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Background Outcomes for patients with metastatic renal cell carcinoma (mRCC) and tumour thrombus remain poor. Recent data suggest limited role for cytoreductive nephrectomy (CN) and data on thrombus response to systemic therapy (ST) is scarce. Here, we describe response and survival of patients with de novo mRCC and thrombi treated with ST with or without CN. Methods Demographics, disease characteristics and survival of patients with de novo mRCC were collected. Progression-free survival (PFS) and overall survival (OS) in months (m) was calculated using the Kaplan–Meier method (log-rank). Results Between 2002 and 2019, 226 patients with mRCC were identified, 64 (28.3%) had tumour thrombus out of which 18 (28.1%) received only ST. Among 12 evaluable patients, thrombus response, stability and progression were seen in 3 (25%), 6 (50%) and 3 (25%) patients, respectively. Median OS was similar for patients with and without tumour thrombus treated with systemic therapy alone [OS: 12.1 m (8.8–27.7) vs. 13.9 m (7.9–21.5), p = 0.87]. CN predicted for better OS in patients with tumour thrombus [OS: 29.4 m (17.4–48.9) vs. 12.1 m (8.8–27.7), p = 0.01]. Conclusion In this retrospective series of patients with mRCC and tumour thrombus, addition of CN to ST improved outcomes. Validation of these findings with contemporary regimens is needed.

Ovarian high-grade serous carcinoma (HGSC) prognosis correlates directly with presence of intratumoral lymphocytes. However, cancer immunotherapy has yet to achieve meaningful survival benefit in patients with HGSC. Epigenetic silencing of immunostimulatory genes is implicated in immune evasion in HGSC and re-expression of these genes could promote tumor immune clearance. We discovered that simultaneous inhibition of the histone methyltransferases G9A and EZH2 activates the CXCL10–CXCR3 axis and increases homing of intratumoral effector lymphocytes and natural killer cells while suppressing tumor-promoting FoxP3+ CD4 T cells. The dual G9A/EZH2 inhibitor HKMTI-1–005 induced chromatin changes that resulted in the transcriptional activation of immunostimulatory gene networks, including the re-expression of elements of the ERV-K endogenous retroviral family. Importantly, treatment with HKMTI-1–005 improved the survival of mice bearing Trp53−/− null ID8 ovarian tumors and resulted in tumor burden reduction. These results indicate that inhibiting G9A and EZH2 in ovarian cancer alters the immune microenvironment and reduces tumor growth and therefore positions dual inhibition of G9A/EZH2 as a strategy for clinical development.

Supplementary Figure from Dual G9A/EZH2 Inhibition Stimulates Antitumor Immune Response in Ovarian High-Grade Serous Carcinoma

Supplementary Table from Dual G9A/EZH2 Inhibition Stimulates Antitumor Immune Response in Ovarian High-Grade Serous Carcinoma

Supplementary Data from Dual G9A/EZH2 Inhibition Stimulates Antitumor Immune Response in Ovarian High-Grade Serous Carcinoma

Ovarian high-grade serous carcinoma (HGSC) prognosis correlates directly with presence of intratumoral lymphocytes. However, cancer immunotherapy has yet to achieve meaningful survival benefit in patients with HGSC. Epigenetic silencing of immunostimulatory genes is implicated in immune evasion in HGSC and re-expression of these genes could promote tumor immune clearance. We discovered that simultaneous inhibition of the histone methyltransferases G9A and EZH2 activates the CXCL10–CXCR3 axis and increases homing of intratumoral effector lymphocytes and natural killer cells while suppressing tumor-promoting FoxP3+ CD4 T cells. The dual G9A/EZH2 inhibitor HKMTI-1–005 induced chromatin changes that resulted in the transcriptional activation of immunostimulatory gene networks, including the re-expression of elements of the ERV-K endogenous retroviral family. Importantly, treatment with HKMTI-1–005 improved the survival of mice bearing Trp53−/− null ID8 ovarian tumors and resulted in tumor burden reduction. These results indicate that inhibiting G9A and EZH2 in ovarian cancer alters the immune microenvironment and reduces tumor growth and therefore positions dual inhibition of G9A/EZH2 as a strategy for clinical development.

Background Despite more than 2 years having elapsed since the onset of SARS-CoV-2 pandemic, a level of hesitation around increased SARS-CoV-2 vaccine toxicity in cancer patients receiving immunotherapy (IO) remains. Here, we explore serological responses to SARS-CoV-2 vaccination in patients treated with IO and we describe blood cytokines, autoantibody levels and immune-related adverse events (irAEs) post vaccination. Methods Serum anti-SARS-CoV-2 spike (S) protein receptor binding domain (RBD) antibodies, surrogate viral neutralization test (sVNT), Th1/Th2 cytokines and antibodies against self-antigens were quantified at baseline, between 1st and 2nd vaccine doses, at 1 week (1W), 1 month (1M), 4–6 months and 10–12 months after the 2nd dose. Grade 2 or higher (≥ gr2+) irAEs were captured prospectively. Results Fifty-one evaluable patients were enrolled in this longitudinal study, 35 on immunotherapy (IO) and 16 on non-immunotherapy (non-IO) treatment. Absolute levels and neutralization potential of anti-SARS-CoV-2 antibodies were not significantly different in the IO group compared to non-IO. Chemotherapy adversely affects seroconversion when compared to IO and/or targeted treatment with antibody levels of 67.6 U/mL vs 1441 U/mL (p = 0.006) and sVNT of 70.9% vs 94.5% (p = 0.009), at 1M after 2nd vaccine dose. Following vaccination, the prevalence of grade ≥ 2 irAEs in patients treated with IO was not higher than the usual reported IO toxicity. We report, for the first time, that post-vaccination, IgM autoantibodies against beta 2 glycoprotein (p = 0.02), myeloperoxidase (p = 0.03), nucleosome (p = 0.041), SPLUNC2 (p

The cancer research community continues to search for additional biomarkers of response and resistance to immune checkpoint treatment (ICT). The ultimate goal is to direct the use of ICT in patients whose tumors are most likely to benefit to achieve a refinement that is equivalent to that of a genotype-matched targeted treatment. Dissecting the mechanisms of ICT resistance can help us characterize ICT nonresponders more efficiently. In this opinion, we argue that there may be additional knowledge gained about immune evasion in cancer by analyzing the loss of the human 9p21.3 locus; as an example, we highlight findings of 9p21.3 loss from the investigator-initiated, pan-cancer INSPIRE study, in which patients were treated with pembrolizumab (anti-PD-1 antibody) ICT.

Recent advances in treating cutaneous melanoma have resulted in impressive patient survival gains. Refinement of disease staging and accurate patient risk classification have significantly improved our prognostic knowledge and ability to accurately stratify treatment. Undoubtedly, the most important step towards optimizing patient outcomes has been the advent of cancer immunotherapy, in the form of immune checkpoint inhibition (ICI). Immunotherapy has established its cardinal role in the management of both early and late-stage melanoma. Through leveraging outcomes in melanoma, immunotherapy has also extended its benefit to other types of skin cancers. In this review, we endeavor to summarize the current role of immunotherapy in melanoma and non-melanoma skin cancers, highlight the most pertinent immunotherapy-related molecular biomarkers, and lastly, shed light on future research directions.

Circulating biomarkers have emerged as valuable surrogates for evaluating disease states in solid malignancies. Their relative ease of access and rapid turnover has bolstered clinical applications in monitoring treatment efficacy and cancer progression. In this review, the roles of various circulating biomarkers in monitoring treatment response are described. Non-specific markers of disease burden, tumor markers (eg CA 125, CEA, PSA, etc.), circulating tumor cells, nucleic acids, exosomes, and metabolomic arrays are highlighted. Specifically, the discovery of each of these markers is reviewed, with examples illustrating their use in influencing treatment decisions, and barriers to their application noted where these exist. Finally, opportunities for future work using these circulating biomarkers are discussed.

9579 Background: High-risk melanoma has variable prognosis. Adjuvant immuno- (IO) and targeted therapy (TT) are approved for stage III-IV resected disease. However, a significant proportion of patients (pts) are cured by local treatment alone or relapse despite adjuvant therapy. Liquid biopsy with ctDNA assays have been used to predict response to treatment and identify pts at higher risk of progression/death. Personalized ctDNA assays are a highly sensitive approach that may enhance upfront risk stratification and early detection of relapse. Methods: Serial ctDNA Monitoring as a predictive Biomarker in advanced neoplAsms (SAMBA) is a Princess Margaret prospective ctDNA kinetics study (NCT03702309) in high-risk melanoma pts. Plasma is collected pre-op (pre-local treatment, if feasible), post-op (after surgery), and every 3-6 months (m) until radiological progressive disease (rPD). Personalized amplicon based NGS assays by Inivata (RaDaR) were used to detect somatic variants in ctDNA identified through whole-exome sequencing of matched tumor tissue. Progression free survival (PFS) and overall survival (OS) from the time of surgery were estimated with the Kaplan Meier and compared with the log-rank test. Results: As of December 2021, 82 of 100 planned pts have been enrolled. A total of 191 samples from 47 pts have been analyzed. Median age was 66 years (27-87), 33 were male (70%). Seven (15%), 30 (64%) and 10 (21%) were stage II/III/IV respectively. All pts had surgery and 8 (17%) adjuvant radiation. No systemic therapy was given to 11 pts (23%); 30 (64%) had IO and 6 (13%) TT. rPD occurred in 13 pts (28%). Median follow up was 24 months. A median of 48 variants were included in the personalized ctDNA panel design (35-52). ctDNA was detected (ctDNA+) at any time point in 12/47 pts (26%), of which 5/12 (42%) were BRAF and NRAS wt on tissue. Median PFS was 4.9 months (m) for ctDNA+ pts and not reached (NR) for ctDNA- pts at post-op (HR = 2.71 CI 0.60-12.31, p = 0.179). Median OS was 23.1 m vs NR in ctDNA+ vs ctDNA- pts (HR = 8.9, CI 1.45-54.77, p = 0.004). Two ctDNA+ pts had neoadjuvant IO and became ctDNA- before surgery. One, free of disease after 12 m, had ctDNA- in 4 follow up samples. The other pt was ctDNA+ in the post-op sample and relapsed within 3 m. Four of 45 (9%) pts had ctDNA+ at post-op. Two of them, including a pt who had neoadjuvant IO, did not receive adjuvant therapy and had rPD within 3 m. The other 2 pts received adjuvant IO; ctDNA cleared and pts remain free of disease at 12 and 34 m. Three pts with rising ctDNA over time experienced rPD after a median of 4 m (2-7). Conclusions: Personalized ctDNA analysis with RaDaR may improve risk of death stratification and selection of pts who could benefit from adjuvant treatment. Detection of ctDNA may precede rPD. Follow-up will continue in pts with rising ctDNA who have not yet had rPD. Pts accrual and sample collection are ongoing, and additional data will be presented. Clinical trial information: NCT03702309.

4136 Background: Mesothelin (MSLN) is overexpressed in 80-85% of pancreatic adenocarcinomas (PDAC). Anetumab ravtansine (AR) is a fully human anti-MSLN immunoglobulin G1 antibody conjugated to the anti-tubulin maytansinoid DM4. Through NCI-ETCTN, the North American Star Consortium conducted a phase I study to evaluate the safety/tolerability of AR in various combinations in patients (pts) with PDAC. Here, we report preliminary results of the escalation part. Methods: Pts with advanced PDAC after at least one line of treatment were included. AR was combined with nivolumab (ARM1), nivolumab/ipilimumab (ARM 2), or nivolumab plus gemcitabine (Gem) (ARM3), using an integrated biomarker analysis. Two dose levels (DL) of AR were evaluated, DL1=5.5mg/kg and DL2=6.5mg/kg (established RP2D). Key eligibility criterion was MSLN expression in >5% of tumor cells by immunohistochemistry. Pts with prior anti-PD1/anti-CTLA4 treatment were excluded but treatment with prior Gem was allowed. Mandatory blood and paired tumor samples were collected for investigation of the immune microenvironment, genomic/transcriptomic changes and for an in-depth description of AR pharmacokinetics. Results: Data cut-off date was 22/01/2022. A total of n=33 pts were enrolled, n=11 (ARM 1), n=13 (ARM 2) and n=9 (ARM3). Median age of pts was 66 (40-83), 33% of PS=0 and 66% of PS=1. Twenty-six pts (79%) had previously been exposed to Gem. Median number of prior lines of treatment was 3 (1-7). Twenty-eight patients were evaluable for DLT. Grade (G)3/4 TRAEs: 0% in ARM1DL1, 5.3% in ARM1DL2, 0% in ARM2DL1, 16.9% in ARM2DL2, 8.6% in ARM3DL1 and 19.5% in ARM3DL2. There were 2 dose-limiting toxicities in ARM2DL2, one G3 upper gastrointestinal haemorrhage, possibly related to AR, and one G3 thrombocytopenia and G3 anaemia, definitely related to AR. Ocular toxicity events were G1/2 blurred vision in 5/33 (15%) and G1 xerophthalmia in 1/33 (3%), related to both AR and anti-PD1; G2 keratitis in 1/33 (3%), related to AR only. Only G1 peripheral neuropathy was observed in 4/33 (12%) pts. Efficacy data is presented in the table. In ARM3, the range of tumor measurement (ΤΜ) change was ΔTM=–16.8% to +16.2% and 3/8 (36%) pts with SD had previously been exposed to Gem. Conclusions: Based on the observed disease control rate and acceptable toleratbility, ARM3 (both DL1 and DL2) will be tested in the expansion part. A further 20 patients will be recruited for dose confirmation and comprehensive biomarker evaluation. Pharmacokinetic/pharmacodynamic analysis is under way. Clinical trial information: NCT03816358. [Table: see text]

Ovarian high-grade serous carcinoma (HGSC) prognosis correlates directly with presence of intratumoral lymphocytes. However, cancer immunotherapy has yet to achieve meaningful survival benefit in patients with HGSC. Epigenetic silencing of immunostimulatory genes is implicated in immune evasion in HGSC and re-expression of these genes could promote tumour immune clearance. We discovered that simultaneous inhibition of the histone methyltransferases G9A and EZH2 activates the CXCL10-CXCR3 axis and increases homing of intratumoral effector lymphocytes and natural killer cells whilst suppressing tumour-promoting FoxP3+ CD4 T cells. The dual G9A/EZH2 inhibitor HKMTI-1-005 induced chromatin changes that resulted in the transcriptional activation of immunostimulatory gene networks, including the re-expression of elements of the ERV-K endogenous retroviral family. Importantly, treatment with HKMTI-1-005 improved the survival of mice bearing Trp53-/-null ID8 ovarian tumours and resulted in tumour burden reduction.These results indicate that inhibiting G9A and EZH2 in ovarian cancer alters the immune microenvironment and reduces tumour growth and therefore positions dual inhibition of G9A/EZH2 as a strategy for clinical development.Abstract Figure

ObjectivesTo describe the clinical activity of metronomic cyclophosphamide in a population of patients with recurrent ovarian cancer, and to identify predictors of clinical response.MethodsWe retrospectively reviewed all patients treated at our institution with oral metronomic cyclophosphamide for relapsed ovarian cancer between January 2012 and December 2016. These were identified from electronic chemotherapy prescription records. The primary endpoint was response rate by combined Gynecologic Cancer InterGroup (GCIG) criteria. Data on patient demographics, previous therapies, platinum resistance, germline BRCA1/2 (gBRCA1/2) status, disease response by radiological or cancer antigen 125 (CA125) criteria alone, adverse events secondary to metronomic cyclophosphamide treatment, progression-free survival, and overall survival were also evaluated.Results50 out of 68 patients treated with oral metronomic cyclophosphamide were evaluable for disease response. By combination criteria (radiological plus CA125), complete response was 0%, partial response 32%, stable disease 16%, and progressive disease 52%. In the intention-to-treat population (n=68), progression-free survival and overall survival were 2.6 months and 6 months, respectively. Having a gBRCA1/2 mutation reduced the risk of disease progression by radiological criteria (OR 0.07, 95% CI 0.008 to 0.67, p=0.02), and patients with gBRCA1/2 mutations had improved progression-free survival (7.9 vs 2.5 months, HR 0.4, 95% CI 0.23 to 0.74, p=0.003) and overall survival (15.5 vs 6 months, HR 0.49, 95% CI 0.28 to 0.85, p=0.02) with metronomic cyclophosphamide when compared with patients without gBRCA1/2 mutations (or unknown gBRCA1/2 status).ConclusionOral metronomic cyclophosphamide showed a clinical benefit in 48% of patients with recurrent ovarian cancer. gBRCA1/2 status can be an independent predictor of response.

Oncolytic viruses (OVs) can trigger profound innate and adaptive immune responses, which have the potential both to potentiate and reduce the activity of OVs. Natural killer (NK) cells can mediate potent anti-viral and anti-tumoral responses, but there are no data on the role of NK cells in oncolytic adenovirus activity. Here, we have used two different oncolytic adenoviruses—the Ad5 E1A CR2-deletion mutant dl922-947 (group C) and the chimeric Ad3/Ad11p mutant enadenotucirev (group B)—to investigate the effect of NK cells on overall anti-cancer efficacy in ovarian cancer. Because human adenoviruses do not replicate in murine cells, we utilized primary human NK cells from peripheral blood and ovarian cancer ascites. Our results show that dl922-947 and enadenotucirev do not infect NK cells, but induce contact-dependent activation and anti-cancer cytotoxicity against adenovirus-infected ovarian cancer cells. Moreover, manipulation of NK receptors DNAM-1 (DNAX accessory molecule-1) and TIGIT (T cell immunoreceptor with Ig and ITIM domains) significantly influences NK cytotoxicity against adenovirus-infected cells. Together, these results indicate that NK cells act to increase the activity of oncolytic adenovirus in ovarian cancer and suggest that strategies to augment NK activity further via the blockade of inhibitory NK receptor TIGIT could enhance therapeutic potential of OVs. Keywords: Ovarian cancer, Oncolytic virus, Adenovirus, NK cell, DNAM-1, TIGIT

333 Background: Patients (pts) diagnosed with metastatic renal cell carcinoma (mRCC) with rhabdoid differentiation (RD) have a poor prognosis due to aggressive tumor behavior and inherent treatment resistance to targeted therapies. However, recent data has demonstrated the survival benefit of immunotherapy (IO) in mRCC. Here, we report survival outcomes of pts with mRCC with RD treated with targeted therapy and or IO. Methods: This retrospective survival analysis was performed in pts with mRCC and RD treated with targeted treatment and IO at Princess Margaret Cancer Centre (PM), Toronto. Demographics, disease characteristics and survival outcomes were collected. Overall survival (OS) was calculated using the Kaplan-Meier method (log-rank). OS hazard ratio (HR) were calculated using cox proportional hazards model. IBM SPSS Statistics v26 was used to conduct statistical analyses. Results: We identified 474 pts diagnosed with mRCC at PM between 2002 and 2019. A total of 57 (12%) pts diagnosed with mRCC had RD and were treated with targeted and or IO agents. Of these, 42 (73.7%) pts had pure RD and 15 (26.3%) pts had mixed RD and sarcomatoid features. Median age was 62 yrs (35-86yrs) and 42 (73.7%) were male. Overall, as per the IMDC score, 5(8.8%), 27(47.4%) and 25(43.8%) pts were categorized as good, intermediate, and poor risk, respectively. In total, 34 (59.6%) pts were treated with targeted therapy only during their first and second line treatment course and 23 (40.4%) pts received IO alone or in combination with targeted treatment in the first or second line. With a median follow up of 53.4 months (range, 38.3-68.4 months), the median OS for the whole mRCC with RD cohort was 23.1 months (95% CI: 14.6-31.5). The median OS in all pts treated with targeted therapy only vs IO receipt was 13.1 months (95%CI: 5.4-20.8 months) vs not reached; p = 0.026, respectively. HR for OS was 0.44 (95%CI: 0.22-0.93; p = 0.03) favoring IO receipt. Conclusions: While the number of pts included in our retrospective review was small, our analysis has suggested that pts with mRCC and RD have poor survival outcomes that may be improved with IO treatment. RD is a histopathological feature that could identify pts who may benefit from IO therapy. Further analysis is needed to explore the impact of RD on IO treatment response.

345 Background: Patients (pts) with metastatic renal cell carcinoma (mRCC) and tumor thrombus have historically been treated with cytoreductive nephrectomy (CN), however, their outcomes remain poor. Recent phase III data suggest the role for cytoreductive nephrectomy (CN) in mRCC is limited. To date, only case-reports have described thrombus response to systemic therapy. Here, we describe response and survival outcomes of de novo mRCC patients with thrombi treated with systemic therapy with or without CN. Methods: Pts with de novo mRCC at the Princess Margaret Cancer Centre were identified. Demographics, disease characteristics (including the presence of thrombus) and survival outcomes were collected. Progression free survival (PFS) and overall survival (OS) in months (m) was calculated using the Kaplan-Meier method (log-rank). Results: We identified 226 pts with de novo mRCC between 2002 and 2019. Pt demographics are listed in the table. In total, 157 pts underwent a CN and 69 received only systemic therapy. Of the total cohort, 64 pts (28%) had tumor thrombus at presentation (46 CN, 18 no CN). Of the 18 patients with tumor thrombus treated with only systemic therapy, 17 received first-line angiogenesis inhibitors and 1 had chemotherapy (medullary histology). Six (33%) had thrombus progression, 8 (44%) had stable disease and four (22%) had an objective response. Median PFS and OS for patients with and without tumor thrombus treated with systemic therapy only was not significantly different [5.3m (95% CI 3.6-11.7) vs 4.1m (95% CI 3.1-5.9)), p=0.33; OS: 12.1m (95% CI 8.8-27.7) vs 13.9m (95% CI 7.9-21.5), p=0.87). PFS for patients with tumor thrombus who had CN was similar to those treated with systemic therapy alone [8.4m (95% CI: 5.7-13.4) vs 5.3m (95% CI 3.6-11.7), p=0.57] but OS was significantly better favoring CN [29.4m (95% CI: 17.4-48.9) vs 12.1m (95% CI 8.8-27.7), p=0.01). Conclusions: In this largest series of patients with mRCC and thrombus treated with systemic therapy +/- CN, CN appears to plays an important role. More data is needed for patients with tumor thrombus treated with immunotherapy to confirm these findings and elucidate the role of surgery in those cohorts. Bias due to the retrospective study design is an important limitation.[Table: see text]

Background Epertinib (S-222611) is a potent reversible inhibitor of HER2, EGFR and HER4. This trial evaluated the safety, tolerability, pharmacokinetics and antitumour activity of daily oral epertinib combined with trastuzumab (arm A), with trastuzumab plus vinorelbine (arm B) or with trastuzumab plus capecitabine (arm C), in patients with HER2-positive metastatic breast cancer (MBC). Methods Eligible patients, with or without brain metastases, had received prior HER2-directed therapy. A dose-escalation phase determined the tolerability of each combination and established a dose for further study. Further, patients were recruited to expansion cohorts in each of the 3 arms to further explore efficacy and safety. Results The recommended doses of epertinib were 600 mg, 200 mg and 400 mg in arms A, B and C, respectively. The most frequent grade 3/4 adverse event (AE) was diarrhoea in all arms, which was manageable with medical intervention and dose modification. The objective response rate (complete response [CR] plus partial response [PR]) in heavily pre-treated HER2-positive MBC patients at the recommended doses of epertinib combined with trastuzumab was 67% (N = 9), with trastuzumab plus vinorelbine was 0% (N = 5) and with trastuzumab plus capecitabine was 56% (N = 9). Notably, 4 of 6 patients previously treated with T-DM1 responded in the arm A expansion cohort (epertinib plus trastuzumab). In the arm C expansion cohort (epertinib plus trastuzumab plus capecitabine), 4 of 7 patients responded despite previous exposure to capecitabine. Measurable regression of brain metastases was observed in patients with CNS target lesions treated in both arms A and C. Conclusion We observed safety, tolerability and encouraging antitumour activity of epertinib combined with trastuzumab, or with trastuzumab plus capecitabine. This supports further evaluation of these combinations in patients with pre-treated HER2-positive MBC, with or without brain metastases. Trial registration EudraCT Number: 2013-003894-87; registered 09-September-2013.

To determine the rates of germline BRCA1 and BRCA2 mutations in Scottish patients with ovarian cancer, before and after a change in testing policy.Retrospective cohort study.Four cancer/genetics centres in Scotland.Patients with ovarian cancer undergoing germline BRCA1 and BRCA2 (gBRCA1/2) sequencing before 2013 (under the 'old criteria', with selection based solely on family history), after 2013 (under the 'new criteria', with sequencing offered to newly presenting patients with non-mucinous ovarian cancer), and in the 'prevalent population' (who presented before 2013, but were not eligible for sequencing under the old criteria but were sequenced under the new criteria).Clinicopathological and sequence data were collected before and for 18 months after this change in selection criteria.Frequency of germline BRCA1, BRCA2, RAD51C, and RAD51D mutations.Of 599 patients sequenced, 205, 236, and 158 were in the 'old criteria', 'new criteria', and 'prevalent' populations, respectively. The frequency of gBRCA1/2 mutations was 30.7, 13.1, and 12.7%, respectively. The annual rate of gBRCA1/2 mutation detection was 4.2 before and 20.7 after the policy change. A total of 48% (15/31) 'new criteria' patients with gBRCA1/2 mutations had a Manchester score of15 and would not have been offered sequencing based on family history criteria. In addition, 20 patients with gBRCA1/2 were identified in the prevalent population. The prevalence of gBRCA1/2 mutations in patients aged70 years was 8.2%.Sequencing all patients with non-mucinous ovarian cancer gives a much higher annual gBRCA1/2 mutation detection rate, with the frequency of positive tests still exceeding the 10% threshold upon which many family history-based models operate.BRCA sequencing all non-mucinous cancer patients increases mutation detection five fold.

Summary Background Few effective treatments exist for patients with advanced urothelial carcinoma that has progressed after platinum-based chemotherapy. We assessed the activity and safety of nivolumab in patients with locally advanced or metastatic urothelial carcinoma whose disease progressed after previous platinum-based chemotherapy. Methods In this phase 1/2, multicentre, open-label study, we enrolled patients (age ≥18 years) with urothelial carcinoma of the renal pelvis, ureter, bladder, or urethra at 16 sites in Finland, Germany, Spain, the UK, and the USA. Patients were not selected by PD-L1 expression, but tumour PD-L1 membrane expression was assessed retrospectively. Patients received nivolumab 3 mg/kg intravenously every 2 weeks until disease progression or treatment discontinuation because of unacceptable toxicity or other protocol-defined reasons, whichever occurred later. The primary endpoint was objective response by investigator assessment. All patients who received at least one dose of the study drug were included in the analyses. We report an interim analysis of this ongoing trial. CheckMate 032 is registered with ClinicalTrials.gov, NCT01928394. Findings Between June 5, 2014, and April 24, 2015, 86 patients with metastatic urothelial carcinoma were enrolled in the nivolumab monotherapy group and 78 received at least one dose of treatment. At data cutoff (March 24, 2016), the minimum follow-up was 9 months (median 15·2 months, IQR 12·9–16·8). A confirmed investigator-assessed objective response was achieved in 19 (24·4%, 95% CI 15·3–35·4) of 78 patients. Grade 3–4 treatment-related adverse events occurred in 17 (22%) of 78 patients; the most common were elevated lipase (four [5%]), elevated amylase (three [4%]), and fatigue, maculopapular rash, dyspnoea, decreased lymphocyte count, and decreased neutrophil count (two [3%] each). Serious adverse events were reported in 36 (46%) of 78 patients and eight (10%) had a serious adverse event judged to be treatment related. Two (3%) of 78 patients discontinued because of treatment-related adverse events (grade 4 pneumonitis and grade 4 thrombocytopenia) and subsequently died. Interpretation Nivolumab monotherapy was associated with a substantial and durable clinical response and a manageable safety profile in previously treated patients with locally advanced or metastatic urothelial carcinoma. These data support further investigation of nivolumab monotherapy in advanced urothelial carcinoma. Funding Bristol-Myers Squibb.

Large-scale epidemiological studies have shown that the incidence of second primary thyroid cancer in subjects diagnosed and treated for testicular cancer is raised. This finding is strongly associated to treatment with radiotherapy and/or chemotherapy and it is explained by their mutagenic effect. On the other hand, inherited cancer susceptibility syndromes inducing both testicular and thyroid cancers denote that these tumours might share common genomic aberrations. We herein present our experience with three cases of metachronous development of thyroid cancer after diagnosis and treatment of testicular cancer in our tertiary cancer centre. Our case report contributes to the limited available literature on such findings and aims to raise awareness of the cancer physicians treating these particular tumour types.

Background: Ovarian high-grade serous carcinoma (HGSC) remains a poor prognosis disease due to its late presentation and lack of “actionable” mutations to target pharmacologically. The host immune system, however, plays a pivotal role with the presence of cytotoxic T lymphocytes and chemokines that regulate T-cell trafficking both having positive effect on survival in preclinical and clinical studies. HGSC cells can achieve immune escape via epigenetic silencing of key immune-related genes, including via DNA methylation; when DNA methylation is pharmacologically reversed, genes involved in antigen presentation, receptor-dependent immune cell stimulation, and chemokine release are reactivated. One of these genes encodes the angiostatic chemokine Cxcl10, which is a T-lymphocyte attractant. In order to elucidate other potential epigenetic mechanisms directly or indirectly involved in Cxcl10 gene silencing, we will screen a library of novel epigenetic probes that target bromodomains, methyltransferases, demethylases, and others epigenetic pathways (Structural Genomic Consortium library). Aims: We will use Trp53-/- ID8 ovarian cancer cells to perform a medium-throughput screening of 40 novel epigenetic probes, measuring cxcl10 production, with the demethylating drug decitabine as positive control. Methods: Trp53-/- ID8 cells were treated with decitabine for up to 72 hours. Cell-cycle analysis was assessed via BrdU incorporation assay. Cytokine/chemokine transcription was assessed using RT2 profiler 84 gene chemo/cytokine PCR array (Qiagen), and verified using qRT-PCR. Acid-hydrolysed DNA was subjected to mass spectrometry/liquid chromatography to quantify the mean ratio of methyl-cytosine/cytosine. Western immunoblotting was performed to test DNMT1 protein levels in protein lysates after decitabine treatment. Cxcl10 levels in supernatant were quantified by ELISA. Results: Treatment of Trp53-/- ID8 cells with decitabine (DAC), at non-cytostatic/cytotoxic doses causes upregulation of multiple chemokines, specifically Cxcl10. 200nM DAC for 48 hours increased Cxcl10 transcription 22-fold (95% CI 20.6-21.1-fold, p=0.0001, values normalized to Gapdh control), and protein levels in supernatant three-fold (t test p Conclusions: Abrogation of DNA methylation with DAC in Trp53-/- ID8 cells induces an increase in the chemokine cxcl10, at both transcriptional and protein level. This provides a robust control for a medium-throughput screening of other epigenetic modifiers that are still at an early drug development stage, such as probes against bromodomains, methyltransferases, and demethylases. Such screening can unmask novel epigenetic mechanisms involved in immune-related gene transcription and offer new ways to potentiate immunotherapy in ovarian cancer. Citation Format: Pavlina Spiliopoulou, Josephine Walton, Suzanne Dowson, Alex Binks, Oliver Maddocks, Peter Adams, Iain McNeish. Epigenetic modification of ovarian cancer immunogenicity. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr A37.

Background: Continuous, metronomic administration of the alkylating agent cyclophosphamide (MC) has antitumor activity that may depend upon antiangiogenic and immune-stimulatory effects. In retrospective, mainly single-center clinical studies, objective response rate is reported as 20-25% in solid tumors. Its DNA-damaging potential could be potentiated in patients with BRCA-deficient tumors, a relatively common occurrence is ovarian cancer (OC). Here, we present efficacy and toxicity data of MC in patients with recurrent OC. We also investigate the influence of germline BRCA1/2 mutation status on outcome. Methods: Patient records at a large regional UK cancer center were retrospectively reviewed. BRCA status was tested using Sanger sequencing, Gehan-Breslow-Wilcoxon and Fisher’s exact test for statistical analysis. Results: Between 2012-2016, forty-nine patients with recurrent OC, median age 68 years (range 44-86), received 2 cycles of MC. Starting dose was 50mg/day in 45 patients and 100mg/day in 4 patients. Forty patients (82%) had acquired platinum-resistant disease. Ninety-two percent (92%) of patients had received 2 lines of previous treatment (median=3, range 1-10 lines). Main toxicities were myelotoxicity (37% Grade 1-2) and gastrointestinal adverse events (20% Grade 1-2). There was 1 case of Grade 3 myelotoxicity and 1 case of Grade 3 transaminitis. There were no treatment-related deaths. Median number of cycles was 3 (range 2-16 cycles). Eighteen patients (37%) showed a CA125 response. Radiologic responses were seen in 3/42 (7.1%) evaluable patients; 12/42 (28.6%) showed stable disease (SD). Median progression-free survival (PFS) and overall survival (OS) were 2.9 and 9 months, respectively. The rate of disease stabilization (PR or SD or Ca125 response) beyond 4 months was 18/49 (36.7%). PFS for this patient group achieving stable disease was 7.2 months. Germline BRCA status was known for 35/49 patients. Patients with germline BRCA1/2 mutations had improved radiologic responses compared to wild-type patients (33% vs 0%; p=0.0128), longer PFS (8.3m vs 2.5m, p=0.013) and a trend towards longer OS (16m vs 6m, p=0.10). Conclusions: Metronomic cyclophosphamide has overall modest activity in recurrent, platinum-resistant OC. However, it can achieve meaningful disease stabilization for some patients and offer a safe and easy to administer treatment in heavily pretreated cases. Patients with germline BRCA1/2 mutations have improved response rate and progression-free survival. Within the limitations of this small study, cyclophosphamide could be considered an option for this subset of patients. Citation Format: Pavlina Spiliopoulou, Ishtiaq Zubairi, Sarah Gibson, Jennifer Brown, Iain McNeish, Ros Glasspool. Influence of germline BRCA mutation on response to oral cyclophosphamide in relapsed heavily pretreated ovarian cancer. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B02.

414 Background: Nivolumab has shown efficacy and acceptable safety in 2 open-label, multicenter studies (CheckMate 032 and 275) and is approved for patients (pts) with metastatic urothelial carcinoma (mUC) after ≥1 platinum-based therapy. Here we report longer-term efficacy and safety results for pts with mUC in the phase 1/2 CheckMate 032 study who received nivolumab monotherapy based on > 2 years of follow-up. Methods: Pts with mUC, regardless of programmed death-1 ligand 1 (PD-L1) expression status, received nivolumab 3 mg/kg intravenously every 2 weeks until progression or discontinuation. Tumor PD-L1 membrane expression was assessed with Dako PD-L1 immunohistochemical staining. Primary endpoint: objective response rate (ORR; RECIST 1.1); other endpoints: safety, progression-free survival (PFS), overall survival (OS), and duration of response. Results: Of 78 treated pts (median age 65.5 years; range, 31-85), 52 (66.7%) had received ≥2 prior therapies. At a minimum follow-up of 24 months, 11 pts (14.1%) remain on treatment. Treatment discontinuation was mainly due to disease progression (52 pts [66.7%]). Tumor PD-L1 expression was evaluable in 68 pts (87.2%); 26 (38.2%) pts had ≥1% and 42 (61.8%) had < 1% expression. The table shows overall efficacy. Updated ORR was 25.6%, with 1 additional complete response (CR) achieved for a CR rate of 8%. Median duration of response was not reached. ORR, 1- and 2-year PFS and OS rates were similar between the PD-L1 < 1% and > 1% subsets. Grade 3 or 4 treatment-related adverse events (TRAEs) occurred in 22 pts (28.2%); most frequent were ↑lipase (6.4%), ↑amylase (5.1%), and maculopapular rash (3.8%). One pt had a grade 5 TRAE (pneumonitis). Conclusions: Nivolumab showed clinically meaningful, durable efficacy with promising long-term survival regardless of PD-L1 expression, and no new toxicity signals with longer-term follow-up in previously treated pts with mUC. Clinical trial information: NCT01928394. [Table: see text]

Until recently, treatment for metastatic melanoma was characterised by a limited availability of treatment options that offer objective survival benefit. Cytotoxic agents fundamentally lack the ability to achieve disease control and cytokine therapy with interleukin-2 has an unacceptably high – for the use across all patient cohorts – rate of toxicities. The validation of braf as an oncogene driving melanoma tumorigenesis, as well as the discovery of the role of CTLA-4 receptor in the evasion of anticancer immune response by melanoma, has revolutionised our treatment options against a disease with dismal prognosis. Quick implementation of translational discoveries brought about BRAF/MEK inhibition in clinic, while at the same time, wider experience with CTLA-4 blockade enabled clinicians to manage previously fatal immune-related toxicities with greater confidence. The suitability for clinical use of other oncogenic drivers such as NRAS and c-kit is currently being tested whilst the PD-1/PD-L1/PD-L2 axis has emerged as a new immunotherapy target with exciting early phase results. The recent exponential progress in treatment of melanoma has set an example of translational medicine and the current review aims to explain why, as well as suggesting new goals for the future.

The therapeutic landscape of metastatic colorectal cancer (mCRC) has changed substantially with the emergence of new molecularly targeted agents (MTA) used as single agents or alongside standard chemotherapy. The use of these MTAs extended the overall survival of patients with mCRC to a level that current chemotherapeutics alone could not achieve. In addition, improvement in surgical techniques and ablation modalities offer cure to a limited subset of patients with mCRC and MTAs have been found to have a significant role here too, as they aid resectability. However, for the majority of patients, mCRC remains an invariably incurable disease necessitating continued courses of combined treatment modalities. During the course of these treatments, either cytotoxic or biological, cancer cells maintain their ability to acquire mitogenic mutations which render them resistant to treatment. Key challenges remain to identify appropriate subsets of patients who will most likely benefit from these new MTAs and effectively select these based on validated biomarkers. Moreover, better knowledge of the biology of colorectal cancer and the mechanisms via which it bypasses blockade of known signalling pathways will help us design better and more rational sequencing of these treatments, so that we can maximise the survivorship of mCRC patients. This review outlines treatment strategies for known molecular alterations with new MTAs and highlights some promising strategies.

e22512Background: Imatinib is the treatment of choice for GIST. Previous studies suggest that trough concentration (Cmin) of more than 1.1mg/L achieve better outcomes and that Cmin correlates with ...

4521Background: gemcitabine (G) plus cisplatin (C) is a standard-of-care, combination chemotherapy regimen for patients (pts) with bladder cancer (BC), in both neoadjuvant and palliative settings. ...

4501Background: Minimal antitumor activity of existing therapies and the observation of immune dysfunction in bladder cancer have prompted evaluation of immunotherapy in this malignancy. Nivolumab (fully human IgG4 programmed death-1 immune checkpoint inhibitor antibody) monotherapy has shown survival benefit in patients (pts) with melanoma, lung cancer, and renal cell carcinoma. Here, we report efficacy and safety of nivolumab monotherapy in pts with mUC after ≥1 prior line of platinum-based therapy in an open-label, multicenter phase I/II study (NCT01928394). Methods: Pts (unselected by PD-L1 expression status) with mUC received nivolumab 3 mg/kg intravenously every 2 weeks until progression or discontinuation. Primary endpoint was objective response rate (ORR; RECIST 1.1). Other endpoints included safety, duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Results: Of 78 treated pts (median age 65.5 years; range, 31–85), 65.4% had received ≥2 prior therapies. At a me...

e16532 Background: Germline mutations in BRCA1/2 (gBRCA) are strongly linked to the development of non-mucinous ovarian cancer (OC), in particular high grade serous OC (HGSOC). Up to 18% unselected...