Efficacy and Safety of IncobotulinumtoxinA for the Treatment of Blepharospasm: A Multicenter, Phase 3 Study in Japan

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The study's approach is certainly good and makes sense, but unfortunately, I don't understand the implementation. I appreciate the shortened time intervals, but I'm skeptical about the sample sizes for drawing conclusions about antibodies, etc. The fixed dosage also bothers me. 100 units is a very high dose. Was it truly a fixed dose or a range with a maximum dose of 100 u? A diagram of the dose distribution would be helpful. Several references that I consider important are missing, for example:

Wabbels B, Jost WH, Roggenkämper P. Diffuculties with differentiating botulinum toxin treatment effects in essential blepharospasm. J Neural Transm 2011; 118: 925-943

Author Response

Reviewer 1

Comment: The study's approach is certainly good and makes sense, but unfortunately, I don't understand the implementation. I appreciate the shortened time intervals, but I'm skeptical about the sample sizes for drawing conclusions about antibodies, etc. The fixed dosage also bothers me. 100 units is a very high dose. Was it truly a fixed dose or a range with a maximum dose of 100 U? A diagram of the dose distribution would be helpful. Several references that I consider important are missing, for example:

Wabbels B, Jost WH, Roggenkämper P. Difficulties with differentiating botulinum toxin treatment effects in essential blepharospasm. J Neural Transm 2011; 118: 925-943

Response: Thank you for your comment. Regarding antibodies, as you correctly noted, drawing definitive conclusions is not feasible given the small sample size. As this was presented as a speculative consideration, we have revised the following sentence in the manuscript (Lines 200–203):

 “None of the patients discontinued incobotulinumtoxinA due to a lack of efficacy, which may support the low immunogenicity [14] and sustained efficacy of this botulinum toxin formulation.”

Regarding dosage, the first injection was administered at a fixed dose, as depicted in Figure 5. The dose distribution is summarized in Table S2. As described in Table S2, among the 29 patients,16 received 50 U, 9 received 75 U, and 4 received 100 U as the first injection dose. Among botulinum toxin-naïve patients, 6 received a fixed dose of 50 U. Consequently, 10 patients with prior botulinum toxin treatment received 50 U, 9 received 75 U, and 4 received 100 U. Based on this information, we came to the conclusion that an additional diagram of dose distribution may not be necessary. We appreciate your understanding and consideration.

To provide readers with additional context regarding the use of multiple evaluation scales, we have added the suggested citation to the following sentence in section 5.4 (Lines 329–330):

“The secondary endpoints included JRS severity, frequency, and total scores [27] assessed up to 48 weeks; BSDI score [27]; PEGR score; and results of the fast blinking test.”

Reference 27. Wabbels, B.; Jost, W.H.; Roggenkämper, P. Difficulties with differentiating botulinum toxin treatment effects in essential blepharospasm. J. Neural. Transm. (Vienna) 2011, 118, 925–943. https://doi.org/10.1007/s00702-010-0546-9 

Reviewer 2 Report

Comments and Suggestions for Authors

The paper is written in a concise manner and comprehensively describes patient selection, results, and statistical analysis. Methodologically, the paper constitutes a sound clinical trial. Studies on the use of incobotulinumtoxinA in the treatment of blepharospasm have already been conducted. However, no such studies have been conducted in Asian populations. The authors address certain limitations of the study, related to the small number of patients recruited for the study and the lack of a meaningful comparison with a placebo group. Nevertheless, the paper was prepared with great care, and I recommend the work for publication.

Author Response

Reviewer 2

Comment: The paper is written in a concise manner and comprehensively describes patient selection, results, and statistical analysis. Methodologically, the paper constitutes a sound clinical trial. Studies on the use of incobotulinumtoxinA in the treatment of blepharospasm have already been conducted. However, no such studies have been conducted in Asian populations. The authors address certain limitations of the study, related to the small number of patients recruited for the study and the lack of a meaningful comparison with a placebo group. Nevertheless, the paper was prepared with great care, and I recommend the work for publication.

Response: We sincerely thank you for your thoughtful review and for recommending our manuscript for publication.

Reviewer 3 Report

Comments and Suggestions for Authors

In this paper authors presented results from open-label, single-arm, multicenter, phase 3 study about incobotulinum toxin A in Japanese patients with blepharospasm. 

I have some comments about the study. 

1. Authors did not perform Shapiro-Wilks normality test to decide should use mean or median for statistical data.  

2. This sentence is unclear: "The mean ± SD dose for the first injection cycle was 64.66 ± 18.319 U, with 50 ± 0.0 U in botulinum toxin-naïve patients and 68.48 ± 18.795 U in patients who had previously received botulinum toxin treatment (Table S2)." If patients received  50± 0.0 U how mean dose can be bigger?

3. Authors did not explain injections protocol? Why some patients received more, and some received less injections? Suppose that they gave injections according to lenght of treatment response, but this must be pointed out.

4. Figure 3 is unclear. First bars only show after 3^rd and 6^th weeks, but not baseline. According to bars, 6^th and 7^th injections do not show any change from baseline, while authors comment in text bellow the figure that treatment response is sustained during the whole follow-up period. Similar questions are for figure 4 for first injections without bar for baseline and 7^th injections where there is no difference in the scale results.

5. Figure S1 is unclear. I can not understand how many injections sites patients received

6. Figure S2 is unclear for 6^th and 7^th injection because it again do not show any difference between baseline and week 6.

7. In figure S3 to many dosing intervals for only 29 patients in statistical evaluation. 

Author Response

Reviewer 3

In this paper authors presented results from open-label, single-arm, multicenter, phase 3 study about incobotulinumtoxinA in Japanese patients with blepharospasm. 

I have some comments about the study. 

1. Authors did not perform Shapiro-Wilks normality test to decide should use mean or median for statistical data.  

Response: Thank you for your comment. The decision not to perform the Shapiro-Wilks test was because of the primary analysis being a single verification based on the mean. Based on the prespecified statistical analysis plan, we did not perform additional tests to avoid multiplicity. Furthermore, the central limit theorem suggests that with a sufficiently large sample size, the validity of using the mean is not contingent upon the normality of the data itself. Therefore, we respectfully believe that conducting a normality test is not essential for this analysis. Additionally, the sample size was carefully determined to ensure adequate statistical power at an appropriate significance level, which we consider sufficient to meet the study objectives.

2. This sentence is unclear: "The mean ± SD dose for the first injection cycle was 64.66 ± 18.319 U, with 50 ± 0.0 U in botulinum toxin-naïve patients and 68.48 ± 18.795 U in patients who had previously received botulinum toxin treatment (Table S2)." If patients received  50± 0.0 U how mean dose can be bigger?

Response: Thank you for pointing this out. We have revised the sentence as follows for clarity (Lines 92–95):

“The mean ± SD dose for the first injection cycle was 64.66 ± 18.319 U in all patients, with 50 ± 0.0 U in botulinum toxin-naïve patients and 68.48 ± 18.795 U in patients who had previously received botulinum toxin treatment (Table S2).”

3. Authors did not explain injections protocol? Why some patients received more, and some received less injections? Suppose that they gave injections according to length of treatment response, but this must be pointed out.

Response: Thank you for your comment. Although this information has been mentioned in section 5.1 (Study Design and Overview) as “The incobotulinumtoxinA dose and dosing interval for individual patients at second and later injection cycles were determined by the investigator based on their blepharospasm symptoms,” we acknowledge the need for greater clarity.

Treatment response and duration of effect were considered as determining factors; therefore, the sentence has been revised as follows: (Lines 283–285):

“The incobotulinumtoxinA dose and dosing interval for individual patients at the second and subsequent injection cycles were determined by the investigator based on the patients’ blepharospasm symptoms, including treatment response and the duration of effect.”

4. Figure 3 is unclear. First bars only show after 3^rdand 6^thweeks, but not baseline. According to bars, 6^th and 7^th injections do not show any change from baseline, while authors comment in text below the figure that treatment response is sustained during the whole follow-up period. Similar questions are for figure 4 for first injections without bar for baseline and 7^th injections where there is no difference in the scale results.

Response: Thank you for your comment. Figures 3 and 4 illustrate changes from the baseline of the first injection, where baseline corresponds to 0. In Figure 3, the efficacy at the sixth and seventh injections shows continuous improvements from the first injection baseline. These improvements are evident at the baseline of the sixth injection, 6 weeks after the sixth injection, at the baseline of the seventh injection, and 6 weeks after the seventh injection. Thus, we have concluded that the treatment response was sustained throughout the follow-up period.

The same approach is applicable to the seventh injection shown in Figure 4. At both the baseline of the seventh injection and 6 weeks after the seventh injection, improvements from the baseline of the first injection continued to be evident, indicating that the treatment response was sustained throughout the follow-up period. Based on this, we wish to retain the current description and appreciate your understanding in this regard.

5. Figure S1 is unclear. I cannot understand how many injections sites patients received

Response: Thank you for your comment. Figure S1 illustrates the number of patients who received injections at each injection site during the first injection; however, it does not specify the number of injection sites per patient. There was no predetermined upper limit on the number of injection sites; the selection of muscles and the number of injection sites were also determined by the investigator based on the patient's symptoms. To provide further clarity, we have added the following sentence to the end of the second paragraph of section 5.1 Study Design and Overview (Lines 285–287):

“The selection of muscles and the number of injection sites were also determined by the investigator based on the patients’ blepharospasm symptoms.”

6. Figure S2 is unclear for 6^thand 7^thinjection because it again do not show any difference between baseline and week 6.

Response: Thank you for your comment. Regarding Figure S2, as the reviewer rightly pointed out, there was no observed difference between the baseline at the time of the sixth and seventh injections and the results 6 weeks after administration. This is likely due to the small sample sizes—five patients for the sixth injection and three patients for the seventh—which may have substantially influenced the observed outcomes. Consequently, we believe that these sample sizes are not sufficient to discuss efficacy or other considerations based solely on these findings. For this reason, we have not specifically addressed this point in the manuscript. We appreciate your understanding.

7. In figure S3 to many dosing intervals for only 29 patients in statistical evaluation. 

Response: Thank you for your comment. We assume that this comment pertains to Table S3. Table S3 contains only descriptive statistics and is intended to present readers with the actual distribution of dosing intervals. We appreciate your understanding.