Omacetaxine mepesuccinate ( INN, trade names Synribo ), formerly named as homoharringtonine or HHT, is a pharmaceutical drug substance that is indicated for treatment of chronic myeloid leukemia (CML). HHT is a natural plant alkaloid derived from '' Cephalotaxus fortunei''. HHT and related compound esters of cephalotaxine were described first in 1970, and were the subject of intensive research efforts by Chinese investigators to clarify their role as anticancer and antileukemic agents from the 1970s until the present. It was approved by the US FDA in October 2012 for the treatment of adult patients with CML with resistance and/or intolerance to two or more

tyrosine kinase inhibitors A tyrosine kinase inhibitor (TKI) is a pharmaceutical drug that inhibits tyrosine kinases. Tyrosine kinases are enzymes responsible for the activation of many proteins by signal transduction cascades. The proteins are activated by adding a ph ...

(TKIs).

Medical uses

Omacetaxine/homoharringtonine is indicated for use as a treatment for patients with

chronic myeloid leukaemia Chronic myelogenous leukemia (CML), also known as chronic myeloid leukemia, is a cancer of the white blood cells. It is a form of leukemia characterized by the increased and unregulated growth of myeloid cells in the bone marrow and the accumulati ...

who are resistant or intolerant of

. In June 2009, results of a long-term

open label An open-label trial, or open trial, is a type of clinical trial in which information is not withheld from trial participants. In particular, both the researchers and participants know which treatment is being administered. This contrasts with a do ...

Phase II study were published, which investigated the use of omacetaxine infusions in CML patients. After twelve months of treatment, about one third of patients showed a cytogenetic response. A study in patients who had failed imatinib and who had the drug resistant T315I mutation achieved cytogenetic response in 28% of patients and hematologic response in 80% of patients, according to preliminary data. Phase I studies including a small number of patients have shown benefit in treating myelodysplastic syndrome (MDS, 25 patients) and acute myelogenous leukaemia (AML, 76 patients). Patients with solid tumors did not benefit from omacetaxine.

Adverse effects

By frequency:
Very common (>10% frequency):
* Diarrhoea * Myelosuppression^† * Injection site reactions * Nausea * Fatigue * Fever * Muscle weakness * Joint pain * Headache * Cough *

Hair loss Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scar ...

* Constipation * Nosebleeds * Upper abdominal pain * Pain in the extremities * Oedema * Vomiting * Back pain *

Hyperglycemia Hyperglycemia is a condition in which an excessive amount of glucose circulates in the blood plasma. This is generally a blood sugar level higher than 11.1 mmol/L (200 mg/dL), but symptoms may not start to become noticeable until even ...

, sometimes extreme *

Gout Gout ( ) is a form of inflammatory arthritis characterized by recurrent attacks of a red, tender, hot and swollen joint, caused by deposition of monosodium urate monohydrate crystals. Pain typically comes on rapidly, reaching maximal intens ...

* Rash * Insomnia Common (1–10% frequency): * Seizures * Haemorrhage ^† Myelosuppression, including:

thrombocytopenia Thrombocytopenia is a condition characterized by abnormally low levels of platelets, also known as thrombocytes, in the blood. It is the most common coagulation disorder among intensive care patients and is seen in a fifth of medical patients a ...

anaemia Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, th ...

neutropenia Neutropenia is an abnormally low concentration of neutrophils (a type of white blood cell) in the blood. Neutrophils make up the majority of circulating white blood cells and serve as the primary defense against infections by destroying bacteri ...

and

lymphopenia Lymphocytopenia is the condition of having an abnormally low level of lymphocytes in the blood. Lymphocytes are a white blood cell with important functions in the immune system. It is also called lymphopenia. The opposite is lymphocytosis, which ...

, in descending order of frequency. Omacetaxine mepesuccinate can cause fetal harm when administered to a pregnant woman. Women using HHT should avoid becoming pregnant and also avoid nursing while receiving HHT.

Mechanism of action

Omacetaxine is a protein

translation Translation is the communication of the meaning of a source-language text by means of an equivalent target-language text. The English language draws a terminological distinction (which does not exist in every language) between ''transla ...

inhibitor. It inhibits protein translation by preventing the initial elongation step of protein synthesis. It interacts with the ribosomal A-site and prevents the correct positioning of amino acid side chains of incoming aminoacyl-tRNAs. Omacetaxine acts only on the initial step of protein translation and does not inhibit protein synthesis from mRNAs that have already commenced translation.

References

{{Intracellular chemotherapeutic agents Orphan drugs Alkaloids Benzodioxoles Cyclopentenes Benzazepanes Methoxy compounds Heterocyclic compounds with 5 rings Esters Tertiary alcohols