Phosphopantothenic acid is an amidoalkyl phosphate that is the 4-phosphate derivative of (R)-pantothenic acid. Phosphopantothenic acid is not permeable to cell membranes due to its anionic character, consistent with the observation that systemic administration of Phosphopantothenic acid does not restore CoA levels in cellular and mouse models

XK-469 (2-[4-(7-chloro-2-quinoxalinyloxy)phenoxy]-propionic acid) is a novel synthetic quinoxaline phenoxypropionic acid derivative. The R-isomer of XK-469 was approximately twice as effective as the S-isomer of XK-469R. R( )-isomers induce reversible protein DNA crosslinks in mammalian cells. It acts as a selective topoisomerase IIβ inhibitor. A phase I study was performed to determine the safety and pharmacokinetics of XK-469, (R)- in patients with various neoplasms.

Motesanib (AMG 706), a novel nicotinamide, was identified as a potent, orally bioavailable inhibitor of the VEGFR1/Flt1, VEGFR2/kinase domain receptor/Flk-1, VEGFR3/Flt4 and Kit receptors. Motesanib was expected to reduce vascular permeability and blood flow in human tumours. A phase III trial of motesanib in combination with paclitaxel and carboplatin in non-squamous NSCLC has been terminated by Takeda and subsequently the development was discontinued. Motesanib has also been investigated up to phase II in breast, thyroid, colorectal and gastrointestinal stromal tumours. However, development has been discontinued in these indications.