FDA Approves Test for Everolimus Immunoassay

Nature Reviews Drug Discovery 8, 535-536 (July 2009)

The FDA has approved the first test to monitor blood levels of Everolimus in  kidney transplant patients.  This is a competitive inhibition assay using a Quantitative Microsphere System (QMS®).  An agglutination reaction between antibody and microsphere particle bound Everolimus is inhibited in the presence of free Everolimus in the patient sample.  From this a concentration-dependent classic aggultination inhibition curve can be acquired where a maximum rate of agglutination corresponds with the lowest Everolimus concentration.  When evalutated by Dasgupta et. al  the assay produced a direct linear correlation between 1.5 and 20ng/mL and a lower limit of 1.3ng/mL.  The researchers also noted a 46% cross-reactivity with sirolimus which is structurally similar to everolimus.  The QMS Everolimus Immunoassay from Thermofisher  provides a new immunoassay for the routine monitoring of Everolimus in whole blood.

FDA Oversight of Laboratory Developed Tests (LDTs)

The FDA has held a 2 day workshop to hear from the pubic on how best to regulate LDTs.   In the past the FDA has had the right to oversee LDT development, however not until recently decided to enforce regulation.  Multiple assays involved in transplantation (ie. HLA typing, crossmatching, C4d staining) would all fall under this new regulation.  Without federal oversight the FDA is concerned that LDTs not properly validated will put patients at risk for a missed or wrong diagnosis.  In addition, there is pressure from industry sources who want a level playing field whose tests need to be approved or cleared by the FDA.  The current lack of FDA oversight in academic labs allows for quick turn around time at a rapid bench to bedside pace. Currently, the FDA wants a risk-based application of oversight to all LDTs.  It is unclear how the FDA will enforce this regulation or how it will effect transplantation in the US.