Combined Androgen Deprivation Research Articles

Hypofractionated radiation therapy combined with androgen deprivation therapy for clinically node-positive prostate cancer.

This study aimed to analyze the treatment outcomes of combined definitive radiation therapy (RT) and androgen deprivation therapy (ADT) for clinically node-positive prostate cancer. Medical records of 60 patients with clinically suspected metastatic lymph nodes on radiological examination were retrospectively analyzed. Eight patients (13.3%) were suspected to have metastatic common iliac or para-aortic lymph nodes. All patients underwent definitive RT with a dose fractionation of 70 Gy in 28 fractions. ADT was initiated 2-3 months before RT and continued for at least 2 years. Biochemical failure rate (BFR), clinical failure rate (CFR), overall survival (OS), and prostate cancer-specific survival (PCSS) were calculated, and genitourinary and gastrointestinal adverse events were recorded. The median follow-up period was 5.47 years. The 5-year BFR, CFR, OS, and PCSS rates were 19.1%, 11.3%, 89.0%, and 98.2%, respectively. The median duration of ADT was 2.30 years. BFR and CFR increased after 3 years, and 11 out of 14 biochemical failures occurred after the cessation of ADT. Grade 2 and beyond late genitourinary and gastrointestinal toxicity rates were 5.0% and 13.3%, respectively. However, only two grade 3 adverse events were reported, and no grade 4-5 adverse events were reported. Patients with non-regional lymph node metastases did not have worse BFR, CFR, or adverse event rates. This study reported the efficacy and tolerable toxicity of hypofractionated definitive RT combined with ADT for clinically node-positive prostate cancer. Additionally, selected patients with adjacent non-regional lymph node metastases might be able to undergo definitive RT combined with ADT.

Hormonal Therapy and Radiation Therapy in Prostate Cancer: 5-Year Outcomes From a Trial Evaluating Combined Androgen Blockade With 5-Alpha Reductase Inhibitors as an Alternative to Gonadotropin Releasing Hormone Agonists

BackgroundWe previously reported that for men undergoing combined androgen deprivation therapy (ADT) and radiation therapy (RT) for prostate cancer, substitution of LHRH-agonists with 5-α- reductase inhibitors (5-ARIs) led to improved preservation of 6-month hormonal quality of life (hQOL). With longer term follow-up, we evaluated disease control. MethodsIn this non-randomized trial, men with unfavorable intermediate or high-risk prostate cancer, aged ≥70 years or with Charlson Comorbidity Index ≥2, were treated with RT (78-79.2 Gy in 39-44 fractions) and either oral ADT (oADT; 5-ARI with antiandrogen) or standard of care ADT (SOC; leuprolide with antiandrogen) for up to 28 months. The primary endpoint was EPIC hQOL; secondary endpoints included biochemical control and survival as well as changes in cholesterol and hemoglobin levels. ResultsBetween 2011 and 2018, 70 men were enrolled (40 in oADT; 30 in SOC). Median follow-up was 65 months [IQR 36-94]. Five-year freedom from biochemical failure for oADT and SOC was 89% versus 86%, disease free survival was 62% versus 69%, cancer-specific survival was 100% versus 96%, and overall survival was 70% versus 81% (all P>.1). Testosterone (2 mo through 3 yr) and hemoglobin levels (2 mo through 2 yr) were higher, and cholesterol levels (1 yr) were lower in the oADT groups (all P < .05). ConclusionsIn this non-randomized study, men treated with combined RT and oADT had better preservation of hQOL and comparable 5-year disease outcomes to men treated with SOC. Eugonadal testosterone with this approach may yield measurable benefits in cholesterol and hemoglobin levels.

Efficacy and Safety of Radiotherapy Plus Relugolix in Men With Localized or Advanced Prostate Cancer

Combination androgen deprivation therapy (ADT) with radiotherapy is commonly used for patients with localized and advanced prostate cancer. To assess the efficacy and safety of the oral gonadotropin-releasing hormone antagonist relugolix with radiotherapy for treating prostate cancer. This multicenter post hoc analysis of patients with localized and advanced prostate cancer receiving radiotherapy in 2 randomized clinical trials (a phase 2 trial of relugolix vs degarelix, and a subset of the phase 3 HERO trial of relugolix vs leuprolide acetate) included men who were receiving radiotherapy and short-term (24 weeks) ADT (n = 103) from 2014 to 2015 and men receiving radiotherapy and longer-term (48 weeks) ADT (n = 157) from 2017 to 2019. The data were analyzed in November 2022. Patients receiving short-term ADT received relugolix, 120 mg, orally once daily (320-mg loading dose) or degarelix, 80 mg, 4-week depot (240-mg loading dose) for 24 weeks with 12 weeks of follow-up. Patients receiving longer-term ADT received relugolix, 120 mg, orally once daily (360-mg loading dose) or leuprolide acetate injections every 12 weeks for 48 weeks, with up to 90 days of follow-up. Castration rate (testosterone level <50 ng/dL [to convert to nmol/L, multiply by 0.0347) at all scheduled visits between weeks 5 and 25 for patients receiving short-term ADT and weeks 5 and 49 for patients receiving longer-term ADT. Of 260 patients (38 Asian [14.6%], 23 Black or African American [8.8%], 21 Hispanic [8.1%], and 188 White [72.3%] individuals), 164 (63.1%) received relugolix. Relugolix achieved castration rates of 95% (95% CI, 87.1%-99.0%) and 97% (95% CI, 90.6%-99.0%) among patients receiving short-term and longer-term ADT, respectively. Twelve weeks post-short-term relugolix, 34 (52%) achieved testosterone levels to baseline or more than 280 ng/dL. Ninety days post longer-term ADT, mean (SD) testosterone levels were 310.5 (122.4) (106.7) ng/dL (relugolix; n = 15) vs 53.0 ng/dL (leuprolide acetate; n = 8) among the subset assessed for testosterone recovery. Castration resistance-free survival was not statistically different between the relugolix and leuprolide acetate cohorts (hazard ratio, 0.97; 95% CI, 0.35-2.72; P = .62). Adverse events grade 3 or greater for short-term or longer-term relugolix (headache, hypertension, and atrial fibrillation) were uncommon (less than 5%). The results of these 2 randomized clinical trials suggest that relugolix rapidly achieves sustained castration in patients with localized and advanced prostate cancer receiving radiotherapy. No new safety concerns were identified when relugolix was used with radiotherapy.

Palliative surgery for metastatic prostate cancer

Androgen deprivation in combination with novel hormonal agents, docetaxel, or in combination with abiraterone/prednisone plus docetaxel or darolutamid plus docetaxel represent the standard therapeutic approach in metastatic hormone-sensitive prostate cancer (mHSPC). Patients with low-risk prostate cancer also benefit from additional radiation therapy or radical prostatectomy in terms of progression-free and overall survival. Despite favorable response rates, basically all patients will develop castration resistant prostate cancer (CRPC) within 2.5to 4years. In addition to systemic chemotherapy, second-line hormonal treatment of systemic application of radionuclides such as radium223 or 177Lu-PSMA represent salvage management options. However, nowadays about 50-65% of patients will develop symptoms due to local progression of prostate cancer which is the result of improved oncological outcomes with significantly prolonged survival times due to the new medical treatment options. Management of such symptomatic local progression will become more important in upcoming years so that all uro-oncologists need to be aware of the various surgical management options. Complications of the lower urogenital tract such as recurrent gross hematuria ± bladder clotting and with the necessity for red blood cell transfusions, subvesical obstruction and acute urinary retention, rectourethral or rectovesical fistulas might be managed by palliative surgery such as palliative transurethral resection of the prostate (TURP), radical cystectomy, radical cystoprostatectomy with urinary diversion, and pelvic exenteration. Symptomatic or asymptomatic obstruction of the upper urinary tract might be managed by endoluminal or percutaneous urinary diversion, ureteral reimplantation, ileal ureter replacement, or implantation of the Detour® system (Coloplast GmbH, Hamburg, Germany).

Metastasis-directed therapy in prostate cancer

Metastasis-directed therapy (MDT) in oligometastatic prostate cancer (omHSPC) is playing an increasingly important role in therapy with the aim of delaying disease progression, the start of systemic treatment or switching systemic treatment to improve the patient's overall prognosis. Molecular imaging as prostate-specific membrane antigen positron emission tomography (PSMA-PET) imaging allows metastases to be detected with ahigher sensitivity and specificity. This means that they can be detected early and made accessible for treatment. The standard therapy for oligo-mHSPC is androgen deprivation (ADT), which is supplemented by novel hormonal therapeutics (NHT). Afew small prospective trials have shown an extension of the ADT-free interval and progression-free survival (PFS), particularly in metachronous oligo-mHSPC, by MDT, usually radiotherapy. Additional ADT can further extend the PFS in particular. There are hardly any prospective data for synchronous oligo-mHSPC. Despite the currently still poor evidence, MDT is playing an increasingly important role. The still unclear definition of oligometastasis and the large number of influencing factors make it difficult to compare current data. Large multicenter prospective data are still pending. It is also important to clarify the effect of limited ADT in combination with NHT in the treatment of synchronous and metachronous oligo-mHSPC with MDT. In synchronous oligo-mHSPC in particular, further benefit of additional local therapy of the primary in combination with MDT should also be investigated.

Updated 5-year results for short course abiraterone acetate and LHRH agonist for unfavorable intermediate and favorable high-risk prostate cancer.

Combined androgen deprivation therapy (ADT) and radiotherapy (RT) improves outcomes for intermediate and high-risk prostate cancer. Treatment intensification with abiraterone acetate/prednisone (AAP) provides additional benefit for high-risk disease. We previously reported 3-year outcomes of a single-arm prospective multicenter trial (AbiRT trial) of 33 patients with unfavorable intermediate risk (UIR) and favorable high risk (FHR) prostate cancer undergoing short course, combination therapy with ADT, AAP, and RT. Here we report the final analysis demonstrating a high rate of testosterone recovery (97%) and excellent biochemical progression-free survival (97%) at 5 years. These data support comparative prospective studies of shorter, more potent ADT courses in favorable high-risk prostate cancer.

Palliative urologic surgery for metastatic prostate cancer: what needs to be considered in the future?

Androgen deprivation in combination with novel hormonal agents, docetaxel or the combination of abiraterone/prednisone plus docetaxel or darolutamide plus docetaxel represent the standard therapeutic approach in metastatic hormone-sensitive prostate cancer (mHSPC). Patients with low-risk prostate cancer also benefit from additional radiation therapy or radical prostatectomy in terms of progression-free and overall survival. Despite favourable response rates, basically all patients will develop castration-resistant prostate cancer (CRPC) within 2.5 to 4 years. Systemic chemotherapy, second-line hormonal treatment or systemic application of radionuclides such as Radium-223 or 177Lu-PSMA represent salvage management options. As the new medical treatment options have led to an improved oncological outcome with significantly prolonged survival times, about 50% to 65% of patients will develop symptoms due to local progression of prostate cancer. The management of such symptomatic local progression will become more important in upcoming years, which means that all uro-oncologists need to be aware of the various surgical management options. If complications of the lower urogenital tract occur, for example repetitive gross haematuria with or without bladder clotting and with the necessity for red blood cell transfusions, subvesical obstruction, acute urinary retention or rectourethral or rectovesical fistulas, these may be managed by palliative surgery such as palliative TURP, radical cystectomy, radical cystoprostatectomy with urinary diversion, and pelvic exenteration. Symptomatic or asymptomatic obstruction of the upper urinary tract can be managed by endoluminal or percutaneous urinary diversion, ureteral reimplantation, ileal ureter replacement, or implantation of a Detour system. However, an individualised and risk-adapted treatment strategy needs to be developed for each single patient to achieve an optimal therapeutic outcome with improvement of both symptoms and quality of life. In specific clinical situations, best supportive care may be an adequate option.

SAT634 The Androgen Receptor Does Not Directly Regulate The Transcription Of DNA Damage Response Genes

Abstract Disclosure: S. Hasterok: None. T.G. Scott: None. D.G. Roller: None. A. Spencer: None. A.B. Dutta: None. K. Sathyan: None. D.E. Frigo: None. M.J. Guertin: None. D. Gioeli: None. The clinical success of combined androgen deprivation therapy (ADT) and radiation therapy (RT) in prostate cancer (PCa) created interest in understanding the mechanistic links between androgen receptor (AR) signaling and the DNA damage response (DDR). Convergent data have led to a model where AR both regulates, and is regulated by, the DDR. Integral to this model is that the AR regulates the transcription of DDR genes both at steady state and in response to ionizing radiation (IR). In this study, we sought to determine which immediate transcriptional changes are induced by IR in an AR-dependent manner. Using PRO-seq to quantify changes in nascent RNA transcription in response to IR, the AR antagonist enzalutamide, or the combination of the two, we find that enzalutamide treatment significantly decreased expression of canonical AR target genes but had no effect on DDR gene sets in PCa cells. Surprisingly, we also found that the AR is not a primary regulator of DDR genes either in response to IR or at steady state in asynchronously growing PCa cells. Our data indicate that the clinical benefit of ADT and RT is not due to the direct regulation of DDR gene transcription by AR and that the clinical benefit of this therapeutic combination is instead likely due to both treatments independently reducing tumor cell fitness. Presentation: Saturday, June 17, 2023

Double trouble for prostate cancer: synergistic action of AR blockade and PARPi in non-HRR mutated patients.

Prostate cancer (PCa) is the most common cancer in men worldwide. Despite better and more intensive treatment options in earlier disease stages, a large subset of patients still progress to metastatic castration-resistant PCa (mCRPC). Recently, poly-(ADP-ribose)-polymerase (PARP)-inhibitors have been introduced in this setting. The TALAPRO-2 and PROpel trials both showed a marked benefit of PARPi in combination with an androgen receptor signaling inhibitor (ARSI), compared with an ARSI alone in both the homologous recombination repair (HRR)-mutated, as well as in the HRR-non-mutated subgroup. In this review, we present a comprehensive overview of how maximal AR-blockade via an ARSI in combination with a PARPi has a synergistic effect at the molecular level, leading to synthetic lethality in both HRR-mutated and HRR-non-mutated PCa patients. PARP2 is known to be a cofactor of the AR complex, needed for decompacting the chromatin and start of transcription of AR target genes (including HRR genes). The inhibition of PARP thus reinforces the effect of an ARSI. The deep androgen deprivation caused by combining androgen deprivation therapy (ADT) with an ARSI, induces an HRR-like deficient state, often referred to as "BRCA-ness". Further, PARPi will prevent the repair of single-strand DNA breaks, leading to the accumulation of DNA double-strand breaks (DSBs). Due to the induced HRR-deficient state, DSBs cannot be repaired, leading to apoptosis.

The oncologic and safety outcomes of low-dose-rate brachytherapy for the treatment of prostate cancer.

Around 40years have passed since a modern low-dose-rate (LDR) brachytherapy for prostate cancer was introduced. LDR brachytherapy has become one of the definitive treatment options besides radical prostatectomy (RP) and external beam radiation therapy (EBRT). LDR brachytherapy has several advantages over EBRT such as a higher prescribed dose to the prostate gland while avoiding unnecessary irradiation of organs at risk, a precipitous dose gradient, a brief treatment time, and a short hospital stay. Previous reports revealed that the long-term oncologic outcomes of LDR brachytherapy are superior to those of EBRT. The oncologic outcomes of low- to intermediate-risk patients are equivalent to those of RP using the recurrence definition of surgery of prostate specific antigen (PSA) >0.2ng/mL, while the oncologic outcomes of LDR brachytherapy as tri-modality (combined EBRT and androgen deprivation therapy) for high-risk patients is superior to that of RP using the recurrence definition of surgery. In respect of toxicity, urinary disorders such as urgency and frequency are often observed after the acute phase of treatment, but these events usually resolve, while the quality of life of urinary continence is well preserved for a long time. Erectile function decreases yearly, but is relatively preserved compared to RP. In conclusion, the most noteworthy strength of LDR brachytherapy for low- to intermediate-risk patients is the "brief treatment time" that provides long recurrence-free survival, while that for high-risk patients who received LDR brachytherapy (tri-modality) is "excellent disease control."

Relationship between androgen biosynthesis linked to 3βHSD1 and resistance to radiotherapy: A germline biomarker for combined androgen blockade with radiation in high-risk prostate cancer.

e17084 Background: Around 50% of men with advanced prostate cancer (PCa) have at least one germline copy of the adrenal-permissive (1245C) HSD3B1 allele. This allele leads to higher levels of the steroid biosynthesis enzyme, 3β-hydroxysteroid dehydrogenase (3βHSD1). Inheriting this allele is linked to worse outcomes in men with advanced PCa. To determine if (1245C) HSD3B1 could be causing early resistance to combined androgen deprivation and radiotherapy in localized PCa, we studied its role in modulating radioresistance. Methods: PCa cell lines were used to investigate the reciprocal effects of 3βHSD1 knockdown and overexpression in intrinsically high and low 3βHSD1 lines, respectively. PCa xenografts were used to confirm the results in vivo. The connection between androgen receptor (AR) expression and elevated DNA Damage Response (DDR) gene expression was validated using transcriptomic data from 680 radical prostatectomy specimens The ability of enzalutamide, a non-steroidal anti-androgen, to restore radiosensitivity in 1245C expressing lines was interrogated in vitro and in vivo. Results: 1245C HSD3B1 expressing PCa lines displayed increased clonogenic survival after ionizing radiation. Effects were dependent on the 3βHSD1 substrate, DHEA, confirming intratumoral androgen metabolism was required for radioresistance. Resistant lines showed enhanced DNA double-strand break (DSB) repair and heightened DDR gene expression. PCa xenografts with 1245C HSD3B1 were similarly more resistant to radiation using murine models that faithfully mimic human adrenal physiology. A correlation between AR expression and increased DDR gene expression was confirmed in 680 patient samples. Enzalutamide pretreatment resulted in a decrease in DSB repair ability and re-sensitized 1245C HSD3B1 PCa cells to radiation. Conclusions: 1245C HSD3B1 fuels prostate cancer treatment resistance by elevating regional androgen biosynthesis from adrenal steroid precursors, leading to DDR gene overexpression and enhanced DNA DSB repair kinetics. This work supports clinical validation of biomarker informed selective intensification strategies, e.g., combined androgen blockade, for high-risk men with the 1245C HSD3B1 allele receiving curative intent radiotherapy.

Novel mechanisms of androgen receptor-centered transcriptional regulatory network in regulating CD8 +T cell exhaustion and sex bias in cancer

Abstract Sex bias in cancers arising from nonreproductive organs is known but poorly understood. We recently reported on a T cell-intrinsic role of androgen receptor (AR) in driving CD8 +T cell exhaustion which underlies the poorer tumor control in males (Kwon et al., Sci Immunol, 2022). This study aims to understand how AR regulates CD8 +tumor-infiltrating lymphocytes (TILs) by identifying its genome-wide targets. We created a CD8 +T cell-specific AR knockout (KO) mouse model by crossing E8I-cre mice with Ar-floxed mice, which we challenged with syngeneic bladder tumor MB49. We then monitored tumor growth and performed spectral flow cytometry using a T cell exhaustion panel. Further, we used Cleavage Under Targets and Tagmentation – sequencing (CUT&amp;Tag-seq) to map the entire AR targets in CD8 +TILs. Loss of AR in CD8 +T cells significantly slowed the growth of MB49 in male but not female mice. CD8 +TILs from male CD8 AR KO mice showed reduced TOX +TCF1 −terminally exhausted subset (69%; P≤ 0.05) and TOX expression (72%; P = 0.0583) compared to controls. Similarly, TOX expression decreased by 43% in AR-deleted CD8 +T cells following chronic TCR stimulation in vitro (P ≤ 0.0001). Finally, using CUT&amp;Tag-seq, we found that AR binds directly to promoters of multiple key transcriptional regulators of T cell exhaustion, including Tcf7 and Tox. Through identifying the genome-wide targets of AR in CD8 +TILs, we characterized the cell-intrinsic mechanism by which AR regulates CD8 +T cell exhaustion. Our work suggests AR is a master transcriptional regulator that negatively impacts CD8 +T cell immunity, which may contribute to poorer survival in males and supports combining androgen deprivation therapy with immune checkpoint blockage for cancer treatment. Special Institutional Funding

Management disparities in metastatic castrate-sensitive prostate cancer (mCSPC).

79 Background: Recent approvals in management of high-volume mCSPC offer major improvements in patient outcomes. Triplet therapy combining androgen deprivation therapy (ADT) with docetaxel (D) and novel hormonal therapy (NHT) is the new standard of care in this patient population. Patients ineligible for triplet therapy should receive doublet therapy with ADT plus D or NHT based on category 1 evidence. Multiple retrospective datasets examining the “real-world” mCSPC treatment landscape note significant underutilization of therapies beyond ADT and discordance with treatment guidelines. Methods: A 15-question survey to assess management patterns was electronically distributed to various mCSPC providers in California and Washington. Results: A total of 40 responses were received, with 62.5% identifying as medical oncologists (MO), 20.0% as urologists, 5.0% as radiation oncologists, and 12.5% as advanced practitioners/other. Out of physician responders, 48.6% were academic and 51.4% were community-based. When treating newly diagnosed fit mCSPC patients, 20.0% would prescribe triplet therapy, 42.5% ADT/NHT, 5.0% ADT/D, 5.0% ADT/bicalutamide, 0% ADT alone, 10.0% other therapies, and 17.5% would refer out for therapies beyond ADT. When comparing academic versus community oncologists, 66.7% versus 0% would prescribe triplet therapy, while 22.2% versus 68.8% would prescribe ADT/NHT. Some perceived barriers to following mCSPC treatment guidelines included difficulty keeping up with rapidly evolving data/too many treatment options in 27.5%, insurance coverage concerns in 22.5%, difficulty obtaining early referrals for these therapies in 12.5%, patient factors in 10.0%, and toxicity concerns in 2.5%. When making referrals to MO, 37.5% of non-MO responders would do so at development of mCSPC and 6.3% at mCRPC. Conversely, 24.2% of MO perceived receiving referrals at development of mCSPC and 33.3% at mCRPC. Patterns of ordering genomic testing are listed, with biggest perceived barriers being cost, inadequate access to sequencing platforms and genetic counselors, lack of confidence in counseling about results, and patient refusal. Upon progression from mCSPC to mCRPC, ordering of repeat tumor biopsies would occur “sometimes” by 40.0% of providers, “rarely” by 20.0%, and “never” by 20.0%. Conclusions: Multiple provider disparities when managing mCSPC patients still exist. Our survey demonstrated higher compliance with treatment guidelines than in previous retrospective datasets, possibly due to higher proportion of academic providers. Increased provider awareness of genomic testing recommendations is also needed. [Table: see text]

Emerging Role of IGF-1 in Prostate Cancer: A Promising Biomarker and Therapeutic Target.

Prostate cancer (PCa) is a highly heterogeneous disease driven by gene alterations and microenvironmental influences. Not only enhanced serum IGF-1 but also the activation of IGF-1R and its downstream signaling components has been increasingly recognized to have a vital driving role in the development of PCa. A better understanding of IGF-1/IGF-1R activity and regulation has therefore emerged as an important subject of PCa research. IGF-1/IGF-1R signaling affects diverse biological processes in cancer cells, including promoting survival and renewal, inducing migration and spread, and promoting resistance to radiation and castration. Consequently, inhibitory reagents targeting IGF-1/IGF-1R have been developed to limit cancer development. Multiple agents targeting IGF-1/IGF-1R signaling have shown effects against tumor growth in tumor xenograft models, but further verification of their effectiveness in PCa patients in clinical trials is still needed. Combining androgen deprivation therapy or cytotoxic chemotherapeutics with IGF-1R antagonists based on reliable predictive biomarkers and developing and applying novel agents may provide more desirable outcomes. This review will summarize the contribution of IGF-1 signaling to the development of PCa and highlight the relevance of this signaling axis in potential strategies for cancer therapy.

Assessment of oligometastasis status of prostate cancer following combined robot-assisted radical prostatectomy and androgen deprivation versus androgen deprivation therapy alone using PSA percentage decline rate.

To compare the tumor control in prostate cancer patients with oligo-metastasis following combined robot-assisted radical prostatectomy and androgen deprivation versus androgen deprivation therapy alone based on total prostate-specific antigen (tPSA) assessment. Medical data of a total of 18 prostate cancer patients with oligometastasis administered in The First Affiliated Hospital of Nanchang University from March 2017 to March 2018 were prospectively collected. 10 patients received a combined therapy of robot-assisted radical prostatectomy and pharmaceutical androgen deprivation (RARP+ADT group), while 8 patients received pharmaceutical androgen deprivation therapy alone (ADT group). Then demographic characteristics, prostate volume, tumor characteristics and tPSA data were analysised and compared. Statistical analysis was performed using t-test for continuous variables and Pearson chi-square test or Fisher's exact test for categorical variables. No significant difference was found in patients' age (p = 0.075), prostate volume (p = 0.134) and number of bone metastasis (p = 0.342). Pre-treatment Gleason score was significantly lower in RA group (p = 0.003). Patients in RARP+ADT group had significantly lower pre-treatment tPSA (p = 0.014), while no statistical difference was noted in reexamined tPSA (p = 0.140) on follow-up. No statistical difference was noted in tPSA decline rates (declined tPSA value per day) in RARP+ADT and ADT group (8.1 ± 4.7 verse 7.5 ± 8.0 ng/ml/d, p = 0.853). However, tPSA percentage decline rate (declined tPSA percentage per day) was significantly higher in RARP+ADT group (11.6 ± 1.5%/d verses 2.9 ± 2.2%/d, p< 0.001). Immediate urinary continence was achieved in 9 patients (90%) upon removal of urethral catheter on post-operative day 7 in RARP+ADT group. ADT alone and in combination with RARP both provide effective tumor control in patients suffering from prostate cancer with oligometastasis. ADT combined with RARP exhibited significant advantage in PSA percentage decline rate without compromising patients' urinary continence. Long-term tumor control requires further follow-up.

7P HIFA1 inhibition as a therapeutic strategy for overcoming castration resistance in PTEN-deficient prostate cancer

Prostate cancer (PCa) is the second most commonly diagnosed neoplasia in men worldwide. The growth of prostate cancer cells is initially dependent of the activity of the androgen receptor (AR) and AR is the target of first-line prostate cancer systemic treatments. The benefit of adding neoadjuvant and adjuvant androgen deprivation therapy is well established for men with high-risk localized and advanced disease. However, some patients develop castration resistant prostate cancer, for which curative options are limited. PTEN is the most often tumor suppressor gene mutated in PCa patients. Hypoxic regions have been found in prostate adenocarcinoma, and elevated expression of hypoxia markers, including HIF1a (hypoxia-inducible factor 1A), have been shown to identify PCa patients with elevated risk of biochemical recurrence. Prostate tumors of sham-operated and castrated Pten(i)pe-/- mice, which have a prostatic luminal cell-specific inactivation of PTEN after puberty, were analyzed by droplet-based single cell-RNA sequencing. Moreover, the impact of genetic and pharmacological Hif1a inhibition was determined in castrated Pten(i)pe-/- mice by histological analyses. To gain insights on pathways driving androgen-independence in prostate tumor, we analyzed Pten(i)pe-/- mice which develop tumors that are resistant to castration. Droplet based single cell-RNA sequencing of 17265 cells from dissociated tumors of castrated and sham-operated Pten(i)pe-/- mice revealed that androgen deprivation enhances hypoxia signaling in luminal cells. Importantly, this is accompanied by the emergence of an immune-cell-related gene signature in luminal cells of castrated mice, indicating that activation of hypoxic signaling and induction of cellular plasticity are involved in castration resistance. Importantly, genetic ablation of Hif1a in prostatic tumors sensitizes them to castration, and pharmacological inhibition of Hif1a together with androgen deprivation leads to durable anti-tumoral response. Androgen deprivation in combination with HIF1 signaling inhibition is a promising therapeutic strategy for overcoming castration resistance in PTEN-deficient prostatic tumors.

1410P Real-world first-line (1L) treatment patterns in patients (pts) with high-risk nonmetastatic castration-resistant prostate cancer (nmCRPC)

Pts with nmCRPC are at high risk of developing metastases if they have a prostate-specific antigen (PSA) doubling time (PSADT) of ≤10 months (mo) or Gleason score (GS) ≥8. Combining androgen deprivation therapy (ADT) with novel hormone therapies (NHTs; apalutamide/darolutamide/enzalutamide) prolongs metastasis-free survival (MFS) and overall survival (OS) in nmCRPC, but data on use of these therapies in real-world settings are minimal. We assessed the real-world use of NHTs in men with high-risk nmCRPC in the United States.

Combining Androgen Deprivation and Immunotherapy in Prostate Cancer Treatment: A Mechanistic Approach

Due to its initial dependence on testosterone, prostate cancer patients are initially treated with androgen deprivation therapy, a form of chemical castration. However, in many cases, the cancer develops resistance to this treatment. Sipuleucel-T (Provenge), is the first live cell vaccine approved for treating patients with advanced, hormonally refractive prostate cancer. However, it has shown limited survival benefit. Recently, it has been proposed that combining Provenge with androgen deprivation may result in a better treatment outcome. Here, we develop a nonlinear dynamical systems model with a view to predicting the therapeutic potential of such a combination. Our model accounts for the mechanism of action of Provenge and the immune system response elicited by androgen deprivation. We use data from mouse xenograft experiments to calibrate and validate our model. The validated model is then used to explain the limited clinical success of Provenge, and predict optimal scheduling that maximizes the anti-tumor potential of Provenge combined with androgen deprivation. In particular, we demonstrate that the two treatments should be given concurrently, rather than sequentially, as is current practice.

Recent advances in the treatment of advanced prostate cancer: maximizing existing therapies while searching for novel solutions.

Present highlights from recent research examining treatment of advanced prostate cancer. Data are emerging that combining androgen deprivation, docetaxel, and additional androgen-receptor-targeted therapies in treatment naïve metastatic prostate cancer may be an effective strategy to improve outcomes. Genomically targeted therapies and radiopharmaceuticals continue to be evaluated in the treatment of advanced castration-resistant prostate cancer. Although no clear consensus has emerged regarding the best sequencing of available therapeutics, trial results continue to support moving available therapies earlier in the disease course. Data continue to build for novel radiopharmaceuticals soon to likely be approved for treatment of castration-resistant disease.

Abiraterone plus prednisone added to androgen deprivation therapy and docetaxel in de novo metastatic castration-sensitive prostate cancer (PEACE-1): a multicentre, open-label, randomised, phase 3 study with a 2 × 2 factorial design

Current standard of care for metastatic castration-sensitive prostate cancer supplements androgen deprivation therapy with either docetaxel, second-generation hormonal therapy, or radiotherapy. We aimed to evaluate the efficacy and safety of abiraterone plus prednisone, with or without radiotherapy, in addition to standard of care. We conducted an open-label, randomised, phase 3 study with a 2 × 2 factorial design (PEACE-1) at 77 hospitals across Belgium, France, Ireland, Italy, Romania, Spain, and Switzerland. Eligible patients were male, aged 18 years or older, with histologically confirmed or cytologically confirmed de novo metastatic prostate adenocarcinoma, and an Eastern Cooperative Oncology Group performance status of 0-1 (or 2 due to bone pain). Participants were randomly assigned (1:1:1:1) to standard of care (androgen deprivation therapy alone or with intravenous docetaxel 75 mg/m2 once every 3 weeks), standard of care plus radiotherapy, standard of care plus abiraterone (oral 1000 mg abiraterone once daily plus oral 5 mg prednisone twice daily), or standard of care plus radiotherapy plus abiraterone. Neither the investigators nor the patients were masked to treatment allocation. The coprimary endpoints were radiographic progression-free survival and overall survival. Abiraterone efficacy was first assessed in the overall population and then in the population who received androgen deprivation therapy with docetaxel as standard of care (population of interest). This study is ongoing and is registered with ClinicalTrials.gov, NCT01957436. Between Nov 27, 2013, and Dec 20, 2018, 1173 patients were enrolled (one patient subsequently withdrew consent for analysis of his data) and assigned to receive standard of care (n=296), standard of care plus radiotherapy (n=293), standard of care plus abiraterone (n=292), or standard of care plus radiotherapy plus abiraterone (n=291). Median follow-up was 3·5 years (IQR 2·8-4·6) for radiographic progression-free survival and 4·4 years (3·5-5·4) for overall survival. Adjusted Cox regression modelling revealed no interaction between abiraterone and radiotherapy, enabling the pooled analysis of abiraterone efficacy. In the overall population, patients assigned to receive abiraterone (n=583) had longer radiographic progression-free survival (hazard ratio [HR] 0·54, 99·9% CI 0·41-0·71; p<0·0001) and overall survival (0·82, 95·1% CI 0·69-0·98; p=0·030) than patients who did not receive abiraterone (n=589). In the androgen deprivation therapy with docetaxel population (n=355 in both with abiraterone and without abiraterone groups), the HRs were consistent (radiographic progression-free survival 0·50, 99·9% CI 0·34-0·71; p<0·0001; overall survival 0·75, 95·1% CI 0·59-0·95; p=0·017). In the androgen deprivation therapy with docetaxel population, grade 3 or worse adverse events occurred in 217 (63%) of 347 patients who received abiraterone and 181 (52%) of 350 who did not; hypertension had the largest difference in occurrence (76 [22%] patients and 45 [13%], respectively). Addition of abiraterone to androgen deprivation therapy plus docetaxel did not increase the rates of neutropenia, febrile neutropenia, fatigue, or neuropathy compared with androgen deprivation therapy plus docetaxel alone. Combining androgen deprivation therapy, docetaxel, and abiraterone in de novo metastatic castration-sensitive prostate cancer improved overall survival and radiographic progression-free survival with a modest increase in toxicity, mostly hypertension. This triplet therapy could become a standard of care for these patients. Janssen-Cilag, Ipsen, Sanofi, and the French Government.