3 Key Takeaways
Plain English Summary- 01Core Finding
Primary end points were the change from baseline to week 16 in the timed 25-ft walk (T25FW) and safety.
- 02Study Evidence
Tested in a early human trial (27 patients) at the Phase I/II stage.
- 03Practical Meaning
Early-stage human studies — dosing, durability, and rare side effects still require Phase III confirmation.
What This Means for You
In this nonrandomized clinical trial, a single dose of mivocabtagene autoleucel resulted in immunotherapy-free remissions with a consistent, well-tolerated safety profile, demonstrating a highly effective therapy in antibody-positive SPS with the potential for durable remissions. Long-term follow-up is ongoing.
The Discovery
To evaluate the efficacy (real-world effectiveness in the trial) and safety of mivocabtagene autoleucel in adult SPS.
This pivotal, single-arm, open-label, nonrandomized Phase 2 study enrolled participants from September 2024 to May 2025 at 3 US sites. Individuals aged 18 to 75 years with antibody-positive SPS and inadequate response to immunomodulatory/immunosuppressive therapies as determined by investigators were included.
Primary end points were the change from baseline to week 16 in the timed 25-ft walk (T25FW) and safety. Secondary end points were modified Rankin Scale score, Distribution of Stiffness Index score, Heightened Sensitivity Scale score, and Hauser Ambulation Index score. Exploratory end points included pharmacokinetic and pharmacodynamic assessments and biomarkers.
Of 27 patients enrolled, 26 (median [range] age, 56.0 [32.0-73.0] years; 16 [61.5%] female) were treated. Median (range) follow-up was 6.5 (4.4-12.2) months. The primary efficacy (real-world effectiveness in the trial) end point was met, with significant week 16 improvement from baseline in T25FW of a mean of -7.69 seconds (SD, 10.03; 95% CI, -11.74 to -3.64; P <.001) and a median (IQR) of -4.8 (-11.9 to -2.5) seconds (a clinically meaningful level median improvement); improvement was sustained (median, 44.4%) among 16 of 26 patients who reached the 24-week time point. All secondary efficacy end points showed significant week 16 improvements from baseline (modified Rankin Scale score: mean, -0.8 points [SD, 0.86; 95% CI, -1.1 to -0.4; P <.001], Distribution of Stiffness Index score: mean, -1.5 points [SD, 1.75; 95% CI, -2.2 to -0.8; P <.001]; Heightened Sensitivity Scale score: mean, -3.2 points [SD, 2.01; 95% CI, -4.0 to -2.3; P <.001]; Hauser Ambulation Index score: mean, -1.6 points [SD, 1.13; 95% CI, -2.1 to -1.2; P <.001]). The most common grade 3/4 treatment-related adverse event was neutropenia (5/26 patients [19.2%]). Low-grade cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome occurred in 24 of 26 patients (92.3%; 10/26 [38.5%] grade 1; 14/26 [53.8%] grade 2) and 3 of 26 patients (11.5%; all grade 1), respectively; all resolved without sequelae. B-cell depletion and clear changes suggestive of immune reset were observed. At last follow-up, all patients remained free of immunomodulatory therapies for SPS.
How It Works, Simply
This neurology research focuses on antibodies · T cells · Immune response. Researchers evaluated it using an early human trial (27 patients) at the Phase I/II stage of medical research.
3 Key Takeaways
Clinical Takeaways- 01Core Finding
Primary end points were the change from baseline to week 16 in the timed 25-ft walk (T25FW) and safety.
- 02Study Evidence
Tested in a early human trial (27 patients) at the Phase I/II stage.
- 03Practical Meaning
Early-stage human studies — dosing, durability, and rare side effects still require Phase III confirmation.
Key Numbers
Biological Mechanism & Study Design
Study Design & Cohort
Early human trial
Early human trial (27 patients) · Phase I/II
Biological Pathway & Modality
Antibodies · T cells · Immune response
Intervention: Mivocabtagene Autoleucel CD19 Chimeric Antigen Receptor T-Cell Therapy
Experimental Findings & Endpoints
To evaluate the efficacy and safety of mivocabtagene autoleucel in adult SPS.
This pivotal, single-arm, open-label, nonrandomized Phase 2 study enrolled participants from September 2024 to May 2025 at 3 US sites. Individuals aged 18 to 75 years with antibody-positive SPS and inadequate response to immunomodulatory/immunosuppressive therapies as determined by investigators were included.
Primary end points were the change from baseline to week 16 in the timed 25-ft walk (T25FW) and safety. Secondary end points were modified Rankin Scale score, Distribution of Stiffness Index score, Heightened Sensitivity Scale score, and Hauser Ambulation Index score.
Exploratory end points included pharmacokinetic and pharmacodynamic assessments and biomarkers.
Of 27 patients enrolled, 26 (median [range] age, 56.0 [32.0-73.0] years; 16 [61.5%] female) were treated. Median (range) follow-up was 6.5 (4.4-12.2) months.
The primary efficacy end point was met, with significant week 16 improvement from baseline in T25FW of a mean of -7.69 seconds (SD, 10.03; 95% CI, -11.74 to -3.64; P <.001) and a median (IQR) of -4.8 (-11.9 to -2.5) seconds (a clinically meaningful level median improvement); improvement was sustained (median, 44.4%) among 16 of 26 patients who reached the 24-week time point. All secondary efficacy end points showed significant week 16 improvements from baseline (modified Rankin Scale score: mean, -0.8 points [SD, 0.86; 95% CI, -1.1 to -0.4; P <.001], Distribution of Stiffness Index score: mean, -1.5 points [SD, 1.75; 95% CI, -2.2 to -0.8; P <.001]; Heightened Sensitivity Scale score: mean, -3.2 points [SD, 2.01; 95% CI, -4.0 to -2.3; P <.001]; Hauser Ambulation Index score: mean, -1.6 points [SD, 1.13; 95% CI, -2.1 to -1.2; P <.001]).
The most common grade 3/4 treatment-related adverse event was neutropenia (5/26 patients [19.2%]). Low-grade cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome occurred in 24 of 26 patients (92.3%; 10/26 [38.5%] grade 1; 14/26 [53.8%] grade 2) and 3 of 26 patients (11.5%; all grade 1), respectively; all resolved without sequelae.
B-cell depletion and clear changes suggestive of immune reset were observed. At last follow-up, all patients remained free of immunomodulatory therapies for SPS.
Clinical Translation & Practice Context
In this nonrandomized clinical trial, a single dose of mivocabtagene autoleucel resulted in immunotherapy-free remissions with a consistent, well-tolerated safety profile, demonstrating a highly effective therapy in antibody-positive SPS with the potential for durable remissions.
Long-term follow-up is ongoing.
The Bottom Line · Clinical Pearl
“In this nonrandomized clinical trial, a single dose of mivocabtagene autoleucel resulted in immunotherapy-free remissions with a consistent, well-tolerated safety profile, demonstrating a highly effective therapy in antibody-positive SPS with the potential for durable remissions. Long-term follow-up is ongoing.”
Published in JAMA Neurology · Current Stage: Phase I/II
