XPOVIO® (selinexor) is indicated in combination with dexamethasone for the treatment of adult patients with relapsed or refractory multiple myeloma (RRMM) who have received at least 4 prior therapies and whose disease is refractory to at least 2 proteasome inhibitors, at least 2 immunomodulatory agents, and an anti-CD38 monoclonal antibody. This indication is approved under accelerated approval based on response rate. Continued approval for this indication may be contingent upon verification of clinical benefit in a confirmatory trial.
Thrombocytopenia: XPOVIO can cause thrombocytopenia, leading to potentially fatal hemorrhage. Thrombocytopenia was reported in 74% of patients, and was severe (Grade 3-4) in 61% of patients. Median time to onset of the first event was 22 days. Bleeding occurred in 23%, clinically significant bleeding occurred in 5%, and fatal hemorrhage occurred in <1% of patients.
Monitor platelet counts at baseline, during treatment, and as clinically indicated. Monitor more frequently during the first 2 months of treatment. Institute platelet transfusion and/or other treatments as clinically indicated. Monitor patients for signs and symptoms of bleeding and evaluate promptly. Interrupt and/or reduce dose, or permanently discontinue based on severity of adverse reaction.
Neutropenia: XPOVIO can cause neutropenia, potentially increasing the risk of infection. Neutropenia occurred in 34% of patients, and was severe (Grade 3-4) in 21% of patients. Median time to onset of the first event was 25 days. Febrile neutropenia was reported in 3% of patients.
Obtain neutrophil counts at baseline, during treatment, and as clinically indicated. Monitor more frequently during the first 2 months of treatment. Monitor patients for signs and symptoms of concomitant infection and evaluate promptly. Consider supportive measures including antimicrobials for signs of infection and use of growth factors (e.g., G-CSF). Interrupt and/or reduce dose, or permanently discontinue based on severity of adverse reaction.
Gastrointestinal Toxicity: Gastrointestinal toxicities occurred in patients receiving XPOVIO.
Nausea/Vomiting: Nausea and vomiting occurred in 72% and 41% of patients, respectively. Grade 3 nausea and vomiting occurred in 9% and 4% of patients, respectively. Median time to onset of the first nausea event and vomiting was 3 and 5 days, respectively.
Provide prophylactic 5-HT3 antagonists and/or other anti-nausea agents, prior to and during treatment with XPOVIO. Manage nausea/vomiting by dose interruption, reduction, and/or discontinuation. Administer intravenous fluids and replace electrolytes to prevent dehydration in patients at risk. Use additional anti-nausea medications as clinically indicated.
Diarrhea: Diarrhea occurred in 44% of patients, and Grade 3 diarrhea occurred in 6% of patients. Median time to onset was 15 days.
Manage diarrhea by dose modifications and/or standard anti-diarrheal agents; administer intravenous fluids to prevent dehydration in patients at risk.
Anorexia/Weight Loss: Anorexia and weight loss occurred in 53% and 47% of patients, respectively. Grade 3 anorexia and weight loss occurred in 5% and 1% of patients, respectively. Median time to anorexia and weight loss onset was 8 and 15 days, respectively.
Monitor patient weight at baseline, during treatment, and as clinically indicated. Monitor more frequently during the first 2 months of treatment. Manage anorexia and weight loss with dose modifications, appetite stimulants, and nutritional support.
Hyponatremia: XPOVIO can cause hyponatremia. Hyponatremia occurred in 39% of patients. 22% of patients experienced Grade 3 or 4 hyponatremia. Median time to onset of the first event was 8 days.
Monitor sodium level at baseline, during treatment, and as clinically indicated. Monitor more frequently during the first 2 months of treatment. Correct sodium levels for concurrent hyperglycemia (serum glucose >150 mg/dL) and high serum paraprotein levels. Treat hyponatremia per clinical guidelines (intravenous saline and/or salt tablets), including dietary review. Interrupt and/or reduce dose, or permanently discontinue based on severity of adverse reaction.
Infections: 52% of patients receiving XPOVIO experienced any grade of infection. Upper respiratory tract infection of any grade occurred in 21%, pneumonia in 13%, and sepsis in 6% of patients. Grade ≥3 infections were reported in 25% of patients, and deaths resulting from an infection occurred in 4% of patients. The most commonly reported Grade ≥3 infections were pneumonia (9%) and sepsis (6%). The median time to onset was 54 days for pneumonia and 42 days for sepsis. Most infections were not associated with neutropenia and were caused by non-opportunistic organisms.
Neurological Toxicity: Neurological toxicities occurred in patients receiving XPOVIO. Neurological adverse reactions including dizziness, syncope, depressed level of consciousness, and mental status changes (including delirium and confusional state) occurred in 30% of patients, and severe events (Grade 3-4) occurred in 9% of patients. Median time to the first event was 15 days.
Optimize hydration status, hemoglobin level, and concomitant medications to avoid exacerbating dizziness or mental status changes.
Embryo-Fetal Toxicity: XPOVIO can cause fetal harm when administered to a pregnant woman.
Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential and males with a female partner of reproductive potential to use effective contraception during treatment with XPOVIO and for 1 week after the last dose.
The most common adverse reactions (ARs) (incidence ≥20%) were thrombocytopenia, fatigue, nausea, anemia, decreased appetite, decreased weight, diarrhea, vomiting, hyponatremia, neutropenia, leukopenia, constipation, dyspnea, and upper respiratory tract infection.
The treatment discontinuation rate due to ARs was 27%. Reduction or interruption of XPOVIO dose occurred in 53% and 65.3% of patients, respectively. The most frequent ARs requiring permanent discontinuation in ≥4% of patients included fatigue, nausea, and thrombocytopenia. The rate of fatal ARs was 8.9%.
Of the 202 patients with RRMM who received XPOVIO, 49% were ≥65 years old, while 11% were ≥75 years old. No overall difference in effectiveness of XPOVIO was observed in the two age groups. Patients ≥75 years old had a higher incidence of discontinuation due to an AR than younger patients (44% vs 27%), higher incidence of serious ARs (70% vs 58%), and higher incidence of fatal ARs (17% vs 9%).
The effect of end-stage renal impairment (CLCR <15 mL/min) or hemodialysis on XPOVIO pharmacokinetics is unknown. The effect of moderate and severe hepatic impairment on XPOVIO pharmacokinetics is unknown.
No dedicated drug interaction studies have been performed with XPOVIO.
Please see full Prescribing Information.
Reference: 1. XPOVIO (selinexor) [package insert]. Newton, MA: Karyopharm Therapeutics, Inc.; July 2019.