Clinical Pipeline

Phase 1Phase 2Phase 3


Oral small molecule ribonucleotide reductase (RNR) inhibitor (Hematological Malignancies)


Ownership: Taiho

Mechanism of Action: Ribonucleotide reductase (RNR) inhibitor

Indications: Relapsed or refractory (r/r) Acute Myeloid Leukemia (AML) and other myeloid neoplasms

How this therapy can help

TAS1553, a novel small molecule ribonucleotide reductase (RNR) inhibitor, for the treatment of r/r AML and other myeloid neoplasms (high risk myeloproliferative neoplasms (MPN), including accelerated phase, and myelodysplastic syndromes (MDS)/MPNs) where approved therapies have failed or for whom known life-prolonging therapies are not available. TAS1553 is a potent inhibitor of RNR. Ribonucleotide reductase is a key enzyme that mediates the synthesis of deoxyribonucleotides (dNTPs). Ribonucleotide reductase catalyzes the reduction of ribonucleotides into dNTPs, the substrates for DNA replication. Because RNR is the gatekeeper of dNTP homeostasis, the enzyme has long been recognized as a cancer therapeutic target, due to its necessity for cell replication.

Clinical status

TAS1553 is being evaluated in a first-in-human Phase 1 clinical study in patients with r/r AML and other myeloid neoplasms.

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