TROPHY-U-01, a phase II open-label study of sacituzumab govitecan in patients with metastatic urothelial carcinoma progressing after platinum-based chemotherapy and checkpoint inhibitors: updated safety and efficacy outcomes.

BACKGROUND: Sacituzumab govitecan (SG) is a Trop-2-directed antibody-drug conjugate containing cytotoxic SN-38, the active metabolite of irinotecan. SG received accelerated US Food and Drug Administration approval for locally advanced (LA) or metastatic urothelial carcinoma (mUC) previously treated with platinum-based chemotherapy and a checkpoint inhibitor, based on cohort 1 of the TROPHY-U-01 study. Mutations in the uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene are associated with increased adverse events (AEs) with irinotecan-based therapies. Whether UGT1A1 status could impact SG toxicity and efficacy remains unclear. PATIENTS AND METHODS: TROPHY-U-01 (NCT03547973) is a multicohort, open-label, phase II registrational study. Cohort 1 includes patients with LA or mUC who progressed after platinum- and checkpoint inhibitor-based therapies. SG was administered at 10 mg/kg intravenously on days 1 and 8 of 21-day cycles. The primary endpoint was objective response rate (ORR) per central review; secondary endpoints included progression-free survival, overall survival, and safety. Post hoc safety analyses were exploratory with descriptive statistics. Updated analyses include longer follow-up. RESULTS: Cohort 1 included 113 patients. At a median follow-up of 10.5 months, ORR was 28% (95% CI 20.2% to 37.6%). Median progression-free survival and overall survival were 5.4 months (95% CI 3.5-6.9 months) and 10.9 months (95% CI 8.9-13.8 months), respectively. Occurrence of grade ≥3 treatment-related AEs and treatment-related discontinuation were consistent with prior reports. UGT1A1 status was wildtype (∗1|∗1) in 40%, heterozygous (∗1|∗28) in 42%, homozygous (∗28|∗28) in 12%, and missing in 6% of patients. In patients with ∗1|∗1, ∗1|∗28, and ∗28|∗28 genotypes, any grade treatment-related AEs occurred in 93%, 94%, and 100% of patients, respectively, and were managed similarly regardless of UGT1A1 status. CONCLUSIONS: With longer follow-up, the ORR remains high in patients with heavily pretreated LA or mUC. Safety data were consistent with the known SG toxicity profile. AE incidence varied across UGT1A1 subgroups; however, discontinuation rates remained relatively low for all groups.

Folate hydrolase-1 (FOLH1) is a novel target for antibody-based brachytherapy in Merkel cell carcinoma.

BACKGROUNDS: Folate Hydrolase-1 (FOLH1; PSMA) is a type II transmembrane protein, luminally expressed by solid tumour neo-vasculature. Monoclonal antibody (mAb), J591, is a vehicle for mAb-based brachytherapy in FOLH1+ cancers. Brachytherapy is a form of radiotherapy that involves placing a radioactive material a short distance from the target tissue (e.g., on the skin or internally); brachytherapy is commonly accomplished with the use of catheters, needles, metal seeds and antibody or small peptide conjugates. Herein, FOLH1 expression in primary (p) and metastatic (m) Merkel cell carcinoma (MCC) is characterized to determine its targeting potential for J591-brachytherapy. MATERIALS & METHODS: Paraffin sections from pMCC and mMCC were evaluated by immunohistochemistry for FOLH1. Monte Carlo simulation was performed using the physical properties of conjugated radioisotope lutetium-177. Kaplan-Meier survival curves were calculated based on patient outcome data and FOLH1 expression. RESULTS: Eighty-one MCC tumours were evaluated. 67% (54/81) of all cases, 77% (24/31) pMCC and 60% (30/50) mMCC tumours were FOLH1+. Monte Carlo simulation showed highly localized ionizing tracks of electrons emitted from the targeted neo-vessel. 42% (34/81) of patients with FOLH1+/- MCC had available survival data f or analysis. No significant differences in our limited data set were detected based on FOLH1 status (p = 0.4718; p = 0.6470), staining intensity score (p = 0.6966; p = 0.9841) or by grouping staining intensity scores (- and + vs. ++, +++, +++) (p = 0.8022; p = 0.8496) for MCC-specific survival or recurrence free survival, respectively. CONCLUSIONS: We report the first evidence of prevalent FOLH1 expression within MCC-associated neo-vessels, in 60-77% of patients in a large MCC cohort. Given this data, and the need for alternatives to immune therapies it is appropriate to explore the safety and efficacy o f FOLH1-targeted brachytherapy for MCC.

Upper tract urothelial carcinoma topical issue 2016: treatment of metastatic cancer.

PURPOSE: To review the management of metastatic upper tract urothelial carcinoma (UTUC) including recent advances in targeted and immune therapies as an update to the 2014 joint international consultation on UTUC, co-sponsored by the Société Internationale d'Urologie and International Consultation on Urological Diseases. METHODS: A PubMed database search was performed between January 2013 and May 2016 related to the treatment of metastatic UTUC, and 54 studies were selected for inclusion. RESULTS: The management of patients with metastatic UTUC is primarily an extrapolation from evidence guiding the management of metastatic urothelial carcinoma of the bladder. The first-line therapy for metastatic UTUC is platinum-based combination chemotherapy. Standard second-line therapies are limited and ineffective. Patients with UTUC who progress following platinum-based chemotherapy are encouraged to participate in clinical trials. Recent advances in genomic profiling present exciting opportunities to guide the use of targeted therapy. Immunotherapy with checkpoint inhibitors has demonstrated extremely promising results. Retrospective studies provide support for post-chemotherapy surgery in appropriately selected patients. CONCLUSIONS: The management of metastatic UTUC requires a multi-disciplinary approach. New insights from genomic profiling using targeted therapies, novel immunotherapies, and surgery represent promising avenues for further therapeutic exploration.

OC-14 - Baseline D-dimer levels are predictive of recurrent venous thromboembolism (VTE) at 6 months in cancer patients with VTE treated with tinzaparin.

INTRODUCTION: VTE is a major complication in cancer patients. Despite treatment with low molecular weight heparin (LMWH), 9% will have recurrent VTE within 6 months. Measurement of plasma biomarkers in cancer patients receiving LMWH may be predictive of recurrent VTE or overall survival (OS). AIM: We conducted a single arm phase 2 study to evaluate the efficacy and safety of once daily tinzaparin for the initial treatment and extended prophylaxis of VTE in cancer patients. The study included a prospective analysis of plasma biomarkers D-dimer and IL-6 to assess whether these were predictive of recurrent VTE or OS. MATERIALS AND METHODS: Consecutive patients with active cancer diagnosed with a pulmonary embolism (PE) and/or proximal deep venous thrombosis (DVT) at the University of Southern California Norris Comprehensive Cancer Center, Los Angeles County Medical Center, or New York Presbyterian - Weill Cornell Medical Center were invited to participate in this study with a target enrollment of 100 patients. Key eligibility criteria included: age ≥18, ECOG score ≤2, adequate organ function, and ≥6 month estimated survival. Patients were treated with daily subcutaneously tinzaparin 175 U/kg for 6 months on study. Tinzaparin could be continued ≤1 year at the discretion of the treating physician. All patients who received ≥1 dose were evaluable for efficacy and safety. Primary study endpoints were recurrent VTE or major bleeding. Secondary outcome measures included OS and plasma biomarkers. Biomarkers were measured at baseline, 7 days, 1 month and 6 months after tinzaparin initiation. Patients who had baseline and 1 week or 1 month samples collected were included in the biomarker analysis. RESULTS: 97 patients were enrolled. 2 patients were ineligible. 8 patients did not have baseline or follow-up biomarkers completed. 87 patients were included in the analysis. 28 (32%) of patients completed≥6 months of tinzaparin. Major bleeding occurred in 2 patients. 11 patients had recurrent VTE at 6 months (3 PE, 7 DVT, 1 central venous thrombosis not associated with a catheter). Median baseline D-dimer level was 2759 ng/mL (range: 375-37,591). Median baseline IL-6 level was 9.4 pg/mL (range: 0.8-20.9). Baseline D-dimer>median was predictive of VTE recurrence at 6 months (p=.006). Baseline IL-6>median was not predictive of VTE recurrence at 6 months. Neither 1 month D-dimer or IL-6 levels were predictive of VTE recurrence at 6 months. D-dimer and IL-6 at baseline and at 1 month were not predictive of OS. CONCLUSIONS: In patients with active cancer and VTE treated with tinzaparin, baseline D-dimer levels above the median value were predictive of VTE recurrence at 6 months.

PO-43 - Differential coagulation factor expression in neuroendocrine prostate cancer (PC), metastatic castrate-resistant PC, and localized prostatic adenocarcinoma.

INTRODUCTION: Neuroendocrine prostate cancer (NEPC) is an aggressive late-stage variant of PC that is often androgen-receptor negative. Most clinicians believe the VTE rate with NEPC is higher than with standard metastatic castration-resistant PC (mCRPC), but NEPC tends to present with bulkier visceral disease and include platinum chemotherapy unlike standard PC. In many solid tumors, a more aggressive phenotype correlates with increased VTE risk and elevated expression of coagulation factors. We previously reported on the differential expression of thrombin and tissue factor (TF) in NEPC versus localized PC and benign prostate tissue with a small NEPC cohort (N=7), which showed overexpression of prothrombin and reduced expression of TF in NEPC. AIM: To compare the expression of coagulation factors of NEPC vs mCRPC (and localized PC control) in an expanded datase. MATERIALS AND METHODS: Fresh frozen tissue biopsies were collected and separated into three cohorts based on pathology: localized PC (N=68), standard mCRPC (N=32), and NEPC (N=21). RNA was isolated and next generation paired-end mRNA sequencing was performed on Illumina Sequencers. F2 Prothrombin (F2), tissue factor (F3), carboxypeptidase (CPB2), fibrinogen (FGG, FGA), PAR-1 (F2R), and PAR-2 (F2RL1) were compared by Wilcoxon tests. RESULTS: Prothrombin had significantly higher expression in NEPC versus standard mCRPC (p <0.001). NEPC trended towards higher expression of CPB2 (p=0.1) and lower expression of F3 (p=0.23) and F2RL1 (p=0.14) compared to mCRPC. Compared to localized PC, both types of advanced disease (NEPC and mCRPC) overexpressed F2, FGA, FGB, and CPB2 (p<0.001) and had decreased expression of F3 and F2RL1 (p <0.001). CONCLUSIONS: Prothrombin is reliably overexpressed in NEPC vs mCRPC and localized PC. Advanced disease (regardless of subtype) is associated with significantly higher expression of prothrombin, fibrinogen, and carboxypeptidase and lower expression of TF and PAR-2. It is possible that there may be PC-specific differences with aggressive disease associated with the thrombin axis vs the more common TF/PAR2 axis commonly seen in other advanced solid tumors. Further research is required to understand these differences in biology and resulting thrombotic and hemostatic outcomes.

Cytotoxic chemotherapy in the treatment of advanced renal cell carcinoma in the era of targeted therapy.

BACKGROUND: Renal cell carcinoma (RCC) is a heterogeneous disease with regards to histology, progression, and response to treatment. Cytotoxic chemotherapy has been extensively studied in metastatic RCC (mRCC). Responses in most studies are modest and the mechanisms of resistance remain poorly understood. Targeted therapies have significantly improved outcomes in mRCC; however, most patients eventually relapse and die of their disease. Early clinical data suggest that combinations of chemotherapy and targeted agents are clinically active and are well tolerated. METHODS: We reviewed the available literature for published clinical trials incorporating traditional chemotherapeutic agents in the treatment of mRCC. These papers were identified through a Medline search and were included if they employed at least one chemotherapeutic agent in the treatment of mRCC. The literature was also reviewed for information regarding mechanisms of chemotherapy resistance. RESULTS: The data regarding the use of cytotoxic chemotherapy in mRCC consist of small, non-randomized phase I and II studies. The major response proportions with single agent chemotherapies are low but combination regimens either with other cytotoxic agents, cytokines, or targeted agents have demonstrated moderate activity. Disparate trial designs and lack of head to head clinical trials make it difficult to compare the efficacy of chemotherapy with that of immunotherapy or targeted agents. Chemotherapy is particularly useful in patients with collecting duct histology and predominantly sarcomatoid differentiation. Chemotherapy resistance may be mediated by overexpression of p-glycoprotein efflux pumps and the dysregulation of the microtubule-hypoxia inducible factor signaling axis. CONCLUSIONS: The role of cytotoxic chemotherapy in the treatment for clear cell RCC remains poorly defined. Cytotoxic chemotherapy is considered a standard of care in patients with mRCC with predominantly sarcomatoid differentiation and collecting duct RCC variants (Motzer et al., 2014). Early trials combining chemotherapy with targeted therapies are generally well tolerated and show clinical activity. A better understanding of the biology of aggressive subsets of RCC and mechanisms of resistance will help elucidate the role of cytotoxic agents in the current treatment paradigm of RCC.

Risk stratification of pT1-3N0 patients after radical cystectomy for adjuvant chemotherapy counselling.

BACKGROUND: In pT1-T3N0 urothelial carcinoma of the bladder (UCB) patients, multi-modal therapy is inconsistently recommended. The aim of the study was to develop a prognostic tool to help decision-making regarding adjuvant therapy. METHODS: We included 2145 patients with pT1-3N0 UCB after radical cystectomy (RC), naive of neoadjuvant or adjuvant therapy. The cohort was randomly split into development cohort based on the US patients (n=1067) and validation cohort based on the Europe patients (n=1078). Predictive accuracy was quantified using the concordance index. RESULTS: With a median follow-up of 45 months, 5-year recurrence-free and cancer-specific survival estimates were 68% and 73%, respectively. pT-stage, ge, lymphovascular invasion, and positive margin were significantly associated with both disease recurrence and cancer-specific mortality (P-values ≤ 0.005). The accuracies of the multivariable models at 2, 5, and 7 years for predicting disease recurrence were 67.4%, 65%, and 64.4%, respectively. Accuracies at 2, 5, and 7 years for predicting cancer-specific mortality were 69.3%, 66.4%, and 65.5%, respectively. We developed competing-risk, conditional probability nomograms. External validation revealed minor overestimation. CONCLUSION: Despite RC, a significant number of patients with pT1-3N0 UCB experience disease recurrence and ultimately die of UCB. We developed and externally validated competing-risk, conditional probability post-RC nomograms for prediction of disease recurrence and cancer-specific mortality.