ITP Press Release
On June 12, 2020, Principia Biopharma Inc. (the “Company”) issued a press release announcing the presentation at a virtual session of the European Hematology Association of positive data on durability of response from its adaptive, open-label, dose-finding Phase 1/2 clinical trial of its proprietary drug candidate, rilzabrutinib, for the treatment of immune thrombocytopenia (ITP).
The analysis presented included 47 heavilypre-treated (median of six prior therapies) adult patients enrolled with a medianfollow-up of 18 weeks. The primary endpoint was the proportion of patients able to achieve two or more consecutive platelet counts, separated by at least five days, of³ 50,000/µL and an increase of platelet count of³20,000/µL from baseline, without use of rescue medication.
Rilzabrutinib treatment at 400 mg twice daily led to both a rapid response detectable at the first platelet measurement (day eight), and a durable response. Fifty percent of patients who started at 400 mg twice daily and had at least 12 weeks of treatment (n=26) achieved the primary endpoint (80 percent confidence interval (CI) 38, 62). In the overall patient population, the primary endpoint was met by 43 percent of patients (80 (CI) 34, 52), irrespective of dose and duration of treatment. Among the patients who started on 400 mg twice daily, 53 percent achieved a clinically significant platelet count of³30,000/µL on day eight. Among the patients that achieved the primary endpoint, 79 percent had a platelet count³30,000/µL by day eight, and these patients had sustained responses³50,000/µL for 71 percent of the time. In addition, responders achieved platelet counts³20,000/µL above baseline 88 percent of the time. To date rilzabrutinib has been well tolerated, whether given as a monotherapy or with allowed concomitant ITP therapy (thrombopoietin receptor agonists and corticosteroids), with no reported treatment related bleeding or thrombotic events. Related treatment emergent adverse events were reported in 45% of patients and were all grade 1 or 2.
Based on this data, the Company’s goal is to initiate a pivotal Phase 3 trial, assuming no futureCOVID-19 related impact, by the end of 2020. In addition, the Company believes that a single Phase 3 trial, if successful, will be acceptable for approval in the United States, but can make no assurance thereof.
These results are preliminary in nature and may change as patients progress in the trial and as additional patients may be enrolled. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated by reference.
Pemphigus Data Release
On June 12, 2020, the Company announced the presentation as part of the virtual late-breaker session of the American Academy of Dermatology of positive data from the Phase 2 Part B open-label trial of its proprietary drug candidate, rilzabrutinib, for the treatment of pemphigus.
In the Phase 2 Part B trial of 15 patients with newly diagnosed or relapsedmild-to-severe pemphigus, rilzabrutinib demonstrated a 40% complete remission (CR) rate after 24 weeks of treatment, while the median corticosteroid (CS) dose was reduced significantly. The median CS dose was 18 mg/day (0.201 mg/kg/day) at baseline and in the 14 patients that completed 12 and 24 weeks of treatment the median CS dose decreased to 11 mg/day (0.125 mg/kg/day) at 12 weeks and decreased again to 6 mg/day (0.076 mg/kg/day) at 24 weeks. Additionally, 60 percent and 87 percent of patients achieved control of disease activity (CDA) by weeks 4 and 12, respectively. The results also demonstrated that while patients on 400 mgonce-a-day dosing were able to reach CDA, 400 mgtwice-a-day dosing is needed to achieve rapid CR rates. Related treatment emergent adverse events weremild-to-moderate and were all grade 1 or 2.
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The Company disseminates information to the public about the Company, its drug candidates and pipeline, its science and technology and other matters through various channels, including the Company’s investor relations website (https://ir.principiabio.com), SEC filings, press releases, public conference calls and webcasts, in order to achievebroad, non-exclusionary distribution of information to the public. The Company encourages investors and others to review the information it makes public through these channels, as such information could be deemed to be material information.
