Besifovir (also known as LB80331), an active metabolite of LB80380 was studied for the treatment of hepatitis B.

Pyrazoloacridine is a pyrazolo[3,4,5-kl]acridine derivative patented by Warner-Lambert Co. as an anticancer agent. Pyrazoloacridine acts as topoisomerase I and II inhibitor that decrease the formation of topoisomerase-DNA adducts. In vitro experiments, Pyrazoloacridine shows efficacy against multidrug-resistant neuroblastoma doxorubicin-resistant human colon carcinoma and breast cancer cell lines. In clinical trials, Pyrazoloacridine demonstrates moderate efficacy in metastatic breast cancer and a high level of adverse events. The dose-limiting toxicity was grade 4 neutropenia. Other grade 3 and 4 toxicities include vomiting, nausea, neurotoxicity, fatigue, and anemia.

AZD1305, an antiarrhythmic agent, blocks the hERG potassium channel, the L-type calcium, and the Sodium channel protein Nav1.5. AZD1305 participated in clinical trials for the management of atrial fibrillation and Left ventricular dysfunction. The benefit-risk profile was judged as unfavorable and the AZD1305 development programme was discontinued.

Among the naturally occurring trichothecenes in food and feed, T-2 toxin is a cytotoxic fungal secondary metabolite produced by various species of Fusarium. Following ingestion, T-2 toxin causes acute and chronic toxicity and induces apoptosis in the immune system and fetal tissues. T-2 toxin is usually metabolized and eliminated after ingestion, yielding more than 20 metabolites. Consequently, there is a possibility of human consumption of animal products contaminated with T-2 toxin and its metabolites. The molecular mechanism of inhibition of protein synthesis may be the high affinity of T-2 toxin for the 60S ribosomal subunit.

PU-H71 is experimental inhibitor of Hsp90. It is being tested in clinical trials against lymphoma and solid tumors.

Annamycin is a highly lipophilic form of the anthracycline doxorubicin with the ability to bypass multidrug resistance mechanisms of cellular drug resistance. Annamycin belongs to the anthracycline class of drugs, and has a pleiotropic mechanism of action where it targets topoisomerase II, causing strand breaks in DNA. Annamycin forms complexes with DNA by intercalation between base pairs, and it inhibits topoisomerase II activity by stabilizing the DNA-topoisomerase II complex, preventing the religation portion of the ligation-religation reaction that topoisomerase II catalyzes. The agent is being evaluated in separate phase 1 and phase 2 trials in the United States and Europe. Studies in animal models showed the agent to be noncardiotoxic. Trials that included patients with leukemia showed the agent was associated with fewer dose-limiting toxicities than typically experienced with doxorubicin. The FDA granted fast track designation to Annamycin for treatment of patients with relapsed or refractory acute myeloid leukemia.

IPI-493 (17-AG, 17-Aminogeldanamycin) is the major metabolite of tanespimycin (17-AAG) and retaspimycin (17-DMAG) with potent antineoplastic activity. Hsp90 controls the proper folding, function, and stability of various "client" proteins within cells. Many of the clients of Hsp90 (such as Akt, Bcr-Abl, EGFR, Flt-3, c-Kit and PDGFR α) are oncoproteins or important cell-signaling proteins, and therefore are critical for tumor cell growth and survival. Inhibition of Hsp90 results in degradation of these proteins, which abrogates growth and survival signaling and leads to tumor cell death. IPI-493 has been used in trials studying the treatment of Advanced Malignancies.