Cabaletta Bio, Inc. SEC Filings

Cabaletta Bio, Inc. filed an 8-K announcing it released financial results for the third quarter ended September 30, 2025. The press release detailing these results was furnished as Exhibit 99.1.

The company stated that the information in Item 2.02, including Exhibit 99.1, is being furnished and is not deemed “filed” under Section 18 of the Exchange Act, nor incorporated by reference into Securities Act or Exchange Act filings except as specifically referenced. Cabaletta Bio’s common stock trades on the Nasdaq Global Select Market under the symbol CABA.

Cabaletta Bio reported an administrative update. The company filed an 8-K stating it posted an updated corporate presentation on October 29, 2025, available on the Investors & Media section of its website. The presentation is attached as Exhibit 99.1 and incorporated by reference. The filing is presented under Item 8.01 (Other Events) with related exhibits listed under Item 9.01(d).

Cabaletta Bio (CABA) furnished new rese‑cel clinical data and development updates across RESET‑Myositis, RESET‑SSc and RESET‑SLE, aligned to an ACR Convergence 2025 data cut as of September 11, 2025.

In RESET‑Myositis, all 4 DM/ASyS patients who met registrational criteria with sufficient follow‑up achieved immunomodulatory‑free TIS moderate or major improvement at week 16; safety included 4 of 13 with grade 1 CRS and no ICANS. The company will initiate a DM/ASyS registrational cohort enrolling 14 patients with a 16‑week primary endpoint, with enrollment starting this quarter. In IMNM, 2 of 4 with sufficient follow‑up achieved TIS at week 24 and additional Phase 1/2 enrollment is planned.

In RESET‑SSc, 4 of 4 patients with at least 3 months’ follow‑up achieved an rCRISS‑25 response off immunomodulators and steroids; low‑grade CRS occurred in three patients and one previously reported grade 3 ICANS event. In RESET‑SLE (n=9), three of four SLE patients achieved DORIS and renal responses were seen in lupus nephritis; all nine were off immunomodulators at cut‑off, with a median 8‑point SLEDAI‑2K reduction. A no‑preconditioning, weight‑based dose cohort will be added to RESET‑SLE, with initial data anticipated in 2026.

Cabaletta Bio (CABA) filed a Form 3 as an initial statement of beneficial ownership for its Chief Commercial Officer. The filing, effective as of 10/13/2025, states that no securities are beneficially owned. An Exhibit 24 Power of Attorney is included, and the document is signed by an attorney-in-fact.

This is a routine administrative disclosure noting the officer’s current ownership status at the time of joining or becoming subject to reporting.

Cabaletta Bio (CABA) disclosed a Form 4 showing its Chief Commercial Officer received a grant of stock options to purchase 275,000 shares at an exercise price of $2.49 on October 13, 2025.

The option was granted under the company’s 2025 Inducement Plan pursuant to NASDAQ Listing Rule 5635(c)(4). It vests with 25% on October 13, 2026, and the remainder in twelve substantially equal quarterly installments thereafter, subject to continued service. The option expires on October 12, 2035. Following the grant, the reporting person holds 275,000 derivative securities directly.

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.

Alyeska entities and Anand Parekh report shared beneficial ownership of 8,904,367 shares of Cabaletta Bio common stock, representing 9.9% of the outstanding class. The reported position reflects 4,800,000 directly held shares plus warrants exercisable only to the extent permitted under their terms so that post-exercise ownership does not exceed 9.9% of the company's outstanding common stock. The filing notes the warrant cap limits actual exercisable shares to 4,104,367 under the agreement and that the percentage calculation uses the issuer's prospectus share count of 89,943,101. The reporting parties filed a joint statement and certify the holdings are in the ordinary course of business.

Cormorant Asset Management, LP and Bihua Chen reported beneficial ownership of 5,000,000 shares of Cabaletta Bio common stock, equal to 5.47% of the outstanding class. The filing attributes sole voting and dispositive power of these shares as 0 and shared voting and dispositive power as 5,000,000. The shares are held by the Cormorant Funds and the filing identifies Cormorant Global Healthcare Master Fund, LP as having rights to more than 5% of the referenced shares. The ownership percentage is calculated using 91,465,233 shares outstanding as reported as of August 1, 2025. The filers certify the shares were acquired and are held in the ordinary course of business and not for the purpose of changing control, and they submitted a joint filing statement accepting responsibility for their portions of the disclosure.