Inclusion Criteria:

          -  Multiple myeloma meeting the following criteria:

               -  Pathologically-documented diagnosis of multiple myeloma that is relapsed or is
                  refractory as defined by the following:

                    -  Relapsed after > or = 3 lines of prior therapy that must include all
                       approved and available therapies deemed eligible by the investigator,
                       inclusing at a minimum of a proteasome inhibitor (PI), an immunomodulatory
                       drug (IMiD), and, where approved and available, a CD38-directed cytolytic
                       antibody in combination in the same line or separate lines of treatment OR
                       refractory to PI, IMiD, and CD38- directed cytolytic antibody,

                    -  Subjects who could not tolerate a PI, IMiDs, or a CD38-directed cytolytic
                       antibody are eligible to enroll in the study.

               -  Measurable disease as per IMWG response criteria

          -  Eastern Cooperative Oncology Group (ECOG) Performance Status of ≤ 2

        Inclusion criteria specific to AMG 701-P±d include:

          -  Subjects must have received ≥ 2 lines of prior therapy that must include a proteasome
             inhibitor (PI), lenalidomide, and where approved and available a CD38-directed
             antibody. These therapies may be in the same line or separate lines of treatment.

          -  Subjects must have responded to at least 1 prior line with at least a PR.

          -  Subjects that have previously received pomalidomide must not have been removed from
             therapy due to toxicity attributable to pomalidomide and must be at least 6 months
             from their last dose of pomalidomide.

          -  Subjects must not have known intolerance to doses of dexamethasone up to 40 mg weekly
             (20 mg weekly if > 75 years).

        Exclusion Criteria:

          -  Known extramedullary relapse in the absence of any measurable medullary involvement

          -  Known central nervous system involvement by multiple myeloma

          -  Autologous stem cell transplantation less than 90 days prior to study day 1

          -  Recent history of primary plasma cell leukemia (within last 6 months prior to
             enrollment) or evidence of primary or secondary plasma cell leukemia at the time of
             screening

          -  Waldenstrom's macroglobulinemia

          -  Prior amyloidosis (subjects with multiple myeloma with asymptomatic deposition of
             amyloid plaques found on biopsy would be eligible if all other criteria are met)

          -  Treatment with systemic immune modulators including, but not limited to, nontopical
             systemic corticosteroids (unless the dose is ≤ 10 mg/day prednisone or equivalent),
             cyclosporine, and tacrolimus within 2 weeks before study day 1

          -  Last anticancer treatment (chemotherapy, IMiD, PI, molecular targeted therapy) < 2
             weeks prior to study day 1 or treatment with a therapeutic antibody less than 4 weeks
             prior to study day 1 as well as systemic radiation therapy within 28 days prior to
             study day 1 or focal radiotherapy within 14 days prior to study day 1.

          -  Prior treatment with any drug or construct that targets BCMA on tumor cells (eg, other
             bispecific antibody constructs, antibody drug conjugates, or CAR-T cells), other than
             Group C where prior treatment with GSK2857916 (belantamab mafodotin) is required.

        Exclusion criteria specific to AMG 701-P±d include:

          -  History of serious hypersensitivity associated with thalidomide, pomalidomide, or
             lenalidomide (> grade 3).

          -  Multiple myeloma with IgM subtype.

          -  POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and
             skin changes).

          -  Contraindication to pomalidomide or dexamethasone.

          -  Glucocorticoid therapy within 14 days prior to randomization that exceeds a cumulative
             dose of 160 mg of dexamethasone or equivalent dose of other corticosteroids.

          -  Treatment with systemic immune modulators including, but not limited to, non-topical
             systemic corticosteroids (unless the dose is ≤ 10 mg/day prednisone or equivalent),
             cyclosporine, and tacrolimus within 2 weeks before study day 1 or 4 weeks before study
             day 1 for Phase 1 dose-confirmation.

          -  Female subjects of childbearing potential with a positive pregnancy test assessed
             within 14 days prior to first dose of study drugs and/or a positive urine pregnancy
             test within 24 hours prior to first dose. In addition, females of childbearing
             potential unwilling to undergo pregnancy testing weekly during the first 4 weeks of
             pomalidomide use followed by pregnancy testing every 4 weeks in females with regular
             menses or every 2 weeks in females with irregular menstrual cycles.

          -  Male subjects with a female partner of childbearing potential and female subjects of
             childbearing potential who are unwilling to use 2 methods of contraception (1 of which
             must be highly effective during the study and for an additional 75 days (females) and
             135 days (males) after receiving the last dose of AMG 701, or 28 days after the last
             dose pomalidomide (males and females) or dexamethasone (females), whichever occurs
             later.

          -  Females who are lactating/breastfeeding or who plan to breastfeed while on study
             through 75 days after receiving the last dose of AMG 701, or 28 days after the last
             dose pomalidomide or dexamethasone, whichever occurs later.

          -  Females planning to become pregnant while on study through 75 days after receiving the
             last dose of AMG 701 or 28 days after the last dose pomalidomide or dexamethasone,
             whichever occurs later.

          -  Male subjects with a pregnant partner who are unwilling to practice abstinence or use
             a latex or synthetic condom (even if they have had a vasectomy with medical
             confirmation of surgical success) during treatment (including during dose
             interruptions) and for an additional 135 days after the last dose of AMG 701, or 28
             days after the last dose pomalidomide, whichever occurs later.

          -  Males who are unwilling to abstain from sperm donation while on study through 135 days
             after receiving the last dose of AMG 701 or 28 days after the last dose pomalidomide,
             whichever occurs later.