Glofitamab Prior to CAR-T Cell Therapy
Glofitamab should NOT be given prior to CAR-T cell therapy, as it is a bispecific antibody targeting CD20 that could theoretically impair CAR-T cell efficacy and is not indicated in this sequence.
Rationale Based on Guidelines and Evidence
Guideline Recommendations on Prior Targeted Therapies
The 2022 EBMT/EHA guidelines explicitly address prior treatments directed toward the antigenic target of CAR-T therapy 1. Prior treatment with bispecific antibodies (like glofitamab) is listed as "not a contraindication" to CAR-T, BUT this refers to patients who have ALREADY received these agents and are NOW being considered for CAR-T. The guidelines specifically note:
- Antigen-negative escape should be excluded at relapse post-targeted therapy before proceeding to CAR-T, especially in B-cell ALL
- Prior treatment with blinatumomab (another bispecific antibody) may impair CAR-T efficacy in B-ALL
- Reduced CD19 expression may not decrease anti-CD19 CAR-T efficacy in B-ALL, but this varies by target
The Correct Treatment Sequence
The evidence overwhelmingly supports the opposite sequence: glofitamab AFTER CAR-T failure, not before:
- Glofitamab is FDA-approved for patients who have received 2 or more prior treatments 2, and multiple studies demonstrate its efficacy specifically in the post-CAR-T setting 3, 4, 5
- A phase 2 study showed glofitamab achieved 76.1% overall response rate and 45.7% complete response rate in patients who failed CAR-T therapy 3
- Real-world data from 70 patients showed 47% overall response rate with glofitamab after CAR-T (71% had prior CAR-T) 6
Why Glofitamab Before CAR-T Is Problematic
Theoretical concerns about giving glofitamab before CAR-T include:
- Target antigen modulation: Glofitamab causes rapid B-cell depletion (86.5% of patients had undetectable B cells by Cycle 1 Day 7) 2. This could reduce the target antigen availability for subsequent CAR-T cells
- T-cell exhaustion: Glofitamab activates and engages T cells extensively. Pre-exhausting the T-cell compartment before leukapheresis could compromise the quality of collected T cells for CAR-T manufacturing
- Timing of leukapheresis: The guidelines recommend specific washout periods before leukapheresis to ensure adequate T-cell quality 1. No established washout period exists for glofitamab before CAR-T
Bridging Therapy Considerations
If disease control is needed between leukapheresis and CAR-T infusion (bridging therapy), the guidelines recommend 1:
- Bridging therapy should be administered in the 4-6 weeks between leukapheresis and CAR-T administration
- Patient-specific recommendations should consider response to prior therapy and tumor burden
- However, glofitamab is not mentioned as a standard bridging option, and its use would require careful consideration given the lack of data
Clinical Bottom Line
Do not use glofitamab before CAR-T therapy. The established and evidence-based sequence is:
- CAR-T therapy as indicated (after 2+ prior lines for DLBCL)
- If CAR-T fails → Consider glofitamab as salvage therapy
If you need bridging therapy before CAR-T, use conventional chemotherapy regimens with established washout periods 1, not bispecific antibodies that could compromise T-cell fitness or antigen expression.
Common Pitfall: Assuming that because glofitamab works after CAR-T, it would be safe before CAR-T. The biology and timing matter critically—T-cell quality at leukapheresis and target antigen preservation are essential for CAR-T success.