A proprietary antisense oligonucleotide targeting a novel non-coding mitochondrial RNA (ncmtRNA), with potential antineoplastic activity. Upon administration, mulnitorsen binds to ncmtRNA, which is overexpressed in rapidly proliferating cells, such as cancer cells, and not expressed in resting cells. This may decrease the expression of the ncmtRNA, which may inhibit cell proliferation and eventually induce apoptosis in susceptible cancer cells. The proprietary mitochondrial RNA (mtRNA) belongs to the family of non-coding RNAs (ncRNA); it contains an inverted repeat (IR) of 815 nucleotides (nt), which can form a covalent link to the 5' end of the mitochondrial 16S ribosomal RNA (16S mtrRNA).