Quizartinib (AC220) is an orally bioavailable, small molecule receptor tyrosine kinase inhibitor that is being developed by Daiichi Sankyo Company (previously Ambit Biosciences) and Astellas Pharma as a treatment for acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL) and advanced solid tumours. The highest affinity target identified for Quizartinib was FLT3. The only other kinases with binding constants within 10-fold that for FLT3 were the closely related receptor tyrosine kinases KIT, PDGFRA, PDGFRB, RET, and CSF1R. Kinase inhibition of (mutant) KIT, PDGFR and FLT3 isoforms by quizartinib leads to potent inhibition of cellular proliferation and induction of apoptosis in in vitro leukemia models as well as in native leukemia blasts treated ex vivo.

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.

Upadacitinib (ABT-494) is a Janus kinase 1 (JAK1) inhibitor currently being developed by AbbVie for the treatment of rheumatoid arthritis (RA), Crohn’s disease, ulcerative colitis, atopic dermatitis, and psoriatic arthritis. It is also being investigated as a potential treatment for people with active ankylosing spondylitis (AS). Currently, upadacitinib is being evaluatedin six global phase III studies in RA and twophase III studies in psoriatic arthritis (PsA), inaddition to phase II studies in Crohn’s disease and atopicdermatitis and a combined phase II/III study inulcerative colitis. Upadacitinib is a potent and selective Janus kinase (JAK) 1 inhibitor with an IC50 of 43 nM.

Gilteritinib, also known as ASP2215, is a potent FLT3/AXL inhibitor, which showed potent antileukemic activity against AML with either or both FLT3-ITD and FLT3-D835 mutations. In in vitro, among the 78 tyrosine kinases tested, Gilteritinib inhibited FLT3, LTK, ALK, and AXL kinases by over 50% at 1 nM with an IC50 value of 0.29 nM for FLT3, approximately 800-fold more potent than for c-KIT, the inhibition of which is linked to a potential risk of myelosuppression. Gilteritinib inhibited the growth of MV4-11 cells, which harbor FLT3-ITD, with an IC50 value of 0.92 nM, accompanied with inhibition of pFLT3, pAKT, pSTAT5, pERK, and pS6. Gilteritinib decreased tumor burden in bone marrow and prolonged the survival of mice intravenously transplanted with MV4-11 cells. In previous preclinical studies, gilteritinib has demonstrated superior antitumor effects when given in combination with AraC and either DNR or IDR compared with combination chemotherapy. In November 2018, the FDA approved gilteritinib for treatment of adult patients with relapsed or refractory acute myeloid leukemia (AML) with a FLT3 mutation as detected by an FDA-approved test.

Fostamatinib is a pro-drug of a Syk inhibitor R406 initially developed by Rigel Pharmaceuticals, but then in-licensed by AstraZeneca. It reached phase III of clinical trials for such diseases as Rheumatoid Arthritis and Immune Thrombocytopenic Purpura, however, AstraZeneca decided not to proceed with regulatory filings and return the rights to the compound to Rigel Pharmaceuticals. In 2018 the drug was approved by the FDA for treatment of chronic immune thrombocytopenia. Fostamatinib is being developed for Autoimmune Hemolytic Anemia (phase II), graft versus host disease (phase I) and ovarian cancer (phase I).

Fostamatinib is a pro-drug of a Syk inhibitor R406 initially developed by Rigel Pharmaceuticals, but then in-licensed by AstraZeneca. It reached phase III of clinical trials for such diseases as Rheumatoid Arthritis and Immune Thrombocytopenic Purpura, however, AstraZeneca decided not to proceed with regulatory filings and return the rights to the compound to Rigel Pharmaceuticals. In 2018 the drug was approved by the FDA for treatment of chronic immune thrombocytopenia. Fostamatinib is being developed for Autoimmune Hemolytic Anemia (phase II), graft versus host disease (phase I) and ovarian cancer (phase I).

Dacomitinib is an oral, once-daily, pan-HER inhibitor. It is an irreversible inhibitor of HER-1 (EGFR), HER-2 and HER-4 tyrosine kinases. Dacomtinib is being evaluated in phase 3 clinical trials against nonsmall-cell lung cancer. Direct comparison with erlotinib did not show superiority of dacomtinib, but subgroup analysis have demonstrated that subgroup with exon 19 deletion had favorable outcomes with dacomitinib. In addition to nonsmall-cell lung cancer dacomtinib is being evaluated against esophagus, head and neck and other neoplasms. Due to its ability to pass through blood-brain barrier, dacomitinib can be used to treat brain tumors.

Neratinib (HKI-272) is a pan-HER inhibitor, this irreversible tyrosine kinase inhibitor binds and inhibits the tyrosine kinase activity of epidermal growth factor receptors, EGFR (or HER1), HER2 and HER4, which leads to reduced phosphorylation and activation of downstream signaling pathways. Neratinib is a modified form of the discontinued compound pelitinib, and was originally being develoAdditionally, phase II development of oral neratinib as a neoadjuvant therapy for breast cancer, as a second-line therapy for non-small cell lung cancer, and for other solid tumours is also in progress in numerous countries worldwide. ped by Wyeth (later Pfizer). Oral neratinib is awaiting approval as an extended adjuvant therapy for breast cancer in the EU and in the US. Blocking HER2 function by a small molecule kinase inhibitor, such as neratinib, represents an attractive alternate strategy for the growth inhibition of HER2-positive tumours.