Protalix (PLX) was up on FDA notice last year on a CRL postponement that its PDUFA review of PRX-102. In the meantime, phase III trials continue to provide more positive results.  

Then, on June 2, the company reported more interim data on its Phase III Balance study, and Protalix came out with this statement:

The initial top-line results show that the lower boundary of the confidence interval for the mean difference between the two treatments was below the non-inferiority margin pre-specified for this interim analysis in the ITT analysis set and above such limit in the PP analysis set. At the time of this analysis, two patients discontinued participation due to treatment emergent adverse events (TEAEs). Of these two patients, one discontinued participation due to a related adverse event.

The potential advantages of PRX-102 over Fabrazyme are two. First, in the frequency of dosing, and second, in immunogenicity. With an enzyme replacement therapy like Fabrazyme, an immune reaction against the enzyme tends to eventually develop. With PRX-102, the formulation of the enzyme is designed to inhibit an immune response, and the data show it. Of 30 patients enrolled, 20 patients remained negative for anti-drug antibodies, and of the 10 patients who were initially positive, four became negative at 12 months.

A Class A meeting with the FDA should be upcoming with regard to the next steps to clear the inspection hurdle that brought the CLR. The timeline for commercial launch now moves to Europe for the first half of 2023. With the FDA timeline delay due to the final inspection of their lab in Isreal the FDA results are important and have increased importance Protalix. With this event upcoming shortly there is a potential for serious movement into the stock price in the next month. 

Protalix shares well in April on a CRL received from the FDA. The CRL made no mention of any data but was most likely a logistics issue as an FDA team could not travel to Israel to inspect Protalix Facilities, but Israel is opening up travel again.

Back at the end of last year, Protalix got a notice from the FDA that its PDUFA date for its flagship candidate PRX-102 was postponed by 3 months to April 27. This was entirely due to Covid-19 travel restrictions and not to do with any of the data submitted for approval of the potential Fabrazyme competitor Protalix is developing. The situation here remains quite unique, in that the company has continued to report still more positive data on PRX-102.

The data from the latest Phase III trial further suggest that the drug has a good chance of eventually being approved and challenging Fabrazyme in the Fabry Disease market. Topline results announced back in February showed that 2 mg/kg of PRX-102 administered intravenously once a month was well tolerated with stable clinical presentation maintained in adult Fabry patients. 

Then, on June 2, the company reported more interim data on its Phase III BALANCE study, and Protalix came out with this statement.

The initial top-line results show that the lower boundary of the confidence interval for the mean difference between the two treatments was below the non-inferiority margin pre-specified for this interim analysis in the ITT analysis set and above such limit in the PP analysis set. At the time of this analysis, two patients discontinued participation due to treatment emergent adverse events (TEAEs). Of these two patients, one discontinued participation due to a related adverse event.

The potential advantages of PRX-102 over Fabrazyme are two. First, in frequency of dosing, and second, in immunogenicity. With an enzyme replacement therapy like Fabrazyme, an immune reaction against the enzyme tends to eventually develop. With PRX-102, the formulation of the enzyme is designed to inhibit an immune response, and the data show it. Of 30 patients enrolled, 20 patients remained negative for anti-drug antibodies and of the 10 patients who were initially positive, four became negative at 12 months.

A Class A meeting with the FDA should be upcoming with regard to the next steps to clear the inspection hurdle that brought the CLR. The timeline for commercial launch is dependent on this and will add upcoming volatility to the stock hopefully with positive signs from the FDA which the market has largely given up on.

Related Articles:
There Is Beta In Protalix Stock Due To PRX-102
Protalix BioTherapeutics Announces FDA Acceptance Of BLA For The Treatment Of Fabry Disease And Grants Priority Review
Protalix BioTherapeutics Pipeline Progress

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