Bevacizumab dosing every 2 weeks for neovascular age-related macular degeneration refractory to monthly dosing

Towards a population pharmacokinetic/pharmacodynamic model of anti-VEGF therapy in patients with age-related macular degeneration

PURPOSE

To develop a population pharmacokinetic/pharmacodynamic model (popPKPD) of intravitreal bevacizumab treatment for neovascular age-related macular degeneration (nAMD) patients to learn about the PK/PD relationship and utilise it for dosing regimen decisions on future nAMD patients.

METHODS

The Greater Manchester Avastin for Neovascularisation (GMAN) randomised clinical trial data was retrospectively utilised, and the best-corrected visual acuity (BCVA) and central macular retinal thickness (CRT, measured by optical coherence tomography) were the PD inputs to the model. Using the nonlinear mixed-effects method, the best PKPD structural model was investigated, and the clinical significance of the two different dosing treatment regimens (as-needed versus routine) was evaluated.

RESULTS

A structural model to describe the change of BCVA from the baseline of nAMD patients was successfully obtained based on the turnover PD model concept (drug stimulates the "visual acuity response production"). The popPKPD model and simulation indicate that the routine regimen protocol improves patient visual outcome compared to the as-needed protocol. For the change in CRT, the turnover structural PKPD model was too demanding to fit to the given clinical data.

CONCLUSIONS

This is the first popPKPD attempt in nAMD treatment that shows the potential of this strategy to understand/inform the dosing regimen. Clinical trials with richer PD data will provide the means to build more robust models.

SUSTAINED BIWEEKLY AFLIBERCEPT FOR REFRACTORY NEOVASCULAR AGE-RELATED MACULAR DEGENERATION: The Prospective TRISTAR Study

PURPOSE

To assess the safety and efficacy of biweekly (every 2 weeks) intravitreal aflibercept injections (IAI) 2 mg in eyes with refractory neovascular age-related macular degeneration (NVAMD).

METHODS

A prospective, single-arm, interventional study was conducted. Eyes with refractory NVAMD received six biweekly IAIs through week 12, followed by a 4-week treatment pause until week 16. Eyes with residual subretinal fluid (SRF) at week 16 were randomized 1:1 to either four additional biweekly IAIs or to 4-week (q4W) IAI dosing through week 24. All eyes were subsequently treated q4W through week 52.

RESULTS

Enrolled eyes (n = 22) had persistent SRF despite a mean of 11.8 injections over the prior 12 months. One patient developed endophthalmitis at week 12. There were no additional drug/procedure-related adverse events. Best-corrected visual acuity (BCVA) improved significantly from baseline to week 14 (2.52 letters, P < 0.001). The mean central subfield thickness (CST) was also significantly improved at week 14 (-31.9 µ m, P < 0.001) with eight of 22 eyes achieving complete SRF resolution. Only two of eight eyes remained free of SRF at week 16, with a corresponding increase in mean CST of 26.7 µ m compared with week 14. By week 52, improvements in BCVA and CST were lost.

CONCLUSION

In patients with refractory NVAMD-related SRF, sustained biweekly IAIs resulted in significant functional and anatomical improvements during biweekly dosing. These gains, however, were lost on return to monthly dosing. These findings suggest that efforts to reduce refractory SRF in NVAMD with biweekly dosing may provide added benefit compared with standard of care treatment if biweekly dosing is sustained.

Role of Oxidative Stress in Ocular Diseases: A Balancing Act

Redox homeostasis is a delicate balancing act of maintaining appropriate levels of antioxidant defense mechanisms and reactive oxidizing oxygen and nitrogen species. Any disruption of this balance leads to oxidative stress, which is a key pathogenic factor in several ocular diseases. In this review, we present the current evidence for oxidative stress and mitochondrial dysfunction in conditions affecting both the anterior segment (e.g., dry eye disease, keratoconus, cataract) and posterior segment (age-related macular degeneration, proliferative vitreoretinopathy, diabetic retinopathy, glaucoma) of the human eye. We posit that further development of therapeutic interventions to promote pro-regenerative responses and maintenance of the redox balance may delay or prevent the progression of these major ocular pathologies. Continued efforts in this field will not only yield a better understanding of the molecular mechanisms underlying the pathogenesis of ocular diseases but also enable the identification of novel druggable redox targets and antioxidant therapies.

Monthly Alternating Injections of Aflibercept and Bevacizumab for Neovascular Age-Related Macular Degeneration

We investigated the efficacy of monthly alternating injections of aflibercept and bevacizumab (MAAB) for maintenance treatment in patients with neovascular age-related macular degeneration (AMD) who showed improvement with the initial monthly injections but presented with rapid worsening after conversion to bimonthly injections. We included 72 patients with neovascular AMD who showed improvement with loading injections of aflibercept. For maintenance treatment, bevacizumab was administered every alternate month between the bimonthly aflibercept injections in 24 (33.3%) eyes showing worsening (MAAB group). The other eyes were treated with aflibercept (BiA group) bimonthly. Baseline low retinal thickness, thick choroid, and presence of intraretinal fluid were associated with worsening after extending the injection intervals. Visual improvement was lower in the MAAB group than in the BiA group, but the final visual outcomes were comparable. Additional bevacizumab stabilized the early fluctuation of retinal thickness, thus maintaining long-term visual stability without increasing the risk of geographic atrophy or disciform scar until the second year. Previously treated eyes or those with polypoidal choroidal vasculopathy responded less to the initial loading doses and showed worsening under the bimonthly regimen. MAAB was effective in preventing anatomical and functional deterioration when bimonthly aflibercept proved insufficient for the maintenance treatment of neovascular AMD.

Anti-VEGF-Resistant Retinal Diseases: A Review of the Latest Treatment Options

Anti-vascular endothelial growth factor (anti-VEGF) therapy currently plays a central role in the treatment of numerous retinal diseases, most notably exudative age-related macular degeneration (eAMD), diabetic retinopathy and retinal vein occlusions. While offering significant functional and anatomic benefits in most patients, there exists a subset of 15–40% of eyes that fail to respond or only partially respond. For these cases, various treatment options have been explored with a range of outcomes. These options include steroid injections, laser treatment (both thermal therapy for retinal vascular diseases and photodynamic therapy for eAMD), abbreviated anti-VEGF treatment intervals, switching anti-VEGF agents and topical medications. In this article, we review the effectiveness of these treatment options along with a discussion of the current research into future directions for anti-VEGF-resistant eyes.

High frequency SD-OCT follow-up leading to up to biweekly intravitreal ranibizumab treatment in neovascular age-related macular degeneration

A remarkable proportion of neovascular age-related macular degeneration (nAMD) patients respond rather poorly to ranibizumab treatment, in spite of the minimum 4-week follow-up and treatment interval. Usually, retreatments are based on nAMD activity as evaluated by Spectral-domain Optical coherence Tomography (SD-OCT), biomicroscopic fundus examination and visual acuity changes. In this prospective pilot study, we aimed to study SD-OCT changes in a high-frequent follow-up manner (weekly (month 0–6), biweekly (month 7–12)) throughout the first year, which consequently led to intravitreal ranibizumab being administered up to biweekly. Best corrected visual acuity (BCVA) was already significantly improved at week 2. Central retinal thickness (CRT), intraretinal and subretinal fluid (SRF) were significantly improved from week 1 onwards. Half of the patients showed nAMD activity at week 2 or 3 and received the first retreatment earlier than 4 weeks after baseline injection. In total, 46% of retreatments were already applied 2 or 3 weeks after the previous treatment. Greater range of CRT and SRF fluctuation during follow-up was associated with lower final BCVA. Lower baseline BCVA and better SRF improvement at week 2 was associated with greater BCVA improvement. In conclusion, high-frequency SD-OCT follow-up provided a good option for adapting treatment in nAMD individually.

New insights into oxidative stress and immune mechanisms involved in age-related macular degeneration tackled by novel therapies

The prevalence of age-related macular degeneration (AMD) has increased in the last years. Although anti-VEGF agents have improved the prognosis of exudative AMD, dry AMD has still devastating effects on elderly people vision. Oxidative stress and inflammation are mechanisms involved in AMD pathogenesis and its progression. Molecular pathways involving epidermal growth factor receptor (EGFR), bone morphogenetic protein (BMP4) and the nuclear erythroid related factor 2 (Nrf2) are behind oxidative stress in AMD due to their participation in antioxidant cellular pathways. As a consequence of the disbalance produced in the antioxidant mechanisms, there is an activation of innate and adaptative immune response with cell recruitment, changes in complement factors expression, and modification of cellular milieu. Different therapies are being studied to treat dry AMD based on the possible effects on antioxidant molecular pathways or their action on the immune response. There is a wide range of treatments presented in this review, from natural antioxidant compounds to cell and gene therapy, based on their mechanisms. Finally, we hypothesize that alpha-1-antitrypsin (AAT), an anti-inflammatory and immunomodulatory molecule that can also modulate antioxidant cellular defenses, could be a good candidate for testing in AMD. This article is part of the special ssue on 'The Quest for Disease-Modifying Therapies for Neurodegenerative Disorders'.

Clinical characteristics and visual outcomes of non-resolving subretinal fluid in neovascular AMD despite continuous monthly anti-VEGF injections: a long-term follow-up

PURPOSE

To describe the clinical characteristics and visual outcomes of neovascular age-related macular degeneration (NV-AMD) patients with irregular pigment epithelium detachment (PED) and non-resolving subretinal fluid (SRF) despite continuous monthly injections of anti-vascular endothelial growth factor (VEGF).

METHODS

This is a retrospective case series, including NV-AMD patients treated in a tertiary academic practice. Inclusion criteria were NV-AMD diagnosis, with irregular PED, and non-resolving SRF treated with continuous monthly anti-VEGF intravitreal injections. Data collection included best corrected visual acuity (BCVA), central macular thickness (CMT), sub-foveal choroidal thickness (SFCT), and type and location of PED as seen on optical coherence tomography (OCT).

RESULTS

A total of 738 patients with NV-AMD underwent anti-VEGF injections during the follow-up period and 20 eyes of 19 patients (14 females and 5 males) met the inclusion criteria. Average age was 81.7 ± 6.6 years, mean follow-up time was 32.1 ± 23.5 months, and mean number of injections was 31.3 ± 24.2. Mean VA was 0.26 ± 0.21 logMAR (Snellen 20/36) at baseline versus 0.20 ± 0.23 logMAR (Snellen 20/32) at the end of the follow-up (P = 0.28). All eyes presented with sub-foveal, type 1 macular neovascularization (MNV). Average sub-foveal choroidal thickness changed from 189.70 ± 68.46 μm at baseline to 169.00 ± 63.06 μm (P < 0.001) at last follow-up.

CONCLUSION

Patients with type 1 NV-AMD, irregular PED, and non-resolving SRF and under continuous treatment of monthly anti-VEGF injections may maintain good visual acuity after long period of time.

Intravitreal Conbercept Injection as an Adjuvant in Vitrectomy with Silicone Oil Infusion for Severe Proliferative Diabetic Retinopathy

Purpose: To assess the clinical effects of preoperative, intraoperative, or preoperative combined with intraoperative intravitreal conbercept (IVC) injection in vitrectomy with silicone oil tamponade for severe proliferative diabetic retinopathy (PDR). Methods: Ninety-eight eyes of 98 severe PDR patients undergoing vitrectomy with silicone oil tamponade were randomly assigned to 3 groups: Group 1 (34 eyes) received IVC injections 3 to 5 days before surgery; Group 2 (35 eyes) received IVC injections at the end of surgery; and Group 3 (29 eyes) received IVC injections 3 to 5 days before and at the end of operation. Follow-up examinations were performed for 6 months. Results: The incidence and severity of intraoperative bleeding were not significantly different (P = 0.233). However, the duration of surgery was significantly shorter in Group 1 and Group 3 compared with Group 2 (P < 0.001). The incidences of early and late recurrent vitreous hemorrhage (VH) were 32.35%, 28.57%, and 13.80%, respectively. At 6-month follow-up, mean best-corrected visual acuity had significantly increased to 1.25 ± 0.45 logMAR in Group 1, 1.29 ± 0.46 logMAR in Group 2, 1.16 ± 0.44 logMAR in Group 3 (all P < 0.001). The incidence of postoperative VH, neovascular glaucoma, and retinal detachment in Group 3 was slightly lower, however, no significant differences were observed (all P > 0.05). In young patients, similar results were observed and Group 3 had better visual improvements (P = 0.037). Conclusions: Preoperative IVC injection could be a safe and effective adjunct in pars plana vitrectomy with silicone oil tamponade for severe PDR. Preoperative combined with intraoperative IVC are promising, especially in young patients.

Nonresponders to Ranibizumab Anti-VEGF Treatment Are Actually Short-term Responders: A Prospective Spectral-Domain OCT Study

PURPOSE

To investigate the inter-individual variability in duration of anti-vascular endothelial growth factor (VEGF) treatment effect in neovascular age-related macular degeneration (nvAMD).

DESIGN

Prospective observational multi-centered study.

PARTICIPANTS

Forty-eight patients with nvAMD treated with anti-VEGF injections were included. Both treatment naive (n=25) as well as patients who had previously received treatment with ranibizumab (n=23) more than one month prior to their enrollment were recruited.

METHODS

Patients received injection with ranibizumab (0.5 mg/0.05 ml) and were followed weekly for 4 weeks with spectral-domain OCT (SD-OCT) assessing the time to maximal reduction of central retinal thickness (CRT) and the presence of intraretinal and subretinal fluid. Other data collected included age, gender, visual acuity, axial length, lens status, and previous injections. The Shapiro-Wilk test was used to examine normal distributions for all variables. Correlations were examined by calculating Spearman's correlation coeficient. Distributions of quantitative variables are described as means (±SD). Qualitative variables are summarized by counts and percentage.

MAIN OUTCOME MEASURES

Time to maximal reduction of CRT and intra- and subretinal fluid after ranibizumab injection.

RESULTS

A total of 48 eyes of 48 patients (age 74.8±8.3 years, 62.5% female, 52% treatment naive, 35.4% pseudophakic) were assessed. Two-thirds (64.6%) reached maximal CRT reduction earlier than the standard 4-week interval: 6.3% at 1 week postinjection, 22.9% at 2 weeks postinjection, and 35.4% at 3 weeks postinjection. Only 35.4% of patients had maximal CRT reduction at 4 weeks. Twenty percent of treatment-naive and 34.8% of non-naive patients had a week-4 CRT that was >35 μm thicker than the earlier occuring lowest CRT value (nadir). The time to maximal CRT reduction was not related to axial length, age, lens status, or history of injections.

CONCLUSIONS

Optimal dosing interval for maximal CRT reduction may be less than 4 weeks for a significant proportion of patients. Most patients will be classified as complete responders if intervals less than 4 weeks are used to assess anti-VEGF treatment response. Disease load rather than eye size appears to be the driver of anti-VEGF treatment duration and therefore, dosing interval needs to be optimized in the cohort of short-term responders.