Stereotactic radiotherapy in neovascular age-related macular degeneration: Real-life efficacy and morphological evaluation of the outer retina-choroid complex

Real-world experience of using stereotactic radiotherapy combined with anti-vascular endothelial growth factor to treat neovascular AMD

INTRODUCTION

Adjunctive treatment or longer-acting drugs are required to treat nAMD to help ease burdens for patients and hospital clinics alike. Stereotactic therapy is one such option, providing a reduction in the number of injections over time.

OBJECTIVE

To determine the clinical outcomes in a cohort of patients with nAMD receiving a combination therapy of stereotactic radiotherapy (SRT) with intravitreal anti-VEGF injections (IVI).

METHOD

A retrospective analysis of 74 patients with nAMD, who had received IVI and SRT (16 Gray maximum dose to the macula) at a large tertiary university eye hospital, between March 2018 and September 2019 was performed. The number of IVIs, visual acuity (VA), and central retinal thickness (CRT) were evaluated at 12, 24, and 36 months after patients received SRT and compared to the same time interval prior to SRT.

RESULTS

Follow-up data at 12, 24, and 36 months following and prior to SRT was available for 74, 48, and 22 patients respectively. Overall there was a significant reduction in the number of injections post-SRT. Twelve months following SRT, the median number of IVI was reduced by 1 (p < 0.05). The reduction in the median number of IVI was significantly reduced by 3 and 6 injections at 24- and 36-month follow-up respectively (p < 0.05). The CRT was significantly reduced post-SRT compared to the baseline values at all time periods. There was no statistically significant difference in VA at 12-month follow-up compared to baseline. The VA, however, significantly decreased at 24- and 36-month follow-up (p < 0.05).

CONCLUSION

A therapy combining SRT with IVI has shown an overall reduction in the number of injections required in nAMD patients at 12, 24, and 36 months following SRT compared to IVI treatment alone. These real-world outcomes are comparable to other studies while also confirming the maintenance of the reduced frequency of required IVI for patients with nAMD.

Stereotactic radiotherapy for neovascular age-related macular degeneration (STAR): a pivotal, randomised, double-masked, sham-controlled device trial

BACKGROUND

Neovascular age-related macular degeneration (nAMD) is a leading cause of blindness. The first-line therapy is anti-vascular endothelial growth factor (anti-VEGF) agents delivered by intravitreal injection. Ionising radiation mitigates key pathogenic processes underlying nAMD, and therefore has therapeutic potential. STAR aimed to assess whether stereotactic radiotherapy (SRT) reduces the number of anti-VEGF injections required, without sacrificing visual acuity.

METHODS

This pivotal, randomised, double-masked, sham-controlled trial enrolled participants with pretreated chronic active nAMD from 30 UK hospitals. Participants were randomly allocated in a 2:1 ratio to 16-Gray (Gy) SRT delivered using a robotically controlled device or sham SRT, stratified by treatment centre. Eligible participants were aged 50 years or older and had chronic active nAMD, with at least three previous anti-VEGF injections, including at least one in the last 4 months. Participants and all trial and image reading centre staff were masked to treatment allocation, except one unmasked statistician. The primary outcome was the number of intravitreal ranibizumab injections required over 2 years, tested for superiority (fewer injections). The main secondary outcome was Early Treatment Diabetic Retinopathy Study visual acuity at two years, tested for non-inferiority (five-letter margin). The primary analysis used the intention-to-treat principle, and safety was analysed per-protocol on participants with available data. The study is registered with ClinicalTrials.gov (NCT02243878) and is closed for recruitment.

FINDINGS

411 participants enrolled between Jan 1, 2015, and Dec 27, 2019, and 274 were randomly allocated to the 16-Gy SRT group and 137 to the sham SRT group. 240 (58%) of all participants were female, and 171 (42%) of all participants were male. 241 participants in the 16-Gy SRT group and 118 participants in the sham group were included in the final analysis, and 409 patients were treated and formed the safety population, of whom two patients allocated to sham treatment erroneously received 16-Gy SRT. The SRT group received a mean of 10·7 injections (SD 6·3) over 2 years versus 13·3 injections (5·8) with sham, a reduction of 2·9 injections after adjusting for treatment centre (95% CI -4·2 to -1·6, p<0·0001). The SRT group best-corrected visual acuity change was non-inferior to sham (adjusted mean letter loss difference between groups, -1·7 letters [95% CI -4·2 to 0·8]). Adverse event rates were similar across groups, but reading centre-detected microvascular abnormalities occurred in 77 SRT-treated eyes (35%) and 13 (12%) sham-treated eyes. Overall, eyes with microvascular abnormalities tended to have better best-corrected visual acuity than those without. Fewer ranibizumab injections offset the cost of SRT, saving a mean of £565 per participant (95% CI -332 to 1483).

INTERPRETATION

SRT can reduce ranibizumab treatment burden without compromising vision.

FUNDING

Medical Research Council and National Institute for Health and Care Research Efficacy and Mechanism Evaluation Programme.

Polypoidal Choroidal Vasculopathy after Stereotactic Radiotherapy for Neovascular Age-Related Macular Degeneration: A Case Report with Long-Term Follow-Up

Several adjunct therapies to the gold standard anti-vascular endothelial growth factor (anti-VEGF) intravitreal injections have been discussed for the treatment of neovascular age-related macular degeneration (nAMD). Low-dose stereotactic radiotherapy (SRT) showed the potential to lower the treatment burden by reducing the anti-VEGF treatment frequency at least over 2–3 years but was associated with retinal microvascular abnormalities in a few cases. We report a 6-year follow-up of a case with bilateral nAMD under anti-VEGF treatment which developed multiple polypoid choroidal vasculopathy (PCV) lesions in the eye adjunct treated with low-dose SRT. The fellow eye suffering from nAMD for the same period of time but never been treated with SRT did not show PCV during the long-term follow-up. We hope to increase the awareness of possible choroidal changes such as PCV in similar patients by sharing this report.

In vitro evaluation of simulated stereotactic radiotherapy for wet age-related macular degeneration on three different cell lines

Low energy stereotactic radiotherapy has been proposed for the treatment of neovascular age related macular degeneration. We investigated the in vitro effect of the radiotherapy on pericytes, retinal pigment epithelium and endothelial cells. Primary human retinal pigment epithelium cells, human umbilical vein endothelial cells and human pericytes from Placenta were cultivated. In a pairwise protocol, one plate was irradiated at a dose of 16 Gy, while the second plate served as a non-irradiated control. Thereafter, cells were cultivated either in serum-free (non-permissive) or serum-stimulated (permissive) conditions. A life/dead assay, an XTT and a BrdU assay were performed up to 7 days after irradiation. No cell death occurred at any timepoint in any cell line after treatment nor in the control. Compared to the unirradiated controls, cell viability and metabolic activity were significantly reduced in irradiated cells in the XTT assay, except for non-permissive RPE cells. In the BrdU assay, proliferation was inhibited. While no cell death was detected in vitro, viability and proliferative capacity of all cell lines were significantly reduced. Therefore, it seems that low energy stereotactic radiotherapy inhibits angiogenesis without a direct induction of apoptosis but influencing microvascular function and stability.

Three-year clinical and optical coherence tomography follow-up after stereotactic radiotherapy for neovascular age-related macular degeneration

PURPOSE

The long-term clinical outcome of adjuvant stereotactic radiotherapy (SRT) in neovascular age-related macular degeneration (nAMD) patients was evaluated.

METHODS

This case-control study included patients with unilateral nAMD, who underwent SRT complementary to standard anti-VEGF treatment. Only patients with monthly follow-up over at least three years were considered. Number of intravitreal injections, visual acuity (VA), central retinal thickness (CRT), and subfoveal choroidal thickness (SFCT) were evaluated and compared to baseline as well as to an age- and gender-matched control group, who received anti-VEGF monotherapy.

RESULTS

Twenty patients were irradiated and had complete follow-up. Cumulatively, SRT patients needed significantly less injections than non-irradiated ones over three years (14 vs. 18, p ​= ​0.014), while median VA did not show statistically significant changes (0.4 logMAR at baseline to 0.65 logMAR at final follow-up, p ​= ​0.061). CRT remained steady, but SFCT showed a continuous thinning of almost 50 ​μm (p ​= ​0.031) in irradiated patients over three years. Multiple linear regression analysis revealed that SFCT and VA at time of irradiation are significant prognostic factors of VA change in SRT patients over the following three years (F(2,17) ​= ​23.946, p<0.001, R² of 0.738).

CONCLUSIONS

SRT significantly reduced the cumulative anti-VEGF treatment burden over three years, however, this was mainly driven by the results of the first year after irradiation. A thinner SFCT at time of irradiation was associated with poorer visual outcome. While further research and investigation are warranted to elucidate the underlying pathogenesis, SFCT could be a potential biomarker when evaluating a patient's suitability for SRT.

Microvascular abnormalities and long-term efficacy after stereotactic radiotherapy under continued intravitreal anti-VEGF treatment for neovascular AMD

Background

For treatment of neovascular age-related macular degeneration (nAMD), multiple intravitreal injections of drugs targeting vascular endothelial growth factors (VEGF) result in a high burden for patients and healthcare systems. Low-energy stereotactic radiotherapy (SRT) might reduce the anti-VEGF need. This study evaluated the long-term efficacy and safety of adjunct SRT to anti-VEGF injections in a treat-and-extend regimen in nAMD.

Methods

50 consecutive patients were followed 3 years after single-session SRT, a safety analysis including standardised study imaging, and a reading centre based image analysis was performed after 2 years.

Results

After increase from baseline (4.24±0.66 weeks) to 12 months (7.52±3.05 weeks, p<0.001), mean recurrence-free anti-VEGF treatment interval remained stable at 24 (7.40±3.17, p=0.746) and 36 months (6.89±3.00, p=0.175). Mean visual acuity change was −5.8±15.9 and −11.0±20.1 letters at 24 and 36 months, respectively. 36% of eyes showed microvascular abnormalities (MVAs) on colour fundus photography and/or fluoresceine angiography most frequently located in parafoveal inferior and nasal regions.

Conclusion

In real life, low-energy SRT was associated with a reduced anti-VEGF injection frequency through year 3. However, due to an observed visual acuity reduction and remarkable number of MVAs, a close follow-up of these patients is recommended. The real-life use, optimal treatment schedule and dose should be rediscussed critically.

Low-Energy Stereotactic Radiotherapy for Treatment of Exudative Age-Related Macular Degeneration in a Treat-and-Extend Regimen

BACKGROUND AND OBJECTIVE

To evaluate the effectiveness and safety of low-energy stereotactic radiotherapy (SRT) combined with anti-vascular endothelial growth factor (VEGF) treatment following a treat-and-extend regimen (TER) in wet age-related macular degeneration (AMD).

PATIENTS AND METHODS

Before/after SRT, the authors compared retrospective consecutive case series of 50 patients requiring frequent anti-VEGF treatment (every 4 or 6 weeks) in wet AMD, treated with a single session of SRT and TER (same manner pre/post-SRT). Outcomes were visual acuity (VA), recurrence-free interval, and central retinal thickness (CRT).

RESULTS

After SRT, CRT was reduced from baseline (407.3 μm ± 153.2 μm) to 12 months (320.2 μm ± 112.1 μm; P < .001), with statistical significance from month 2 onward. VA was stable for 12 months (64.0 letters ± 15.1 letters vs. 63.6 letters ± 16.2 letters). The mean recurrence-free interval increased from 4.24 weeks ± 0.66 weeks to 7.52 weeks ± 3.05 weeks at 12 months (P < .001). No severe side effects were observed.

CONCLUSION

Low-energy SRT, combined with anti-VEGF TER, was associated with reduced injection frequency and preserved VA during 12 months of follow-up. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:86-93.].

Subfoveal Choroidal Thickness as a Potential Predictor of Clinical Response to Stereotactic Radiotherapy for Neovascular Age-Related Macular Degeneration

BACKGROUND AND OBJECTIVE

Stereotactic radiotherapy (SRT) is a new adjuvant treatment modality that has been shown to reduce the need for repetitive intravitreal injections (IVIs) in patients with neovascular age-related macular degeneration (nAMD). The authors aimed to determine baseline predictors of clinical response to SRT.

PATIENTS AND METHODS

This was a retrospective, observational case series of patients with nAMD who underwent SRT and subsequently had at least 12 months of complete follow-up. After SRT and one mandatory IVI, patients were examined every 4 weeks and received further treatment on a pro re nata basis. Examination included enhanced depth imaging spectral-domain optical coherence tomography (SD-OCT) to measure subfoveal choroidal thickness (SFCT) and central macular thickness (CMT). Patients' data were retrieved from medical records and included demographics, disease duration, lesion size, best-corrected visual acuity (BCVA), previous number of IVIs, and type of drug applied.

RESULTS

A total of 35 eyes of 35 patients (76.23 years ± 7.05 years) were included, and 21 eyes (60%) responded well to SRT. The annual injection rate decreased from 6.86 before SRT to 3.46 afterward, whereas BCVA improved from 0.49 logMAR at baseline to 0.37 logMAR at final follow-up. From a morphologic point of view, CMT and SFCT decreased by 71 μm and 37 μm, respectively, at 12-month follow-up compared to baseline. Of all investigated parameters, only SFCT proved to be significant, as a higher baseline SFCT was found to be a strong negative predictor for the number of IVIs needed after SRT (regression coefficient: -0.678; P < .001).

CONCLUSIONS

Baseline SFCT may help predict which patients with nAMD will respond more favorably to SRT. The authors found eyes with a thicker baseline SFCT needed fewer IVIs after SRT. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:320-328.].

Subfoveal choriocapillaris, Sattler's and Haller's layer thickness predict clinical response to stereotactic radiotherapy in neovascular age-related macular degeneration patients

Purpose

To evaluate the significance of choroidal substructure analysis in predicting the clinical response to adjuvant stereotactic radiotherapy (SRT) in neovascular age-related macular degeneration (nAMD) patients.

Methods

Patients with nAMD, who underwent SRT (baseline) in addition to common intravitreal injections (IVIs) and subsequently had at least 12 months of complete follow-up, were enrolled. In a post hoc analysis, optical coherence tomography (OCT) data were reviewed, and subfoveal choroidal thickness (CT) as well as the thickness of choroidal substructures, such as choriocapillaris (CC), Sattler's layer (SL), and Haller's layer (HL), was measured to determine if these influenced SRT efficacy.

Results

A total of 35 eyes of 35 patients were included. While each of the 4 choroidal metrics significantly forecasts the clinical response to SRT, combining them all together produced the most reliable prediction model.

Conclusion

In terms of clinical response to SRT in nAMD patients, choroidal substructure analysis does improve the quality of the prediction model when combined with subfoveal CT.

IRay therapy as an adjuvant therapy in newly diagnosed patients with neovascular age-related macular degeneration

OBJECTIVES

To determine the safety and efficacy at 12 months of follow-up after stereotactic radiotherapy in combination therapy with intravitreal ranibizumab injections in treatment naïve patients with neovascular age-related macular degeneration.

METHODS

Retrospective data analysis in patients who received stereotactic radiotherapy (IRay Therapy) during the induction phase of intravitreal ranibizumab injections and a monotherapy control group.

RESULTS

The baseline VA in the IRay and control group was 59.87 and 59.12 letters respectively. The real world visual acuity outcomes for the IRay group showed a mean gain of +3.0 letters at 12 months. The historical control group had a mean change of - 0.3 letters. The average number of injections for the IRay group and control group over 12 months was 4.45 and 5.64, respectively with three loading injections. Excluding the loading phase, the difference over 12 months was a 45.2% reduction in injections (P < 0.001). The number of subjects in the IRay group that didn't require further injections following the loading phase was 45.5 vs. 24.0% control group (P = 0.005). The difference in mean change in central macular thickness from baseline is significant at 6 (P = 0.010) and 12 months (P < 0.01). There were no safety concerns with the IRay therapy group.

CONCLUSIONS

Stereotactic radiotherapy in the induction phase of intravitreal injections of ranibizumab for treatment naïve patients with neovascular age-related macular degeneration, resulted in improved visual outcome, statistically fewer injections and statistically drier macular at 12 months, compared to historical controls treated with monotherapy intravitreal ranibizumab injections.

Potential selection bias in candidates for stereotactic radiotherapy for neovascular AMD

PURPOSE

Stereotactic radiotherapy (SRT, IRay) was able to reduce the need for intravitreal injections of anti-VEGF (IVI) in patients with neovascular AMD (nAMD) in a phase II randomized clinical trial. Certain morphologic characteristics, such as lesion size < 4 mm² or lack of fibrosis, were associated with a better response. The purpose of this cross-sectional study was to investigate eligibility for SRT in a clinical routine setting and to compare clinical features of eligible and non-eligible patients.

METHODS

Cross-sectional study of 468 patients treated for nAMD in one study center within a period of 4 months. Clinical features, such as visual acuity or number of IVI since diagnosis and within 6/12 months, as well as the presence for exclusion criteria for SRT were analyzed. Exclusion criteria were sub-divided into lesion-associated (relevant fibrosis, lesion size > 4 mm², PE tear), ocular comorbidity (e.g., macular comorbidity, vascular disease) and systemic comorbidity (e.g., dementia or tremor).

RESULTS

Exclusion criteria were met by 255 patients (54.5%). Exclusion was most dominantly associated with lesion-associated criteria (80.0%) and less often with ocular (20.8%) or systemic (9.4%) comorbidity. A total of 213 patients (45.5%) fulfilled eligibility criteria. Eligible patients had a better VA at time of analysis (0.36 vs. 0.56 logMAR, p < 0.0001) and at baseline (0.38 vs. 0.56 logMAR, p < 0.0001) compared to non-eligible patients. The numbers of previous intravitreal injections since diagnosis in strictly PRN-treated patients served as a surrogate marker for lesion activity and was comparable within the last 6/12 months. Non-eligible patients had a higher number of different anti-VEGF drugs (1.8 vs. 1.6, p = 0.038).

CONCLUSIONS

SRT in addition to anti-VEGF can be an option in every second patient with nAMD. Due to morphological exclusion criteria, patients eligible for SRT had a better VA and a better clinical response compared to non-eligible patients.

Changes in Peripapillary Nerve Fiber Layer Thickness after Adjuvant Stereotactic Radiotherapy in Patients with Neovascular Age-Related Macular Degeneration

PURPOSE

To evaluate the effect of stereotactic radiotherapy (SRT) in conjunction with intravitreal injections (IVI) of anti-vascular endothelial growth factor (anti-VEGF) drugs on peripapillary retinal nerve fiber layer (pRNFL) thickness in patients with neovascular age-related macular degeneration (nAMD).

METHODS

This was a retrospective, observational case series of patients with nAMD, who underwent SRT and subsequently had at least 12 months of complete follow-up. After SRT and one mandatory IVI, patients were examined monthly and received further treatment on a pro re nata basis. Examination included spectral-domain optical coherence tomography of the optic disc to measure pRNFL thickness. Patients' data were retrieved from medical records including demographics, disease duration, best-corrected visual acuity, previous number of intravitreal injections, and the type of drug applied.

RESULTS

A total of 35 eyes of 35 patients (76.23 ± 7.05 years) were included. The mean duration of nAMD at time of irradiation was 34.57 ± 16.96 months. During that time, patients received a mean total number of 15.83 ± 6.29 intravitreal injections, 6.86 ± 1.57 within the last 12 months before SRT. After SRT, on average 3.46 ± 2.09 injections were administered over 12 months, resulting in a mean total number of 19.29 ± 6.92 injections at final follow-up. The mean global pRNFL thickness was 97.23 ± 12.55 µm at time of irradiation, 95.54 ± 11.07 µm at 6 month (P = 0.299), and 95.29 ± 12.07 µm at 12 month (P = 0.373) follow-up.

CONCLUSION

SRT in conjunction with anti-VEGF injections did not lead to any significant change in pRNFL thickness over 12 months in patients with nAMD. However, long-term results are not yet available. Therefore, prospective studies with longer follow-up are needed to corroborate these findings.

Recent developments in age-related macular degeneration: a review

Background

Visual impairment in elderly people is a considerable health problem that significantly affects quality of life of millions worldwide. The magnitude of this issue is becoming more evident with an aging population and an increasing number of older individuals.

Objective

The objective of this article was to review the clinical and pathological aspects of age-related macular degeneration (AMD), diagnostic tools, and therapeutic modalities presently available or underway for both atrophic and wet forms of the disease.

Methods

An online review of the PubMed database was performed, searching for the key words. The search was limited to articles published since 1980 to date.

Results

Several risk factors have been linked to AMD, such as age (>60 years), lifestyle (smoking and diet), and family history. Although the pathogenesis of AMD remains unclear, genetic factors have been implicated in the condition. Treatment for atrophic AMD is mainly close observation, coupled with nutritional supplements such as zinc and antioxidants, whereas treatment of wet AMD is based on targeting choroidal neovascular membranes.

Conclusion

Identification of modifiable risk factors would improve the possibilities of preventing the progression of AMD. The role of anti-vascular endothelial growth factor (anti-VEGF) agents has transformed the therapeutic approach of the potentially blinding disease “wet AMD” into a more favorable outcome.

Erratum: Stereotactic radiotherapy in neovascular age-related macular degeneration: Real-life efficacy and morphological evaluation of the outer retina-choroid complex: Erratum

[This corrects the article DOI: 10.1097/MD.0000000000005729.].