The purpose of this study is to find out whether selinexor is an effective treatment for people who have a relapsed/refractory Wilms tumor, rhabdoid tumor, MPNST, BCOR-driven sarcoma, or another solid tumor that makes a higher than normal amount of XPO1 or has genetic changes that increase the activity of XP01.
Age ≥ 6 at the time of informed consent
Age ≥ 2 years to < 6 years at time of informed consent (Refer to Section 4.3): If PK cohort 1 is open, patients in this age range may enroll onto this cohort. If PK cohort 1 has been completed and deemed sufficient to proceed, then such patients may enroll onto the phase 2.
Consent: All patients and/or their parents or legally authorized representatives must sign a written informed consent. Assent, when appropriate, will be obtained according to institutional guidelines.
Performance: Karnofsky ≥ 60% for patients > 16 years of age and Lansky ≥ 60 for patients ≤ 16 years of age.
Prior Therapy: Has received selinexor or another XPO1 inhibitor previously.
Infection: Patients who have an uncontrolled infection are not eligible. Patients on prophylactic antibiotics or with a controlled infection within 1 week prior to C1D1 are acceptable
Transplants: Patients who have received allogeneic bone marrow transplant are potentially eligible unless they are being actively treated for GvHD. Patients who have had a prior solid organ transplantation are not eligible.
Compliance: Patients who as a result of serious medical, psychiatric, and/or social situation(s), in the opinion of the investigator, may not be able to comply with supportive care, safety monitoring, or any other key requirements of the study protocols are not eligible.