Bob,
Thrombocytopenia has also been a problem with bexxar. For this the bexxar abstract said <10K in 4%, but 10K is too low a threshold to compare. (The Zev abstract used Grade 4, which is platelets <25K.)
FYI, FWIW, etc. - a few years ago, the NCI definition of grade 4 thrombocytopenia was changed from the <25K platelets that you mention to a new standard of <10K (as reported by the Bex investigators). So I think we may have apples/apples comparisons here we can do on hematological AE's between Bex and Zev, at least in terms of criteria reported (that is, assuming that the Zev "Grade 4" is indeed based on the new <10K standard, not certain of that because they don't say in the abstract). We can do some level of apples/apples on neutropenia as well because Bex investigators report based on ANC < 500, which is NCI grade 4.
BTW, link junkies may want to check out the following - NCI has a great site for their CTEP (Cancer Therapy Evaluation Program) - ctep.info.nih.gov
One of the things you can find here is the NCI "CTC" (Common Toxicity Criteria), the NCI standards for grading treatment toxicity (it's here that I saw that the grade 4 platelets standard had been lowered from <25K to <10K). Here's a direct link to the CTC:
ctep.info.nih.gov
Click on "Common Toxicity Criteria Document" to download all the criteria. Click on "Common Toxicity Criteria Manual" to download some good info on how to interpret the criteria.
Anyway, back to Bex vs. Zev hematological adverse events... I think the results point toward a superior profile for Bexxar, although perhaps not as superior as I had expected, and there are some differences in the patient populations involved in the samples we have to look at from ASH so we don't truly have apples/apples (this is based on assumption that Zev results were reported based on current NCI CTC of gr4 platelets defined as <10K):
Zev ("Rituxan refractory" study) vs. Bex ("overall" report)
gr4 platelets <10K: Zev 8% vs. Bex 3%
gr4 ANC <500: Zev 23% vs. Bex 17%
More I look at this, more I wish there were better publicly available data (like this) reported from earlier Bex and Zev results, but it seems hard to come by. Would make possible some more refined comparisons, closer to apples/apples...
Cheers,
Gordon |
