NEW TEST ANNOUNCEMENT

CD-33-SNP (CPT code 81479)

With the renewed interest in AML treatment using Gemtuzumab Ozogamicin (GO; Mylotarg), HematoLogics has developed a new test that identifies a biomarker for patients that will respond to the drug. A single allele change that causes loss of the CD33 IgV domain binding site can make binding of GO impossible.

By sequencing, looking at this single SNP and determining the amino acids at this site, we help guide which patient may respond to GO and which will not. If the site is C>C binding can occur while if it is C>T or T>T OG can’t bind to the site and the patient will not respond to the treatment.

Sample Case

Assay: CD33 Single Nucleotide Polymorphism Analysis
Results/Conclusions: POSITIVE- C>T p.A14V (rs12459419)

The specimen tested heterozygous positive for the presence of a C>T, p.A14V single nucleotide polymorphism (rs12459419) in CD33 (genotype CT)

Presence of the T-alleles has recently been correlated to resistance to treatment with gemtuzumab ozogamicin (GO; Mylotarg®)1. Presence of a homozygous rs12459419 C>T (p.A14V) (TT genotype) polymorphism in Exon 2 of CD33 may be associated with favorable prognosis and decreased CD33 expression levels.2

The myeloid antigen CD33 is expressed on leukemic blasts in the majority of AML and elevated expression levels are associated with inferior outcome in pediatric AML.3   Recently, CD33 nonsynonymous coding single nucleotide polymorphisms  ( rs12459419 and rs35112940) and the  3’ UTR SNP rs1803254 have been identified and their presence may negatively impact clinical response to gemtuzumab ozogamicin (GO; Mylotarg),a CD33 targeting  toxin- conjugated CD33 antibody with efficacy in a subset of patients with AML.4  In addition, presence of  rs35112940 AA and AG genotypes may be negatively correlated with clinical outcome.2

References:

  1. Lamba, JK.et al. Leukemia 2009. 23:402-404
  2. Mortland L et al. Clincial Cancer Res 2013 19:1620-1627
  3. Pollard JA et al Blood 2012 119:3705-3711
  4. Burnett AK et al J Clin Oncol. 2011;29:369-377

Sample Requirements for CD33:
Minimum 5mL of peripheral blood or 3 mL of Bone Marrow submitted in EDTA (Purple Top) tube and shipped within 24 hours.

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