Short-course neoadjuvant in situ vaccination for murine melanoma

Neoadjuvant intratumoral MBT(A) immunotherapy prevents distant metastases and recurrence in murine models

Neoadjuvant immunotherapy represents a pioneering approach in the preoperative treatment of cancer, providing new strategies for tumor reduction and improved patient outcomes by modulating the immune response. This study investigated neoadjuvant immunotherapy using intratumoral administration of mannan-BAM, Toll-like receptor ligands, and anti-CD40 antibody (MBTA therapy) followed by surgery in murine models of MTT pheochromocytoma, B16-F10 melanoma, and 4T1 and E0771.lmb mammary carcinomas. In the MTT pheochromocytoma model, it was found that neoadjuvant MBTA therapy followed by surgery could prevent the development of distant metastases in 100% of treated animals, compared to a 60% mortality rate in the control group due to metastatic disease after surgery. These outcomes were achieved even in tumors three times larger than those in the control group. In the aggressive 4T1 model, neoadjuvant MBTA therapy resulted in slower tumor progression and a significant prolongation of survival. In the B16-F10 and E0771.lmb models, neoadjuvant MBTA therapy also protected animals from metastases development and tumor recurrence upon rechallenge with tumor cells after surgery. Transcriptomic analysis revealed enhanced effector immune cell infiltration, cytotoxicity, and antigen presentation in retransplanted tumors from MBTA-treated mice, indicating robust immune memory. Notably, the exclusion of the anti-CD40 antibody from the neoadjuvant MBTA therapy (MBT therapy) yielded comparable outcomes in protection against metastases development. These findings advocate for further investigation of intratumoral neoadjuvant MBTA therapy for immunologically "cold" tumors, including those at high risk of metastases or recurrence.

Advances in therapeutic cancer vaccines: Harnessing immune adjuvants for enhanced efficacy and future perspectives

Preventive cancer vaccines are highly effective in preventing viral infection-induced cancer, but advances in therapeutic cancer vaccines with a focus on eliminating cancer cells through immunotherapy are limited. To develop therapeutic cancer vaccines, the integration of optimal adjuvants is a potential strategy to enhance or complement existing therapeutic approaches. However, conventional adjuvants do not satisfy the criteria of clinical trials for therapeutic cancer vaccines. To improve the effects of adjuvants in therapeutic cancer vaccines, effective vaccination strategies must be formulated and novel adjuvants must be identified. This review offers an overview of the current advancements in therapeutic cancer vaccines and highlights in situ vaccination approaches that can be synergistically combined with other immunotherapies by harnessing the adjuvant effects. Additionally, the refinement of adjuvant systems using cutting-edge technologies and the elucidation of molecular mechanisms underlying immunogenic cell death to facilitate the development of innovative adjuvants have been discussed.

Emerging Indications for Neoadjuvant Systemic Therapies in Cutaneous Malignancies

Patients with cutaneous malignancies and locoregional involvement represent a high-risk population for disease recurrence, even if they receive optimal surgery and adjuvant treatment. Here, we discuss how neoadjuvant therapy has the potential to offer significant advantages over adjuvant treatment, further improving outcomes in some patients with skin cancers, including melanoma, Merkel cell carcinoma, and cutaneous squamous-cell carcinoma. Both preclinical studies and in vivo trials have demonstrated that exposure to immunotherapy prior to surgical resection can trigger a broader and more robust immune response, resulting in increased tumor cell antigen presentation and improved targeting by immune cells, potentially resulting in superior outcomes. In addition, neoadjuvant approaches hold the possibility of providing a platform for evaluating pathological responses in the resected lesion, optimizing the prognosis and enabling personalized adaptive management, in addition to expedited drug development. However, more data are still needed to determine the ideal patient selection and the best treatment framework and to identify reliable biomarkers of treatment responses. Although there are ongoing questions regarding neoadjuvant treatment, current data support a paradigm shift toward considering neoadjuvant therapy as the standard approach for selecting patients with high-risk skin tumors.

Quantifying in vivo collagen reorganization during immunotherapy in murine melanoma with second harmonic generation imaging

Significance

Increased collagen linearization and deposition during tumorigenesis can impede immune cell infiltration and lead to tumor metastasis. Although melanoma is well studied in immunotherapy research, studies that quantify collagen changes during melanoma progression and treatment are lacking.

Aim

We aim to image in vivo collagen in preclinical melanoma models during immunotherapy and quantify the collagen phenotype in treated and control mice.

Approach

Second-harmonic generation imaging of collagen was performed in mouse melanoma tumors in vivo over a treatment time course. Animals were treated with a curative radiation and immunotherapy combination. Collagen morphology was quantified over time at an image and single-fiber level using CurveAlign and CT-FIRE software.

Results

In immunotherapy-treated mice, collagen was reorganized toward a healthy phenotype, including shorter, wider, curlier collagen fibers, with modestly higher collagen density. Temporally, collagen fiber straightness and length changed late in treatment (days 9 and 12), while width and density changed early (day 6) compared with control mice. Single-fiber collagen features calculated in CT-FIRE were the most sensitive to the changes among treatment groups compared with bulk collagen features.

Conclusions

Quantitative second-harmonic generation imaging can provide insight into collagen dynamics in vivo during immunotherapy, with key implications in improving immunotherapy response in melanoma and other cancers.

Quantifying in vivo collagen reorganization during immunotherapy in murine melanoma with second harmonic generation imaging

Significance

Increased collagen linearization and deposition during tumorigenesis can impede immune cell infiltration and lead to tumor metastasis. Although melanoma is well studied in immunotherapy research, studies that quantify collagen changes during melanoma progression and treatment are lacking.

Aim

Image in vivo collagen in preclinical melanoma models during immunotherapy and quantify the collagen phenotype in treated and control mice.

Approach

Second harmonic generation imaging of collagen was performed in mouse melanoma tumors in vivo over a treatment time-course. Animals were treated with a curative radiation and immunotherapy combination. Collagen morphology was quantified over time at an image and single fiber level using CurveAlign and CT-FIRE software.

Results

In immunotherapy-treated mice, collagen reorganized toward a healthy phenotype, including shorter, wider, curlier collagen fibers, with modestly higher collagen density. Temporally, collagen fiber straightness and length changed late in treatment (Day 9 and 12) while width and density changed early (Day 6) compared to control mice. Single fiber level collagen analysis was most sensitive to the changes between treatment groups compared to image level analysis.

Conclusions

Quantitative second harmonic generation imaging can provide insight into collagen dynamics in vivo during immunotherapy, with key implications in improving immunotherapy response in melanoma and other cancers.

Effectiveness of radiotherapy and targeted radionuclide therapy for melanoma in preclinical mouse models: A combination treatments overview

Cutaneous melanoma is an aggressive and highly metastatic skin cancer. In recent years, immunotherapy and targeted small-molecule inhibitors have improved the overall survival of patients. Unfortunately, most patients in advanced stages of disease exhibit either intrinsically resistant or rapidly acquire resistance to these approved treatments. However, combination treatments have emerged to overcome resistance, and novel treatments based on radiotherapy (RT) and targeted radionuclide therapy (TRT) have been developed to treat melanoma in the preclinical mouse model, raising the question of whether synergy in combination therapies may motivate and increase their use as primary treatments for melanoma. To help clarify this question, we reviewed the studies in preclinical mouse models where they evaluated RT and TRT in combination with other approved and unapproved therapies from 2016 onwards, focusing on the type of melanoma model used (primary tumor and or metastatic model). PubMed® was the database in which the search was performed using mesh search algorithms resulting in 41 studies that comply with the inclusion rules of screening. Studies reviewed showed that synergy with RT or TRT had strong antitumor effects, such as tumor growth inhibition and fewer metastases, also exhibiting systemic protection. In addition, most studies were carried out on antitumor response for the implanted primary tumor, demonstrating that more studies are needed to evaluate these combined treatments in metastatic models on long-term protocols.

Single cell metabolic imaging of tumor and immune cells in vivo in melanoma bearing mice

Introduction

Metabolic reprogramming of cancer and immune cells occurs during tumorigenesis and has a significant impact on cancer progression. Unfortunately, current techniques to measure tumor and immune cell metabolism require sample destruction and/or cell isolations that remove the spatial context. Two-photon fluorescence lifetime imaging microscopy (FLIM) of the autofluorescent metabolic coenzymes nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and flavin adenine dinucleotide (FAD) provides in vivo images of cell metabolism at a single cell level.

Methods

Here, we report an immunocompetent mCherry reporter mouse model for immune cells that express CD4 either during differentiation or CD4 and/or CD8 in their mature state and perform in vivo imaging of immune and cancer cells within a syngeneic B78 melanoma model. We also report an algorithm for single cell segmentation of mCherry-expressing immune cells within in vivo images.

Results

We found that immune cells within B78 tumors exhibited decreased FAD mean lifetime and an increased proportion of bound FAD compared to immune cells within spleens. Tumor infiltrating immune cell size also increased compared to immune cells from spleens. These changes are consistent with a shift towards increased activation and proliferation in tumor infiltrating immune cells compared to immune cells from spleens. Tumor infiltrating immune cells exhibited increased FAD mean lifetime and increased protein-bound FAD lifetime compared to B78 tumor cells within the same tumor. Single cell metabolic heterogeneity was observed in both immune and tumor cells in vivo.

Discussion

This approach can be used to monitor single cell metabolic heterogeneity in tumor cells and immune cells to study promising treatments for cancer in the native in vivo context.

Intratumoral neoadjuvant immunotherapy based on the BO-112 viral RNA mimetic

BO-112 is a poly I:C-based viral mimetic that exerts anti-tumor efficacy when intratumorally delivered in mouse models. Intratumoral BO-112 synergizes in mice with systemic anti-PD-1 mAbs and this combination has attained efficacy in PD1-refractory melanoma patients. We sought to evaluate the anti-tumor efficacy of BO-112 pre-surgically applied in neoadjuvant settings to mouse models. We have observed that repeated intratumoral injections of BO-112 prior to surgical excision of the primary tumor significantly reduced tumor metastasis from orthotopically implanted 4T1-derived tumors and subcutaneous MC38-derived tumors in mice. Such effects were enhanced when combined with systemic anti-PD-1 mAb. The anti-tumor efficacy of this neoadjuvant immunotherapy approach depended on the presence of antigen-specific effector CD8 T cells and cDC1 antigen-presenting cells. Since BO-112 has been successful in phase-two clinical trials for metastatic melanoma, these results provide a strong rationale for translating this pre-surgical strategy into clinical settings, especially in combination with standard-of-care checkpoint inhibitors.

Alum-anchored intratumoral retention improves the tolerability and antitumor efficacy of type I interferon therapies

Effective antitumor immunity in mice requires activation of the type I interferon (IFN) response pathway. IFNα and IFNβ therapies have proven promising in humans, but suffer from limited efficacy and high toxicity. Intratumoral IFN retention ameliorates systemic toxicity, but given the complexity of IFN signaling, it was unclear whether long-term intratumoral retention of type I IFNs would promote or inhibit antitumor responses. To this end, we compared the efficacy of IFNα and IFNβ that exhibit either brief or sustained retention after intratumoral injection in syngeneic mouse tumor models. Significant enhancement in tumor retention, mediated by anchoring these IFNs to coinjected aluminum-hydroxide (alum) particles, greatly improved both their tolerability and efficacy. The improved efficacy of alum-anchored IFNs could be attributed to sustained pleiotropic effects on tumor cells, immune cells, and nonhematopoietic cells. Alum-anchored IFNs achieved high cure rates of B16F10 tumors upon combination with either anti-PD-1 antibody or interleukin-2. Interestingly however, these alternative combination immunotherapies yielded disparate T cell phenotypes and differential resistance to tumor rechallenge, highlighting important distinctions in adaptive memory formation for combinations of type I IFNs with other immunotherapies.

Tumor cell-based vaccine contributes to local tumor irradiation by eliciting a tumor model-dependent systemic immune response

Multimodal treatment approaches, such as radio-immunotherapy, necessitate regimen optimization and the investigation of the interactions of different modalities. The aim of this study was two-fold. Firstly, to select the most effective combination of irradiation and the previously developed tumor cell-based vaccine and then to provide insight into the immune response to the selected combinatorial treatment. The study was performed in immunologically different murine tumor models: B16F10 melanoma and CT26 colorectal carcinoma. The most effective combinatorial treatment was selected by comparing three different IR regimens and three different vaccination regimens. We determined the local immune response by investigating immune cell infiltration at the vaccination site and in tumors. Lastly, we determined the systemic immune response by investigating the amount of tumor-specific effector lymphocytes in draining lymph nodes. The selected most effective combinatorial treatment was 5× 5 Gy in combination with concomitant single-dose vaccination (B16F10) or with concomitant multi-dose vaccination (CT26). The combinatorial treatment successfully elicited a local immune response at the vaccination site and in tumors in both tumor models. It also resulted in the highest amount of tumor-specific effector lymphocytes in draining lymph nodes in the B16F10, but not in the CT26 tumor-bearing mice. However, the amount of tumor-specific effector lymphocytes was intrinsically higher in the CT26 than in the B16F10 tumor model. Upon the selection of the most effective combinatorial treatment, we demonstrated that the vaccine elicits an immune response and contributes to the antitumor efficacy of tumor irradiation. However, this interaction is multi-faceted and appears to be dependent on the tumor immunogenicity.

Local delivery of low-dose anti–CTLA-4 to the melanoma lymphatic basin leads to systemic T reg reduction and effector T cell activation

Preclinical studies show that locoregional CTLA-4 blockade is equally effective in inducing tumor eradication as systemic delivery, without the added risk of immune-related side effects. This efficacy is related to access of the CTLA-4 blocking antibodies to tumor-draining lymph nodes (TDLNs). Local delivery of anti–CTLA-4 after surgical removal of primary melanoma, before sentinel lymph node biopsy (SLNB), provides a unique setting to clinically assess the role of TDLN in the biological efficacy of locoregional CTLA-4 blockade. Here, we have evaluated the safety, tolerability, and immunomodulatory effects in the SLN and peripheral blood of a single dose of tremelimumab [a fully human immunoglobulin gamma-2 (IgG2) mAb directed against CTLA-4] in a dose range of 2 to 20 mg, injected intradermally at the tumor excision site 1 week before SLNB in 13 patients with early-stage melanoma (phase 1 trial; NCT04274816). Intradermal delivery was safe and well tolerated and induced activation of migratory dendritic cell (DC) subsets in the SLN. It also induced profound and durable decreases in regulatory T cell (T reg ) frequencies and activation of effector T cells in both SLN and peripheral blood. Moreover, systemic T cell responses against NY-ESO-1 or MART-1 were primed or boosted ( N = 7), in association with T cell activation and central memory T cell differentiation. These findings indicate that local administration of anti–CTLA-4 may offer a safe and promising adjuvant treatment strategy for patients with early-stage melanoma. Moreover, our data demonstrate a central role for TDLN in the biological efficacy of CTLA-4 blockade and support TDLN-targeted delivery methods.