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FDA Approves Xpovio for Relapsed/Refactory Multiple Myeloma

The U.S. Food and Drug Administration (FDA) has granted accelerated approval to Xpovio (selinexor, Karyopharm Therapeutics) a combination treatment for adults with relapsed/refractory multiple myeloma (RRMM) who have received at least 4 prior therapies, and whose disease has shown to be resistant to other forms of treatments that include two proteasome inhibitors (protein complexes which degrade unneeded or damaged proteins), two immunomodulatory agents, and an anti-CD-38 monoclonal antibody.1,2

Refractory conditions generally are those that have not responded to previous treatment. For the treatment of multiple myeloma, selinexor tablets are administered in combination with dexamethasone, a corticosteroid.

Approval based on clinical trial data

FDA approval was based on the phase IIb STORM clinical trial of a subset of 83 adults with RRMM. Trial participants were given selinexor and dexamethasone. The trial measured the overall response rate, which was 25.3%. The median time to first response was four weeks, with a range from one to ten weeks. The median duration of response was 3.8 months.1,2 Continued approval is contingent upon the results of an ongoing confirmatory trial, which is known as the phase III BOSTON study.2 Significant safety concerns were raised in an original STORM study.2

How selexinor works

A first-in-class SINE (Selective Inhibitor of Nuclear Export) compound, selinexor binds to and inhibits the nuclear export protein exportin-1 (XPO1). It traps tumor suppressor proteins within the cancer cells and blocks the export process preventing abnormal cell proliferation.2

The FDA approval process used Fast Track designation to expedite the evaluation because, if approved, it could provide clinically meaningful treatment for cases of RRMM that have no other available therapy. Selinexor was also granted status as an Orphan Drug, one that treats rare diseases.1,2

Multiple myeloma is a cancer that starts in plasma cells, the white blood cells that produce antibodies. It currently has no known cause or cure. Sometimes referred to as plasma cell myeloma, it is characterized by a buildup of abnormal plasma cells in the bone marrow that form tumors in the bones. As antibody production increases, it can cause a thickening of blood which can prevent the bone marrow from producing a sufficient amount of healthy blood cells. Multiple myeloma is more common in older people and in the African American population.1

Possible side effects of selinexor

According to the FDA, the most common side effects of selinexor are:

  • Leukopenia- low white blood cell count
  • Neutropenia- low neutrophil count
  • Thrombocytopenia- low platelet count
  • Anemia-low red blood cell count
  • Hyponatremia- low blood sodium levels
  • Vomiting, nausea, and diarrhea or constipation
  • Decrease in appetite and loss of weight
  • Upper respiratory infections1

This is not a complete list of all possible side effects of selinexor. As when starting any new drug, first discuss with your doctor all medications, supplements and vitamins you take.

Important things to know about selinexor

Selinexor is expected to be commercially available mid-July 2019 for patients in the U.S. It is also being considered for a Marketing Authorization Application by the European Medicines Agency (EMA) for the same indication. The proposed starting dosage of selinexor is 80 mg orally on days 1 and 3, weekly until disease progression, unacceptable toxicity, or death. Dexamethasone dosage is at 20 mg orally weekly, also on days 1 and 3.2

People taking selinexor should be monitored by their physicians for changes in blood counts. Selinexor should not be taken with other medications that can cause dizziness or confusion, and patients should avoid activities where dizziness could be a problem. Effective contraception should be used by women of reproductive age and men with a female partner while being treated with selinexor. Women who are pregnant or breastfeeding should not take selinexor because it may cause harm to a developing fetus or newborn.1

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The Blood-Cancer.com team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

Comments

  • Ann Harper moderator
    3 months ago

    It’s such a shame that these drugs cause so many side effects. I wish so much for a medicine that can increase the quantity as well as the quality of our lives. More than that, I wish for a cure.

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