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External beam radiation therapy (EBRT) to oligometastases may improve outcomes in patients with oligometastatic hormone-sensitive prostate cancer (oHSPC). Follow-up on this cohort has been limited to5 years and prospective data on de novo patients with oHSPC are lacking. We reviewed the long-term outcomes of patients with oHSPC treated with EBRT and androgen deprivation therapy on a prospective trial.From 2006 to 2011, patients with oHSPC with 1 to 5 metastases received 36 weeks of androgen deprivation therapy (luteinizing hormone-releasing hormone agonist + bicalutamide) and up to 53 Gy to all visible metastases. When indicated, the primary tumor or prostate bed was treated with EBRT up to 78 or 66 Gy, respectively.Twenty-nine patients were treated: 15 de novo, 14 oligorecurrent, and 21 patients (72.4%) had bone metastases. Median number of metastases per patient was 1 (range, 1-5). EBRT was administered to 52 lesions (38 bone, 12 pelvic lymph nodes [LNs], 2 nonpelvic LNs) up to 53 Gy (range, 47-66). Median follow-up was 9.9 years (years; range, 0.2-14.4). Median overall survival was 9.7 years (95% confidence interval [CI], 5.8-not reached). Median progression-free survival was 1.9 years (95% CI, 1.6-2.2). Patients who presented with prostate cancer-defined de novo metastases had significantly improved (P = .04) median progression-free survival (2.0 years; 95% CI, 1.3-6.0) compared with oligorecurrent patients (1.8 years; 95% CI, 1.0-2.0). Patients who presented with LN-only metastases had numerically improved (P = .13) median PFS (5.8 years; 95% CI, 1.2-not reached) compared with patients with bony metastases (1.8 years; 95% CI, 1.3-2.0). At last follow-up, 17 patients (58.6%) had local control of all EBRT-treated metastases. The metastases that locally progressed had previously been controlled for median 3.5 years (range, 1.7-10.5).Our results compare favorably with other reported studies of patients with oHSPC and provide new insights into their long-term outcomes.

Neoantigens are critical targets of antitumor T-cell responses. The ATLAS bioassay was developed to identify neoantigens empirically by expressing each unique patient-specific tumor mutation individually in Escherichia coli, pulsing autologous dendritic cells in an ordered array, and testing the patient's T cells for recognition in an overnight assay. Profiling of T cells from patients with lung cancer revealed both stimulatory and inhibitory responses to individual neoantigens. In the murine B16F10 melanoma model, therapeutic immunization with ATLAS-identified stimulatory neoantigens protected animals, whereas immunization with peptides associated with inhibitory ATLAS responses resulted in accelerated tumor growth and abolished efficacy of an otherwise protective vaccine. A planned interim analysis of a clinical study testing a poly-ICLC adjuvanted personalized vaccine containing ATLAS-identified stimulatory neoantigens showed that it is well tolerated. In an adjuvant setting, immunized patients generated both CD4+ and CD8+ T-cell responses, with immune responses to 99% of the vaccinated peptide antigens.Significance:Predicting neoantigens in silico has progressed, but empirical testing shows that T-cell responses are more nuanced than straightforward MHC antigen recognition. The ATLAS bioassay screens tumor mutations to uncover preexisting, patient-relevant neoantigen T-cell responses and reveals a new class of putatively deleterious responses that could affect cancer immunotherapy design.This article is highlighted in the In This Issue feature, p. 521

Supplementary Table from An Empirical Antigen Selection Method Identifies Neoantigens That Either Elicit Broad Antitumor T-cell Responses or Drive Tumor Growth

Supplementary Figure from An Empirical Antigen Selection Method Identifies Neoantigens That Either Elicit Broad Antitumor T-cell Responses or Drive Tumor Growth

Purpose: Palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, blocks proliferation in a RB and cyclin D–dependent manner in preclinical prostate cancer models. We hypothesized that cotargeting androgen receptor and cell cycle with palbociclib would improve outcomes in patients with metastatic hormone-sensitive prostate cancer (mHSPC). Patients and Methods: A total of 60 patients with RB-intact mHSPC were randomized (1:2) to Arm 1: androgen deprivation (AD) or Arm 2: AD + palbociclib. Primary endpoint was PSA response rate (RR) after 28 weeks of therapy. Secondary endpoints included safety, PSA, and clinical progression-free survival (PFS), as well as PSA and radiographic RR. Tumors underwent exome sequencing when available. Circulating tumor cells (CTC) were enumerated at various timepoints. Results: A total of 72 patients with mHSPC underwent metastatic disease biopsy and 64 had adequate tissue for RB assessment. A total of 62 of 64 (97%) retained RB expression. A total of 60 patients initiated therapy (Arm 1: 20; Arm 2: 40). Neutropenia was the most common grade 3/4 adverse event in Arm 2. Eighty percent of patients (Arm 1: 16/20, Arm 2: 32/40; P = 0.87) met primary PSA endpoint ≤4 ng/mL at 28 weeks. PSA undetectable rate at 28 weeks was 50% and 43% in Arms 1 and 2, respectively (P = 0.5). Radiographic RR was 89% in both arms. Twelve-month biochemical PFS was 69% and 74% in Arms 1 and 2, respectively (P = 0.72). TP53 and PIK3 pathway mutations, 8q gains, and pretreatment CTCs were associated with reduced PSA PFS. Conclusions: Palbociclib did not impact outcome in RB-intact mHSPC. Pretreatment CTC, TP53 and PIK3 pathway mutations, and 8q gain were associated with poor outcome.

Neoantigens are critical targets of antitumor T-cell responses. The ATLAS bioassay was developed to identify neoantigens empirically by expressing each unique patient-specific tumor mutation individually in Escherichia coli, pulsing autologous dendritic cells in an ordered array, and testing the patient's T cells for recognition in an overnight assay. Profiling of T cells from patients with lung cancer revealed both stimulatory and inhibitory responses to individual neoantigens. In the murine B16F10 melanoma model, therapeutic immunization with ATLAS-identified stimulatory neoantigens protected animals, whereas immunization with peptides associated with inhibitory ATLAS responses resulted in accelerated tumor growth and abolished efficacy of an otherwise protective vaccine. A planned interim analysis of a clinical study testing a poly-ICLC adjuvanted personalized vaccine containing ATLAS-identified stimulatory neoantigens showed that it is well tolerated. In an adjuvant setting, immunized patients generated both CD4+ and CD8+ T-cell responses, with immune responses to 99% of the vaccinated peptide antigens. Significance: Predicting neoantigens in silico has progressed, but empirical testing shows that T-cell responses are more nuanced than straightforward MHC antigen recognition. The ATLAS bioassay screens tumor mutations to uncover preexisting, patient-relevant neoantigen T-cell responses and reveals a new class of putatively deleterious responses that could affect cancer immunotherapy design. This article is highlighted in the In This Issue feature, p. 521

Background: Until the advent of T cell check point inhibitors standard second-line therapy for patients with metastatic urothelial cancer (mUC) was undefined. Histone deacetylase inhibitors (HDACi) have anti-cancer activity in a variety of tumor models including modulation of apoptosis in bladder cancer cell lines. We evaluated the efficacy and toxicity of the HDACi vorinostat in patients with mUC failing first-line platinum-based therapy either in the adjuvant/neoadjuvant setting or for recurrent/advanced disease. Methods: Vorinostat was given orally 200 mg twice daily continuously until progression or unacceptable toxicity. The primary end point was RECIST response rate (RR); a RR > 20% was deemed interesting in a 2-stage design requiring one response in the first 12 patients to proceed to 2nd stage for a total of 37 subjects. CT or MRI scan imaging occurred every 6 weeks. Results: Fourteen patients were accrued characterized by: median age 66 years (43–84); Caucasian (79%); males (86%); and Karnofsky performance status ≥90 (50%). Accrual was terminated in the first stage as no responses were observed. Best response was stable disease (3 patients). Progression was observed in 8 patients. Two patients came off therapy prior to re-imaging and a 3rd patient died while on treatment and was not assessed for response. Median number of cycles was 2 (range 1–11). Median disease-free survival and overall survival times were 1.1 (0.8, 2.1) & 3.2 (2.1, 14.5) months, respectively. Toxicities were predominantly cytopenias and thrombocytopenic bleeding. Two pts. had grade 5 toxicity unlikely related to treatment. Two pts. had grade 4 and 6 had grade 3 toxicities observed. Two patients with stable disease remained on therapy for 6+ cycles. Conclusions: Vorinostat on this dose-schedule had limited efficacy and significant toxicity resulting in a unfavorable risk:benefit ratio in patients with mUC. NCT00363883.

348 Background: Prostate cancer (PCa) patients treated with androgen deprivation therapy (ADT) may experience major adverse cardiovascular events (MACE). It is unclear how much of MACE is caused by ADT itself. High cholesterol has been associated with lower MACE risk in older men, not on statin therapy. This study evaluates MACE risk after ADT initiation for patients with and without hypercholesterolemia using real-world data. Methods: US electronic medical records (2010-2020) of PCa patients (n=45,059) receiving LHRH agonist/antagonist injections were analyzed to calculate the risk of MACE since ADT initiation in patients with and without hypercholesterolemia. Hypercholesterolemia was defined as having taken hypercholesterolemia medication or diagnosis with hypercholesterolemia prior to the first MACE event after ADT start. Exclusion criteria included lack of ADT initiation date or MACE within six months prior to ADT initiation. MACE was defined as myocardial infarction, stroke, and death from any cause. Kaplan-Meier event-free survival curves and cox regression were used to compare MACE risk between patients with and without hypercholesterolemia. Results: The dataset contained 178,388 LHRH injection entries and 7,681 MACE. MACE risk was only 1.8% lower (19.0% vs 20.8%) after 4 years for patients with hypercholesterolemia compared to those without (across 10 years, unadjusted: HR=0.88, 95% CI [0.83, 0.92] and adjusted: HR=0.85, 95% CI [0.77, 0.94]). Conclusions: Patients with hypercholesterolemia appear to have slightly lower MACE rates. This may be due to the use of statins, which can reduce the incidence of CV events in a general population. Our analysis of data over the most recent decade from ~45,000 PCa patients is likely an accurate reflection of the real world. Clinicians should monitor PCa patients with underlying CV risk factors and help educate them on lifestyle changes that could impact treatment outcomes.

Purpose Conventional imaging rarely localizes the site(s) of prostate cancer recurrence in patients undergoing evaluation for salvage radiation therapy (sRT) after radical prostatectomy (RP). LOCATE (NCT02680041) was a prospective, multicenter study investigating the impact of 18F-fluciclovine positron emission tomography and computed tomography (PET/CT) on the management of patients with biochemical recurrence of prostate cancer after curative-intent radiation or RP and negative or equivocal conventional imaging. Our objective was to determine the impact of 18F-fluciclovine PET/CT on treatment decisions for men planning to undergo sRT for biochemical recurrence post-RP. Methods and Materials We conducted a subgroup analysis of post-RP patients enrolled in LOCATE who were planning to undergo sRT with or without hormonal therapy based on prescan documentation. 18F-Fluciclovine PET/CT was performed according to standardized procedures. The treatment plan postscan was compared with the prescan plan, and Fisher exact test was used to determine the impact of prescan prostate-specific antigen (PSA) and Gleason sum (GS) on positivity and anatomic patterns of uptake. Results A total of 114 patients (median prescan PSA 0.42 [interquartile range, 0.3-1.1] ng/mL) met selection criteria (54% of patients in LOCATE). Forty-eight (42%) had 18F-fluciclovine-avid lesions. Twelve patients (11%) had positive findings only in the prostate bed, 24 (21%) had positivity only in the pelvis (prostate bed or pelvic nodes), and 24 (21%) had extrapelvic findings. PSA >0.5 ng/mL and GS ≥8 were associated with a higher risk of extrapelvic positivity (P Postscan, 55 (48%) patients had a management change; 37 (32%) had a change in overall treatment approach (ie, omission of sRT); and 18 (16%) had sRT target modification. Conclusions 18F-Fluciclovine PET/CT is positive in nearly half of patients planning to undergo post-RP sRT with negative/equivocal conventional imaging, with findings frequently leading to changes in management. PSA >0.5 ng/mL and GS ≥8 are associated with a higher risk of extrapelvic positive findings.

BackgroundGEN-009 adjuvanted personalized cancer vaccine contains up to 20 neoantigens selected by ATLAS™, an ex vivo bioassay screening autologous T-cells for immune responses against both neoantigens and Inhibigens™. Inhibigen-specific T-cells suppress immunity, have been shown to accelerate tumor progression in mice, and are excluded from GEN-009. In cohort A, all patients immunized in the adjuvant setting with GEN-009 monotherapy developed immune responses. Ninety-nine percent of selected peptides were immunogenic: ex vivo CD4+ and CD8+ fluorospot responses specific for 51% and 41% of immunized peptides, respectively.1 Six of 8 patients continue without progression with a median follow up >2 years.MethodsGEN-009 was administered to patients with advanced cancer who received standard-of-care (SOC) PD-1 inhibitor as monotherapy or in combination therapy during vaccine manufacturing. Five vaccine doses were administered over 24 weeks in combination with single agent anti-PD-1. Patients who progressed prior to vaccination received salvage therapy followed by GEN-009 in combination. Peripheral T-cell responses were measured by ex vivo and in vitro stimulated fluorospot assays. Circulating tumor (ct) DNA levels were evaluated in a subset of patients pre- and post-GEN-009 administration.Results15 patients received GEN-009 in combination with PD-1 inhibitor; 1 patient received GEN-009 monotherapy. Median number of neoantigens per vaccine was 14 (range 5–18). GEN-009-related adverse events were limited to vaccine injection site reactions, mild myalgias or fatigue. Sequential vaccination with GEN-009 had an additive effect on the magnitude of ex vivo T-cell responses, that persisted in some patients for 12+ months post first vaccine dose. An association between proportion of peptides eliciting significant cytokine responses and RECIST response is apparent. Epitope spread was detected in CD8+ T-cells from CPI-sensitive patients, but not refractory patients. Four patients who responded to PD-1 inhibition followed by disease stabilization then demonstrated further tumor reduction after GEN-009 vaccination. Seven of 9 CPI responsive patients are progression-free 7 to 18 months after first vaccine dose. Three of 7 CPI-refractory patients have experienced unexpected prolonged stable disease, with 2 PR and 1 SD after vaccination lasting up to 10 months. Plasma ctDNA kinetics mirrored RECIST responses in each tested patient; in some responders, all evidence of ctDNA disappeared, including non-targeted antigens.ConclusionsVaccination with GEN-009 alone or in combination with anti-PD-1 was well tolerated. Preliminary data demonstrate induction of robust, durable neoantigen-specific immune responses and epitope spreading in the presence of PD-1 CPI. Broad immunity against tumor specific targets and encouraging patient outcomes support further study.Trial Registration clinicaltrials.gov identifier: NCT03633110ReferencesLam H, et al. An empirical antigen selection method identifies neoantigens that either elicit broad anti-tumor response or drive tumor growth. Cancer Discovery 2021 March;11(3):696–713.Ethics ApprovalThis study was approved by Western Institutional Review Board, approval number 1-1078861-1

5071 Background: Circulating bone biomarkers (BB) are strongly prognostic for OS in castration-resistant PC (CRPC). We prospectively evaluated BB in men with HSPC in S1216, a trial that established new OS benchmarks. We sought to identify patient (pt) subsets with differential OS outcomes as defined by BB. Methods: Markers of bone resorption [CTx;PYD] & formation [CICP;BAP] were assessed. Pts were randomly divided into training (1/3) & validation (2/3) sets. In the training set, recursive partitioning of OS was used to identify the ideal dichotomous cutpoint for each BB & for a combination of biomarker split points to define prognostic groups. In the validation set, Cox PH models were used to assess impact of BB on OS, adjusted for pt & tumor characteristics. Adjusted odds ratios for 3-year OS based on BB & baseline clinical factors were developed using logistic regression to estimate receiver operating characteristic (ROC) curves. Results: Of 1,279 men, 949 had baseline BB. Median age–68y; median PSA-28 ng/dL; Gleason>7: 60%; Zubrod PS 0/1-97%. Values of BB at the median & at cutpoints maximized for OS were identified. For 3 of the BB, the cutpoint was at the ̃85th %ile; for PYD it was at the median. Recursive partitioning algorithms applied to the training set identified 4 groups with differential OS based on a dichotomous split of CTx in combination with additional CICP splits within each group. Hazard ratios (HR) for OS based on elevated BBs are shown. ROC analysis showed that only BAP & PYD had significantly higher AUC(0.73;0.74) compared to AUC of baseline clinical factors(0.71) w/ p=0.02 and 0.03 respectively. There was no evidence of BB x treatment interaction (all p>=0.2). Conclusions: In men initiating ADT for HSPC, elevated BB are strongly prognostic for worse OS. BB levels alone & in combination with pt/tumor characteristics identify unique subsets of men with high probability of being alive at 3 years from ADT initiation. These results validate the clinical value of BB in the HSPC state, extending BB utility beyond CRPC. Clinical trial information: NCT01809691. [Table: see text]

PURPOSE Prostate cancer (PCa) becomes resistant to androgen ablation through adaptive upregulation of the androgen receptor in response to the low-testosterone microenvironment. Bipolar androgen therapy (BAT), defined as rapid cycling between high and low serum testosterone, disrupts this adaptive regulation in castration-resistant PCa (CRPC). METHODS The TRANSFORMER (Testosterone Revival Abolishes Negative Symptoms, Fosters Objective Response and Modulates Enzalutamide Resistance) study is a randomized study comparing monthly BAT (n = 94) with enzalutamide (n = 101). The primary end point was clinical or radiographic progression-free survival (PFS); crossover was permitted at progression. Secondary end points included overall survival (OS), prostate-specific antigen (PSA) and objective response rates, PFS from randomization through crossover (PFS2), safety, and quality of life (QoL). RESULTS The PFS was 5.7 months for both arms (hazard ratio [HR], 1.14; 95% CI, 0.83 to 1.55; P = .42). For BAT, 50% decline in PSA (PSA50) was 28.2% of patients versus 25.3% for enzalutamide. At crossover, PSA50 response occurred in 77.8% of patients crossing to enzalutamide and 23.4% to BAT. The PSA-PFS for enzalutamide increased from 3.8 months after abiraterone to 10.9 months after BAT. The PFS2 for BAT→enzalutamide was 28.2 versus 19.6 months for enzalutamide→BAT (HR, 0.44; 95% CI, 0.22 to 0.88; P = .02). OS was 32.9 months for BAT versus 29.0 months for enzalutamide (HR, 0.95; 95% CI, 0.66 to 1.39; P = .80). OS was 37.1 months for patients crossing from BAT to enzalutamide versus 30.2 months for the opposite sequence (HR, 0.68; 95% CI, 0.36 to 1.28; P = .225). BAT adverse events were primarily grade 1-2. Patient-reported QoL consistently favored BAT. CONCLUSION This randomized trial establishes meaningful clinical activity and safety of BAT and supports additional study to determine its optimal clinical integration. BAT can sensitize CRPC to subsequent antiandrogen therapy. Further study is required to confirm whether sequential therapy with BAT and enzalutamide can improve survival in men with CRPC.

Background GEN-009 is an adjuvanted personalized cancer vaccine containing up to 20 neoantigens selected by ATLAS™, an ex vivo bioassay screening autologous T cells to identify both neoantigens as well as Inhibigens™ empirically and without in silico predictions. Inhibigen-specific T cells suppress immunity and have been shown to accelerate tumor progression in mice. Inhibigens are avoided in GEN-009. Previous data from patients treated with GEN-009 monotherapy showed 99% of selected peptides generated immune responses including ex vivo CD4+ and CD8+ fluorospot responses specific for 51% and 41% of immunized peptides respectively. Methods GEN-009 is being evaluated in patients (pts) with advanced cancer who received standard-of-care (SOC) PD-1 inhibitor as monotherapy or in combination therapy during vaccine manufacturing; they subsequently received 5 vaccine doses over 24 weeks in combination with the PD-1 inhibitor. Patients who progressed prior to vaccination could receive alternate therapy followed by GEN-009 combined with an appropriate salvage regimen. Peripheral T cell responses were evaluated pre-and post-vaccination by dual-analyte fluorospot assays measured both directly ex vivo and after in vitro stimulation. Results As of August 18, 2020, 15 pts received GEN-009 in combination with a PD-1 inhibitor. Their median TMB was 1.37Mut/mb (range 0.31–6.55), with a median of 24 (6–99) neoantigens and 16 (1–86) Inhibigens. The number of neoantigens in each manufactured vaccine ranged from 4–18 (median 13). GEN-009-related adverse events were limited to Grade 1 injection site reactions. Ex vivo T cell responses peaked after the third vaccination for IFNγ and some patients showed evidence of epitope spread. The initial 5 patients are evaluable for antitumor activity with at least 3 months follow up after first vaccination. Three patients experienced early tumor responses followed by stabilization on PD-1 inhibitor SOC and demonstrated a further reduction in tumor volume after GEN-009 vaccination (figure 1). One patient experienced a complete response prior to vaccination and the 5th patient had progression on SOC, but had a Partial Response to salvage and remains stable after vaccination. Conclusions Vaccination with GEN-009 in combination with PD-1 CPI is feasible for patients with advanced solid tumors with little additive toxicity. Preliminary data demonstrate induction of robust, neoantigen-specific immune responses and a potential expansion of stimulatory targets with epitope spreading in the presence of PD-1 inhibitor. Possible additive antitumor activity in combination with PD-1 inhibitors is suggested by tumor shrinkage following GEN-009 dosing. More mature response and immunogenicity data on 10 additional patients is anticipated for November. Trial Registration ClinicalTrials. gov NCT03633110 Ethics Approval The study was approved by Western Institutional Review Board, approval number 1-1078861-1.

Nonadherence to dosing schedules for androgen deprivation therapy increases the risk of testosterone escape for patients with prostate cancer. Two approved formulations of leuprolide acetate, the most commonly prescribed androgen deprivation therapy in the United States, use different extended release delivery technologies: an in situ gel and microspheres. We evaluated the prevalence and impact of late dosing on testosterone suppression for gel and microsphere formulations of leuprolide acetate.We retrospectively analyzed records of patients with prostate cancer treated with gel or microsphere delivery of leuprolide acetate. Analyses used 2 definitions of "month," "28-day" (late dosing after day 28, 84, 112 or 168) and "extended" (late dosing after day 32, 97, 128 and 194). Frequencies of late dosing and associated testosterone values were calculated.A total of 2,038 patients received gel and 8,360 received microsphere formulations of leuprolide acetate. More than 80% and 27% of injections were late for 28-day and extended month, respectively. For 28-day month late injections 10% (gel delivery) and 14% (microsphere delivery) of testosterone values were above 50 ng/dl, and 25% (gel) vs 33% (microsphere) were above 20 ng/dl. For extended month 18% (gel) vs 25% (microsphere) were above 50 ng/dl, and 34% (gel) vs 44% (microsphere) were above 20 ng/dl. Microsphere leuprolide acetate was 1.5 times more likely to have testosterone above 50/20 ng/dl vs gel. Least square mean testosterone was 34 ng/dl (gel) vs 46 ng/dl (microsphere) for 28-day month, and 48 ng/dl (gel) vs 76 ng/dl (microsphere) for extended month.Leuprolide acetate therapies were frequently administered late. Gel formulation demonstrated higher rates of testosterone 50 ng/dl or less and 20 ng/dl or less than microsphere formulation. Optimal testosterone suppression can impact prostate cancer progression and patient survival, and differences in extended release technology for androgen deprivation therapy appear relevant.

287 Background: RCC has a distinct pattern of metastatic spread with common sites of metastasis including the lung, bone, and liver. Less common sites include the brain, adrenal gland, and pancreas. While the pattern of metastatic spread has prognostic significance, the biology driving tropism to specific organ sites has not been fully characterized. We utilized a multi-institutional real-world dataset to examine genomic alterations and transcriptional signatures across the spectrum of metastatic sites in patients with RCC. Methods: RCC tissue specimens derived from the kidney and distant metastatic sites were sequenced utilizing a commercially available Clinical Laboratory Improvement Amendments (CLIA)-certified assay by Caris Life Sciences. Whole exome and transcriptome sequencing was performed. Molecular subgroups were defined according to the IMmotion151 metastatic RCC subtypes, with subgroups determined by a weighted average of gene expression levels. Molecular analysis and PD-L1 expression (SP142) were described by metastasis site. Results: 657 RCC samples from 653 patients underwent molecular profiling. The median age was 62 years (range 14-90) and the majority were male (70.6%). The most common histology was clear cell RCC (n = 509, 77.5%), followed by papillary (n = 63, 9.6%), chromophobe (n = 30, 4.6%), medullary (n = 8, 1.2%), collecting duct (n = 6, 0.9%), and mixed (n = 41, 6.2%). Specimen source included the kidney (n = 340, 51.8%), lung (n = 75, 11.4%), bone (n = 45, 6.8%), lymph nodes (n = 34, 5.2%), liver (n = 28, 4.3%), endocrine glands (adrenal, pancreas, and thyroid; n = 23, 3.5%), brain/CNS (n = 16, 2.4%), and other metastatic sites (n = 96, 14.6%). Compared to kidney, several genes were mutated at higher rates for select metastatic sites, including PBRM1 (59.5% bone, 59.1% endocrine, and 45.9% lung vs 33.8% kidney, p< 0.05) and KDM5C (27.8% endocrine, 29.2% lymph nodes, and 35.3% soft tissue vs 9.3% kidney, p< 0.05). When evaluating metastatic specimens versus kidney specimens, bone metastases had a significantly higher proportion of tumors classified as ‘Angio/stromal’ (n = 19, 42.2%; vs n = 52, 15.4%; p< 0.0001), while liver metastases had a higher proportion of the ‘complement/Ω-oxidation’ subgroup (n = 17, 60.7%; vs n = 48, 14.1%; p< 0.0001). PD-L1 expression in metastatic sites (range 6.8%-21.7%, with exception of 0% in GI; p= 0.09 to 0.99) was not significantly different from the kidney (16.6%). Conclusions: In our contemporary real-world analysis, we demonstrate differential patterns of molecular alterations among sites of metastasis in RCC. Our observations elucidate the biology underlying heterogeneous disease outcomes associated with site of metastasis. Application of predictive signatures by site of metastasis may help inform personalized therapy strategies in advanced RCC. Further studies are warranted to validate our findings.

Intra-operatively placed cryopreserved placental tissue allograft (CPTA) has shown promise in expediting the recovery urinary continence (UC) following robot-assisted radical prostatectomy (RARP). In this retrospective review of a prospectively maintained single-surgeon, single-institution RARP database, we compare three groups of patients: historical controls (C; N = 183 men) that received no allograft versus two different CPTA products (total CPTA N = 162 [A1 N = 81; A2 N = 81]). The CPTA product was intra-operatively placed as an onlay over the area of the neurovascular bundles during RARP. CPTA cases had significantly faster median time to UC (A1 = 1.4 months; A2 = 1.45 months) versus controls (1.64 months), p = 0.01. On multivariable analysis, use of A1 (HR 1.55, 95% CI [1.14–2.09], p = 0.005) and use of A2 (HR 1.53, CI [1.11–2.11], p = 0.01) were significantly associated with quicker return of UC. Older age (HR 0.97, CI [0.96–0.99], p = 0.001) and non-organ-confined clinical stage (HR 0.51, CI [0.26–1.0] p = 0.05), were significantly associated with slower return of UC. In a propensity score-matched analysis of 77 CPTA patients with sufficient follow-up versus controls, there was significantly less biochemical recurrence (BCR; p = 0.01). Our study indicates that CPTA use appears to accelerate time to UC in age- and performance status-matched men undergoing RARP without increased risk of BCR.

Background: Radium-223 is approved for treatment of bone metastases in metastatic castration-resistant prostate cancer (mCRPC). After the ALSYMPCA trial showed overall survival benefit with the addition of radium-223 to standard of care in mCRPC in 2013, there have been numerous publications and trials using radium-223 in mCRPC. Recently, there has been interest in using radium-223 earlier in the metastatic prostate cancer timeline, in metastatic castrate-sensitive prostate cancer (mCSPC); however, currently, radium-223 in mCSPC treatment is investigational. Aim: A literature search was conducted to review the use of radium-223 in mCSPC treatment from 1980 to 2019. A review of both radium-223 articles and abstracts was performed. Search terms included metastatic prostate cancer and radium-223, mCSPC, hormone-sensitive metastatic prostate cancer, radium-223, and oligometastatic disease. The results were limited to studies involving multiple patients with mCSPC. Conclusion: There are a limited number of studies of radium-223 in mCSPC treatment and the authors report on these studies (two published studies and four ongoing trials). Trials are currently underway to assess if radium-223 could be used in mCSPC as a treatment for bone metastases and micrometastases. Future data from these trials will be informative as to the benefit of radium-223 in mCSPC treatment and may change treatment paradigms for mCSPC. This review will focus on trials assessing the role of radium-223 in mCSPC.

Until the advent of T cell check point inhibitors standard second-line therapy for patients with metastatic urothelial cancer (mUC) was undefined. Histone deacetylase inhibitors (HDACi) have anti-cancer activity in a variety of tumor models including modulation of apoptosis in bladder cancer cell lines. We evaluated the efficacy and toxicity of the HDACi vorinostat in patients with mUC failing first-line platinum-based therapy either in the adjuvant/neoadjuvant setting or for recurrent/advanced disease.Vorinostat was given orally 200 mg twice daily continuously until progression or unacceptable toxicity. The primary end point was RECIST response rate (RR); a RR 20% was deemed interesting in a 2-stage design requiring one response in the first 12 patients to proceed to 2nd stage for a total of 37 subjects. CT or MRI scan imaging occurred every 6 weeks.Fourteen patients were accrued characterized by: median age 66 years (43-84); Caucasian (79%); males (86%); and Karnofsky performance status ≥90 (50%). Accrual was terminated in the first stage as no responses were observed. Best response was stable disease (3 patients). Progression was observed in 8 patients. Two patients came off therapy prior to re-imaging and a 3rd patient died while on treatment and was not assessed for response. Median number of cycles was 2 (range 1-11). Median disease-free survival and overall survival times were 1.1 (0.8, 2.1)3.2 (2.1, 14.5) months, respectively. Toxicities were predominantly cytopenias and thrombocytopenic bleeding. Two pts. had grade 5 toxicity unlikely related to treatment. Two pts. had grade 4 and 6 had grade 3 toxicities observed. Two patients with stable disease remained on therapy for 6+ cycles.Vorinostat on this dose-schedule had limited efficacy and significant toxicity resulting in a unfavorable risk:benefit ratio in patients with mUC. NCT00363883.

Contains fulltext : 220820.pdf (Publisher’s version ) (Open Access) BACKGROUND: Multiple loss-of-function alterations in genes that are involved in DNA repair, including homologous recombination repair, are associated with response to poly(adenosine diphosphate-ribose) polymerase (PARP) inhibition in patients with prostate and other cancers. METHODS: We conducted a randomized, open-label, phase 3 trial evaluating the PARP inhibitor olaparib in men with metastatic castration-resistant prostate cancer who had disease progression while receiving a new hormonal agent (e.g., enzalutamide or abiraterone). All the men had a qualifying alteration in prespecified genes with a direct or indirect role in homologous recombination repair. Cohort A (245 patients) had at least one alteration in BRCA1, BRCA2, or ATM; cohort B (142 patients) had alterations in any of 12 other prespecified genes, prospectively and centrally determined from tumor tissue. Patients were randomly assigned (in a 2:1 ratio) to receive olaparib or the physician's choice of enzalutamide or abiraterone (control). The primary end point was imaging-based progression-free survival in cohort A according to blinded independent central review. RESULTS: In cohort A, imaging-based progression-free survival was significantly longer in the olaparib group than in the control group (median, 7.4 months vs. 3.6 months; hazard ratio for progression or death, 0.34; 95% confidence interval, 0.25 to 0.47; P

We evaluated the timeliness of androgen deprivation therapy dosing, the impact of dosing nonadherence on testosterone, and the frequency of testosterone and prostate specific antigen testing in patients with prostate cancer.We retrospectively analyzed the records of 22,860 patients with prostate cancer treated with luteinizing hormone-releasing hormone agonists. Analyses were done using 2 definitions of month, including a 28-day month (late dosing after day 28, 84, 112 or 168) and an extended month (late after day 32, 97, 128 or 194) for 1, 3, 4 and 6-month formulations, respectively. The prevalence of late dosing, associated testosterone values, and the frequency of testosterone and prostate specific antigen testing were assessed. Statistical significance was assessed with the unpaired t-test.Of the injections 84% and 27% were late for the 28-day and extended month analyses, respectively. For the 28-day month 60% and 29% of injections were late by more than 1 and more than 2 weeks, respectively. Of testosterone values 4% were greater than 50 ng/dl for early/on time injections using both definitions, and 15% and 27% were greater than 50 ng/dl when late, and for the 28-day month and the extended month, respectively. For early/on time vs late injections 22% vs 31% of testosterone values were greater than 20 ng/dl for the 28-day month and 21% vs 43% for the extended month. Mean testosterone was higher when lateLuteinizing hormone-releasing hormone agonists were frequently (84%) administered later than the schedules used in pivotal trials. Nearly half of the late testosterone values for the extended month were greater than 20 ng/dl and mean testosterone was almost double the castration level. Elevated testosterone remained unidentified with infrequent testing.

Purpose To determine whether cotargeting poly (ADP-ribose) polymerase-1 plus androgen receptor is superior to androgen receptor inhibition in metastatic castration-resistant prostate cancer (mCRPC) and whether ETS fusions predict response. Patients and Methods Patients underwent metastatic site biopsy and were stratified by ETS status and randomly assigned to abiraterone plus prednisone without (arm A) or with veliparib (arm B). Primary objectives were: confirmed prostate-specific antigen (PSA) response rate (RR) and whether ETS fusions predicted response. Secondary objectives were: safety, measurable disease RR (mRR), progression-free survival (PFS), and molecular biomarker analysis. A total of 148 patients were randomly assigned to detect a 20% PSA RR improvement. Results A total of 148 patients with mCRPC were randomly assigned: arm A, n = 72; arm B, n = 76. There were no differences in PSA RR (63.9% v 72.4%; P = .27), mRR (45.0% v 52.2%; P = .51), or median PFS (10.1 v 11 months; P = .99). ETS fusions did not predict response. Exploratory analysis of tumor sequencing (80 patients) revealed: 41 patients (51%) were ETS positive, 20 (25%) had DNA-damage repair defect (DRD), 41 (51%) had AR amplification or copy gain, 34 (43%) had PTEN mutation, 33 (41%) had TP53 mutation, 39 (49%) had PIK3CA pathway activation, and 12 (15%) had WNT pathway alteration. Patients with DRD had significantly higher PSA RR (90% v 56.7%; P = .007) and mRR (87.5% v 38.6%; P = .001), PSA decline ≥ 90% (75% v 25%; P = .001), and longer median PFS (14.5 v 8.1 months; P = .025) versus those with wild-type tumors. Median PFS was longer in patients with normal PTEN (13.5 v 6.7 months; P = .02), TP53 (13.5 v 7.7 months; P = .01), and PIK3CA (13.8 v 8.3 months; P = .03) versus those with mutation or activation. In multivariable analysis adjusting for clinical covariates, DRD association with PFS remained significant. Conclusion Veliparib and ETS status did not affect response. Exploratory analysis identified a novel DRD association with mCRPC outcomes.

BackgroundSkeletal metastases often occur in men with castration-resistant prostate cancer (CRPC) where bone biomarkers are prognostic for overall survival (OS). In those with highly elevated markers, there is preferential benefit from bone-targeted therapy. In the phase IIIS0421 docetaxel +/- atrasentan trial, clinical covariates and bone biomarkers were analyzed to identify CRPC subsets with differential outcomes.Subjects and methodsMarkers of bone resorption [N-telopeptide-NTx; pyridinoline-PYD] and formation [C-terminal collagen propeptide-CICP; bone alkaline phosphatase-BAP] were measured in pre-treatment sera. Bone biomarkers and clinical covariates were included in a Cox model for OS; bone markers were added in a stepwise selection process. Receiver operating characteristic (ROC) curves were constructed for risk factor models +/- bone markers. Significant variables were allowed to compete in a classification and regression tree (CART) analysis. Hazard ratios(HR) were calculated by comparing OS in each of the terminal nodes to a reference group in a Cox model.Results750 patients were included. Each bone marker significantly contributed to the risk factor-adjusted OS Cox model, with higher levels associated with worse OS. BAP (HR = 1.15, p = 0.008), CICP (HR = 1.27, p

BackgroundAGEN1181 is a novel anti-CTLA-4 antibody with enhanced FcyR-dependent functionality, engineered to bind high and low binding alleles of FcyRIIIA, promoting superior T cell priming, memory responses, and depletion of intratumoral T regulatory cells. Further, AGEN1181 avoids complement recruitment, predictive of better tolerability. Here we report initial safety and efficacy findings from a phase I/Ib study of AGEN1181 as monotherapy and in combination with balstilimab (BAL; anti-PD-1).MethodsEligible patients (pts) had advanced solid tumors refractory to standard therapies. AGEN1181 was dosed Q3W (0.1–3 mg/kg) or Q6W (1–2 mg/kg) as monotherapy, or Q6W (0.1–2 mg/kg) in combination with BAL Q2W (3 mg/kg).ResultsAs of July 16th 2021, 102 pts received AGEN1181 (43 monotherapy, 59 combination). Median age, 63 years (29–83); 50.5% with ≥3 prior lines of therapy. MTD not yet reached with AGEN1181 dosing up to 3 mg/kg Q3W as monotherapy and 2 mg/kg in combination with BAL. The most common treatment-related adverse events (TRAEs) of any grade were fatigue (34.3%), diarrhea (32.4%), and nausea (19.6%) with grade ≥3 events in 21.6% (diarrhea/colitis, 11.8%, fatigue, 2.9%). Notably, no immune-related hypophysitis or pneumonitis has been observed. Discontinuation from AGEN1181 due to TRAEs occurred in 15% of pts. Grade 5 TRAEs occurred in two pts (colitis [chronic], intestinal perforation). The disease control rate in evaluable pts (completed ≥1 on-treatment scan) defined as best overall response of CR, PR, or SD ≥6 weeks was 48.1% for AGEN1181 monotherapy ≥1 mg/kg (1 CR, 3 PR, 9 SD) and 70% for combination (3 PR, 6 unconfirmed PR [uPR], 19 SD). Monotherapy responders include individual pts with MSS endometrial cancer (CR), PD-1-relapsed/refractory cervical cancer (PR), PD-1-relapsed/refractory melanoma (PR), and pancreatic cancer (PR). Enrollment is continuing in several disease expansion cohorts with combination therapy. For MSS CRC, 2 PR, 2 uPR, and 7 SD have been seen in 17 evaluable ≥1 mg/kg patients to date. In the ovarian cohort (n=6), 2 PRs and 3 SD are noted. Additional combination responders include one PR and uPR in MSS endometrial cancer, two uPRs in visceral angiosarcoma (uPRs) and one uPR in PD-1-relapsed/refractory NSCLC (uPR); the majority of the responses are recent and ongoing.ConclusionsAGEN1181 alone and in combination with BAL demonstrates favorable tolerability and compelling clinical activity, notably in poorly immunogenic tumor types and PD-1-refractory pts. These results underscore the significant potential of AGEN1181 to expand benefit of anti-CTLA-4 therapy to a broader patient population.Trial RegistrationNCT03860272Ethics ApprovalThe study obtained ethics approval at each participating center (UT Health Sciences Center at San Antonio, University of Colorado Cancer Center, St John’s Cancer Institute, and HonorHealth under WIRB Study number 1256391; USC Norris Comprehensive Cancer Center, Beth Israel Deaconess Medical Center, and MD Anderson Cancer Center, approval numbers HS19-00277, 19–132, and 140346, respectively). All patients provided written informed consent in accordance with federal, local, and institutional guidelines.

Background Two androgen receptor (AR)-targeted therapies, enzalutamide and abiraterone acetate plus prednisone (abiraterone), have been approved for the treatment of metastatic castration-resistant prostate cancer (CRPC). Many patients respond to these agents, but both de novo and acquired resistance are common. The authors characterized resistant phenotypes that emerge after treatment with abiraterone or enzalutamide. Methods Patients who received abiraterone or enzalutamide in the course of routine clinical care were consented for serial blood collection. A proprietary system (CellSearch) was used to enumerate and enrich circulating tumor cells (CTCs). RNA-sequencing (RNA-seq) was performed on pools of up to 10 epithelial cell adhesion molecule (EpCAM)-positive/CD45-negative CTCs. The impact of gene expression changes observed in CTCs between patients who responded or were resistant to abiraterone/enzalutamide therapies was further explored in a model cell line system. Results RNA-seq data from CTCs identified mutations commonly associated with CRPC as well as novel mutations, including several in the ligand-binding domain of AR that could facilitate escape from AR-targeted agents. Ingenuity pathway analysis of differentially regulated genes identified the transforming growth factor β (TGFβ) and cyclin D1 (CCND1) signaling pathways as significantly upregulated in drug-resistant CTCs. Transfection experiments using enzalutamide-sensitive and enzalutamide-resistant LNCaP cells confirmed the involvement of SMAD family member 3, a key mediator of the TGFβ pathway, and of CCND1 in resistance to enzalutamide treatment. Conclusions The current results indicate that RNA-seq of CTCs representing abiraterone and enzalutamide sensitive and resistant states can identify potential mechanisms of resistance. Therapies targeting the downstream signaling mediated by SMAD family member 3 (SMAD3) and CCND1, such as cyclin-dependent kinase 4/cyclin-dependent kinase 6 inhibitors, could provide new therapeutic options for the treatment of antiandrogen-resistant disease. Cancer 2018;124:1216-24. © 2017 American Cancer Society.

Background: Papillary renal cell carcinoma (pRCC) is associated with EGFR expression and activation of MET signaling pathway. A randomized multicenter parallel two-stage phase II trial of MET inhibitor tivantinib alone or in combination with EGFR inhibitor erlotinib was conducted in patients with pRCC. Methods: Patients with advanced pRCC and 0-1 prior systemic therapy were randomly assigned to tivantinib 360 mg BID (Arm 1) or tivantinib 360 mg BID plus erlotinib 150 mg daily (Arm 2). Target max accrual was 70 patients (35 per arm) with interim analysis planned after enrollment of 20 patients per arm. Results: Six % of patients had type 1 pRCC, 42% had type 2, and 52% had no subtype assigned. The study was closed after the first stage when both arms yielded RR of 0%. Median progression free survival (PFS) was 2.0 and 3.9 months, and OS was 10.3 and 11.3 months in Arms 1 and 2 respectively. Treatment was well tolerated. Exome of tumor tissue from 16 patients were successfully sequenced using Agilent SureSelect probes. Only 1 of 16 samples harbored MET mutation. Other mutations associated primarily with type 2 pRCC were noted and included CDKN2A, PBRM1, SETD2, KDM6A, FAT1 and NF2. Conclusions: Tivantinib - either alone or in combination with erlotinib has no clinical activity in patients with advanced pRCC. The S1107 cohort had a low proportion of patients with MET alterations. MET remains a reasonable therapeutic target in pRCC, but selection of patient subsets exhibiting MET activation may be required to better benefit from therapy with MET inhibitors.

Purpose: There are limited long-term data on patients treated with image guided intensity modulated radiation therapy (IG-IMRT) for prostate cancer recurrence or high-risk disease features after radical prostatectomy. We report single-institution results for patients treated with IG-IMRT and identify variables associated with outcome. Methods and materials: This is a retrospective chart review consisting of 313 consecutive patients who were treated with adjuvant or salvage IG-IMRT from 2004 to 2013. Cox proportional hazards analysis was used to identify factors related to survival and toxicity. Toxicity was graded using the Common Terminology Criteria for Adverse Events Version 4.0. Results: The median follow-up was 55 months (range, 6-131 months). The median pre-radiation therapy (RT) prostate-specific antigen (PSA) was 0.3 ng/mL (range, 0.2 ng/mL), biopsy Gleason score (≥7 [4+3]), and duration of ADT (>6 months) were significantly associated (P < .05) with biochemical progression-free survival. Actuarial late grade 3 genitourinary and gastrointestinal toxicities at 5 years were 10% and 2%, respectively. Conclusion: Our results suggest that lower pre-RT PSA level and longer duration of ADT are associated with improved biochemical control. The incidence of late grade 3 gastrointestinal toxicity was low, but late grade 3 genitourinary toxicity was higher than anticipated.

Prostate cancer is the second leading cause of death in men in the developed countries. Androgen deprivation therapy (ADT) is commonly used to treat prostate tumors at earlier stages due to hormone-dependence of cancer cells. However, the onset of androgen-resistance with tumor progression and the negative impact of ADT on the quality of life are significant challenges. To address these issues, we have initiated a novel clinical trial combining radium Ra223 dichloride with stereotactic body radiation treatment (SBRT) and short course of ADT in patients with oligometastatic, castration-sensitive prostate cancer (NCT03351735). Patients with one to four oligometastatic prostate cancer lesions have been receiving ADT for nine months, together with SBRT to all metastatic sites and six cycles of Ra223 to target micrometastatic bone lesions. Eight out of the planned 24 patients have already completed the full treatment course, with five patients currently on surveillance (not requiring any further treatment) and three patients receiving next cycle of therapy. As part of this investigator-initiated study, we have performed a comprehensive immune characterization of peripheral immune cells and serum immune biomarkers in all treated patients. Based on flow cytometric analysis, we found a significant decrease in the percentage of CD4+ T cells befoe and after SBRT (cycle 1) but no changes in the elevated levels of programmed cell death-1 (PD-1), a marker of T-cell exhaustion, on the circulating CD4+ and CD8+ T cells. In addition, we observed high levels of the activated STAT3 (pSTAT3) in myeloid-derived suppressor cells (MDSCs), together with its downstream target Arginase-I. Finally, IL-8 stood out as a cytokine strongly elevated in plasma of patients who received the complete Ra223 treatment but not directly after SBRT. Overall, these preliminary results suggest that this combinatorial radiotherapy patients with oligometastatic prostate cancers impacts immune cell activity but rather than leading to T cell activation it may promote tolerogenic activity of MDSCs. Citation Format: Marice Alcantara, Tanya Dorff, Jessica Liu, Paul Frankel, Przemyslaw Twardowski, Savita Dandapani, Marcin Kortylewski. Immune biomarkers of response to Ra223 dichloride and stereotactic body radiation therapy in patients with oligometastatic prostate cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 677.

5001 Background: Tak is an oral selective nonsteroidal 17, 20-lyase inhibitor that blocks the synthesis of gonadal and adrenal androgens. We evaluated the clinical benefit of Tak with ADT in pts with newly diagnosed mHSPC. Methods: Pts with mHSPC with a Zubrod performance status (PS) of 0-2 and a PSA of ≥ 2 ng/ml were randomized 1:1 to ADT+Tak (300 mg twice daily) or ADT+Bic (50 mg daily). Stratification factors included PS (0-1 vs ≥2), extent of disease (minimal vs extensive), and receipt of ADT prior to registration (yes vs no). The primary endpoint was overall survival (OS). Secondary endpoints were progression free survival (PFS; based on PSA, imaging or clinical progression), PSA at 7 months (≤0.2 vs 0.2 < PSA; ≤-4 vs. > 4 ng/ml) and adverse event (AE) profile. With 2.75 yrs to accrue 1,186 eligible pts and 3 additional yrs of follow-up, we would have 90% power to determine a 33% improvement in OS from 54 to 72 mos (1-sided α = 0.025). A final analysis was pre-specified after 523 deaths using a 1-sided α = 0.022 to account for interim analyses. Results: Between 3/2013 and 7/2017, 1,313 pts were randomized and 1,279 were included in the intention-to-treat (ITT) analysis (32 pts were ineligible and 2 pts withdrew consent). Median age was 68 yrs and 10% of subjects were Black. Median PSA was 30 ng/mL (range 2-6710) and 49% of pts had extensive disease. After a median follow-up of 4.9 yrs, PFS and PSA response were significantly improved with Tak over Bic but no significant improvement in OS was observed (Table). More grade 3/4 AEs occurred in Tak vs. Bic arms (43% vs. 14%), and included hypertension (20% vs. 5%) and fatigue (5% vs. 2%). Five pts in Tak and 1 pt in the Bic arm had grade 5 AE. Conclusions: Despite clinically meaningful improvement in various outcome measures with Tak+ADT over Bic+ADT in this representative population of mHSPC, the improvement in OS did not meet the pre-specified criteria for statistical significance. The median OS of 70 mos in the control arm (standard ADT) was higher than that reported in contemporary phase 3 trials in this setting, and 16 mos higher than originally estimated. This trial sets a new landmark for survival estimates when pts with mHSPC have access to multiple approved subsequent life-prolonging therapies. Funding: NIH/NCI/NCTN grants U10CA180888, U10CA180819, U10CA180820; U10CA180821; and in part by Millennium Pharmaceuticals, Inc. (Takeda Pharmaceutical Company LTD) Clinical trial information: NCT01809691. [Table: see text]

2613 Background: GEN-009 is an adjuvanted personalized cancer vaccine containing up to 20 neoantigens selected by ATLAS, an ex vivo bioassay screening autologous T cells for immune responses against both neoantigens as well as Inhibigens. Inhibigen-specific T cells suppress immunity and have been shown to accelerate tumor progression in mice and are avoided in GEN-009. In cohort A, all patients immunized in the adjuvant setting with GEN-009 monotherapy developed immune responses. Nearly all (99%) of selected peptides were immunogenic: ex vivo CD4+ and CD8+ fluorospot responses specific for 51% and 41% of immunized peptides, respectively. Seven of 8 patients continue without progression with a median follow up of 18 months. Methods: GEN-009 is being evaluated in patients (pts) with advanced cancer who received standard-of-care (SOC) PD-1 inhibitor as monotherapy or in combination therapy during vaccine manufacturing. Five vaccine doses were administered over 24 weeks in combination with a PD-1 CPI. Patients who progressed prior to vaccination received alternative salvage therapy followed by GEN-009 in combination. Peripheral T cell responses were measured by fluorospot assays in ex vivo and in vitro stimulation. Results: 15 pts received GEN-009 in combination with a PD-1 inhibitor; 1 patient received GEN-009 monotherapy. Median number of neoantigens per vaccine was 14 (5-18). GEN-009-related adverse events were limited to vaccine injection site reactions and mild myalgias or fatigue. Longitudinal evaluation of ex vivo T cell responses revealed that sequential vaccination with GEN-009 had an overall additive effect on the robustness of IFNγ secretion and responses were persistent for at least 6 months in some patients. Epitope spread was detected in CPI sensitive patients, but not in CPI refractory patients receiving salvage therapy. Three patients who responded to PD-1 inhibition followed by disease stabilization then demonstrated further reduction after GEN-009 vaccination that could represent vaccine effect. Eight of 9 CPI responsive patients are progression-free from 3 to 10 months after first vaccine dose. Four of 7 CPI refractory patients have experienced unexpected prolonged stable disease after vaccination of up to 8 months after vaccination. 2 of 2 patients with available samples lost all evidence of circulating tumor DNA including non-targeted neoantigens. Conclusions: Vaccination with GEN-009 in combination with anti-PD-1 CPI in patients with advanced solid tumors shows little additive toxicity. Preliminary data demonstrate induction of broad neoantigen-specific immune responses and epitope spreading in the presence of PD-1 CPI. Broad immunity against tumor specific targets and encouraging patient outcomes support further study. Clinical trial information: NCT03633110.

Background Oral metronomic chemotherapy, which has low toxicity, has demonstrated promising anti-tumor and anti-angiogenic properties that may lead to prolonged progression-free survival and improved response rates in patients with recurrent epithelial ovarian cancer (EOC). These effects may be enhanced by the co-administration of anti-angiogenic agents. Methods We conducted a randomized phase II clinical trial to evaluate the therapeutic benefit of oral metronomic cyclophosphamide (CTX) alone and with the anti-angiogenic drug celecoxib in patients with gynecological malignancies. 52 patients were randomly assigned to two treatments arms: 50 mg oral CTX daily alone (Arm A) or with 400 mg celecoxib twice daily (Arm B). The primary endpoint was response rate. Secondary endpoints included toxicity, time to treatment failure, and overall survival. Results In Arm A (n = 26), 3 patients (12%) had stable disease >6 months and 1 (4%) had a partial response. In Arm B, 5 (19%) had stable disease >6 months and 1 patient (4%) had a partial response. There were no significant between-group differences in overall survival (9.69 months [95% CI 3.84–13.18] vs. 12.55 months [6.67–17.61]) or in median time to treatment failure (1.84 months [1.68–2.76] vs. 1.92 months [1.64–5.22]). The most common adverse events were nausea, vomiting, and abdominal pain. Conclusions Oral metronomic CTX has activity with no major toxicities in heavily pretreated recurrent gynecological cancers and may be considered in patients with indolent disease. We did not observe any additional benefit of celecoxib treatment, though this may be due to small sample sizes.

Purpose Contemporary treatment for metastatic hormone sensitive prostate cancer (mHSPC) includes androgen deprivation therapy (ADT) plus abiraterone or docetaxel. While these intensified regimens have improved efficacy, they are also associated with increased cost and toxicities. Not all men with mHSPC may be candidates for these intensified regimens, yet there are no clinical models or biomarkers used to optimize treatment selection. Herein, we hypothesized that longer time from prior definitive therapy (DT), either radical prostatectomy, definitive radiotherapy, or both, to onset of metastatic disease is associated with improved survival outcomes in men with newly diagnosed mHSPC. Methods This multicenter retrospective study included men initiating systemic therapy with ADT for new mHSPC. Kaplan-Meier and COX proportional hazard models assessed time to metastatic castration-resistant prostate cancer (mCRPC) and overall survival (OS) by receipt of prior DT. Results Of the 253 men with new mHSPC, 115 (45%) had received prior DT. In a multivariate analysis, increasing years from DT to the start of ADT was an independent predictor of time to mCRPC (per year: hazard ratio 0.91 95% confidence interval 0.84–0.99, P = 0.020) and improved OS (per year: hazard ratio 0.87, 95% confidence interval 0.74–0.99, P = 0.0025) in patients with new mHSPC, and may assist with risk stratification in these patients at time of mHSPC. Conclusion Time from DT to start of ADT is an independent predictor of time to mCRPC and OS in men with new mHSPC, and may assist with risk stratification of these patients for systemic therapy selection.

Background Sipuleucel-T is an autologous cellular immunotherapy indicated for patients with asymptomatic or minimally symptomatic metastatic castration resistant prostate cancer (mCRPC). Since radiation therapy (RT) can suppress bone marrow function and immune responses, previous studies evaluating sipuleucel-T excluded patients who received RT less than or equal to 28 days prior to sipuleucel-T therapy. Recent evidence suggests that RT may act synergistically with immunotherapy to enhance and broaden antitumor immune response. Methods Patients who met standard criteria for sipuleucel-T were randomized to receive sipuleucel-T alone (Arm A) or sipuleucel-T initiated 1 week after completing sensitizing RT to single metastatic site (Arm B). RT was delivered at 300cGy/day to 3000 cGy total. The primary endpoint was the ability to safely combine sipuleucel-T preceded by RT and generate sipuleucel-T with adequate product immune activation parameters. Secondary endpoints included the measurement of systemic immune responses to prostatic acid phosphatase (PAP), a target for sipuleucel-T immune therapy and PA20204 (recombinant fusion protein utilized in the generation of sipuleucel-T). Results 51 pts were enrolled, 2 did not receive any sipuleucel-T because of vascular access problems and were excluded. 24 were treated on Arm A, 25 on Arm B. 47/49 patients received all 3 sipuleucel-T infusions. Median age was 66 yrs (range 45–90). Sipuleucel-T product parameters including: total nucleated cell (TNC) count, antigen presenting cell (APC) count were similar in both groups. Cumulative APC upregulation was higher in Arm A. 1 patient in Arm A demonstrated PSA response. Median progression free survival (PFS) was 2.46 months on Arm A and 3.65 months on Arm B (p = 0.06). Both arms showed similar increases in humoral responses to PA2024 and PAP. IFN-ƴ ELISPOT T-cell activation responses to PA20204 were observed in both arms, but were more robust in the Arm A (p = 0.028). Both arms were well-tolerated, with fatigue as the most common grade 2 adverse event (1 patient in Arm A and 3 patients in Arm B). Conclusions Sensitizing RT completed 1 week before generation of sipuleucel-T did not affect the majority of product parameters and the ability to deliver sipuleucel-T therapy. RT did not enhance the humoral and cellular responses associated with sipuleucel-T therapy.

Preclinical studies have suggested that VEGFR1-positive cells potentially foster the development of metastases by establishing a “premetastatic niche.” We sought to test this hypothesis in high-risk localized prostate cancer and assess potential niche modulation by the VEGFR1-targeting drug axitinib. Formalin-fixed, paraffin-embedded tissue derived from benign lymph nodes was collected and VEGFR1-positive cell clustering was assessed in benign lymph nodes via IHC. Recursive partitioning was used to define a threshold for VEGFR1 clustering that could segregate patients based on time to biochemical recurrence (TTBR). Multivariate analyses were used to determine whether VEGFR1 clustering, age, pathologic T-stage, Gleason score, or baseline PSA could independently predict TTBR. A randomized, phase II clinical trial comparing axitinib for 28 days followed by radical prostatectomy and pelvic lymph node dissection (RP/PLND) to RP/LND alone was then conducted, with the primary endpoint of demonstrating downregulation of VEGFR1-positve cell clustering in benign lymph nodes. Our retrospective analysis assessed a cohort of 46 patients. A threshold of 1.65 VEGFR1-positive cells per high power field was identified, below which TTBR was delayed. VEGFR1 clustering was an independent predictor of TTBR in a multivariate analysis. Only 11 out of the planned 44 patients were accrued to the phase II trial. While preoperative axitinib was safe and well tolerated, there was no sign of clinical activity or VEGFR1 downregulation. Our results validate previous findings that suggest VEGFR1-positive cells in benign lymph nodes can predict clinical outcome. Further work is needed to develop a viable clinical strategy for modulating VEGFR1 in these tissues. Mol Cancer Ther; 14(12); 2896–900. ©2015 AACR.

3107 Background: Tumor-specific neoantigens provide personalized targets for immunotherapy. Vaccines against epitopes predicted by in silico approaches very rarely induce CD4+ and CD8+ ex vivo T cell responses regardless of formulation. ATLAS selects neoantigens for vaccine inclusion using ex vivo screening of all patient-specific mutations to identify pre-existing CD4+ or CD8+ T cell responses and to exclude Inhibigens, which are inhibitory peptides that suppress immunity and accelerate tumor progression. The Inhibigen burden correlates with patient outcomes in observational studies and rapid tumor progression in mouse models. Methods: GEN-009-101 is a phase 1/2a study testing safety, immunogenicity and clinical activity in immune responsive tumors. After next-generation tumor sequencing and ATLAS testing of autologous leukocytes, up to 20 stimulatory synthetic long peptides adjuvanted with poly-ICLC comprise each personalized vaccine. Eight vaccinated patients have been followed for sustained immunological responses and clinical outcomes. Results: The 40 doses given across patients have induced only mild local discomfort and no DLT. Vaccination has generated immune responses against 99% of administered peptides, with both CD8+ and CD4+ responses in ex vivo fluorospot assays. To date, no patients have developed recurrent disease. Broad immunity develops as early as Day 29 and is sustained for over 12 months. Immune response against individual peptides is correlated with peptide concentration (OR = 1.26, p≤0.0001) but not with other classifiers such as GRAVY index (Grand Average of Hydropathy), tumor type, injection site or sex. The Inhibigen burden prior to treatment again correlates with disease progression. Conclusions: GEN-009 identifies tumor specific immune targets from the individual patient’s tumor mutagens. Initial clinical data show that ATLAS antigen selection may be critical to the induction of broad, rapid and sustained immunity against tumor specific neoantigens. Clinical vaccination with PD-1 blockade is in process. Clinical trial information: NCT03633110 . [Table: see text]

5523 Background: We previously reported that baseline BMB are independently prognostic for overall survival (OS) in men with castration resistant prostate cancer. We correlated BMB with outcomes in mHSPC as part of S1216, a phase III trial of ADT +/- the novel CYP17 inhibitor orteronel. Methods: Blood was obtained at study entry for bone resorption [C-telopeptide(CTx) & Pyridinoline(PYD)] & formation markers [C-terminal collagen propeptide(CICP) & bone alkaline phosphatase(BAP)]. With prior DSMC approval, patients were sampled to mask potential treatment effect. Logistic regression was used to assess if BMB elevation above median was prognostic for a PFS event w/in 2 years across pooled study treatment arms, adjusting for baseline variables (including disease extent, PSA, age, pre-randomization ADT, & presence of bone mets). An additional interaction term between BMB elevation & presence of bone mets was included; if significant, separate models were developed for men +/- bone mets. Results: Of 1,313 men, 656 were included in this analysis. All 4 BMB levels were higher in men with a PFS event w/in 2 years vs. those with no PFS event. The odds ratio (OR) for a PFS event was significantly higher in men w/ elevated baseline BMB (see table). For BAP, a significant interaction between marker elevation and bone mets was seen (p = 0.003); men w/ bone mets and BAP elevation had an OR of 1.83 for a PFS event in 2 years. Conclusions: In men with newly diagnosed HSPC, elevated baseline levels of BMB were significantly associated with PFS, with about a two-fold increased risk of a progression event w/in 2 years. For CICP, CTx, & PYD, this association was independent of the presence of bone metastases. Baseline BMB levels have strong prognostic value in the mHSPC context. Correlative analysis of BMB & OS is planned. Clinical trial information: NCT01809691 . [Table: see text]