — a fusion protein VEGF trap — is represented in this dataset exclusively through academic papers. A retrospective Indian case series of 46 eyes documented 100% primary regression at one week and 32.6% complete vascularisation without recurrence, with full vascularisation achieved 15–29 weeks post-injection. No patents were retrieved for aflibercept-specific ROP indications in this dataset.
In a prospective randomised controlled trial of 100 eyes comparing intravitreal ranibizumab monotherapy versus laser photocoagulation for zone II treatment-requiring retinopathy of prematurity, the ranibizumab group had significantly higher recurrence: 26 of 50 eyes recurred versus 2 of 50 eyes in the laser group.
A Sun Yat-sen Memorial Hospital meta-analysis of 10 studies found anti-VEGF associated with significantly increased retreatment incidence (OR 2.52; 95% CI approximately 1.3 and above) versus laser in type-1 and threshold ROP. A Medical University of Graz meta-analysis of 24 observational reports covering 1,457 eyes evaluated the safety profile of VEGF inhibitors, noting that safety concerns in this population rest predominantly on observational — not randomised — literature. According to NIH-registered trial data, RCT evidence for anti-VEGF agents in ROP remains limited compared with the volume of retrospective series.
Track the full anti-VEGF ROP pipeline — dosing, trial status, and assignee landscape — in PatSnap Eureka.
Explore ROP Pipeline Data in PatSnap Eureka →Laser photocoagulation and combination sequencing strategies
Laser photocoagulation — predominantly indirect diode laser — remains the established clinical gold standard and the reference comparator across virtually all anti-VEGF studies in this dataset. Its limitations are well-documented: permanent reduction of visual field, induction of myopia, and destruction of retinal tissue. These drawbacks have motivated both the shift toward anti-VEGF monotherapy and, increasingly, the design of combination and sequencing protocols.
Primary laser evidence
A single-centre retrospective of 110 infants (220 eyes) treated with indirect diode laser from 2006 to 2017 reported a mean gestational age of 28.3 weeks and mean birth weight of 1,121 g. A Hacettepe University study of 195 eyes (99 infants) evaluated bedside diode laser under remifentanil analgesia, reporting one-year structural outcomes. A Kuwait series covering 1999–2003 identified zone of ROP and extraretinal proliferation as risk factors for poor structural and visual outcomes after diode laser.
Combination anti-VEGF plus laser: rationale and timing
The rationale for combination therapy is dual: anti-VEGF injection provides rapid neovascular regression — improving retinal visualisation — while subsequent laser ablates the avascular retina to eliminate the ongoing pro-angiogenic stimulus and reduce recurrence risk. A Narayana Nethralaya commentary highlights ongoing debate about optimal timing of laser following intravitreal ranibizumab in posterior zone 1 APROP, noting published series using laser at 0–8 days (median 3 days) and others at 24–34 days post-injection.
A prospective randomised study from MGM Eye Institute, Raipur (63 eyes, 32 infants with APROP) compared early laser at one week post-intravitreal ranibizumab versus deferred laser at six weeks or at recurrence; both approaches achieved favourable structural outcomes, with the trial providing informative data on laser spot counts and refractive error at six months. Xinhua Hospital (Shanghai Jiao Tong University) reported a retrospective series of 37 eyes (20 AP-ROP patients with vitreous haemorrhage) treated with intravitreal ranibizumab (0.25 mg) followed by photocoagulation at a mean interval of 4.8 ± 2.9 weeks; 96.6% of eyes showed rapid vitreous haemorrhage absorption after intravitreal ranibizumab, facilitating subsequent laser delivery.
Keimyung University (Korea) described a posterior pole-sparing laser technique combined with intravitreal bevacizumab in 11 eyes of 6 infants with advanced zone I ROP — preserving the posterior pole from ablation while achieving neovascular regression. Guangzhou Women and Children’s Medical Center has a prospective protocol evaluating prophylactic peripheral photocoagulation to treat persistent avascular retina following anti-VEGF in ROP, using fundus fluorescein angiography to guide treatment decisions.
In a retrospective series of 37 eyes with AP-ROP complicated by vitreous haemorrhage, 96.6% showed rapid haemorrhage absorption following intravitreal ranibizumab (0.25 mg), enabling subsequent laser photocoagulation at a mean interval of 4.8 ± 2.9 weeks — a clinically important sequencing advantage in cases where haemorrhage would otherwise preclude direct laser delivery.
Beyond VEGF: emerging molecular targets and preclinical candidates
The most promising innovation signals in this dataset come from preclinical work targeting molecular pathways that operate upstream of, or independently from, the VEGF axis — addressing the fundamental limitation of current therapy: the inability to distinguish pathological from physiological angiogenesis in the developing retina.
Secretogranin III (Scg3)
Scg3 is a disease-selective angiogenic factor that activates pathological but not physiological vasculature. The Tianjin Medical University group characterised a full-length humanised anti-Scg3 monoclonal antibody in oxygen-induced retinopathy (OIR) mouse models, claiming superior selectivity over VEGF inhibitors — targeting pathological neovessels while sparing normal vessel development. This represents a precision alternative to pan-VEGF inhibition, though it remains preclinical in this dataset.
EMP2 (Epithelial Membrane Protein 2)
EMP2 is a tetraspan protein expressed in retinal pigment epithelium (RPE) that controls VEGF production via protein scaffolding. The UCLA/Stein Eye Institute group demonstrated that Emp2 knockout mice showed reduced neovascularisation in OIR, establishing EMP2 as a potential upstream regulator of VEGF in the RPE-mediated angiogenic response and a druggable target for ROP. This work remains preclinical.
MEG3 (Maternally Expressed Gene 3)
MEG3 is a long non-coding RNA that acts as a suppressor of the PI3K/serine-threonine kinase/VEGF pathway and pro-inflammatory factors. Retrieved evidence shows that MEG3 overexpression via lentiviral vector inhibited retinal neovascularisation in OIR mice, with a proposed future clinical application. All MEG3 work in this dataset is preclinical.
A humanised anti-Scg3 (Secretogranin III) monoclonal antibody demonstrated superior disease-selectivity over VEGF inhibitors in oxygen-induced retinopathy mouse models, targeting pathological but not physiological vasculature — a key advantage over current pan-VEGF approaches for retinopathy of prematurity.
Additional preclinical candidates
- Resveratrol: A natural compound VEGF-binding inhibitor evaluated in murine OIR by the Hong Kong University of Science and Technology group, delivered by both intravitreal injection and topical eye drops.
- 2-Methoxyestradiol (2-ME) nanoemulsion: Intravitreal injection evaluated in a Sprague-Dawley rat OIR model at two nanoparticle concentrations by the Ain Shams University group.
- Vascular homing peptide CAR (CARSKNKDC): Systemically administered peptide demonstrating selective targeting to preretinal neovessels in OIR, proposed as a retinal-targeted drug delivery vehicle by the Tampere University Hospital group.
- Systemic propranolol: An antiangiogenic agent targeting adrenergic signalling being evaluated in ROP, with safety concerns raised about effects on visual and olfactory system plasticity in the developing infant.
According to WIPO patent data, the absence of retrieved patent filings for these novel targets in this dataset suggests that the preclinical innovation around Scg3, EMP2, and MEG3 has not yet translated into formal IP protection activity — representing a potential early-mover opportunity for developers monitoring the ROP pipeline. The retrieved activity is entirely literature-driven, spanning institutions across Asia, Europe, the Middle East, and the Americas.
Monitor emerging ROP targets and preclinical candidates across global patent and literature databases with PatSnap Eureka.
Search ROP Targets in PatSnap Eureka →Systemic safety signals and the IGF-1 developmental window
The central safety concern in the ROP drug pipeline is systemic VEGF suppression in preterm infants during a critical developmental window equivalent to the third trimester of gestation — a period in which IGF-1 signalling and adrenergic signalling are essential for normal retinal and multi-organ maturation.
The Xinhua Hospital neonatology group prospectively measured serum VEGF before and at 1, 3, and 7 days after intravitreal ranibizumab (0.25 mg/eye), documenting measurable serum VEGF reduction in preterm infants following intravitreal injection. This systemic leakage of anti-VEGF agents — more pronounced with full-length antibodies like bevacizumab than with antibody fragments like ranibizumab — underpins the preference for ranibizumab in some centres despite its higher zone II recurrence rate.
“An ideal therapeutic strategy would selectively inhibit pathological but not physiological angiogenesis” — a challenge that defines the entire ROP drug pipeline, from anti-VEGF dosing decisions to the pursuit of disease-selective targets like Scg3.
The University of Gothenburg (Sahlgrenska Academy) raises concern that blocking normal angiogenesis via VEGF inhibition in a period coincident with critical IGF-1–dependent developmental windows may produce lasting harm to multiple organ systems beyond the retina. The same group identifies systemic propranolol — being evaluated as an antiangiogenic in ROP via adrenergic system modulation — as carrying analogous risks for visual and olfactory system plasticity in the developing infant.
A retrieved result from Zunyi Medical University adds an anti-inflammatory dimension to the ROP treatment picture: ranibizumab significantly reduced serum interleukin-17A (IL-17A) levels in treated premature infants, suggesting that anti-VEGF therapy in ROP may confer benefits beyond direct angiogenesis inhibition. The Pomeranian Medical University series combined diode laser with systemic dexamethasone in 36 eyes of 18 infants with AP-ROP and threshold 3 ROP, achieving favourable anatomical results in 32 eyes (88.88%), suggesting a role for concurrent anti-inflammatory adjuncts alongside laser in severe disease.
As of the most recent literature reviewed, there is no approved drug therapy for retinopathy of prematurity in the United States. All intravitreal anti-VEGF agents — including bevacizumab, ranibizumab, and aflibercept — are used off-label for ROP treatment.
The geographic breadth of contributing institutions — spanning China, India, South Korea, Germany, Poland, Austria, Switzerland, Portugal, Romania, Saudi Arabia, Israel, Turkey, Kuwait, the United States, and Canada — reflects the global clinical burden of ROP and the distributed nature of innovation in this space. High-volume Chinese centres, particularly Peking University People’s Hospital and Xinhua Hospital (Shanghai Jiao Tong University), contribute the largest clinical datasets. Standards for ROP screening and treatment are further shaped by guidance from bodies including the American Academy of Ophthalmology, whose recommendations influence clinical practice in many of the geographies represented in this dataset. The PatSnap Insights blog covers further developments in ophthalmic drug pipeline intelligence and innovation tracking.