Anti-PD-1 alone or in combination with anti-CTLA-4 for advanced melanoma patients with liver metastases

BACKGROUND

The combination of anti-PD-1 and anti-CTLA-4 has been associated with improvement in response and survival over anti-PD-1 monotherapy in unselected patients with advanced melanoma. Whether patients with liver metastases also benefit from the combination of anti-PD-1 and anti-CTLA-4 over anti-PD-1, is unclear. In this study, we sought to assess whether the combination of anti-PD-1 and anti-CTLA-4 leads to better response, progression-free survival and overall survival, compared with anti-PD-1 monotherapy for patients with liver metastases.

METHODS

We have conducted an international multicentre retrospective study. Patients with advanced melanoma with liver metastases treated with 1st line anti-PD1 monotherapy or with anti-CTLA-4 were included. The endpoints of this study were: objective response rate, progression-free survival and overall survival.

RESULTS

With a median follow-up from commencement of anti-PD-1 monotherapy or in combination with anti-CTLA-4 of 47 months (95% CI, 42-51), objective response rate was higher with combination therapy (47%) versus anti-PD-1 monotherapy (35%) (p = 0.0027), while progression-free survival and overall survival were not statistically different between both treatment groups. However, on multivariable analysis with multiple imputation for missing values and adjusting for predefined variables, combination of anti-PD1 and anti-CTLA-4 was associated with higher objective response (OR 2.21, 1.46 - 3.36; p < 0.001), progression-free survival (HR 0.73, 0.57 - 0.92; p = 0.009) and overall survival (HR 0.71, 0.54 - 0.94; p = 0.018) compared to anti-PD1 monotherapy.

CONCLUSIONS

Findings from this study will help guide treatment selection for patients who present with liver metastases, suggesting that combination therapy should be considered for this group of patients.

VEGF Inhibitors Improve Survival Outcomes in Patients with Liver Metastases across Cancer Types-A Meta-Analysis

BACKGROUND

Liver metastases are associated with poor prognosis across cancers. Novel treatment strategies to treat patients with liver metastases are needed. This meta-analysis aimed to assess the efficacy of vascular endothelial growth factor inhibitors in patients with liver metastases across cancers.

METHODS

A systematic search of PubMed, Cochrane CENTRAL, and Embase was performed between January 2000 and April 2023. Randomized controlled trials of patients with liver metastases comparing standard of care (systemic therapy or best supportive care) with or without vascular endothelial growth factor inhibitors were included in the study. Outcomes reported included progression-free survival and overall survival.

RESULTS

A total of 4445 patients with liver metastases from 25 randomized controlled trials were included in this analysis. The addition of vascular endothelial growth factor inhibitors to standard systemic therapy or best supportive care was associated with superior progression-free survival (HR = 0.49; 95% CI, 0.40-0.61) and overall survival (HR = 0.83; 95% CI, 0.74-0.93) in patients with liver metastases. In a subgroup analysis of patients with versus patients without liver metastases, the benefit with vascular endothelial growth factor inhibitors was more pronounced in the group with liver metastases (HR = 0.44) versus without (HR = 0.57) for progression-free survival, but not for overall survival.

CONCLUSION

The addition of vascular endothelial growth factor inhibitors to standard management improved survival outcomes in patients with liver metastasis across cancers.

Intratumoral CD16+ macrophages are associated with clinical outcomes of patients with metastatic melanoma treated with combination anti-PD-1 and anti-CTLA-4 therapy

PURPOSE

This study characterizes intratumoural macrophage populations within baseline melanoma biopsies from patients with advanced melanoma who received either anti-PD-1 monotherapy or combination with anti-CTLA-4. Particularly, FcγRIIIa (CD16) expressing macrophage densities were investigated for associations with response and progression-free survival.

EXPERIMENTAL DESIGN

Patients with advanced melanoma who received either anti-PD-1 monotherapy or combination anti-PD-1 and anti-CTLA-4 were retrospectively identified. Macrophage populations were analyzed within baseline melanoma biopsies via multiplex immunohistochemistry in relation to treatment outcomes.

RESULTS

Patients who responded to combination ICI contained higher CD16+ macrophage densities than those who did not respond (196 vs 7 cells/mm2; p = 0.0041). There was no diffidence in CD16+ macrophage densities in the PD-1 monotherapy-treated patients based on response (118 vs 89 cells/mm2; p = 0.29). A significant longer 3-year progression-free survival was observed in combination treated patients with high intratumoral densities of CD16+ macrophages compared to those with low densities (87% vs 42%, P=0.0056, n=40). No association was observed in anti-PD-1 monotherapy treated patients (50% vs 47%, P=0.4636, n=50). Melanoma biopsies with high densities of CD16+ macrophages contained upregulated gene expression of critical T-cell recruiting chemokines (CXCL9, CXCL10 and CXCL11).

CONCLUSION

Our data demonstrates that tumor environments enriched with CD16+ macrophages are favorable for response to combination anti-PD-1 and anti-CTLA-4 therapy but not anti-PD-1 monotherapy. This data provides a potential biomarker of response for combination immunotherapies in patients with metastatic melanoma.

The effect of organ-specific tumor microenvironments on response patterns to immunotherapy

Immunotherapy, particularly immune checkpoint inhibitors, have become widely used in various settings across many different cancer types in recent years. Whilst patients are often treated on the basis of the primary cancer type and clinical stage, recent studies have highlighted disparity in response to immune checkpoint inhibitors at different sites of metastasis, and their impact on overall response and survival. Studies exploring the tumor immune microenvironment at different organ sites have provided insights into the immune-related mechanisms behind organ-specific patterns of response to immunotherapy. In this review, we aimed to highlight the key learnings from clinical studies across various cancers including melanoma, lung cancer, renal cell carcinoma, colorectal cancer, breast cancer and others, assessing the association of site of metastasis and response to immune checkpoint inhibitors. We also summarize the key clinical and pre-clinical findings from studies exploring the immune microenvironment of specific sites of metastasis. Ultimately, further characterization of the tumor immune microenvironment at different metastatic sites, and understanding the biological drivers of these differences, may identify organ-specific mechanisms of resistance, which will lead to more personalized treatment approaches for patients with innate or acquired resistance to immunotherapy.

Unveiling the tumor immune microenvironment of organ-specific melanoma metastatic sites

Background

The liver is a known site of resistance to immunotherapy and the presence of liver metastases is associated with shorter progression-free and overall survival (OS) in melanoma, while lung metastases have been associated with a more favorable outcome. There are limited data available regarding the immune microenvironment at different anatomical sites of melanoma metastases. This study sought to characterize and compare the tumor immune microenvironment of liver, brain, lung, subcutaneous (subcut) as well as lymph node (LN) melanoma metastases.

Methods

We analyzed OS in 1924 systemic treatment-naïve patients with AJCC (American Joint Committee on Cancer) stage IV melanoma with a solitary site of organ metastasis. In an independent cohort we analyzed and compared immune cell densities, subpopulations and spatial distribution in tissue from liver, lung, brain, LN or subcut sites from 130 patients with stage IV melanoma.

Results

Patients with only liver, brain or bone metastases had shorter OS compared to those with lung, LN or subcutaneous and soft tissue metastases. Liver and brain metastases had significantly lower T-cell infiltration than lung (p=0.0116 and p=0.0252, respectively) and LN metastases (p=0.0116 and p=0.0252, respectively). T cells were further away from melanoma cells in liver than lung metastases (p=0.0335). Liver metastases displayed unique T-cell profiles, with a significantly lower proportion of programmed cell death protein-1+ T cells compared to all other anatomical sites (p<0.05), and a higher proportion of TIM-3+ T cells compared to LN (p=0.0004), subcut (p=0.0082) and brain (p=0.0128) metastases. Brain metastases had a lower macrophage density than subcut (p=0.0105), liver (p=0.0095) and lung (p<0.0001) metastases. Lung metastases had the highest proportion of programmed death ligand-1+ macrophages of the total macrophage population, significantly higher than brain (p<0.0001) and liver metastases (p=0.0392).

Conclusions

Liver and brain melanoma metastases have a significantly reduced immune infiltrate than lung, subcut and LN metastases, which may account for poorer prognosis and reduced immunotherapy response rates in patients with liver or brain metastases. Increased TIM-3 expression in liver metastases suggests TIM-3 inhibitor therapy as a potential therapeutic opportunity to improve patient outcomes.

Abstract 2221: Molecular analysis finds excision margin width predictive of recurrence in acral melanoma

Surgical excision with histologically clear margins results in cure of most melanoma patients. Involvement of the margins is associated with tumour recurrence and adverse outcomes. Determining whether or not the histological margins are involved by melanoma, particularly in situ melanoma, can be very difficult particularly in acral locations where insitu melanoma can be extremely subtle. This study sought to determine the proximity of acral melanoma in situ to the surgical excision margin using multiple methods including routine histopathological assessment, FISH (CCND1 amplification), and multiplex immunofluorescence (mIF: SOX10, p16, Cyclin D1 and PRAME) in primary acral melanomas with initially histopathologically reported clear excision margins of &gt;0.3mm (n=85). The clear excision margins determined by each modality were compared between those melanomas which recurred (n=47) and those which remained recurrence-free at last follow-up (median = 46 months, range = 1-260 months) (n=35). Histopathologically confirmed excision margin width was smaller in the tumours of patients who recurred (mean = 7.083mm vs 9.964mm, p = 0.0811). Intratumoural CCND1 amplification was increased in recurrence-free patients in comparison to recurrence patients (16.2% vs 7.7%). FISH and mIF confirmed the correlation of intratumoural CCND1 amplification with Cyclin D1 expression SOX10+ melanoma cells (p=0.0347). No correlations between recurrence status and Cyclin D1, PRAME or p16 expression levels in the tumour or epidermis were identified. In histopathologically normal epidermal tissue as assessed on H&E sections,Cyclin D1+, p16- and PRAME+ cells were classified as malignant cells when co-expressed with SOX10. Upon measuring the distance from the tumour margin to the nearest malignant cell, we found that malignant cells were closer to the tumour in recurrence patients in comparison to recurrence-free patients (mean = 7.324mm vs 9.464mm, p = 0.2735). These distances closely correlated with the excision margin width as determined via histopathological assessment (R2 = 0.7424, p&lt;0.0001). In conclusion, histological assessment, FISH and mIF determined excision margins are highly correlative in acral melanomas. Narrower excision margins were associated with local recurrence of melanoma.

Citation Format: Grace Heloise Attrill, Teresa A. Bailey, Trina Lum, Jordan W. Conway, Georgina V. Long, James S. Wilmott, Richard A. Scolyer. Molecular analysis finds excision margin width predictive of recurrence in acral melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2221.

VEGF inhibitors (VEGFi) activity in liver metastases (mets) regardless of primary cancer type: Meta-analysis and systematic review

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Background: Liver metastasis is a poor prognostic factor in several cancers and is associated with poor response to immunotherapy (IO) in melanoma and lung cancer. VEGFi have activity in hepatocarcinoma (HCC) and is hypothesized to be due the hypoxic microenvironment. Whether this is also true for liver mets is unknown. We sought to assess the efficacy of VEGFi in liver mets utilizing randomized-controlled clinical trials (RCTs) testing the efficacy of VEGFi, regardless of primary cancer site. Methods: Systematic searches of PubMed, Cochrane CENTRAL, and Embase were conducted from January 1, 2000, to January 1, 2022. All RCTs that compared a backbone of systemic therapy (chemotherapy [chemo] and/or IO and/or targeted therapy [TT]) or best supportive care (BSC) with vs without VEGFi in patients (pts) with liver mets from any cancer were selected. HCC trials were excluded. Study design, cancer type, number of pts, lines of treatment, study drugs and hazard ratios (HRs) with 95% CIs for overall survival (OS) and progression-free survival (PFS) were extracted. Pooled effects of VEGFi in pts with liver mets across different cancer types were estimated using random effect model with inverse variance. Heterogeneity between studies was assessed by I2 statistics. Sensitivity analyses were performed considering prespecified subgroups of trials. Results: 3170 pts with liver mets from 19 RCTs were included in this meta-analysis: 8 colorectal cancer, 4 non-small cell lung cancer, 4 renal cell cancer & urothelial cancer, 1 pancreatic cancer, 1 GIST and 1 gastric cancer. Backbone systemic therapy in these trials included: chemo (11), TT (2), IO (2), chemo+IO (1), chemo+TT (1); and 2 BSC trials. Moderate heterogeneity between studies for both PFS (I2= 55%) and OS (I2= 46%) was seen. The addition of VEGFi to standard systemic therapy or BSC was associated with superior PFS (HR = 0.61; 95% CI, 0.50-0.74; p < 0.0001) and OS (HR = 0.86; 95%CI, 0.76-0.99; p = 0.0334) in pts with liver mets, regardless of whether pts had only liver mets or concurrent other sites of mets. In the subset of RCTs with data on pts without liver mets, the benefit with VEGFi was more pronounced in patients with liver mets (HR = 0.56) vs those without liver mets (HR = 0.64) for PFS, but not for OS. Conclusions: The addition of VEGFi to standard management improved survival outcomes in pts with liver mets across different cancer types and warrants further investigation. VEGFi added to IO may be effective in pts with resistant liver mets.

Higher proportions of CD39+ tumor-resident cytotoxic T cells predict recurrence-free survival in patients with stage III melanoma treated with adjuvant immunotherapy

BACKGROUND

Adjuvant immune checkpoint inhibitor (ICI) immunotherapies have significantly reduced the recurrence rate in high-risk patients with stage III melanoma compared with surgery alone. However, 48% of anti-PD-1-treated patients will develop recurrent disease within 4 years. There is a need to identify biomarkers of recurrence after adjuvant ICI to enable identification of patients in need of alternative treatment strategies. As cytotoxic T cells are critical for the antitumor response to anti-PD-1, we sought to determine whether specific subsets were predictive of recurrence in anti-PD-1-treated high-risk patients with stage III melanoma.

METHODS

Associations with recurrence in patients with stage III melanoma were sought by analyzing resection specimens (n=103) taken prior to adjuvant nivolumab/pembrolizumab±low-dose/low-interval ipilimumab. Multiplex immunohistochemistry was used to quantify intratumoral CD8+ T-cell populations using phenotypical markers CD39, CD103, and PD-1.

RESULTS

With a median follow-up of 19.3 months, 37/103 (36%) of patients had a recurrence. Two CD8+ T-cell subpopulations were significantly associated with recurrence. First, CD39+ tumor-resident memory cells (CD39+CD103+PD-1+CD8+ (CD39+ Trm)) comprised a significantly higher proportion of CD8+ T cells in recurrence-free patients (p=0.0004). Conversely, bystander T cells (CD39-CD103-PD-1-CD8+) comprised a significantly greater proportion of T cells in patients who developed recurrence (p=0.0002). Spatial analysis identified that CD39+ Trms localized significantly closer to melanoma cells than bystander T cells. Multivariable analysis confirmed significantly improved recurrence-free survival (RFS) in patients with a high proportion of intratumoral CD39+ Trms (1-year RFS high 78.1% vs low 49.9%, HR 0.32, 95% CI 0.15 to 0.69), no complete lymph node dissection performed, and less advanced disease stage (HR 2.85, 95% CI 1.13 to 7.19, and HR 1.29, 95% CI 0.59 to 2.82). The final Cox regression model identified patients who developed recurrence with an area under the curve of 75.9% in the discovery cohort and 69.5% in a separate validation cohort (n=33) to predict recurrence status at 1 year.

CONCLUSIONS

Adjuvant immunotherapy-treated patients with a high proportion of CD39+ Trms in their baseline melanoma resection have a significantly reduced risk of melanoma recurrence. This population of T cells may not only represent a biomarker of RFS following anti-PD-1 therapy, but may also be an avenue for therapeutic manipulation and enhancing outcomes for immunotherapy-treated patients with cancer.

Validation of an Accurate Automated Multiplex Immunofluorescence Method for Immuno-Profiling Melanoma

Multiplex immunofluorescence staining enables the simultaneous detection of multiple immune markers in a single tissue section, and is a useful tool for the identification of specific cell populations within the tumour microenvironment. However, this technology has rarely been validated against standard clinical immunohistology, which is a barrier for its integration into clinical practice. This study sought to validate and investigate the accuracy, precision and reproducibility of a multiplex immunofluorescence compared with immunohistochemistry (IHC), including tissue staining, imaging and analysis, in characterising the expression of immune and melanoma markers in both the tumour and its microenvironment. Traditional chromogenic IHC, single-plex immunofluorescence and multiplex immunofluorescence were each performed on serial tissue sections of a formalin-fixed paraffin-embedded (FFPE) tissue microarray containing metastatic melanoma specimens from 67 patients. The panel included the immune cell markers CD8, CD68, CD16, the immune checkpoint PD-L1, and melanoma tumour marker SOX10. Slides were stained with the Opal^™ 7 colour Kit (Akoya Biosciences) on the intelliPATH autostainer (Biocare Medical) and imaged using the Vectra 3.0.5 microscope. Marker expression was quantified using Halo v.3.2.181 (Indica Labs). Comparison of the IHC and single-plex immunofluorescence revealed highly significant positive correlations between the cell densities of CD8, CD68, CD16, PD-L1 and SOX10 marker positive cells (Spearman’s rho = 0.927 to 0.750, p < 0.0001). Highly significant correlations were also observed for all markers between single-plex immunofluorescence and multiplex immunofluorescence staining (Spearman’s rho >0.9, p < 0.0001). Finally, correlation analysis of the three multiplex replicates revealed a high degree of reproducibility between slides (Spearman’s rho >0.940, p < 0.0001). Together, these data highlight the reliability and validity of multiplex immunofluorescence in accurately profiling the tumour and its associated microenvironment using FFPE metastatic melanoma specimens. This validated multiplex panel can be utilised for research evaluating melanoma and its microenvironment, such as studies performed to predict patient response or resistance to immunotherapies.

Abstract 2762: Spatial distribution and immune cell infiltration at different sites of melanoma metastases (mets)

Purpose: The site of metastasis in advanced melanoma patients (pts) influences pt response to immunotherapy and overall prognosis. Liver mets are particularly resistant to immunotherapy and their presence often confers shorter survival and reduced response rates. This study characterised and compared the tumor immune microenvironment of melanoma mets at different anatomical sites.

Methods: T-cell and myeloid cell markers were stained using multiplex IHC on FFPE samples from 136 untreated metastatic melanoma pts, from 5 anatomical sites (liver, lung, brain, subcutaneous, and lymph node (LN)). Cell densities, subpopulations and the spatial distribution of cells were compared between sites.

Results: CD3+ T cell infiltration was less dense in the liver (med = 154.3 cells/mm2) and brain mets (med = 180.7 cells/mm2) v's lung (med = 434.7 cells/mm2) and LN mets (med = 504.8 cells/mm2) (p&lt;0.05), and T-cells were further away from melanoma cells in liver v's lung mets (med distance = 83µm v's 57µm respectively; P&lt;0.05). The liver displayed a unique T-cell profile, with a significantly lower proportion of CD3+ T cells expressing PD-1 (med = 0.7%) compared to all other sites (P&lt;0.05) while brain mets expressed the highest proportion of PD-1+ T cells (med = 8.9%). There were higher proportions of Tim3+ T cells in liver (10.7%) and lung mets (12.9%) v's brain, subcut and LN mets (P&lt;0.05). Specifically, in liver mets CD3+ T cells within 20um of a melanoma cell had a significantly higher expression of Tim3 (med = 18.57%) v's PD-1 (med = 2%). Brain mets had the lowest density of CD68+ macrophages (med = 33 cells/mm2) v's lung (med = 372 cells/mm2), liver (med = 290 cells/mm2) and Subcut mets (med = 154 cells/mm2). Lung mets also had the highest proportion of PD-L1+ macrophages (med = 18.73%) compared to liver (med = 5.2%) and brain mets (med = 0.65%). While the most highly expressed T cell population varied between sites, CD16+ macrophages were consistently the highest expressed macrophage subpopulation regardless of metastatic site.

Conclusion: These data suggest that liver mets are less immunogenic, with fewer T cells and greater distances between CD3+ T cells and melanoma cells, and may account for the poor prognosis of melanoma patients with liver metastases and their reduced response rate to immunotherapy compared to other mets. While liver mets have reduced PD-1 expression, higher Tim3 expression in the liver may provide a therapeutic opportunity to improve outcomes for pts with liver mets by using anti-TIM3 immunotherapy. Overall, these data provide novel insights into the site-specific biology of melanoma mets, heterogeneity in the tumor immune microenvironment, and the need for site specific biomarkers to be considered when selecting treatment targets.

Citation Format: Jordan W. Conway, Robert V. Rawson, James S. Wilmott, Georgina V. Long, Richard A. Scolyer, Inês Pires Da Silva. Spatial distribution and immune cell infiltration at different sites of melanoma metastases (mets) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2762.

Comprehensive analysis of cutaneous and uveal melanoma liver metastases

BACKGROUND

The profound disparity in response to immune checkpoint blockade (ICB) by cutaneous melanoma (CM) and uveal melanoma (UM) patients is not well understood. Therefore, we characterized metastases of CM and UM from the same metastatic site (liver), in order to dissect the potential underlying mechanism in differential response on ICB.

METHODS

Tumor liver samples from CM (n=38) and UM (n=28) patients were analyzed at the genomic (whole exome sequencing), transcriptional (RNA sequencing) and protein (immunohistochemistry and GeoMx Digital Spatial Profiling) level.

RESULTS

Comparison of CM and UM metastases from the same metastatic site revealed that, although originating from the same melanocyte lineage, CM and UM differed in somatic mutation profile, copy number profile, tumor mutational burden (TMB) and consequently predicted neoantigens. A higher melanin content and higher expression of the melanoma differentiation antigen MelanA was observed in liver metastases of UM patients. No difference in B2M and human leukocyte antigen-DR (HLA-DR) expression was observed. A higher expression of programmed cell death ligand 1 (PD-L1) was found in CM compared with UM liver metastases, although the majority of CM and UM liver metastases lacked PD-L1 expression. There was no difference in the extent of immune infiltration observed between CM and UM metastases, with the exception of a higher expression of CD163 (p<0.0001) in CM liver samples. While the extent of immune infiltration was similar for CM and UM metastases, the ratio of exhausted CD8 T cells to cytotoxic T cells, to total CD8 T cells and to Th1 cells, was significantly higher in UM metastases.

CONCLUSIONS

While TMB was different between CM and UM metastases, tumor immune infiltration was similar. The greater dependency on PD-L1 as an immune checkpoint in CM and the identification of higher exhaustion ratios in UM may both serve as explanations for the difference in response to ICB. Consequently, in order to improve current treatment for metastatic UM, reversal of T cell exhaustion beyond programmed cell death 1 blockade should be considered.