Single-arm Study of IgPro20 in Adults With Secondary Immune Deficiencies Due to Hematologic Malignancies Treated With B-cell Targeting Chimeric Antigen Receptor T-cell and T-cell Redirecting Therapies

• IgPro20 (Biological), also known as Immune Globulin Subcutaneous (Human) 20% Liquid: IgPro20 infusion administered SC.

Primary outcomes

• Number of Serious Bacterial Infections (SBIs) per Participant [Up to Month 12]: The SBIs includes: bacteremia / sepsis, bacterial meningitis, osteomyelitis / septic arthritis, bacterial pneumonia, and visceral abscess.

Secondary outcomes

• Number of Infections per Participant [Up to Month 12]
• Number of Common Terminology Criteria for Adverse Events (CTCAE) >= Grade 3 Infections per Participant [Up to Month 12]: As per CTCAE, Grade 3 is defined as Severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; limiting self care activities of daily living (self-care activities of daily living refer to bathing, dressing and undressing, feeding self, using the toilet, taking medications, and not bedridden). Grade 4: Life-threatening consequences; urgent intervention indicated and Grade 5: Death related to adverse event. Infections of CTCAE Grade 3 or worse will be reported.
• Number of Days Hospitalized due to Infections [Up to Month 12]
• Number of Days With Anti-infectives Use [Up to Month 12]
• Number of Infection-related Deaths and Complications [Up to Month 12]
• Number of Infection-related Requirement for Intravenous (IV) Therapy [Up to Month 12]
• Number of Infection-related Requirement for Hospitalization per Participant [Up to Month 12]
• Number of Participants with Treatment-emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs), Adverse Events of Special Interest (AESIs), Infusion Site Reaction and Other Local Reactions [Up to Month 12]: In this study, thromboembolic events are treated as AESIs. The following 3 narrow standardized Medical Dictionary for Regulatory Activities (MedDRA) queries are used for TEE evaluation: * Embolic and thrombotic events, arterial * Embolic and thrombotic events, venous * Embolic and thrombotic events, vessel type unspecified, and mixed arterial and venous.
• Trough Concentrations of Serum IgG [Up to Week 56]
• Area Under the Serum Concentration Time Curve (AUC) for IgG From Timepoint Zero to tau (AUC[0-t]) [Before IgPro20 dosing at Week 52 and up to Week 54 (after the last dose of IgPro20)]
• Maximal Serum Concentration (Cmax) of IgG [Before IgPro20 dosing at Week 52 and up to Week 54 (after the last dose of IgPro20)]
• Time to Maximal Serum Concentration (Tmax) of IgG [Before IgPro20 dosing at Week 52 and up to Week 54 (after the last dose of IgPro20)]

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Participants greater than or equal to (≥) 18 years of age at the time of providing written informed consent.
* Confirmed diagnosis of B-cell hematologic malignancy (ie, Multiple myeloma \[MM\], Chronic lymphocytic leukemia \[CLL\], Non-Hodgkin lymphoma \[NHL\], or BALL) according to applicable diagnostic criteria.
* Participants treated with Chimeric antigen receptor T-cell (CAR T-cell) therapy or TCE BsAb and are:

  1. At least 2 months after receipt of an approved CAR T-cell therapy for the B-cell hematologic malignancy at the time of Screening, or
  2. At least 1 month after initiation of an approved TCE BsAb therapy for the B-cell hematologic malignancy at the time of Screening and expected to continue with the therapy.
* Documented partial or complete response to CAR T-cell or TCE BsAb therapy based on applicable response criteria at the time of Screening:

  1. CLL based on International Workshop on Chronic Lymphocytic Leukemia response criteria
  2. MM based on International Myeloma Working Group response criteria
  3. NHL based on Lugano Classification criteria
  4. B-ALL based on National Comprehensive Cancer Network guidelines
* IgG level (excluding paraprotein, if relevant) at Screening:

If participant has ongoing IgRT (intravenous immunoglobulin \[IVIG\] or subcutaneous immunoglobulin \[SCIG\]) for SID during Screening, then any IgG level at Screening is acceptable for enrollment. Participants with IgG less than (<) 500 milligrams per deciliter (mg/dL) are assigned to the Loading Cohort, participants with IgG ≥ 500 mg/dL are assigned to the Maintenance-only Cohort.

* IgG level (excluding paraprotein, if relevant) at Screening:

If participant does not have ongoing IgRT (IVIG for > 8 weeks or SCIG for > 2 weeks) for SID during Screening and are not expected to receive IgRT during Screening, then IgG < 500 mg/dL is required for enrollment (participant is assigned to the Loading Cohort)

Exclusion Criteria:

* Documented history of diseases for which IgRT may be indicated: primary immune deficiency, chronic inflammatory demyelinating polyneuropathy, Guillain-Barré syndrome, immune thrombocytopenia, Kawasaki disease, Lambert-Eaton myasthenic syndrome, multifocal motor neuropathy, myasthenia gravis, stiff person syndrome, solid organ transplant, and rejection prior to Screening.
* History of thromboembolic event (TEE) within 6 months before Screening.
* Eastern Cooperative Oncology Group performance status > 1.
* Presence of any systemic active infection at Screening.
* Participants on any prohibited therapies, including anti-infective treatments.
* Absolute neutrophil count < 1 × 10*9/L (Common Terminology Criteria for Adverse Events \[CTCAE\] Grade 3 or worse), unless proven to be due to the underlying disease and raised above the limit by granulocyte colony-stimulating factor.
* Concurrent participation in other interventional clinical studies. Note: a participant may be enrolled if their participation in the other study will not jeopardize their safety and / or the scientific validity of this study (eg, an observational study, a long-term safety follow-up of an interventional study, diagnostic device studies, phase 4 studies with medicines used within their approved indication); the investigator may consult with the medical monitor.