Pladienolide B is a potent spliceosome inhibitor, a macrolide isolated from Streptomyces obtusususus Mer-12, which targets the SF3B1 subunit of the spliceosome.Pladienolide B exerts its antitumor effects by inhibiting pre-mRNA splicing and inducing necrosis.Pladienolide B possesses antitumor activity and can be used to study leukemia and lymphoid tumors. Pladienolide B has antitumor activity and can be used to study leukemia and lymphoid tumors.