What is Plasminogen Deficiency?
The most common and visible lesion associated with plasminogen deficiency is ligneous conjunctivitis, which is characterized by thick, woody (ligneous) growths on the conjunctiva of the eye, and if left untreated, can lead to corneal damage and blindness. Ligneous growths tend to recur after surgical excision, thereby requiring multiple surgeries.
While ligneous conjunctivitis is the best characterized and visible lesion, congenital plasminogen deficiency is a multi-systemic disease that can also affect the ears, sinuses, tracheobronchial tree, genitourinary tract, and gingiva. Tracheobronchial lesions including hyper viscous secretions can result in respiratory failure. Hydrocephalus has also been reported in children with severe hypoplasminogenemia, apparently related to the deposition of fibrin in the cerebral ventricular system.
Patients may be born with the inability to produce sufficient plasminogen naturally, a condition referred to as congenital plasminogen deficiency or suffer an acute or acquired deficiency following a trauma or an illness. While our first priority is to provide the treatment of congenital plasminogen deficiency, the Corporation intends to further expand the clinical uses of plasminogen as a priority over the coming years.
Prometic has been working on pursuing new indications such as the treatment of wounds such as diabetic foot ulcers and tympanic repair, acquired plasminogen deficiency in critical care such as severe burns and acute lung injury (“ALI”). The expansion of the plasminogen development program enables the Corporation to target multiple clinical indications with unmet medical needs and leverage the same proprietary Active Pharmaceutical Ingredient (“API”) via different formulations and presentations.
Clinical Trial Information for Treatment of Congenital Plasminogen Deficiency
In a phase 2/3 clinical trial for the treatment of congenital plasminogen deficiency, Ryplazim™ (plasminogen) met its primary and secondary endpoints following the intravenous administration of Ryplazim™ (plasminogen) to patients. In addition to being well tolerated and without any drug related serious adverse events, our Ryplazim™ (plasminogen) treatment achieved a 100% success rate of its primary end point, namely, a targeted increase in the blood plasma concentration level of plasminogen as a surrogate target. Moreover, all patients who had active visible lesions when enrolled in the trial had complete healing of their lesions within weeks of treatment – a 100% patient response rate for this secondary end point.
New long term clinical data was disclosed in July 2017 from the pivotal phase 2/3 trial of Ryplazim™ (plasminogen) regarding the additional 36 weeks treatment period. The new data demonstrated that its plasminogen treatment prevented the recurrence of lesions in the 10 patients treated with Ryplazim™ (plasminogen) for a total of 48 weeks.
The current BLA filing includes the clinical data on 10 patients with 12 weeks of data for an accelerated regulatory pathway. Since filing the current BLA, Prometic has accumulated additional clinical data encompassing more than 3,200 infusions of Ryplazim™ (plasminogen) over treatment periods exceeding 48 weeks during which similar clinical activity and tolerability profiles, as previously reported, were observed. The original guidance from the FDA was for Prometic to submit such long-term clinical data in a supplemental BLA in order to secure full licensure in 2019. Full licensure would provide for the long-term efficacy and safety data to be included in the prescribing information of Ryplazim™ (plasminogen) which would further support Prometic’s claims of the strong health economics benefit associated with the use of Ryplazim™ (plasminogen). The company continues to supply Ryplazim™, to those patients enrolled in the original clinical trials.
The FDA’s review of the BLA raised no issues regarding the clinical data for the accelerated approval. The FDA has, however, identified the need for Prometic to make a number of changes in the Chemistry, Manufacturing and Controls (CMC) section of its BLA. These changes require the implementation and validation of additional analytical assays and “in-process controls” in the manufacturing process of Ryplazim™ (plasminogen). It will be necessary to manufacture additional Ryplazim™ (plasminogen) lots to support the implementation and validation of these process changes.
The FDA requested that such CMC data be submitted as an amendment to the current BLA and has invited Prometic to also submit the long-term (48-week) clinical data at the same time instead of through the originally agreed upon supplemental BLA process. This will allow the FDA to consider granting full-licensure under the current BLA. If granted, this is expected to allow a faster sales ramp-up from launch than could have been achieved had provisional licensure been obtained by the current PDUFA date.
The FDA indicated that the submission of the new CMC data will not impact the previously granted designations, including the Priority Review Status, the Orphan Drug Designation and the Rare Pediatric Disease Designation for Ryplazim™ (plasminogen) for the treatment of congenital plasminogen deficiency.
The Company continues to interact with the FDA regarding the filing of its BLA amendment. It has also engaged external consultants to assist with this, and will provide further updates as to timelines in due course.