Development of CAR NK Cell Lines Selectively Targeting Cancer Cells Expressing Membrane Hsp70.

Area of Science:

• Immunotherapy
• Cellular therapy
• Oncology

Background:

• Chimeric antigen receptor (CAR)-based immunotherapy requires suitable immune cell platforms and tumor-specific antigens for solid tumor treatment.
• Natural killer (NK) cells are promising CAR platforms due to their inherent cytotoxicity, safety, and potential for standardized, off-the-shelf application.

Purpose of the Study:

• To develop and evaluate anti-Hsp70 CAR NK cell lines for targeting solid tumors expressing membrane-bound heat shock protein 70 (mHsp70).

Main Methods:

• Four human NK cell lines (YT, KHYG1, NKL, NK92) were retrovirally transduced with an anti-Hsp70 CAR.
• Computational modeling assessed CAR-mHsp70 binding.
• CAR integration, surface expression, cell viability, activation markers, effector molecule secretion, and target-specific cytotoxicity were evaluated.

Main Results:

• All NK cell lines showed CAR integration and surface expression, but only NKL and NK92 maintained stable expression and viability.
• Anti-Hsp70 CAR NKL and NK92 cells exhibited enhanced activation markers and cytotoxic molecule secretion.
• These CAR NK cells demonstrated robust, specific killing of mHsp70-positive cancer cells while sparing mHsp70-negative cells.

Conclusions:

• NKL and NK92 cells are suitable platforms for developing off-the-shelf CAR NK cell therapies targeting mHsp70-expressing solid tumors.
• Anti-Hsp70 CAR NK cells represent a promising therapeutic strategy for a broad spectrum of solid cancers.