As I was reading some information about Xolair, I ran across a statement by Novartis reporting a dose-related thrombocytopenia at serum concentrations in excess of maximum human exposure in primates. Do you recommend routinely checking a cbc prior to starting Xolair and periodically during treatment? If yes, how often should we be checking it during treatment? Thank you.


Thank you for your inquiry.

No, we do not recommend checking a complete blood count prior to starting Xolair, nor checking periodically during treatment for thrombocytopenia. The reasons for this are summarized in the abstract from a review article copied for you below. If you wish further, more detailed discussion of the reasons behind this conclusion, I have copied below for you two links to websites speaking to this issue. One is a statement from the FDA.

Thank you again for your inquiry and we hope this response is helpful to you.

Briefing Document on Safety
BLA STN 103976/0
Genentech, Inc.
Omalizumab (Xolair) (recombinant humanized monoclonal antibody to IgE) for treatment of allergic asthma

Omalizumab Does Not Cause Thrombocytopenia

Safety and tolerability of omalizumab
Clinical & Experimental Allergy
Volume 39, Issue 6, pages 788–797, June 2009
Background: Omalizumab (Xolair®) is a recombinant humanized monoclonal anti-IgE antibody with proven efficacy in patients with moderate-to-severe and severe persistent allergic (IgE-mediated) asthma.
Objective: To review clinical study data to assess the safety profile of omalizumab.
Methods: We analysed the safety of omalizumab using data from completed clinical studies (up to 1 year) involving more than 7500 patients with asthma, rhinitis or related conditions and up to 4 years in one study of patients with severe allergic asthma, as well as post-marketing safety data. Analysis focuses on the risk of immune-system effects, hypersensitivity reactions, malignant neoplasia, parasitic infections and thrombocytopenia.
Results: Omalizumab exhibited a good safety and tolerability profile that was maintained up to 4 years in one study. The incidence of anaphylaxis was 0.14% in omalizumab-treated patients and 0.07% in control patients. No omalizumab-treated patient developed measurable anti-omalizumab antibodies. Post-marketing, based on estimated exposure of 57 300 patients (June 2003–December 2006), the frequency of anaphylaxis attributed to omalizumab use was estimated to be at least 0.2% of patients. Current clinical trial data do not support an increased risk of malignant neoplasia or thrombocytopenia with omalizumab.
Conclusion: Data indicate that the proven efficacy of add-on omalizumab in patients with moderate-to-severe or severe allergic asthma is accompanied by a favourable safety and tolerability profile.

Phil Lieberman, M.D.

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