Bisphosphonate-mineralized nano-IFNγ suppresses residual tumor growth caused by incomplete radiofrequency ablation through metabolically remodeling tumor-associated macrophages.

Abstract

Rationale: Radiofrequency ablation (RFA), as a minimally invasive surgery strategy based on local thermal-killing effect, is widely used in the clinical treatment of multiple solid tumors. Nevertheless, RFA cannot achieve the complete elimination of tumor lesions with larger burden or proximity to blood vessels. Incomplete RFA (iRFA) has even been validated to promote residual tumor growth due to the suppressive tumor immune microenvironment (TIME). Therefore, exploring strategies to remodel TIME is a key issue for the development of RFA therapy. Methods: The negative effect of iRFA on colorectal cancer therapy was firstly investigated. Then a zoledronate-mineralized nanoparticle loaded with IFNγ (Nano-IFNγ/Zole) was designed and its tumor suppressive efficacy was evaluated. Finally, the metabolic reprogramming mechanism of Nano-IFNγ/Zole on tumor-associated macrophages (TAMs) was studied in detail. Results: We found iRFA dynamically altered TIME and promoted TAM differentiation from M1 to M2. Nano-IFNγ/Zole was fabricated to metabolically remodel TAMs. IFNγ in Nano-IFNγ/Zole concentrated in the ablation site to play a long-term remodeling role. Acting on mevalonate pathway, Nano-IFNγ/Zole was discovered to reduce lysosomal acidification and activate transcription factor TFEB by inhibiting isoprene modification of the Rab protein family. These mechanisms, in conjunction with IFNγ-activated JAK/STAT1 signaling, accelerated the reprogramming of TAMs from M2 to M1, and suppressed tumor recurrence after iRFA. Conclusions: This study elaborates the synergistic mechanism of zoledronate and IFNγ in Nano-IFNγ/Zole to reshape suppressive TIME caused by iRFA by remodeling TAMs, and highlights the important value of metabolically induced cellular reprogramming. Since both zoledronate and IFNγ have already been approved in clinics, this integrative nano-drug delivery system establishes an effective strategy with great translational promise to overcome the poor prognosis after clinically incomplete RFA.