Metastasis-specific patterns of response and progression with anti-PD-1 treatment in metastatic melanoma

Radiomic analysis of patient and interorgan heterogeneity in response to immunotherapies and BRAF-targeted therapy in metastatic melanoma

Variability in treatment response may be attributable to organ-level heterogeneity in tumor lesions. Radiomic analysis of medical images can elucidate non-invasive biomarkers of clinical outcome. Organ-specific radiomic comparison across immunotherapies and targeted therapies has not been previously reported. We queried the UPMC Hillman Cancer Center registry for patients with metastatic melanoma (MEL) treated with immune checkpoint inhibitors (ICI) (anti-programmed cell death protein-1 (PD-1)/cytotoxic T-lymphocyte associated protein 4 (CTLA-4) (ipilimumab+nivolumab; I+N) or anti-PD-1 monotherapy) or BRAF-targeted therapy. The best overall response was measured using Response Evaluation Criteria in Solid Tumors V.1.1. Lesions were segmented into discrete volume-of-interest with 400 radiomics features extracted. Overall and organ-specific machine-learning models were constructed to predict disease control (DC) versus progressive disease (PD) using XGBoost. 291 patients with MEL were identified, including 242 ICI (91 I+N, 151 PD-1) and 49 BRAF. 667 metastases were analyzed, including 541 ICI (236 I+N, 305 PD-1) and 126 BRAF. Across cohorts, baseline demographics included 39-47% women, 24%-29% M1C, 24-46% M1D, and 61-80% with elevated lactate dehydrogenase. Among ICI patients experiencing DC, the organs with the greatest reduction were liver (-66%±8%; mean±SEM) and lung (-63%±5%). For patients with multiple same-organ target lesions, the highest interlesion heterogeneity was observed in brain among patients who received ICI while no intraorgan heterogeneity was observed in BRAF. 221 ICI patients were included for radiomic modeling, consisting of 86 I+N and 135 PD-1. Models consisting of optimized radiomic signatures classified DC/PD across I+N (area under curve (AUC)=0.85) and PD-1 (0.71) and within individual organ sites (AUC=0.72~0.94). Integration of clinical variables improved the models' performance. Comparison of models between treatments and across organ sites suggested mostly non-overlapping DC or PD features. Skewness, kurtosis, and informational measure of correlation (IMC) were among the radiomic features shared between overall response models. Kurtosis and IMC were also used by multiple organ-site models. In conclusion, differential organ-specific response was observed across BRAF and ICI with within organ heterogeneity observed for ICI but not for BRAF. Radiomic features of organ-specific response demonstrated little overlap. Integrating clinical factors with radiomics improves the prediction of disease course outcome and prediction of tumor heterogeneity.

Response and outcome of patients with melanoma skin metastases and immune checkpoint inhibition

It is known, that different metastatic organ systems respond differently to immune checkpoint inhibitors (ICIs). In this study, we aimed to investigate the extent to which skin/subcutaneous metastases respond to ICI or targeted therapies (TTs) and whether the response rate differs from that of distant metastases in the same patient. Patients with melanoma diagnosed between January 2021 and September 2023 with at least one skin/subcutaneous metastasis who had received therapy with ICI or TT in an advanced setting were included in the analysis. Best overall response (BOR) was classified according to the revised response evaluation criteria in solid tumors (RECIST). The BOR of skin metastases and visceral metastases to ICI and TT was compared using the chi-square test. Skin metastases treated with ICI a first-line setting showed an overall response rate (ORR) of 44.1%. In contrast, visceral metastases had a higher ORR of 51.1%. However, the difference was not statistically significant (p = .77). Regarding TT, the ORR for skin metastases was 57.1%, compared to 38.5% for visceral metastases (p = .59). Interestingly, the ORR for skin/subcutaneous metastases was notably lower with ICI compared to visceral metastases, in contrast to patients who underwent TT. Skin metastases showed a poorer response to ICI than visceral metastases. Therefore, careful monitoring is recommended to detect non-response early in patients with skin metastases as skin metastases may have a worse response than TT. A larger cohort is needed for a comprehensive analysis and confirmation of our results.

Single-Nuclei Transcriptome Profiling Reveals Intra-Tumoral Heterogeneity and Characterizes Tumor Microenvironment Architecture in a Murine Melanoma Model

Malignant melanoma is an aggressive cancer, with a high risk of metastasis and mortality rates, characterized by cancer cell heterogeneity and complex tumor microenvironment (TME). Single cell biology is an ideal and powerful tool to address these features at a molecular level. However, this approach requires enzymatic cell dissociation that can influence cellular coverage. By contrast, single nucleus RNA sequencing (snRNA-seq) has substantial advantages including compatibility with frozen samples and the elimination of a dissociation-induced, transcriptional stress response. To better profile and understand the functional diversity of different cellular components in melanoma progression, we performed snRNA-seq of 16,839 nuclei obtained from tumor samples along the growth of murine syngeneic melanoma model carrying a BRAFV600E mutation and collected 9 days or 23 days after subcutaneous cell injection. We defined 11 different subtypes of functional cell clusters among malignant cells and 5 different subsets of myeloid cells that display distinct global transcriptional program and different enrichment in early or advanced stage of tumor growth, confirming that this approach was useful to accurately identify intratumor heterogeneity and dynamics during tumor evolution. The current study offers a deep insight into the biology of melanoma highlighting TME reprogramming through tumor initiation and progression, underlying further discovery of new TME biomarkers which may be potentially druggable.

Site-Specific Response and Resistance Patterns in Patients with Advanced Non-Small-Cell Lung Cancer Treated with First-Line Systemic Therapy

Patients with advanced NSCLC have heterogenous responses to immune checkpoint inhibitors (ICIs) with or without chemotherapy. In NSCLC, the impact of the distribution of metastatic sites and the response to systemic therapy combinations remain poorly understood. In a retrospective cohort study of patients with unresectable stage III/IV NSCLC who received first-line systemic therapy, we sought to assess the association between the site of metastases with patterns of response and progression. Data regarding demographics, tumour characteristics (including site, size, and volume of metastases), treatment, and outcomes were examined at two cancer care centres. The endpoints included organ site-specific response rate, objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). Two-hundred and eighty-five patients were included in the analysis. In a multivariate analysis, patients with bone metastases had a reduced ORR, PFS, and OS. Primary resistance was also more likely in patients with bone metastases. Patients with bone or liver metastases had a shorter OS when receiving ICIs with or without chemotherapy, but not with chemotherapy alone, suggesting an immunological basis for therapeutic resistance. A directed assessment of the tumour microenvironment in these locations and a deeper understanding of the drivers of organ-specific resistance to immunotherapy are critical to optimise novel combination therapies and sequencing in these patients.

Enhanced oral versus flank lymph node T cell response parallels anti-PD1 efficacy in head and neck cancer

OBJECTIVES

Understanding head and neck tissue specific immune responses is important for elucidating immunotherapy resistance mechanisms to head and neck squamous cell carcinoma (HNSCC). In this study, we aimed to investigate HNSCC-specific immune response differences between oral and subcutaneous flank tumor transplantation in preclinical models.

MATERIALS AND METHODS

The MOC1 syngeneic mouse oral carcinoma cell line or versions expressing either the H2Kb-restricted SIINFEKL peptide from ovalbumin (MOC1OVA) or ZsGreen (MOC1ZsGreen) were inoculated into mouse oral mucosa (buccal space) or subcutaneous flank and compared for immune cell kinetics in tumors and tumor-draining lymph nodes (TDLNs) and for anti-PD1 response.

RESULTS

Compared to subcutaneous flank tumors, orthotopic oral MOC1OVA induced a higher number of OVA-specific T cells, PD1 + or CD69 + activated OVA-specific T cells in both primary tumors and TDLNs. Tumors were also larger in the flank site and CD8 depletion eliminated the difference in tumor weight between the two sites. Oral versus flank SIINFEKL peptide vaccination showed enhanced TDLN lymphocyte response in the former site. Notably, cDC1 from oral TDLN showed enhanced antigen uptake and co-stimulatory marker expression, resulting in elicitation of an increased antigen specific T cell response and increased activated T cells. Parental MOC1 in the oral site showed increased endogenous antigen-reactive T cells in TDLNs and anti-PD1 blockade rejected oral MOC1 tumors but not subcutaneous flank MOC1.

CONCLUSION

Collectively, we find distinct immune responses between orthotopic oral and heterotopic subcutaneous models, including priming by cDC1 in TDLN, revealing important implications for head and neck cancer preclinical studies.

Radiomic analysis of patient and inter-organ heterogeneity in response to immunotherapies and BRAF targeted therapy in metastatic melanoma

Background

Variability in treatment response may be attributable to organ-level heterogeneity in tumor lesions. Radiomic analysis of medical images can elucidate non-invasive biomarkers of clinical outcome. Organ-specific radiomic comparison across immunotherapies and targeted therapies has not been previously reported.

Methods

We queried UPMC Hillman Cancer Center registry for patients with metastatic melanoma (MEL) treated with immune checkpoint inhibitors (ICI) (anti-PD1/CTLA4 [ipilimumab+nivolumab; I+N] or anti-PD1 monotherapy) or BRAF targeted therapy. Best overall response was measured using RECIST v1.1. Lesions were segmented into discrete volume-of-interest with 400 radiomics features extracted. Overall and organ-specific machine-learning models were constructed to predict disease control (DC) versus progressive disease (PD) using XGBoost.

Results

291 MEL patients were identified, including 242 ICI (91 I+N, 151 PD1) and 49 BRAF. 667 metastases were analyzed, including 541 ICI (236 I+N, 305 PD1) and 126 BRAF. Across cohorts, baseline demographics included 39-47% female, 24-29% M1C, 24-46% M1D, and 61-80% with elevated LDH. Among patients experiencing DC, the organs with the greatest reduction were liver (-88%±12%, I+N; mean±S.E.M.) and lung (-72%±8%, I+N). For patients with multiple same-organ target lesions, the highest inter-lesion heterogeneity was observed in brain among patients who received ICI while no intra-organ heterogeneity was observed in BRAF. 267 patients were kept for radiomic modeling, including 221 ICI (86 I+N, 135 PD1) and 46 BRAF. Models consisting of optimized radiomic signatures classified DC/PD across I+N (AUC=0.85) and PD1 (0.71) and within individual organ sites (AUC=0.72∼0.94). Integration of clinical variables improved the models' performance. Comparison of models between treatments and across organ sites suggested mostly non-overlapping DC or PD features. Skewness, kurtosis, and informational measure of correlation (IMC) were among the radiomic features shared between overall response models. Kurtosis and IMC were also utilized by multiple organ-site models.

Conclusions

Differential organ-specific response was observed across BRAF and ICI with within organ heterogeneity observed for ICI but not for BRAF. Radiomic features of organ-specific response demonstrated little overlap. Integrating clinical factors with radiomics improves the prediction of disease course outcome and prediction of tumor heterogeneity.

Single-cell RNA sequencing in melanoma: what have we learned so far?

Over the past decade, there have been remarkable improvements in the treatment and survival rates of melanoma patients. Treatment resistance remains a persistent challenge, however, and is partly attributable to intratumoural heterogeneity. Melanoma cells can transition through a series of phenotypic and transcriptional cell states that vary in invasiveness and treatment responsiveness. The diverse stromal and immune contexture of the tumour microenvironment also contributes to intratumoural heterogeneity and disparities in treatment response in melanoma patients. Recent advances in single-cell sequencing technologies have enabled a more detailed understanding of melanoma heterogeneity and the underlying transcriptional programs that regulate melanoma cell diversity and behaviour. In this review, we examine the concept of intratumoural heterogeneity and the challenges it poses to achieving long-lasting treatment responses. We focus on the significance of next generation single-cell sequencing in advancing our understanding of melanoma diversity and the unique insights gained from single-cell studies.

Predictive Biomarkers for Immune-Checkpoint Inhibitor Treatment Response in Patients with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) has one of the highest mortality rates among solid cancers. Late diagnosis and a lack of efficacious treatment options contribute to the dismal prognosis of HCC. Immune checkpoint inhibitor (ICI)-based immunotherapy has presented a new milestone in the treatment of cancer. Immunotherapy has yielded remarkable treatment responses in a range of cancer types including HCC. Based on the therapeutic effect of ICI alone (programmed cell death (PD)-1/programmed death-ligand1 (PD-L)1 antibody), investigators have developed combined ICI therapies including ICI + ICI, ICI + tyrosine kinase inhibitor (TKI), and ICI + locoregional treatment or novel immunotherapy. Although these regimens have demonstrated increasing treatment efficacy with the addition of novel drugs, the development of biomarkers to predict toxicity and treatment response in patients receiving ICI is in urgent need. PD-L1 expression in tumor cells received the most attention in early studies among various predictive biomarkers. However, PD-L1 expression alone has limited utility as a predictive biomarker in HCC. Accordingly, subsequent studies have evaluated the utility of tumor mutational burden (TMB), gene signatures, and multiplex immunohistochemistry (IHC) as predictive biomarkers. In this review, we aim to discuss the current state of immunotherapy for HCC, the results of the predictive biomarker studies, and future direction.

Metastatic sites and lesion numbers cooperated to predict efficacy of PD-1 inhibitor-based combination therapy for patients with metastatic colorectal cancer

BACKGROUND

Limited data have been used to evaluate the efficacy of immunotherapy in metastatic colorectal cancer (mCRC). Furthermore, potential markers that can be used to identify responding patients and to further improve efficacy have not been fully explored.

METHODS AND RESULTS

In our study, we included a total of 97 patients with mCRC, who each received programmed death-1 (PD-1) inhibitor-based combination therapy at our center. All 12 hypermutated patients benefited from immunotherapy, with median progression-free survival (mPFS) reaching 28.3 months, regardless of liver metastasis. The objective response rate (ORR) of non-hypermutated patients was 16.5% (14/85), with an mPFS of 4.0 months. For non-hypermutated patients, multivariate analysis revealed that the combination of liver metastasis and baseline lesion number significantly stratified response and survival. The lesion-based analysis indicated that the lymph node was the most responsive, followed by the peritoneum and lung, with liver metastasis being the least responsive. None of the patients (0/7) with negative programmed ligand-1 (PD-L1) expression responded, and positive PD-L1 expression may serve as a biomarker (mPFS 5.7 vs. 2.2 months, p = 0.002) that can be used to further guide treatment in non-hypermutated mCRC with liver metastasis (CRLMs).

CONCLUSION

Patients with hypermutated mCRC benefited significantly from immunotherapy, whereas the non-hypermutated cohort with liver metastasis and numerous lesions showed less benefit. The lesion sites reflected varying levels of efficacy, among which PD-L1 potentially cooperated to guide the immunotherapy of CRLMs.

Efficacy of immunotherapy for melanoma brain metastases in patients with concurrent corticosteroid exposure

Aim: Immune checkpoint inhibitor (ICI) efficacy is undefined for melanoma brain metastases (MBM) with concurrent corticosteroid exposure. Materials & methods: We retrospectively evaluated patients with untreated MBM who received corticosteroids (≥1.5 mg dexamethasone equivalent) within 30 days of ICI. mRECIST criteria and Kaplan-Meier methods defined intracranial progression-free survival (iPFS). The lesion size-response association was evaluated with repeated measures modeling. Results: A total of 109 MBM were evaluated. The patient level intracranial response rate was 41%. Median iPFS was 2.3 months and overall survival was 13.4 months. Larger lesions were more likely to progress, with diameter >2.05 cm most predictive of progression (OR: 18.9; 95% CI: 2.6-139.5; p = 0.004). There was no difference in iPFS with steroid exposure pre- versus post-ICI initiation. Conclusion: In the largest reported ICI+corticosteroid cohort, we identify size dependent MBM response.

Five‐year survival and clinical correlates among patients with advanced non‐small cell lung cancer, melanoma and renal cell carcinoma treated with immune check‐point inhibitors in Australian tertiary oncology centres

AIMS

There is robust trial evidence for improved overall survival (OS) with immunotherapy in advanced solid organ malignancies. The real-world long-term survival data and the predictive variables are not yet known. Our aim was to evaluate factors associated with 3-year and 5-year OS for patients treated with immune checkpoint inhibitors (ICIs).

METHODS

We performed a retrospective study of patients who received ICIs as management of advanced solid organ malignancies in two tertiary Australian oncology centres from 2012-2017. Data pertaining to clinical characteristics, metastatic disease burden, immune-related adverse events (IRAEs) and tumour responses were collected and their relationship to survival examined.

RESULTS

In this analysis of 264 patients, 202 (76.5%) had melanoma, 46 (17.4%) had non-small cell lung cancer (NSCLC), 12 (4.5%) had renal cell carcinoma (RCC) and 4 (1.5%) had mesothelioma. The 5-year OS rates were 42.1% in patients with melanoma, 19.6% with NSCLC, 75% with RCC, and none of the mesothelioma patients were alive at 5 years. In multivariate analysis, an ECOG score of 0 (Hazard ratio [HR] 0.39; 95% confidence interval [CI] 0.23-0.66; p < 0.001) and the occurrence of IRAE's of any grade (HR 0.61; 95% CI 0.37-0.95; p = 0.05) were associated with better 5-year survival. The presence of bone metastases (HR 1.62; 95% CI 1.03-2.82; p = 0.05) and liver metastases (HR 1.76; 95% CI 1.07-2.89; p = 0.03) were associated with worse 5-year survival.

CONCLUSIONS

These results support the long-term benefits of immunotherapy that in some patients, extend to at least 5 years. ECOG performance status of 0 and the occurrence of irAEs are associated with better long-term survival. Survival is significantly influenced by metastatic site and cancer type. These predictive clinical correlates aid discussions and planning in the delivery of ICIs to patients.

Towards Accurate and Precise Image-Guided Radiotherapy: Clinical Applications of the MR-Linac

Advances in image-guided radiotherapy have brought about improved oncologic outcomes and reduced toxicity. The next generation of image guidance in the form of magnetic resonance imaging (MRI) will improve visualization of tumors and make radiation treatment adaptation possible. In this review, we discuss the role that MRI plays in radiotherapy, with a focus on the integration of MRI with the linear accelerator. The MR linear accelerator (MR-Linac) will provide real-time imaging, help assess motion management, and provide online adaptive therapy. Potential advantages and the current state of these MR-Linacs are highlighted, with a discussion of six different clinical scenarios, leading into a discussion on the future role of these machines in clinical workflows.

Hyperprogressive disease during PD-1 blockade in patients with advanced gastric cancer

BACKGROUND

Investigations for programmed cell death-1 (PD-1) blockade-induced hyperprogressive disease (HPD) have not been stringently conducted in patients with advanced gastric cancer (AGC). We explored the occurrence of HPD and its clinical implications in patients with AGC and treated with PD-1 inhibitors.

METHODS

We enrolled 169 patients with AGC and treated with either the PD-1 blockade (nivolumab or pembrolizumab; N = 112) or irinotecan monotherapy (N = 57) as a single agent. Tumour growth dynamics based on tumour growth kinetics and tumour growth rate (TGR) and time to treatment failure were analysed to define HPD. The incidence, clinical consequences and predictive markers of HPD were investigated.

RESULTS

The optimal criteria for HPD were 4-fold increases in both tumour growth kinetics and TGR ratios and a 40% increase in TGR based on the analysis for patients treated with irinotecan. In total, 10.7% (12/112) of patients experienced HPD after PD-1 inhibitor treatment. Patients with HPD had both shorter progression-free survival (hazard ratio: 2.318; 95% confidence interval: 1.205-4.460) and overall survival (hazard ratio: 2.542; 95% confidence interval: 1.314-4.918) than patients with progressive disease without HPD, losing opportunities for subsequent systemic treatments. Although other variables including PD-L1 expression were not associated with the occurrence of HPD, hypoalbuminemia (<3.25 mg/dL) at baseline was significantly associated with the occurrence of HPD (P < 0.001) and inferior survival outcomes.

CONCLUSIONS

HPD occurs in a proportion of patients with AGC and treated with PD-1 inhibitors. PD-1 inhibitor-induced HPD is associated with worse outcome, loss of eligibility for subsequent treatment and hypoalbuminemia, warranting further investigation.

Melanoma Metastases to the Adrenal Gland Are Highly Resistant to Immune Checkpoint Inhibitors

BACKGROUND

Adrenal gland metastases (AGMs) are common in advanced-stage melanoma, occurring in up to 50% of patients. The introduction of immune checkpoint inhibitors (ICIs) has markedly altered the outcome of patients with melanoma. However, despite significant successes, anecdotal evidence has suggested that treatment responses in AGMs are significantly lower than in other metastatic sites. We sought to investigate whether having an AGM is associated with altered outcomes and whether ICI responses are dampened in the adrenal glands.

PATIENTS AND METHODS

We retrospectively compared ICI responses and overall survival (OS) in 68 patients with melanoma who were diagnosed with an AGM and a control group of 100 patients without AGMs at a single institution. Response was determined using RECIST 1.1. OS was calculated from time of ICI initiation, anti-PD-1 initiation, initial melanoma diagnosis, and stage IV disease diagnosis. Tumor-infiltrating immune cells were characterized in 9 resected AGMs using immunohistochemical analysis.

RESULTS

Response rates of AGMs were significantly lower compared with other metastatic sites in patients with AGMs (16% vs 22%) and compared with those without AGMs (55%). Patients with AGMs also had significantly lower median OS compared with those without AGMs (3.1 years vs not reached, respectively). We further observed that despite this, AGMs exhibited high levels of tumor-infiltrating immune cells.

CONCLUSIONS

In this cohort of patients with melanoma, those diagnosed with an AGM had lower ICI response rates and OS. These results suggest that tissue-specific microenvironments of AGMs present unique challenges that may require novel, adrenal gland-directed therapies or surgical resection.

Response to Immune Checkpoint Inhibitors in Recurrent or Metastatic Esophageal Squamous Cell Carcinoma May Be Affected by Tumor Sites

INTRODUCTION

Heterogeneous tumor response has been reported in cancer patients treated with immune checkpoint inhibitors (ICIs). This study investigated whether the tumor site is associated with the response to ICIs in patients with recurrent or metastatic esophageal squamous cell carcinoma (ESCC).

METHODS

Patients with ESCC who had measurable tumors in the liver, lung, or lymph node (LN) according to the response evaluation criteria in solid tumors (RECIST) 1.1 and received ICIs at 2 medical centers in Taiwan were enrolled. In addition to RECIST 1.1, tumor responses were determined per individual organ basis according to organ-specific criteria modified from RECIST 1.1. Fisher test or χ2 test was used for statistical analysis.

RESULTS

In total, 37 patients were enrolled. The overall response rate per RECIST 1.1 was 13.5%. Measurable tumors in the LN, lung, and liver were observed in 26, 17, and 13 patients, respectively. The organ-specific response rates were 26.9%, 29.4%, and 15.4% for the LN, lung, and liver tumors, respectively (p = 0.05). The organ-specific disease control rates were 69.2%, 52.9%, and 21.1% for the LN, lung, and liver tumors, respectively (p = 0.024). Five (27.8%) among 18 patients harboring at least 2 involved organs had heterogeneous tumor response.

CONCLUSION

The response and disease control to ICIs may differ in ESCC tumors located at different metastatic sites, with a lesser likelihood of response and disease control in metastatic liver tumors than in tumors located at the LNs and lung.

Adjuvant PD-1 inhibitor versus high-dose interferon α-2b for Chinese patients with cutaneous and acral melanoma: A retrospective cohort analysis

The clinical efficacy of PD-1 inhibitors as an adjuvant treatment for Asian melanoma patients has not yet been determined. This retrospective study analyzed the clinical data of 90 Chinese patients with completely resected, stage III cutaneous or acral melanoma who received either adjuvant PD-1 inhibitor or high-dose interferon α-2b (HDI). Anti-PD-1 treatment resulted in significantly longer RFS and DMFS than HDI in cutaneous melanoma patients, with hazard ratios (HRs) (anti-PD-1 versus HDI) of 0.402 (95% CI, 0.183-0.886) and 0.324 (95%CI, 0.122 to 0.861) for RFS and DMFS, respectively. However, adjuvant anti-PD-1 treatment had no advantage over HDI in acral melanoma patients with HRs (anti-PD-1 versus HDI) of 1.204 (95% CI, 0.521 to 2.781) and 1.968(95% CI, 0.744-5.209) for RFS and DMFS, respectively. Adjuvant anti-PD-1 treatment yielded a significantly better prognosis than HDI in Chinese patients with stage IIIB/C cutaneous melanoma, but a significant difference was not observed in those with acral melanoma.

Tumor Burden and Immunotherapy: Impact on Immune Infiltration and Therapeutic Outcomes

Cancer immunotherapy has revolutionized the treatment landscape in medical oncology, but its efficacy has been variable across patients. Biomarkers to predict such differential response to immunotherapy include cytotoxic T lymphocyte infiltration, tumor mutational burden, and microsatellite instability. A growing number of studies also suggest that baseline tumor burden, or tumor size, predicts response to immunotherapy. In this review, we discuss the changes in immune profile and therapeutic responses that occur with increasing tumor size. We also overview therapeutic approaches to reduce tumor burden and favorably modulate the immune microenvironment of larger tumors.

Clinical Proteomics of Metastatic Melanoma Reveals Profiles of Organ Specificity and Treatment Resistance

PURPOSE

Treatment of metastatic melanoma has dramatically improved in recent years, thanks to the development of immunotherapy and BRAF-MEK-targeted therapies. However, these developments revealed marked heterogeneity in patient response, which is yet to be fully understood. In this work, we aimed to associate the proteomic profiles of metastatic melanoma with the patient clinical information, to identify protein correlates with metastatic location and prior treatments.

EXPERIMENTAL DESIGN

We performed mass spectrometry-based proteomic analysis of 185 metastatic melanoma samples and followed with bioinformatics analysis to examine the association of metastatic location, BRAF status, survival, and immunotherapy response with the tumor molecular profiles.

RESULTS

Bioinformatics analysis showed a high degree of functional heterogeneity associated with the site of metastasis. Lung metastases presented higher immune-related proteins, and higher mitochondrial-related processes, which were shown previously to be associated with better immunotherapy response. In agreement, epidemiological analysis of data from the National Cancer Database showed improved response to anti-programmed death 1, mainly in patients with lung metastasis. Focus on lung metastases revealed prognostic and molecular heterogeneity and highlighted potential tissue-specific biomarkers. Analysis of the BRAF mutation status and prior treatments with MAPK inhibitors proposed the molecular basis of the effect on immunotherapy response and suggested coordinated combination of immunotherapy and targeted therapy may increase treatment efficacy.

CONCLUSIONS

Altogether, the proteomic data provided novel molecular determinants of critical clinical features, including the effects of sequential treatments and metastatic locations. These results can be the basis for development of site-specific treatments toward treatment personalization.

Chemotherapy combined with antiangiogenic drugs as salvage therapy in advanced melanoma patients progressing on PD-1 immunotherapy

BACKGROUND

This study aimed to evaluate the effect of salvage therapy with nab-paclitaxel (nab-p) or temozolomide (TMZ) combined with antiangiogenic drugs in programmed death 1 (PD-1) inhibitor-resistant patients with unresectable metastatic melanoma.

METHODS

We conducted a retrospective review of 69 metastatic melanoma patients who received nab-p or TMZ combined with antiangiogenic drugs after developing PD-1 inhibitor resistance and were treated at the Beijing Cancer Hospital between 2016 and 2019. The disease control rate (c-DCR) and progression-free survival (c-PFS) of salvage CA (chemotherapy combined with antiangiogenic drugs) regimens were investigated. Univariate and multivariate analyses were performed to evaluate the clinical pathological factors affecting the outcomes. Then, a nomogram was formulated to predict the probability of 3-month and 6-month c-PFS based on the multivariate analysis results.

RESULTS

The c-DCR was 63.8%, and the median c-PFS was 3.0 months. In the univariate analysis, factors associated with the c-DCR were included the melanoma subtype, baseline platelet-to-lymphocyte ratio (PLR) and best response status to PD-1 inhibitors. Factors influencing c-PFS included age, baseline lactic dehydrogenase, PLR, neutrophil-to-lymphocyte ratio (NLR), PFS duration of anti-PD-1 therapy (p-PFS), and the best response and progression pattern of PD-1 inhibitors. In the multivariate analysis, age <65 years, heterogeneous progression pattern and baseline PLR<200 were significantly associated with improved c-PFS. The concordance index (C-index) of the nomogram was equal to 0.65 (95% CI 0.566-0.734).

CONCLUSIONS

CA regimens demonstrated promising effects in PD-1 inhibitor-resistant patients. The nomogram could be a valuable predictive module for salvage therapy choice in PD-1 inhibitor-resistant patients.

MR-guided stereotactic body radiation therapy for intracardiac and pericardial metastases

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Radiation is not typical in the standard of care for cardiac metastases.

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MR-guided radiation uses real-time imaging and offers better soft tissue contrast.

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Real-time MR-guidance allows for safe high dose radiation to cardiac metastases.

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MR-guided stereotactic radiation can improve symptoms without acute toxicity.

Aims

To assess the safety and efficacy of MR-guided stereotactic body radiation therapy (MRgSBRT) for cardiac metastases.

Materials/methods

This single institution retrospective analysis evaluated our experience with MRgSBRT for cardiac metastases. Response rate was compared between pre-RT and post-RT imaging. Symptomatic changes were also tracked and documented.

Results

Between 4/2019 and 3/2020, five patients with cardiac metastases (4 intracardiac and 1 pericardial) were treated with MRgSBRT. Median age at treatment was 73 years (range 64–80) and two patients had pre-existing cardiac disease. Histologies included melanoma and breast adenocarcinoma. Median lesion diameter was 2 cm (range 1.96–5.8 cm). Three patients were symptomatic, one of whom had pulmonary hypertension and RV enlargement. Another patient had an asymptomatic arrythmia. Median PTV prescribed dose was 40 Gy (range 40–50 Gy) and delivered in five fractions on nonconsecutive days. Median PTV volume was 53.4 cc (range 8.7–116.6 cc) and median coverage was 95% (range 84.1–100%). A uniform 3 mm margin was used for real-time gating, allowing a median 7% (range 5–10%) pixel excursion tolerance. Median follow-up was 4.7 months (range 0.9–12.3). Two patients exhibited stable disease, two had a partial response and one exhibited a complete response. All symptomatic patients experienced some relief. There were no acute adverse events, however, one patient without prior cardiac disease developed atrial fibrillation 6 months after treatment. Two patients died of causes unrelated to cardiac MRgSBRT.

Conclusion

In this largest known series of cardiac metastasis MRgSBRT, real-time image guidance enables safe treatment resulting in good response with improving presenting symptoms without acute adverse events.

Therapy-Induced Modulation of the Tumor Microenvironment: New Opportunities for Cancer Therapies

Advances in immunotherapy have achieved remarkable clinical outcomes in tumors with low curability, but their effects are limited, and increasing evidence has implicated tumoral and non-tumoral components of the tumor microenvironment as critical mediators of cancer progression. At the same time, the clinical successes achieved with minimally invasive and optically-guided surgery and image-guided and ablative radiation strategies have been successfully implemented in clinical care. More effective, localized and safer treatments have fueled strong research interest in radioimmunotherapy, which has shown the potential immunomodulatory effects of ionizing radiation. However, increasingly more observations suggest that immunosuppressive changes, metabolic remodeling, and angiogenic responses in the local tumor microenvironment play a central role in tumor recurrence. In this review, we address challenges to identify responders vs. non-responders to the immune checkpoint blockade, discuss recent developments in combinations of immunotherapy and radiotherapy for clinical evaluation, and consider the clinical impact of immunosuppressive changes in the tumor microenvironment in the context of surgery and radiation. Since the therapy-induced modulation of the tumor microenvironment presents a multiplicity of forms, we propose that overcoming microenvironment related resistance can become clinically relevant and represents a novel strategy to optimize treatment immunogenicity and improve patient outcome.

Impact of anatomic site on antigen-presenting cells in cancer

Checkpoint blockade immunotherapy (CBT) can induce long-term clinical benefits in patients with advanced cancer; however, response rates to CBT vary by cancer type. Cancers of the skin, lung, and kidney are largely responsive to CBT, while cancers of the pancreas, ovary, breast, and metastatic lesions to the liver respond poorly. The impact of tissue-resident immune cells on antitumor immunity is an emerging area of investigation. Recent evidence indicates that antitumor immune responses and efficacy of CBT depend on the tissue site of the tumor lesion. As myeloid cells are predominantly tissue-resident and can shape tumor-reactive T cell responses, it is conceivable that tissue-specific differences in their function underlie the tissue-site-dependent variability in CBT responses. Understanding the roles of tissue-specific myeloid cells in antitumor immunity can open new avenues for treatment design. In this review, we discuss the roles of tissue-specific antigen-presenting cells (APCs) in governing antitumor immune responses, with a particular focus on the contributions of tissue-specific dendritic cells. Using the framework of the Cancer-Immunity Cycle, we examine the contributions of tissue-specific APC in CBT-sensitive and CBT-resistant carcinomas, highlight how these cells can be therapeutically modulated, and identify gaps in knowledge that remain to be addressed.

Anti-PD-1 Immunotherapy and Radiotherapy for Stage IV Intrahepatic Cholangiocarcinoma: A Case Report

Due to the unsatisfactory robustness of current predictive biomarkers in many cases, application of immunotherapy in advanced cancers with limited treatment options, such as stage IV intrahepatic cholangiocarcinoma (ICC), was quite common. Hence, strategies to enhance the therapeutic effect of immunotherapy or to extend the scope of potential beneficial patients were urgently needed. Combination of radiotherapy and anti-programmed death receptor-1 (PD-1) immunotherapy was a promising one, since they were found to have a synergistic anti-tumor effect in animal models and a couple of patients. We here present a 68-years-old male with chemotherapy-intolerable stage IV ICC, whose primary tumor had low PD-L1 expression level, scarce CD8+ cells in tumor microenvironment, high microsatellite instability (MSI), and high tumor mutation burden (TMB). These biomarkers showed a conflicting prediction of the treatment response and clinical benefit of anti-PD-1 immunotherapy. Combination therapy of anti-PD-1 immunotherapy and radiotherapy was adopted as first-line treatment for the patient. After six cycles of immunotherapy, shrinkage of the primary liver tumor and metastatic lymph nodes happened, alongside with new lung metastasis, which indicated a mixed response. Radiotherapy was then administered to both the liver and lung lesions, accompanied with continued immunotherapy. The combined therapy eventually led to a complete response for both the primary tumor and all metastases without treatment-related adverse effects. The patient has survived for 26 months after the combined therapy and remains tumor-free currently. This case demonstrates the high inconsistency between immunotherapy response biomarkers and the synergetic anti-tumor effect of immunotherapy and radiotherapy in ICC.

Transcriptional downregulation of MHC class I and melanoma de- differentiation in resistance to PD-1 inhibition

Transcriptomic signatures designed to predict melanoma patient responses to PD-1 blockade have been reported but rarely validated. We now show that intra-patient heterogeneity of tumor responses to PD-1 inhibition limit the predictive performance of these signatures. We reasoned that resistance mechanisms will reflect the tumor microenvironment, and thus we examined PD-1 inhibitor resistance relative to T-cell activity in 94 melanoma tumors collected at baseline and at time of PD-1 inhibitor progression. Tumors were analyzed using RNA sequencing and flow cytometry, and validated functionally. These analyses confirm that major histocompatibility complex (MHC) class I downregulation is a hallmark of resistance to PD-1 inhibitors and is associated with the MITF^low/AXL^high de-differentiated phenotype and cancer-associated fibroblast signatures. We demonstrate that TGFß drives the treatment resistant phenotype (MITF^low/AXL^high) and contributes to MHC class I downregulation in melanoma. Combinations of anti-PD-1 with drugs that target the TGFß signaling pathway and/or which reverse melanoma de-differentiation may be effective future therapeutic strategies.

A significant proportion of patients develop innate or acquired resistance to immune checkpoint inhibitors. Here, the authors show that resistance to anti-PD-1 blockade is associated with TGF-beta driven major histocompatibility complex I (MHCI) down-regulation and a de-differentiated phenotype in melanoma patients.

Learning from clinical trials of neoadjuvant checkpoint blockade

Neoadjuvant checkpoint inhibition, in which the therapy is administered before surgery, is a promising new approach to managing bulky but resectable melanoma, and is also being explored in other cancers. This strategy has a high pathologic response rate, which correlates with survival outcomes. The fact that biopsies are routinely available provides a unique opportunity for understanding the responses to therapy and carrying out reverse translation in which these data are used to select therapies in the clinic or in trials that are more likely to improve patient outcomes. In this Perspective, we discuss the rationale for neoadjuvant immunotherapy in resectable solid tumors based on preclinical and human translational data, summarize the results of recent clinical trials and ongoing research, and focus on future directions for enhancing reverse translation.

Tissue-specific tumor microenvironments influence responses to immunotherapies

Objectives

Investigation of variable response rates to cancer immunotherapies has exposed the immunosuppressive tumor microenvironment (TME) as a limiting factor of therapeutic efficacy. A determinant of TME composition is the tumor location, and clinical data have revealed associations between certain metastatic sites and reduced responses. Preclinical models to study tissue‐specific TMEs have eliminated genetic heterogeneity, but have investigated models with limited clinical relevance.

Methods

We investigated the TMEs of tumors at clinically relevant sites of metastasis (liver and lungs) and their impact on αPD‐1/αCTLA4 and trimAb (αDR5, α4‐1BB, αCD40) therapy responses in the 67NR mouse breast cancer and Renca mouse kidney cancer models.

Results

Tumors grown in the lungs were resistant to both therapies whereas the same tumor lines growing in the mammary fat pad (MFP), liver or subcutaneously could be completely eradicated, despite greater tumor burden. Assessment of tumor cells and drug delivery in 67NR lung or MFP tumors revealed no differences and prompted investigation into the immune TME. Lung tumors had a more immunosuppressive TME with increased myeloid‐derived suppressor cell infiltration, decreased T cell infiltration and activation, and decreased NK cell activation. Depletion of various immune cell subsets indicated an equivalent role for NK cells and CD8⁺ T cells in lung tumour control. Thus, targeting T cells with αPD‐1/αCTLA4 or trimAb was not sufficient to elicit a robust antitumor response in lung tumors.

Conclusion

Taken together, these data demonstrate that tissue‐specific TMEs influence immunotherapy responses and highlight the importance in defining tissue‐specific response patterns in patients.

Tissue Site and the Cancer Immunity Cycle

Checkpoint blockade immunotherapy (CBT) has revolutionized cancer treatment; however, the cellular and molecular factors that govern responsiveness to immunotherapy remain poorly understood. One emerging area of clinical importance is differential responsiveness to CBT across different tissue sites of tumor growth. Each tissue site in the body can contain unique tissue-resident immune cells from both the lymphoid and the myeloid compartment and differences in tissue-specific immune cell composition might predispose tumors in certain tissue sites to be more or less responsive to immunotherapy. Understanding the interplay between tissue-resident and systemic immune responses against tumors will help to determine how to better therapeutically target the immune system to fight cancer. This review summarizes clinical and preclinical investigations of tissue-specific antitumor immune responses and how they influence the tumor immune microenvironment and the efficacy of immunotherapy.

Tumor mutation burden and circulating tumor DNA in combined CTLA-4 and PD-1 antibody therapy in metastatic melanoma - results of a prospective biomarker study

Background

Metastasized or unresectable melanoma has been the first malignant tumor to be successfully treated with checkpoint inhibitors. Nevertheless, about 40–50% of the patients do not respond to these treatments and severe side effects are observed in up to 60%. Therefore, there is a high need to identify reliable biomarkers predicting response.

Tumor Mutation Burden (TMB) is a debated predictor for response to checkpoint inhibitors and early measurement of ctDNA can help to detect treatment failure to immunotherapy in selected melanoma patients. However, it has not yet been clarified how TMB and ctDNA can be used to estimate response to combined CTLA-4 and PD-1 antibody therapy in metastatic melanoma.

Patients and methods

In this prospective biomarker study, we included 35 melanoma patients with ipilimumab (anti-CTLA-4) and nivolumab (anti-PD-1) therapy. In all patients, a tumor panel of 710 tumor-associated genes was applied (tumor vs. reference tissue comparison), followed by repetitive liquid biopsies. Cell-free DNA was extracted and at least one driver mutation was monitored. Treatment response was evaluated after about three months of therapy.

Results

TMB was significantly higher in responders than in nonresponders and TMB > 23.1 Mut/Mb (TMB-high) was associated with a survival benefit compared to TMB ≤ 23.1 Mut/Mb (TMB-low or TMB-intermediate). Furthermore, a > 50% decrease of cell-free DNA concentration or undetectable circulating tumor DNA (ctDNA), measured by tumor-specific variant copies/ml of plasma at first follow-up three weeks after treatment initiation were significantly associated with response to combined immunotherapy and improved overall survival, respectively. It is noticeable that no patient with TMB ≤ 23.1 Mut/Mb and detectable or increasing ctDNA at first follow-up responded to immunotherapy.

Conclusion

High TMB, > 50% decrease of cell-free DNA concentration, and undetectable ctDNA at first follow-up seem to be associated with response and overall survival under combined immunotherapy. The evaluation of ctDNA and cell-free DNA three weeks after treatment initiation may be suitable for early assessment of efficacy of immunotherapy.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0659-0) contains supplementary material, which is available to authorized users.

Clinical Correlates of Response to Anti-PD-1-based Therapy in Patients With Metastatic Melanoma

Anti-PD-1 agents, alone or in combination with ipilimumab, produce durable responses in some melanoma patients. Tumor features that correlate with response are not well defined. We collected clinical data from metastatic melanoma patients treated at 2 centers who received anti-PD-1 (n=303) or anti-PD-1+ipilimumab (n=57). We correlated number of metastases, diameter of largest tumor (tumor bulk), and organ involvement with response rate (RR), progression-free survival (PFS), and overall survival (OS). Patients with diameter of largest tumor ≤2 cm had a 53% RR, whereas those with largest tumor >2 cm had a 38% RR (P=0.009). Those with liver metastases had lower RR (25% vs. 43%; P=0.002). RR to anti-PD-1 was greater in patients with ≤10 metastases compared with those with >10 (39% vs. 27%; P=0.027). In multivariable analyses, size of the largest tumor was independently associated with PFS (P=0.0005), OS (P<0.0001), and RR (P=0.02), whereas AJCC stage, lactate dehydrogenase, liver metastases, ECOG performance status, number of metastases, and prior therapies were not. In patients treated with anti-PD-1+ipilimumab, however, tumor bulk was not associated with outcomes, although number of metastases was associated with PFS (P=0.035) and RR (P=0.009) but not OS. Pathologic analysis did not reveal differences in T-cell infiltration in bulky versus small tumors. Tumor bulk, defined by diameter of largest tumor, was strongly and independently associated with clinical outcomes in anti-PD-1 but not in anti-PD-1+ipilimumab. In conjunction with molecular biomarkers, clinical predictors may help guide selection of immunotherapy agents.

Interactions in the (Pre)metastatic Niche Support Metastasis Formation

Metastasis formation is the leading cause of death in cancer patients. Thus, understanding and targeting this process is an unmet need. Crucial steps during the establishment of metastases include the (pre)metastatic niche formation. This process relies on the interaction of the primary tumor with the environment of distant organs (premetastatic niche) and the interaction of cancer cells with their environment when arriving in a distant organ (metastatic niche). Here, we summarize the current knowledge on the interactions in the tumor environment that result in (pre)metastatic niche formation, specifically in the context of tumor secreted factors, extracellular matrix, immune as well as stromal cells, and nutrient availability. We further highlight strategies to disrupt these interactions as therapeutic interventions against metastases.

Targeting Tumor Metabolism: A New Challenge to Improve Immunotherapy

Currently, a marked number of clinical trials on cancer treatment have revealed the success of immunomodulatory therapies based on immune checkpoint inhibitors that activate tumor-specific T cells. However, the therapeutic efficacy of cancer immunotherapies is only restricted to a small fraction of patients. A deeper understanding of key mechanisms generating an immunosuppressive tumor microenvironment (TME) remains a major challenge for more effective antitumor immunity. There is a growing evidence that the TME supports inappropriate metabolic reprogramming that dampens T cell function, and therefore impacts the antitumor immune response and tumor progression. Notably, the immunosuppressive TME is characterized by a lack of crucial carbon sources critical for T cell function and increased inhibitory signals. Here, we summarize the basics of intrinsic and extrinsic metabolic remodeling and metabolic checkpoints underlying the competition between cancer and infiltrating immune cells for nutrients and metabolites. Intriguingly, the upregulation of tumor programmed death-L1 and cytotoxic T lymphocyte-associated antigen 4 alters the metabolic programme of T cells and drives their exhaustion. In this context, targeting both tumor and T cell metabolism can beneficially enhance or temper immunity in an inhospitable microenvironment and markedly improve the success of immunotherapies.