Spark Therapeutics (ONCE) crashed Tuesday after its hemophilia A study results seemingly lagged those of a rival treatment from BioMarin Pharmaceutical (BMRN).
XSpark stock plunged 27.8% to 56.01 in high volume on the stock market today. Shares of BioMarin diverged, popping 7.9% higher to 105.72. Broadly, shares of biotech companies rose a fraction.
Leerink analyst Joseph Schwartz noted that BioMarin's gene therapy, valoctocogene roxaparvovec — or valrox — appears to be more effective in hemophilia A.
"Management emphasized that the hemophilia A patients treated with SPK-8011 benefited clinically with reductions in bleed rates and (factor VIII) replacement usage, but one cannot deny that the profile looks comparatively worse than BioMarin's Valrox," he said in a report to clients.
Spark's Gene Therapy
The goal of Spark's drug, SPK-8011, is to raise levels of a blood-clotting protein called factor VIII. Patients with severe hemophilia A have less than 1% of factor VIII protein in their blood. Those with moderate disease have 1%-5% factor VIII, and mild patients have 6%-49% of the protein.
Spark highlighted data from five patients who received a high dose of SPK-8011. On average, the level of factor VIII in the blood was 30% in these patients 12 weeks after receiving the drug. Responses ranged from 16%-49%, the biotech said in a news release.
But two patients had an immune response that drove factor VIII levels down to less than 5%. The two patients moved to on-demand treatment rather than continue receiving SPK-8011 as a preventive drug. One was hospitalized to receive treatment.
Spark believes that, long term, it can hit factor VIII levels of 12% at the high dose. To do this, it plans to use preventive steroids to suppress damaging immune responses. Now, Spark plans to move the high dose of SPK-8011 into Phase 3 testing.
BioMarin In Hemophilia A
Piper Jaffray analyst Christopher Raymond favors BioMarin's approach over Spark's. At week 104 after receiving valrox, higher-dose patients had factor VIII levels of 59%, on average. At the median, factor VIII levels were 46%. And there were no comparable immune responses, he said.
Raymond also wondered how likely hemophilia A patients are to enroll in Spark's late-stage study with "more consistent and robust responses" seen from valrox. Leerink's Schwartz called the decision to move SPK-8011 into Phase 3 testing "risky" based on the results so far.
"We think BioMarin will be advantaged not only with a quicker to market therapy, but a stronger data package for regulators and a better argument for adoption for payers and patients," Piper Jaffray's Raymond said in his note to clients.
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The post Why Spark Therapeutics' Crash On Hemophilia A Led This Rival To Pop appeared first on Investor's Business Daily.
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