Alternate Doses and Dosing Schedules of Belantamab Mafodotin for Treatment of Triple-Class Refractory Multiple Myeloma

Inclusion Criteria: * Age \>= 18 years * Eastern Cooperative Oncology Group (ECOG) performance status 0, 1, 2 * Histologically or cytologically confirmed diagnosis of multiple myeloma (MM), as defined in International Myeloma Working Group (IMWG) criteria, and: * If patients have undergone stem cell transplantation (SCT), day 0 of SCT must be \> 100 days prior to registration to be eligible for the study * Has had disease progression after \>= 3 prior lines of anti-myeloma treatments including one proteasome inhibitor (eg. bortezomib, carfilzomib or ixazomib), one immunomodulatory agent (eg.thalidomide, lenalidomide or pomalidomide) and one anti-CD38 monoclonal antibody (eg.daratumumab or isatuximab) * Prior non-belantamab mafodotin anti-BCMA agent exposure is allowed; patients with prior treatment with an anti-BCMA chimeric antigen receptor (CAR)-T or bispecific antibody will be allowed to participate in the study * Has measurable disease with at least one of the following: * Serum M-protein \>= 0.5 g/dL (\>= 5 g/L) * Urine M-protein \>= 200 mg/24 h * Serum free light chain (FLC) assay: Involved FLC level \>= 10 mg/dL (\>= 100 mg/L) and an abnormal serum free light chain ratio (\< 0.26 or \> 1.65) * Note: Patients with non-secretory disease will be allowed to participate * Absolute neutrophil count \>= 0.75 x 10\^9/L (=\< 28 days prior to registration) * Without growth factor support, blood transfusion, or platelet stimulating agents for the past 14 days, excluding erythropoietin * Hemoglobin \>= 7.0 g/dL (=\< 28 days prior to registration) * Without growth factor support, blood transfusion, or platelet stimulating agents for the past 14 days, excluding erythropoietin * Platelets \>= 50 x 10\^9/L (=\< 28 days prior to registration) * Without growth factor support, blood transfusion, or platelet stimulating agents for the past 14 days, excluding erythropoietin * Total bilirubin =\< 2.0 x upper limit of normal (ULN) (=\< 28 days prior to registration); (total bilirubin \>= 2.0 x ULN is acceptable if bilirubin is fractionated and direct bilirubin is \< 35%) * Alanine aminotransferase =\< 2.5 x ULN (=\< 28 days prior to registration) * Aspartate transaminase =\< 2.5 x ULN (=\< 28 days prior to registration) * Estimated glomerular filtration rate (eGFR) \>= 30 mL/min/1.73 m\^2 (=\< 28 days prior to registration) * As calculated by Modification of Diet in Renal Disease (MDRD) formula * Spot urine \[albumin/creatinine ratios (spot urine)\] =\< 500 mg/g (56 mg/mmol) OR urine dipstick negative/trace \[if \>1+ only eligible if confirmed =\< 500 mg/g (56 mg/mmol) by albumin/creatinine ratio (spot urine from first void)\] (=\< 28 days prior to registration) * Negative pregnancy test done =\< 7 days prior to registration, for persons of childbearing potential only. Both females and males must agree to follow the instructions * NOTE: If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required * Provide written informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in the study protocol * Willingness to provide mandatory blood specimens for correlative research * Willing to return to enrolling institution for follow-up (during the Active Monitoring Phase of the study) Exclusion Criteria: * Active plasma cell leukemia at the time of screening. Symptomatic amyloidosis, active POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal plasmaproliferative disorder, myeloma protein, and skin changes), Waldenstrom Macroglobulinemia * Prior belantamab mafodotin therapy. However, patients with prior exposure to another non-belantamab mafodotin anti-BCMA agent such as an anti-BCMA CAR-T or anti-BCMA bispecific antibody will be allowed to participate in the study * Systemic active infection requiring treatment * Any unresolved toxicity \>= grade 2 from previous treatment except for alopecia, or peripheral neuropathy up to grade 2 * Any major surgery =\< 4 weeks prior to registration * Any serious and/or unstable pre-existing medical, psychiatric disorder or other conditions (including lab abnormalities except renal impairment) that could interfere with participant's safety, obtaining informed consent or compliance to the study procedures * Evidence of active mucosal or internal bleeding * Current unstable liver or biliary disease per investigator assessment defined by the presence of ascites, encephalopathy, coagulopathy, hypoalbuminemia, esophageal or gastric varices, persistent jaundice, or cirrhosis. Note: Stable chronic liver disease (including Gilbert's syndrome or asymptomatic gallstones) or hepatobiliary involvement of malignancy is acceptable if participant otherwise meets entry criteria * Participants with previous or concurrent malignancies other than multiple myeloma are excluded, unless the prior malignancy has been considered medically stable for \> 2 years. The participant must not be receiving active therapy, other than hormonal therapy for this disease. NOTE: Participants with curatively treated nonmelanoma skin cancer are allowed without a 2-year restriction. * Evidence of cardiovascular risk, including any of the following: * Evidence of current clinically significant untreated arrhythmias, including clinically significant electrocardiogram (ECG) abnormalities including 2nd degree (Mobitz type II) or 3rd degree atrioventricular (AV) block * History of myocardial infarction (=\< 6 months), acute coronary syndromes (including unstable angina), coronary angioplasty, or stenting or bypass grafting within 12 weeks of screening * Class III or IV heart failure as defined by the New York Heart Association functional classification system \[NYHA, 1994\] * Uncontrolled hypertension * Known immediate or delayed hypersensitivity reaction or idiosyncratic reaction to drugs chemically related to belantamab mafodotin, or any of the com