2. Challenges in assessment of therapeutic efficacy
Management algorithm proposed by Jodele et al
(24) stratifies high risk TA-TMA patients
as indication for eculizumab use with therapeutic drug level monitoring.
Clinical utility of this guideline is limited in local setting as
measurement of both soluble terminal complement complex (sC5b-9) and
eculizumab drug level are not readily available in local laboratories.
Long turnaround time due to transportation to overseas accredited
laboratories limits its use in facilitating timely clinical decision
making and management. Besides, eculizumab is currently licensed only
for treating atypical hemolytic-uremic syndrome (HUS) and paroxysmal
nocturnal hemoglobinuria. Off-label use of eculizumab for TA-TMA costs
USD$6,700 per 300mg vial, which has great financial implication on
public healthcare system. Moreover, although decline in glomerular
filtration rate (GFR) and thus degree of kidney injury is better
evaluated by cystatin C (by Larsson formula) instead of serum creatinine
(by Schwartz formula) which is a late and insensitive parameter
particularly in young patients with low muscle mass and low creatinine
generation rates, cystatin C test is also not available in local
setting.