Progressive mCRPC Research Articles

Randomized phase II trial of radium-223 (RA) plus enzalutamide (EZ) versus EZ alone in metastatic castration-refractory prostate cancer (mCRPC): Long-term follow up of secondary endpoints.

125 Background: RA, a bone targeting alpha radiopharmaceutical, and EZ, are approved for mCRPC. Per phase 3 SWOG0421 trial, men with mCRPC and a significant decline in serum bone metabolism markers (BMM) had improved survival with atrasentan, a bone targeting agent (PMID 24565955). We hypothesized that RA+EZ is safe, and decrease bone metabolism markers compared to EZ alone. Here we report the long-term follow up of the secondary clinical endpoints. Methods: In this phase 2 trial (NCT02199197), men with progressive mCRPC were treated with EZ (160 mg daily) ± RA (standard dose of 55 kBq/kg IV Q4 weeks x 6), until disease progression or unacceptable toxicities. Primary objectives: 1) changes in N-telopeptide compared from baseline to end of treatment; 2) safety. Secondary objectives: changes in 4 other markers of bone resorption or formation, and PSA progression free survival (PSA-PFS), radiographic PFS (rPFS) and overall survival (OS). Results: After a safety lead in phase (n=8), 39 men were randomized (2:1) to RA+EZ vs EZ. Median follow up is 19.3 months (range 3 – 24 months). Combining RA+EZ was safe (2018 ASCO annual meeting abstract: 5057) and met the primary endpoint (2018 ESMO annual meeting: Annals of Oncology). There was a consistent trend regarding PSA-PFS, rPFS and OS favoring RA+EZ over EZ. . . (Table). Notably, no bone fractures have occurred in either group with extended follow up. Conclusions: The use of RA+EZ was safe with a longer follow up with no increase in skeletal related events including fractures. All secondary endpoints, numerically favored RA+EZ vs EZ. Clinical trial information: NCT02614859.

ADRB2 expression in progressive metastatic castration-resistant prostate cancer.

145 Background: The net oncogenic effect of the G protein-coupled receptor β2 adrenergic receptor ADRB2, which may induce neuroendocrine differentiation via cyclic AMP and protein kinase A and whose expression is epigenetically regulated by EZH2, is controversial. ADRB2 expression and associated clinical outcomes in metastatic castration-resistant prostate cancer (mCRPC) are unknown. Methods: This was a retrospective analysis of a cohort of men with mCRPC who were prospectively enrolled in the multi-center SU2C/PCF/AACR West Coast Prostate Cancer Dream Team study, in which biopsies of a metastatic site were obtained at disease progression. Specimens underwent laser capture microdissection and RNA-seq. ADRB2 expression was stratified by histology and transcriptional cluster based on prior unsupervised hierarchical transcriptome clustering, and correlated with EZH2 expression. ADRB2 expression (lowest quartile) was correlated with OS from time of biopsy by log rank test and a multivariable Cox proportional hazard model. Results: One-hundred and twenty-seven men with progressive mCRPC underwent metastatic biopsies and had sufficient tumor for RNA-seq. ADRB2 expression was lowest in the small cell-enriched transcriptional cluster (P<0.001), and correlated inversely with EZH2 expression (r=-0.28, P<0.01). Men with low ADRB2 expression had a shorter median OS than those with high (9.5 vs 18.9 mo, P=0.02). In multivariable analysis adjusting for small cell histology, performance status, LDH, and visceral metastases, high ADRB2 expression was associated with a trend towards longer OS (HR=0.65, 95% CI 0.41-1.02, P=0.06). Conclusions: Low ADRB2 expression is associated with worse OS in men with progressive mCRPC, and may be a means by which EZH2 confers resistance to antiandrogen therapy. Indirect ADRB2 stimulation with EZH2 inhibitors may improve outcomes. Validation in independent cohorts is necessary.

SHR3680, a novel antiandrogen, for the treatment of metastatic castration-resistant prostate cancer (mCRPC): A phase I/II study.

90 Background: SHR3680 is a novel and pure androgen-receptor (AR) antagonist that shows a potent antitumor activity against CRPC but with much less brain distribution than enzalutamide in preclinical study. In this first-in-human phase 1/2 study, the safety and efficacy of SHR3680 were assessed in patients with mCRPC. Methods: This phase 1/2 study was conducted in 11 hospitals in China. Patients with progressive mCRPC that was not previously treated with novel AR-targeted agents were eligible for this study. In the phase 1 part, patients received oral SHR3680 at a starting daily dose of 40 mg, which was subsequently escalated to 80 mg, 160 mg, 240 mg, 360 mg, and 480 mg. In phase 2, patients were randomized to receive one of three daily doses of SHR3680 (80 mg, 160 mg, and 240 mg). The primary endpoint in phase 1 was safety and tolerability, and in phase 2 was the proportion of patients with a PSA response (≥50% decrease of PSA level at week 12). Results: From Apr 2016 to Sep 2018, a total of 197 patients (median age 67 years, range 45−80; visceral metastases in 29 patients; previous chemotherapy history in 80 patients) were enrolled (phase 1, n = 18; phase 2, n = 179). No dose-limiting toxicities were reported and the maximum tolerated dose was not reached. Most adverse events were grade 1/2 (87.3%). The most common adverse events were anemia (22.8%), back pain (16.2%), and proteinuria (13.2%). The antitumor activity was observed at all doses, including PSA response in 134 (68.7%) of 195 evaluable patients, stabilized bone disease in 169 (86.7%) of 195 patients at week 12, and responses in soft tissue lesions in 22 (36.7%) of 60 patients. No obvious dose-related activity benefits were found. As of Sep 26, 2019, the median time to PSA progression was 36 weeks (95% CI 24−47), while that to radiological progression was 73 weeks (95% CI 49−96). As expected, patients without previous chemotherapy showed relatively longer time to PSA and radiological progression than those with previous chemotherapy. Conclusions: SHR3680 is safe and well tolerated, and exhibits high efficacy in mCRPC patients. Clinical trial information: NCT02691975.

Dose-escalation results of a phase I study of 225Ac-J591 for progressive metastatic castration resistant prostate cancer (mCRPC).

114 Background: Prostate-specific membrane antigen (PSMA) can be targeted by antibodies (Ab) or small molecule ligands labeled with potent α emitters (e.g. 225Ac). Unlike ligands, Ab biodistribution does not include non-tumor organs such as the salivary glands, kidneys and small bowel. We performed a phase I single ascending dose Ab study. Methods: Eligibility: progressive mCRPC following at least 1 potent AR pathway inhibitor (ARPI; e.g. abi/enza) and docetaxel (or unfit/refuse chemo) without limit of # prior therapies provided adequate organ function. Baseline 68Ga-PSMA11 PET was performed but not used for eligibility. Single-subject cohorts received a single infusion of 225Ac-J591 until grade (Gr) > 1 attributable toxicity or dose level 5, then transition to 3+3 design. Cohort 1 = 13.3 KBq/kg with planned escalation up to dose level 7 (93.3 KBq/kg). Dose-limiting toxicity (DLT) defined as attributable Gr 4 heme or Gr 3/4 non-heme toxicity. Results: 22 men were treated on 7 dose levels; median age 72.5 (range 58-89), PSA 146.5 (4.8-7168.4); 82% with >2 prior ARPI, 64% chemo, 45% sipuleucel-T, 23% radium-223, 55% prior 177Lu-PSMA. By standard imaging 82% bone, 36% lymph node, 9% liver mets. At the time of data cutoff, 1 of 6 men in cohort 6 (80 KBq/kg) had DLT (Gr 4 anemia and platelets); he had 4 prior cycles of 177Lu-PSMA. No other attributable Gr >2 non-hematologic or Gr >3 heme AE (including 0 of 6 at the highest dose level). Low Gr temporary AE’s include: 16 (73%) with fatigue, 11 (50%) pain, 11 (50%) nausea, 6 (27%) with xerostomia (5 of 6 with prior 177Lu-PSMA), 3 (14%) AST elevation. With follow-up ongoing, 60% with any PSA decline, 35% with >50% PSA decline. Of 10 with detectable baseline and 12-week CTC counts (CellSearch), 8 declined (45-100% decline); 5 (50%) with CTC count conversion. While PSMA uptake was not a prerequisite for treatment, all had some PSMA uptake on 68Ga-PSMA11 PET/CT; 64% with SUVmax >5x liver SUV, 14% 2.5x – 5x liver, and 23% with SUVmax 0-2.5x liver SUV. Conclusions: PSMA-targeted alpha-emitter 225Ac utilizing intact Ab J591 is well tolerated with early evidence of clinical activity in a pre-treated population, including the majority with prior 177Lu-PSMA. Clinical trial information: NCT03276572.

A multicenter, randomized, controlled phase II study: Efficacy and safety of PSMA-targeted radioligand therapy I-131-1095 (1095) plus enzalutamide (enza) in 18F-DCFPyL PSMA scan avid, metastatic castration-resistant prostate cancer (mCRPC) patients post-abiraterone (abi) progression (ARROW).

TPS260 Background: PSMA is a transmembrane glycoprotein expressed in normal human prostate epithelium at low levels, but highly upregulated in metastatic prostate cancer (PC). 18F-DCFPyL is a novel PSMA-targeted PET imaging agent that has shown highly promising diagnostic performance for detection of metastatic disease, with potential to identify disease amenable to theranostic targeting. 1095 is a novel PSMA-targeted small molecule that binds to the extracellular domain of PSMA selectively with high affinity. The complex is internalized, allowing the beta emitter, I-131, to kill PC cells. Methods: ARROW is an open-label, randomized (2:1) trial of enza plus 1095 or enza alone in pts with progressive mCRPC who previously received abi. ~120 pts (80: 1095 + enza; 40: enza alone) will be treated at ~40 sites in the US and Canada. Eligible male pts must be at least 18 yo with metastatic disease documented by bone scan or soft tissue lesions measurable per RECIST 1.1 on CT/MRI, be PSMA-avid as determined by 18F-DCFPyL PET/CT, have evidence of biochemical or radiographic progression on abi, and be ineligible for or refuse to receive chemotherapy. Pts will receive enza (prescribed per approved labeling) with or without 1095 (100 mCi dose, followed by up to 3 additional dose(s) administered at least 8 weeks apart, as determined by dosimetry evaluation and occurrence of dose-limiting events). The primary objective is to determine the efficacy of 1095 plus enza compared to enza alone, based on PSA response (confirmed PSA decline ≥50%) rate according to Prostate Cancer Clinical Trials Working Group 3 (PCWG3) criteria. Additional objectives include objective response rate based on PCWG3-modified RECIST 1.1, progression-free survival (PFS) defined as the first occurrence of radiographic progression (PCWG3-modified RECIST 1.1), unequivocal clinical progression, or death from any cause, duration of response, overall survival, and the safety and tolerability of 1095 radioligand therapy. Clinical trial information: NCT03939689.

A phase Ib/II open-label study of tazemetostat (TAZ) plus enzalutamide (E) or abiraterone/prednisone (A/P) in chemotherapy-naive patients (pts) with metastatic castration-resistant prostate cancer (mCRPC).

TPS255 Background: The histone methyltransferase EZH2 is overexpressed in many cancers. In prostate cancer (PC), EZH2 inhibition may reverse acquired resistance to androgen inhibitors (AIs). Pts may initially respond to AIs, but pts who progress have limited treatment options. In phase 2 trials, TAZ, a selective, orally bioavailable, investigative small molecule EZH2 inhibitor, has demonstrated encouraging objective responses in B-cell lymphomas and molecularly defined solid tumors and a favorable safety profile. In PC preclinical models, TAZ + E or A/P showed a greater reduction in tumor growth than either drug alone. This study will evaluate the safety and efficacy of TAZ + E or A/P vs E or A/P alone in mCRPC. Methods: This phase 1b/2 study will enroll pts ≥18 years with progressive mCRPC, with or without prior second-generation AI treatment, and no prior chemotherapy. Phase 1b will identify the recommended phase 2 dose (RP2D) of TAZ when combined with E (160 mg/day) or A/P (A: 1000 mg/day; P: 5 mg twice-daily [BID]) and evaluate the safety and tolerability of each combination in treatment-naïve pts and pts previously treated with a second-generation AI. Using a modified 3+3 design (up to 48 pts: 18 for TAZ+A/P and 30 for TAZ+E), TAZ dosing will start at 400 mg BID, escalating to 800 mg BID in the TAZ+A/P group or 1600 mg BID in the TAZ + E group, if no dose-limiting toxicities are observed. Phase 2 will begin once the RP2D for each combination is determined. Efficacy and safety results from phase 1b will inform the final design for phase 2. Phase 2 will be an open label study where pts will be randomized to either E or A/P alone or in combination with TAZ. TAZ will be administered at the RP2D in continuous 28-day cycles for as long as pts tolerate treatment and continue AI therapy. Tumor assessments will be performed every 9 weeks for 6 months and every 12 weeks thereafter. Efficacy assessments include radiographic progression-free survival (primary endpoint), prostate-specific antigen (PSA) ≥50% response rate, time to PSA progression, time to subsequent systemic therapy, and objective response rate. Safety is a secondary endpoint.

TALAPRO-1: A phase II study of talazoparib (TALA) in men with DNA damage repair mutations (DDRmut) and metastatic castration-resistant prostate cancer (mCRPC)—First interim analysis (IA).

119 Background: Phase 2 and 3 studies with poly(ADP-ribose) polymerase inhibitors (PARPi) have demonstrated antitumor activity in patients (pts) with mCRPC with DDRmut who were previously treated with novel hormonal therapy (NHT). We report the first IA of a Phase 2 study of TALA, a potent inhibitor and trapper of PARP. Methods: TALAPRO-1 (NCT03148795) is enrolling pts (N ≈ 100) with measurable soft tissue disease, progressive mCRPC, and DDRmut likely to sensitize to PARPi (including ATM, ATR, BRCA1, BRCA2, CHEK2, FANCA, MLH1, MRE11A, NBN, PALB2, RAD51C), who received 1–2 chemotherapy regimens (≥1 taxane-based) and progressed on ≥1 NHT (enzalutamide/abiraterone acetate). Pts receive oral TALA 1 mg/d (moderate renal impairment, 0.75 mg/d) until radiographic progression, unacceptable toxicity, or consent withdrawal. Primary endpoint is objective response rate (ORR; blinded independent review). Secondary endpoints are time to OR, duration of response, prostate-specific antigen (PSA) decrease ≥50%, circulating tumor cell (CTC) count conversion (to CTC = 0 and <5 per 7.5 mL of blood), time to PSA progression, radiographic progression-free survival (rPFS), overall survival, safety, pt-reported outcomes, and pharmacokinetics. A planned IA of safety and efficacy was performed after 20 pts with BRCA1/2 mutations were on treatment for ≥8 wks. Results: 81 pts received TALA as of June 5, 2019; 43 pts enrolled by Feb 12, 2019 were evaluable for the primary endpoint (20 BRCA1/2, 2 PALB2, 14 ATM, 7 other). All had received docetaxel and 49% prior cabazitaxel. Overall ORR (95% CI) was 25.6% (13.5–41.2), ORRBRCA1/2 50.0% (27.2–72.8), ORRATM 7.1% (0.2–33.9). Overall median (95% CI) rPFS was 5.6 months (mo) (3.5–8.2), rPFSBRCA1/2 8.2 mo (5.6–NE), rPFSATM 3.5 mo (1.7–8.1). Most common treatment-emergent adverse events (≥20%) were anemia, nausea, asthenia, decreased appetite, constipation, and platelet count decreased. Conclusions: TALA monotherapy demonstrates encouraging antitumor activity in docetaxel-pretreated mCRPC pts, especially those with BRCA1/2mut, and was generally well tolerated. This study was sponsored by Pfizer Inc. Clinical trial information: NCT03148795.

Dosimetry of 177Lu-PSMA-617 for the treatment of metastatic castration-resistant prostate cancer: A sub-study of the VISION trial.

TPS265 Background: Prostate-specific membrane antigen-617 labelled with lutetium-177 (177Lu-PSMA-617) is a promising treatment for patients with metastatic castration-resistant prostate cancer (mCRPC) after treatment with taxane chemotherapy and a novel androgen axis inhibitor. The radiotherapeutic molecule has high PSMA binding affinity, prolonged tumor retention with a rapid kidney clearance, and high tumor-to-background ratio, delivering therapeutically relevant doses of radiation to prostate cancer lesions. A randomized, prospective phase 3 trial to assess the efficacy of 177Lu-PSMA-617 in patients with progressive PSMA-positive mCRPC is ongoing (VISION trial, NCT03511664). However, as with other targeted radionuclide treatment modalities, there may be a risk of radiotoxicity to normal organs. Therefore, estimation of absorbed doses in these organs in a representative manner within the framework of such a study is essential. Methods: As a substudy of the VISION trial, extensive intratherapeutic dosimetry will be performed in a group of 30 patients at four participating German sites. Patients will undergo planar whole-body scintigraphy scans and single-photon emission computed tomography/computerized tomography (SPECT/CT) scans of the upper and lower abdomen at approximately 2, 24, and 48 hours, and 7 days after administration, along with blood sampling and urine collection. SPECT/CT data will be quantitatively reconstructed and a standardized calibration procedure of the imaging and measurement equipment used (SPECT/CT, dose calibrator, well counter) will be performed at all sites according to European Association of Nuclear Medicine (EANM) and Medical International Radiation Dose (MIRD) guidelines [1]. Organ masses will be measured for each patient using CT imaging, if accessible. Absorbed doses for kidneys, liver, spleen, salivary and lacrimal glands, and bone marrow, as well as prostate cancer lesions, will be calculated for each patient following international guidelines [2,3].

ModraDoc006, an oral docetaxel formulation in combination with ritonavir (ModraDoc006/r), in metastasized castration-resistant prostate cancer (mCRPC): A multicenter phase I study.

79 Background: ModraDoc006 is a novel formulation of docetaxel and to enhance bioavailability, this tablet is co-administered with ritonavir (r), an inhibitor of cytochrome p450 3A4 and P-glycoprotein. The safety, anti-tumor activity and pharmacokinetics (PK) of ModraDoc006/r were investigated by dose-escalation in patients with mCRPC, to propose a recommended phase 2 dose (RP2D). Methods: Progressive mCRPC patients, who were treatment naïve or previously treated with either abiraterone or enzalutamide, received a maximum of 30 weekly cycles of ModraDoc006/r in a bi-daily once weekly (BIDW) schedule. Plasma docetaxel concentrations were determined at the first 2 cycles up to 48h after intake of ModraDoc006/r. Adverse events were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.03. Serum Prostate Specific Antigen (PSA) levels were assessed every 6 weeks. Results: 23 patients were included, of whom 20 were evaluable for safety and PK. In 5 patients, the initial 30-20/100-100 dose was explored, with observation of one dose limiting toxicity (DLT) (grade 3 alanine aminotransferase increase). The next dose level of 30-20/200-200 resulted in 2 DLTs in 6 patients (grade 3 diarrhea and mucositis). Subsequently, two intermediate dose levels: 30-20/200-100 and 20-20/200-100 were explored in 6 and 3 patients. At the 30-20/200-100 dose, an adequate docetaxel exposure was achieved and 1 DLT (grade 3 diarrhea) was observed, with no DLTs at the 20-20/200-100 dose. Common treatment-related AEs (occurring in > 30% of all patients) were diarrhea, nausea, vomiting, anorexia and fatigue. Five patients completed the maximum of 30 weekly treatments. In 10 patients, evaluable for anti-tumor activity after treatment with ≥9 cycles, 4 confirmed and 2 non-confirmed PSA responses ( > 50% decrease) were observed. Conclusions: The RP2D of BIDW ModraDoc006/r in mCRPC was established as 30-20/200-100 mg. These results are encouraging for further development of ModraDoc006/r as a convenient, safe and effective alternative to IV docetaxel for mCRPC patients. A phase 2b study is currently being conducted. Clinical trial information: NCT03136640.

Results of a phase I/II prospective dose-escalation trial evaluating safety and efficacy of combination 177LuPSMA-617 and NOX66 in men with mCRPC post androgen signalling inhibition and two lines of taxane chemotherapy (LuPIN trial).

120 Background: Despite treatment advances, metastatic castrate resistant prostate cancer (mCRPC) remains a lethal disease. Trials in 177LuPSMA-617 have demonstrated good efficacy and safety, but synergistic combinations may further improve treatment responses. NOX66 inhibits external NADH oxidase type 2 with downstream pro-apoptotic actions including radio-sensitization. We present results of a prospective open label single arm phase 1/2 dose escalation/expansion trial of 177LuPSMA-617 and NOX66 in mCRPC. Methods: Men with progressive mCRPC post androgen signalling inhibition (ASI) and taxane chemotherapy were eligible. Inclusion criteria included PSMA PET/CT intensity > SUV max 15, with no discordant disease on FDG PET/CT, Hb > 100 g/L, Platelets > 90 x 106/L and GFR > 40 mL/min. Protocol allowed up to 6 doses of 177 Lu-PSMA 617 (7.5Gbq) on day 1 with NOX66 (suppository) given day 1-10 at 6-weekly intervals; the first 8 men received 400mg NOX66. After safety review, dose was escalated to 800mg. Data regarding safety, efficacy, pain scores, and QOL were collected. Results: 32/43 (26% imaging screen failures) screened men were enrolled (November 2017 – June 2019), of whom 100% had prior docetaxel and ASI, and 94% (30/32) cabazitaxel. All men received ≥ 2 cycles, with 12/32 completing 6 cycles, and 16/32 2 - 5 cycles, while 4/32 remain on treatment. Any PSA response was seen in 84% (27/32), with a PSA response > 50% in 62.5% (20/32). Median PSA PFS was 6.5 months (95%CI 3.54-9.3). To date, 72% (23/32) of patients have progressed. 34% (11/32) men have died with median OS not reached. 50% (12/24) of men with baseline pain scores ≥3 (24/32) had significant reduction in pain. Adverse events are summarized below. Conclusions: Combination 177LuPSMA-617 with NOX66 appears safe and efficacious in men with heavily pre-treated mCRPC. Clinical trial information: ACTRN12618001073291. [Table: see text]

Therapeutic efficacy, prognostic variables and clinical outcome of 177Lu-PSMA-617 PRLT in progressive mCRPC following multiple lines of treatment: prognostic implications of high FDG uptake on dual tracer PET-CT vis-à-vis Gleason score in such cohort.

To evaluate the therapeutic response, progression free survival (PFS), overall survival (OS) and clinical toxicity of 177Lu-PSMA-617 PSMA targeted radioligand therapy (PRLT) in the setting of heavily pre-treated metastatic castrate-resistant prostate cancer (mCPRC) patients and also examine the association of prognostic variables with therapeutic outcome in such patient cohort. We examined the medical records of mCRPC patients who had undergone 177Lu-PSMA-617 PRLT from March 2017 to February 2019 in our institute. Patients receiving equal to or more than two cycles were included and analyzed in this retroprospective study.The 68Ga-PSMA-11 PET-CT and 18-fludeoxyglucose positron emission tomography (18FDG PET)-CT scan findings, serum prostate-specific antigen (PSA) change, health-related quality of life (HRQoL) scales (Eastern Cooperative Oncology Group/Karnofsky score) and Gleason score were assessed for their implications on the outcome of therapy. The treatment response was evaluated under three categories: (a) symptomatic (b) biochemical and (c) imaging response.The PFS and OS following first PRLT were determined and the association of various variables with PSA doubling time (DT) and FDG uptake in the lesions were analyzed. Toxicity assessment was undertaken objectively by National Cancer Institute-Common Terminology Criteria for Adverse Events scale v. 5.0 for haematological and nephrotoxicity, and salivary gland toxicity assessed by xerostomia inventory score. A total of 40 mCRPC patients (age range: 46-84 years; median 63 years), who had undergone 177Lu-PSMA-617 PRLT, of at least two cycles was identified and selected for the analysis. FDG uptake was noted in 87.5% of patients (n = 35). Out of 40 cases, 21 were responders (CR, PR and SD) and 19 were non-responders (PD) on symptomatic and biochemical scales while on molecular imaging response, 16 (43%) were responders and remaining 21 (57%) were non-responders. Lesion-wise, 68Ga-PSMA-11 avid metastatic nodal disease responded well with 177Lu PSMA-617 PRLT, as compared to hepatic and skeletal lesions. The median OS and PFS was 12 and 7 months respectively following first PRLT. Patients with negative serum PSA-DT demonstrated superior 1 year PFS as compared to those with positive serum PSA-DT (52.5 vs 47.5%) (p = 0.029). Patients receiving greater than two cycles PRLT demonstrated a higher negative PSA-DT as compared to those receiving two cycles (p-value = 0.03). Grade 1 xerostomia was observed in two patients (5%) (mean xerostomia score of 23), haematotoxicity in seven patients [Grade I (n = 2, 5%) and Grade II (n = 5, 14%)]. 177Lu-PSMA-617 PRLT was well-tolerated and able to produce disease control with good symptomatic and biochemical responses in the context of heavily pre-treated mCRPC with progressive disease, with low toxicity profile. Evident association of high FDG uptake was observed with aggressive disease biology coupled with increasing Gleason score and poorer 12 months PFS. Negative PSA-DT following therapy demonstrated longer PFS. The results demonstrate important future role of 177Lu-PSMA-617 PRLT in the treatment of mCRPC. The present work explored in a large teriary cancer care setting, the efficacy of 177Lu-PSMA-617 PRLT, in an aggressive and unselected subset of mCRPC. The response and outcome was correlated with a number of prognostic variables, including molecular imaging findings (FDG uptake in the metastatic lesions), PSA DT and Gleason score.

849PD - Preliminary results of a phase I/II dose-escalation study of fractionated dose 177Lu-PSMA-617 for progressive metastatic castration resistant prostate cancer (mCRPC)

BackgroundPSMA is overexpressed in PC with limited expression in other organs. PC is radiosensitive with dose-response. Dose-fractionation allows delivery of higher total dose per cycle, may result in less radioresistance due to repopulation compared with doses 6-12 wks apart. Initial Ph I safety results of the dose-escalation portion of this study [ESMO 2018] were without DLT at all dose levels. MethodsEntry criteria: progressive mCRPC following at least 1 potent AR-targeted agent (e.g. abi/enza) and taxane (or unfit/refuse chemo) without limit of # prior therapies, adequate organ function, ECOG performance status 0-2. No preselection for PSMA expression. Treatment was a single cycle of fractionated dose 177Lu-PSMA-617 on D1 and D15. In the Ph I dose-escalation cohort, men received 7.4 to 22 GBq. In Ph II, a Simon 2 stage design enrolled pts at the 22.2 GBq dose level. Pre- and post-treatment 68Ga-PSMA11 PET/CT and post-treatment 177Lu-PSMA-617 imaging was performed in addition to standard serial CT and bone scans. Cellsearch CTC count at baseline and 12 wks. Results44 men (29 in Ph I, 15 in Ph II; total 21 at 22.2 GBq) with median age 69 (range 55-91), median PSA 182.97 (range 0.89-5541) were treated. 93% with bone, 45% nodal, 18% lung, 9% liver, 9% other visceral metastases. 55% with at least 1 prior chemo regimen, 52% >1 prior potent AR therapy, 27% with Ra223, 30% sip-T, 5% 177Lu-J591; 66% Halabi poor risk, 30% intermed risk. With follow up ongoing, 61% with >50% PSA decline (71.4% at 22.2 GBq), median overall survival 16 months (95% CI 11-NR). Of 26 with paired CTC counts, 57.7% decreased, 7.7% stable, 34.6% increased; 34.6% converted from detectable to undetectable at 12 weeks). 61.4% with all grade xerostomia, 29.5% fatigue, 25% thrombocytopenia, 25% anemia, 25% pain, 15.5% nausea. While not required for eligibility, all pts had some PSMA uptake in at least 1 site on PSMA PET, with 2.2% highest lesion SUV < liver SUV, 4.5% 1-2.5x, 13.6% 2.5-5x, and 79.5% highest lesion SUV > 5x liver. ConclusionsA single fractionated cycle of up to 22.2 GBq of 177Lu-PSMA-617 is safe, with encouraging early efficacy signals, even without selection for PSMA expression by imaging. A trend for dose-response was observed. Clinical trial identificationNCT03042468. Legal entity responsible for the studyWell Cornell Medicine. FundingWeill Cornell Medicine, Prostate Cancer Foundation, US Department of Defense, US National Institutes of Health, Endocyte. DisclosureS.T. Tagawa: Advisory / Consultancy, Research grant / Funding (institution): Endocyte. H. Beltran: Advisory / Consultancy: Endocyte. S. Vallabhajosula: Research grant / Funding (institution): Endocyte; Full / Part-time employment: NCM USA. O. Sartor: Research grant / Funding (institution): Endocyte. All other authors have declared no conflicts of interest.

885P - Spatial-temporal change in quantitative total bone imaging (QTBI) and circulating tumour cells (CTCs) in metastatic castration-resistant prostate cancer (mCRPC) treated with enzalutamide (ENZA)

885P - Spatial-temporal change in quantitative total bone imaging (QTBI) and circulating tumour cells (CTCs) in metastatic castration-resistant prostate cancer (mCRPC) treated with enzalutamide (ENZA)

Renal outcomes of radioligand therapy: experience of 177lutetium-prostate-specific membrane antigen ligand therapy in metastatic castrate-resistant prostate cancer.

BackgroundRadioligand therapy (RLT) with 177lutetium (Lu)-labelled prostate-specific membrane antigen (PSMA) ligands has been increasingly used in recent years for therapy of metastatic castrate-resistant prostate cancer (mCRPC). Studies have revealed that 177Lu-PSMA ligand therapy is well tolerated and appears to cause fewer adverse effects than current standard of care third-line treatments. Notably, since 177Lu-PSMA agents are predominantly excreted by kidneys, there are concerns relating to their potential nephrotoxicity and renal outcomes. Although many recent studies have focused on mostly nephrotoxic adverse reactions at up to 3-month follow-up, assessment of renal outcomes after 177Lu-PSMA RLT in longer term follow-up is lacking. The aim of this study was to assess the influence of 177Lu-PSMA RLT on renal function in patients treated for mCRPC at >3 months post-therapy.MethodsIn this retrospective cohort study, we assessed 195 men with progressive mCRPC who had received therapy with 177Lu-PSMA as second- or third-line after standard therapeutic interventions. Patients underwent investigations with 68Ga-PSMA-ligand positron emission tomography/computed tomography scan to confirm PSMA-expressing mCRPC. Eligible patients were required to have estimated glomerular filtration rate (eGFR) >30 mL/min/1.73 m2, an Eastern Cooperative Oncology Group performance status score <3, no severe liver injury (as characterized by liver function tests) and no significant bone marrow dysfunction. Enrolled patients received two to five cycles of intravenous 177Lu-PSMA I&T or 177Lu-PSMA-617, at 6- to 10-week intervals. Renal outcomes were assessed according to Kidney Disease: Improving Global Outcomes guidelines as incidence of acute kidney injury (AKI), acute kidney disease (AKD) or chronic kidney disease (CKD). All assessments and tests were undertaken between therapy cycles and at follow-up of at least 3 months.ResultsOf 195 assessed men with mCRPC, 110 patients aged [mean ± SD (range)] 70 ± 8 (53–92) years were recruited into this study with median follow-up of 8 (interquartile range 5–12, minimum 3, maximum 29) months and mean baseline eGFR 81 ± 13 mL/min/1.73 m2. Pre-existing CKD was identified in 12% of patients. None of the patients experienced an AKI during RLT. Two AKD and three CKD G3a cases were identified. Analysis of possible impact of prior CKD and major risk factors (hypertension, diabetes, history of AKI) on incidence of AKD or CKD demonstrated relative risk 4.2 [95% confidence interval (CI) 1.23–14.29] and 1.91 (95% CI 1.14–3.12), respectively. However, Fisher’s exact test did not reveal statistical significance of the impact of both conditions.ConclusionsCurrent Lu-PSMA RLT protocols appear to carry a mild nephrotoxic risk with the rate of about 4.5%. Prior CKD is potentially the most significant risk factor of post-RLT renal dysfunction.

Abstract 1348: Characterization of SLFN11 protein expression in circulating tumor cells (CTCs) of patients with metastatic castration resistant prostate cancer (mCRPC) prior to platinum based chemotherapy

Abstract Background: Clinical benefit in response to chemotherapeutic agents that induce replication stress such as PARP inhibitors and cisplatin has been associated with mutations in DNA damage repair (DDR) genes. However, prediction of benefit is not solely explained by DDR mutations; therefore, additional biomarkers for prediction of clinical benefit of these agents are needed. SLFN11 is recruited to stalled replication forks where it sensitizes cells to DNA damage induced replication stress . Presence of SLFN11 protein expression in tumor cells is related to pre-clinical and clinical benefit of PARPi in small cell lung cancer. Previously, we reported high cellular heterogeneity in progressive mCRPC, and as such, we sought to examine whether SLFN11 protein expression was expressed in patients offered platinum chemotherapy to understand the subclonal heterogeneity of CTCs with and without SLFN11 protein expression. Material and methods: 30 blood samples from mCRPC patients prior to treatment with a platinum chemotherapy from MSKCC were sent to Epic Sciences for CTC enumeration and SLFN11 protein expression characterization. Nuclear localization of SLFN11 was reviewed by a trained technician. 70 CTCs from patients with and without SLFN11 CTCs were single cell sequenced and analyzed for copy number alterations (CNA) and clonality. Results: 83% (25/30) of patient samples had detectable CTCs, and 53% (16/30) samples had at least one SLFN11+ CTC. For patients with SLFN11(+) CTCs, 81% (13/16) had only nuclear localized SLFN11 expression; 6% (1/16) had a mix of CTCs with nuclear and non-nuclear localized SLFN11 expression; 13% (2/16) had no nuclear localized SLFN11 expression. In 13 patients with exclusively nuclear localized SLFN11 expression, the % of SLFN11(+) CTCs ranged from 2-100% with median of 11%. Single CTC NGS analysis of patients demonstrated genomic heterogeneity between CTCs. In patients with both SLFN11+ and SLFN11- CTCs, no discernable clonal or CNA difference was observed between SLFN11+ and SLFN11- CTCs. Conclusions: SLFN11 protein expression was observed subclonally in a majority fraction of patients with progressive mCRPC prior to platinum chemotherapy. SLFN11 expression heterogeneity was not consistent with a genetic mechanism. Studies examining whether SLFN11+ CTCs as a sensitivity marker to PARPi &amp; cisplatin, but not ARSi or taxanes in mCRPC are ongoing. Citation Format: Luisa Fernandez, John Poirier, Angel Rodriguez, Melanie Hulling, Robin Richardson, Ramsay Sutton, Rhett Jiles, Joseph Schonhoft, Jerry Lee, Nadia Ebrahim, Emily Carbone, Ethan Barnett, Mark Landers, Yipeng Wang, Ryan Dittamore, Charles Rudin, Howard Scher. Characterization of SLFN11 protein expression in circulating tumor cells (CTCs) of patients with metastatic castration resistant prostate cancer (mCRPC) prior to platinum based chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1348.

Abstract CT097: Phase I trial of apalutamide plus abiraterone acetate, docetaxel, and prednisone in patients with metastatic castration-resistant prostate cancer (mCRPC)

Abstract Background: Prostate cancer is driven by the androgen receptor (AR) pathway, which may be targeted by inhibition of androgen synthesis (e.g. abiraterone = Abi), AR signaling (e.g. apalutmide = Apa), and/or translocation of AR to the nucleus (e.g. docetaxel = Doce). The combination of AR inhibition plus taxane chemotherapy has already demonstrated clinical benefit (CHAARTED, STAMPEDE), lending weight to the theory that combining drugs targeting different points in the AR signaling pathway is effective. We hypothesize that the combination of Apa, Abi, and Doce will be safe and efficacious. Methods: Men with progressive mCRPC, intact organ function, and no prior exposure to Apa (ever) or Doce within 3 years were enrolled. Standard Abi 1000 mg daily, Doce 75 mg/m2 q3 weeks, and prednisone 5 mg BID was administered with different doses of Apa. Cohort 1 = Apa 120 mg daily, Cohort 2 = Apa 240 mg daily, Cohort 3 (if necessary) = Apa 180 mg daily in modified 3+3 design. The primary endpoint of the Phase I dose-escalation portion of the study was determination of dose-limiting toxicity (over 6 weeks) and recommended Phase II dose (RP2D). Results: Nine men (3 Apa 120 mg, 6 Apa 240 mg) with mCRPC and median age 69, median PSA 8.18 (range 0.07 - 278.5) were treated. 67% with bone, 78% LN, 11% lung, 11% other metastases. No DLT occurred with Apa 120 mg and 1 of 6 with Apa 240 mg had possibly related grade 3 hypertension. All had &amp;gt;95% PSA decline (78% with &amp;gt; 99% decline). Of 5 with measureable disease, 100% had RECIST response. 6 of 7 with post-treatment CTC counts were undetectable. Conclusions: The combination of apalutamide plus abiraterone, docetaxel, and prednisone at full doses is tolerable, with the RP2D of the regimen Apa 240 mg daily, Abi 1000 mg daily, docetaxel 75 mg/m2 q3 wks, and prednisone 5 mg BID. The combination appears to be associated with a high rate of PSA decline, measurable disease response, and CTC count control. Tumor tissue, plasma ctDNA, and CTCs are being collected for analysis. Enrollment to the expansion phase of study to further refine efficacy and toxicity at PCCTC sites is ongoing including assessment of response and resistance biomarkers [NCT02913196] Citation Format: Ana Molina, Paul Christos, Amy Hackett, Luke Nordquist, Edward Gelmann, Mark Stein, Cora Sternberg, Himisha Beltran, Lauren Gracey, Giuseppe Galletti, Paraskevi Giannakakou, David M. Nanus, Scott T. Tagawa. Phase I trial of apalutamide plus abiraterone acetate, docetaxel, and prednisone in patients with metastatic castration-resistant prostate cancer (mCRPC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT097.

Abstract CT095: A Phase Ib/IIa study of the BET bromodomain inhibitor ZEN-3694 in combination with enzalutamide in patients with metastatic castration-resistant prostate cancer (mCRPC)

Abstract Background: Abiraterone (ABI) and enzalutamide (ENZ) have significant activity in mCRPC yet demonstrate frequent cross-resistance limiting efficacy of sequential androgen receptor (AR) targeting. Bromodomain extra terminal (BET) inhibitors (BETi) down-regulate the expression of putative drivers of ABI/ENZ resistance. ZEN-3694 is an orally bioavailable, potent, and selective BETi with significant anti-tumor activity in ENZ-resistant pre-clinical models. The safety and efficacy of ZEN-3694 in combination with ENZ was evaluated in a phase 1b/2a study in mCRPC (NCT02711956). Methods: Patients (pts) were required to have progressive mCRPC, prior resistance to ABI and/or ENZ, and no prior chemotherapy for mCRPC. A 3 plus 3 dose escalation schema was utilized, with a starting daily oral dose of ZEN-3694 36 mg plus ENZ 160 mg. Dose expansion was conducted in parallel cohorts at low and high-dose ZEN-3694 (48 and 96 mg daily, respectively). The primary objective was determination of maximally tolerated dose (MTD); key secondary endpoints included time to radiographic progression (TTP) and pharmacokinetic (PK) parameters. Pharmacodynamic (PD) markers included whole blood RNA expression of BETi targets including MYC, IL-8, CCR1, and IL1RN. Results: 64 pts were enrolled. The median age and PSA at study entry was 70 (range 47 - 89) and 25.9 (range 0.1 - 1701.8), respectively. At study entry, 24 (37.5%) of pts were resistant to ABI, 29 (45.3%) were resistant to ENZ, and 11 (17.2%) to both. ZEN-3694 dose levels ranged from 36 mg to 144 mg daily without reaching a MTD. The most common treatment-related adverse events (AEs) (any grade) included transient photophobia (66%), nausea (40%), fatigue (31%), decreased appetite (22%), and dysgeusia (16%). Grade ≥ 3 related AEs (N = 8) and dose-limiting toxicities (N = 1 at 96 mg dose level) were uncommon. No Grade ≥ 3 thrombocytopenia was observed. Exposure to ZEN-3694 increased with dose without significant drug-drug interaction with ENZ. PD analyses demonstrated exposure-dependent, up to 4-fold decrease in expression of BETi targets. RNA-Seq of paired tumor biopsies demonstrated suppression of BET-dependent genes. The overall median TTP was 44.4 weeks, and was similar in subgroups with prior ABI vs. ENZ resistance. Durable responses were observed, including 3 pts with disease primarily refractory to ABI on study treatment for 21.3 +, 20.8 +, and 17.3 months, respectively, with &amp;gt; 90% decline in serum PSA. Early transitory serum PSA increases were associated with longer TTP. Conclusions: ZEN-3694 demonstrates an acceptable safety and PK profile, robust target modulation, and encouraging disease stabilization in combination with ENZ in ABI/ENZ-refractory mCRPC. Analysis of paired metastatic tumor biopsies, circulating tumor cells and ctDNA is ongoing. Further investigation of the combination is warranted. Citation Format: Rahul Aggarwal, Wassim Abida, Michael Schweizer, Allan Pantuck, David Nanus, Elisabeth Heath, Sanjay Lakhotia, Henrik Hansen, Michael Silverman, Lisa Bauman, Margo Snyder, Eric Campeau, Karen Norek, Sarah Attwell, Marie O'Farrell, Steve Smith, Philip Wegge, Ravi Jahagirdar, Joshi Alumkal. A Phase Ib/IIa study of the BET bromodomain inhibitor ZEN-3694 in combination with enzalutamide in patients with metastatic castration-resistant prostate cancer (mCRPC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT095.

Abstract 2294: Plasma progastrin level as a predictive and prognostic biomarker in advanced prostate cancer

Abstract Background and Aims: Progastrin is a tumor promoting peptide which is detectable in the blood of patients with different cancers. Progastrin gene is a direct target of the WNT/ß-catenin oncogenic pathway involved in tumorigenesis and possibly tumor progression/ treatment efficacy. Since WNT/ß-catenin oncogenic pathway is dysregulated in advanced prostate cancer we evaluated plasma progastrin in metastatic prostate cancer as a predictive and prognostic biomarker. Methods: Metastatic hormone sensitive prostate cancer (mHSPC) and metastatic castration resistant prostate cancer (mCRPC) states were enrolled in a cohort study of blood sample collection and follow-up for outcomes between 9/2009 and 11/2013. Patients were enrolled in mHSPC unique sub-cohorts before initiating androgen deprivation therapy (ADT); during ADT; at the time of failure of ADT and before starting chemotherapy. Plasma progastrin was measured using the ELISA cancerREAD®. Progastrin concentrations in the cancer patients (test set) was assessed against 213 samples from asymptomatic volunteers from the French blood establishment (control set) and prograstin levels were also compared for each of the above four mHSPC and mCRPC cohorts as well as for association with time to failure on AA for the mHSPC cohort and overall survival for both mHSPC and mCRPC subcohorts. We also determined progastrin levels in patients with two serial samples to evaluate if changes were predictive for overall survival. Results: Of the 523 mHSPC+mCRPC patients 96 were in mHSPC state enrolled before starting ADT; 101 mHSPC patients were enrolled while receiving ADT; 143 mHSPC patients were enrolled at the time of ADT failure and 143 were clinically progressive mCRPC. All cohorts were unique and 246/523 patients had two serial samples collected and analyzed across all subcohorts. The median time of follow up of the whole cohort was 8.34 years (IQR: 4.53-12.97) and 371/523 had died at the time of the analysis. Plasma progastrin levels was detected in 87.6% of all the patients (cut-off value 1 pM, range 0 to 311 pM, median value of 4.7 pM) compared to the control set (median value=0.61 pM; IQR 0.00-1.58). The Receiver Operating Characteristic analysis indicated an area under the curve of 0.84 (p&amp;lt;0.0001; 95% CI 0.81 to 0.87). Of these, 106 patients had a decrease and 140 patients an increase of progastrin levels. Patients with a serial increase of progastrin had a worst overall survival compare to the other group (p=0.019). Conclusion: Progastrin is a blood based biomarker elevated in advanced prostate cancer patients serial increases in progastrin levels during treatment are predictive of poor survival. Progastrin assay might be useful for monitoring therapeutic interventions like androgen deprivation therapy effects as well for advanced prostate cancer patients. Citation Format: Manish Kohli, Winston Tan, Lea Payen, Carole Langlois-Jacques, Pierre Liaud, Delphine Maucort-Boulch, Dominique Joubert, Alexandre Prieur. Plasma progastrin level as a predictive and prognostic biomarker in advanced prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2294.

RESIST-PC phase 2 trial: 177Lu-PSMA-617 radionuclide therapy for metastatic castrate-resistant prostate cancer.

5028 Background: This is an investigator-initiated open-label prospective bi-centric single-arm phase 2 clinical trial (NCT03042312) of 177Lu-PSMA-617 radionuclide therapy in patients with progressive metastatic castrate-resistant prostate cancer (mCRPC). Methods: Patients with progressive mCRPC (biochemical, radiographic or clinical) after ≥1 novel androgen axis drug (NAAD), either chemotherapy (CTX) naïve or post-CTX, with sufficient bone marrow reserve and normal kidney function were eligible. All patients underwent a screening PSMA PET/CT to confirm target expression. Patients received up to 4 cycles of 177Lu-PSMA-617 every 8±1 weeks and were randomized into 2 treatment activities groups (6.0 or 7.4 GBq). Kidney dosimetry was performed for the first cycle. Efficacy was defined as serum PSA decline of ≥50% from baseline at 12 weeks and served as primary endpoint. Results: 64 patients (median PSA 75 ng/ml; range 0.5-2425) were included in the study. 20% were CTX naïve while 80% were post-CTX (1.9 CTX regimens on average, range 1-4). 45% completed 4 cycles of 177Lu-PSMA-617. Androgen deprivation therapy was given concomitantly in 83%, NAAD in 23% and immunotherapy in 6%. PSA decline of ≥50% was observed in 23% of patients at 12 weeks and in 38% of patients at any time (best PSA response). The median time to best PSA response was 22 weeks (range 6-49 weeks). 16% had a PSA decline of ≥90% and 59% had any PSA decline ( &gt; 0%). Mild and transient (CTCAE grade 1-2) side effects included xerostomia (72%), nausea/vomiting (69%) and bowel movement disorders (45%). CTCAE grade 3 toxicity included nausea/vomiting (6%), anemia (8%), leukopenia (5%), kidney failure (3%), thrombocytopenia (3%), and neutropenia (3%). The mean kidney dose was 2.7 Gy for the first cycle (range 0.9-5.9) i.e. 0.4 Gy/GBq (range 0.15-0.9). There was no difference between the efficacy and toxicity for the 6.0 GBq (n = 23) and 7.4 GBq (n = 41) treatment arms. Conclusions: 177Lu-PSMA-617 radionuclide therapy is well tolerated in patients with progressive mCRPC. PSA declined by ≥50% in 38% of patients. The best PSA response rate occurred after 3 cycles. Updated data will be provided at the time of the conference. Clinical trial information: NCT03042312.

Safety and preliminary immunogenicity of JNJ-64041809, a live attenuated, double-deleted Listeria monocytogenes-based immunotherapy, in metastatic castration-resistant prostate cancer (mCRPC).

e16509 Background: The safety and immunogenicity of JNJ-64041809 (JNJ-809), a live attenuated, double-deleted Listeria monocytogenes (LADD- Lm)-based immunotherapy targeting relevant prostate cancer antigens, was evaluated in a phase 1, multicenter, open-label study in patients (pts) with mCRPC. Methods: Men aged ≥18 years with progressive mCRPC who had received ≥2 prior approved therapies were included. The recommended phase 2 dose (RP2D) and the safety and immunogenicity of JNJ-809 were evaluated. Dose-limiting toxicities (DLTs), adverse events (AEs), T cell response, tumor response, and JNJ-809 bacterial shedding profile were assessed at 2 dose levels, 1 x 108 and 1 x 109 colony forming units (CFU). Results: 26 pts (median age 66.5 years, White 96%) were enrolled (1 x 108 CFU, n = 6; 1 x 109 CFU, n = 20). Median duration of treatment was 2.5 months (range 0-9.7). No DLTs occurred and 1 x 109 CFU was selected as the RP2D. Most common AEs were chills (n = 24, 92%), pyrexia (n = 21, 81%), and fatigue (n = 16, 62%). Grade ≥3 AEs were reported in 18 (69%) pts and serious AEs in 7 (27%) pts including 1 pt with investigator-assessed treatment-related grade 3 intestinal obstruction. At 1 x 108 CFU, all pts had negative blood cultures. At 1 x 109 CFU, 6 pts had LADD- Lm-positive blood cultures on day 1; blood cultures on all subsequent days were negative. JNJ-809 transiently induced peripheral cytokines including interferon-γ, interleukin-10, and tumor necrosis factor-α. Of 7 evaluable pts (1 x 109 CFU), post-treatment T cell responses were demonstrated in 6 pts to the Listeria antigen LLO and in 5 pts to ≥1 of the 4 encoded tumor antigens. Best overall response was stable disease (SD) in 13/25 evaluable pts with SD ≥16 weeks in 4 pts. The study was terminated early as the data collected from 26 pts were considered sufficient to evaluate safety and immune responses. Conclusions: JNJ-809 has a manageable safety profile consistent with that of other LADD- Lm-based therapies. Observed activation of immune responses with monotherapy did not translate into clinical activity, and further development of JNJ-809 will likely require a combination approach. Clinical trial information: NCT02625857.