RARA and acute promyelocytic leukemia: Furthermore, in APL patients treated with ATRA-based targeted therapy, PB lnc-LOC was positively correlated with PML-RARα transcripts or MRD values in BM samples, indicating that PB lnc-LOC could reflect the MRD status of APL patients and may be used as a noninvasive treatment surveillance marker for APL.