Resecel
Rese-cel (resecabtagene autoleucel; formerly CABA-201) is a fully human, autologous 4-1BB CD19 CAR-T being studied as a “one-time” immune-reset strategy in idiopathic inflammatory myopathies (IIM).
The lead program is RESET-Myositis (Phase 1/2, open-label) with independent adult cohorts in dermatomyositis (DM), antisynthetase syndrome (ASyS), and immune-mediated necrotizing myopathy (IMNM) (and a juvenile cohort). Protocol descriptions report: age 18–75, refractory IIM per 2017 EULAR/ACR criteria, myositis-specific autoantibody requirement, muscle weakness thresholds, and “moderate” activity in ≥2 core set measures; patients receive a single weight-based infusion of 1×10⁶ CAR-T cells/kg after fludarabine + cyclophosphamide preconditioning, with discontinuation of non-glucocorticoid immunomodulators before infusion. [1–3]
Preliminary efficacy/safety signals have been presented via conference abstract and company-reported data cuts. In the EULAR 2025 update (data cut May 6, 2025 for myositis), 7/8 myositis patients achieved a clinically meaningful *Total Improvement Score (TIS) *response off immunomodulators (while off or tapering steroids), including all 4/4 DM+ASyS (with 3/4 major TIS) and 3/4 IMNM showing “clinically meaningful drug-free responses.” Safety in this small set included 4/8 with grade 1 CRS (fever) and no ICANS. Translationally, peak rese-cel expansion was around ~2 weeks, with rapid, transient peripheral B-cell depletion in the first month and repopulation beginning around ~2 months. [4] The ACR 2025 abstract also reports CD19+CD20+ B cells reduced to undetectable by ~day 14 through the first month, with reconstitution as early as 8–12 weeks in some patients and a predominantly transitional/naïve phenotype on re-emergence. [1]
By ACR Convergence 2025, Cabaletta stated it was presenting “complete” adult Phase 1/2 datasets from 6 DM/ASyS and 6 IMNM patients (plus 1 juvenile patient), and noted that all DM/ASyS patients meeting key registrational-cohort inclusion criteria with sufficient follow-up achieved immunomodulatory-free TIS responses of moderate or major improvement at week 16. [5]
In parallel, the company described FDA-aligned single-arm registrational cohorts (approximately ~15 DM/ASyS and ~15 IMNM) using the same 1×10⁶ cells/kg dose and a TIS-based primary endpoint within 26 weeks, with an RMAT designation and a pooled autoimmune safety database strategy. [6].
For rese-cel (resecabtagene autoleucel; investigational CD19 CAR-T from Cabaletta Bio), the “pre-treatment” in the RESET autoimmune trials has generally meant (A) stopping background immunomodulators, then (B) short lymphodepleting chemo (a.k.a. “preconditioning”), and then CAR-T infusion—except for a cohort exploring no preconditioning.
1) Standard “preconditioning” used in most RESET trials (autoimmune cohorts)
From published trial abstracts describing RESET systemic sclerosis / lupus designs:
- Stop non-glucocorticoid immunosuppressive / immunomodulatory agents by Day −5 (i.e., DMARDs/biologics and other non-steroid immune therapies are held).
- Fludarabine 25 mg/m²/day IV on Days −5, −4, −3
- Cyclophosphamide 1,000 mg/m² IV on Day −3
- Then a single weight-based infusion of rese-cel (often reported as 1×10⁶ CAR-T cells/kg in these cohorts).
That’s the core pharmacologic preparation as described in the autoimmune trial materials (and it’s explicitly described as cyclophosphamide + fludarabine “preconditioning”).
2) “No preconditioning” strategy (selected cohorts)
Cabaletta reported that RESET-PV (pemphigus vulgaris) was the first RESET study to evaluate rese-cel without cyclophosphamide and fludarabine preconditioning (“no preconditioning”), with early translational/clinical data presented in 2025.
Practical interpretation (what you should take away)
- If you mean “what do I actually give before rese-cel?”: in most RESET cohorts it’s CY/FLU lymphodepletion (doses above) + holding non-steroid immunomodulators by Day −5.
- If you mean “is chemo always required for rese-cel?”: not necessarily—there is an active development path using no preconditioning in at least one cohort.
If you tell me which RESET disease cohort you’re asking about (SLE/LN vs myositis vs SSc vs PV vs MG), I’ll map the above into a tight Day −5 → Day 0 medication timeline and highlight what’s typically held vs allowed (especially glucocorticoids).
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References (linked)
1.Wilfong E, Mozaffar T, Naddaf E, et al. RESET-Myositis: Clinical Trial Evaluating Rese-cel (Resecabtagene Autoleucel)… in Idiopathic Inflammatory Myopathies (ACR Convergence 2025 abstract).
https://acrabstracts.org/abstract/reset-myositis-clinical-trial-evaluating-rese-cel-resecabtagene-autoleucel-a-fully-human-autologous-4-1bb-cd19-car-t-cell-therapy-in-idiopathic-inflammatory-myopathies/
2.Vanderbilt Trials Today listing (derived from ClinicalTrials.gov): NCT06154252 / RESET-Myositis (study design, cohorts, preconditioning).
https://vanderbilt.trialstoday.org/trial/NCT06154252
3.UC Irvine Clinical Trials listing: NCT06154252 / RESET-Myositis (eligibility highlights, dates, disease subtypes).
https://clinicaltrials.icts.uci.edu/trial/NCT06154252
4.Cabaletta Bio press release PDF (EULAR 2025 data cut): 7/8 TIS responses; 4/8 grade 1 CRS; no ICANS (June 11, 2025).
5.GlobeNewswire press release: ACR 2025 dataset scope (6 DM/ASyS; 6 IMNM) and week-16 TIS statement (Oct 27, 2025).
https://www.globenewswire.com/news-release/2025/10/27/3174441/0/en/Cabaletta-Bio-Presents-Positive-Clinical-Data-and-Development-Updates-for-Rese-cel-at-ACR-Convergence-2025.html
6.Cabaletta Bio press release PDF: FDA-aligned registrational cohorts (15 each), TIS primary endpoint within 26 weeks; 1×10⁶ cells/kg (May 15, 2025).