Microwave ablation combined with anti-PD-1 therapy enhances systemic antitumor immunity in a multitumor murine model of Hepa1-6

Microwave ablation combined with PD-L1 blockade synergistically promotes Cxcl9-mediated antitumor immunity

Although microwave ablation (MWA) is an important curative therapy in colorectal cancer liver metastasis, recurrence still occurs clinically. Our previous studies have shown that the expression of programmed cell death 1 ligand 1 (PD-L1) is upregulated following MWA, suggesting that MWA combined with anti-PD-L1 treatment can serve as a promising clinical therapeutic strategy against cancer. Using MWA-treated preclinical mice models, MWA combined with αPD-L1 treatment decreased tumor growth and prolonged overall survival (OS). Furthermore, through flow cytometry and single-cell RNA sequencing analysis, we determined that the MWA plus αPD-L1 therapy significantly suppressed CD8+ T cell exhaustion and enhanced their effector function. A significant increase in γ-interferon (IFN-γ) stimulated transcription factors, specifically Irf8, was observed. This enhancement facilitated the polarization of tumor-associated macrophages (TAM1s and TAM2s) through the nuclear factor-κB/JAK-STAT1 signaling pathway. Furthermore, the combination therapy stimulated the production of CXC motif chemokine ligand (CXCL9) by TAM1s and tumor cells, potentially increasing the chemotaxis of CD8 T cells and Th1 cells. Knocking out Cxcl9 in MC38 tumor cells or using CXCL9 blockade enhanced tumor growth of untreated tumors and shortened OS. Taken together, our study showed that blocking the IFN-γ-Cxcl9-CD8+ T axis promoted tumor progression and discovered a potential involvement of IRF8-regulated TAMs in preventing T cell exhaustion. Collectively, we identified that the combination of MWA with anti-PD-L1 treatment holds promise as a therapeutic strategy to rejuvenate the immune response against tumors. This merits further exploration in clinical studies.

TGF-β1 inhibitor enhances the therapeutic effect of microwave ablation on hepatocellular carcinoma

BACKGROUND

Microwave ablation (MWA) is a widely adopted treatment technique for hepatocellular carcinoma (HCC). However, MWA alone is of limited use and has a high recurrence rate. Transforming growth factor-β1 (TGF-β1) is recognized as a potential therapeutic target for HCC patients. Therefore, this study was designed to investigate whether the TGF-β1 inhibitor could increase the efficacy of MWA therapy for HCC treatment.

METHODS

In vitro, HCC cells challenged with TGF-β1 inhibitor (SB-525334), or normal saline were then heated by microwave. Methyl tetrazolium assays were performed to detect cell survival rate and half-maximal drug inhibitory concentration (IC50). Cell viability and apoptosis were detected by cell counting kit-8 assays, flow cytometry and western blotting. In vivo, the mice injected with HepG2 cells received oral gavage of SB-525334 (20 mg/kg) or normal saline and MWA at a power of 15 W. Tumor volume was recorded. Expression of Ki67 and apoptosis-related proteins were detected by immunohistochemistry and western blotting. TUNEL assays were used to detect cell death ratio. Histopathological changes were examined by hematoxylin and eosin staining. The mechanisms associated with the function of MWA combined with TGF-β1 inhibitor in HCC development were explored by western blotting.

RESULTS

Combination of MWA and SB-525334 decreased the survival rate and promoted the apoptosis of HCC cells compared with MWA alone. SB-525334 enhanced the suppressive effect of MWA on tumor growth and amplified cell apoptosis. Mechanistically, MWA collaborated with SB-525334 inhibitor inactivated the TGF-β1/Smad2/Smad3 pathway.

CONCLUSION

TGF-β1 inhibitor enhances the therapeutic effect of MWA on HCC.

A study on combination of non-ablative local RFA with PD-1 and angiogenesis blocking to prolong survival through improvement of immune microenvironment in advanced Hepatocellular Carcinoma

Radiofrequency ablation (RFA), an effective local treatment method for early-stage Hepatocellular Carcinoma (HCC), combined with PD-1 blocking and anti-angiogenic therapy is being extensively explored in advanced HCC, however, the definite results and underlying mechanisms still remain to be elucidated. Therefore, whether non-ablative RFA-based combined therapy can play a synergistic anti-tumor effect through improving tumor immune microenvironment was investigated by us in HCC mouse models. Our results showed that non-ablative RFA could regulate multilayered immunity, such as inducing immunogenic death of tumor cells, upregulating the secretion of inflammatory cytokines, mainly IFN-γ, TNF-α, and IL-10, and subsequently promoting the infiltration of CD8 + T cells. As a result, a significant synergistic anti-tumor effect was demonstrated in the combination therapy group. Similarly, in the real-world setting, non-curative RFA combined with PD-1 blocking and Lenvatinib for 12 patients with Barcelona Clinic Liver Cancer (BCLC) stage C achieve promising results, with 6.9 months (95 % CI: 3.23-15.73) median progression-free survival (mPFS) and 12.7 months (95 % CI: 7.40-19.73) median overall survival (mOS). The common treatment-related adverse reactions were pneumonia and thyroiditis with low prevalence, both less than grade 3 and manageable by symptomatic treatment. Summarily, local non-ablative RFA should be a clinically preferred strategy in combination with PD-1 blocking and anti-angiogenic therapy, because this more flexible scheme abandons its historical concept of tumor eradication, but fully utilizes the immune regulatory function by inducing immunogenic tumor death and has higher-level of safety. Therefore, this is a two-pronged and highly balanced approach to achieved favorable treatment outcomes, while conclusive evidence is still pending, it can be attempted in the real world anyway.

Efficacy and safety of microwave ablation and its synergistic potential in the treatment of early-stage non-small cell lung cancer

Lung cancer remains the primary cause of cancer-related mortality globally. In the case of early-stage non-small cell lung cancer (NSCLC), surgical resection, such as lobectomy and sub-lobectomy, continues to be the established standard treatment. However, for patients with insufficient cardiopulmonary function and multiple comorbidities who are unable to undergo surgical resection, nonoperative local therapies, including radiotherapy and thermal ablation, are preferred. In recent years, microwave ablation (MWA) has gained popularity for treating early-stage NSCLC due to its high heating efficiency, good tissue conductance, and heat conduction capabilities. This review provides a comprehensive summary of the current efficacy and safety data regarding MWA for early-stage NSCLC and discusses the potential benefits of combining MWA with other therapies.

Synergizing Thermal Ablation Modalities with Immunotherapy: Enough to Induce Systemic Antitumoral Immunity?

Thermal ablation modalities (cryoablation, radiofrequency ablation, and microwave ablation) have long been noted to occasionally induce a systemic antitumoral response. With the widespread use of checkpoint inhibitors, there is a significant interest in whether thermal ablation can promote immune system tumor recognition and increase checkpoint inhibitor response rates. In this review, we examine the current state of preclinical and clinical evidence examining the combination of checkpoint inhibitor therapies and thermal ablation modalities as well as discuss remaining the unanswered questions and directions for future research.

Synergistic Effects of Nanoscale CaO2 Combined with PD-1 Inhibitors in the Treatment of Hepatocellular Carcinoma: A Promising Combination

Purpose

To explore the effect of calcium peroxide nanoparticles (CaO2 NPs) combined with programmed cell death protein 1 (PD-1) inhibitors in the treatment of liver cancer and its related mechanism.

Methods

Hepa1-6 cells were cultured to construct the Hepa1-6 mouse liver cancer model. In vivo mechanism study, a unilateral tumor model was established. Eighteen tumor-bearing mice were randomly divided into the control group (intra-tumoral injection of PBS solution) and the experimental group (intra-tumoral injection of CaO2 NPs). A hypoxic probe, pH probe, and micro-CT were used to evaluate the effect of CaO2 NPs on improving hypoxia, neutralizing acidity, and inducing calcium overload within the tumor. To study the effect of CaO2 NPs combined with PD-1 inhibitors on proximal and distal tumors, the bilateral tumor model was established. Forty tumor-bearing mice were randomly divided into the control group (intra-tumoral/intra-peritoneal injection of PBS solution), CaO2 NPs group (intra-tumoral injection of CaO2 NPs), PD-1 group (intra-peritoneal injection of PD-1 inhibitor), and the combination group (intra-tumoral injection of CaO2 NPs and intra-peritoneal injection of PD-1 inhibitors). The administered side was recorded as the proximal tumor. Tumor volume and body weight were measured every 2 days after treatment. On day 8, serum and tumor samples were collected. The immune factors in serum (Interferon-γ (IFN-γ), Tumour necrosis factor-α (TNF-α), Interleukin-2 (IL-2), and Interleukin-10 (IL-10)) and tumor tissue (IFN-γ and TNF-α) were detected by ELISA. H&E staining was used to detect tumor necrosis. Immunohistochemical staining was used to detect the amount of CD4+ and CD8+ T cells within the tumor. By analyzing the tumor volume, pathological indexes, and immune-related indexes, the effects of CaO2 NPs combined with PD-1 inhibitors on proximal and distal tumors were evaluated, and they mediated immunomodulatory effects (including local and systemic immunity), and their effects on tumor burden were studied. In addition, a unilateral tumor model was established to study the effect of CaO2 NPs combined with PD-1 inhibitors on survival time.

Results

The results of in vivo mechanism study showed that CaO2 NPs can improve hypoxia, neutralize acidity, and induce calcium overload within tumors. The results of the study on the effect of CaO2 NPs combined with PD-1 inhibitor on proximal and distal tumors showed that, compared with the other three groups, the bilateral tumor burden of the combination group was significantly reduced, the intra-tumoral infiltration of CD8+ and CD4+ T cells were significantly increased, the secretion of anti-tumor immune factors in tumor and serum was increased, and the secretion of pro-tumor immune factors was decreased. Mice in the combination group showed the longest survival compared with the other groups.

Conclusion

CaO2 NPs can improve hypoxia, neutralize acidity, and induce calcium overload within tumors, so as to reduce tumor burden and realize an immunosuppressive tumor transformation to a hot tumor, and play a synergistic role with PD-1 inhibitors in anti-liver cancer.

More Ultrasound-Guided Percutaneous Microwave Ablation Leads to Higher Immune-Related Gene Expression and Boosts PD-1 Monoclonal Antibodies for Liver Cancer

OBJECTIVE

The aim of the work described here was to investigate the relative contribution of subtotal ultrasound-guided percutaneous microwave ablation (MWA) to amplifying programmed cell death protein-1 (PD-1) inhibition in advanced hepatocellular carcinoma (HCC).

METHODS

Between April 2019 and December 2021, advanced HCC patient demographics, tumor response, survival data, neutrophil-to-lymphocyte ratio (NLR) and peripheral lymphocyte profiles were retrospectively collected and analyzed. In hepa1-6 tumor-bearing C57BL/6J mice, RNA sequencing, flow cytometry, immunohistochemistry staining and cytokine tests were also performed.

RESULTS

Twenty-nine HCC patients were enrolled, with a median follow-up duration of 15.1 mo. Compared with the ablation rate (AR) ≤50% group (n = 10), the AR >50% group (n = 19) had a higher disease control rate, a longer time to progression and a longer overall survival. More patients in the AR >50% group had an early decrease in NLR and better immune activation. RNA sequencing of murine tumors subjected to MWA >50% AR showed that immune-related gene expression upregulated. CD8+ T cells, interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) were also increased, indicating that MWA >50% AR boosted the immunomodulatory effect of PD-1 inhibitors.

CONCLUSION

More MWA could induce superior antitumor immunity by enhancing immune-related gene expression, priming CD8+ T cells and thereby boosting PD-1 inhibition. It is advisable that eradication of tumors to the degree possible should be considered within technical access to obtain a better prognosis.

PD-1 monoclonal antibodies enhance the cryoablation-induced antitumor immune response: a breast cancer murine model research

BACKGROUND

It has been demonstrated that cryoablation (Cryo) causes specific T-cell immune responses in the body; however, it is not sufficient to prevent tumor recurrence and metastasis. In this report, we evaluated changes in the tumor immune microenvironment (TIME) in distant tumor tissues after Cryo and investigated the immunosuppressive mechanisms that limit the efficacy of Cryo.

METHODS

Bilateral mammary tumor models were established in mice, and we first observed the dynamic changes in immune cells and cytokines at different time points after Cryo. Then, we confirmed that the upregulation of PD-1 and PD-L1 signaling in the contralateral tumor tissue was closely related to the immunosuppressive state in the TIME at the later stage after Cryo. Finally, we also evaluated the synergistic antitumor effects of Cryo combined with PD-1 monoclonal antibody (mAb) in the treatment of breast cancer (BC) mouse.

RESULTS

We found that Cryo can stimulate the body's immune response, but it also induces immunosuppression. The elevated PD-1/PD-L1 expression in distant tumor tissues at the later stage after Cryo was closely related to the immunosuppressive state in the TIME but also created the conditions for Cryo combined with PD-1 mAb for BC mouse treatment. Cryo + PD-1 mAb could improve the immunosuppressive state of tumors and enhance the Cryo-induced immune response, thus exerting a synergistic antitumor effect.

CONCLUSIONS

The PD-1/PD-L1 axis plays an important role in suppressing Cryo-induced antitumor immune responses. This study provides a theoretical basis for Cryo combined with PD-1 mAb therapy in clinical BC patients.

Inducing the Abscopal Effect in Liver Cancer Treatment: The Impact of Microwave Ablation Power Levels and PD-1 Antibody Therapy

Microwave ablation (MWA) is an effective treatment for liver cancer (LC), but its impact on distant tumors remains to be fully elucidated. This study investigated the abscopal effects triggered by MWA treatment of LC, at different power levels and with or without combined immune checkpoint inhibition (ICI). We established a mouse model with bilateral subcutaneous LC and applied MWA of varied power levels to ablate the right-sided tumor, with or without immunotherapy. Left-sided tumor growth was monitored to assess the abscopal effect. Immune cell infiltration and distant tumor neovascularization were quantified via immunohistochemistry, revealing insights into the tumor microenvironment and neovascularization status. Th1- and Th2-type cytokine concentrations in peripheral blood were measured using ELISA to evaluate systemic immunological changes. It was found that MWA alone, especially at lower power, promoted distant tumor growth. On the contrary, combining high-power MWA with anti-programmed death (PD)-1 therapy promoted CD8+ T-cell infiltration, reduced regulatory T-cell infiltration, upregulated a Th1-type cytokine (TNF-α) in peripheral blood, and inhibited distant tumor growth. In summary, combining high-power MWA with ICI significantly enhances systemic antitumor immune responses and activates the abscopal effect, offering a facile and robust strategy for improving treatment outcomes.

A Phase 1/2 Multicenter Randomized Trial of Local Ablation plus Toripalimab versus Toripalimab Alone for Previously Treated Unresectable Hepatocellular Carcinoma

PURPOSE

To assess the safety and efficacy of local ablation plus PD-1 inhibitor toripalimab in previously treated unresectable hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

In the multicenter, two-stage, and randomized phase 1/2 trial, patients were randomly assigned to receive toripalimab alone (240 mg, every 3 weeks), subtotal local ablation followed by toripalimab starting on post-ablation day 3 (Schedule D3), or on post-ablation day 14 (Schedule D14). The first endpoint of stage 1 was to determine which combination schedule could continue and progression-free survival (PFS) as the primary endpoint for stage 1/2.

RESULTS

A total of 146 patients were recruited. During stage 1, Schedule D3 achieved numerically higher objective response rate (ORR) than Schedule D14 for non-ablation lesions (37.5% vs. 31.3%), and was chosen for stage 2 evaluation. For the entire cohort of both stages, patients with Schedule D3 had a significantly higher ORR than with toripalimab alone (33.8% vs. 16.9%; P = 0.027). Moreover, patients with Schedule D3 had improved median PFS (7.1 vs. 3.8 months; P < 0.001) and median overall survival (18.4 vs. 13.2 months; P = 0.005), as compared with toripalimab alone. In addition, six (9%) patients with toripalimab, eight (12%) with Schedule D3, and 4 (25%) with Schedule D14 developed grade 3 or 4 adverse events, and one patient (2%) with Schedule D3 manifested grade 5 treatment-related pneumonitis.

CONCLUSIONS

In patients with previously treated unresectable HCC, subtotal ablation plus toripalimab improved the clinical efficacy as compared with toripalimab alone, with an acceptable safety profile.

Potential Immunotherapy Targets for Liver-Directed Therapies, and the Current Scope of Immunotherapeutics for Liver-Related Malignancies

Liver cancer, including hepatocellular carcinoma and intrahepatic cholangiocarcinoma, is increasing in incidence and mortality across the globe. An improved understanding of the complex tumor microenvironment has opened many therapeutic doors and led to the development of novel pharmaceuticals targeting cellular signaling pathways or immune checkpoints. These interventions have significantly improved tumor control rates and patient outcomes, both in clinical trials and in real-world practice. Interventional radiologists play an important role in the multidisciplinary team given their expertise in minimally invasive locoregional therapy, as the bulk of these tumors are usually in the liver. The aim of this review is to highlight the immunological therapeutic targets for primary liver cancers, the available immune-based approaches, and the contributions that interventional radiology can provide in the care of these patients.

Combining energy-based focal ablation and immune checkpoint inhibitors: preclinical research and clinical trials

Energy-based focal therapy (FT) uses targeted, minimally invasive procedures to destroy tumors while preserving normal tissue and function. There is strong emerging interest in understanding how systemic immunity against the tumor can occur with cancer immunotherapy, most notably immune checkpoint inhibitors (ICI). The motivation for combining FT and ICI in cancer management relies on the synergy between the two different therapies: FT complements ICI by reducing tumor burden, increasing objective response rate, and reducing side effects of ICI; ICI supplements FT by reducing local recurrence, controlling distal metastases, and providing long-term protection. This combinatorial strategy has shown promising results in preclinical study (since 2004) and the clinical trials (since 2011). Understanding the synergy calls for understanding the physics and biology behind the two different therapies with distinctive mechanisms of action. In this review, we introduce different types of energy-based FT by covering the biophysics of tissue-energy interaction and present the immunomodulatory properties of FT. We discuss the basis of cancer immunotherapy with the emphasis on ICI. We examine the approaches researchers have been using and the results from both preclinical models and clinical trials from our exhaustive literature research. Finally, the challenges of the combinatory strategy and opportunities of future research is discussed extensively.

Microwave ablation and synchronous transarterial chemoembolization combined with PD-1 inhibitor in patients with hepatocellular carcinoma following tyrosine kinase inhibitor intolerance

Purpose

To determine the safety and efficacy of microwave ablation (MWA) and synchronous transarterial chemoembolization (TACE) combined with or without PD-1 inhibitor in patients with hepatocellular carcinoma (HCC) following tyrosine kinase inhibitor (TKI) intolerance.

Materials and methods

This study retrospectively enrolled TKI-intolerant HCC patients who underwent MWA-TACE combined with PD-1 inhibitor (MTP) or MWA-TACE (MT) from January 2019 to June 2021. MWA and TACE were performed simultaneously, and PD-1 inhibitor was administered intravenously at a dose of 200 mg once every three weeks after MWA-TACE. Adverse events (AEs) related to treatment were recorded during the follow-up. Progression-free survival (PFS) and overall survival (OS) were compared between the two groups.

Results

A total of 87 patients were included and classified into the MTP group (n =42) and MT group (n=45). Complications related to MWA-TACE in the MTP group were similar to that in the MT group (21.4% vs. 24.4%, P = 0.738). Moreover, 35 (83.3%) patients had eighty-four AEs related to PD-1 inhibitor in the MTP group, and 8 (19.0%) patients developed grade 3. Patients who underwent MWA-TACE combined with PD-1 inhibitor had better PFS (median, 10.0 vs. 4.7 months, P < 0.001) and OS (median, 17.0 vs. 8.5 months, P < 0.001) than those who underwent MWA-TACE alone. Treatment method and Child-Pugh class were independent prognostic factors for survival in the univariate and multivariate analysis.

Conclusion

MWA and synchronous TACE combined with PD-1 inhibitor might be a favorable treatment option in TKI-intolerant HCC patients.

Microwave ablation induces abscopal effect via enhanced systemic antitumor immunity in colorectal cancer

Background

Thermal ablation is the primary procedure for the local treatment of lung metastases. It is known that radiotherapy and cryoablation can stimulate an abscopal effect, while the occurrence of abscopal effect induced by microwave ablation is less; the cellular and molecular mechanisms involved in the abscopal effect after microwave ablation should be further elucidated.

Methods

CT26 tumor-bearing Balb/c mice were treated with microwave ablation with several combinations of ablation power and time duration. The growth of primary or abscopal tumors and the survival of mice were both monitored; moreover, immune profiles in abscopal tumors, spleens, and lymph nodes were examined by flow cytometry.

Results

Microwave ablation suppressed tumor growth in both primary and abscopal tumors. Both local and systemic T-cell responses were induced by microwave ablation. Furthermore, the mice exhibiting significant abscopal effect after microwave ablation markedly elevated Th1 cell proportion both in the abscopal tumors and spleens.

Conclusions

Microwave ablation at 3 w-3 min not only suppressed tumor growth in the primary tumors but also stimulated an abscopal effect in the CT26-bearing mice via the improvement of systemic and intratumoral antitumor immunity.

Thermal ablation versus radiotherapy for inoperable stage III non-small cell lung cancer: a propensity score matching analysis

OBJECTIVE

To compare the survival benefits of thermal ablation (TA) and radiotherapy in inoperable patients with stage III non-small cell lung cancer (NSCLC).

METHOD

A retrospective analysis was conducted using the data from the Surveillance, Epidemiology, and End Results (SEER) program. Propensity score matching (PSM) was conducted to balance potential baseline confounding factors. Survival analyses were conducted using Kaplan-Meier and Cox regression methods.

RESULTS

The present study included 33,393 inoperable patients with stage III NSCLC, including 106 patients treated with TA and 33,287 patients treated with radiotherapy. No statistical difference in overall survival (OS) (p = .065) or cancer-specific survival (CSS) (p = .996) was found between the patients treated with TA and those treated with radiotherapy. Using 1:3 matching, a matched cohort of 420 patients (105 patients treated with TA, 315 patients treated with radiotherapy) was identified. The differences in OS (p = .177) and CSS (p = .605) were still not significant between the radiotherapy and TA groups after PSM. According to subgroup analyses, TA showed comparable survival benefits in almost all subgroups compared to radiotherapy.

CONCLUSION

For inoperable stage III NSCLC, the survival benefit of TA was comparable to radiotherapy. TA may be a potential therapeutic modality for inoperable stage III NSCLC.

Nanoscale CaO2 materials for synergistic transarterial chemoembolization in a VX2 orthotopic rabbit liver cancer model

Transcatheter arterial chemoembolization (TACE) is extensively used in the treatment of hepatocellular carcinoma (HCC), but its efficacy is usually limited to secondary tumor hypoxia and other progressive exacerbation of the abnormal tumor microenvironment (TME). Herein, we synthesized polyvinyl pyrrolidone (PVP)-coated CaO₂ nanoparticles (CaO₂ NPs) and applied them as a synergistic agent to improve the antitumor efficacy of TACE. After injection into the tumor, CaO₂ NPs reacted with water to generate abundant oxygen, hydroxyl ions (OH^-), and calcium ions (Ca²⁺), thereby relieving tumor hypoxia, neutralizing acid, and overloading Ca²⁺ to mediate antitumor effects. Moreover, the effect of chemotherapeutic drugs within the TACE was improved due to the modulated TME. CaO₂ NPs efficiently regulated the TME and improved the antitumor effect of doxorubicin under hypoxia conditions in vitro. Compared to other groups, the TACE+CaO₂ NPs group achieved the lowest tumor growth rate, highest tumor necrosis rate, lowest expression of histological markers associated with hypoxia and angiogenesis (HIF-α, VEGF, and CD31), and highest CD8⁺ T cell recruitment in vivo. Thus, these findings demonstrated that CaO₂ NPs provide synergy for TACE therapy in the VX2 orthotopic rabbit liver cancer model, suggesting that they have a potential broad clinical application. STATEMENT OF SIGNIFICANCE: The efficacy of transcatheter arterial chemoembolization (TACE) for treatment of hepatocellular carcinoma is usually limited to secondary tumor hypoxia and other progressive exacerbation of the abnormal tumor microenvironment (TME). To address this issue, we synthesized CaO₂ nanoparticles (CaO₂ NP_S) which would react with water to generate abundant oxygen, hydroxyl ions (OH^-), and calcium ions (Ca²⁺), thereby relieving tumor hypoxia, neutralizing the acidic TME, and inducing Ca²⁺ overloading. The efficacy of CaO₂ NPs in combination with TACE was investigated in an orthotopic rabbit liver cancer model, and the results showed the great synergetic antitumor effect of TACE and CaO₂ NPs.

Combinatory local ablation and immunotherapies for hepatocellular carcinoma: Rationale, efficacy, and perspective

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related death worldwide. Local ablation, such as radiofrequency ablation, microwave ablation, cryoablation and irreversible electroporation, etc., are well established in elimination and control of HCC. However, high recurrence rate after local ablation remains the biggest challenge for HCC management. Novel and effective therapeutic strategies to improve long-term survival are urgently needed. Accumulating studies have reported the role of ablation in modulating the tumor signaling pathway and the immune microenvironment to both eliminate residual/metastatic tumor and promote tumor progression. Ablation has been shown to elicit tumor-specific immune responses by inducing massive cell death and releasing tumor antigen. Immunotherapies that unleash the immune system have the potential to enhance the anti-tumor immunity induced by ablation. Multiple combinatory strategies have been explored in preclinical and clinical studies. In this review, we comprehensively summarize the latest progress on different mechanisms underlying the effects of ablation on tumor cells and tumor microenvironment. We further analyze the clinical trials testing the combination of ablation and immunotherapies, and discuss the possible role of immunomodulation to boost the anti-tumor effects of ablation and prevent HCC recurrence.

Rational Nanomedicine Design Enhances Clinically Physical Treatment-Inspired or Combined Immunotherapy

Independent of tumor type and non-invasive or minimally-invasive feature, current physical treatments including ultrasound therapy, microwave ablation (MWA), and radiofrequency ablation (RFA) are widely used as the local treatment methods in clinics for directly killing tumors and activating systematic immune responses. However, the activated immune responses are inadequate and incompetent for tumor recession, and the incomplete thermal ablation even aggravates the immunosuppressive tumor microenvironment (ITM), resulting in the intractable tumor recurrence and metastasis. Intriguingly, nanomedicine provides a powerful platform as they can elevate energy utilization efficiency and augment oncolytic effects for mitigating ITM and potentiating the systematic immune responses. Especially after combining with clinical immunotherapy, the anti-tumor killing effect by activating or enhancing the human anti-tumor immune system is reached, enabling the effective prevention against tumor recurrence and metastasis. This review systematically introduces the cutting-edge progress and direction of nanobiotechnologies and their corresponding nanomaterials. Moreover, the enhanced physical treatment efficiency against tumor progression, relapse, and metastasis via activating or potentiating the autologous immunity or combining with exogenous immunotherapeutic agents is exemplified, and their rationales are analyzed. This review offers general guidance or directions to enhance clinical physical treatment from the perspectives of immunity activation or magnification.

Combination treatment of radiofrequency ablation and peptide neoantigen vaccination: Promising modality for future cancer immunotherapy

Background

The safety and immunogenicity of a personalized neoantigen-based peptide vaccine, iNeo-Vac-P01, was reported previously in patients with a variety of cancer types. The current study investigated the synergistic effects of radiofrequency ablation (RFA) and neoantigen vaccination in cancer patients and tumor-bearing mice.

Methods

Twenty-eight cancer patients were enrolled in this study, including 10 patients who had received RFA treatment within 6 months before vaccination (Cohort 1), and 18 patients who had not (Cohort 2). Individualized neoantigen peptide vaccines were designed, manufactured, and subcutaneously administrated with GM-CSF as an adjuvant for all patients. Mouse models were employed to validate the synergistic efficacy of combination treatment of RFA and neoantigen vaccination.

Results

Longer median progression free survival (mPFS) and median overall survival (mOS) were observed in patients in Cohort 1 compared to patients in Cohort 2 (4.42 and 20.18 months vs. 2.82 and 10.94 months). The results of ex vivo IFN-γ ELISpot assay showed that patients in Cohort 1 had stronger neoantigen-specific immune responses at baseline and post vaccination. Mice receiving combination treatment of RFA and neoantigen vaccines displayed higher antitumor immune responses than mice receiving single modality. The combination of PD-1 blockage with RFA and neoantigen vaccines further enhanced the antitumor response in mice.

Conclusion

Neoantigen vaccination after local RFA treatment could improve the clinical and immune response among patients of different cancer types. The synergistic antitumor potentials of these two modalities were also validated in mice, and might be further enhanced by immune checkpoint inhibition. The mechanisms of their synergies require further investigation.

Clinical trial registration

https://clinicaltrials.gov/, identifier NCT03662815.

Hepatocellular Carcinoma Intrinsic Cell Death Regulates Immune Response and Prognosis

Ablative and locoregional treatment options, such as radiofrequency, ethanol injection, microwave, and cryoablation, as well as irreversible electroporation, are effective therapies for early-stage hepatocellular carcinoma (HCC). Hepatocyte death caused by ablative procedures is known to increase the release of tumor-associated antigen, thus enhancing tumor immunogenicity. In addition, the heat ablative resection induces pyroptotic cell death accompanied by the release of several inflammatory factors and immune-related proteins, including damage-associated molecular patterns (DAMPs), heat shock proteins (HSPs), ficolin 3, ATP, and DNA/RNA, which potentiate the antitumoral immune response. Surgical approaches that enhance tumor necrosis and reduce hypoxia in the residual liver parenchyma have been shown to increase the disease-free survival rate by reducing the host’s immunosuppressive response. Scalpel devices and targeted surgical approach combined with immune-modulating drugs are an interesting and promising area to maximize therapeutic outcomes after HCC ablation.