Pretreatment PSA Research Articles

Stereotactic Magnetic Resonance–Guided Daily Adaptive Radiation Therapy for Localized Prostate Cancer: Acute and Late Patient-Reported Toxicity Outcomes

ObjectiveTo report acute and late bowel, urinary and sexual dysfunction patient reported outcome measures (PROMS), amongst localised prostate cancer patients who underwent Stereotactic MRI-guided daily adaptive radiotherapy (SMART). MethodsAll patients who completed a baseline 12 item Patient-Reported Outcomes Version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE), before undergoing 36.25 Gy in 5 fractions by SMART, were subsequently followed up with the same graded questionnaire at set time points. Latest PSA levels were recorded. The percentage of patients who reported no change from their baseline AE or reported a new ≥ ‘frequent’ or’ severe’ AE grade during follow up was calculated. The maximum PRO-CTCAE grade for each item was recorded for each patient. The percentage of toxicity levels for each separate AE item at set time points were calculated. ResultsThe total number of patients was 69 with a median follow-up of 27 months. Median age of cohort 73 (range 54-85). The median pre-treatment PSA, T stage and Gleason score was 7.5 mmol/l (4.5-32 mmol/l), T2b (T2-T3b) and Gleason Score of 7 (3+4, range: 6-9) respectively. No patient had biochemical failure during follow up. Regarding bowel symptoms, >80% of men reported no change from baseline toxicity during follow up. New ≥ frequent diarrhoea was reported in 9% of patients. ‘Almost constant’ diarrhoea peaked at 1 month but was absent at >33 months. Regarding urinary symptoms, increased urinary urgency was the most common complaint (39%). 20% of men reported new ≥ frequent urinary urgency incidence peaking at 1 month but absent at >33 months. New “severe” sexual dysfunction was seen in 26% of patients and was persistent at >33 months. ConclusionOur study is one the largest patient reported outcomes study post prostate SMART. It shows acceptable levels of toxicity even up to 2 years post treatment.

The effect of dose-escalation radiotherapy with simultaneous-integrated-boost on the use of short-term androgen deprivation therapy in patients with intermediate risk prostate cancer.

To compare the biochemical failure (FFBF) and prostate cancer specific survival (PCSS) rates of patients with intermediate-risk prostate cancer (IR-PC) who were treated with 6 months of androgen deprivation therapy (ADT) with 78 Gy to the prostate, those treated with ADT and focal boost (FB) of 86 Gy to intraprostatic lesion (IPL) using the simultaneous-integrated boost (SIB) technique, and those treated with SIB alone. A retrospective analysis of 320 IR-PC patients treated between January 2012 and April 2021 was performed. Patients were divided into three groups based on their treatment arm: 78 + ADT (109 patients, 34.1%), 78/86 (102 patients, 31.8%), and 78/86 + ADT. Univariable and multivariable analyses were used to determine prognostic factors for FFBF and PCSS. Median follow-up was 8.8 years. The 8-year FFBF and PCSS rates were 88.6% and 99.0%. Patients who received ADT had significantly higher pretreatment PSA levels and clinical tumor stage. Disease progression occurred in 45 patients (7.3%) at a median of 41.9 months after definitive radiotherapy (RT). Younger age, positive core biopsy (PCB) ≥ 50%, and the absence of ADT were all independent predictors of poor FFBF in multivariate analysis, whereas patients with PCB < 50% who were also given ADT had better PCSS. Patients treated with 78/86 Gy alone had worse FFBF than those treated with 78 Gy and ADT (Hazard ratio [HR] = 3.39 [95% CI = 1.46-7.88]; p = 0.005), as well as than those treated with 78/86 Gy and ADT (HR = 3.21 [95% CI = 1.23-6.46]; p = 0.009). However, FB to IPL has no effect on PCSS in multivariable analysis. There was no significant difference between treatment groups in terms of acute and late Grade ≥2 genitourinary or gastrointestinal toxicity. Our findings demonstrated that patients who received 78/86 alone did worse than patients who received ADT with either 78 or 78/86 Gy. However, because IR-PC patients are so diverse, additional prospective trials are needed to validate our findings.

Abstract 7568: Molecular effects of neo-adjuvant hormone therapy for locally advanced prostate cancer: An ancillary study of the ARNEO phase 2 trial

Abstract Intensified hormone therapy in combination with radiotherapy improves outcome for very high-risk locally advanced prostate cancer. The impact of hormone therapy with surgery, however, is uncertain. In order to understand this better, we ran an ancillary translational study on ARNEO (NCT03080116), a Phase 2 clinical trial, which randomized 89 locally-advanced prostate cancer patients to 12 weeks LHRHa +/- apalutamide (APA) followed by prostatectomy. We performed clinical-grade transcriptome-wide expression array analysis (Veracyte, Inc. San Diego, CA) of FFPE diagnostic core biopsies (N=89) and tumors removed at prostatectomy (N=32 LHRHa, N=23 LHRHa + APA). We also performed RNASeq on fresh frozen biopsies of prostatectomy tumors (N=42 LHRHa, N=45 LHRHa + apalutamide) and LHRHa-naive control cases (N=61) matched for clinical and pathological risk factors. Pre-surgery serum PSA decreased by a median of 98% (IQR:90.2-99.3) after hormone treatment. This decrease was better associated with tumor AR signaling (r2=0.11) versus pre-treatment serum PSA (r2=0.0005), or between pre-treatment serum PSA with diagnostic biopsies (r2=0.008). We confirmed APA more potently suppressed AR signaling than LHRHa alone, with no detectable difference in direction of effect for differentially regulated genes/pathways. LHRHa + APA had less residual tumor (median Residual Cancer Burden, RCB=0.48cm3) than in LHRHa (median RCB=1.7cm3) but in cases with sufficient tumor, we observed residual active AR signaling pathways at prostatectomy in both treatment arms. To orthogonally confirm this, we selected 28 ERG positive cases (by IHC pre-treatment) and found retained ERG expression in 12/13 on LHRHa and 10/15 on LHRHa + APA. Using pathway analysis in the RNAseq data, we identified LHRHa +/- APA induced down-regulation of AR, metabolic pathways, as well as DNA repair, and up-regulation of hallmark NOTCH, Hedgehog, TGF-beta, WNT and immune signaling (adjusted p-value cutoff=0.001). Comparing differentially expressed genes on RNASeq between treatment-naïve versus LHRHa +/- APA treated tumors, we observed STING1 as significantly higher in LHRHa +/- APA vs control (Wilcoxon rank sum test p-value &amp;lt;0.001). We found that expression of STING1 was positively correlated with hallmark interferon alpha response (r=0.7, rs=0.6) that was correlated with apoptosis (r=0.5, rs=0.5). Whilst we show that adding APA to LHRHa increases suppression of AR activity and ERG expression, we find that 12 weeks is insufficient to abrogate AR signaling in most tumors, despite ~98% decrease in serum PSA. We identify novel processes modulated in humans by potent suppression of androgen activity, including upregulation of STING1-type 1 interferon response as a potential key modulator of treatment effect. Citation Format: Mazlina Ismail, Wout Devlies, Marina Parry, Gaetan Devos, Stefanie Friedrich, Charles Parker, Larissa Mendes, Elai Davicioni, Mark Linch, Frank Claessens, Steven Joniau, Gerhardt Attard. Molecular effects of neo-adjuvant hormone therapy for locally advanced prostate cancer: An ancillary study of the ARNEO phase 2 trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7568.

Abstract 7652: Plasma markers of hemostasis, fibrinolysis, and angiogenesis prior to androgen deprivation therapy (ADT) in progressive prostate cancer (PC) and associations with long-term thrombotic events and survival

Abstract Background: PC is the third most common malignancy associated with thrombosis, procoagulants may play a role in tumorigenesis and progression, and patients (pts) with PC may have activation of the hemostatic system evident in plasma. The prognostic significance of these markers and their relationship to thrombotic events and overall survival (OS) are under-explored. Methods: Patients &amp;gt;18 years were included if they had progressive PC planned to start ADT, were &amp;gt;6 months from surgery or RT, with no history of prior VTE, unexplained bleeding, current or planned anticoagulation, or an additional active malignancy. Plasma samples were obtained via peripheral venipuncture in tubes containing 3.2% sodium citrate and immediately placed on ice. Samples were analyzed for D-dimer, thrombin-antithrombin complex (TAT), IL-6, IL-8, VEGF, and tissue factor (TF) levels by ELISA. Patients had markers drawn at baseline (prior to initiation of ADT), 1 month, and 6 months after initiation. Results: 40 patients were accrued with a median age of 68 years. At baseline, 29 (73%) had presence of metastases. Baseline median PSA was 15 and median PSA doubling time was 0.32. Baseline median hemoglobin was 13.85, platelets were 218, D-dimer was 322 ng/dL, IL-6 was 0 pg/mL, IL-8 was 0 pg/mL, TAT was 3 ug/L, VEGF was 21 pg/mL, and TF was 26 pg/mL. Median follow-up was 78 months. During follow up, 35 (87.5%) had metastases. 10 (25%) had thrombotic events (6 [15%] venous, 4 [10%] arterial) at median 37 months follow up. Median baseline age of pts with subsequent thrombotic events was 74, vs 67 in those without a thrombotic event. While there was no significant difference in baseline PSA between groups with and without clotting events, pretreatment PSA doubling time was significantly lower in pts with subsequent thrombosis (0.27 vs 0.35, p=0.047). Median baseline D-dimer and TF were higher in patients with subsequent thrombosis (D-dimer: 516 vs 282, p=0.10; TF: 36 vs 24, p=0.12). In univariate analysis, baseline IL-6 and VEGF were associated with OS (IL-6: HR=1.05, 95% CI [1.01,1.09], p=0.025; VEGF: HR=1.02, 95% CI [1.00,1.03], p=0.028). When controlling for presence of metastasis, baseline TAT was associated with OS (HR=1.05, 95% CI [1.00,1.11], p=0.055). Conclusions: Plasma markers of hemostatic activation, fibrinolysis, and angiogenesis prior to initiation of ADT are associated with subsequent thrombotic events and overall survival years later. Further analysis will examine how these markers change over time with hormonal therapy. Citation Format: Jessica S. Palmer, Charlene Thomas, Nicole Jacobs, David Nanus, Scott T. Tagawa. Plasma markers of hemostasis, fibrinolysis, and angiogenesis prior to androgen deprivation therapy (ADT) in progressive prostate cancer (PC) and associations with long-term thrombotic events and survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7652.

21 Gy single fraction prostate HDR brachytherapy: 5-year results of a single institution prospective pilot study

PURPOSETo present the outcome and toxicity results of a prospective trial of 21 Gy single fraction high-dose-rate (HDR) brachytherapy for men with low- or intermediate-risk prostate cancer. METHODS AND MATERIALSPatients were treated according to an IRB-approved prospective study of single fraction HDR brachytherapy. Eligible patients had low- or intermediate-risk prostate cancer with tumor stage ≤ T2b, PSA ≤ 15, and Gleason score ≤ 7. Patients underwent trans-rectal ultrasound-guided trans-perineal implant of the prostate followed by single fraction HDR brachytherapy to a dose of 21 Gy. The primary endpoint was grade ≥ 2 urinary/GI toxicity rates. RESULTSTwenty-six patients were enrolled with a median follow up of 5.1 years and median age of 64 years. 88.5% of patients had T1 disease, 15.4% had Gleason score 6 (84.6% Gleason 7), and median pre-treatment PSA was 5.0 ng/mL. Acute and chronic grade ≥ 2 urinary toxicity rates were 38.5% and 38.5%, respectively. There were no grade ≥ 2 acute or chronic GI toxicities. Six (23.1%) patients experienced biochemical failure, six (23.1%) patients experienced radiographic local failure, and five (19.2%) patients had biopsy-proven local failure. No patients developed regional lymph node recurrence or distant metastasis. 5-year overall survival and cause-specific survival were 96.2% and 100%, respectively. CONCLUSIONS21 Gy single fraction HDR brachytherapy was associated with modestly higher-than-anticipated chronic urinary toxicity, as well as high biochemical and local failure rates. The results from this prospective pilot study do not support the use of this regimen in standard clinical practice.

Clinical Outcomes of Prostate SBRT Using Non-adaptive MR-Guided Radiotherapy.

Stereotactic body radiotherapy (SBRT) is widely used for localized prostate cancer and implementation of MR-guided radiotherapy has the advantage of tighter margins and improved sparing of organs at risk. Here we evaluate outcomes and time required to treat using non-adaptive MR-guided SBRT (MRgSBRT) for localized prostate cancer at our institution. From 9/2019 to 11/2021 we conducted a retrospective review of 80 consecutive patients who were treated with MRgSBRT to the prostate. Patients included low (LR) (5%), favorable intermediate (FIR) (40%), unfavorable intermediate (UIR) (49%), and high risk (HR) (6%). Short-term androgen deprivation therapy was used in 32% of patients. Target volumes included prostate gland and proximal seminal vesicles with an isotropic 3mm margin. Treatment was prescribed to 36.25 Gy in 5 fractions every other day with urethral sparing. Hydrogel spacer was used in 18% of patients. Time on the linac was recorded as beam on time (BOT) plus total treatment time (TTT) including gating. Analyzed outcomes included PSA response and patient reported outcomes scored by the American Urological Association (AUA) questionnaire and toxicity per CTCAE v5. General linear regression model was used to analyze factors affecting PSA and AUA in longitudinal follow up, and chi-square test was used to assess factors affecting toxicity. Median follow up was 19.3months (3.8 - 36.6). Median BOT was 4.6min (2.6 - 7.2) with a median TTT of 11 min (7.6 - 15.8). Pre-treatment vs post-RT median PSA was 6.36 (2.20 - 19.6) vs 0.85 (0.19 - 3.6), respectively (P < 0.001). PSA decrease differed significantly when patients were stratified by risk category, favoring LR/FIR vs UIF/HR group (P = 0.019). Four (5%) patients experienced a biochemical failure (BCF), with a median time to BCF of 20.4months (7.9 - 34.5). Median biochemical failure free survival (BCFFS) was not reached, with 2-yr and 4-yr BCFFS of 97.1% and 72.1%, respectively. Patients with LR/FIR disease had 100% 2-yr and 4-yr BCFFS, whereas patients with UIF/HR had 95% and 41% 2-yr and 4-yr BCFFS (P = 0.05). Mean pre-treatment AUA was 7.3 (1 - 25) vs 11.3 (1 - 26) at first follow-up; however, AUA normalized to baseline over time. Urethral Dmax ≥35Gy trended to lower AUA score at all follow-ups (P = 0.07). Forty-one (51%) patients reported grade 1-2 genitourinary toxicities at the 1 month follow up. Grade 3 toxicity (proctitis) was noted in 1 patient. There was no decrease in any grade rectal toxicity with use of hydrogel spacer (3 vs 6, P = 0.2). No grade ≥4 toxicities was observed. MRgSBRT has the potential for treatment adaptation but this comes at the cost of increased resource utilization. Our experience with non-adaptive MRgSBRT of the prostate highlights its short treatment times as well as efficacy with good PSA control and low toxicity profile.

Prospective study of HDR brachytherapy (BT), external beam radiotherapy (EBRT) and androgen deprivation therapy (ADT): 10-years experience of an MRI-guided approach

ObjectivesTo evaluate the predictive factors for biochemical failure and distant metastases in a prospective cohort of patients with localized prostate cancer treated with the combination of HDR BT and EBRT. Methods and materialsPatients with intermediate (IR) or high-risk (HR) prostate adenocarcinoma received a single fraction of HDR of 15 Gy combined with RT of 37.5 Gy in 15 fractions. ADT duration was used depending on risk-group. Descriptive analyses were performed. Univariate and multivariate Hazard Ratios were obtained. Finally, the Kaplan-Meier model was used to describe the survival of the events of interest. Results309 patients were treated prospectively (199 were IR and 110 HR). Median age was 72 years; 58.3 % were MRI stage ≤ T2c, 34.1 % T3a and 7.6 % T3b; ISUP-grade 1–3 in 78.9 % and ISUP 4–5 in 21.1 %. 71.8 % of patients had ≤ 50 % positive-cores in biopsy and 28.2 % had > 50 %. Median pre-treatment PSA was 9.9 ng/mL. After a median follow-up of 88 months, 41 patients presented biochemical failure and 18 developed distant metastases. Multivariate cox-regression analyses found that MR-T3b Stage (HR 3.88, p = 0.001) and ADT use (HR 3.99, p = 0.03) were the only predictive factors for biochemical failure and the number of positive cores (>50 %) the only independent predictive factor of distant metastases (HR 4.36, p = 0.002). ConclusionsPatients with mpMRI evidence of invasion of the SV and involvement of more than 50% of the cores in the prostate biopsy are patients with a higher risk of presenting a biochemical recurrence or developing metastasis due to their prostate cancer, respectively.

Patient adherence and early biochemical outcomes following relugolix with stereotactic body radiation therapy (SBRT) for unfavorable prostate cancer.

526 Background: Prostate SBRT offers an abbreviated treatment course with comparable efficacy to conventional radiotherapy. Injectable GnRH receptor agonists have been shown to improve cancer control when combined with radiotherapy. Relugolix is a new oral GnRH receptor antagonist which achieves rapid, sustained testosterone suppression. This prospective study sought to evaluate early testosterone suppression and PSA response following Relugolix and SBRT for unfavorable prostate cancer. Methods: This prospective study sought to evaluate early testosterone suppression and PSA response following Relugolix and SBRT for unfavorable prostate cancer. Relugolix was initiated at least 2 months prior to SBRT. PSA and total testosterone levels were obtained prior to and 1-4 months post SBRT. Profound castration was defined as serum testosterone &lt; 20 ng/dL. Poor drug adherence was delineated as failure to reach profound castration. PSA nadir was defined as the lowest PSA value within 4 months of completion of SBRT. Per prior trials, we examined the percentage of patients who achieved PSA level of ≤ 0.5 ng/mL and &lt; 0.2 ng/mL during the first 4 months post SBRT. Results: Between July 2021 and January 2023, 52 men were treated at Georgetown with Relugolix (4-6 months) and SBRT (36.25-40 Gy in 5 fractions) per an institutional protocol (IRB 12-1775). Median age was 71 years. 26.9% of patients were black and 28.8% were obese (BMI ≥30 kg/m2). The median pretreatment PSA was 9.1 ng/ml. 67% of patients were &gt; Grade Group 3. 44 patients were intermediate- and 8 were high-risk. The disease volume was high (mean 43.6% of total cores involved). Patients initiated Relugolix at a median of 3.6 months prior to SBRT with a median of 6.2 total months. 92.3%of patients achieved profound castration during Relugolix treatment. Poor drug adherence was observed in 2 patients. A third patient chose to discontinue Relugolix due to side effects. By post-SBRT month 4, 87.2% and 74.4% of patients achieved PSA levels ≤ 0.5 ng/ml and ≤ 0.2 ng/ml, respectively. Conclusions: Relugolix combined with SBRT allows for high rates of profound castration with low early PSA nadirs. Given the potential benefits of Relugolix over injectable GnRH receptor agonists, its usage may be preferred, especially in specific patient populations (fear of needles, prior cardiovascular events). We observed a 96% compliance rate without the utilization of scheduled cues/reminders. This finding supports the notion that patients can consistently and successfully follow an oral ADT protocol in a real-world setting. Future studies should focus on barriers to medication access.

Early biochemical outcomes following neoadjuvant/adjuvant relugolix with stereotactic body radiation therapy for intermediate to high risk prostate cancer.

Injectable GnRH receptor agonists have been shown to improve cancer control when combined with radiotherapy. Prostate SBRT offers an abbreviated treatment course with comparable efficacy to conventionally fractionated radiotherapy. Relugolix is a new oral GnRH receptor antagonist which achieves rapid, sustained testosterone suppression. This prospective study sought to evaluate early testosterone suppression and PSA response following relugolix and SBRT for intermediate to high prostate cancer. Relugolix was initiated at least 2 months prior to SBRT. Interventions to improve adherence were not utilized. PSA and total testosterone levels were obtained prior to and 1-4 months post SBRT. Profound castration was defined as serum testosterone ≤ 20 ng/dL. Early PSA nadir was defined as the lowest PSA value within 4 months of completion of SBRT. Per prior trials, we examined the percentage of patients who achieved PSA level of ≤ 0.5 ng/mL and ≤ 0.2 ng/mL during the first 4 months post SBRT. Between July 2021 and January 2023, 52 men were treated at Georgetown with relugolix (4-6 months) and SBRT (36.25-40 Gy in 5 fractions) per an institutional protocol (IRB 12-1775). Median age was 71 years. 26.9% of patients were African American and 28.8% were obese (BMI ≥30 kg/m2). The median pretreatment PSA was 9.1 ng/ml. 67% of patients were ≥ Grade Group 3. 44 patients were intermediate- and 8 were high-risk. Patients initiated relugolix at a median of 3.6 months prior to SBRT with a median duration of 6.2 total months. 92.3% of patients achieved profound castration during relugolix treatment. Poor drug adherence was observed in 2 patients. A third patient chose to discontinue relugolix due to side effects. By post-SBRT month 4, 87.2% and 74.4% of patients achieved PSA levels ≤ 0.5 ng/ml and ≤ 0.2 ng/ml, respectively. Relugolix combined with SBRT allows for high rates of profound castration with low early PSA nadirs. We observed a 96% testosterone suppresion rate without the utilization of scheduled cues/reminders. This finding supports the notion that patients with localized prostate cancer can consistently and successfully follow an oral ADT protocol without daily reminders. Given relugolix's potential benefits over injectable GnRH receptor agonists, its usage may be preferred in specific patient populations (fear of needles, prior cardiovascular events). Future studies should focus on boundaries to adherence in specific underserved populations.

Risk Factors Predicting Relapse 10 Years Following Extreme Dose-Escalated SBRT for Intermediate-Risk Prostate Cancer: Is De-Intensification Feasible in Unfavorable Subgroups?

Adding short-term androgen-deprivation therapy (ADT) to radiotherapy is recommended in unfavorable intermediate-risk (UIR) prostate cancer (PCa). Data supporting the addition of ADT to stereotactic body radiotherapy (SBRT) in intermediate-risk (IR) patients are limited. Given ADT has well-documented toxicities, we sought to identify the UIR prognostic factors that predict for relapse following SBRT without ADT. We combined results from two mature multicenter trials to determine if extreme dose-escalated SBRT yielded UIR subgroups in which the omission of ADT may be considered. Between 2008 and 2011, two prospective national trials enlisted 39 centers to enroll 285 patients with IR PCa: 182 had Memorial Sloan Kettering (MSK) favorable intermediate-risk (FIR) and 103 had MSK UIF PCa. All were treated with a non-coplanar robotic SBRT platform using real-time tracking of implanted fiducials. Two dose regimens were used: 40Gy in 5 fractions of 8Gy, and 38Gy in 4 fractions of 9.5Gy. ADT was not allowed. Univariate and multivariate analyses using a Cox proportional hazards model was performed for relapse free survival (RFS): relapse included pathologic or radiographic failure, initiation of salvage or systemic therapy, or biochemical relapse by the nadir + 2 definition. Insufficient events prevented similar analyses for local control, metastasis-free and PCa-specific survival. Examined risk factors included dose regimen, clinical T-stage, Gleason score, pre-treatment PSA, % positive biopsy cores, and number of unfavorable risk factors (URFs). All reported rates are actuarial, using Kaplan-Meier method. Median follow-up was 8.1 years. 71 patients were followed 10 years. There were no statistically significant differences in rates of toxicity, local failure, RFS, overall nor metastasis-free survival between the two dose regimens. For the entire group, 10-year overall survival was 82.9%, RFS was 83.2%, and the local failure rate was 3.6%. On univariate analysis, primary Gleason pattern 4 (PGP4) and >2 URFs predicted for RFS. On multivariate analysis, only PGP4 (hazard ratio: 3.71, p = 0.0053) was statistically significant. Examining the UIR subgroup, the only predictor for RFS was PGP4 (HR: 3.64, p = 0.0253). 10-year RFS was 88.4% for FIR and 89.1% for UIR without PGP4; this fell to 58.5% in patients with a PGP4. Following dose-escalated SBRT monotherapy, 10-year RFS rates were favorable in UIR patients without PGP4. Extreme dose escalation appeared to effectively address UIR factors correlating with tumor bulk (i.e., CS T2b, >50% cores+, PSA 10-20), but was less effective with biologically aggressive pathology (PGP4). A randomized trial, ideally including genomic classification, would be necessary to determine if dose-escalated SBRT allows de-intensification (omission of ADT) in such biologically less aggressive UIR subgroups. The high relapse rate observed in UIR patients with PGP4 affirms the need for adjuvant ADT in this subgroup.

Robotic SBRT in Prostate Cancer Patients Younger Than 50 Years Old-Updated Results.

Stereotactic Body Radiation Therapy (SBRT) is a standard therapeutic option for men with prostate adenocarcinoma. The median age of prostate cancer in the US is 66 but patients as young as 35 have been reported. Many younger patients will have surgery rather than SBRT for localized prostate cancer but some will be treated with SBRT. There is a paucity of data on the outcomes of this younger subset. This study reports updated outcomes on patients younger than 50 treated with SBRT at a single institution and compares outcomes to older patients. Between April 2006 and December 2022, 6,130 patients with prostate cancer were treated with inhomogeneous-dosed SBRT using a robotic linear accelerator. Information was available for 4,143 patients. 3568 (86.12%) of patients were treated with a median dose of 3500cGY (3500-3625) delivered over 5 consecutive fractions prescribed to the 83-85% isodose line, and the remaining 575 (13.88%) other patients receiving a median dose of 4500cGY (4500-5400) to the pelvis in conventional fractionation followed by a 3 fraction SBRT boost of 2100 cGY (1950-2100) over 3 consecutive fractions. Androgen deprivation Therapy (ADT) was prescribed in 1,035 (24.98%) of these cases. The mean age was 67.4 years old. 48 patients were younger than 50 years old (mean age 46.6). 4,095 patients were 50 or older. Patients were divided into prognostic D'Amico risk groups with 43.75%, 50.00%, 6.25% of patients falling in the low, intermediate, and high-risk stratifications in the younger cohort and 23.88%, 57.05%, 19.07% in the older cohort respectively. Pretreatment PSA was 1.72 - 43.2 (median: 5.4) in the younger group and 0.3 - 661 (median: 6.5) in the older group. In the younger group, Gleason scores were 6 in 47.92%, 7 in 47.92%, and 8-10 in 4.16%. 44 younger patients were treated with SBRT alone. 4 patients also received supplemental external beam radiation (median dose 4500cGY) and 5 patients (10.42%) received Androgen Deprivation Therapy (ADT) as part of their treatment regimen. In the older group, Gleason scores were 6 in 29.84%, 7 in 54.14%, and 8-10 in 16.02%. 3522 were treated with SBRT alone. 573 patients also received supplemental external beam radiation (median dose 4500cGY) and 1030 patients (25.15%) received Androgen Deprivation Therapy (ADT) as part of their treatment. At 75 months the 6-year biochemical relapse free survival was 95.83% in younger patients compared to 98.41% in older patients using the Phoenix definition of biochemical failure. The 6-year median post treatment PSA was 0.3 in younger patients and 0.2 in the older patients. There were no significant differences in the risk stratification between the 2 groups. This represents the largest series evaluating outcomes in very young patients treated with definitive SBRT for prostate cancer. With updated 6-year follow up, SBRT remains an effective treatment for this younger subset of patients. Continued follow up will be required to see if these results remain durable.

An MRI-Based Convolutional Neural Network to Predict Biochemical Recurrence Following Radiotherapy for Intermediate and High-Risk Localized Prostate Cancer.

The risk of biochemical recurrence (BCR) following radiotherapy (RT) for localized prostate cancer (LPCa) varies considerably within risk stratification groups defined by classic clinical and pathologic variables; there is an unmet need for low-cost tools that more robustly predict BCR and allow for individualized therapy. Published imaging-based algorithms for BCR prediction after RT are limited to hand-crafted radiomics and/or small cohorts. We aimed to develop a deep learning model to predict BCR at 5 years after RT for intermediate and high risk LPCa using pre-treatment T2-weighted (T2W) MRI. Patients with intermediate and high risk LPCa treated with radical RT at our institution between 2010 and 2015 were included. We excluded those who did not have a pre-treatment T2W-MRI and those with less than 5 years of follow-up. The Phoenix definition for BCR was used. The dataset (DS1) was split into training (70%), validation (20%), and test (10%) sets using a stratified technique. A U-Net model for prostate segmentation was trained and tested on a separate annotated prostate T2W-MRI dataset (DS2) of 225 patients from our institution. The U-Net model was then used to segment the whole prostate gland on the MRI images of DS1, and the segmented images were fed into four 2D convolutional neural networks (CNNs) using different network architectures and regularization techniques (VGG blocks with batch normalization, dropout, and max pooling layers) to predict BCR at 5 years. The CNNs were evaluated using the area under the receiver operating characteristic curve (AUC) on the test set. For benchmarking, three machine learning classifiers (Random Forest, Logistic Regression, and Support Vector Machines) were developed using the 5 most important features selected by Mean Decrease in Impurity from a set of 18 clinical variables. A total of 189 patients were included in DS1. Androgen deprivation therapy (ADT) was received by 83.6% of patients. BCR was identified in 26% of the cases. The Dice score for the U-Net segmentation model was 78% on the test set of DS2. The AUC achieved by the different CNNs for predicting BCR ranged between 0.53 and 0.75. The best performing CNN consisted of 3 convolutional layers, the first two followed by max-pooling layers, a flattening layer, a dense layer, and an output layer with softmax activation function. The best clinical model was a Random Forest algorithm with an AUC of 0.70. The selected clinical variables by decreasing feature importance were: age, time to nadir PSA, pre-treatment PSA, percentage of positive biopsy cores at diagnosis, and nadir PSA. We developed a deep learning model based on pre-treatment T2W-MRI to predict BCR at 5 years following radical RT for intermediate and high-risk LPCa. This CNN outperformed a model based on clinical variables and warrants further validation in external cohorts.

Association of Prostate Specific Antigen Kinetics after Testosterone Recovery with Subsequent Recurrence: Secondary Analysis of a Phase III Randomized Controlled Trial.

The combination of short-term androgen deprivation therapy (ST-ADT) with prostate radiotherapy (RT) is a standard of care for patients with localized prostate cancer (LPCa). After cessation of ST-ADT, it takes about 8 to 10 months for the testosterone (T) to recover to supracastrate levels, which could drive changes in PSA kinetics. It largely remains unknown whether early changes in PSA kinetics after T recovery could predict for subsequent biochemical relapse. We performed a secondary analysis of a phase III randomized controlled trial in which patients with newly diagnosed LPCa with Gleason score £7, clinical stage T1b to T3a, and PSA <30 ng/mL were randomly allocated to neoadjuvant and concurrent ADT for 6 months starting 4 months before prostate RT (76 Gy in 38 fractions over 7.5 weeks) or concurrent and adjuvant ADT for 6 months starting simultaneously with prostate RT. Clinical assessment and laboratory investigations were repeated 1 month after completion of ADT, every 4 months for the first 2 years, every 6 months for the next 3 years, and annually thereafter. We calculated the PSA doubling time (PSADT) based on PSA values up to 18 months after recovery of T to a supracastrate level (>50 ng/dL). Patients with ³3 PSA measurements after T recovery to supracastrate level were included in this analysis. Fine and Gray cumulative incidence of biochemical recurrence (BCR) was calculated in patients with PSADT at or above median versus below median. Deaths were considered as competing events. All endpoints were calculated from the time of T recovery to supracastrate level. Subdistribution hazard ratios (sHR) with 95% confidence intervals (CI) were estimated for association of PSADT with relative incidence of recurrence using competing risk regression after adjusting for tumor stage, pre-treatment PSA, Gleason score, treatment regimen, and age at randomization. Overall, 311 patients were eligible for this analysis. Median PSADT was 8 months. Cumulative incidence of BCR at 10 years was 31.0% and 20.7% in patients with PSADT <8 months and ³8 months, respectively. Longer PSADT was associated with a significantly lower risk of cumulative incidence of BCR (sHR for PSADT as a continuous variable 0.43, 95% CI: 0.28-0.66; sHR for PSADT ³8 months 0.54, 95% CI: 0.30-0.99). After adjustment for time to recovery of T to supracastrate level in addition to the aforementioned variables, longer PSADT (³8 months) was associated with lower risk of cumulative incidence of BCR (sHR: 0.53, 95% CI: 0.27-1.01). These findings suggest that early PSA kinetics within 18 months of recovery of T to a supracastrate level predict for subsequent biochemical failure. Taking account of early changes in PSA after testosterone recovery may allow for recognition of potential failures earlier in the disease course and thereby permit greater personalization of management decisions.

High-Dose Rate Brachytherapy Alone for Treatment of Unfavorable Intermediate Risk Prostate Cancer: A Propensity-Score Matched Analysis.

To demonstrate the feasibility of high-dose rate brachytherapy (HDR BT) as monotherapy for unfavorable intermediate risk (UIR) prostate cancer by comparing survival outcomes of HDR BT alone against external beam radiation therapy (EBRT) + HDR BT boost, +/- androgen deprivation therapy (ADT) using propensity-score matched (PSM) data. This retrospective study queried two data registries collecting patient data from 1991 to present. 633 patients with UIR prostate cancer treated with HDR BT alone, HDR BT+EBRT or HDR+EBRT+ADT were included. HDR BT patients received 42-45Gy/6 fractions (fx) or 27 Gy/2 fx. For HDR BT+EBRT, the HDR dose was 20-24 Gy/2 fx, 24 Gy/4 fx, or 15 Gy/1 fx. EBRT patients received 45 Gy/25 fx to the prostate +/- pelvic nodes. GU/GI toxicities were graded according to the Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Time-to-event analyses were carried out to evaluate the relationship between treatments and five primary endpoints of interest: freedom from biochemical recurrence (FFBC), freedom from distant metastasis (FFDM), freedom from local failure (FFLF), cancer specific survival (CSS), and overall survival (OS) at 5 years. PSM was performed with one-to-n matching. Logistic regression was used to estimate the respective propensity scores. The five potential confounders identified were T-stage, Gleason score, pre-treatment PSA, age, and percent positive cores. Balance was checked using the standardized mean difference of covariates. Univariate and multivariate analyses were conducted on the matched data. Toxicity analysis was performed via association between a change in pre- and post-treatment GU/GI toxicity status and the treatment group, as well as incidence of post-treatment severe GI/GU toxicity (grade 3 or higher) and the treatment group. Univariate analysis with Kaplan-Meier method and log rank test comparison between the three cohorts demonstrated no significant difference in all survival outcomes FFBC, FFDM, FFLF, CSS, OS (p = 0.15, 0.19, 0.29, 0.57, 0.28, respectively). Multivariate analysis with Cox proportional hazard regression showed no differences in HR for FFBC and OS (p = 0.95, 0.11) with addition of EBRT, or with EBRT+ADT (p = 0.17, 0.24); no fit was obtainable for FFDM, CSS, FFLF. Toxicities between the three cohorts were not significantly different when comparing post-treatment and baseline GI/GU symptoms (p = 0.53/1). No Grade 2 or 3 GI toxicities were identified, while 8%/1% HDR patients, 10%/1% HDR+EBRT patients, and 12%/2% HDR+EBRT+ADT patients experienced Grade 2/3 GU toxicities. The incidence of grade 3 or higher GU toxicities between the three groups was not significantly different (p = 0.91). This propensity-score matched study demonstrates the feasibility of HDR BT alone for effective treatment of UIR prostate cancer when compared to HDR+EBRT or HDR+EBRT+ADT, while potentially minimizing the added toxicities of EBRT and the undesirable side effect profile of ADT.

Location of Local Recurrences Post-Prostatectomy Detected by 18F-DCPFyL and Implications for Salvage Radiotherapy Target Volumes.

The use of prostate-specific membrane antigen (PSMA) PET scans have improved detection of recurrent prostate cancer for biochemical failure post-prostatectomy. The primary aim of this study is to assess the location of local recurrences for PSMA PET positive disease post-prostatectomy relative to anatomical landmarks and to inform salvage radiotherapy contouring guidelines. This is a retrospective study of patients who underwent a staging PSMA PET-CT scan with 18F-DCFPyL tracer. Eligible patients included men with biochemical recurrence (PSA >0.2ng/mL) post-prostatectomy for prostate adenocarcinoma. PSMA positive local disease (GTV) was marked on the CT scan of the PSMA PET/CT, using the PSMA PET scan fused as the secondary dataset. Reference structures were contoured to compare the positional relationship to the GTV local recurrence. Centroids of each GTV position were measured to the closest border of the reference structures and distance measured. Forty-five patients had a local recurrence on PSMA PET, 28/45 with prostate bed recurrence and 17/45 with seminal vesicle bed recurrence. The median age was 72.7 years, median pre-treatment PSA 0.515 ng/ml (0.2-11.1), pT2 in 37.8% and pT3 in 62.2, ISUP G2-3 was 66.7%, ISUP 4-5 29.6%, 67% ECE, 15.4% SV involvement and 40% positive margin. For prostate bed recurrences, 93.6% of GTVs were within 15mm from the inferior border of pubic symphysis (median 3.3mm [-9.8-15.4]), 83.9% within 10mm from the VUA (median 3.3mm [-17.4-15.9]), and 80.6% were greater than 10mm from the most superior slice of the penile bulb (median 16.4mm [1-29.5]). Laterally, 83.9% of recurrences were within 10mm of midline and 41.9% within 5mm (median 3.3mm [-13.56-11.59]) and all were contained within levator, 35.5% within 5mm (median 7.7 [1-22.6]) of the medial muscle border. 29.0% were within 5mm from the anterior edge of the rectal wall (median -7mm [-32.3-0.5]). Seminal vesicle bed recurrences were within 17.5mm of upper border of pubic symphysis for 88.9% of patients (median -4.69mm[-30.8to18.2]), 100% were more than 7.5mm inferiorly from the vas deferens (median-22.1mm[-32.7to-7.7]). Laterally, 100% recurrences were more than 7.5mm medial from obturator internus (median 5.37mm [-23.1to37.8]), and 88.9% were more than 10mm from midline (median 23.1mm [2.0-36.6]). The 18F-DCFPyL PSMA PET local recurrences can provide detailed localization of prostate bed and seminal vesicle recurrences. Our data can inform contouring guidelines for salvage radiotherapy to the prostate bed, particularly when using anatomical landmarks to define cranio-caudal extent of target volumes. For target volume laterally, the medial wall of levator ani would encompass all prostate bed recurrences, and no seminal vesicles recurrences were seen at the medial border of the obturator internus muscle.

PD15-04 PREDICTION OF PROSTATE CANCER SPECIFIC MORTALITY IN MEN UNDERGOING RADIOTHERAPY WITH OR WITHOUT HORMONAL TREATMENT, RISK STRATIFICATION BASED ON CLINICAL CHARACTERISTICS AND PSA TREATMENT RESPONSE

You have accessJournal of UrologyCME1 Apr 2023PD15-04 PREDICTION OF PROSTATE CANCER SPECIFIC MORTALITY IN MEN UNDERGOING RADIOTHERAPY WITH OR WITHOUT HORMONAL TREATMENT, RISK STRATIFICATION BASED ON CLINICAL CHARACTERISTICS AND PSA TREATMENT RESPONSE Ugo Falagario, Darko Bogdanovic, Lars Björnebo, Ahmad Abbadi, Alexander Valdman, Martin Eklund, Tobias Nordström, Markus Aly, Henrik Grönberg, Peter Wiklund, and Anna Lantz Ugo FalagarioUgo Falagario More articles by this author , Darko BogdanovicDarko Bogdanovic More articles by this author , Lars BjörneboLars Björnebo More articles by this author , Ahmad AbbadiAhmad Abbadi More articles by this author , Alexander ValdmanAlexander Valdman More articles by this author , Martin EklundMartin Eklund More articles by this author , Tobias NordströmTobias Nordström More articles by this author , Markus AlyMarkus Aly More articles by this author , Henrik GrönbergHenrik Grönberg More articles by this author , Peter WiklundPeter Wiklund More articles by this author , and Anna LantzAnna Lantz More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003262.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: A detectable PSA within 4 to 8 weeks of surgery is considered treatment failure post-radical prostatectomy and may result from persistent local disease, pre-existing metastases or residual benign tissue. Conversely guidelines do not mention any definition of PSA persistence after Radiotherapy (RT) with or without hormonal treatment (HT).This study aimed to evaluate if detectable PSA values after RT with or without HT predict PCa mortality and can be defined as treatment failure. METHODS: This population-based study included all men in Stockholm County who underwent RT with curative intent (cM0) and PSA follow-up from 2003 to 2019. All PSA values before and after treatment were retrieved from datasets of three centralized laboratories. RESULTS: 5663 patients were included. Median follow-up was 88 months (54, 128). HT was administered in 4457 (79%). Median time to PSA nadir was 6 (5, 21) months. 5089 (89.9%) reached a PSA nadir value ≤0.1 ng/ml while in 191 (3.4%) patients PSA never dropped ≤5 ng/ml. Median PSA reduction was 8 (5, 15) ng/ml. The percentage of PSA reduction from pretreatment PSA to nadir values was ≥50% in 5461 (96.4%), and <50% in 108 (1.9%).At multivariable cox regression analysis adjusting for age, pretreatment PSA, cT stage, biopsy ISUP Gleason group, HT and time to PSA nadir, we found that PSA Nadir values between 0.1-5 ng/ml (HR: 6.07; CI: 4.79,7.68) or ≥5 ng/ml (HR: 12.34; CI: 8.57,17.77) and percentage of PSA drop from pre-treatment PSA to nadir (HR per unit: 0.92; CI: 0.87,0.97) significantly predicted PCa-specific mortality (C-index of the model 0.82). Unadjusted cancer specific survival according to post treatment PSA nadir and percentage PSA reduction from pretreatment PSA are shown in Figure 1. Similar results were found in a sensitivity analysis including patients undergoing RT without HT. CONCLUSIONS: PSA persistence and low PSA drop after RT were strongly correlated to PCa-specific mortality. A PSA nadir value >0.1 ng/ml and/or any reduction of PSA nadir <50% of pretreatment PSA values may be considered a treatment failure after RT with or without HT. Predictive models including these parameters may be used to assess the need for early treatment intensification after RT. Source of Funding: This research was supported by a grant of the European Urological Scholarship Programme awarded to U.G.F. © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e419 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ugo Falagario More articles by this author Darko Bogdanovic More articles by this author Lars Björnebo More articles by this author Ahmad Abbadi More articles by this author Alexander Valdman More articles by this author Martin Eklund More articles by this author Tobias Nordström More articles by this author Markus Aly More articles by this author Henrik Grönberg More articles by this author Peter Wiklund More articles by this author Anna Lantz More articles by this author Expand All Advertisement PDF downloadLoading ...

MP73-06 OUTCOMES OF SALVAGE CRYOTHERAPY FOR BIOCHEMICAL RECURRENCE FOLLOWING PRIMARY RADIOTHERAPY IN THE MANAGEMENT OF PROSTATE CANCER - 14-YEARS SINGLE INSTITUTION EXPERIENCE

You have accessJournal of UrologyCME1 Apr 2023MP73-06 OUTCOMES OF SALVAGE CRYOTHERAPY FOR BIOCHEMICAL RECURRENCE FOLLOWING PRIMARY RADIOTHERAPY IN THE MANAGEMENT OF PROSTATE CANCER - 14-YEARS SINGLE INSTITUTION EXPERIENCE Gregory Mansour, Andrew Wang, and Robert Given Gregory MansourGregory Mansour More articles by this author , Andrew WangAndrew Wang More articles by this author , and Robert GivenRobert Given More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003341.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Salvage cryotherapy of the prostate remains a treatment option for biochemical recurrence (BCR) following either radiotherapy or other local ablative therapies of prostate cancer. Previous studies have assessed long-term oncologic results to include overall disease survival in addition to freedom from starting ADT. We aim to assess oncologic outcomes in addition to de novo stricture, fistula, urinary incontinence, and erectile dysfunction rates. METHODS: We retrospectively reviewed all men who underwent salvage cryotherapy following external beam radiation therapy (EBRT), proton beam therapy, primary cryotherapy, and brachytherapy at our institution from 2005 through 2019. Functional and oncologic outcomes were assessed. Biochemical recurrence-free survival was defined based on a combination of the Phoenix and Astro criteria and analyzed using Kaplan-Meier statistics. RESULTS: Of the total 85 patients included, 71 had primary EBRT, 9 had brachytherapy, 3 had combined EBRT and brachytherapy, and 2 had proton beam therapy. All patients had negative staging workups prior to salvage therapy. Recto-urethral fistulas occurred in 2 patients (2.3%), 21 patients (24.4%) developed urethral strictures, and 23 patients (26.7%) reported de novo incontinence requiring pads. 5- year overall biochemical free survival was 49%. A total of 53% of subjects had biochemical recurrence with a mean time of 39 months after salvage treatment. Overall cancer specific survival was 86% and metastasis free survival was 77.9%. There was not a statistically significant correlation identified between pretreatment PSA and timing to BCR R2=0.05 p=0.129. One patient did not have a PSA response after salvage cryotherapy and went on to develop metastatic disease. CONCLUSIONS: Salvage cryotherapy remains one of the few potentially curative interventions following primary radiotherapy for prostate cancer. This study highlights the necessity for patient counseling given the side effect profile. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1036 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Gregory Mansour More articles by this author Andrew Wang More articles by this author Robert Given More articles by this author Expand All Advertisement PDF downloadLoading ...

Evaluation of a novel transcriptomic tumor signature (PROSTest) as response biomarker for 177Lu-PSMA therapy in advanced prostate cancer.

183 Background: Radionuclide therapy targeting the prostate specific membrane antigen (177Lu-PSMA therapy) has proven to be an effective treatment in men with metastatic castration resistant prostate cancer (mCRPCs). Despite representing a significant therapeutic breakthrough, a critical unmet need in 177Lu-PSMA therapy, is a prognostic biomarker for treatment optimization. Imaging and standard biomarkers have limited value. The PROSTest is a new 27-gene algorithmic signature originally developed for prostate adenocarcinoma diagnosis (0 to 100, positive score ≥20). We hypothesized that PROSTest would be elevated in mCRPCs and could have utility as a biomarker for mCRPC management. Methods: Prospective enrollment of 113 mCRPC for 177Lu-PSMA therapy (KlbB-5338-0302021 study). Pathology, clinical and biomarker data were available as was PSMA-PET/CT. Blood samples were collected for PROSTest prior to therapy. Target genes were isolated and amplified using qPCR. PROSTest scores (0-100) were obtained following algorithmic analysis. Scores were correlated with mCRPC diagnosis and baseline information. Scores and standard clinical measures were evaluated as prognostic factors with survival as endpoint. Mann-Whitney U-test, Kaplan-Meier survival and Cox proportional hazards regression analysis were utilized. All data: median (IQ range). Results: 89 (79%) patients were evaluable. Age was 75 (68-80). Disease characteristics at time of diagnosis included Gleason scores 8-10 (70%) and TMM: T3-T4 tumors (67%), N1 (53%), M1 (45%). At the time of therapy all patients were metastatic and all exhibited PSMA-positive disease. The highest tumor SUVmax was 51 (28-78). PSA levels were 69ng/mL (18-305). The PROSTest score was 89 (81-92). PROSTest scores were weakly correlated with age (r=0.33, p=0.0015) but not with baseline histopathological parameters (e.g., Gleason score, TNM) or pretreatment imaging results (e.g., SUVmax). Twenty-four (27%) patients have perished. Treatment and follow-up (5 months, 3-18) are ongoing. The mOS was 15 months. No factors were associated with death as an outcome except for the PROSTest score. PROSTest scores ≥79 (based on ROC analysis) were associated with significantly increased risk for mortality (HR: 2.9, 95% CI: 1.5-7.4). The mOS was 14 months in patients with pre-therapy PROSTest scores &gt;79 compared to mOS not reached for PROSTest scores &lt;79 ( p=0.02). In the COX model, baseline PROSTest was confirmed to be significantly predictive of death despite therapy (β = 1.51, p=0.01). Conclusions: The PROSTest blood gene expression score is elevated in mCRPCs. Levels are not associated with baseline clinical, histopathological, pretreatment PSA or imaging parameters. Elevated expression (≥79) of this biomarker prior to treatment was associated with a lower survival and could be used to predict survival in patients undergoing 177Lu-PSMA.

Prognostic value of C-11 choline PET/CT scan in patients with metastatic castration resistant prostate cancer (m-CRPC) undergoing treatment with radium-223.

59 Background: Radium-223 (Ra-223) has been approved for the treatment of metastatic castration resistant prostate cancer (mCRPC) with predominantly osseous metastases. PSA flare phenomenon with Ra-223 limits the use of PSA as a prognostic tool to predict treatment response. Currently, there is a lack of diagnostic tools to predict treatment response to Ra-223. Therefore, we sought to investigate the role of mid-treatment C-11 choline PET/CT scan in predicting overall response to Ra-223. Methods: In a single institute retrospective study, we identified 32 patients who were treated with a full course of 4-6 cycles of Ra-223 and were evaluated with both PSA and C-11 choline PET scan before treatment, at mid-treatment, and after a complete course of Ra-223 between 2013 – 2018. Ra-223 was used as salvage therapy for their predominant bone disease after failing chemotherapy and 2nd generation hormone therapy. Blind repeat radiographic evaluation of patients’ scans was performed by a radiologist specialized in nuclear radiology. Favorable response was defined by achieving partial response or stable disease on imaging, while unfavorable response was defined by showing progressive disease on imaging. Results: Mean age (±SD) at starting Radium223 was 67.6 (±7.1) years, median (IQR) primary Gleason score was 9 (8-9), and median (IQR) pretreatment PSA was 13.5 (5.4-39.6) ng/ml. 78% of the patients (n=25) completed 6 cycles of Ra-223, 15% of the patients (n=5) completed 5 cycles, and 6% (n=2) received only 4 cycles. At mid-treatment scanning, 25% of the patients (n=8) showed favorable response (Group A), while 75% of the patients (n=24) showed unfavorable response (B). After a complete course of treatment, 62.5% of patients (n=5) in Group (A) continued to show favorable response, while only 8.3% of patients (n=2) in Group (B) showed favorable response (p-value= 0.0023). Conclusions: Mid-treatment evaluation with C-11 choline PET/CT scan can predict overall response to Radium 223. Patients with progressive disease at mid-treatment evaluation are very likely not going to respond to further treatment. Further studies and clinical trials are warranted.

Effect of early PSA decline after starting second-generation hormone therapy in the post-docetaxel setting on cancer-specific survival in metastatic castrate-resistant prostate cancer.

189 Background: The objective of this study is to evaluate the prognostic value of early PSA decline following initiation of second-generation hormone therapy (2nd HT), namely abiraterone acetate or enzalutamide, in the post-chemotherapy setting in patients with metastatic castrate-resistant prostate cancer (mCRPC). Methods: We retrospectively identified 75 m-CRPC patients treated with 2nd HT following docetaxel failure (defined as PSA rise and radiographic progression). Patients were categorized into two groups based on first PSA within 3 months after initiation of therapy: PSA reduction ≥ 50% (Group A) and PSA reduction &lt; 50% (Group B). The primary endpoint was cancer-specific mortality and the secondary endpoint was radiographic progression free survival. Results: There were 75 patients (52 in group A, 23 in group B) in the analytic cohort. Baseline clinical and demographic characteristics, including median age, primary Gleason score risk group, median pre-treatment PSA, disease burden, site of metastases, and pre-treatment ECOG score were not statistically different between the two groups. PSA reduction ≥50% was significantly associated with decreased risk of radiographic disease progression (HR 0.41, 95%CI 0.21-0.80, p = 0.0113) as well as decreased risk of cancer-specific mortality (HR 0.29, 95%CI 0.09-0.87, p = 0.0325). Conclusions: PSA reduction ≥50% within 3 months of starting 2nd HT for patients with mCRPC who have failed first-line docetaxel is associated with significantly improved 3-year cancer-specific mortality and progression free survival. Our data supports the use of PSA as an early prognosticating marker for patient outcomes on this second line therapy. [Table: see text]