Longitudinal gut microbiome changes in immune checkpoint blockade-treated advanced melanoma.

Multiple clinical trials targeting the gut microbiome are being conducted to optimize treatment outcomes for immune checkpoint blockade (ICB). To improve the success of these interventions, understanding gut microbiome changes during ICB is urgently needed. Here through longitudinal microbiome profiling of 175 patients treated with ICB for advanced melanoma, we show that several microbial species-level genome bins (SGBs) and pathways exhibit distinct patterns from baseline in patients achieving progression-free survival (PFS) of 12 months or longer (PFS ≥12) versus patients with PFS shorter than 12 months (PFS <12). Out of 99 SGBs that could discriminate between these two groups, 20 were differentially abundant only at baseline, while 42 were differentially abundant only after treatment initiation. We identify five and four SGBs that had consistently higher abundances in patients with PFS ≥12 and <12 months, respectively. Constructing a log ratio of these SGBs, we find an association with overall survival. Finally, we find different microbial dynamics in different clinical contexts including the type of ICB regimen, development of immune-related adverse events and concomitant medication use. Insights into the longitudinal dynamics of the gut microbiome in association with host factors and treatment regimens will be critical for guiding rational microbiome-targeted therapies aimed at enhancing ICB efficacy.

A Survival Tree of Advanced Melanoma Patients with Brain Metastases Treated with Immune Checkpoint Inhibitors.

The efficacy of immune checkpoint inhibitors (ICIs) in patients with advanced melanoma that develop brain metastases (BM) remains unpredictable. In this study, we aimed to identify prognostic factors in patients with melanoma BM who are treated with ICIs. Data from advanced melanoma patients with BM treated with ICIs in any line between 2013 and 2020 were obtained from the Dutch Melanoma Treatment Registry. Patients were included from the time of the treatment of BM with ICIs. Survival tree analysis was performed with clinicopathological parameters as potential classifiers and overall survival (OS) as the response variable. In total, 1278 patients were included. Most patients were treated with ipilimumab-nivolumab combination therapy (45%). The survival tree analysis resulted in 31 subgroups. The median OS ranged from 2.7 months to 35.7 months. The strongest clinical parameter associated with survival in advanced melanoma patients with BM was the serum lactate dehydrogenase (LDH) level. Patients with elevated LDH levels and symptomatic BM had the worst prognosis. The clinicopathological classifiers identified in this study can contribute to optimizing clinical studies and can aid doctors in giving an indication of the patients' survival based on their baseline and disease characteristics.

Value of screening and follow-up brain MRI scans in patients with metastatic melanoma.

BACKGROUND: Novel treatments make long-term survival possible for subsets of patients with melanoma brain metastases. Brain magnetic resonance imaging (MRI) may aid in early detection of brain metastases and inform treatment decisions. This study aimed to determine the impact of screening MRI scans in patients with metastatic melanoma and follow-up MRI scans in patients with melanoma brain metastases. METHODS: This retrospective cohort study included patients diagnosed with metastatic melanoma or melanoma brain metastases between June 2015 and January 2018. The impact of screening MRI scans was evaluated in the first 2 years after metastatic melanoma diagnosis. The impact of follow-up MRI scans was examined in the first year after brain metastases diagnosis. The number of MRI scans, scan indications, scan outcomes, and changes in treatment strategy were analyzed. RESULTS: In total, 116 patients had no brain metastases at the time of the metastatic melanoma diagnosis. Twenty-eight of these patients (24%) were subsequently diagnosed with brain metastases. Screening MRI scans detected the brain metastases in 11/28 patients (39%), of which 8 were asymptomatic at diagnosis. In the 96 patients with melanoma brain metastases, treatment strategy changed after 75/168 follow-up MRI scans (45%). In patients treated with immune checkpoint inhibitors, the number of treatment changes after follow-up MRI scans was lower when patients had been treated longer. CONCLUSION(S): Screening MRI scans aid in early detection of melanoma brain metastases, and follow-up MRI scans inform treatment strategy. In patients with brain metastases responding to immune checkpoint inhibitors, treatment changes were less frequently observed after follow-up MRI scans. These results can inform the development of brain imaging protocols for patients with immune checkpoint inhibitor sensitive tumors.

Interleukin-2 PET imaging in patients with metastatic melanoma before and during immune checkpoint inhibitor therapy.

PURPOSE: Immune checkpoint inhibitors can induce a T cell-mediated anti-tumor immune response in patients with melanoma. Visualizing T cell activity using positron emission tomography (PET) might allow early insight into treatment efficacy. Activated tumor-infiltrating T cells express the high-affinity interleukin-2 receptor (IL-2R). Therefore, we performed a pilot study, using fluorine-18-labeled IL-2 ([18F]FB-IL2 PET), to evaluate whether a treatment-induced immune response can be detected. METHODS: Patients with metastatic melanoma received ~ 200 MBq [18F]FB-IL2 intravenously, followed by a PET/CT scan before and during immune checkpoint inhibitor therapy. [18F]FB-IL2 uptake was measured as standardized uptake value in healthy tissues (SUVmean) and tumor lesions (SUVmax). Response to therapy was assessed using RECIST v1.1. Archival tumor tissues were used for immunohistochemical analyses of T cell infiltration. RESULTS: Baseline [18F]FB-IL2 PET scans were performed in 13 patients. SUVmean at baseline was highest in the kidneys (14.2, IQR: 11.6-18.0) and liver (10.6, IQR: 8.6-13.4). In lymphoid tissues, uptake was highest in spleen (10.9, IQR: 8.8-12.4) and bone marrow (2.5, IQR: 2.1-3.0). SUVmax in tumor lesions (n = 41) at baseline was 1.9 (IQR: 1.7-2.3). In 11 patients, serial imaging was performed, three at week 6, seven at week 2, and one at week 4. Median [18F]FB-IL2 tumor uptake decreased from 1.8 (IQR: 1.7-2.1) at baseline to 1.7 (IQR: 1.4-2.1) during treatment (p = 0.043). Changes in [18F]FB-IL2 tumor uptake did not correlate with response. IL-2R expression in four archival tumor tissues was low and did not correlate with baseline [18F]FB-IL2 uptake. No [18F]FB-IL2-related side effects occurred. CONCLUSION: PET imaging of the IL-2R, using [18F]FB-IL2, is safe and feasible. In this small patient group, serial [18F]FB-IL2-PET imaging did not detect a treatment-related immune response. TRIAL REGISTRATION: Clinicaltrials.gov : NCT02922283; EudraCT: 2014-003387.20.

Clinical utility of circulating tumor DNA as a response and follow-up marker in cancer therapy.

Response evaluation for cancer treatment consists primarily of clinical and radiological assessments. In addition, a limited number of serum biomarkers that assess treatment response are available for a small subset of malignancies. Through recent technological innovations, new methods for measuring tumor burden and treatment response are becoming available. By utilization of highly sensitive techniques, tumor-specific mutations in circulating DNA can be detected and circulating tumor DNA (ctDNA) can be quantified. These so-called liquid biopsies provide both molecular information about the genomic composition of the tumor and opportunities to evaluate tumor response during therapy. Quantification of tumor-specific mutations in plasma correlates well with tumor burden. Moreover, with liquid biopsies, it is also possible to detect mutations causing secondary resistance during treatment. This review focuses on the clinical utility of ctDNA as a response and follow-up marker in patients with non-small cell lung cancer, melanoma, colorectal cancer, and breast cancer. Relevant studies were retrieved from a literature search using PubMed database. An overview of the available literature is provided and the relevance of ctDNA as a response marker in anti-cancer therapy for clinical practice is discussed. We conclude that the use of plasma-derived ctDNA is a promising tool for treatment decision-making based on predictive testing, detection of resistance mechanisms, and monitoring tumor response. Necessary steps for translation to daily practice and future perspectives are discussed.

Gut microbial species and metabolic pathways associated with response to treatment with immune checkpoint inhibitors in metastatic melanoma.

In patients with metastatic cancer, gut microbiome composition differs between responder and non-responders to immune checkpoint inhibitors. However, there is little consensus on the microbiome taxa associated with response or lack of response. Additionally, recognized confounders of gut microbiome composition have generally not been taken into account. In this study, metagenomic shotgun sequencing was performed on freshly frozen pre-treatment stool samples from 25 patients (12 responders and 13 non-responders) with unresectable metastatic melanoma treated with immune checkpoint inhibitors. We observed no significant differences in alpha-diversity and bacterial prevalence between responders and non-responders (P > 0.05). In a zero-inflated multivariate analysis, correcting for important confounders such as age, BMI and use of antibiotics, 68 taxa showed differential abundance between responders and non-responders (false-discovery rate < 0.05). Cox-regression analysis showed longer overall survival for carriers of Streptococcus parasanguinis [hazard ratio (HR): 6.9] and longer progression-free survival for carriers of Bacteroides massiliensis (HR: 3.79). In contrast, carriership of Peptostreptococcaceae (unclassified species) was associated with shorter overall survival (HR 0.18) and progression-free survival (HR 0.11). Finally, 17 microbial pathways differentially abundant between responder and non-responders were observed. These results underline the association between gut microbiome composition and response to immune checkpoint inhibitor therapy in a cohort of patients with cutaneous melanoma.

Association Between Pembrolizumab-related Adverse Events and Treatment Outcome in Advanced Melanoma: Results From the Dutch Expanded Access Program.

Toxicity of immune checkpoint inhibitors such as ipilimumab and nivolumab is likely associated with clinical efficacy. In this study, we aim to evaluate this association for pembrolizumab. To this end, data of 147 patients included in the Dutch cohort of the Pembrolizumab Expanded Access Program were collected. All data were collected prospectively. Patients with adverse events (AEs) at any time during therapy showed a higher chance of achieving disease control compared with patients without AEs (low-grade AEs vs. no AEs: odds ratio=12.8, P=0.0002, high-grade AEs vs. no AEs: odds ratio=38.5, P=0.0001) according to a multivariate logistic regression analysis. In addition, Cox regression analysis showed a lower risk of death (hazard ratio: 0.51, 95% confidence interval: 0.28-0.97) and disease progression (hazard ratio: 0.54, 95% confidence interval: 0.30-0.98) over time for patients with high-grade AEs at any time during therapy compared with patients without AEs during therapy. To correct for time dependency of occurrence of AEs, a pseudolandmark analysis at 6 months of therapy was performed. Although significance was lost (Wald test P>0.05), prolonged survival in 3 patients who stopped therapy within 6 months due to the occurrence of AEs was observed, suggesting the potential treatment benefit despite the premature ending of therapy. The occurrence of high-grade toxicity at any time during treatment was associated with higher objective response rates, progression-free survival, and overall survival. There remains a need to assess the predictive value of early occurring AEs on patient survival.

A large pooled analysis refines gene expression-based molecular subclasses in cutaneous melanoma.

This study aimed to establish the number of expression-based molecular subclasses in cutaneous melanoma, identify their dominant biological pathways and evaluate their clinical relevance. To this end, consensus clustering was performed separately on two independent datasets (n = 405 and n = 473) composed of publicly available cutaneous melanoma expression profiles from previous studies. Four expression-based molecular subclasses were identified and labelled 'Oxidative phosphorylation', 'Oestrogen response/p53-pathway', 'Immune' and 'Cell cycle', based on their dominantly expressed biological pathways determined by gene set enrichment analysis. Multivariate survival analysis revealed shorter overall survival in the 'Oxidative phosphorylation' subclass compared to the other subclasses. This was validated in a third independent dataset (n = 214). Finally, in a pooled cohort of 76 patients treated with anti-PD-1 therapy a trend towards a difference in response rates between subclasses was observed ('Immune' subclass: 65% responders, 'Oxidative Phosphorylation' subclass: 60% responders, other subclasses: <50% responders). These findings support the stratification of cutaneous melanoma in four expression-based molecular subclasses.

89Zr-labeled Bispecific T-cell Engager AMG 211 PET Shows AMG 211 Accumulation in CD3-rich Tissues and Clear, Heterogeneous Tumor Uptake.

PURPOSE: Biodistribution of bispecific antibodies in patients is largely unknown. We therefore performed a feasibility study in 9 patients with advanced gastrointestinal adenocarcinomas to explore AMG 211 biodistribution (also known as MEDI-565), an approximately 55 kDa bispecific T-cell engager (BiTE®) directed against carcinoembryonic antigen (CEA) on tumor cells and cluster of differentiation 3 (CD3) on T-cells. EXPERIMENTAL DESIGN: 89Zr-labeled AMG 211 as tracer was administered alone or with cold AMG 211, for PET imaging before and/or during AMG 211 treatment. RESULTS: Before AMG 211 treatment, the optimal imaging dose was 200-µg 89Zr-AMG 211 + 1,800-µg cold AMG 211. At 3 hours, the highest blood pool standardized uptake value (SUV)mean was 4.0, and tracer serum half-life was 3.3 hours. CD3-mediated uptake was clearly observed in CD3-rich lymphoid tissues including spleen and bone marrow (SUVmean 3.2 and 1.8, respectively), and the SUVmean decreased more slowly than in other healthy tissues. 89Zr-AMG 211 remained intact in plasma and was excreted predominantly via the kidneys in degraded forms. Of 43 visible tumor lesions, 37 were PET quantifiable, with a SUVmax of 4.0 [interquartile range (IQR) 2.7-4.4] at 3 hours using the optimal imaging dose. The tracer uptake differed between tumor lesions 5-fold within and 9-fold between patients. During AMG 211 treatment, tracer was present in the blood pool, whereas tumor lesions were not visualized, possibly reflecting target saturation. CONCLUSIONS: This first-in-human study shows high, specific 89Zr-AMG 211 accumulation in CD3-rich lymphoid tissues, as well as a clear, inter- and intraindividual heterogeneous tumor uptake.