A phase 2 study of ibrutinib as neoadjuvant therapy in patients with localized prostate cancer

387

Background: Treatment of localized prostate cancer (PCa) with surgery or radiotherapy remains suboptimal with failure rates of 35-40%. Bruton’s Tyrosine Kinase (BTK) is seen elevated in PCa tissues compared to normal prostate tissue. Malignant B-cell density has been correlated with higher risk of aggressive PCa and mitigating that through the BTK has been proposed in mouse models. Ibrutinib is a potent BTK inhibitor which targets B-cell signaling pathways, has an established safety profile, and has been shown to inhibit in vivo prostate tumor growth pre-clinically. Therefore, we hypothesized that ibrutinib will augment anti-tumor immune responses through inhibiting tumor-intrinsic growth via blocking BTK B-cell signaling pathways, while also inducing favorable T-cell profiles in localized PCa. Methods: We performed a neoadjuvant clinical trial (NCT02643667) studying ibrutinib in PCa. Eligible patients had localized PCa with no prior treatment, and deemed suitable for undergoing a radical prostatectomy. Patients received 840mg/day oral ibrutinib for 28 days followed by a radical prostatectomy 7-12 days later. Patients were assessed 4 weeks after surgery. The primary objectives are to assess safety of ibrutinib and characterize B and T cell infiltration. Correlative pre- and post- treatment tissue and blood samples were collected; BTK and PD-L1 expression in tumor and immune-infiltrating immune cells will be examined, and BCR and TCR clonality and diversity will be evaluated. Results: 22 patients were registered and underwent treatment to date. 4 patients had early termination of ibrutinib treatment with 3 due to adverse effects and 1 due to discovery of surgically unresectable disease. A total of 21 of 22 patients received radical prostatectomies. There were no intra-operative complications attributed to ibrutinib. The treatment was generally well tolerated with 7.1% grade 3 treatment related adverse effects. 2% experienced a grade 4 treatment adverse effects of hepatic dysfunction. The most common grade 1-2 adverse effects were diarrhea (8.2%), fatigue (7.1%), and anemia (6.1%). The median follow-up time was 23.9 months. Median overall survival and median failure free survival have not been reached and the two-year milestone is 100%. Sample collection is complete and immune correlative analyses are ongoing. Safety/tolerability, clinical outcomes, and preliminary correlative data will be reported. Conclusions: This is the first clinical trial of ibrutinib in PCa, and lays the foundation for larger future studies. Clinical trial information: NCT02643667 .

A pilot trial of neoantigen DNA vaccine in combination with nivolumab/ipilimumab and prostvac in metastatic hormone-sensitive prostate cancer (mHSPC)

5068

Background: Treatment with immune checkpoint blockade (ICB) alone results in suboptimal response rates in prostate cancer. Prostvac-VF Tricom is a therapeutic vaccine that incorporates DNA for the shared self-antigen PSA. Personalized neoantigen vaccines based on specific mutated epitopes may have the ability to overcome immunoresistance seen with self-antigens. Even in low mutational burden tumors like prostate cancer, T cell responses against neoantigens have been correlated with favorable clinical outcomes. Thus, we hypothesized that the combination of shared antigen and neoantigen vaccines with dual ICB will induce robust immune responses and improve clinical outcomes. Methods: This Phase I clinical trial (NCT03532217) enrolled patients from 2018-2021. Eligible patients had histologically confirmed high risk mHSPC, must have completed a course of docetaxel and received continuous androgen deprivation therapy. Patients were treated with Prostvac-VF in combination with ipilimumab/nivolumab within 60 days of the last docetaxel dose. Then, patients were continued on monthly nivolumab with their personalized neoantigen vaccine administered via intramuscular electroporation. The primary objectives of this study were to assess the feasibility, safety/tolerability, and immune responses of this combination strategy. Key secondary objectives include failure free survival, milestone overall survival (OS), PSA responses, and radiographic progression free survival. Results: Nineteen patients were enrolled and treated on trial, and feasibility was shown with 15 (79%) receiving neoantigen vaccines. Four patients did not receive neoantigen vaccines (2 for progressive disease, 2 for ICB toxicity). Treatment was well-tolerated with only 2 (2.4%) grade 3 treatment related adverse events (TRAEs) of colitis, and no grade 4+ TRAEs. The common grade 1-2 TRAEs were diarrhea (10%), injection site reactions (10%), rash (7.4%), and fatigue (6%). Median follow-up to date is 22.6 (11.3-39.6) months, with median OS not yet reached and 2 year milestone OS of 75%. Six (31.5%) patients had PSA progression per PCWG2 criteria while on treatment, with the median time to PSA progression not yet reached for the total population. Increases in activation/co-stimulatory/co-inhibitory seen after treatment with Prostvac/ICB, suggest immune priming. Sample collection is complete and immune correlative analyses are ongoing. Final safety/tolerability and preliminary correlative and clinical outcomes will be reported. Conclusions: This is the first clinical trial evaluating the use of personalized neoantigen vaccines in a combination immunotherapeutic approach in mHSPC patients. Clinical trial information: NCT03532217.

A phase 1b clinical trial of cabozantinib (CABO) and abiraterone (ABI) with checkpoint inhibitor immunotherapy (CPI) in metastatic hormone-sensitive prostate cancer (mHSPC) (CABIOS Trial)

TPS214

Background: Multiple systemic therapies have resulted in improved overall survival (OS) for mHSPC, including several AR-targeted agents (ARTA) and docetaxel chemotherapy. However, patients (pts) with high volume de novo metastatic prostate cancer still only have an OS of approximately 50 months. Thus, more effective combination strategies for initial treatment of mHSPC are urgently needed. CABO, a multi-tyrosine kinase inhibitor (including MET, VEGFR-1, -2,-3, AXL) has shown synergy with ABI as well as with CPI in preclinical studies. CABO and ABI have demonstrated an acceptable safety profile in metastatic castration resistant prostate cancer (mCRPC) (Choudhury et al Prostate 2018), and CABO and atezolizumab (ATEZO) in combination have showed a promising efficacy signal and manageable safety profile in mCRPC (COSMIC-021, NCT03170960; Agarwal ESMO 2021). The phase 3 CONTACT-02 trial (NCT04446117) is randomizing mCRPC pts to either CABO and ATEZO or a second generation ARTA. Given the robust preclinical and emerging clinical data for the use of both CABO and CPI therapy in advanced prostate cancer and the need to optimize therapy earlier in the course of disease, in the present trial we intend to evaluate the safety and tolerability of ABI, CABO, and CPI in mHSPC. Methods: CABIOS (NCT04477512) is a phase Ib, single center, open label trial of ABI, CABO and the CPI nivolumab (NIVO), an anti-PD-1 monoclonal antibody, in pts with mHSPC. Key inclusion criteria include histologically or cytologically confirmed metastatic prostate adenocarcinoma without neuroendocrine/small cell differentiation and radiographic evidence of metastatic disease. Ongoing androgen deprivation (ADT) within 12 weeks of study start is allowed. Key exclusion criteria include evidence of castration resistance, prior treatment with second-generation androgen receptor inhibitors, CYP17 inhibitors, CABO, or checkpoint inhibitor immunotherapy (anti-PD-1/PD-L1, CTLA-4), active autoimmune disease, and ongoing treatment with systemic corticosteroids daily. The primary objective of the trial is evaluation of the safety and tolerability of this combination therapy in the trial population; the primary endpoint is the frequency of dose-limiting toxicities (DLTs) as measured by CTCAE v5.0. The study will employ a 3 + 3 design evaluating ABI 1,000 mg once daily with prednisone 5 mg daily, NIVO 480 mg IV every 4 weeks, and a CABO starting dose of 20 mg once daily at dose level 1 (DL1). If 0 of 3 pts at DL1 experience a DLT, 3 pts will be enrolled at DL2 with CABO 40 mg once daily. If 1 of 3 pts at DL1 experience a DLT, 3 additional pts will be enrolled at DL1. If 0 of 3 pts experience a DLT at DL2, the study will move to a recommended phase 2 dose (RP2D) expansion cohort. Total sample size of approximately 20 pts is expected depending on DLT frequencies. Enrollment is ongoing. Clinical trial information: NCT04477512.

A phase II trial of abemaciclib (abema) and atezolizumab (atezo) in unselected and CDK12-loss metastatic castration-resistant prostate cancer (mCRPC)

TPS213

Background: Alterations in the cell cycle signaling pathway are common in mCRPC and may contribute to resistance to AR-targeted therapies. Inhibitors of cyclin-dependent kinases 4 and 6 (CDK4/6i) have revolutionized the therapeutic landscape in ER+ breast cancer and have demonstrated robust anti-tumor activity in multiple pre-clinical mCRPC models such as enzalutamide-resistant cell lines, including those with the androgen-receptor splice variant 7 (AR-V7). Pre-clinical synergy has also been seen in multiple studies of CDK4/6i and anti-programmed death 1 (PD-1) or PD-ligand-1 (PD-L1). Additionally, loss of function alterations of CDK12, found in 5-7% of mCRPC, may confer vulnerability to anti-PD-L1 agents. Methods: This multi-center study will enroll 54 unselected mCRPC patients (pts), randomized 1:1 to abema (arm A) or abema + atezo (arm B); and 21 pts with known loss of function mutations in CDK12 (arm C) treated with atezo (n = 5) or abema + atezo (n = 16). All pts will undergo on-treatment (6-week) tumor biopsy. Treatment will be continued until disease progression and crossover is prohibited. Key eligibility criteria are age ≥ 18 years, ECOG PS 0-1, biopsy-proven prostate adenocarcinoma, progressive metastatic disease per Prostate Cancer Working Group 3 (PCWG3), progression/intolerance to ≥ 1 novel antiandrogen in hormone-sensitive or CRPC setting, ineligible for docetaxel/cabazitaxel (progression within 12 months of taxane, pt refusal, investigator discretion), no uncontrolled comorbidity or history of pneumonitis/ILD. Arms A & B will use two stage design for co-primary endpoints of progression-free survival at 6 months using PCWG3 (6m-PFS) and objective response rate (ORR). If ≥ 1/12 pts meet either co-primary endpoint, 2nd stage will open to enroll 15 more pts in that arm. Treatment will be deemed to have meaningful clinical activity (MCA) if ≥ 6/27 meet 6m-PFS or ≥ 5/27 have an ORR. This will provide 86% power for 6m-PFS (34% vs. 12%) and 85% power for ORR (30% vs. 10%) at a one-sided α = 0.08. For MCA in arm C, 16 patients treated with abema+atezo will provide 80-85% power for 6m-PFS (34% vs. 12%) at a one-sided α = 0.05 using a one-sample log-rank test. Primary safety endpoint is the incidence of dose-limiting toxicities in pts receiving abema+atezo. Key secondary endpoints are clinical benefit rate (ORR + stable disease), duration of response and overall survival in arms A and B, and safety events in all arms. Primary exploratory endpoint is comparison of tumoral FoxP3+/CD8+ ratio in pts treated with abema vs. abema + atezo. Additional exploratory endpoints will evaluate association between response and genomic alterations identified from tissue or circulating tumor-derived exosomes. Enrollment began in July 2021 and projected enrollment goal is 3 years (NCT04751929). Clinical trial information: NCT04751929.

Integrative analysis of urine cell-free DNA for the detection of residual disease in localized bladder cancer patients

559

Background: We previously developed a liquid biopsy assay to measure urine tumor DNA (utDNA) levels based on detection of single nucleotide variants (SNVs) in urine cell-free DNA (cfDNA). Nonsilent SNV detection in urine from muscle-invasive bladder cancer (MIBC) patients prior to radical cystectomy (RC) was associated with pathologic residual disease and worse progression-free survival (Chauhan et al., PLOS Medicine, 2021). Given the multiple types of genomic alterations present in bladder cancer (BC), here we developed a multi-omics approach for estimating utDNA levels without restricting our approach to SNVs. We performed ultra-low pass whole genome sequencing (ULP-WGS) based copy number analysis and urine Cancer Personalized Profiling by deep Sequencing (uCAPP-Seq) of urine cell-free DNA to predict pathologic complete response (pCR) in localized BC patients. Methods: We acquired urine preoperatively from 65 BC patients (69% muscle-invasive) on the day of standard-of-care RC, and after neoadjuvant chemotherapy in 48% of patients. We performed ULP-WGS of urine cfDNA from all 65 BC patients and 11 healthy adults. utDNA levels based on genome-wide copy number alterations (CNAs) in urine cfDNA was estimated using ichorCNA. In order to derive a SNV-based utDNA level as well, uCAPP-Seq was applied to urine cfDNA samples derived from 42 patients using a 145 kb panel of 49 consensus driver genes commonly mutated in MIBC. Results: In our cohort of 65 BC patients, 55% of patients achieved pCR ( n = 36) while 45% had residual disease detected in their surgical sample (no pCR; n = 29). Comparing ULP-WGS-derived utDNA levels between the groups, patients with no pCR had significantly higher CNA-derived tumor fractions in urine compared to patients with pCR (median 8.9% vs 1.8%, p = 0.01) and healthy adults ( n = 11) (median 8.9% vs 0%, p = 0.006). Further analysis with uCAPP-Seq in 42 patients revealed that nonsilent SNV-based utDNA detection correlated significantly with the absence of pCR ( p < 0.001) with a sensitivity of 81% and specificity of 81%. Moreover, utDNA-positive patients exhibited significantly worse progression-free survival compared to utDNA-negative patients (HR = 7.4; 95% CI: 1.4–38.9; p = 0.02). Conclusions: Bladder cancer patients who did not attain a pCR at the time of RC had greater genome-wide copy number alterations and nonsilent single nucleotide variants in their urine cfDNA compared to patients with pCR. These results suggest that integrative multi-omics of urine derived from MIBC patients has potential real-world clinical impact for bladder-sparing approaches in select patients.

Phase 1b study of tarlatamab, a half-life extended bispecific T-cell engager (HLE BiTEimmune therapy) targeting DLL3, in de novo or treatment emergent neuroendocrine prostate cancer (NEPC)

TPS197

Background: NEPC is an aggressive cancer with no standard treatment approach and poor prognosis. It is usually treatment-emergent, occurring in 15%–20% of patients (pts) with metastatic castration-resistant prostate cancer following treatment with androgen signaling inhibitors (ASI) and is characterized by histological transformation from adenocarcinoma to a high-grade neuroendocrine tumor.1 The tumor associated antigen delta-like ligand 3 (DLL3) has been identified as a promising target in both NEPC and small cell lung cancer (SCLC), as it is highly expressed in these tumors and minimally expressed on normal tissue. Tarlatamab is a DLL3-targeting HLE BiTE® immune therapy designed to bind DLL3 on cancer cells and CD3 on T cells, resulting in T cell activation and expansion and T cell-dependent killing of tumor cells. In preclinical studies, tarlatamab induced T-cell dependent lysis of DLL3-expressing neuroendocrine tumor cell lines, including NEPC cells.2 Interim results of an ongoing first-in-human study in pts with SCLC (NCT03319940) show evidence for tarlatamab efficacy with an acceptable safety profile.3 Together, these findings support a clinical study of tarlatamab in NEPC. Methods: NCT04702737 is an open-label, phase 1b study evaluating tarlatamab infusion in pts with metastatic de novo or treatment-emergent NEPC, consisting of dose exploration and then dose expansion. Key eligibility criteria include adults (≥18 y) with metastatic NEPC whose disease progressed/recurred after ≥1 prior line of systemic therapy (platinum-based regimen for de novo NEPC or an ASI if treatment-emergent), measurable disease per RECIST 1.1 with Prostate Cancer Working Group 3 modifications, and ECOG performance status ≤2. Primary objectives are to evaluate safety and tolerability and determine the maximum tolerated dose or recommended phase 2 dose of tarlatamab. Secondary objectives are to evaluate antitumor activity (as assessed by objective response, duration of response, progression-free survival, overall survival, and disease control rate) and characterize pharmacokinetics. Four US and international study sites have been activated with two enrolled pts. References: Aggarwal R, et al. J Clin Oncol. 2018;36:2492-2503. Cooke K, et al. Abstract 627. Presented at: SITC Annual Meeting, Nov 9–14, 2020; Virtual. Owonikoko TK, et al. Abstract 8510. Presented at: ASCO Annual Meeting, June 4–8, 2021; Virtual. Clinical trial information: NCT04702737.

Phase 2 trial of immunotherapy in tumors with CDK12 inactivation (IMPACT): Results from cohort A of patients (pts) with metastatic castration resistant prostate cancer (mCRPC) receiving dual immune checkpoint inhibition (ICI)

103

Background: Prostate cancer with CDK12 inactivation represents a distinct subtype in mCRPC, tumors are characterized by excessive tandem duplications, genomic instability, gene fusion-caused putative neoantigens and increased tumor T cell infiltration. Retrospective experiences with ICI in CDK12 inactivation CRPC pts reported PSA and radiographic responses. We conducted a prospective multi-site clinical trial of ipilimumab and nivolumab in CDK12 inactivation or mutated cancers. Herein, we report our findings in the completed cohort A of men with mCPRC. Methods: Eligible pts had mCRPC (ongoing androgen deprivation therapy with serum testosterone £ 50 ng/dL) and putative CDK12 inactivation of function aberrations on any commercial or institutional CLIA/CAP approved next generation sequencing assay. Archival tumor tissue was requested for correlative biomarker analysis. Pts received nivolumab 3 mg/kg IV and ipilimumab 1 mg/kg IV q3 weeks for up to 4 cycles, followed by maintenance nivolumab at 480 mg IV q4 weeks until disease progression, intolerable toxicity, or consent withdrawal. The primary endpoint was PSA response, defined as a greater than or equal to 50% decline in PSA from baseline. Secondary endpoints included safety/toxicity, secondary efficacy measures including QoL and overall survival. Exploratory objectives included baseline tumor whole exome analysis and changes in circulating immune profiles with therapy. Results: As of data cut-off in Aug 2021, 28 mCRPC pts enrolled in Cohort A; median ECOG PS was 1 (0-2 range), 22/28 had Gleason 8-10 cancer, mean baseline PSA at study entry was 231 ng/dL, all pts had received ≥1 prior oral androgen signaling inhibitor and ≥1 cytotoxic chemotherapy. Unconfirmed PSA ≥30% decline was seen in 6/28 pts (21.4%) and PSA ≥50% decline in 4/28 pts (14.2%). Grade ≥3 possible/probable/definite adverse events were noted in 7/28 (25%) and SAEs in 10/28 pts (35.7%). Six pts (21.4%) experienced a rapid PSA increase by ≥ 10-fold over baseline. Conclusions: Combination immunotherapy was reasonably tolerated in this heavily pre-treated population and was associated with unconfirmed PSA responses in a subset of pts. Ongoing correlative analyses could explain responses mechanistically. Enrollment in Cohort B of non-prostate cancers and Cohort C of nivolumab monotherapy in prostate cancer are still ongoing. Clinical trial information: NCT03570619.

PIVOT IO 011: A phase 1/2 study of bempegaldesleukin (BEMPEG; NKTR-214) plus nivolumab (NIVO) and tyrosine kinase inhibitor (TKI) versus NIVO and TKI alone in patients (pts) with previously untreated advanced or metastatic renal cell carcinoma (mRCC)

TPS403

Background: The current standard of care for advanced RCC (aRCC) utilizes immune checkpoint inhibitors (ICIs) and targeted agents. Novel combinations of these agents, such as NIVO + TKIs, have demonstrated clinical benefit over TKI monotherapy. In CheckMate 9ER, NIVO + cabozantinib (CABO) in aRCC demonstrated clinically meaningful efficacy results and a favorable safety profile, and was FDA approved (01/2021). High-dose interleukin-2 (IL-2) was used historically for durable responses in mRCC but had unfavorable toxicity with complex inpatient treatment regimens. BEMPEG, an immunostimulatory IL-2 cytokine prodrug, is engineered to deliver a controlled, sustained, and preferential signal to the clinically validated IL-2 pathway. Preferential binding of BEMPEG to the IL-2 heterodimeric receptor (IL-2Rβγ) activates and expands CD8+ T cells and NK cells over immunosuppressive Tregs. In the phase 1/2 PIVOT-02 study, BEMPEG + NIVO displayed encouraging antitumor activity in pts with mRCC, with a tolerable safety profile. The clinical activity and the manageable, non-overlapping toxicity profiles of the individual agents in this combination warrants exploration of triplet regimens in previously untreated aRCC. Methods: PIVOT IO 011 (NCT04540705) is a 2-part, phase 1/2, randomized, open-label study assessing the safety and efficacy of BEMPEG + NIVO + TKI triplet in pts with untreated aRCC or mRCC. In Part 1, pts will receive BEMPEG + NIVO + TKI (Part 1A: axitinib [AXI] or Part 1B: CABO; n≈6–24 pts in each TKI arm). While BEMPEG + NIVO dosing will remain consistent across phases, each TKI will have 2 doses evaluated in Part 1, and results will determine the recommended phase 2 dose for AXI/CABO in Part 2. In Part 2, pts will be randomized 1:1 to receive either BEMPEG + NIVO + CABO or NIVO + CABO (N≈250), stratified by IMDC prognostic score and prior nephrectomy status. If the CABO triplet has an unacceptable toxicity profile, Part 2 may be amended to use the AXI triplet. Key inclusion criteria: aRCC or mRCC with clear cell component; no prior systemic therapy for RCC, except 1 prior adjuvant/neoadjuvant therapy for completely resectable RCC (must have included an anti–VEGF agent with recurrence ≥6 months after last dose); and Karnofsky PS ≥70%. Key exclusion criteria: active CNS brain/leptomeningeal metastases; active, known, or suspected autoimmune disease; and inadequately treated adrenal insufficiency. Primary endpoints in Part 1: dose-limiting toxicities and safety; and in Part 2: overall response rate per RECIST v1.1 by investigator. Secondary endpoints in Part 2: progression-free survival, overall survival, safety. Duration of BEMPEG + NIVO will be ≤2 years, and treatment with TKI will continue until disease progression. The study is currently recruiting. Clinical trial information: NCT04540705.

The Courage study: A first-in-human phase 1 study of the CBP/p300 inhibitor FT-7051 in men with metastatic castration-resistant prostate cancer

TPS5085

Background: Prostate cancer is the second leading cause of cancer-related death among men in the U.S., largely due to metastatic disease that progresses despite hormonal therapy (tx). The role for androgen receptor (AR) signaling in prostate cancer and hormone tx resistance is well-established. CBP/p300 are essential co-activators of AR-mediated transcription. FT-7051 is an oral, potent, and selective inhibitor of CBP/p300 with activity in preclinical models of prostate cancer including models resistant to currently used AR inhibitors like enzalutamide. The Courage Study (NCT04575766) is a first-in-human, multicenter, phase 1, open-label study examining the safety, pharmacokinetics (PK), preliminary anti-tumor activity, and pharmacodynamics (PD) of FT-7051 for the treatment of men with metastatic castration-resistant prostate cancer (mCRPC) who have progressed despite prior tx and have been treated with at least one approved androgen receptor pathway inhibitor. The study will enroll up to 45 men with mCRPC at ̃8-15 US sites. Methods: The study employs a Bayesian optimal interval (BOIN) design with an accelerated titration. Patients (pts) will initially be enrolled in a dose level cohort size of 1 until a Grade 2 or higher toxicity occurs that is considered related to FT-7051 or the highest dose level is reached. Upon completion of the accelerated titration phase, subsequent cohorts will enroll 3-5 pts. Treatment: FT-7051 capsules will be administered on a 28 d cycle (21 d on / 7 d off) with Dose Levels -1 to 7 assigned per protocol using the BOIN design. Key inclusion criteria: Diagnosis of mCRPC with either adenocarcinoma or mixed histology AND rising PSA; previously failed at least one approved androgen receptor pathway inhibitor; ≥ 18 yrs of age; prior taxane chemotherapy permitted. Key exclusion criteria: Previous solid organ transplant, prior anticancer tx including prior tx with small molecules within 4 wks of first dose of study treatment, prior radiation tx within 4 wks prior to initiation of study treatment, prior androgen antagonist tx within 2 wks, prior radium-223 tx within 6 wks. Endpoints: Primary endpoints are to define the recommended phase 2 monotherapy dose of FT-7051 through assessments of DLTs, SAEs, clinically relevant AEs, and clinically relevant safety laboratory values. Key secondary endpoints include: PSA at 12 wks, time to PSA progression, time to radiographic progression, overall response rate, and plasma PK parameters. PD assessments of CBP/p300 inhibition in surrogate tissue, biomarker assessments in CTCs (AR, AR-v7), and peripheral blood are included. Duration: Pts will remain on study treatment until they are deemed to be no longer clinically benefiting (NLCB) by the treating Investigator or until unacceptable toxicity. Pt may be followed for survival for up to 24 months from last dose of study treatment. The first pt was dosed January 2021. Clinical trial information: NCT04575766.

Survival of veterans treated with enzalutamide and abiraterone in advanced prostate cancer

5032

Background: Abiraterone (AA) and enzalutamide (ENZ) are two second generation antiandrogens used to treat advanced prostate cancer, but no large head-to-head trials have been performed. These oral therapies are commonly used in older patients with medical comorbidities who are not candidates for chemotherapy or clinical trials and have different mechanisms of action, adverse events, and drug interactions. To understand survival of patients with prostate cancer, we studied United States veterans treated prior to approval of AA and ENZ for metastatic hormone sensitive prostate cancer when both drugs had approval for metastatic castration resistant prostate cancer. Methods: We identified patients treated with AA or ENZ between 9/10/2014 and 6/3/2017 in the Veterans Health Administration and followed them to April 2020. Age, Elixhauser comorbidity score, treatment with androgen deprivation therapy (ADT) and docetaxel were collected. Cox proportional hazards modeling was used to assess the association between first oral treatment (AA or ENZ) and overall survival, while adjusting for covariates. Results: Of 5895 patients, 2562 (43.5%) were initially treated with ENZ, 3333 (56.5%) with AA, and 3040 (51.6%) received only one of the two drugs during the study period. Patients initially treated with ENZ compared to AA were older (mean 75.9 vs. 75.0 years, p = 0.001), had higher mean comorbidity score (6.2 vs. 5.9, p < 0.001), and were less likely to receive both ENZ and AA (45.2% vs. 51.0%, p < 0.001) or docetaxel (24.1% vs. 28.4%, p < 0.001). Patients who received only AA or ENZ and never received docetaxel were older (mean 78.3 vs. 73.2 years, p < 0.001) with higher mean comorbidity scores (6.4 vs. 5.7, p < 0.001). In the entire cohort, initial treatment with ENZ was associated with longer median survival (24.1 vs. 22.2 months, p = 0.003). After adjusting for age and comorbidities, ENZ was associated with a decreased risk of death compared to AA (HR 0.87, 95% CI 0.82-0.92). In 3317 patients who received two or more therapies (ENZ, AA, docetaxel) there was no difference in median survival between initial treatment with ENZ or AA (28.0 vs. 27.9 months). In 2578 patients (43.7%) who never received docetaxel and either ENZ or AA only, median survival was longer in patients treated with ENZ (18.9 vs. 13.6 months, p < 0.001) and was associated with decreased mortality when adjusting for age and comorbidities (HR 0.73, 95% CI 0.67-0.80). Conclusions: In the overall cohort, initial treatment with ENZ was associated with increased survival compared to AA. Patients who received only ENZ or AA and never received docetaxel had the largest benefit from ENZ, a difference of 5.3 months median survival. Efforts should be made to improve therapy selection for patients with prostate cancer, especially older patients with comorbidities.

Tracking minimal residual disease with urine tumor DNA in muscle-invasive bladder cancer after neoadjuvant chemotherapy

e16514

Background: Standard-of-care for muscle-invasive bladder cancer (MIBC) consists of neoadjuvant chemotherapy (NAC) followed by radical cystectomy. The inability to noninvasively assess minimal residual disease (MRD) after NAC limits our ability to offer bladder-sparing treatment. We perform urine tumor DNA (utDNA) analysis to identify pathologic complete response (pCR) at the time of cystectomy in patients receiving NAC. Methods: We applied CAPP-Seq to urine cell-free DNA samples acquired on the day of radical cystectomy from 19 MIBC patients treated with NAC. utDNA variant-calling was performed without prior tumor mutational knowledge using a panel of 49 consensus driver genes mutated in MIBC. The utDNA level for each patient was represented by the duplex-supported non-silent driver mutation with the highest variant allele fraction (vAF) after removing germline variants. We also serially tracked utDNA variants in two patients before, during, and after NAC. Results: Comparing patients with residual disease detected in their cystectomy specimen ( n = 10) to those who achieved a pCR ( n = 9), median utDNA levels were 2.4% vs. 0%, respectively ( P = 0.006). Using an optimal utDNA threshold to define MRD detection, positive utDNA MRD was highly correlated with the absence of pCR ( P = 0.003). Analysis of two patients’ serial urine samples revealed utDNA dynamics that were consistent with treatment responses in real-time. In one patient who ultimately achieved a pCR, four non-silent driver mutations were detectable pre-NAC, including ERCC2 N238S (7.8% vAF) associated with increased chemosensitivity. One week after starting NAC, ERCC2 N238S increased by 1.6-fold in urine, as did PIK3CA E726K which increased by 8.4-fold. Four weeks post-NAC, however, all mutations previously detected in this patient’s urine became undetectable, consistent with the patient’s pCR and long-term disease-free survival. Conversely, another patient harbored two non-silent driver mutations in PLEKHS1 (1.9% vAF) and KMT2D (4.9% vAF) pre-NAC. One week after starting NAC, both mutations decreased dramatically by 8.0- and 4.3-fold, respectively. By three weeks post-NAC, however, these mutations progressively increased by 5.2-fold on average, which correlated with a lack of pCR as well as post-treatment disease progression. Two newly detected non-silent driver mutations in ARID1A and ERBB2 also emerged on NAC and persisted following completion of chemotherapy , likely reflecting the development of treatment resistance. Conclusions: utDNA MRD after NAC but before radical cystectomy for MIBC correlated significantly with pathologic response, which could help personalize patient selection for bladder-sparing treatments in the future. Serial monitoring of utDNA variants during NAC can reveal dynamic mutational changes that reflect real-time treatment responses as well as ultimate disease-free survival.

A pilot trial of neoantigen DNA vaccine in combination with nivolumab/ipilimumab and prostvac in metastatic hormone-sensitive prostate cancer (mHSPC)

TPS192

Background: Despite robust advances in the use of immune checkpoint blockade (ICB) across multiple cancer types, responses in prostate cancer remain suboptimal. Overall response rates for single-agent ICB in prostate cancer are low, but recent modest gains have been made with ipilimumab and nivolumab combination therapy in metastatic castrate-resistant prostate cancer. Prostvac-VF Tricom is a therapeutic vaccine that incorporates DNA for the shared self-antigen PSA into the vaccinia (or fowlpox) virus strain. A large randomized phase III clinical trial recently showed no improvement in overall survival (OS) with Prostvac compared with placebo, suggesting that a combinatorial approach is warranted. Personalized neoantigen vaccines based on specific mutated epitopes may have the ability to overcome immunoresistance seen with self antigens. Even in low mutational burden tumors like prostate cancer, T cell responses against neoantigens are observed in patients with favorable clinical outcomes, supporting neoantigen vaccination as a promising therapeutic strategy. Improvements in computational genomics and predictive algorithms have allowed the incorporation of MHC class II neoepitopes and those from gene fusion events relevant in prostate cancer. We thus hypothesized that a strategy utilizing both shared antigen (Prostvac) and personalized MHC-I and MHC-II neoantigen vaccines combined with dual ICB would induce robust immune responses and improve clinical outcomes. To maximize tumor burden reduction and minimize tumor-mediated immunoresistence, we are evaluating this novel strategy in patients with metastatic hormone-sensitive prostate cancer (mHSPC) who have completed frontline docetaxel chemotherapy. Methods: This ongoing trial (NCT03532217) began accrual in September 2018. Eighteen of 20 planned patients have been enrolled to date. Eligible patients have histologically confirmed high risk/volume mHSPC defined as 4 or more sites of metastatic disease or visceral involvement. Patients receive continuous androgen deprivation therapy (ADT) and have completed upfront docetaxel chemotherapy. Patients begin treatment with Prostvac-VF in combination with ipilimumab (1 mg/kg every 3 weeks for 2 doses), and nivolumab (3 mg/kg every 3 weeks for 6 doses) within 60 days of the last dose of docetaxel. Subsequently, patients receive nivolumab 480 mg IV every 4 weeks in conjunction with a personalized neoantigen DNA vaccine administered monthly via intramuscular electroporation. The primary objective of this exploratory study is to assess the feasibility, safety/tolerability, and immune responses of this combination strategy. Key secondary objectives include failure-free survival and milestone survival at 2 years, PSA response, and radiographic progression-free survival. Clinical trial information: NCT03532217.

Integrated clinicopathologic and molecular risk stratification for disease recurrence in muscle-invasive bladder cancer

490

Background: Integrating molecular subtypes, gene transcripts associated with disease recurrence (DR), and clinicopathologic features may help risk stratify muscle-invasive bladder cancer (MIBC) patients & guide therapy selection. We hypothesized that combined transcriptomic & clinical data would improve risk stratification for DR (local or distant) after cystectomy +/- adjuvant chemotherapy. Methods: We identified 401 MIBC patients (pT2-4 N0-N3 M0) in The Cancer Genome Atlas with detailed demographic, clinical, pathologic, and treatment-related data. We split the data into training (60%) & testing (40%) sets. We produced RNA gene expression scores for molecular subtype using 48 established, relevant genes (PMID 28988769). In the training set, we performed feature selection by conducting random forest modeling of an additional 108 genes associated with DR. We kept genes of highest importance based on the evaluation of increasing mean-squared error & node purity. We excluded highly correlated genes & used the false discovery rate method for multiple hypotheses testing. We performed univariable analyses on genes of highest importance, molecular subtype, & clinicopathologic variables. Using adjusted multivariable analyses (MVA), we built two models: with & without transcriptomic data. Using the testing set, we compared the final models' performance to predict DR, using receiver operating characteristics & area under the curve (AUC). Results: Median follow-up was 18 months (range 1-168). 104 patients recurred with a 5-yr cumulative incidence of 34.6%[28.6-40.5%]. Using the training set, we identified 6 genes significantly associated with DR (VEGFA, TRMT1, FGFR2B, ERBB2, MMP14, PDGFC). The final MVA showed that the new 6-gene signature (HR 1.61, 95% CI 1.27-2.05, p < 0.001); immune molecular subtype [increased expression of PD-L1, PD-1, IDO1, CXCL11, L1CAM, SAA1] (HR 0.52, 95% CI 0.29-0.94, p = 0.03); smoking status (HR 1.17 per 10 pack-years, 95% CI 1.05-1.29, p = 0.005); and local failure risk factors [≥pT3 with negative margins & ≥10 nodes removed (HR 1.63, 95% CI 1.15-2.32, p = 0.006); ≥pT3 and positive margins OR < 10 nodes removed (HR 3.26, 95%CI 2.43 to 4.09, p = 0.007)], were all significantly associated with DR. This combined model outperformed a stand-alone clinicopathologic model (AUC 0.75 vs. 0.66) in the testing set. The combined model stratified patients based on DR risk into 3 groups with 5-yr cumulative incidences of 19.8%[7.7-31.9%] (low-risk); 34.5%[26.1-42.8%] (intermediate); and 49.8%[37.7-61.9%] (high), Gray’s Test p < 0.0001. Conclusions: To our knowledge, this study is the first to integrate clinicopathologic & transcriptomic information (including molecular subtype) to better stratify MIBC patients by risk of recurrence. This stratification may help guide decision-making for adjuvant treatment. Further validation is warranted.

IMPACT: Immunotherapy in patients with metastatic cancers and CDK12 mutations

TPS5091

Background: Tumors with biallelic CDK12 loss have been identified as a distinct subtype in metastatic castration resistant prostate cancer (mCRPC) and other cancer types. The CDK12 biallelic loss mCRPC genomic signature, distinct from homologous recombination deficient (HRD) and ETS fusion signatures, is characterized by excessive tandem duplications, genomic instability, gene fusion-caused putative neoantigens, and increased tumor T cell infiltration. Early clinical experience with anti-PD-1 immunotherapy in CDK12 loss mCRPC patients (pts) is notable for deep and sustained PSA as well as radiographic responses. We hypothesize that CDK12 biallelic loss is a potential biomarker of immune checkpoint immunotherapy (ICI) efficacy in mCRPC and other cancers. Methods: IMPACT (NCT03570619) is a multi-center, open label, phase 2 study of pts with metastatic cancers that harbor CDK12 biallelic loss. mCRPC pts will be enrolled in cohort A (n = 25) in a Mini-Max Simon Two-Stage design, and all other pts in single-stage cohort B (n = 15). All pts will receive induction therapy with nivolumab 3 mg/kg IV and ipilimumab 1 mg/kg IV q3 weeks for up to 4 cycles, followed by maintenance nivolumab at 480 mg IV q4 weeks (up to 52 weeks in total). Eligible pts must have identified biallelic CDK12 loss on any CLIA/CAP approved next generation sequencing assay and a histologic diagnosis of metastatic prostate adenocarcinoma or other metastatic carcinoma. No prior ICI is allowed. The primary endpoint is the overall response rate (ORR) in cohort A per PCWG3 criteria. An ORR of 30% is targeted in cohort A. Secondary endpoints include safety, secondary efficacy measures, quality of life, and survival measures. Exploratory objectives include tumor whole exome analysis and changes in immune profiles with therapy. Comprehensive and serial monitoring of peripheral blood immune cell populations will be performed via T cell clonal diversity assessment and multi-parametric flow cytometry. Changes in myeloid and lymphoid populations will be assessed from whole blood. Polarization and effector function of T cells and activation of antigen presenting cells will be further characterized from isolated peripheral blood mononuclear cells. Study accrual is ongoing. Clinical trial information: NCT03570619.

Enterobacteria associated with houseflies (Musca domestica) as an infection risk indicator in swine production farms

Houseflies (Musca domestica) spend part of their life development on animal or human manure. Manure is high in pathogenic microbes; thus, houseflies have been known as a mechanical vector for various important zoonotic diseases. Therefore, the present study showcases captured houseflies from intensive swine production regions (which are areas of high manure concentration) in Southern Brazil, and analyses their bodies' to the presence of Escherichia coli and Salmonella sp. and the sensitivity of these bacteria to various antibiotics. Additionally, Quantitative Microbiology Risk Assessment was performed simulating the contamination of lettuce by flies' bacteria and subsequent lettuce consumption by an adult human being. Houseflies were captured in swine buildings and farm houses from five farms. E. coli quantification values ranged from 10⁴ to 10⁶ CFU/20 flies, and all sampling sites had positive results from bacteria presence in the collected houseflies. On the other hand, Salmonella sp. presence was observed in only three farms, where the quantification ranged from 10² to 10⁵ CFU/20 flies. The bacteria showed to be resistant to at least two from the four tested antibiotics (ampicillin, Cefalotin, Ciprofloxacin and Norfloxacin) antibiotics used in human or veterinary medicine. Infection probability analyses showed risk of human infection by E.coli, indicating possible transmission of zoonotic pathogens through flies. In this context, it was possible to conclude that there is a need for flies control, especially in swine farms where zoonotic pathogens can be abundant, to minimize the health impact of the vectorization of enteric bacteria.

Radium-223 and atezolizumab in platinum refractory urothelial carcinoma with bone metastases: NCT03208712

TPS543

Background: Immunologically, radiation increases tumor antigen release, cytotoxic CD8+ T cell infiltration while reducing myeloid derived suppressor cells (MDSCs), with distant abscopal responses occasionally reported. Radium-223 is a systemically administered bone-targeted alpha emitter that causes double-stranded DNA breaks and may induce similar immune effects. Anti-PD(L1) immune checkpoint inhibitor monotherapy with Atezolizumab demonstrates objective responses in metastatic urothelial cancer. In mouse models, radiotherapy and checkpoint immune inhibitor in combination synergistically reduce tumor growth. We hypothesized that the combination of Atezolizumab and Radium-223 in metastatic urothelial cancer pts with bone metastases would target bone metastases more effectively and yield higher response rates. Methods: Eligibility criteria for this single-site, phase 2 trial of Radium-223 in combination with Atezolizumab include diagnosis of advanced urothelial carcinoma with ≥1 bone metastasis, RECIST 1.1 measurable disease, progression of disease after/on platinum-containing chemotherapy in the metastatic or perioperative setting, ECOG PS of 0-2 and adequate organ function. Twenty-two pts will be treated with Radium-223 at a dose of 55 kBq/kg IV and Atezolizumab 1200mg IV both on day 1 of 21 day cycles. Up to 6 doses of Radium-223 will be administered. Atezolizumab will be continued until lack of clinical benefit or intolerable toxicity for up to 17 cycles. Routine response assessment will be performed every 12 weeks. Primary endpoint is best overall response per RECIST 1.1. Secondary objectives are to determine the safety and tolerability; determine the overall survival, progression free survival, clinical benefit rate, complete response rate and duration of response; and changes in quality of life as assessed by the EORTC QLQ-C30 score. Exploratory objectives are PD-L1 status by IHC, changes in bone scan per EXINI bone scan index and efficacy measures by irRC. If ≥6 pts respond, corresponding to an ORR of 27% with 80% confidence limits of 15%-43%, further study of the combination would be warranted. Blood and archival tissue will be collected for correlative studies. Clinical trial information: NCT03208712.

Pazopanib with low fat meal (PALM) in advanced renal cell carcinoma (RCC)

683

Background: Pazopanib, a highly lipophilic standard first-line therapy for metastatic RCC, is conventionally taken in a fasting state but has significant gastrointestinal toxicities and 96% of ingested drug is fecally excreted, with major financial implications. Single dose studies with fat meals suggested bioavailability is increased two-fold. We sought to evaluate toxicity/safety, bioavailability and anti-tumor efficacy of daily pazopanib taken with a low fat meal over 12 weeks. Methods: Enrolled pts had unresectable locally advanced or metastatic RCC with clear cell component, RECIST 1.1 measurable disease, ECOG PS ≤2, adequate organ function, and up to 3 prior therapies including VEGF(R) and checkpoint inhibitors. Subjects took pazopanib, starting dose of 400 mg, once daily with low-fat meal ( < 400 cal with < 20% fat/10 g of fat) in 2 wk cycles with MD discretion to dose-escalate q2wks up to 800 mg or irreversibly dose-reduce as low as 200 mg based on tolerance/toxicity for 12 wks. Baseline and end of study echocardiograms, and triplicate ECGs at each cycle start were monitored. Home pill diaries were collected. PK was analyzed in the first 3 cycles. Results: Sixteen pts were accrued: median age 60 (range: 47 – 75),75% men,11 were ECOG PS 0. Most (12/16) subjects with no prior therapy, 13/16 had intermittent Heng risk criteria, 3 favorable; 5 sarcomatoid component. Diet compliance by pill diary was outstanding, except for 1 pt for 1 cycle. Calculated mean daily dose was 535 mg (153-750 mg). Therapy was well tolerated; 5 Grade 3 AEs (1 HTN, 1 chest pain, 2 AST/ALT elevations, 1 Abd pain) occurred. LVEF declined by > 15% in 3 pts but none to < 50%. QTc prolongation > 450 ms did not occur. All but 3 pts completed protocol (off d/t toxicity-HTN, LFTs, chest pain). ORR was PR 5 (31%); SD 7 (44%). PK data and pharmacogenomics CYP3A4 polymorphism data correlated with toxicity. Conclusions: Pazopanib taken with a low fat meal appears to be better tolerated compared to published data on empty stomach administration, especially with fewer GI toxicities, including diarrhea. It also resulted in comparable efficacy with fewer cumulative pills over the 12-week period, with substantial cost implications. Larger trials of pazopanib with low fat meal are warranted. Clinical trial information: NCT02729194.

Single-arm phase ib/II study of durvalumab and guadecitabine in advanced kidney cancer (NCT03308396)

TPS711

Background: Checkpoint inhibitor immunotherapy directed at PD1/PDL1 has shown clinical efficacy in advanced clear cell Renal Cell Cancer (ccRCC). However, only a minority of patients respond to anti-PD1 monotherapy. There is an urgent unmet need to improve response rates including through rational combinations to reverse immune evasion by tumors. The chemokines CXCL9 and CXCL10 in the tumor micro-environment are chemo-attractants for activated NK and Th1 cells and are critical for anti-tumor immunity. Preclinical data from our group showed hypermethylation induced silencing of CXCL9/10 signaling is an important tumor immune evasion mechanism. In RCC cell lines (A-498, HTB-46 and CRL-1611), hypomethylating agents increased CXCL9/10. In mouse xenograft models, combination therapy with a hypomethylating agent and checkpoint inhibitors led to higher levels of CXCL 9/10, reversal of immune evasion and potent tumor regression. We hypothesized that the combination of guadecitabine (hypomethylating agent) with durvalumab (anti-PDL1 antibody) would increase T lymphocyte infiltration into RCC tumors including those that are immunologically ‘cold’ and result be effective in 1st and 2nd line RCC. Methods: The study is a single arm, multi-site, phase 1b/2 trial through the Big Ten Cancer Research Consortium of Guadecitabine (starting dose of 60 mg/m2/dose subcutaneously on days 1-5) with Durvalumab (1500 mg IV on day 8) in 28-day cycles in pts with metastatic ccRCC. Cohort 1 (N = 36) will consist of pts naïve to checkpoint inhibitor immunotherapy and 0-1 prior therapies. Cohort 2 (N = 16) will include pts who did not respond to prior anti-PD-1/PD-L1 therapy. The primary endpoint is objective response rate by RECIST 1.1 in cohort 1. Statistical analysis will use a binomial exact test to compare the ORR proportion in patients treated in Cohort 1 with the combination compared to an expected proportion of 25% with anti-PDL1 alone. The extensive correlative objectives include serial evaluation of serum CXCL9/10 levels and LINE-1 methylation status as well as tumor infiltrating lymphocytes profiling, PD-L1 expression, tumor mutational burden and NGS on mandatory baseline and optional biopsies at progression. Clinical trial information: NCT03308396.

Interactive molecular networks obtained by computer-aided conversion of microarray data from brains of alcohol-drinking rats

Lists of differentially expressed genes in a disease have become increasingly more comprehensive with improvements on all technical levels. Despite statistical cutoffs of 99% or 95% confidence intervals, the number of genes can rise to several hundreds or even thousands, which is barely amenable to a researcher's understanding. This report describes some ways of processing those data by mathematical algorithms. Gene lists obtained from 53 microarrays (two brain regions (amygdala and caudate putamen), three rat strains drinking alcohol or being abstinent) have been used. They resulted from analyses on Affymetrix chips and encompassed approximately 6 000 genes that passed our quality filters. They have been subjected to four mathematical ways of processing: (a) basic statistics, (b) principal component analysis, (c) hierarchical clustering, and (d) introduction into Bayesian networks. It turns out, by using the p-values or the log-ratios, that they best subdivide into brain areas, followed by a fairly good discrimination into the rat strains and the least good discrimination into alcohol-drinking vs. abstinent. Nevertheless, despite the fact that the relation to alcohol-drinking was the weakest signal, attempts have been made to integrate the genes related to alcohol-drinking into Bayesian networks to learn more about their inter-relationships. The study shows, that the tools employed here are extremely useful for (a) quality control of datasets, (b) for constructing interactive (molecular) networks, but (c) have limitations in integration of larger numbers into the networks. The study also shows that it is often pivotal to balance out the number of experimental conditions with the number of animals.