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Purpose:Combination immunotherapy with anti–CTLA-4 and anti–PD-1 blockade has demonstrated significant clinical activity across several tumor types. Neuroendocrine tumors (NET) are a heterogeneous group of rare tumors with limited treatment options. CA209-538 is a clinical trial of combination immunotherapy with ipilimumab and nivolumab in rare cancers, including advanced NETs.Patients and Methods:CA209-538 is a prospective multicenter clinical trial in patients with advanced rare cancers. Patients received treatment with nivolumab at a dose of 3 mg/kg and ipilimumab at 1 mg/kg every three weeks for four doses, followed by nivolumab 3 mg/kg every two weeks and continued for up to 96 weeks, until disease progression or the development of unacceptable toxicity. Response was assessed every 12 weeks by RECIST 1.1. The primary endpoint was clinical benefit rate (CBR; complete remission + partial remission + stable disease).Results:Twenty-nine patients with advanced NETs received treatment. Three (10%) patients had low-, 13 (45%) had intermediate-, and 13 (45%) had high-grade tumors; lung was the most common primary site (39%). The objective response rate was 24% with a CBR of 72%; 43% of patients with pancreatic neuroendocrine neoplasms (NEN), and 33% of patients with atypical bronchial carcinoid achieved an objective response. The median progression-free survival was 4.8 months [95% confidence interval (CI): 2.7–10.5] and overall survival was 14.8 months (95% CI: 4.1–21.3). Immune-related toxicity was reported in 66% of patients with 34% experiencing grade 3/4 events.Conclusions:Combination immunotherapy with ipilimumab and nivolumab demonstrated significant clinical activity in subgroups of patients with advanced NETs including patients with atypical bronchial carcinoid and high-grade pancreatic NENs.

In high-grade serous ovarian carcinoma (HGSC), deleterious mutations in DNA repair gene RAD51C are established drivers of defective homologous recombination and are emerging biomarkers of PARP inhibitor (PARPi) sensitivity. RAD51C promoter methylation (meRAD51C) is detected at similar frequencies to mutations, yet its effects on PARPi responses remain unresolved.In this study, three HGSC patient-derived xenograft (PDX) models with methylation at most or all examined CpG sites in the RAD51C promoter show responses to PARPi. Both complete and heterogeneous methylation patterns were associated with RAD51C gene silencing and homologous recombination deficiency (HRD). PDX models lost meRAD51C following treatment with PARPi rucaparib or niraparib, where a single unmethylated copy of RAD51C was sufficient to drive PARPi resistance. Genomic copy number profiling of one of the PDX models using SNP arrays revealed that this resistance was acquired independently in two genetically distinct lineages.In a cohort of 12 patients with RAD51C-methylated HGSC, various patterns of meRAD51C were associated with genomic “scarring,” indicative of HRD history, but exhibited no clear correlations with clinical outcome. Differences in methylation stability under treatment pressure were also observed between patients, where one HGSC was found to maintain meRAD51C after six lines of therapy (four platinum-based), whereas another HGSC sample was found to have heterozygous meRAD51C and elevated RAD51C gene expression (relative to homozygous meRAD51C controls) after only neoadjuvant chemotherapy.As meRAD51C loss in a single gene copy was sufficient to cause PARPi resistance in PDX, methylation zygosity should be carefully assessed in previously treated patients when considering PARPi therapy.Significance:Homozygous RAD51C methylation is a positive predictive biomarker for sensitivity to PARP inhibitors, whereas a single unmethylated gene copy is sufficient to confer resistance.

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In high-grade serous ovarian carcinoma (HGSC), deleterious mutations in DNA repair gene RAD51C are established drivers of defective homologous recombination and are emerging biomarkers of PARP inhibitor (PARPi) sensitivity. RAD51C promoter methylation (meRAD51C) is detected at similar frequencies to mutations, yet its effects on PARPi responses remain unresolved. In this study, three HGSC patient-derived xenograft (PDX) models with methylation at most or all examined CpG sites in the RAD51C promoter show responses to PARPi. Both complete and heterogeneous methylation patterns were associated with RAD51C gene silencing and homologous recombination deficiency (HRD). PDX models lost meRAD51C following treatment with PARPi rucaparib or niraparib, where a single unmethylated copy of RAD51C was sufficient to drive PARPi resistance. Genomic copy number profiling of one of the PDX models using SNP arrays revealed that this resistance was acquired independently in two genetically distinct lineages. In a cohort of 12 patients with RAD51C-methylated HGSC, various patterns of meRAD51C were associated with genomic “scarring,” indicative of HRD history, but exhibited no clear correlations with clinical outcome. Differences in methylation stability under treatment pressure were also observed between patients, where one HGSC was found to maintain meRAD51C after six lines of therapy (four platinum-based), whereas another HGSC sample was found to have heterozygous meRAD51C and elevated RAD51C gene expression (relative to homozygous meRAD51C controls) after only neoadjuvant chemotherapy. As meRAD51C loss in a single gene copy was sufficient to cause PARPi resistance in PDX, methylation zygosity should be carefully assessed in previously treated patients when considering PARPi therapy. Significance: Homozygous RAD51C methylation is a positive predictive biomarker for sensitivity to PARP inhibitors, whereas a single unmethylated gene copy is sufficient to confer resistance.

Purpose: Combination immunotherapy with anti–CTLA-4 and anti–PD-1 blockade has demonstrated significant clinical activity across several tumor types. Neuroendocrine tumors (NET) are a heterogeneous group of rare tumors with limited treatment options. CA209-538 is a clinical trial of combination immunotherapy with ipilimumab and nivolumab in rare cancers, including advanced NETs. Patients and Methods: CA209-538 is a prospective multicenter clinical trial in patients with advanced rare cancers. Patients received treatment with nivolumab at a dose of 3 mg/kg and ipilimumab at 1 mg/kg every three weeks for four doses, followed by nivolumab 3 mg/kg every two weeks and continued for up to 96 weeks, until disease progression or the development of unacceptable toxicity. Response was assessed every 12 weeks by RECIST 1.1. The primary endpoint was clinical benefit rate (CBR; complete remission + partial remission + stable disease). Results: Twenty-nine patients with advanced NETs received treatment. Three (10%) patients had low-, 13 (45%) had intermediate-, and 13 (45%) had high-grade tumors; lung was the most common primary site (39%). The objective response rate was 24% with a CBR of 72%; 43% of patients with pancreatic neuroendocrine neoplasms (NEN), and 33% of patients with atypical bronchial carcinoid achieved an objective response. The median progression-free survival was 4.8 months [95% confidence interval (CI): 2.7–10.5] and overall survival was 14.8 months (95% CI: 4.1–21.3). Immune-related toxicity was reported in 66% of patients with 34% experiencing grade 3/4 events. Conclusions: Combination immunotherapy with ipilimumab and nivolumab demonstrated significant clinical activity in subgroups of patients with advanced NETs including patients with atypical bronchial carcinoid and high-grade pancreatic NENs.

There is now evidence that gene fusions activating the MAPK pathway are relatively common in pancreatic acinar cell carcinoma with potentially actionable BRAF or RET fusions being found in ~30%. We sought to investigate the incidence of RAF1 fusions in pancreatic malignancies with acinar cell differentiation. FISH testing for RAF1 was undertaken on 30 tumors comprising 25 'pure' acinar cell carcinomas, 2 mixed pancreatic acinar-neuroendocrine carcinomas, 1 mixed acinar cell-low grade neuroendocrine tumor and 2 pancreatoblastomas. RAF1 rearrangements were identified in 5 cases and confirmed by DNA and RNA sequencing to represent oncogenic fusions (GATM-RAF1, GOLGA4-RAF1, PDZRN3-RAF1, HERPUD1-RAF1 and TRIM33-RAF1) and to be mutually exclusive with BRAF and RET fusions, as well as KRAS mutations. Large genome-wide copy number changes were common and included 1q gain and/or 1p loss in all five RAF1 FISH-positive acinar cell carcinomas. RAF1 expression by immunohistochemistry was found in 3 of 5 (60%) of fusion-positive cases and no FISH-negative cases. Phospho-ERK1/2 expression was found in 4 of 5 RAF1-fusion-positive cases. Expression of both RAF1 and phospho-ERK1/2 was heterogeneous and often only detected at the tumor-stroma interface, thus limiting their clinical utility. We conclude that RAF1 gene rearrangements are relatively common in pancreatic acinar cell carcinomas (14.3% to 18.5% of cases) and can be effectively identified by FISH with follow up molecular testing. The combined results of several studies now indicate that BRAF, RET or RAF1 fusions occur in between one third and one-half of these tumors but are extremely rare in other pancreatic malignancies. As these fusions are potentially actionable with currently available therapies, a strong argument can be made to perform FISH or molecular testing on all pancreatic acinar cell carcinomas.

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. 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. 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%). 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.

Purpose Circulating tumor DNA (ctDNA) allows noninvasive disease monitoring across a range of malignancies. In metastatic melanoma, the extent to which ctDNA reflects changes in metabolic disease burden assessed by 18F-labeled fluorodeoxyglucose positron emission tomography (FDG-PET) is unknown. We assessed the role of ctDNA analysis in combination with FDG-PET to monitor tumor burden and genomic heterogeneity throughout treatment. Patients and Methods We performed a comprehensive analysis of serial ctDNA and FDG-PET in 52 patients who received systemic therapy for metastatic melanoma. Next-generation sequencing and digital polymerase chain reaction were used to analyze plasma samples from the cohort. Results ctDNA levels were monitored across patients with mutant BRAF, NRAS, and BRAF/NRAS wild type disease. Mutant BRAF and NRAS ctDNA levels correlated closely with changes in metabolic disease burden throughout treatment. TERT promoter mutant ctDNA levels also paralleled changes in tumor burden, which provide an alternative marker for disease monitoring. Of note, subcutaneous and cerebral disease sites were not well represented in plasma. Early changes in ctDNA and metabolic disease burden were important indicators of treatment response. Patients with an early decrease in ctDNA post-treatment had improved progression-free survival compared with patients in whom ctDNA levels remained unchanged or increased over time (hazard ratio, 2.6; P = .05). ctDNA analysis contributed key molecular information through the identification of putative resistance mechanisms to targeted therapy. A detailed comparison of the genomic architecture of plasma and multiregional tumor biopsy specimens at autopsy revealed the ability of ctDNA to comprehensively capture genomic heterogeneity across multiple disease sites. Conclusion The findings highlight the powerful role of ctDNA in metastatic melanoma as a complementary modality to functional imaging that allows real-time monitoring of both tumor burden and genomic changes throughout therapy.

BackgroundMelanoma 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.MethodsPatients 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.ResultsTwenty-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 ConclusionsSecond-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.

Our aim was to investigate sebaceous differentiation in thymus tumours and to identify new actionable genomic alterations. To this end we screened 35 normal and 23 hyperplastic thymuses, 127 thymomas and 41 thymic carcinomas for the presence of sebaceous differentiation as defined by morphology and expression of adipophilin and androgen receptor (AR). One primary thymic carcinoma showed morphology of sebaceous carcinomas (keratinizing and foam cells, calcifications, giant cells), a strong expression of adipophilin and AR together with squamous markers. NGS revealed high-level amplification of fibroblast growth factor receptor 2 (FGFR2). In thymuses and thymomas, no cells with sebaceous morphology were present. Occasionally, macrophages or epithelial cells showed adipophilin-positivity, however, without co-expression of AR. Thymic sebaceous carcinoma should be considered if a thymic carcinoma shows clear or foamy features. Testing for FGFR2 amplification might be warranted when searching for actionable genomic alterations in sebaceous carcinomas in the mediastinum and in other locations.

In high-grade serous ovarian carcinoma (HGSC), deleterious mutations in DNA repair gene

e24127 Background: Patients with a rare cancer (RC) diagnosis face unique challenges affecting psychological wellbeing. Vast geographical distances further compound challenges in accessing RC sub-specialist expertise, clinical trials, research and non-reimbursed therapies. The Australian Rare Cancer (ARC) Portal is a novel model of care delivery that has a positive psychological impact on these patients. Methods: The ARC Portal is a national free online referral platform implemented to overcome barriers to accessing excellent care. It is funded by Omico, with support from BioGrid Australia, Rare Cancers Australia (RCA), and The WEHI Stafford Fox Rare Cancer Program (SFRCP). We have recorded 924 referrals for a diverse range of RC in early (30%) and late stages (70%). Our 162 referring clinicians derive from every Australian state and from both regional and metropolitan centres. Over 50 content experts from Australia and internationally have provided case advice. Referring clinical impact surveys and patient feedback surveys were analysed to identify psychosocial impacts of the ARC Portal. Results: Our model of care keeps patients with their primary oncologists by equipping referrers with increased expertise drawing from, on average, two to five experts. The entirely online consent process overcomes geographical barriers to enrolment, and is of particular importance in the context of the ongoing COVID-19 restrictions removing in person interaction. Provision of expertise and treatment recommendations meets informational needs and increased the patient confidence patients in their treating clinicians. Report recommendations directly altered the treatment delivered to patients in 20/48 of surveyed referrer respondents. Early stage patients are eligible for referral to guide neoadjuvant and adjuvant therapy, and those in remission for anticipatory identification of next lines of therapy. We identify appropriate access to investigator-driven research efforts to overcome financial barriers to genomic sequencing e.g. via the MoST Program funded by OMICO and the WEHI-SFRCP enabling access to molecularly-guided therapy. A lack of reimbursed therapeutic options in RC poses financial stress on patients. The ARC Portal expands patients’ treatment options via links with clinical trial networks, coordination with industry, and cross-referral to the charity, RCA, for fundraising assistance. We provide patients with the opportunity for involvement in research, which for many provides hope, either for themselves, or for others, as they can opt to provide access to biomarker and tumour specimens via the WEHI-SFRCP; the majority of patients (82.5%) have provided consent. Conclusions: The ARC Portal offers patients access to excellent rare cancer care resulting in positive impacts upon patients’ psychological wellbeing. These initial observations require more formal assessment.

e18581 Background: Rare cancers (RC) occur at incidence < 6/100,000 and accessing treatment and evidence-based care can be challenging. Australia’s geographical distance adds complexity when referring to RC sub-specialists, clinical trials or research. The Australian Rare Cancer (ARC) Portal aims to address this unmet need. Methods: The ARC Portal is a free online academic referral hub designed to facilitate rare cancer clinical care and research. Registered cancer specialists can request RC guidelines, expert advice and molecular testing/interpretation. Patient consent allows researchers access to de-identified clinical data, with optional consent for biospecimen access, for dedicated rare cancer research projects (Melbourne Health HREC/15/MH/396). Portal case reports are collated by research fellows with reference to published evidence and expert opinion to inform treating clinician decision making. Surveys are sent at 3 time points following case completion to assess the ARC Portal impact on patient management. The ARC Portal is funded by Omico, with support from BioGrid Australia, Rare Cancers Australia and the Stafford Fox Rare Cancer Program. Results: Over two years, 924 patients have been enrolled into the ARC Portal. Demographics include 73% females, 27% males, at different disease stages from initial diagnosis (23%), on relapse/ progression (48%) or with stable disease/in remission (29%). The spread of incidence of individual cancers varied from 6/100,000 to < 0.1/100,000. Primary tumour types include gynaecological (44.4%), gastrointestinal (19%), thoracic (6%), ocular (5.2%), soft tissue (3.8%), breast (3.6%), skin (3.0%), and CNS tumors (2.5%). Endocrine, head and neck, urological, and cancers of unknown primary comprised the remaining 12.5% of cases. Longer term follow up of 100 cases demonstrated ARC Portal reports impacted clinician decision making in at least 42%. This included subsequent lines of treatment, molecular testing access or clinical trial enrolment. Conclusions: The ARC Portal uses an online centralized streamlined approach to overcome challenges and inequities inherent in rare cancer care, by optimizing clinician access to RC expertise and clinical trials; and to facilitate future RC discoveries by enabling research through collection of clinical data and accessible annotated biospecimens.

Background: Adrenocortical carcinoma is a rare malignancy, with poor prognosis and limited treatment options for patients with advanced disease. Chemotherapy is the current standard first-line treatment, providing only a modest survival benefit. There is only limited treatment experience with immunotherapy using single-agent anti-PD-1/PD-L1 therapy. To date no clinical trials have been reported using combination immunotherapy with anti-CTLA-4 and anti-PD-1 blockade in this patient population. Methods: CA209-538 is a prospective multicentre clinical trial in patients with advanced rare cancers. Participants received the anti-PD-1 antibody nivolumab (3 mg/kg IV) and the anti-CTLA-4 antibody ipilimumab (1 mg/kg IV) every three weeks for four doses, followed by nivolumab (3 mg/kg IV) every two weeks and continued for up to 96 weeks, until disease progression or unacceptable toxicity. Response was assessed every 12 weeks by RECIST version 1.1. Primary endpoint was clinical benefit rate (complete response, partial response, stable disease at 12 weeks). Results: Six patients with adrenocortical carcinoma were enrolled and received treatment. Two patients (33%) have an ongoing partial response (10 and 25 months +) and two patients (33%) stable disease leading to a disease control rate of 66%. Both responders had tumors with a microsatellite instable phenotype. One patient rapidly progressed shortly after enrollment into the trial and did not undergo restaging. Immunotherapy-related toxicity was reported in all patients, with four patients (67%) experiencing grade 3/4 hepatitis leading to discontinuation of treatment. Conclusions: This is the first treatment experience using ipilimumab and nivolumab combination immunotherapy in patients with advanced adrenocortical carcinoma. Durable responses have been observed in a subset of patients suggesting that this treatment regimen should be further investigated in this patient population.

While loss of BRCA1 promoter methylation has been shown to cause PARP inhibitor (PARPi) resistance in high-grade serous ovarian carcinoma (HGSC), the impacts of RAD51C methylation (meRAD51C) remain unresolved. In this study, three PARPi-responsive HGSC patient-derived xenografts (PDX) with RAD51C gene silencing and homologous recombination deficiency were found to have either homogeneous or heterogeneous patterns of meRAD51C. PDX could lose meRAD51C following PARPi treatment (rucaparib/niraparib), where a single unmethylated RAD51C copy was sufficient to drive PARPi-resistance. Genomic profiling revealed this resistance was acquired independently in two distinct PDX lineages. Furthermore, we describe a patient sample where 1/3 RAD51C gene copies lost methylation following neoadjuvant chemotherapy. We show meRAD51C is a positive predictive biomarker for PARPi response and should be screened for routinely in patients. However, methylation loss in a single gene copy is sufficient to cause PARPi resistance and should be carefully assessed in previously treated patients considering PARPi therapy.

Importance Biliary tract cancers represent a rare group of malignant conditions with very limited treatment options. Patients with advanced disease have a poor outcome with current therapies. Objective To evaluate the efficacy and safety of combination immunotherapy with nivolumab and ipilimumab in patients with advanced biliary tract cancers. Design, Setting, and Participants The CA209-538 prospective multicenter phase 2 nonrandomized clinical trial included patients with advanced rare cancers including patients with biliary tract cancers. This subgroup analysis evaluated 39 patients from CA209-538 with biliary tract cancers who were enrolled from December 2017 to December 2019. Most of the patients (n = 33) had experienced disease progression after 1 or more lines of therapy and had tumor tissue available for biomarker research. Interventions Patients received treatment with nivolumab at a dose of 3 mg/kg and ipilimumab at 1 mg/kg every 3 weeks for 4 doses, followed by nivolumab 3 mg/kg every 2 weeks and continued for up to 96 weeks until disease progression or the development of unacceptable toxic events. Main Outcomes and Measures The primary end point was disease control rate (complete remission, partial remission, or stable disease) as assessed by RECIST 1.1. Results Among the 39 patients included in this subgroup analysis of a phase 2 clinical trial (20 men, 19 women; mean [range] age, 65 [37-81] years), the objective response rate was 23% (n = 9) with a disease control rate of 44% (n = 17); all responders had received prior chemotherapy, and none had a microsatellite unstable tumor. Responses were exclusively observed in patients with intrahepatic cholangiocarcinoma and gallbladder carcinoma. The median duration of response was not reached (range, 2.5 to ≥23 months). The median progression-free survival was 2.9 months (95% CI, 2.2-4.6 months), and overall survival was 5.7 months (95% CI, 2.7-11.9 months). Immune-related toxic events were reported in 49% of patients (n = 19), with 15% (n = 6) experiencing grade 3 or 4 events. Conclusions and Relevance This subgroup analysis of a phase 2 clinical trial found that combination immunotherapy with nivolumab and ipilimumab was associated with substantial positive outcomes patients with advanced biliary tract cancers. This treatment compares favorably to single-agent anti–programmed cell death protein 1 (anti–PD-1) therapy and warrants further investigation. Ongoing translational research is focused on identifying biomarkers that can predict treatment response. Trial Registration ClinicalTrials.gov Identifier:NCT02923934

Immune-related adverse events (irAEs) are a frequent complication of immunotherapy, but neurological irAEs are rare and varied. Here, we present a case of cerebral amyloid angiopathy-related inflammation (CAA-ri) attributable to nivolumab monotherapy, which has not been previously reported. The context of immunotherapy and availability of serial imaging also provide unique insights into the pathogenesis and evolution of CAA-ri. Routine surveillance neuroimaging in a patient with metastatic melanoma, in remission after treatment with nivolumab, demonstrated progressive microhaemorrhages and associated oedema, suspicious for CAA-ri. These changes progressed despite cessation of nivolumab. The patient was initially asymptomatic, but later developed an acute confusional state, warranting brain biopsy, which confirmed the diagnosis of CAA-ri. Treatment with methylprednisolone resulted in resolution of the oedema, and a marked decrease in the subsequent accumulation of microhaemorrhages. The temporal evolution prior to symptom development and subsequently related to treatment suggests that inflammation may be an important component of the pathogenesis of CAA-ri, rather than simply a secondary response. Given that immunotherapy is in its relative infancy, it is important to consider rare irAEs in patients exhibiting unusual imaging findings.

PURPOSE Rare cancers are challenging for researchers, as clinicians and scientists have difficulty recruiting sufficient patient cases to power studies appropriately. Likewise, patients often are frustrated by a lack of specific information or evidence base for their cancer and, although eager to participate in research, have limited opportunities. We established CART-WHEEL.org, an online patient-entered database, to directly engage patients in the research process, collect rare cancer data, and facilitate their entry into additional research. PATIENTS AND METHODS Patients access CART-WHEEL.org directly online. Clinical information is collected from users via a streamlined questionnaire developed collaboratively with consumer groups to ensure accessibility and relevance. Data collected include the following: patient demographics, comorbidities, and risk factors and tumor diagnostic, biomarker, and treatment history. Patients can download a medical summary for personal use; consent for research use of data; and indicate willingness to be contacted about other research or clinical trials. We describe data collected to date and its validation, and we provide examples of how CART-WHEEL.org can facilitate rare cancer research. RESULTS From January 2010 to March 2018, 558 patients provided consent and entered their rare cancer data. One hundred distinct rare tumor types and patients from 22 countries were included. Validation of data entered by 21 patients with sarcoma against a hospital database demonstrated accuracy sufficient to facilitate future research in key fields, such as tumor site (95%) and histopathologic diagnosis (90%). Examples of CART-WHEEL–based disease-specific projects, subsequent recruitment to other rare cancer projects, and rare cancer patient cases of interest are described. CONCLUSIONS Online platforms like CART-WHEEL.org can engage consumers directly, facilitating collection of patient-entered rare cancer data for hypothesis generation, and connect patients with researchers to enable specific rare cancer research and clinical trials.

BackgroundPatients with rare cancers represent 55% of all gynecological malignancies and have poor survival outcomes due to limited treatment options. Combination immunotherapy with the anti-programmed cell death protein 1 (anti-PD-1) antibody nivolumab and the anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4) antibody ipilimumab has demonstrated significant clinical efficacy across a range of common malignancies, justifying evaluation of this combination in rare gynecological cancers.MethodsThis multicenter phase II study enrolled 43 patients with advanced rare gynecological cancers. Patients received induction treatment with nivolumab and ipilimumab at a dose of 3 mg/kg and 1 mg/kg, respectively, every 3 weeks for four doses. Treatment was continued with nivolumab monotherapy at 3 mg/kg every 2 weeks until disease progression or a maximum of 2 years. The primary endpoint was the proportion of patients with disease control at week 12 (complete response, partial response or stable disease (SD) by Response Evaluation Criteria In Solid Tumor V.1.1). Exploratory evaluations correlated clinical outcomes with tumor programmed death-ligand 1 (PD-L1) expression and tumor mutational burden (TMB).ResultsThe objective response rate in the radiologically evaluable population was 36% (12/33 patients) and in the intention-to-treat population was 28% (12/43 patients), with additional 7 patients obtaining SD leading to a disease control rate of 58% and 44%, respectively. Durable responses were seen across a range of tumor histologies. Thirty-one (72%) patients experienced an immune-related adverse event (irAE) with a grade 3/4 irAE observed in seven (16%) patients. Response rate was higher among those patients with baseline PD-L1 expression (≥1% on tumor cells) but was independent of TMB.ConclusionsIpilimumab and nivolumab combination treatment has significant clinical activity with a favorable safety profile across a range of advanced rare gynecological malignancies and warrants further investigation in these tumor types.

Immunotherapy for advanced melanoma has progressed dramatically in the last five years with the approval of immune checkpoint inhibitors targeting cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1). Inhibition of these targets can break cancer-immune tolerance and result in durable objective responses with significantly improved tolerability over cytokine-based immunotherapy. Ipilimumab is an inhibitor of CTLA-4 and the first-in-class immune checkpoint inhibitor to demonstrate an improvement in overall survival in melanoma. Pembrolizumab and nivolumab target PD-1 and have improved single agent activity and tolerability in comparison to ipilimumab. The combination of nivolumab and ipilimumab results in even better response rates, reductions in tumor volume and progression free survival but at the expense of considerable autoimmune effects. Autoimmune side-effects and non-standard response kinetics represent a new challenge associated with cancer therapies that practitioners will have to become more familiar with as checkpoint inhibitors increasingly become part of mainstream oncological practice. Ongoing areas of investigation include drug development against novel immune targets; alternative treatment modalities, such as genetically modified oncolytic viruses; optimization of immunotherapy combination strategies; and the identification of reliable biomarkers to better guide treatment selection.

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.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.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%).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.

There is now evidence that gene fusions activating the MAPK pathway are relatively common in pancreatic acinar cell carcinoma with potentially actionable BRAF or RET fusions being found in ~30%. We sought to investigate the incidence of RAF1 fusions in pancreatic malignancies with acinar cell differentiation. FISH testing for RAF1 was undertaken on 30 tumors comprising 25 'pure' acinar cell carcinomas, 2 mixed pancreatic acinar-neuroendocrine carcinomas, 1 mixed acinar cell-low grade neuroendocrine tumor and 2 pancreatoblastomas. RAF1 rearrangements were identified in 5 cases and confirmed by DNA and RNA sequencing to represent oncogenic fusions (GATM-RAF1, GOLGA4-RAF1, PDZRN3-RAF1, HERPUD1-RAF1 and TRIM33-RAF1) and to be mutually exclusive with BRAF and RET fusions, as well as KRAS mutations. Large genome-wide copy number changes were common and included 1q gain and/or 1p loss in all five RAF1 FISH-positive acinar cell carcinomas. RAF1 expression by immunohistochemistry was found in 3 of 5 (60%) of fusion-positive cases and no FISH-negative cases. Phospho-ERK1/2 expression was found in 4 of 5 RAF1-fusion-positive cases. Expression of both RAF1 and phospho-ERK1/2 was heterogeneous and often only detected at the tumor-stroma interface, thus limiting their clinical utility. We conclude that RAF1 gene rearrangements are relatively common in pancreatic acinar cell carcinomas (14.3% to 18.5% of cases) and can be effectively identified by FISH with follow up molecular testing. The combined results of several studies now indicate that BRAF, RET or RAF1 fusions occur in between one third and one-half of these tumors but are extremely rare in other pancreatic malignancies. As these fusions are potentially actionable with currently available therapies, a strong argument can be made to perform FISH or molecular testing on all pancreatic acinar cell carcinomas.

Background Autoimmune polyendocrine syndrome type II (APS-2) is a rare constellation of autoimmune hypoadrenalism, thyroid dysfunction and/or type 1 diabetes (T1DM), usually occurring in the 3rd or 4th decades and associated with a human leukocyte antigen (HLA) DR3 or DR4 serotype. We detail the first report of an elderly woman developing the full triad of APS-2 shortly after commencing anti-programmed cell death protein 1 (anti-PD1) immune checkpoint inhibition for unresectable melanoma and review the literature for similar presentations secondary to anti-PD1 axis therapy. Case A 78-year-old female with advanced unresectable BRAF wild-type melanoma was treated with pembrolizumab (2 mg/kg 3-weekly). Three weeks following the first dose she developed fulminant autoimmune diabetes, with an initially low C-peptide denoting rapid destruction of ß-islet cells. Following stabilisation of her diabetes, two further doses of pembrolizumab was administered. She then represented with symptomatic hypoadrenalism and hypothyroidism, consistent with APS-2. Her HLA class II genotype was HLA-DRB1*04.16 (DR4 serotype), a recognised association with this syndrome. Her melanoma responded rapidly to anti-PD1 therapy, and a complete response (CR) was attained after four doses of pembrolizumab. Treatment was discontinued and her CR is ongoing. Conclusion This is the first report of the full triad of APS-2 developing in a genetically susceptible individual at the age of 78 after treatment with an anti-PD1 agent. Although scarcely reported, a literature review of similar reports seems to indicate a predilection for this syndrome in patients with HLA-DR4 serotypes. HLA Class II typing is not routinely recommended, but may provide useful predictive information for patients at risk of poly-endocrinopathy even in patients without a relevant personal or family history. Additional studies are required to determine if such testing would be useful and/or cost effective. Electronic supplementary material The online version of this article (10.1186/s40425-019-0713-y) contains supplementary material, which is available to authorized users.

6091 Background: Up to 50% of gynecological cancers are considered rare. The outcome of these patients (pts) is poor given a lack of scientific and clinical knowledge. Immunotherapy using single agent anti- PD-1/PD-L1 treatment (tx) has shown only modest activity in patients with common gynecological malignancies, such as high grade serous ovarian cancer (ca) and microsatellite stable endometrial ca. Combined CTLA-4/PD-1 blockade using ipilimumab (ipi) and nivolumab (nivo) has demonstrated superior efficacy compared to single agent anti-PD-1 therapy in pts with advanced melanoma and renal cell ca. To date, no trials have been undertaken with ipi/nivo in patients with rare gynecological malignancies. Methods: 41 pts with advanced rare gynecological malignancies were enrolled into the CA209-538 trial. Pts received nivo 3mg/kg and ipi 1mg/kg q 3 weekly for four doses, followed by nivo 3mg/kg q 2 weekly. Tx continued for up to 96 weeks, or until disease progression or the development of unacceptable toxicity. Response (RECIST 1.1) was assessed every 12 weeks. The primary endpoint was clinical benefit rate (CBR = CR +PR + SD). Exploratory endpoints include correlation of efficacy with biomarkers (incl PD-L1/TMB). Results: Pts with 10 rare tumor types were enrolled (Table). 39/41 pts have received prior therapy (1-7 lines). Objective responses were observed in 11 pts (27%) including pts with vaginal SCC, ovarian clear cell and low grade serous ca, ovarian and uterine carcinosarcoma, uterine clear cell, uterine serous ca and leiomyosarcoma. A further 9 pts had SD as their best radiological response resulting in a CBR of 49%. The median duration of response had not been reached (range 3.5 – 25+ months) with seven responses being ongoing. 63% of pts experienced an immune related adverse event (irAEs) with 4 pts developing Grade 3/4 irAEs. Conclusions: Ipi/Nivo tx demonstrates efficacy in a range of different rare gynecological cancers with a significant number of durable responses being observed. Tumor agnostic biomarkers are required to assist with better patient selection. Clinical trial information: NCT02923934. [Table: see text]

103 Background: Rare cancers (RCs) often lack proven treatments and consequently have poorer outcomes. Identification of molecular biomarkers can facilitate treatment selection and trials access for RC patients (pts) where histology-based trials are not feasible. We assessed the potential for next-generation sequencing (NGS) to impact RC care. Methods: Pts with a rare histology, poor-prognosis solid-tumor and no standard of care therapy underwent NGS genomic profiling of paired FFPE tumor and blood (PMCC comprehensive cancer panel; 391 genes). A virtual molecular tumour board (MTB) reviewed curated results regarding diagnosis, actionability (OncoKB) and treatment recommendations. Results: Between July 2017 and Nov 2019, 121 pt were prospectively enrolled across 4 Australian sites. 109 (91%) pts had a tumour with an incidence of < 1/100,000 person/years with 83 diverse RC histologies represented. 100 (83%) cases were successfully sequenced. The most commonly aberrant genes ( > 10%) were: TP53 (45%), CDKN2A/B, RB1, PTEN and NF1. 51 (51%) had at least one potentially actionable finding, with 27 matched to a clinically validated drug (OncoKB level 3 or better) [Table]. In 6 cases NGS resulted in a revised diagnosis (includes 4 with FDA approved therapy). Actionable germline mutations were detected in 3 individuals of which 2 were previously known. The majority of pts remain in follow-up, however, 8 died prior to or within 28 days of NGS result availability. Drug access remains a limitation with only 12 receiving therapy based on NGS/MTB guidance. Clinical trial information: ACTRN12616001000493 . Conclusions: NGS in RCs is feasible with potential impact in half of cases. Earlier testing and improved off-label/trial drug access is necessary to increase the likelihood that RC patients may benefit from molecularly guided therapy. [Table: see text]

4588 Background: Patients (pts) with advanced biliary tract cancers (BTC) have a poor prognosis with first and second line chemotherapy resulting in modest survival benefits. Immunotherapy using single agent anti-PD-1 therapy has also shown low activity with an objective response rate (ORR) of less than 10%. Combined CTLA-4/PD-1 blockade using ipilimumab (ipi) and nivolumab (nivo) has demonstrated superior efficacy compared to single agent anti-PD-1 therapy in pts with advanced melanoma and renal cell carcinoma. To date, no trials in BTC pts with ipi/nivo therapy have been reported. Methods: 39 pts with metastatic BTCs were enrolled into the CA 209-538 clinical trial for rare cancers. Patients received nivo 3mg/kg and ipi 1mg/kg q 3 weekly for 4 doses, followed by nivo 3mg/kg q 2 weekly. Treatment continued for up to 96 weeks, or until disease progression or the development of unacceptable toxicity. Response (RECIST 1.1) was assessed every 12 weeks. The primary endpoint was clinical benefit rate (CBR = CR +PR + SD). Exploratory endpoints include correlation of efficacy with biomarkers including PD-L1 expression and tumour mutation burden. Results: 39 pts with BTC were enrolled and 33 pts (85%) had received at least one prior line of systemic treatment (0-2 lines). The ORR was 24% and the CBR 45% with the median duration of response not been reached (range 2-26+months). Responses were observed in 3/14 intrahepatic, 1/10 extrahepatic, 0/2 unspecified cholangiocarcinoma and 5/13 gallbladder ca pts. None of the responding pts had a microsatellite instable tumour. 2 pts with durable partial responses were subsequently rendered surgically free of disease. Median OS and PFS were 6.1 and 3.1 months respectively. 22 (56%) pts experienced an immune –related adverse event (irAE) with grade3/4 irAEs being observed in 8 (20%) pts. Conclusions: Combination immunotherapy with ipi/nivo demonstrates significant clinical activity in a subset of patients with advanced microsatellite stable BTC. The response rate compares favourably to clinical trials investigating single agent anti-PD-1 therapy. Clinical trial information: NCT02923934 .

2033 Background: Despite increasing evidence of benefit supporting CGP in personalizing cancer therapy, its widespread uptake remains limited. Barriers include low patient understanding, unmet patient expectations related to low utility, clinician concerns over cost-effectiveness, perceived value, and discomfort in management of complex genomic results. Methods: This prospective cross-institutional demonstration study was designed to evaluate implementation of CGP in the care of adult and paediatric advanced cancer pts, incorporating pt reported outcomes (PROMs), discrete choice experiment (DCE), ongoing process optimization and clinician evaluations. DNA sequencing of FFPE tumor and matched blood was completed with CGP (PMCC Comprehensive Cancer Panel; 391 genes) via central laboratory. A tumor board reported results weekly with emphasis on therapeutic relevance. Oncologists performed consent and results delivery. Pts completed pre-and post-test surveys, including validated and study-specific questions, DCE and if eligible, semi-structured interviews. Qualitative interviews were undertaken with study clinicians and laboratory staff to evaluate processes. Results: 86% (315) of 365 enrolled pts had successful CGP; of these 63% (199) had relevant therapeutic, diagnostic or germline results. 50 (16%) had treatment change at 6m, 49 (16%) had germline mutations. 293 (88% of adult pts) completed PROMs. 17 of 19 clinicians/laboratory staff approached consented to an interview. At consent pts cited multifaceted value in testing, showed good understanding of basic concepts, but most (69%) overestimated the likelihood of result-led change. Post-test pts remained consistently satisfied with accessing CGP; valuing research contribution, taking opportunities and information for family. 21% struggled with understanding results but there were low levels of decisional regret following participation (89% had nil/mild regret). Pt-elicited preferences (via DCE) indicated priority for high rates of clinical utility and timeliness. Clinicians sited collaboration and communication as critical to delivery of CGP. Conclusions: Pts undergoing CGP are generally satisfied, and derive value on its use beyond potential therapeutic benefit. Our results suggest that to improve test utility and delivery of CGP with value to pts and investing institution, focus must be placed on addressing the additional barriers to its wider implications including efforts to improve process efficiencies, clinician genomic literacy and decision-making support.

Background As early detection of recurrent melanoma maximizes treatment options, patients usually undergo post-operative imaging surveillance, increasingly with FDG-PET/CT (PET). To assess this, we evaluated stage 3 melanoma patients who underwent prospectively applied and sub-stage-specific schedules of PET surveillance. Patients and methods From 2009, patients with stage 3 melanoma routinely underwent PET +/− MRI brain scans via defined schedules based on sub-stage-specific relapse probabilities. Data were collected regarding patient characteristics and outcomes. Contingency analyses were carried out of imaging outcomes. Results One hundred and seventy patients (stage 3A: 34; 3B: 93; 3C: 43) underwent radiological surveillance. Relapses were identified in 65 (38%) patients, of which 45 (69%) were asymptomatic. False-positive imaging findings occurred in 7%, and 6% had treatable second (non-melanoma) malignancies. Positive predictive values (PPV) of individual scans were 56%−83%. Negative scans had predictive values of 89%−96% for true non-recurrence [negative predictive values (NPV)] until the next scan. A negative PET at 18 months had NPVs of 80%−84% for true non-recurrence at any time in the 47-month (median) follow-up period. Sensitivity and specificity of the overall approach of sub-stage-specific PET surveillance were 70% and 87%, respectively. Of relapsed patients, 33 (52%) underwent potentially curative resection and 10 (16%) remained disease-free after 24 months (median). Conclusions Application of sub-stage-specific PET in stage 3 melanoma enables asymptomatic detection of most recurrences, has high NPVs that may provide patient reassurance, and is associated with a high rate of detection of resectable and potentially curable disease at relapse.