Di-22:6-bis(monoacylglycerol)phosphate: A clinical biomarker of drug-induced phospholipidosis for drug development and safety assessment.

The inability to routinely monitor drug-induced phospholipidosis (DIPL) presents a challenge in pharmaceutical drug development and in the clinic. Several nonclinical studies have shown di-docosahexaenoyl (22:6) bis(monoacylglycerol) phosphate (di-22:6-BMP) to be a reliable biomarker of tissue DIPL that can be monitored in the plasma/serum and urine. The aim of this study was to show the relevance of di-22:6-BMP as a DIPL biomarker for drug development and safety assessment in humans. DIPL shares many similarities with the inherited lysosomal storage disorder Niemann-Pick type C (NPC) disease. DIPL and NPC result in similar changes in lysosomal function and cholesterol status that lead to the accumulation of multi-lamellar bodies (myeloid bodies) in cells and tissues. To validate di-22:6-BMP as a biomarker of DIPL for clinical studies, NPC patients and healthy donors were classified by receiver operator curve analysis based on urinary di-22:6-BMP concentrations. By showing 96.7-specificity and 100-sensitivity to identify NPC disease, di-22:6-BMP can be used to assess DIPL in human studies. The mean concentration of di-22:6-BMP in the urine of NPC patients was 51.4-fold (p ≤ 0.05) above the healthy baseline range. Additionally, baseline levels of di-22:6-BMP were assessed in healthy non-medicated laboratory animals (rats, mice, dogs, and monkeys) and human subjects to define normal reference ranges for nonclinical/clinical studies. The baseline ranges of di-22:6-BMP in the plasma, serum, and urine of humans and laboratory animals were species dependent. The results of this study support the role of di-22:6-BMP as a biomarker of DIPL for pharmaceutical drug development and health care settings.

Bis(monoacylglycerol)phosphate as a non-invasive biomarker to monitor the onset and time-course of phospholipidosis with drug-induced toxicities.

IMPORTANCE TO THE FIELD: Drug-induced phospholipidosis (PL) is a phospholipid storage disorder characterized by the accumulation of multi-lamellar bodies (myeloid bodies) in tissues. A major unanswered question is whether PL represents a benign adaptive response, symptom or early event in drug toxicity. The absence of a non-invasive biomarker to monitor tissue PL has made it difficult to determine the prevalence and implications of PL in the clinic. As a result, the interpretation of PL in risk assessment remains uncertain in preclinical and clinical drug development. AREAS COVERED IN THIS REVIEW: This review describes the rationale for bis(monoacylglycerol)phosphate (BMP) as a biomarker of PL and explores the potential links between PL and the toxicities of drugs. WHAT THE READER WILL GAIN: The similarities between the hypothesized roles of BMP in PL and Niemann-Pick type C disease are discussed. The potential implications of PL for cellular function are described in the context of drug-induced QT prolongation, myopathy and renal toxicity. TAKE HOME MESSAGE: A specific species of BMP, di-docosahexaenoyl-BMP, should be investigated further as a non-invasive biomarker to monitor the onset and time course of PL and to better understand the functional consequences which could contribute to the toxicities of drugs.