Profile of ocriplasmin and its potential in the treatment of vitreomacular adhesion

Mutational Analysis of Ocriplasmin to Reduce Proteolytic and Autolytic Activity in Pichia pastoris

BACKGROUND

Ocriplasmin (Jetrea) is using for the treatment of symptomatic vitreomacular adhesion. This enzyme undergoes rapid inactivation and limited activity duration as a result of its autolytic nature after injection within the eye. Moreover, the proteolytic activity can cause photoreceptor damage, which may result in visual impairment in more serious cases.

RESULTS

The present research aimed to reduce the disadvantages of ocriplasmin using site-directed mutagenesis. To reduce the autolytic activity of ocriplasmin in the first variant, lysine 156 changed to glutamic acid and, in the second variant for the proteolytic activity reduction, alanine 59 mutated to threonine. The third variant contained both mutations. Expression of wild type and three mutant variants of ocriplasmin constructs were done in the Pichia pastoris expression system. The mutant variants were analyzed in silico and in vitro and compared to the wild type. The kinetic parameters of ocriplasmin variants showed both variants with K156E substitution were more resistant to autolytic degradation than wild-type. These variants also exhibited reduced Kcat and Vmax values. An increase in their Km values, leading to a decreased catalytic efficiency (the Kcat/Km ratio) of autolytic and mixed variants. Moreover, in the variant with A59T mutation, Kcat and Vmax values have reduced compared to wild type. The mix variants showed the most increase in Km value (almost 2-fold) as well as reduced enzymatic affinity to the substrate. Thus, the results indicated that combined mutations at the ocriplasmin sequence were more effective compared with single mutations.

CONCLUSIONS

The results indicated such variants represent valuable tools for the investigation of therapeutic strategies aiming at the non-surgical resolution of vitreomacular adhesion.

ASSESSMENT OF ANATOMICAL AND FUNCTIONAL OUTCOMES WITH OCRIPLASMIN TREATMENT IN PATIENTS WITH VITREOMACULAR TRACTION WITH OR WITHOUT MACULAR HOLES: Results of OVIID-1 Trial

Enzymatic vitreolysis with ocriplasmin is more effective in patients with focal vitreomacular adhesion without epiretinal membrane and macular hole ≤400 µm (if present) at baseline. This study shows that the treatment outcomes are related to patient selection.

Purpose:

To evaluate the anatomical and functional outcomes with ocriplasmin in patients with vitreomacular traction (VMT) with or without macular hole (MH).

Methods:

In a Phase 4, multicenter, single-arm, open-label study, eligible patients (VMT with focal adhesion, without epiretinal membrane, and with MH ≤400 µm [if present]) received a single intravitreal injection of ocriplasmin. Nonsurgical resolution of VMT (Day 28 [primary endpoint]), best-corrected visual acuity, MH closure, vitrectomy rate, and safety were assessed through Day 180.

Results:

Overall, 466 patients were included in the full analysis set, of whom 47.4% had VMT resolution by Day 28; resolution rates in patients with VMT without MH, VMT with MH ≤250 µm, and VMT with MH >250 to ≤400 µm were 43.4%, 68.6%, and 62.7%, respectively. Macular hole closure was higher in eyes with VMT and MH ≤250 µm (57.1%) than in eyes with VMT and MH >250 to ≤400 µm (27.5%) at Day 28. Overall, 30.8% of patients with VMT resolution gained ≥10 letters in best-corrected visual acuity at Day 180. Adverse events were consistent with the known safety profile of ocriplasmin.

Conclusion:

Ocriplasmin is effective for resolution of VMT without or with MH (≤400 μm); treatment outcomes can be optimized with patient selection.

PNEUMATIC VITREOLYSIS FOR RELIEF OF VITREOMACULAR TRACTION

Pneumatic vitreolysis with C₃F₈ gas is effective in releasing focal vitreomacular traction in a high percentage of eyes with few adverse events, especially with limited vitreomacular traction (within 1 disk area), lack of thick cellophane membranes, no diabetes mellitus, younger age (mean age of 69.1 years vs. 78.1 years), better baseline best spectacle–corrected visual acuity (mean of 20/50 vs. 20/66), small Stage 2 macular hole, and female gender.

Purpose:

To evaluate the outcome of perfluoropropane (C₃F₈) gas injection for symptomatic vitreomacular traction (VMT) with or without Stage 2 macular hole (MH).

Methods:

A retrospective review of eyes with VMT treated with 0.3 mL of C₃F₈ gas was performed. Patients avoided the supine position until gas resolution. Patients with small MH maintained partial face-down positioning.

Results:

Forty-nine consecutive patients (50 eyes) with symptomatic VMT underwent pneumatic vitreolysis between 2010 and 2016. A posterior vitreous detachment developed in 43 eyes (86.0%) after a single gas injection, at a median of 3.0 weeks. Twenty-eight of 35 eyes (80.0%) with VMT only and all 15 eyes (100%) with a small Stage 2 MH developed a posterior vitreous detachment, with MH closure in 10 of 15 eyes (66.7%). Median baseline and last best spectacle–corrected visual acuities were 20/50 and 20/40, respectively (P < 0.001). Mean follow-up time was 11.1 ± 9.9 months. Rate of posterior vitreous detachment was reduced with presence of diabetes mellitus (25%) and with thick cellophane membrane (50%). Univariate analysis showed increased VMT release for eyes with VMT extent within 1 disk area (χ² = 13.1, P = 0.002), eyes with absence of diabetes mellitus (χ² = 8.8, P = 0.007), and eyes with Stage 2 MH (χ² = 5.47, P = 0.019); there was a trend between success and lack of thick cellophane membrane (χ² = 3.32, P = 0.068). Results using logistic regression also showed younger age (P = 0.012), followed by better baseline best spectacle–corrected visual acuity (P = 0.044), lack of diabetes mellitus (P = 0.077), and female gender (P = 0.045) to be predictors of increased VMT release. One VMT-only eye formed a MH and another VMT-only eye developed a retinal detachment. Both eyes responded to vitrectomy.

Conclusion:

Pneumatic vitreolysis with limited face-down position is a viable option for treating VMT with few adverse events. More studies are needed to elucidate its indications, benefits, and risks.

Special considerations for pediatric vitreoretinal surgery

In this review, the authors present special considerations a vitreoretinal surgeon should take into account before embarking on surgery in a pediatric eye. First, the anatomy of a pediatric eye is different from an adult and changes as the child grows. This is important especially in relation to the placement of transconjunctival ports. The structural characteristics of the sclera are also different, with lower scleral rigidity found in pediatric eyes. When considering vitrectomy, a posterior pars plicata lens-sparing technique should be considered. However, this may not be possible in complicated total detachments where anterior translimbal vitrectomy may be the method of choice. Scleral buckles are preferred for certain cases, and division of the encirclage is advocated in children below the age of 2 years, once the retina has stabilized. Enzymatic vitreolysis has been described as a preoperative adjunct to enhance complete detachment of the posterior hyaloid and reduce iatrogenic retinal breaks. However, its use in pediatric eyes has been limited, and larger studies are warranted. Finally, postoperative visual rehabilitation and treatment of amblyopia are key to maximizing functional outcomes in the pediatric patient. Co-management with a pediatric ophthalmologist and enlisting the co-operation of the parents are essential.

Cyclic stretch induced-retinal pigment epithelial cell apoptosis and cytokine changes

Background

The pathogenesis of age-related macular degeneration (AMD) is complex. It has been shown that vitreomacular traction (VMT) plays a role in the pathogenesis of AMD. We speculate that the continuous stretch induced by VMT might impair the function of retinal pigment epithelium (RPE) cells and it might also be involved in the progression of AMD.

Methods

Cultured ARPE-19 cells were subjected to cyclic stretch on the Flexcell Strain system at a level of 25% increment on the surface area for 8 h, 14 h, 20 h, 24 h. In another group, the stretch was withdrawn at 14 h and the cell cultured for another 6 h. Then, we observed the changes in morphology, apoptosis and expression of interleukin 6 (IL6) and vascular endothelial growth factor (VEGF) in RPE cells under stretch.

Results

We found that stretch induced the RPE cells to change from a spreading shape into a rounded shape, and that the morphological changes were positively correlated with the duration of the stretch. The expression of pFAK397 and pRac1/cdc42 were elevated in a time-dependent fashion. The stretch resulted in an increase in the apoptosis ratio, with Bcl2, Bax and p53 also showing time-dependent changes. In addition, up-regulation of IL6 and VEGF expression levels was also observed. After withdrawal of the stretch, all of these changes were significantly diminished.

Conclusion

Stretch may induce morphological, cell apoptosis, and up-regulation of cytokines changes in RPE cells, indicating that cyclic stretching may participate in the progression of AMD by impeding the functions of the RPE.

[Pharmaological vitreolysis with ocriplasmin as a treatment option for symptomatic focal vitreomacular traction with or without macular holes (≤400 μm) compared to tranconjunctival vitrectomy]

BACKGROUND

To evaluate the resolution rate in patients with symptomatic vitreomacular traction (VMT) ≤ 1500 μm with or without macular holes ≤ 400 μm after therapy with intravitreal ocriplasmin (Jetrea®) injections in a clinical setting in comparison to transconjunctival vitrectomy.

MATERIALS AND METHODS

We examined 21 eyes of 21 consecutive patients with vitreomacular traction with or without macular holes who underwent intravitreal injection of 0.1 ml ocriplasmin and we retrospectively reviewed 18 eyes of 18 patients with VMT with or without FTMH who underwent 23-gauge vitrectomy.

RESULTS

Vitreomacular traction resolved in 15 of 21 eyes treated with ocriplasmin after 6 month (71 %) compared to 100 % of eyes treated by vitrectomy. Of the 5 eyes that initially presented FTMH with VMT in the ocriplasmin group, 2 were closed 1 month after ocriplasmin treatment. The remaining 3 had vitrectomy and closed thereafter. Best corrected visual acuity was 0.38 ± 0.23 LogMAR at baseline, improving to 0.34 ± 0.24 LogMAR at 6 months after ocriplasmin treatment. Best corrected visual acuity in the vitrectomy group improved from 0.55 ± 0.29 LogMAR before operation to 0.53 ± 0.51 LogMAR 6 months postoperatively. Foveal thickness was 355.95 ± 114.53 μm at baseline, reducing to 277.77 ± 40.26 μm at 6 months after ocriplasmin treatment. Foveal thickness of eyes that underwent vitrectomy was 494.61 ± 126.02 μm at baseline, decreasing to 330.2 ± 88.85 μm 6 months postoperatively.

CONCLUSION

When traction is ≤ 1500 μm, enzymatic vitreolysis with ocriplasmin is a therapeutic option. In the presence of VMT >1500 μm or ERM, surgical treatment with vitrectomy is associated with better outcomes. In small macular holes with VMT and in the absence of ERM, enzymatic vitreolysis with ocriplasmin is an option. In cases of holes >400 μm, or in the absence of evident VMT, or in the presence of ERM, vitrectomy is the first choice.

[Ocriplasmin as a treatment option for symptomatic vitreomacular traction with and without macular hole. First clinical experiences]

PURPOSE

To evaluate the resolution rate in patients with symptomatic vitreomacular traction (≤ 1500 μm) with or without macular holes (≤ 400 μm) after therapy with intravitreal ocriplasmin (Jetrea®) injection in a clinical setting.

METHODS

Until now we have prospectively examined 21 eyes of 21 consecutive patients with symptomatic vitreomacular traction with or without macular holes who underwent intravitreal operative injection of 0.1 ml ocriplasmin. The best corrected visual acuity and high-resolution optical coherence tomography (SD-OCT) ultrastructural parameters were measured before injection and again 1, 3 and 4 months after treatment. The numbers of resolved vitreomacular traction and closed macular holes were documented.

RESULTS

Vitreomacular traction was resolved in 15 out of 21 (71 %) eyes. Of the five eyes which initially presented with vitreomacular traction with macular holes, all showed resolution of vitreomacular traction but only two of the macular holes were closed. The average best corrected visual acuity was 0.38 logMAR (± 0.23) at baseline and 0.43 logMAR (± 0.28), 0.38 logMAR (± 0.27) and 0.36 logMAR (± 0.24) 1, 3 and 4 months after injection, respectively. The average foveal thickness was 355.95 μm (± 114.53 μm) at baseline, reducing to 304.61 μm (± 100.91 μm), 308.00 μm (±76.17 μm) and 277.50 μm (± 26.24 μm) after 1, 3 and 4 months, respectively.

CONCLUSION

In this ongoing study there was a high percentage of resolution of vitreomacular traction (71 %) 1 month after intravitreal operative injection of Jetrea® and closure of two out of five macular holes. This was further associated with stabilization of visual acuity and reduction of foveal thickness. Further investigations are necessary to document the effectiveness of the pharmacological vitreolysis in a clinical setting.

Comparison of Guided and Unguided Ocriplasmin Injection for the Treatment of Vitreomacular Traction: A Preliminary Study

This retrospective quality control study aimed at comparing resolution in patients treated with intravitreal ocriplasmin (IVO) using two injection techniques, classical injection procedure (unguided) and targeted injection using a surgical microscope with a 30-gauge 1-inch needle (guided) for the treatment of focal VMT without macular hole. The two groups presented a statistically significant difference in terms of resolution of VMT within the first month following treatment: 1/7 for the unguided group versus 6/7 for the guided group (p = 0.0291). The majority of the guided group presented an earlier resolution than the single resolved case in the unguided group. The results of this preliminary study indicate that the injection of ocriplasmin closer to the site of VMT results in the resolution in a higher number of cases and that this resolution occurs in a short time interval.

Gas-mediated vitreomacular adhesion release with intravitral ranibizumab injections for exudative age-related macular degeneration

PURPOSE

To evaluate the efficiency of gas-assisted vitreomacular adhesion (VMA) release combined with intravitreal ranibizumab injections for exudative age-related macular degeneration (AMD) patients.

MATERIALS AND METHODS

This prospective, interventional case series included a total of 23 eyes of 22 patients. The eyes were treated with intravitreal injection of 0.3 mL of perfluoropropane (C3F8) gas and concomitant intravitreal ranibizumab injection to stimulate VMA release. After three initial loading injections, additional intravitreal ranibizumab injections were performed pro re nata. Over a 12-month period, monthly examinations were performed for best-corrected visual acuity (BCVA, logMAR; logarithm of the minimum angle resolution), optical coherence tomography, and dilated fundus examinations.

RESULTS

After gas injection, 22 eyes (95.7 %) showed complete VMA release at 1 week. Complete VMA was achieved in all eyes at 2 months after VMA release, without serious ocular adverse events except one patient who developed a retinal tear. Mean BCVA was 0.61 ± 0.37 logMAR (20/81 Snellen equivalents) at baseline and 0.46 ± 0.30 logMAR (20/57 Snellen equivalents) at 12 months (P = 0.135). Mean central macular thickness was 357.9 ± 128.6 μm at baseline and 245.6 ± 60.0 μm at 12 months (P = 0.188). Mean numbers of intravitreal ranibizumab injections were 4.8 ± 2.4 times during 12 months (4 to 8 injections).

CONCLUSION

Gas-assisted VMA release can be used as an efficient alternative for exudative AMD patients with obvious VMA.

Quantitative imaging of enzymatic vitreolysis-induced fiber remodeling

PURPOSE

Collagen fiber remodeling in the vitreous body has been implicated in cases of vitreomacular traction, macular hole, and retinal detachment, and also may occur during pharmacologic vitreolysis. The purpose of this study was to evaluate quantitative polarized light imaging (QPLI) as a tool for studying fiber organization in the vitreous and near the vitreoretinal interface in control and enzymatically perturbed conditions.

METHODS

Fiber alignment was measured in anterior-posterior sections of bovine and porcine vitreous. Additional tests were performed on bovine lenses and nasal-temporal vitreous sections. Effects of proteoglycan degradation on collagen fiber alignment using trypsin and plasmin were assessed at the microstructural level using electron microscopy and at the global level using QPLI.

RESULTS

Control vitreous showed fiber organization patterns consistent with the literature across multiple-length scales, including the global anterior-posterior coursing of vitreous fibers, as well as local fibers parallel to the equatorial vitreoretinal interface and transverse to the posterior interface. Proteoglycan digestion with trypsin or plasmin significantly increased fiber alignment throughout the vitreous (P < 0.01). The largest changes (3×) occurred in the posterior vitreous where fibers are aligned transverse to the posterior vitreoretinal interface (P < 0.01).

CONCLUSIONS

Proteoglycan loss due to enzymatic vitreolysis differentially increases fiber alignment at locations where tractions are most common. We hypothesize that a similar mechanism leads to retinal complications during age-related vitreous degeneration. Structural changes to the entire vitreous body (as opposed to the vitreoretinal interface alone) should be evaluated during preclinical testing of pharmacological vitreolysis candidates.