The End of Intravitreal Injections?

Intravitreal injection of drugs is now the standard of care for treatment of many forms of diabetic macular edema and “wet” macular degeneration. The results after injection can be amazing, yet every time I inject a patient, I am acutely aware that there is a small risk of developing endophthalmitis with the injection – 1/1000 per injection. And as is often the case, the organisms causing infection with intravitreal injections often lead to loss of vision. It’s a small risk, but a very real one. I wish there were some way to deliver the drugs without having to inject them into the vitreous.

So, I was excited to read of the study by Patel et al from the Georgia Institute of Technology that was published in the July 2012 issue of Ophthalmology and Visual Science. They describe using a 750 micron needle to inject drugs into the suprachoroidal space (SCS) of rabbit eyes. This technique delivers drugs to the chorioretinal area, through the sclera, and avoids entering the vitreous cavity. Presumably, the risk of endophthalmitis would be greatly reduced, if not eliminated, with this technique.

750 micron needle used for suprachoroidal injections (Courtesy of Medscape)

The study showed that drug concentrations after such injections were higher in the posterior segment of the eye than the anterior segment, and that they stayed around longer than with intravitreal injections.

Of course, the efficacy of this technique would need to be proven in humans, and I look forward such studies. I’m thrilled that such work is being done as it could help reduce the main concern of intravitreal injection, endophthalmitis.

If you are Medscape member, you can read more about the study here.  Microneedle Developed for Back-of-the-Eye Injections

CATT Results Released: Avastin and Lucentis Equivalent for AMD

Well, it’s the big news today. The one-year results of the NIH sponsored CATT trial, comparing Avastin (bevacizumab) and Lucentis (ranibizumab) in a head-to-head comparison for the treatment of AMD were released early. The results at one year show equal efficacy in terms of visual acuity. Interestingly, the study also show that prn dosing results in equal visual acuities when compared to monthly dosing.

Here are the key paragraphs from the NIH press release. The full article is available online at the NEJM site, if you have access to that site.

“NEI launched CATT in 2008 to compare Lucentis and Avastin for treatment of wet AMD. The study has now reported results for 1,185 patients treated at 43 clinical centers in the United States. Patients were randomly assigned and treated with one of four regimens for a year. They received Lucentis monthly or PRN, or Avastin monthly or PRN. Enrollment criteria required that study participants had active disease.

“Patients in the monthly dosing groups received an initial treatment and then had an injection every 28 days. Patients in the PRN groups received an initial treatment and were then examined every 28 days to determine medical need for additional treatment. PRN groups received subsequent treatment when there were signs of disease activity, such as fluid in the retina. Ophthalmologists involved in patient care did not know which study drug a patient was getting, to make sure that the data was not affected by how anyone felt about the treatment.

“Change in visual acuity served as the primary outcome measure for CATT. Thus far, visual acuity improvement was virtually identical (within one letter difference on an eye chart) for either drug when given monthly. In addition, no difference was found in the percentage of patients who had an important gain or loss in visual function. Also, when each drug was given on a PRN schedule, there also was no difference (within one letter) between drugs. PRN dosing required four to five fewer injections per year than monthly treatment. Visual gains were about two letters less with PRN than with monthly treatment but overall visual results were still excellent.

“‘In addition to the primary finding of equivalence between Lucentis and Avastin for visual acuity, CATT also demonstrates that PRN dosing is a viable treatment option for either of these drugs,’ said Daniel F. Martin M.D., study chair for CATT and chairman of the Cole Eye Institute at the Cleveland Clinic. ‘Substantial visual acuity gains may be accomplished with a lower treatment burden.’

“Adverse events indicate development or worsening of a medical condition. They may or may not be causally associated with the clinical trial treatment, but they are always monitored and reported in any clinical trial. The median age of patients in CATT was over 80 years, and a high rate of hospitalizations might be anticipated as a result of chronic or acute medical conditions more common to older populations.

“Serious adverse events (primarily hospitalizations) occurred at a 24 percent rate for patients receiving Avastin and a 19 percent rate for patients receiving Lucentis. These events were distributed across many different conditions, most of which were not associated with Avastin in cancer clinical trials where the drug was administered at 500 times the dose used for AMD. The number of deaths, heart attacks, and strokes were low and similar for both drugs during the study. CATT was not capable of determining whether there is an association between a particular adverse event and treatment. Differences in serious adverse event rates require further study.

“Investigators in the CATT study will continue to follow patients through a second year of treatment. These additional data will provide information on longer-term effects of the drugs on vision and safety.

Lucentis vs Avastin: Who will win the race?

As we await the results of the NIH sponsored CATT trial, a head-to-head comparison of ranibizumab (Lucentis) and bevacizumab (Avastin), other smaller studies are trickling in, pointing to what many of us suspect from clinical experience — their efficacy is pretty much the same. Fong et al. published a study in the February issue of Ophthalmology (Intravitreal bevacizumab and renibizumab for age-related macular degeneration) which compared the results from 342 pateints treated with bevacizumab and 128 with ranibiumab. It was a non-randomized trial and the bevacizumab patients were younger. The study showed that both groups had fairly equal results at 12 months. About 23% of bevacizumab patients and 25% of ranibizumab patients had visual acuity of 20/40 or better. More patients with bevacizumab (27%) had improved vision compared to ranibizumab (20%). So, I think we can call it close to even, and remember that about 25% will have improvement of vision and the same percentage with get to 20/40 or better.

The one point that stood out was that in a year, the bevacizumab patients needed about 4 injections, whereas the ranibizumab patients needed 6 injections. This is in keeping with the thought that bevacizumab, being a larger molecule, stays around longer and has a longer duration of action.

Which brings us to the road ahead. The fact that the CATT study has not been stopped, points to the fact that bevacizumab is likely not either significantly less effective or more dangerous than its $2000 per dose cousin, ranibizumab. Both drugs are made by Genentech, bevacizumab being the off-label one. It’s tough for a company to have two of its drugs competing against one another, especially if the off-label one wins or comes close to being even. I believe that Genentech’s approach in the coming years will be to make ranibizumab easier to use. The concern with both these drugs is the ongoing burden of repeat injections. We have a history of the development of sustained-release intraocular drugs in ophthalmology, and the next step is to get one of these drugs into a sustained release form to decrease the number of injections required. Genentech will develop ranibizumab in a sustained release form, leaving bevacizumab to be injected repeatedly. So the issue of equal efficacy will become moot.

Bilateral same-day intravitreal injections? Yes!

One of the growing issues in treating age-related macular degeneration (AMD) is to reduce the burden of treatment for the patients, many of whom are elderly, and may require injections of VEGF inhibitors every 4-8 weeks. A long-standing tradition in ophthalmology has been to avoid bilateral same-day surgical intervention. The rationale has been that if you operate on two eyes on the same day, any infection that develops in one eye may spread to the other eye, and that if there is any contamination of instruments or compounds used during the surgery, operating on both eyes on the same day increases the likelihood that both eyes will be adversely affected.

Intravitreal injections, which have become standard of care for treatment of AMD are fairly innocuous in terms of surgical insult. The “wound” is a 31 gauge needle entry site. Nevertheless, endophthalmitis may develop. For example, in the VISION study of intravitreal pegaptanib, the incidence of endophthalmitis was 0.16%. In the MARINA study of intravitreal ranibizumab, it was 0.05%. And in the ANCHOR study of ranibizumab, it was 0.05% (3 cases our of 5,921 injections). A study by Pilli et all reported an incidence of 0.029% (3 cases in 10,254 injections). These incidences were for unilateral injections.

So, is there an increased risk for bilateral same-day injections? Lima et al (Yannuzzi’s group) out of New York published their retrospective analysis of bilateral same-day intravitreal injections of VEGF inhibitors in the October 2009 issue of Retina. They report that of 1,534 bilateral injections (3,068 injections total), the incidence of culture-proven endophthalmitis was 0.065%, and the incidence of acute intraocular inflmaation was 0.033%. None of those cases were bilateral. There were no cases of retinal breaks. They conclude that it appears that there is no increased risk for same-day bilateral injections of VEGF inhibitors, as the complication rates are similar.

It’s noteworthy that all patients in their study were done in the office, and received surface disinfection with 5% providone-iodine solution, followed by 2 days of either polytrim or ofloxacin qid.

The study is very useful and gives comfort to those of us considering bilateral same-day injections. In any disease process where the incidence of an occurence is very low, large numbers of patients are needed to determine whether or not there is a difference in incidence between groups, and so, it is fair to say that there is no obvious increase in the risk of complications from bilateral VEGF inhibitor injections, while recognizing the limitation of the comparison.

Bevacizumab helpful in BRVO

The SCORE study showed that intravitreal triamcinolone was no more helpful than standard therapy (macular laser) in improving vision in patients with branch retinal vein occlusions (BRVO), and thus the SCORE study concluded to continue using standard therapy to treat BRVO.  The question is, might another agent, say a VEGF inhibitor like bevacizumab (Avastin) be helpful in treating BRVO?

We get some indirect answers in a study published in the November/December issue of Retina.  The study (Comparison of two doses of intravitereal bevacizumab as primary treatment for macular edema secondary to branch retinal vein occlusion:  results of the pan american collaborative retina study group at 24 months) by Wu et al and the Pan-American Collaborative Retina Study Group was a retrtospective multicenter study looking at results from 63 eyes treated with two different doses of bevacizumab:  1.25 mg and 2.5 mg.  Other studies had shown benefit in visual acuity and central macular thickness (CMT) with bevacizumab in BRVO, and the authors wondered if an increased dose may improve the visual outcome or decrease the frequency of injections.  Patients with macular edema were given bevacizumab at one of the two doses (depending on the center they visited) and were examined on a monthly basis.  OCT’s were performed at months 1, 3, 6, 12 and 24.  If at any time the OCT measured CMT > 250 microns, they were classified as “recurrent” or “persistent” macular edema, and were re-injected.  Re-injections were also given if visual acuity decreased by more than 5 letters (1 line).

Their study found that there was no additional benefit from the higher dose, and that both groups experienced improved vision and decreased CMT.  The results showed that on average, CMT improved from about 450 mic at the first visit, to 250 mic at 3 months, and ended up at the 240 mic range at 24 months.  Furthermore, the mean time for repeat injections was in the 10-13 week range.

But is this better than laser?  Well, the study doesn’t directly look at this question, but it does state that among its small sample size of 63 eyes, of those receiving 1.25 mg, 68% experienced improvement in vision by 3 or more lines of vision (72% in the 2.5 mg group).  That’s pretty significant percentage of improved vision.  You’ll recall that the SCORE Study patients had improved vision in the 26-29% range for IVTA and laser.  So bevacizumab seems to give better results than laser for BRVO.  I realize I’m mixing studies — not really a meta-analysis (maybe a “mini”-analysis), and clearly this needs to be studied further.  But the authors seem to lay out a reasonable approach for treating BRVO with bevacizumab, and their results seem to be significantly better than best results we have available with laser or IVTA.  Check vision monthly, and if worse by 5 letters, treat with bevacizumab;  check OCT at 3, 6 12 and 24 mo, and if CMT > 250 treat with bevacizumab.  Expect about 70% to improve 3 or more lines of vision.

Is Avastin the new laser for diabetic macular edema?

In the June 2009 issue of Ophthalmology Soheilian et al, out of Tehran, published an important paper comparing intravitreal bevacizumab (IVB) alone or in combination with triamcinolone (+IVTA) to macular photocoagulation for treatment of diabetic macular edema.  They randomized a total of 150 eyes with clinically significant macular edema (CSME) into three treatment groups, and followed them for up to 36 weeks (which is about 9 months).   If CSME persisted at 12 week (3 mo) intervals, the eye were retreated with the same intervention.  Their study showed that intravitreal bevacizumab yielded better visual acuity results at 36 weeks than did laser treatment.  Specifically, vision improved by > 2 Snellen lines of acuity in 37% of the IVB group, 25% of the IVB+IVTA group, and 15% of the laser group.  On the other hand, retreatment was required in 28%, 20% and 6% of the three groups respectively.  IVB improves vision more, but needs to be used more often.

One of the things that the study did not do, was differentiate the patients with CSME into those with cystic edema and those with non-cystic edema.  My hunch is that we would find that in the group with cystic edema, the difference between the effectiveness in bevacizumab and laser would be even greater.  Will bevacizumab become a replacement for laser in treating CSME?  It’s too soon to say.  My hope is that the Sohelian et al will continue to follow these patients and report on results as they reach the 1 year and 2 year marks.

In clinical practice, this paper seems to support what many of us are currently doing:  using bevacizumab as first line treatment for diabetic macular edema to decrease the edema and improve the vision, and following it up with laser treatment for long term control.  I’d like to see a study that looks at this situation.  I use the sequential approach with greatest success in patients with massive or cystic macular edema.

Here is the abstract:

Ophthalmology. 2009 Jun;116(6):1142-50. Epub 2009 Apr 19.

Randomized trial of intravitreal bevacizumab alone or combined with triamcinolone versus macular photocoagulation in diabetic macular edema.

Soheilian M, Ramezani A, Obudi A, Bijanzadeh B, Salehipour M, Yaseri M, Ahmadieh H, Dehghan MH, Azarmina M, Moradian S, Peyman GA.

Ophthalmology Department, Labbafinejad Medical Center, Shaheed Beheshti Medical University, Tehran, Iran. masoud_soheilian@yahoo.com

PURPOSE: To compare the results of intravitreal bevacizumab (IVB) injection alone or in combination with intravitreal triamcinolone acetonide (IVT) versus macular laser photocoagulation (MPC) as a primary treatment of diabetic macular edema (DME). DESIGN: Randomized 3-arm clinical trial. PARTICIPANTS: A total of 150 eyes of 129 patients with clinically significant DME and no previous treatment.

METHODS: The eyes were randomly assigned to 1 of the 3 study arms: the IVB group, patients who received 1.25 mg IVB (50 eyes); the IVB/IVT group, patients who received 1.25 mg of IVB and 2 mg of IVT (50 eyes); and the MPC group, patients who underwent focal or modified grid laser (50 eyes). Retreatment was performed at 12-week intervals whenever indicated. MAIN OUTCOME MEASURES: Change in best-corrected visual acuity (VA) at week 24.

RESULTS: VA changes among the groups were statistically significant at 6 (P<0.001) and 24 (P = 0.012) weeks. The significant treatment effect was demonstrated in the IVB group at all follow-up visits and in the IVB/IVT group at 6 and 12 weeks. VA changes +/- standard deviation at 36 weeks were -0.28+/-0.25, -0.04+/-0.33, and +0.01+/-0.27 logarithm of minimum angle of resolution in the IVB, IVB/IVT, and MPC groups, respectively (P = 0.053). Significant central macular thickness (CMT) reduction was observed in all groups only up to 6 weeks; however, CMT changes were not significant among the groups in all visits. Overall, retreatment was required for 27 eyes up to 36 weeks (14 in the IVB group, 10 in the IVB/IVT group, and 3 in the MPC group). In the IVB group, in which a greater VA improvement was observed, only 1 injection was required in 72% of the cases. VA improvement >2 Snellen lines at 36 weeks was detected in 37%, 25%, and 14.8% of patients in the IVB, IVB/IVT, and MPC groups, respectively.

CONCLUSIONS: Intravitreal bevacizumab injection in patients with DME yielded a better visual outcome at 24 weeks compared with macular photocoagulation. A change in CMT beyond the 6-week time point that corresponded to the vision change was not detected. No adjunctive effect of IVT was demonstrated.

Bevacizumab speeds resolution of vitreous hemorrhage

A study in the September 2009 issue of Retina by Huang et al. out of Taiwan is titled “Intravitreal Bevacizumab and Panretinal Photocoagulation for Proliferative Diabetic Retinopathy Associated with Vitreous Hemorrhage.”  In this important study, they took 40 patients with vitreous hemorrhage (VH) too dense to treat with PRP, and if the VH  did not clear within two weeks, they treated them with bevacizumab (Avastin).  If the VH did not clear, they treated again in 4-6 weeks.  If the VH heme had not cleared by 12 weeks, they performed a pars plana vitrectomy (PPV).  They compared this to a group of 40 patients who did not receive bevacizumab.  When the vitreous was clear enough in either group, they received PRP.

The results showed that patients receiving bevacizumab cleared anywhere from 2-20 weeks (avg 12 weeks), whereas the patients who did not receive bevacizumab required 6-30 weeks (avg 18 weeks) to clear.  Only 10% of those receiving bevacizumab required PPV, whereas 40% of those who did not receive the drug required PPV.

So, clearly, intravitreal bevacizumab is helpful in the initial treatment of VH from proliferative diabetic retinopathy.  It improves the rate of resolution of VH, and decreases the need for surgery.  Two points were of interest to me.  Neither was specifically studied in the paper, but the authors raise the issues in their study design .  First, they remind us that bevacizumab can induce a fibrous response (“Avastin crunch”) and lead to tractional retinal detachments, and so they excluded patients whose ultrasounds showed the presence of tractional detachments or fibrous responses.  They repeated the B-scans as they followed the injected patients to watch for tractional detachments.  Second, they chose 4-6 weeks as the interval for re-injection of bevacizumab. They based this on two previous papers.  One by Jorge et al. which showed that peak regression of NV in diabetic retinopathy occured at 6 weeks, and that by 12 weeks, leakage had resumed; and the other by Arevalo et al. which showed that regression of NV could occur as quickly as 7-15 days after injection of bevacizumab.

Pearls to take away:  Inject bevacizumab for dense vitreous hemorrhages, get a baseline B-scan and follow the B-scans after injection for tractional detachments, and consider re-injections at 4-6 weeks.