Objective:

Develop and evaluate a tumor-targeted, nonviral platform for generating CAR-expressing immune cells within solid tumors.

Approach:

• Delivery system: Researchers developed R8L-NI@Lipo, a lipoplex incorporating the tumor-penetrating peptide octa-arginine and an O-phospho-L-serine component targeting GRM4.
• Genetic payload: The lipoplex carried plasmid DNA encoding an NKG2D-based CAR and IL-15, with hypoxia-responsive elements intended to limit CAR expression to low-oxygen tumor environments.
• Preclinical evaluation: The platform was assessed for tumor delivery, CAR expression, immune-cell activity, antitumor effects, survival, and safety in mouse breast cancer models.

Key Findings:

• Targeted lipoplexes accumulated in tumors and penetrated beyond tumor blood vessels; CAR expression was substantially higher under hypoxic conditions.
• Treatment increased tumor infiltration by CD8+ T cells and NK cells. CD8+ T-cell infiltration was 3.33 times that in untreated controls, with increased granzyme B and interferon-gamma expression.
• In the 4T1 model, mean tumor weight was approximately 9.2% of the control value; complete regression occurred in two of six treated mice.
• Median survival increased from 22.5 to 42.5 days in the 4T1 model and from 22.5 to 44.5 days in the EMT6 model.
• Safety experiments suggested that hypoxia-responsive regulation reduced off-target CAR expression and associated inflammatory effects compared with a formulation without that regulation.

Interpretation:

The study reports preclinical evidence that tumor-targeted lipoplexes can generate CAR-expressing immune cells locally and improve antitumor activity in mouse breast cancer models.

Limitations:

• The findings are preclinical and were reported in mouse models; the context provides no human study results.

Conclusion:

The researchers propose local engineering of immune cells as an alternative to conventional CAR T-cell manufacturing and delivery approaches.

Sources:

• Article context provided by the user