Joao Siffert
Analyst · Jefferies
Thank you, Sofia, and thank you all for joining us today for our third quarter business highlights. I look forward to providing important updates on the progress and status of our gene and cell therapy development programs. On the call today, I'll review our key quarter accomplishments and then turn the call over to Christine to review our financials.
I'd like to start off with an update on our lead and most advanced clinical program for recessive dystrophic epidermolysis bullosa or RDEB. RDEB is a debilitating and rare genetic skin disorder caused by mutations in Collagen VII that lead to defects in the anchoring fibrils, which attach to the dermis to the epidermis of the skin. RDEB patients have extremely fragile skin that blisters and tears, resulting in large wounds that can remain unhealed for years. These wounds can be very debilitating and cover a significant proportion of the patient's body. Today, RDEB patients have no available effective treatment options and are forced to rely on palliative treatments as well as painful, time-consuming and expensive wound care.
Our clinical program for patients with RDEB is developing an autologous gene-corrected cell therapy that restores normal functioning Collagen VII to keratinocytes in their progenitors via a final delivered product called EB-101, which consists of gene-corrected keratinocyte sheets that are transplanted into open wounds.
In September, we announced that we had received a clinical hold letter from the FDA stating that we couldn't begin our planned Phase III trial for EB-101 without submitting additional data relating to transport stability of the EB-101 to clinical sites. I'm pleased to say that we have since submitted to the FDA the additional data related to the transport stability of EB-101, along with the updated clinical protocol and the comparability protocol. These submissions were intended to address the outstanding items listed in our prior disclosures, including the clinical hold. We continue to anticipate that we'll receive CMC clearance in fourth quarter 2019 to move forward with the VIITAL Phase III trial initiation.
As a reminder, the pivotal study will be a multicenter, randomized clinical trial assisting EB-101 -- assessing EB-101 in 10 to 15 RDEB patients with approximately 30 wound sites treated in total. As we have previously discussed, the primary end point of the study will be proportion of wounds with greater than 50% healing at 3 months, comparing treated with untreated wound sites on the same patients. Other end points will include the patient's global impression of change in pain from baseline as well as other patient reported outcomes, such as pain during dressing changes; pain quality and impact, in this case, using the PROMIS scale and the presence of itch, among others.
We believe EB-101 is uniquely positioned to safely provide durable healing for most challenging to treat, large and painful RDEB wounds present in the majority of RDEB patients. In fact, a recent publication from our collaborators at Stanford University School of Medicine highlighted positive long-term data from the Phase I/IIa clinical trial of EB-101. Published in the October issue of the JCI Insight journal, this peer-reviewed article provided additional important data that further bolsters our confidence that EB-101 has the potential to provide sustained, durable healing even in the most challenging wounds.
The results were from 7 patients with 42 treated wounds that had remained open from 3 to 20 years prior to treatment, averaging 11.2 years, highlighting their chronic and intractable nature. 3 years post treatment, the majority of EB-101 treated wounds remained healed and without pain, with 80% of wounds achieving 50% healing and 70% achieving greater or equal to 75% healing. These healing rates correspond to an unparalleled area of healed skin ranging from approximately 130 to 150 centimeter square for most study participants. Study provided additional data to support the clinically meaningful benefit of EB-101 in treating these large chronic wounds, demonstrating that greater than 50% healing, especially in these large wounds, was associated with improvement in pain -- patient reported pain, itch and wound healing and wound durability.
On the molecular level, EB-101 treatment was also associated with long-term expression of Collagen VII, providing mechanism -- mechanistic support of the durability documented clinically for a gene-corrected cell therapy. There have been no treatment-related adverse events reported to date, and no replication-competent virus was detected at any time point.
We couldn't be more pleased with these data and believe EB-101 has the potential to be a transformative treatment in terms of both the extent and the durability of wound healing for patients with RDEB. We look forward to begin the Phase III VIITAL study as soon as possible with hopes to ultimately provide the desperately needed treatment option for RDEB patients.
Moving our focus now over to our MPS IIIA program. MPS IIIA, also known as Sanfilippo syndrome type A, is a rare lysosomal storage disease with no approved treatment that primarily affects the central nervous system or CNS. Currently developing ABO-102 and AAV9 gene therapy, which delivers a functional copy of the SGSH gene to the CNS and peripheral organs via a onetime intravenous infusion are those to correct the underlying deficiency in the SGSH enzyme to prevent the toxic accumulation of heparan sulfate in the cells that ultimately lead to rapid neuro development and physical decline in patients with MPS IIIA.
In July, we announced data from our ongoing 2-year open-label dose escalation Phase I/II global clinical trial for patients with MPS IIIA study, ABT-001. Interim data for the 3 youngest patients enrolled in the highest dose cohort to Cohort 3, ages 26, 19 and 14 months at dosing, suggested that preservation of neurocognitive development could be achieved when MPS IIIA patients were treated during early stages of their disease. We also saw disease-relevant changes in biomarkers with robust and sustained dose-dependent reductions in all 3 cohorts. Combined with a favorable safety profile with no product-related serious adverse events to date, we believe ABO-102 has the potential to help patients to escape the devastating fate of neuro developmental and physical decline typically seen in these patients. We continue to screen patients into the study, and we'll provide an update when additional patients are treated.
On the regulatory front, we remain on track for the FDA and EMA meetings planned in the fourth quarter of this year to discuss our development path forward and expect to provide additional updates when appropriate.
Finally, I'd like to provide a brief update on ABO-101, our investigational gene therapy for the treatment of MPS IIIB, also known as Sanfilippo Syndrome type B. Like the MPS IIIA program -- like MPS IIIA, MPS IIIB is a rare, devastating and fatal lysosomal storage disease with no approved treatment that is characterized by intracellular heparan sulfate accumulation, leading to neuro development decline and other systemic manifestations and early death. We're encouraged by the progress in our 2-year open-label ABT-002 study designed to evaluate 2 doses of ABO-101 with the main objective of assessing safety and neuro developmental progress. Additional secondary end points include changes in CSF and urine heparan sulfate, liver volume and several others.
We have now treated 6 patients across 2 dose cohorts in this study. ABO-101 has been well tolerated to date with no serious drug-related adverse events with up to 23 months of follow-up for the first patient enrolled with a range of 2 to 23 patients -- sorry, 2 to 23 months across the 6 patients. Preliminary data from the trial showed improvement in biomarkers, such as reduction in cerebral spinal fluid heparan sulfate levels and reduction in liver volume of similar magnitude that was observed following ABO-102 administration in patients with MPS IIIA. Enrollment continues across 3 sites in the U.S., Spain and our recently opened site in France.
A brief update on our preclinical pipeline assets where data were presented at the European Society of the Gene and Cell Therapy Congress last month in Barcelona, Spain. Research updates were highlighted in 4 poster presentations featuring our novel AAV capsid library. These updates included data describing improved capsids for increased evasion of neutralizing antibodies against AAV -- natural AAV serotypes, support for intramuscular delivery of gene therapy, for delivery to the retina via intravitreal administration and peripheral nerve system tropism following IV administration in a Pompe disease model.
Looking ahead, we're intensely focused on initiating a VIITAL Phase III trial for RDEB and reporting additional data from our lysosomal storage disorder gene therapies in the coming months. That said, as we approach year-end and the start of a Phase III clinical trial, we'll continue to be judicious and focus our efforts on this and our other lead programs. A review of strategic initiatives with Jefferies remains ongoing, with the goal of advancing the company's mission in maximizing shareholder value and stakeholder value overall.
Before I turn the call over to Christine, I'd like to thank and acknowledge the patients, the families, clinicians, researchers and patient organizations that have made our work possible. We deeply value these partnerships and are committed to finding cures to those patients who most desperately need treatment options.
With that, I'll turn over the call to Christine. Christine?