Imaging for assessment of cancer treatment response to immune checkpoint inhibitors can be complementary in identifying hypophysitis.

Introduction: Hypophysitis is reported in 8.5%-14% of patients receiving combination immune checkpoint inhibition (cICI) but can be a diagnostic challenge. This study aimed to assess the role of routine diagnostic imaging performed during therapeutic monitoring of combination anti-CTLA-4/anti-PD-1 treatment in the identification of hypophysitis and the relationship of imaging findings to clinical diagnostic criteria. Methods: This retrospective cohort study identified patients treated with cICI between January 2016 and January 2019 at a quaternary melanoma service. Medical records were reviewed to identify patients with a documented diagnosis of hypophysitis based on clinical criteria. Available structural brain imaging with magnetic resonance imaging (MRI) or computed tomography (CT) of the brain and 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography with computed tomography (FDG-PET/CT) were assessed retrospectively. The main radiological outcome measures were a relative change in pituitary size or FDG uptake temporally attributed to cICI. Results: There were 162 patients (median age 60 years, 30% female) included. A total of 100 and 134 had serial CT/MRI of the brain and FDG-PET/CT, respectively. There were 31 patients who had a documented diagnosis of hypophysitis and an additional 20 who had isolated pituitary imaging findings. The pituitary gland enlargement was mild, and the largest absolute gland size was 13 mm, with a relative increase of 7 mm from baseline. There were no cases of optic chiasm compression. Pituitary enlargement and increased FDG uptake were universally transient. High-dose glucocorticoid treatment for concurrent irAEs prevented assessment of the pituitary-adrenal axis in 90% of patients with isolated imaging findings. Conclusion: Careful review of changes in pituitary characteristics on imaging performed for assessment of therapeutic response to iICI may lead to increased identification and more prompt management of cICI-induced hypophysitis.

FDG PET/CT Prognostic Markers in Patients with Advanced Melanoma Treated with Ipilimumab and Nivolumab.

Background Despite improved response to combined ipilimumab and nivolumab (hereafter, IpiNivo) treatment for advanced melanoma, many patients exhibit primary or acquired resistance. This, combined with high risk of immune-related adverse events, makes identifying markers predictive of outcomes desirable. Purpose To investigate the prognostic value of fluorine 18 (18F) fluorodeoxyglucose (FDG) PET/CT parameters at baseline and as part of response monitoring in patients with advanced melanoma undergoing IpiNivo treatment. Materials and Methods This was a single-center retrospective study of adult patients with melanoma who received IpiNivo. Baseline FDG PET/CT parameters that included metabolic tumor volume (MTV), tumor stage, mutation status, Eastern Cooperative Oncology Group performance score, lactate dehydrogenase level, and treatment line were correlated with overall survival in univariable and multivariable Cox regression analyses. Treatment response as determined with FDG PET/CT was correlated with overall survival. Results In total, 122 patients (median age, 61 years [IQR, 51-69 years]; 89 men) were included; 78% (95 of 122) had an Eastern Cooperative Oncology Group score of 0, 52% (45 of 86) had an elevated lactate dehydrogenase level, 39% (48 of 122) had a metastatic stage of M1c and 45% (55 of 122) M1d, 45% (55 of 122) had BRAF V600E/K mutation, and the median MTV was 42 mL. Patients with a higher than median MTV at baseline FDG PET/CT had a lower 12-month survival rate compared with those with a lower than median MTV (43% [95% CI: 32, 58] vs 66% [95% CI: 55, 79], P < .001). In multivariable analysis, higher versus lower than median MTV, Eastern Cooperative Oncology Group performance scores of 1-2 versus 0, and subsequent versus first-line IpiNivo treatment were independently associated with overall survival (hazard ratio [HR]: 1.68 [95% CI: 1.02, 2.78], P = .04; 3.1 [95% CI: 1.8, 5.4], P < .001; and 11.2 [95% CI: 3.4, 37.1], P = .002, respectively). The 12-month overall survival rate was lower in patients with progressive disease than in those without progression (35% [95% CI: 24, 51] vs 90% [95% CI: 83, 99]; HR, 7.3 [95% CI: 3.9, 13.3]; P < .001). Conclusion Baseline fluorine 18 fluorodeoxyglucose PET/CT metabolic tumor volume was an independent prognostic marker in patients with advanced melanoma who received ipilimumab and nivolumab treatment. © RSNA, 2023 Supplemental material is available for this article.

Durability of response to immune checkpoint inhibitors in metastatic Merkel cell carcinoma after treatment cessation.

BACKGROUND: Metastatic Merkel cell carcinoma (mMCC) is highly responsive to immune checkpoint inhibitors (ICIs); however, durability of response after treatment cessation and response to retreatment in the setting of progression is unknown. METHODS: Patients (pts) having mMCC from 10 centres who discontinued ICI treatment for a reason other than progression were studied. RESULTS: Forty patients were included. Median time on treatment was 13.5 months (range 1-35). Thirty-one patients (77.5%) stopped treatment electively while 9 patients (22.5%) stopped due to treatment-related toxicity. After median of 12.3 months from discontinuation, 14 pts (35%) have progressed (PD). Disease progression rate following ICI discontinuation was 26% (8 of 31) in patients who discontinued in complete response (CR), 57% (4 of 7) in patients in partial response and 100% (2 of 2) in those with stable disease. Median progression-free survival (PFS) after treatment cessation was 21 months (95% confidence interval [CI], 18- not reached [NR]), with a third of patients progressing during their first year off treatment. PFS was longer for patients who discontinued ICI electively (median PFS 29 months; 95% CI, 21-NR) compared to those who stopped due to toxicity (median PFS 11 months; 95% CI, 10-NR). ICI was restarted in 8 of 14 pts (57%) with PD, with response rate of 75% (4 CR, 2 partial response, 1 stable disease, 1 PD). CONCLUSION: ICI responses in mMCC do not appear durable off treatment, including in patients who achieve a CR, though response to retreatment is promising. Extended duration of treatment needs to be investigated to optimise long-term outcomes.

Tissue-resident memory T cells from a metastatic vaginal melanoma patient are tumor-responsive T cells and increase after anti-PD-1 treatment.

BACKGROUND: Vaginal melanoma (VM) is a rare cancer and has a poor response to immune checkpoint blockade (ICB). CD8+Tissue Resident Memory (TRM) T cells proliferate in response to ICB and correlate with longer survival in metastatic cutaneous melanoma. However, their capacity to respond to VM and their neoantigens is not known. METHODS: Using longitudinal samples, we explored the evolution of VM mutations by whole-exome sequencing and RNAseq, we also defined the immune context using multiplex immunohistochemistry and nanostring pan cancer immune profile. Then using fresh single cell suspensions of the metastatic samples, we explored VM T cells via mass cytometry and single cell RNAseq and T cell receptor sequencing (TCRseq). Finally, we investigated TRM, pre-TRM and exhausted T cell function against melanoma neo-antigens and melanoma differentiation antigens in vitro. RESULTS: Primary VM was non-inflamed and devoid of CD8+ TRM cells. In contrast, both metastases showed proliferating CD8+ TRM were clustered at the tumor margin, with increased numbers in the second ICB-refractory metastasis. The first metastasis showed dense infiltration of CD8+ T cells, the second showed immune exclusion with loss of melanoma cell Major histocompatibility complex (MHC)-I expression associated with downregulation of antigen presentation pathway gene expression. CD8+ TRM from both metastases responded to autologous melanoma cells more robustly than all other CD8+ T cell subsets. In addition, CD8+ TRM shared TCR clones across metastases, suggesting a response to common antigens, which was supported by recognition of the same neoantigen by expanded tumor infiltrating lymphocytes. CONCLUSIONS: In this study, we identified TRM clusters in VM metastases from a patient, but not primary disease. We showed TRM location at the tumor margin, and their superior functional response to autologous tumor cells, predicted neoantigens and melanoma differentiation antigens. These CD8+ TRM exhibited the highest tumor-responsive potential and shared their TCR with tumor-infiltrating effector memory T cells. This suggests VM metastases from this patient retain strong antitumor T cell functional responses; however, this response is suppressed in vivo. The loss of VG MHC-I expression is a common immune escape mechanism which was not addressed by anti-PD-1 monotherapy; rather an additional targeted approach to upregulate MHC-I expression is required.

Grade 4 Neutropenia Secondary to Immune Checkpoint Inhibition - A Descriptive Observational Retrospective Multicenter Analysis.

INTRODUCTION: Immune checkpoint inhibitors (ICI) are increasingly being used to treat numerous cancer types. Together with improved recognition of toxicities, this has led to more frequent identification of rare immune-related adverse events (irAE), for which specific treatment strategies are needed. Neutropenia is a rare hematological irAE that has a potential for a high mortality rate because of its associated risk of sepsis. Prompt recognition and timely treatment of this life-threatening irAE are therefore critical to the outcome of patients with immune-related neutropenia. METHODS: This multicenter international retrospective study was conducted at 17 melanoma centers to evaluate the clinical characteristics, diagnostics, treatment, and outcomes of melanoma patients with grade 4 neutropenia (<500 neutrophils/µl blood) treated with ICI between 2014 and 2020. Some of these patients received metamizole in addition to ICI (ICI+/met+). Bone marrow biopsies (BMB) of these patients were compared to BMB from non-ICI treated patients with metamizole-induced grade 4 neutropenia (ICI-/met+). RESULTS: In total, 10 patients (median age at neutropenia onset: 66 years; seven men) with neutropenia were identified, equating to an incidence of 0.14%. Median onset of neutropenia was 6.4 weeks after starting ICI (range 1.4-49.1 weeks). Six patients showed inflammatory symptoms, including fever (n=3), erysipelas (n=1), pharyngeal abscess (n=1), and mucositis (n=1). Neutropenia was diagnosed in all patients by a differential blood count and additionally performed procedures including BMB (n=5). Nine of 10 patients received granulocyte colony-stimulating factors (G-CSF) to treat their grade 4 neutropenia. Four patients received systemic steroids (including two in combination with G-CSF, and one in combination with G-CSF and additional ciclosporin A). Four patients were treated with one or more antibiotic treatment lines, two with antimycotic treatment, and one with additional antiviral therapy. Five patients received metamizole concomitantly with ICI. One fatal outcome was reported. BMB indicated a numerically lower CD4+ to CD8+ T cells ratio in patients with irNeutropenia than in those with metamizole-induced neutropenia. CONCLUSION: Grade 4 neutropenia is a rare but potentially life-threatening side effect of ICI treatment. Most cases were sufficiently managed using G-CSF; however, adequate empiric antibiotic, antiviral, and antimycotic treatments should be administered if neutropenic infections are suspected. Immunosuppression using corticosteroids may be considered after other causes of neutropenia have been excluded.

Melanoma brain metastases that progress on BRAF-MEK inhibitors demonstrate resistance to ipilimumab-nivolumab that is associated with the Innate PD-1 Resistance Signature (IPRES).

BACKGROUND: Melanoma brain metastases (MBMs) are a challenging clinical problem with high morbidity and mortality. Although first-line dabrafenib-trametinib and ipilimumab-nivolumab have similar intracranial response rates (50%-55%), central nervous system (CNS) resistance to BRAF-MEK inhibitors (BRAF-MEKi) usually occurs around 6 months, and durable responses are only seen with combination immunotherapy. We sought to investigate the utility of ipilimumab-nivolumab after MBM progression on BRAF-MEKi and identify mechanisms of resistance. METHODS: Patients who received first-line ipilimumab-nivolumab for MBMs or second/third line ipilimumab-nivolumab for intracranial metastases with BRAFV600 mutations with prior progression on BRAF-MEKi and MRI brain staging from March 1, 2015 to June 30, 2018 were included. Modified intracranial RECIST was used to assess response. Formalin-fixed paraffin-embedded samples of BRAFV600 mutant MBMs that were naïve to systemic treatment (n=18) or excised after progression on BRAF-MEKi (n=14) underwent whole transcriptome sequencing. Comparative analyses of MBMs naïve to systemic treatment versus BRAF-MEKi progression were performed. RESULTS: Twenty-five and 30 patients who received first and second/third line ipilimumab-nivolumab, were included respectively. Median sum of MBM diameters was 13 and 20.5 mm for the first and second/third line ipilimumab-nivolumab groups, respectively. Intracranial response rate was 75.0% (12/16), and median progression-free survival (PFS) was 41.6 months for first-line ipilimumab-nivolumab. Efficacy of second/third line ipilimumab-nivolumab after BRAF-MEKi progression was poor with an intracranial response rate of 4.8% (1/21) and median PFS of 1.3 months. Given the poor activity of ipilimumab-nivolumab after BRAF-MEKi MBM progression, we performed whole transcriptome sequencing to identify mechanisms of drug resistance. We identified a set of 178 differentially expressed genes (DEGs) between naïve and MBMs with progression on BRAF-MEKi treatment (p value <0.05, false discovery rate (FDR) <0.1). No distinct pathways were identified from gene set enrichment analyses using Kyoto Encyclopedia of Genes and Genomes, Gene Ontogeny or Hallmark libraries; however, enrichment of DEG from the Innate Anti-PD1 Resistance Signature (IPRES) was identified (p value=0.007, FDR=0.03). CONCLUSIONS: Second-line ipilimumab-nivolumab for MBMs after BRAF-MEKi progression has poor activity. MBMs that are resistant to BRAF-MEKi that also conferred resistance to second-line ipilimumab-nivolumab showed enrichment of the IPRES gene signature.

Combination anti-PD1 and ipilimumab therapy in patients with advanced melanoma and pre-existing autoimmune disorders.

BACKGROUND: Clinical trials of immunotherapy have excluded patients with pre-existing autoimmune disease. While the safety and efficacy of single agent ipilimumab and anti-PD1 antibodies in patients with autoimmune disease has been examined in retrospective studies, no data are available for combination therapy which has significantly higher toxicity risk. We sought to establish the safety and efficacy of combination immunotherapy for patients with advanced melanoma and pre-existing autoimmune diseases. METHODS: We performed a retrospective study of patients with advanced melanoma and pre-existing autoimmune disease who received combination ipilimumab and anti-PD1 at 10 international centers from March 2015 to February 2020. Data regarding the autoimmune disease, treatment, toxicity and outcomes were examined in patients. RESULTS: Of the 55 patients who received ipilimumab and anti-PD1, the median age was 63 years (range 23-83). Forty-six were treated with ipilimumab and nivolumab and nine with ipilimumab and pembrolizumab.Eighteen patients (33%) had a flare of their autoimmune disease including 4 of 7 with rheumatoid arthritis, 3 of 6 with psoriasis, 5 of 10 with inflammatory bowel disease, 3 of 19 with thyroiditis, 1 of 1 with Sjogren's syndrome, 1 of 1 with polymyalgia and 1 of 1 with Behcet's syndrome and psoriasis. Eight (44%) patients ceased combination therapy due to flare. Thirty-seven patients (67%) had an unrelated immune-related adverse event (irAE), and 20 (36%) ceased combination immunotherapy due to irAEs. There were no treatment-related deaths. Patients on immunosuppression (OR 4.59; p=0.03) had a higher risk of flare.The overall response rate was 55%, with 77% of responses ongoing. Median progression free survival and overall survival were 10 and 24 months, respectively. Patients on baseline immunosuppression had an overall survival of 11 months (95% CI 3.42 to 18.58) compared with 31 months without (95% CI 20.89 to 41.11, p=0.005). CONCLUSIONS: In patients with pre-existing autoimmune disease, not on immunosuppression and advanced melanoma, combination ipilimumab and anti-PD1 has similar efficacy compared with previously reported trials. There is a risk of flare of pre-existing autoimmune disorders, particularly in patients with inflammatory bowel disease and rheumatologic conditions, and patients on baseline immunosuppression.

The role of local therapy in the treatment of solitary melanoma progression on immune checkpoint inhibition: A multicentre retrospective analysis.

INTRODUCTION: In patients with metastatic melanoma, progression of a single tumour lesion (solitary progression) after response to immune checkpoint inhibition (ICI) is increasingly treated with local therapy. We evaluated the role of local therapy for solitary progression in melanoma. PATIENTS AND METHODS: Patients with metastatic melanoma treated with ICI between 2010 and 2019 with solitary progression as first progressive event were included from 17 centres in 9 countries. Follow-up and survival are reported from ICI initiation. RESULTS: We identified 294 patients with solitary progression after stable disease in 15%, partial response in 55% and complete response in 30%. The median follow-up was 43 months; the median time to solitary progression was 13 months, and the median time to subsequent progression after treatment of solitary progression (TTSP) was 33 months. The estimated 3-year overall survival (OS) was 79%; median OS was not reached. Treatment consisted of systemic therapy (18%), local therapy (36%), both combined (42%) or active surveillance (4%). In 44% of patients treated for solitary progression, no subsequent progression occurred. For solitary progression during ICI (n = 143), the median TTSP was 29 months. Both TTSP and OS were similar for local therapy, ICI continuation and both combined. For solitary progression post ICI (n = 151), the median TTSP was 35 months. TTSP was higher for ICI recommencement plus local therapy than local therapy or ICI recommencement alone (p = 0.006), without OS differences. CONCLUSION: Almost half of patients with melanoma treated for solitary progression after initial response to ICI had no subsequent progression. This study suggests that local therapy can benefit patients and is associated with favourable long-term outcomes.

Ipilimumab alone or ipilimumab plus anti-PD-1 therapy in patients with metastatic melanoma resistant to anti-PD-(L)1 monotherapy: a multicentre, retrospective, cohort study.

BACKGROUND: Anti-PD-1 therapy (hereafter referred to as anti-PD-1) induces long-term disease control in approximately 30% of patients with metastatic melanoma; however, two-thirds of patients are resistant and will require further treatment. We aimed to determine the efficacy and safety of ipilimumab plus anti-PD-1 (pembrolizumab or nivolumab) compared with ipilimumab monotherapy in patients who are resistant to anti-PD-(L)1 therapy (hereafter referred to as anti-PD-[L]1). METHODS: This multicentre, retrospective, cohort study, was done at 15 melanoma centres in Australia, Europe, and the USA. We included adult patients (aged ≥18 years) with metastatic melanoma (unresectable stage III and IV), who were resistant to anti-PD-(L)1 (innate or acquired resistance) and who then received either ipilimumab monotherapy or ipilimumab plus anti-PD-1 (pembrolizumab or nivolumab), based on availability of therapies or clinical factors determined by the physician, or both. Tumour response was assessed as per standard of care (CT or PET-CT scans every 3 months). The study endpoints were objective response rate, progression-free survival, overall survival, and safety of ipilimumab compared with ipilimumab plus anti-PD-1. FINDINGS: We included 355 patients with metastatic melanoma, resistant to anti-PD-(L)1 (nivolumab, pembrolizumab, or atezolizumab), who had been treated with ipilimumab monotherapy (n=162 [46%]) or ipilimumab plus anti-PD-1 (n=193 [54%]) between Feb 1, 2011, and Feb 6, 2020. At a median follow-up of 22·1 months (IQR 9·5-30·9), the objective response rate was higher with ipilimumab plus anti-PD-1 (60 [31%] of 193 patients) than with ipilimumab monotherapy (21 [13%] of 162 patients; p<0·0001). Overall survival was longer in the ipilimumab plus anti-PD-1 group (median overall survival 20·4 months [95% CI 12·7-34·8]) than with ipilimumab monotherapy (8·8 months [6·1-11·3]; hazard ratio [HR] 0·50, 95% CI 0·38-0·66; p<0·0001). Progression-free survival was also longer with ipilimumab plus anti-PD-1 (median 3·0 months [95% CI 2·6-3·6]) than with ipilimumab (2·6 months [2·4-2·9]; HR 0·69, 95% CI 0·55-0·87; p=0·0019). Similar proportions of patients reported grade 3-5 adverse events in both groups (59 [31%] of 193 patients in the ipilimumab plus anti-PD-1 group vs 54 [33%] of 162 patients in the ipilimumab group). The most common grade 3-5 adverse events were diarrhoea or colitis (23 [12%] of 193 patients in the ipilimumab plus anti-PD-1 group vs 33 [20%] of 162 patients in the ipilimumab group) and increased alanine aminotransferase or aspartate aminotransferase (24 [12%] vs 15 [9%]). One death occurred with ipilimumab 26 days after the last treatment: a colon perforation due to immune-related pancolitis. INTERPRETATION: In patients who are resistant to anti-PD-(L)1, ipilimumab plus anti-PD-1 seemed to yield higher efficacy than ipilimumab with a higher objective response rate, longer progression-free, and longer overall survival, with a similar rate of grade 3-5 toxicity. Ipilimumab plus anti-PD-1 should be favoured over ipilimumab alone as a second-line immunotherapy for these patients with advanced melanoma. FUNDING: None.

γδ T Cells in Merkel Cell Carcinomas Have a Proinflammatory Profile Prognostic of Patient Survival.

Merkel cell carcinomas (MCC) are immunogenic skin cancers associated with viral infection or UV mutagenesis. To study T-cell infiltrates in MCC, we analyzed 58 MCC lesions from 39 patients using multiplex-IHC/immunofluorescence (m-IHC/IF). CD4+ or CD8+ T cells comprised the majority of infiltrating T lymphocytes in most tumors. However, almost half of the tumors harbored prominent CD4/CD8 double-negative (DN) T-cell infiltrates (>20% DN T cells), and in 12% of cases, DN T cells represented the majority of T cells. Flow cytometric analysis of single-cell suspensions from fresh tumors identified DN T cells as predominantly Vδ2- γδ T cells. In the context of γδ T-cell inflammation, these cells expressed PD-1 and LAG3, which is consistent with a suppressed or exhausted phenotype, and CD103, which indicates tissue residency. Furthermore, single-cell RNA sequencing (scRNA-seq) identified a transcriptional profile of γδ T cells suggestive of proinflammatory potential. T-cell receptor (TCR) analysis confirmed clonal expansion of Vδ1 and Vδ3 clonotypes, and functional studies using cloned γδ TCRs demonstrated restriction of these for CD1c and MR1 antigen-presenting molecules. On the basis of a 13-gene γδ T-cell signature derived from scRNA-seq analysis, gene-set enrichment on bulk RNA-seq data showed a positive correlation between enrichment scores and DN T-cell infiltrates. An improved disease-specific survival was evident for patients with high enrichment scores, and complete responses to anti-PD-1/PD-L1 treatment were observed in three of four cases with high enrichment scores. Thus, γδ T-cell infiltration may serve as a prognostic biomarker and should be explored for therapeutic interventions.See related Spotlight on p. 600.

Hematological immune related adverse events after treatment with immune checkpoint inhibitors.

INTRODUCTION: With the increasing use of checkpoint inhibitors, rare immune-related adverse events (irAE) are being identified. Haematological irAE (hem-irAE) are difficult to treat and have shown high mortality rates. In order to improve side-effect management for these potentially life-threatening events, we analysed frequency, severity and outcomes. PATIENTS AND METHODS: Patients who developed hem-irAE while being treated with immune checkpoint inhibitors (ICI) therapy were retrospectively identified from 18 international cancer centres. RESULTS: In total, more than 7626 patients treated with ICI were screened, and 50 patients with hem-irAE identified. The calculated incidence amounts to 0.6% and median onset was 6 weeks after the ICI initiation (range 1-128 weeks). Thrombocytopenia and leucopaenia were the most frequent hem-irAE with 34% (17/50) and 34% (17/50), respectively, followed by anaemia 28% (14/50), hemophagocytic lymphohistiocytosis (4% (2/50)), aplastic anaemia (2% (1/50)), acquired haemophilia A (2% (1/50)) and coagulation deficiency (2% (1/50)). Simultaneous thrombocytopenia and neutropenia occurred in two patients, concurrent anaemia and thrombocytopenia in one patient. Other than cessation of ICI (in 60%) and corticosteroids (in 78%), treatment included second-line immunosuppression in 24% of cases. Events resolved in 78% (39/50), while 18% (9/50) had persistent changes, and 2% (1/50) had fatal outcomes (agranulocytosis). CONCLUSION: Hem-irAE can affect all haematopoietic blood cell lineages and may persist or even be fatal. Management may require immunosuppression beyond corticosteroids. Although these irAE are rare, treating physicians should be aware, monitor blood counts regularly and promptly act upon detection.

Clinical, FDG-PET and molecular markers of immune checkpoint inhibitor response in patients with metastatic Merkel cell carcinoma.

BACKGROUND: Metastatic Merkel cell carcinoma (mMCC) is an aggressive neuroendocrine malignancy of the skin with a poor prognosis. Immune checkpoint inhibitors (ICIs) have shown substantial efficacy and favorable safety in clinical trials. METHODS: Medical records of patients (pts) with mMCC treated with ICIs from August 2015 to December 2018 at Peter MacCallum Cancer Centre in Australia were analyzed. Response was assessed with serial imaging, the majority with FDG-PET/CT scans. RNA sequencing and immunohistochemistry for PD-L1, CD3 and Merkel cell polyomavirus (MCPyV) on tumor samples was performed. RESULTS: 23 pts with mMCC were treated with ICIs. A median of 8 cycles (range 1 to 47) were administered, with treatment ongoing in 6 pts. Objective responses (OR) were observed in 14 pts (61%): 10 (44%) complete responses (CR) and 4 (17%) partial responses (PR). Median time to response was 8 weeks (range 6 to 12) and 12-month progression-free survival rate was 39%. Increased OR were seen in pts aged less than 75 (OR 80% vs 46%), no prior history of chemotherapy (OR 64% vs 50%), patients with an immune-related adverse event (OR 100% vs 43%) and in MCPyV-negative tumors (OR 69% vs 43%). Pts with a CR had lower mean metabolic tumor volume on baseline FDG-PET/CT scan (CR: 35.7 mL, no CR: 187.8 mL, p=0.05). There was no correlation between PD-L1 positivity and MCPyV status (p=0.764) or OR (p=0.245). 10 pts received radiation therapy (RT) during ICI: 4 pts started RT concurrently (OR 75%, CR 50%), 3 pts had isolated ICI-resistant lesions successfully treated with RT and 3 pts with multisite progression continued to progress despite RT. Overall, 6 pts (26%) had grade 1-2 immune-related adverse events. CONCLUSION: ICIs showed efficacy and safety in mMCC consistent with trial data. Clinical and imaging predictors of response were identified.

Refusal of colorectal cancer surgery in the United States: Predictors and associated cancer-specific mortality in a Surveillance, Epidemiology, and End Results (SEER) cohort.

INTRODUCTION: This study aims to understand patient factors associated with refusal of surgery for nonmetastatic colorectal cancer and the associated cancer-specific mortality. METHODS: Patients diagnosed with nonmetastatic colorectal cancer between 2004 and 2015 from the Surveillance, Epidemiology, and End Results Program were included. RESULTS: A total of 152,731 (99.4%) patients underwent surgery, and 983 (0.6%) refused surgery. Independent predictors of refusal included male sex, older age, minority race, single relationship status, being uninsured, more recent date of diagnosis, having an earlier stage of diagnosis, and rectal versus colon cancer. Refusing surgery for nonmetastatic colorectal cancer increased cancer-specific mortality (adjusted hazard ratio 5.10, 95% confidence interval 4.62-5.62). CONCLUSION: Most patients diagnosed with nonmetastatic colorectal cancer undergo surgery in the United States. However, refusal of surgery is increasing and associated with higher cancer-specific mortality. A better understanding of surgical decision making in colorectal cancer is urgently needed.

Longitudinal Monitoring of ctDNA in Patients with Melanoma and Brain Metastases Treated with Immune Checkpoint Inhibitors.

PURPOSE: Brain involvement occurs in the majority of patients with metastatic melanoma. The potential of circulating tumor DNA (ctDNA) for surveillance and monitoring systemic therapy response in patients with melanoma brain metastases merits investigation. EXPERIMENTAL DESIGN: This study examined circulating BRAF, NRAS, and c-KIT mutations in patients with melanoma with active brain metastases receiving PD-1 inhibitor-based therapy. Intracranial and extracranial disease volumes were measured using the sum of product of diameters, and response assessment performed using RECIST. Longitudinal plasma samples were analyzed for ctDNA over the first 12 weeks of treatment (threshold 2.5 copies/mL plasma). RESULTS: Of a total of 72 patients, 13 patients had intracranial metastases only and 59 patients had concurrent intracranial and extracranial metastases. ctDNA detectability was 0% and 64%, respectively, and detectability was associated with extracranial disease volume (P < 0.01). Undetectable ctDNA on-therapy was associated with extracranial response (P < 0.01) but not intracranial response. The median overall survival in patients with undetectable (n = 34) versus detectable (n = 38) ctDNA at baseline was 39.2 versus 10.6 months [HR, 0.51; 95% confidence interval (CI), 0.28-0.94; P = 0.03] and on-therapy was 39.2 versus 9.2 months (HR, 0.32; 95% CI, 0.16-0.63; P < 0.01). CONCLUSIONS: ctDNA remains a strong prognostic biomarker in patients with melanoma with brain metastases, especially in patients with concurrent extracranial disease. However, ctDNA was not able to detect or monitor intracranial disease activity, and we recommend against using ctDNA as a sole test during surveillance and therapeutic monitoring in patients with melanoma.

FDG PET/CT for tumoral and systemic immune response monitoring of advanced melanoma during first-line combination ipilimumab and nivolumab treatment.

PURPOSE: We aimed to investigate the role of FDG-PET/CT in monitoring of response and immune-related adverse events (irAEs) following first-line combination-immune checkpoint inhibitor (combination-ICI) therapy for advanced melanoma. METHODS: We retrospectively reviewed outcomes in patients who had (1) first-line nivolumab plus ipilimumab; (2) pre- and post-treatment FDG-PET/CT scans (pre-FDG-PET/CT and post-FDG-PET/CT) within 2 and 4 months of starting ICI, respectively; and (3) at least one lesion assessable by PET response criteria in solid tumors (PERCIST). Extracranial response was monitored by 3 monthly FDG-PET/CT. Whole-body metabolic tumor volume (wbMTV) was measured pre- and post-treatment and correlated with outcome. FDG-PET/CT manifestations of irAE were defined as new increased non-tumoral uptake on post-FDG-PET/CT and were correlated with clinical presentation. RESULTS: Thirty-one consecutive patients, median age 60 years (range, 30-78), were identified from 2016 to 2018. The median number of combination-ICI cycles to the first post-FDG-PET/CT response assessment was 3 (interquartile range (IQR), 2-4). The best-overall responses were complete metabolic response (CMR) in 25 (80%), partial metabolic response (PMR) in 3 (10%), and progressive metabolic disease (PMD) in 3 (10%) patients. Patients with PMD had significantly higher pre-treatment wbMTV (p = 0.009). At a median follow-up of 21.5 months, 26 (84%) patients were alive with median progression-free and overall survival not reached. Secondary progression occurred in 9/31 (29%) patients at a median of 8.2 months (IQR, 6.9-15.5), of those majority (78%) was detected by FDG-PET/CT. Of 36 findings on post-FDG-PET/CT suggestive of irAE, 29 (80%) had clinical confirmation. In 3 (7%), the FDG-PET/CT findings preceded clinical presentation. The most common FDG-PET/CT detectable irAEs were endocrinopathies (36%) and enterocolitis (35%). CONCLUSION: FDG-PET/CT response evaluation predicts the long-term outcome of patients treated with first-line combination-ICIs. Long-term treatment response monitoring for detection of extracranial secondary progression is feasible by FDG-PET/CT. Beyond response assessment, FDG-PET/CT frequently detects clinically relevant irAEs, which may involve multiple systems contemporaneously or at various time-points and may precede clinical diagnosis.

A closer look at immune-mediated myocarditis in the era of combined checkpoint blockade and targeted therapies.

Immune checkpoint inhibitors (ICI) and tyrosine kinase inhibitors (TKI) have transformed the management of many malignancies. Although rare, immune-mediated myocarditis presents unique clinical challenges due to heterogenous presentation, potential life-threatening consequences, and the time-critical need to differentiate it from other causes of cardiac dysfunction. Increasingly, TKI are being combined with ICI to promote immune modulation and improve efficacy. However, these combinations are associated with more toxicities. This series describes six patients with advanced melanoma who developed immune-mediated myocarditis while receiving an anti-PD-1 antibody or an anti-PD-L1 antibody plus a mitogen-activated protein kinase inhibitor. It provides a review of their heterogenous clinical presentations, investigational findings and treatment outcomes. Presentations ranged from asymptomatic cardiac enzyme elevation to death due to heart failure. We highlight the role of cardiac MRI (CMRI), a sensitive and non-invasive tool for the early detection and subsequent monitoring of myocardial inflammation. Five of the six patients exhibited CMRI changes characteristic of myocarditis, including mid-wall myocardial oedema and late gadolinium enhancement in a non-coronary distribution. Critically, two of these patients had normal findings on echocardiogram. Of the five patients who received immunosuppression, four recovered from myocarditis and one died of cardiac failure. The sixth patient improved with cardiac failure management alone. Three of the four patients responding to ICI derived long-term benefit. Clinical vigilance, prompt multimodal diagnosis and multidisciplinary management are paramount for the treatment of immune-mediated myocarditis.