Donenberg Phillip B. 4

What Happened
Phillip B. Donenberg, a director of Sensei Biotherapeutics (SNSE), received a supplemental option grant of 23,100 shares on April 10, 2026. The grant was reported on a Form 4 filed April 14, 2026. The award was recorded at $0.00 (derivative grant) and is part of his non-employee director compensation rather than an open-market purchase or sale.

Key Details

• Transaction date: April 10, 2026; Form 4 filed April 14, 2026 (timely).
• Transaction type: Grant/award of stock options (derivative).
• Shares/options granted: 23,100 supplemental shares; combined with a prior February 2026 grant of 1,900 shares, this aligns the total initial director option grant to 25,000 shares (per amended policy).
• Price recorded: $0.00 (award/option grant).
• Vesting: Options vest in 36 equal monthly installments over three years; fully vested on April 10, 2029, subject to continued service.
• Shares owned after transaction: Not specified in the filing.
• Footnotes: F1 explains this is a supplemental grant to meet the amended director comp policy; F2 details the monthly 3-year vesting schedule.
• Remarks: Exhibit 24 (Power of Attorney) attached.

Context
This was a compensatory option award to a non-employee director under an amended director compensation policy (initial director grant set to 25,000 shares). It is a derivative grant that vests over time and does not represent an immediate purchase or sale of common stock. Such routine director awards are common and reflect compensation, not necessarily a personal trading signal.