Selinexor is a synthetic small-molecule anticancer active pharmaceutical ingredient belonging to the class of selective inhibitors of nuclear export (SINE). It is an orally active inhibitor of exportin 1 (XPO1/CRM1), a major nuclear transport protein responsible for exporting numerous regulatory proteins and tumor-suppressor proteins from the cell nucleus. Selinexor is marketed in the United States as XPOVIO and in the European Union as Nexpovio. Its development code is KPT-330.
Selinexor API is a chemically synthesized small-molecule drug substance with the molecular formula C₁₇H₁₁F₆N₇O and molecular weight 443.3 g/mol. Its primary CAS number is 1393477-72-9, and FDA GSRS assigns the substance UNII 31TZ62FO8F. PubChem identifies selinexor as a triazole-containing compound incorporating pyrazine, hydrazide and bis(trifluoromethyl)phenyl structural features.
The substance is also known as KPT-330 and is chemically identified as (Z)-3-[3-[3,5-bis(trifluoromethyl)phenyl]-1,2,4-triazol-1-yl]-N′-pyrazin-2-ylprop-2-enehydrazide. The defined Z configuration is an important structural characteristic of the active pharmaceutical ingredient.
Selinexor is an oncology API used in pharmaceutical products for the treatment of multiple myeloma. According to the current U.S. prescribing information updated in 2026, XPOVIO is indicated in combination with bortezomib and dexamethasone for adult patients with multiple myeloma who have received at least one prior therapy. It is also indicated in combination with dexamethasone for adults with relapsed or refractory multiple myeloma who have received at least four prior therapies and whose disease is refractory to at least two proteasome inhibitors, at least two immunomodulatory agents and an anti-CD38 monoclonal antibody.
An important current regulatory update is that the U.S. accelerated approval for the diffuse large B-cell lymphoma (DLBCL) indication was removed in April 2026. Therefore, older product pages should not continue to describe DLBCL as a current U.S. labeled indication without qualification.
Selinexor selectively inhibits XPO1/CRM1, the principal nuclear export protein for a broad range of cargo proteins. XPO1 inhibition causes accumulation of tumor-suppressor proteins and other regulatory proteins within the nucleus. This alters cellular signaling and can promote cell-cycle arrest and apoptosis in malignant cells. Selinexor is therefore classified as a nuclear export inhibitor rather than a conventional cytotoxic chemotherapy agent.
Selinexor is a non-ionized synthetic organic molecule containing fluorinated aromatic, triazole, pyrazine and hydrazide functionalities. PubChem reports a molecular formula of C₁₇H₁₁F₆N₇O, molecular weight of 443.3 g/mol, CAS 1393477-72-9, and InChIKey DEVSOMFAQLZNKR-RJRFIUFISA-N.
Available analytical reference data report selinexor as a solid substance. Research-grade reference materials have reported high chromatographic purity, but such values should not be confused with an official commercial API release specification.
Selinexor API requires appropriate controls for identity, assay, related substances, stereochemical integrity, residual solvents, elemental impurities and other applicable pharmaceutical quality attributes. USP notes that drug-substance monographs and impurity controls are important components of pharmaceutical quality systems; however, a universally accessible current USP numerical release specification for Selinexor was not verified during this research.
For an API manufacturing specification, validated chromatographic methods such as HPLC are appropriate for assay and related-substance determination. Spectroscopic techniques such as IR and NMR can support structural identification. Residual solvent and elemental impurity controls should follow the applicable ICH and regulatory requirements.
Selinexor is a chemically synthesized small-molecule API. Pharmaceutical manufacturing requires controlled raw materials, reaction conditions, purification, drying and packaging, together with validated analytical procedures for identity, purity and assay.
Particular attention should be given to control of process-related impurities and the defined Z-isomer, because stereochemical or geometric integrity is an important aspect of the chemical identity of selinexor.
Selinexor has a molecular weight of 443.3 g/mol. Research analytical sources report that the compound is insoluble in water and soluble in organic solvents such as DMSO and ethanol under specified laboratory conditions. These research solubility values should not be presented as pharmaceutical API release specifications.
Selinexor API should be packaged in suitable pharmaceutical-grade, well-closed containers that protect the material from contamination, moisture and environmental exposure. Storage conditions should be established from validated stability studies and the applicable API specification.
Research-grade selinexor is commonly stored under refrigerated or frozen laboratory conditions, but these research conditions should not automatically be transferred to a commercial pharmaceutical API specification.
Typical documentation for Selinexor API may include:
A qualified Selinexor API manufacturer should maintain controlled chemical manufacturing processes, validated analytical methods and comprehensive pharmaceutical quality systems. Consistent control of assay, related substances, identity, stereochemical integrity and process-related impurities is essential for producing reliable Selinexor API for oncology pharmaceutical development and manufacturing.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |