The purpose of this study is to find out if continued monitoring of side effects from Selinexor and prescribed medication to prevent side effects helps improve symptoms, quality of life, and ability to continue the treatment longer.

The primary objective of this study is to evaluate control of treatment-related and cancer-associated symptoms over the first three months of therapy with selinexor in Veterans who participate in a telehealth symptom management intervention.

The secondary objectives are:

• To describe characteristics of patients treated with selinexor.
• To describe adherence with the telehealth intervention.
• To define the type and frequency of adverse events that patients experience while taking selinexor.
• To describe the duration of selinexor therapy and evaluate adherence and dose intensity of selinexor in VA cancer patients receiving a telehealth symptom management intervention.
• To describe concomitant medication usage in patients treated with selinexor.
• To assess quality of life in patients treated with selinexor in the VA.
• To estimate progression-free survival in VA cancer patients treated with selinexor.

Inclusion Criteria:

• Diagnosis of B-cell malignancy: either relapsed or refractory multiple myeloma or diffuse large B-cell lymphoma, meeting the FDA-approved indication for Selinexor treatment.
• Requiring therapy as assessed by the treating oncology provider.
• Prior authorization drug request for selinexor approved by VA oncology pharmacist.
• Subject age 18 years or older.
• Subject willing and able to perform video or telephone research visits.
• Subjects must be able to read and comprehend English.
• Subject must be a Veteran receiving cancer care from a VA facility affiliated with the National Teleoncology Program.
• Patients must be enrolled prior to starting Selinexor.

Exclusion Criteria:

• Any prior or current therapy with selinexor.
• Any medical, psychiatric, or cognitive issue that the principal investigator or the subject's oncologists believes would prevent participation or completion of the study.
• Individuals who are vulnerable to coercion or undue influence.
• Any individuals or populations that may temporarily or permanently require additional considerations include such as those susceptible to coercion or undue influence (e.g., patients with limited or no treatment options, socially and economically disadvantaged persons).
• Current selinexor therapy that is part of an investigational clinical trial.

Enrolled subjects will be Veterans with either relapsed/refractory multiple myeloma or diffuse large B-cell lymphoma who will be initiating Selinexor or Selinexor-based therapy, as recommended by treating oncologist.