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[8-K] Cabaletta Bio, Inc. Reports Material Event

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Cabaletta Bio reported early clinical and translational data for its autologous CAR T candidate rese-cel from three patients. All three showed substantial peripheral B cell depletion within the first month and rapid reductions in disease‑linked autoantibodies in two patients, consistent with deep tissue B cell depletion. Rese-cel had a generally tolerable safety profile: no ICANS was reported, one transient fever consistent with grade 1 cytokine release syndrome occurred, and one patient required a short steroid course for a post‑infusion flare but tapered below baseline by 3 months. Meaningful early clinical responses were seen by Pemphigus Disease Area Index (PDAI) scores: Patient 1 improved from 24 to 10 at 4 months, Patient 2 from 83 to 3 at 3 months, and Patient 3 from 22 to 2 at 1 month.

Cabaletta Bio ha riportato dati clinici iniziali e translazionali per il suo candidato CAR T autologo rese-cel da tre pazienti. Tutti e tre hanno mostrato una sostanziale deplezione periferica di cellule B entro il primo mese e rapidi cali degli autoanticorpi legati alla malattia in due pazienti, coerenti con una marcata deplezione delle cellule B nei tessuti. Rese-cel ha presentato, in generale, un profilo di sicurezza tollerabile: nessun ICANS è stato riportato, una febbre transitoria coerente con una sindrome da rilascio di citochine di grado 1, e un paziente ha richiesto un breve ciclo di steroidi per una riacutizzazione post-infusione ma si è scalato al di sotto del valore basale entro 3 mesi. Risposte cliniche iniziali significative sono state osservate secondo i punteggi di Pemphigus Disease Area Index (PDAI): Paziente 1 è migliorato da 24 a 10 a 4 mesi, Paziente 2 da 83 a 3 a 3 mesi, e Paziente 3 da 22 a 2 a 1 mese.

Cabaletta Bio informó datos clínicos temprano y translacionales para su candidato CAR T autólogo rese-cel de tres pacientes. Los tres mostraron una eliminación sustancial de células B periféricas dentro del primer mes y reducciones rápidas en autoanticuerpos ligados a la enfermedad en dos pacientes, consistente con una depleción profunda de células B en los tejidos. rese-cel tuvo un perfil de seguridad generalmente tolerable: no se reportó ICANS, se produjo una fiebre transitoria compatible con síndrome de liberación de citocinas de grado 1, y un paciente requirió un breve ciclo de esteroides por una aparición inflamatoria post-infusión pero disminuyó por debajo del nivel basal en 3 meses. Respuestas clínicas tempranas significativas se observaron según los puntajes PDAI (Pemphigus Disease Area Index): Paciente 1 mejoró de 24 a 10 a 4 meses, Paciente 2 de 83 a 3 a 3 meses, y Paciente 3 de 22 a 2 a 1 mes.

Cabaletta Bio는 자가 CAR T 후보물질 rese-cel에 대한 초기 임상 및 전임상 데이터를 세 명의 환자로부터 보고했습니다. 세 명 모두 첫 달 이내에 말초 B 세포의 상당한 감소를 보였고 질환과 관련된 자가항체가 두 환자에서 빠르게 감소했으며 이는 깊은 조직 B 세포 감소와 일치합니다. rese-cel은 일반적으로 허용 가능한 안전성 프로파일을 보였습니다: ICANS은 보고되지 않았고 한 명의 환자에서 1등급 사이토카인 방출 증후군에 해당하는 발열이 일시적으로 나타났으며 한 명의 환자는 infusion 후 발적을 억제하기 위해 짧은 코르티코스테로이드 치료를 받았지만 3개월 까지 기저선 아래로 점차 감소했습니다. 의미 있는 초기 임상 반응은 PDAI 점수로 보였습니다: 환자 1은 4개월에 24에서 10으로, 환자 2는 3개월에 83에서 3으로, 환자 3은 1개월에 22에서 2로 개선되었습니다.

Cabaletta Bio a publié des données cliniques précoces et translationnelles pour son candidat CAR T autologue rese-cel chez trois patients. Les trois ont montré une déplétion substantielle des cellules B périphériques dans le premier mois et des réductions rapides des auto-anticorps liés à la maladie chez deux patients, compatibles avec une déplétion profonde des cellules B tissulaires. Le rese-cel a eu un profil de sécurité généralement tolérable: aucun ICANS n’a été reporté, une fièvre transitoire compatible avec un syndrome de libération de cytokines de grade 1, et un patient a nécessité une brève cure de stéroïdes pour une poussée post-infusion mais est revenu au-dessous du niveau bas d’ici 3 mois. Des réponses cliniques précoces significatives ont été observées selon l’indice PDAI (Pemphigus Disease Area Index): Patient 1 est passé de 24 à 10 à 4 mois, Patient 2 de 83 à 3 à 3 mois, et Patient 3 de 22 à 2 à 1 mois.

Cabaletta Bio berichtete frühe klinische und translationale Daten zu seinem autologen CAR-T-Kandidaten rese-cel aus drei Patienten. Alle drei zeigten eine deutliche periphere B-Zell-Depletion innerhalb des ersten Monats und rasche Abnahmen krankheitsassoziierter Autoantikörper bei zwei Patienten, was mit einer tiefen Gewebe-B-Zell-Depletion übereinstimmt. Rese-cel hatte ein im Allgemeinen verträgliches Sicherheitsprofil: Es wurde kein ICANS berichtet, es trat eine vorübergehende Fieberreaktion auf, konsistent mit einem Grad-1-Cytokine-Release-Syndrom, und bei einem Patienten war eine kurze Steroidtherapie aufgrund eines postinfusionsbedingten Flairs erforderlich, die aber bis unter den Baseline-Wert bis 3 Monate abgeklungen ist. Bedeutende frühe klinische Reaktionen wurden anhand der PDAI-Werte beobachtet: Patient 1 stieg von 24 auf 10 bei 4 Monate, Patient 2 von 83 auf 3 bei 3 Monate, und Patient 3 von 22 auf 2 bei 1 Monat.

Cabaletta Bio أبلغت عن بيانات سريرية مبكرة ونقلية لمُرشّح CAR T ذاتي المنشأ rese-cel من ثلاث مرضى. أظهر الثلاثة انخفاضاً كبيراً في خلايا B المحيطية خلال الشهر الأول وتراجعات سريعة في الأجسام المضادة الذاتية المرتبطة بالمرض لدى مريضين، بما يتسق مع انخفاض عميق لخلايا B في الأنسجة. rese-cel كان له ملف أمان عام قابل للتحمل: لم يُبلّغ عن ICANS، وظهرت حمى عابرة تتوافق مع متلازمة إطلاق سيتوكينات من الدرجة 1، واحتاج مريض واحد إلى دورة كورتيكوستيرويد قصيرة بسبب تفاقم بعد الحقن لكن تراجع إلى ما دون المستوى الأساسي بحلول 3 أشهر. لوحظت استجابات سريرية مبكرة ذات معنى وفقاً لمؤشر PDAI (Pemphigus Disease Area Index): المريض 1 تحسن من 24 إلى 10 عند 4 أشهر، المريض 2 من 83 إلى 3 عند 3 أشهر، والمريض 3 من 22 إلى 2 عند 1 شهر.

Cabaletta Bio 报告了其自体 CAR T 候选药物 rese-cel 在三名患者中的早期临床和转化数据。三名患者均在第一个月内显示出显著的外周 B 细胞减少,并且在两名患者中疾病相关的自身抗体迅速下降,与深层组织 B 细胞减少一致。rese-cel 的安全性总体可耐受:未报告 ICANS,出现一次与 1 级细胞因子释放综合征相关的短暂发热,一名患者在输注后有炎症反应需要短期口服皮质类固醇治疗,但在 3 个月时降至基线以下。按照 Pemphigus Disease Area Index (PDAI) 指标,出现有意义的早期临床反应:患者1 从 24 改善至 10,时点在 4 个月;患者2 从 83 改善至 3,时点在 3 个月;患者3 从 22 改善至 2,时点在 1 个月

Positive
  • All three patients showed meaningful PDAI score improvements (24→10, 83→3, 22→2).
  • Substantial peripheral B cell depletion occurred within the first month in all patients, with complete depletion in patients 2 and 3.
  • No ICANS was reported, and only one transient grade 1 CRS was observed.
Negative
  • Very small sample size — data from only three patients limits generalizability.
  • One patient required steroids for a post‑infusion flare, indicating disease activity and management needs.
  • Short follow‑up (1–4 months) leaves durability and long‑term safety unaddressed.

Insights

Early signals show biological activity and clinical improvement in three patients.

Translational measures indicate substantial peripheral B cell depletion within the first month and rapid reduction of autoantibodies in two patients, suggesting on‑target pharmacology for rese-cel. The observed BAFF increase remained within ranges seen with preconditioning, consistent with deep B cell clearance in tissue.

The safety observations are limited but notable: no reported ICANS, a single grade 1 CRS, and one steroid‑treated flare that has since reduced below baseline by 3 months. Key near‑term items to watch are durability of B cell depletion, sustained PDAI improvements beyond the reported 1–4 months, and safety in a larger cohort.

Pharmacodynamic markers track with expected CAR T biology, supporting mechanism of action.

All three patients experienced B cell depletion and two achieved complete peripheral depletion, which aligns with effective CAR T engagement of target B cells. The rapid drop in desmoglein autoantibodies in those two patients further supports targeted immune modulation.

Risks include limited sample size and short follow‑up; confirmatory data on tissue B cell recovery, BAFF trajectory, and longer‑term autoantibody suppression over the next 6–12 months will be material for assessing clinical benefit and safety.

Cabaletta Bio ha riportato dati clinici iniziali e translazionali per il suo candidato CAR T autologo rese-cel da tre pazienti. Tutti e tre hanno mostrato una sostanziale deplezione periferica di cellule B entro il primo mese e rapidi cali degli autoanticorpi legati alla malattia in due pazienti, coerenti con una marcata deplezione delle cellule B nei tessuti. Rese-cel ha presentato, in generale, un profilo di sicurezza tollerabile: nessun ICANS è stato riportato, una febbre transitoria coerente con una sindrome da rilascio di citochine di grado 1, e un paziente ha richiesto un breve ciclo di steroidi per una riacutizzazione post-infusione ma si è scalato al di sotto del valore basale entro 3 mesi. Risposte cliniche iniziali significative sono state osservate secondo i punteggi di Pemphigus Disease Area Index (PDAI): Paziente 1 è migliorato da 24 a 10 a 4 mesi, Paziente 2 da 83 a 3 a 3 mesi, e Paziente 3 da 22 a 2 a 1 mese.

Cabaletta Bio informó datos clínicos temprano y translacionales para su candidato CAR T autólogo rese-cel de tres pacientes. Los tres mostraron una eliminación sustancial de células B periféricas dentro del primer mes y reducciones rápidas en autoanticuerpos ligados a la enfermedad en dos pacientes, consistente con una depleción profunda de células B en los tejidos. rese-cel tuvo un perfil de seguridad generalmente tolerable: no se reportó ICANS, se produjo una fiebre transitoria compatible con síndrome de liberación de citocinas de grado 1, y un paciente requirió un breve ciclo de esteroides por una aparición inflamatoria post-infusión pero disminuyó por debajo del nivel basal en 3 meses. Respuestas clínicas tempranas significativas se observaron según los puntajes PDAI (Pemphigus Disease Area Index): Paciente 1 mejoró de 24 a 10 a 4 meses, Paciente 2 de 83 a 3 a 3 meses, y Paciente 3 de 22 a 2 a 1 mes.

Cabaletta Bio는 자가 CAR T 후보물질 rese-cel에 대한 초기 임상 및 전임상 데이터를 세 명의 환자로부터 보고했습니다. 세 명 모두 첫 달 이내에 말초 B 세포의 상당한 감소를 보였고 질환과 관련된 자가항체가 두 환자에서 빠르게 감소했으며 이는 깊은 조직 B 세포 감소와 일치합니다. rese-cel은 일반적으로 허용 가능한 안전성 프로파일을 보였습니다: ICANS은 보고되지 않았고 한 명의 환자에서 1등급 사이토카인 방출 증후군에 해당하는 발열이 일시적으로 나타났으며 한 명의 환자는 infusion 후 발적을 억제하기 위해 짧은 코르티코스테로이드 치료를 받았지만 3개월 까지 기저선 아래로 점차 감소했습니다. 의미 있는 초기 임상 반응은 PDAI 점수로 보였습니다: 환자 1은 4개월에 24에서 10으로, 환자 2는 3개월에 83에서 3으로, 환자 3은 1개월에 22에서 2로 개선되었습니다.

Cabaletta Bio a publié des données cliniques précoces et translationnelles pour son candidat CAR T autologue rese-cel chez trois patients. Les trois ont montré une déplétion substantielle des cellules B périphériques dans le premier mois et des réductions rapides des auto-anticorps liés à la maladie chez deux patients, compatibles avec une déplétion profonde des cellules B tissulaires. Le rese-cel a eu un profil de sécurité généralement tolérable: aucun ICANS n’a été reporté, une fièvre transitoire compatible avec un syndrome de libération de cytokines de grade 1, et un patient a nécessité une brève cure de stéroïdes pour une poussée post-infusion mais est revenu au-dessous du niveau bas d’ici 3 mois. Des réponses cliniques précoces significatives ont été observées selon l’indice PDAI (Pemphigus Disease Area Index): Patient 1 est passé de 24 à 10 à 4 mois, Patient 2 de 83 à 3 à 3 mois, et Patient 3 de 22 à 2 à 1 mois.

Cabaletta Bio berichtete frühe klinische und translationale Daten zu seinem autologen CAR-T-Kandidaten rese-cel aus drei Patienten. Alle drei zeigten eine deutliche periphere B-Zell-Depletion innerhalb des ersten Monats und rasche Abnahmen krankheitsassoziierter Autoantikörper bei zwei Patienten, was mit einer tiefen Gewebe-B-Zell-Depletion übereinstimmt. Rese-cel hatte ein im Allgemeinen verträgliches Sicherheitsprofil: Es wurde kein ICANS berichtet, es trat eine vorübergehende Fieberreaktion auf, konsistent mit einem Grad-1-Cytokine-Release-Syndrom, und bei einem Patienten war eine kurze Steroidtherapie aufgrund eines postinfusionsbedingten Flairs erforderlich, die aber bis unter den Baseline-Wert bis 3 Monate abgeklungen ist. Bedeutende frühe klinische Reaktionen wurden anhand der PDAI-Werte beobachtet: Patient 1 stieg von 24 auf 10 bei 4 Monate, Patient 2 von 83 auf 3 bei 3 Monate, und Patient 3 von 22 auf 2 bei 1 Monat.

false000175913800017591382025-10-092025-10-09

 

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

 

FORM 8-K

 

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 09, 2025

 

 

CABALETTA BIO, INC.

(Exact name of Registrant as Specified in Its Charter)

 

 

Delaware

001-39103

82-1685768

(State or Other Jurisdiction
of Incorporation)

(Commission File Number)

(IRS Employer
Identification No.)

 

 

 

 

 

2929 Arch Street

Suite 600

 

Philadelphia, Pennsylvania

 

19104

(Address of Principal Executive Offices)

 

(Zip Code)

 

Registrant’s Telephone Number, Including Area Code: (267) 759-3100

 

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

 

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:


Title of each class

 

Trading
Symbol(s)

 


Name of each exchange on which registered

Common Stock, par value $0.00001 per share

 

CABA

 

The Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.

 


Item 7.01 Regulation FD Disclosure.

On October 9, 2025, Cabaletta Bio, Inc. (“Cabaletta” or the “Company”) issued a press release reporting new clinical and translational data from the ongoing RESET-PVtrial evaluating rese-cel (resecabtagene autoleucel, formerly known as CABA-201) (the “Press Release”). A copy of the Press Release is furnished herewith as Exhibit 99.1 to this Current Report on Form 8-K.

The information contained in Item 7.01 of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed to be “filed” for the purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section and shall not be incorporated by reference in any filing under the Securities Act or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

Item 8.01 Other Events.

On October 9, 2025, the Company posted to the “Investors & Media” section of the Company’s website at www.cabalettabio.com an updated corporate presentation (the “Corporate Presentation”). A copy of the Corporate Presentation is attached hereto as Exhibit 99.2 to this Current Report on Form 8-K and incorporated herein by reference.

Cabaletta is presenting new clinical and translational data from three evaluable patients who were dosed with rese-cel in the RESET-PV trial in a late-breaking clinical oral presentation at the 2025 European Society of Gene & Cell Therapy (ESGCT) Annual Congress. The RESET-PV trial is the first study within Cabaletta’s RESET clinical development program to evaluate rese-cel without the use of cyclophosphamide and fludarabine as preconditioning agents.

Key clinical and translational insights from these patients, as of the data cut-off date of September 11, 2025, include:

Translational Profile: Rese-cel exhibited similar CAR T cell expansion and contraction kinetics relative to translational data reported from other RESET trials with preconditioning. All three patients experienced substantial depletion of B cells within the first month post-infusion, with patients 2 and 3 achieving complete peripheral B cell depletion. In these two patients, rapid reduction in autoantibodies to desmoglein was observed and the increase in peak B cell activating factor (BAFF) was within the range of patients dosed with rese-cel plus preconditioning from pre-infusion through the latest follow-up, suggestive of deep B cell depletion in the tissue.
Safety Profile: Rese-cel was generally well tolerated with no immune effector cell-associated neurotoxicity syndrome (ICANS) reported. After infusion, patient 1 experienced transient fever (grade 1 cytokine release syndrome). Patient 2 required a course of steroids for a disease flare in the first two weeks following infusion after discontinuing immunomodulators. This steroid course was less intense than a previous course that was administered for a flare prior to infusion where limited impact on disease was observed. The patient has tapered the steroid dose to below the pre-infusion baseline dose at 3 months post-infusion.
Clinical Profile: Meaningful early clinical responses were observed in all three patients starting in the first month post-infusion based on Pemphigus Disease Area Index (PDAI) score for skin, scalp and mucosal surfaces. From baseline to latest follow-up, PDAI activity scores improved as follows:
o
Patient 1 (4 mo): 24 to 10
o
Patient 2 (3 mo): 83 to 3
o
Patient 3 (1 mo): 22 to 2

PDAI activity scores have formed the basis for the most recent regulatory approval in PV. Total PDAI scores were also reported to be consistent with the PDAI activity scores, including improvement in the PDAI damage scores, in the late-breaking clinical oral presentation. PDAI improvements were most significant in the two patients who experienced complete B cell depletion. All three patients remain off immunomodulators as of the data cut-off.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

 

 

 

99.1

 

Press Release issued by the registrant on October 9, 2025, furnished herewith.

 

 

 

99.2

 

Cabaletta Bio, Inc. Corporate Presentation, dated October 2025, filed herewith.

 

 

104

 

Cover Page Interactive Data File (embedded within the Inline XBRL Document).

 


SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

 

CABALETTA BIO, INC.

 

 

 

 

Date: October 9, 2025

By:

/s/ Steven Nichtberger

Steven Nichtberger

Chief Executive Officer and President

(Principal Executive Officer)

 


FAQ

What early clinical results did Cabaletta (CABA) report for rese-cel?

All three patients showed meaningful PDAI score improvements: Patient 1 24→10 at 4 months, Patient 2 83→3 at 3 months, Patient 3 22→2 at 1 month.

Were there safety concerns in the CABA rese-cel data?

Rese-cel was generally well tolerated: no ICANS reported, one transient grade 1 CRS, and one patient needed a steroid course for a flare but tapered below baseline by 3 months.

Did rese-cel affect B cells and autoantibodies in the CABA report?

Yes. All three patients experienced substantial peripheral B cell depletion within the first month; Patients 2 and 3 achieved complete depletion and showed rapid reduction in desmoglein autoantibodies.

How mature is the data Cabaletta presented for CABA rese-cel?

The dataset is early and limited to three patients with follow‑up ranging from 1 to 4 months, so longer follow‑up and larger cohorts are needed to confirm durability and safety.
Cabaletta Bio, Inc.

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