Maribavir (previously known as 1263W94) is a novel benzimidazole riboside compound. This drug was in phase III of clinical trial for the prevention of cytomegalovirus (CMV) infections in transplant patients, sponsored by ViroPharma. However, drug failed to demonstrate a higher efficacy rate than the placebo. Maribavir has activity against cytomegalovirus and Epstein-Barr virus (EBV), but not against other human herpesviruses. Maribavir’s mechanism of action is unique and is complex compared to the currently approved antivirals for CMV. Maribavir inhibits the viral UL97 kinase rather than the viral DNA polymerase. The UL97 kinase is important for viral DNA elongation, DNA packaging, and nuclear egress of encapsidated viral DNA. In addition, maribavir inhibits the EBV DNA polymerase processivity factor (BMRF1), reduces the level of certain EBV glycoproteins, and inhibits viral transcription. However, future work will be designed to address the interaction of MBV and BGLF4 and to evaluate the mechanisms through which maribavir downregulates viral transcripts. BGLF4 belongs to the family of conserved herpesvirus PKs, which includes HCMV UL97, HSV UL13, and HSV US3. Maribavir does need to be phosphorylated for its activity.

A-4250 (odevixibat) is a selective inhibitor of the ileal bile acid transporter (IBAT) that acts locally in the gut. Ileum absorbs glyco-and taurine-conjugated forms of the bile salts. IBAT is the first step in absorption at the brush-border membrane. A-4250 works by decreasing the re-absorption of bile acids from the small intestine to the liver, whichreduces the toxic levels of bile acids during the progression of the disease. It exhibits therapeutic intervention by checking the transport of bile acids. Studies show that A-4250 has the potential to decrease the damage in the liver cells and the development of fibrosis/cirrhosis of the liver known to occur in progressive familial intrahepatic cholestasis. A-4250 is a designated orphan drug in the USA for October 2012. A-4250 is a designated orphan drug in the EU for October 2016. A-4250 was awarded PRIME status for PFIC by EMA in October 2016. A-4250 is in phase II clinical trials by Albireo for the treatment of primary biliary cirrhosis (PBC) and cholestatic pruritus. In an open label Phase 2 study in children with cholestatic liver disease and pruritus, odevixibat showed reductions in serum bile acids and pruritus in most patients and exhibited a favorable overall tolerability profile.

Belzutifan (PT2977) is an orally active, small molecule inhibitor of hypoxia-inducible factor (HIF)-2alpha (HIF-2a). Upon oral administration, HIF-2alpha inhibitor PT2977 binds to and blocks the function of HIF-2alpha, thereby preventing HIF-2alpha heterodimerization and its subsequent binding to DNA. This results in decreased transcription and expression of HIF-2alpha downstream target genes, many of which regulate hypoxic signaling. This inhibits cell growth and survival of HIF-2alpha-expressing tumor cells. HIF-2alpha, the alpha subunit for the heterodimeric transcription factor HIF-2, is overexpressed in many cancers and promotes tumorigenesis.

Estetrol is the natural human fetal selective estrogen receptor modulator. It is synthesized exclusively by the human fetal liver during pregnancy. Estetrol has a moderate affinity for human estrogen A receptor (ERa) and estrogen B receptor (ERb). Estetrol may be suitable as a potential drug for human use in applications such as hormone replacement therapy (vaginal atrophy, hot flushes), contraception and osteoporosis. The most common drug-related adverse events were lower abdominal pain, nausea, headache, dysmenorrhoea, breast enlargement and acne. Estetrol had been in clinical trials for the treatment of breast and prostate cancers.

Tivozanib (formerly AV-951, KRN-951) is a potent and selective VEGFR tyrosine kinase inhibitor and inhibits angiogenesis and vascular permeability in tumor tissues. It completed phase III a trial investigation for the treatment of renal cell carcinomas, but has not been still approved. In addition, this drug is in the phase II of clinical trial for the investigation it in patients with glioblastoma and colorectal carcinoma.

Fosdenopterin (NulibryTM) is a synthetic cyclic pyranopterin monophosphate that is being developed by Origin Biosciences (a subsidiary of BridgeBio Pharma) for the treatment of molybdenum cofactor deficiency (MoCD) type A. Patients with MoCD Type A have mutations in the MOCS1 gene leading to deficient MOCS1A/B dependent synthesis of the intermediate substrate, cPMP. Substrate replacement therapy with NULIBRY provides an exogenous source of cPMP, which is converted to molybdopterin. Molybdopterin is then converted to molybdenum cofactor, which is needed for the activation of molybdenum-dependent enzymes, including sulfite oxidase (SOX), an enzyme that reduces levels of neurotoxic sulfites. Fosdenopterin was approved by the US FDA in February 2021 for use in reducing the risk of mortality in paediatric and adult patients with MoCD type A.

Sotorasib (LUMAKRAS™) is a RAS GTPase family inhibitor being developed by Amgen for the treatment of solid tumours with KRAS mutations, including non-small cell lung cancer (NSCLC) and colorectal cancer. Sotorasib is an inhibitor of KRASG12C, a tumor-restricted, mutant-oncogenic form of the RAS GTPase, KRAS. Sotorasib forms an irreversible, covalent bond with the unique cysteine of KRASG12C, locking the protein in an inactive state that prevents downstream signaling without affecting wild-type KRAS. Sotorasib blocked KRAS signaling, inhibited cell growth, and promoted apoptosis only in KRAS G12C tumor cell lines. Sotorasib inhibited KRASG12C in vitro and in vivo with minimal detectable off-target activity. In May 2021, sotorasib was granted accelerated approval by the US FDA for the treatment of adult patients with KRAS G12C-mutated locally advanced or metastatic NSCLC, as determined by an FDA-approved test, who have received at least one prior systemic therapy.

Voclosporin (Lupkynis™) is an oral calcineurin inhibitor immunosuppressant that is being developed by Aurinia Pharmaceuticals. Voclosporin is an analogue of cyclosporine with a modification at the amino acid-1 position. The drug has been designed to show improved potency against calcineurin inhibition and better metabolic stability than cyclosporine. Although the exact mechanism of voclosporin is not yet clear, it inhibits calcineurin, thereby blocking lymphocyte proliferation and T-cell mediated immune responses, as well as increasing podocyte integrity in the kidney. In January 2021, based on positive results from the pivotal phases II and III trials, oral voclosporin received its first approval in the USA for use in combination with a background immunosuppressive therapy regimen for adults with active lupus nephritis. Voclosporin is also being explored for the novel coronavirus disease 2019 (COVID-19) in kidney transplant recipients. Clinical evaluation of voclosporin for plaque psoriasis, coronary artery restenosis and rheumatoid arthritis has been discontinued and no recent development for prevention of renal transplant rejection has been identified since 2015.

Avacopan (CCX-168) an orally administered selective and potent complement 5a receptor inhibitor. Avacopan blocked the C5a binding, C5a-mediated migration, calcium mobilization, and CD11b upregulation in U937 cells as well as in freshly isolated human neutrophils. Avacopan is being developed for inflammatory and autoimmune diseases.

Difelikefalin (Korsuva™) is a synthetic peptide agonist of the kappa opioid receptor being developed by Cara Therapeutics for the treatment of pruritus. In August 2021, intravenous difelikefalin was approved in the USA for the treatment of moderate-to-severe pruritus associated with chronic kidney disease (CKD) in adults undergoing haemodialysis. Difelikefalin selectively acts on kappa opioid receptors in peripheral tissues, which contribute to pruritis and nociception. The activation of opioid receptors in peripheral neurons and keratinocytes reduces afferent (sensory) impulses towards the central nervous system, decreasing pain signals. Activating kappa opioid receptors on immune cells, including monocytes and T lymphocytes, decreases the release of pro-inflammatory chemicals such as prostaglandins.