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

A Phase 3, Prospective, Open-label, Multicenter, Single-arm Study to Investigate the Efficacy, Safety, and Pharmacokinetics of IgPro20 in Subjects With Secondary Immune Deficiency Due to Hematologic Malignancies Treated With B-cell Targeting Chimeric Antigen Receptor T-cell and T-cell Redirecting Therapies

This is a prospective, multicenter, open-label, single-arm study to assess the efficacy, safety, and pharmacokinetics (PK) of IgPro20 in adults with hematologic malignancies treated with B-cell targeting Chimeric antigen receptor T-cell (CAR T-cell) and T-cell redirecting therapies (such as T-cell engager bispecific antibody [TCE BsAb] therapy). The primary objective is to demonstrate that true annualized rate of serious bacterial infection (SBIs) is less than (<) 1.0.

This study includes two cohorts:

1. Loading Cohort: Participants with serum immunoglobulin G (IgG) < 500 milligrams per deciliter (mg/dL) at Screening, with or without ongoing immunoglobulin replacement therapy (IgRT) during Screening, who must have received five doses of IgPro20 during the Initial Treatment Period.
2. Maintenance-only Cohort: Participants with serum IgG greater than or equal to (≥) 500 mg/dL and ongoing IgRT at Screening, who must have received one dose of IgPro20 during the Initial Treatment Period.

Study Overview

• Status: Not yet recruiting
• Conditions: Secondary Immune Deficiency
• Intervention / Treatment: Biological: IgPro20

• Study Type: Interventional
• Enrollment (Estimated): 63
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Trial Registration Coordinator; Phone Number: +16108784697; Email: clinicaltrials@cslbehring.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: IgPro20; In the loading cohort, participants will receive a loading dose of IgPro20 subcutaneously (SC) once daily for five consecutive days during the first week (Initial Treatment Period), followed by SC infusion weekly dosing for a total treatment duration of 52 weeks. In the maintenance-only cohort, participants will receive weekly doses of IgPro20 SC infusion for a total treatment duration of 52 weeks.

Biological: IgPro20; IgPro20 infusion administered SC.; Other Names: Immune Globulin Subcutaneous (Human) 20% Liquid

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Serious Bacterial Infections (SBIs) per Participant	The SBIs includes: bacteremia / sepsis, bacterial meningitis, osteomyelitis / septic arthritis, bacterial pneumonia, and visceral abscess.	Up to Month 12

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Infections per Participant		Up to Month 12
Number of Common Terminology Criteria for Adverse Events (CTCAE) >= Grade 3 Infections per Participant	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.	Up to Month 12
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	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.	Up to Month 12
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)

Collaborators and Investigators

• Sponsor: CSL Behring

Study record dates

Study Major Dates

• Study Start (Estimated): July 25, 2026
• Primary Completion (Estimated): February 16, 2029
• Study Completion (Estimated): February 16, 2029

Study Registration Dates

• First Submitted: June 10, 2026
• First Submitted That Met QC Criteria: June 10, 2026
• First Posted (Actual): June 15, 2026

Study Record Updates

• Last Update Posted (Actual): June 15, 2026
• Last Update Submitted That Met QC Criteria: June 10, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Chronic lymphocytic leukemia (CLL); Small lymphocytic lymphoma (SLL); Hematologic Malignancies; Hypogammaglobulinemia; Multiple myeloma (MM); Non-Hodgkin lymphomas (NHL); B-cell acute lymphoblastic leukemia (B-ALL); T-cell engager bispecific antibody (TCE BsAb) therapy; Lowered serum immunoglobulin levels
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Pathologic Processes; Neoplasms by Site; Neoplasms; Chronic Disease; Disease Attributes; Immune System Diseases; Infections; Virus Diseases; Neoplasms by Histologic Type; Hematologic Diseases; Immunologic Deficiency Syndromes; DNA Virus Infections; Lymphatic Diseases; Lymphoproliferative Disorders; Immunoproliferative Disorders; Lymphoma, Non-Hodgkin; Leukemia, B-Cell; Lymphoma, B-Cell; Lymphoma; Neoplasms, Plasma Cell; Hemostatic Disorders; Paraproteinemias; Blood Protein Disorders; Hemorrhagic Disorders; Leukemia, Lymphoid; Leukemia; Epstein-Barr Virus Infections; Herpesviridae Infections; Tumor Virus Infections; Pathological Conditions, Signs and Symptoms; Hemic and Lymphatic Diseases; Hematologic Neoplasms; Leukemia, Lymphocytic, Chronic, B-Cell; Multiple Myeloma; Burkitt Lymphoma; Agammaglobulinemia; Amino Acids, Peptides, and Proteins; Proteins; Therapeutics; Drug Therapy; Immunoglobulins; Immunoproteins; Blood Proteins; Serum Globulins; Globulins; gamma-Globulins; Fluid Therapy; Hizentra
• Other Study ID Numbers: IgPro20_3013; 2026-525626-38-00 (Registry Identifier: EU CT Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: CSL will consider on a case-by-case basis requests to share Individual Patient Data (IPD) with external bona-fide, qualified scientific and medical researchers. For information on the process and requirements for submitting a voluntary data sharing request for IPD, please contact CSL at clinicaltrials@cslbehring.com.
• IPD Sharing Time Frame: Requests for IPD will generally be considered once review by major regulatory authorities (ie FDA, EMA) is complete and the primary publication is available.

IPD Sharing Access Criteria

Proposed research should seek to answer a previously unanswered important medical or scientific question.

Applicable country specific privacy and other laws and regulations will be considered and may prevent sharing of IPD.

If the request is approved and the researcher has executed an appropriate data sharing agreement, IPD that has been appropriately anonymized will be available.

• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No