Study: NCT04442022

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Selinexor (combination therapy)
Description: Dose: 40 mg on Days 1 and 8 of each 21-day cycle for up to 6 cycles; Route of administration: oral

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Selinexor (combination therapy)
Description: Dose: 60 mg on Days 1 and 8 of each 21-day cycle for up to 6 cycles; Route of administration: oral

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Selinexor (combination therapy)
Description: Dose: Selected dose of selinexor (from Phase 2) on Days 1 and 8 of each 21-day cycle for up to 6 cycles; Route of administration: oral

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Selinexor (combination therapy)
Description: Dose: Selected dose of selinexor (from Phase 2) on Days 1 and 8 of each 21-day cycle for up to 6 cycles; Route of administration: oral

Intervention type: DRUG
Group type: PLACEBO_COMPARATOR
Intervention: Placebo matching for Selinexor (combination therapy)
Description: Dose: Placebo matching for selected dose of selinexor (from Phase 2) on Days 1 and 8 of each 21-day cycle for up to 6 cycles; Route of administration: oral

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Rituximab (combination therapy)
Description: Dose: 375 milligram per meter square (mg/m\^2) on Day 1; Route of administration: intravenous (IV)

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Rituximab (combination therapy)
Description: Dose: 375 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Rituximab (combination therapy)
Description: Dose: 375 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: PLACEBO_COMPARATOR
Intervention: Rituximab (combination therapy)
Description: Dose: 375 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Rituximab (combination therapy)
Description: Dose: 375 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Rituximab (combination therapy)
Description: Dose: 375 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Gemcitabine (combination therapy)
Description: Dose: 1000 mg/m\^2 on Days 1 and 8; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Gemcitabine (combination therapy)
Description: Dose: 1000 mg/m\^2 on Days 1 and 8; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Gemcitabine (combination therapy)
Description: Dose: 1000 mg/m\^2 on Days 1 and 8; Route of administration: IV

Intervention type: DRUG
Group type: PLACEBO_COMPARATOR
Intervention: Gemcitabine (combination therapy)
Description: Dose: 1000 mg/m\^2 on Days 1 and 8; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Gemcitabine (combination therapy)
Description: Dose: 1000 mg/m\^2 on Days 1 and 8; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Gemcitabine (combination therapy)
Description: Dose: 1000 mg/m\^2 on Days 1 and 8; Route of administration: IV

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Dexamethasone (combination therapy)
Description: Dose: 40 mg (20 mg if patient is more than 70 years old) on Days 1, 2, 3, and 4; Route of administration: oral or IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Dexamethasone (combination therapy)
Description: Dose: 40 mg (20 mg if patient is more than 70 years old) on Days 1, 2, 3, and 4; Route of administration: oral or IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Dexamethasone (combination therapy)
Description: Dose: 40 mg (20 mg if patient is more than 70 years old) on Days 1, 2, 3, and 4; Route of administration: oral or IV

Intervention type: DRUG
Group type: PLACEBO_COMPARATOR
Intervention: Dexamethasone (combination therapy)
Description: Dose: 40 mg (20 mg if patient is more than 70 years old) on Days 1, 2, 3, and 4; Route of administration: oral or IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Dexamethasone (combination therapy)
Description: Dose: 40 mg (20 mg if patient is more than 70 years old) on Days 1, 2, 3, and 4; Route of administration: oral or IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Dexamethasone (combination therapy)
Description: Dose: 40 mg (20 mg if patient is more than 70 years old) on Days 1, 2, 3, and 4; Route of administration: oral or IV

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Cisplatin (combination therapy)
Description: Dose: 75 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Cisplatin (combination therapy)
Description: Dose: 75 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Cisplatin (combination therapy)
Description: Dose: 75 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: PLACEBO_COMPARATOR
Intervention: Cisplatin (combination therapy)
Description: Dose: 75 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Cisplatin (combination therapy)
Description: Dose: 75 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Cisplatin (combination therapy)
Description: Dose: 75 mg/m\^2 on Day 1; Route of administration: IV

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Selinexor (continuous therapy)
Description: Dose: 60 mg QW for each 28-day cycle until PD; Route of administration: oral

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Selinexor (continuous therapy)
Description: Dose: 60 mg QW for each 28-day cycle until PD; Route of administration: oral

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Selinexor (continuous therapy)
Description: Dose: 60 mg QW for each 28-day cycle until PD; Route of administration: oral

Intervention type: DRUG
Group type: PLACEBO_COMPARATOR
Intervention: Placebo matching for Selinexor (continuous therapy)
Description: Dose: Placebo matching for 60 mg selinexor QW for each 28-day cycle until PD; Route of administration: oral

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Placebo matching for Selinexor (continuous therapy)
Description: Dose: Placebo matching for 60 mg selinexor QW for each 28-day cycle until PD; Route of administration: oral