Clinical efficacy of abiraterone and enzalutamide metastatic castration sensitive prostate cancer patients who progressed rapidly on docetaxel with a genomic analysis.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e16536-e16536
Author(s):  
Gang Chen ◽  
David James VanderWeele ◽  
Fatima Karzai ◽  
Marijo Bilusic ◽  
Munjid Al Harthy ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Trial ◽  
Median Duration ◽  
Specific Antigen ◽  
High Volume ◽  
Optimal Timing ◽  
Castration Resistant Prostate Cancer ◽  
Duration Of Treatment ◽  
Psa Progression ◽  
Low Volume

e16536 Background: Docetaxel has become a standard of care for mCSPC. Enzalutamide and abiraterone have been proven to improve survival in metastatic castration-resistant prostate cancer (mCRPC) patients. Little is known about patients who have been treated with docetaxel for mCSPC and subsequent therapeutic responses. This retrospective analysis is to evaluate the response duration of abiraterone and enzalutamide in patients who previously received docetaxel for mCSPC but developed mCRPC within 12 months. Methods: Clinical Trial NCT02649855 enrolled patients with newly diagnosed mCSPC who were treated with standard androgen deprivation therapy (ADT) and docetaxel (75 mg/m2 every 3 weeks for 6 cycles) sequenced with immunotherapy (PROSTVAC) from February 2016 to present. Patients who had progression (based on consecutive PSA rises or imaging) within 1 year of completing docetaxel and went on to subsequent abiraterone/enzalutamide were evaluated. (Note these are different PSA progression criteria than used in CHAARTED, Sweeney, NEJM, 2015). A PCR-based NGS panel (OncoMine Comprehensive Assay v3) will evaluate available tissue from these patients. Results: Of the 46 patients evaluated regardless of immunotherapy sequence, 15 (33%) went on subsequent therapy after progression on docetaxel for mCSPC, with 12 patients starting abiraterone/enzalutamide (7 with high volume disease and 5 with low volume disease). The median age was 62 (41-83) years. 6/12 patients (50%) initiated enzalutamide and 6/12 patients (50%) initiated abiraterone. The median duration of treatment for both was 7.43 (1.53 – 16.0) months, the median time to prostate-specific antigen (PSA) progression was 2 (0 – 11) months; the median duration of PSA decline was 2 months in patients with both high and low volume disease. Of note, 3/12 (25%) of patients did not have PSA response, all of them had high volume disease. Conclusions: These data from a small cohort suggest that patients who have progression within 12 months of completing docetaxel for mCSPC have limited subsequent benefit from enzalutamide or abiraterone. Additional studies are required to determine optimal timing and treatment sequence for patients with mCSPC who rapidly develop mCRPC. Clinical trial information: NCT02649855.

Efficacy of abiraterone and enzalutamide in patients who had disease progression within twelve months of completing docetaxel for metastatic castration sensitive prostate cancer.

2019 ◽  
Vol 37 (7_suppl) ◽  
pp. 241-241
Author(s):  
Gang Chen ◽  
David James VanderWeele ◽  
Fatima Karzai ◽  
Marijo Bilusic ◽  
Munjid Al Harthy ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Trial ◽  
Specific Antigen ◽  
Response Duration ◽  
Optimal Timing ◽  
Castration Resistant Prostate Cancer ◽  
Duration Of Treatment ◽  
Psa Response ◽  
Psa Progression ◽  
Low Volume

241 Background: Docetaxel is a standard of care for mCSPC. Enzalutamide and abiraterone have been proven to improve survival in metastatic castration-resistant prostate cancer (mCRPC) patients. Little is known about patients who have been treated with docetaxel for mCSPC and subsequent therapeutic responses. This retrospective analysis is to evaluate the response duration of abiraterone and enzalutamide in patients who previously received docetaxel for mCSPC but developed mCRPC within 12 months. Methods: Clinical Trial NCT02649855 enrolled patients with newly diagnosed mCSPC who were treated with standard androgen deprivation therapy (ADT) and docetaxel (75 mg/m2 every 3 weeks for 6 cycles) sequenced with immunotherapy (PROSTVAC) from February 2016 to present. Patients who had progression (based on consecutive PSA rises or imaging) within 1 year of completing docetaxel and went on to subsequent abiraterone/enzalutamide were evaluated. (Note these are different PSA progression criteria than used in CHAARTED, Sweeney, NEJM, 2015). Results: Of the 46 patients evaluated regardless of immunotherapy sequence, 15 (33%) went on subsequent therapy after progression on docetaxel for mCSPC, with 12 patients starting abiraterone/enzalutamide (6 each with high and low volume disease). The median age was 62 (41-83) years. 7/12 patients (58.3%) initiated enzalutamide and 5/12 patients (41.7%) initiated abiraterone. The median duration of treatment for both was 7.12 (1.53–16.0) months, the median time to prostate-specific antigen (PSA) progression was 5.54 (0–15.83) months; 5/12 (41.7%) of patients did not have PSA response. Of note, patients with low volume disease had a median treatment duration of 5.88 months, 3 of them did not have PSA response. Conclusions: These data from a small cohort suggest that patients who have progression within 12 months of completing docetaxel for mCSPC have limited subsequent benefit from enzalutamide or abiraterone. Additional studies are required to determine optimal timing and treatment sequence for patients with mCSPC who rapidly develop mCRPC. Clinical trial information: NCT02649855.

scholarly journals A prognostic model for stratifying clinical outcomes in chemotherapy-naive metastatic castration-resistant prostate cancer patients treated with abiraterone acetate

2017 ◽  
Vol 12 (2) ◽  
pp. E47-52 ◽  
Author(s):  
Daniel Joseph Khalaf ◽  
Claudia M. Avilés ◽  
Arun A. Azad ◽  
Katherine Sunderland ◽  
Tilman Todenhöfer ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Outcomes ◽  
Group Performance ◽  
Eastern Cooperative Oncology Group ◽  
Specific Antigen ◽  
Prognostic Index ◽  
Abiraterone Acetate ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Psa Progression

Introduction: Recently, a prognostic index including six risk factors (RFs) (unfavourable Eastern Cooperative Oncology Group performance status [ECOG PS], presence of liver metastases, short response to luteinizing hormone-releasing hormone [LHRH] agonists/ antagonists, low albumin, increased alkaline phosphatase [ALP] and lactate dehydrogenase [LDH]) was developed from the COUAA- 301 trial in post-chemotherapy metastatic castration-resistant prostate cancer (mCRPC) patients treated with abiraterone acetate. Our primary objective was to evaluate this model in a cohort of chemotherapy-naive mCRPC patients receiving abiraterone.Methods: We identified 197 chemotherapy-naive patients who received abiraterone at six BC Cancer Agency centres and who had complete information on all six RFs. Study endpoints were prostate-specific antigen (PSA) response rate (RR), time to PSA progression, time on treatment, and overall survival (OS). PSA RR and survival outcomes were compared using Χ2 test and log-rank test. Multivariable Cox proportional hazard analysis was performed to identify RFs independently associated with OS.Results: Patients were classified into good (0‒1 RFs), intermediate (2‒3 RFs), and poor (4‒6 RFs) prognostic groups (33%, 52%, and 15%, respectively). For good-, intermediate-, and poor-risk patients, PSA RR (≥50% decline) was 60% vs. 42% vs. 40% (p=0.05); median time to PSA progression was 7.3 vs. 5.3 vs. 5.0 months (p=0.02); and median OS was 29.4 vs. 13.8 vs. 8.7 months (p<0.0001).Conclusions: The six-factor prognostic index model stratifies clinical outcomes in chemotherapy-naive mCRPC patients treated with abiraterone. Identifying patients at risk of poor outcome is important for informing clinical practice and clinical trial design.

Comparison of enzalutamide and bicalutamide in patients with non-metastatic castration-resistant prostate cancer: Number needed to treat to achieve one additional patient free of clinical progression events.

2018 ◽  
Vol 36 (6_suppl) ◽  
pp. 228-228
Author(s):  
Lawrence Ivan Karsh ◽  
David F. Penson ◽  
Raoul Concepcion ◽  
Scott Flanders ◽  
Bruce A. Brown ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Absolute Risk ◽  
Specific Antigen ◽  
Additional Patient ◽  
Number Needed To Treat ◽  
Castration Resistant Prostate Cancer ◽  
Clinical Progression ◽  
Free Psa ◽  
Castration Resistant ◽  
Psa Progression

228 Background: Androgen receptor inhibitors enzalutamide (ENZA) and bicalutamide (BIC) are used to treat metastatic castration-resistant prostate cancer (mCRPC). The Phase 2 STRIVE trial included 35% non-metastatic (m0) and 65% metastatic CRPC patients (pts); ENZA reduced the risk of progression or death among pts, with an adverse event profile consistent with previous trials. The objective of this analysis was to compare ENZA with BIC using the number needed to treat (NNT) to achieve one additional pt with m0CRPC, with either a progression-free survival (PFS) event, radiographic PFS (rPFS), or free of prostate-specific antigen (PSA) progression at 1 year and 2 years. Methods: The 1- and 2-year event rates of PFS, rPFS, and progression-free PSA among pts treated with ENZA and BIC were obtained from the STRIVE trial report. The NNT was calculated as the reciprocal of the absolute risk reduction between ENZA and BIC at each time point. This represents the number of pts that need to be treated with ENZA, compared with BIC, to obtain one additional pt free of a clinical progression event. PFS was defined as the time from randomization to investigator-assessed radiographic (bone or soft tissue) progression, PSA progression, or death. The 95% confidence interval (CI) of the NNT was derived based on the 95% CI of the event rate difference. Results: The NNT to achieve one additional pt with PFS at 1 year, comparing ENZA with BIC, was 2.2 (95% CI 1.7, 3.4), suggesting that treating three pts with ENZA instead of BIC would result in one additional pt free of progression or death at the end of 1 year. The NNT to achieve one additional pt with PFS at 2 years was also 2.2 (95% CI 1.5, 3.7). For rPFS, the NNTs comparing ENZA with BIC were 4.7 (95% CI 2.8, 14.6) and 3.0 (95% CI 2.0, 6.1) at 1 and 2 years, respectively. For progression-free PSA, the NNTs were 2.0 (95% CI 1.5, 2.8) and 2.0 (95% CI 1.4, 3.3) at 1 and 2 years, respectively. Conclusions: This analysis supports the superior clinical benefit of ENZA versus BIC in men with m0CRPC. Pts treated with ENZA showed low NNT values across all clinical outcomes and time points. Clinical trial information: NCT01664923.

Phase III study of androgen deprivation therapy (ADT) with enzalutamide (ENZA) or placebo (PBO) in metastatic hormone-sensitive prostate cancer (mHSPC): The ARCHES trial.

2019 ◽  
Vol 37 (7_suppl) ◽  
pp. 687-687 ◽  
Author(s):  
Andrew J. Armstrong ◽  
Russell Zelig Szmulewitz ◽  
Daniel Peter Petrylak ◽  
Arnauld Villers ◽  
Arun Azad ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Specific Antigen ◽  
Progression Free Survival ◽  
High Volume ◽  
Phase Iii ◽  
Castration Resistant Prostate Cancer ◽  
Double Blind ◽  
Secondary Endpoints ◽  
Phase Iii Study ◽  
Grade 3

687 Background: ENZA, a potent androgen receptor inhibitor, has demonstrated benefit in men with metastatic and nonmetastatic castration-resistant prostate cancer (CRPC). Efficacy of ENZA with ADT in men with mHSPC is unknown. Methods: ARCHES is a multinational, double-blind, phase 3 study (NCT02677896). Patients (pts) with mHSPC were randomized 1:1 to ENZA (160 mg/day) + ADT or PBO + ADT, stratified by disease volume (CHAARTED criteria) and prior docetaxel therapy. Primary endpoint was radiographic progression-free survival (rPFS) assessed centrally or death within 24 weeks of treatment discontinuation. Secondary endpoints included time to prostate-specific antigen (PSA) progression, PSA and radiographic responses and overall survival (OS). Treatment continued until disease progression or unacceptable toxicity. Results: 1150 men were randomized to ENZA (n=574) or PBO (n=576); baseline characteristics were balanced between groups. Overall, 67% had distant metastasis at initial diagnosis; 63% had high volume disease, 18% had prior docetaxel. Median follow-up was 14.4 mo. ENZA + ADT significantly improved rPFS (Table); similar significant improvements in rPFS were reported in prespecified subgroups of disease volume, pattern of spread, region and prior docetaxel (HRs 0.24–0.53). Secondary endpoints improved with ENZA + ADT (Table); OS data are immature. Grade 3–4 adverse events (AEs) were reported in 23.6% of ENZA pts vs 24.7% of PBO pts with no unexpected AEs. Conclusions: ENZA + ADT significantly improved rPFS and other efficacy endpoints vs PBO + ADT in men with mHSPC, with a preliminary safety analysis that appears consistent with the safety profile of ENZA in previous CRPC clinical trials. Acknowledgements: Medical writing and editing assistance was provided by Stephanie Rippon, MBio, and Lauren Smith from Complete HealthVizion, funded by the study sponsors. This study was funded by Astellas Pharma Inc. and Medivation LLC, a Pfizer Company, the co-developers of enzalutamide. Clinical trial information: NCT02677896. [Table: see text]

KEYNOTE-046 (Part B): Effects of ADXS-PSA in combination with pembrolizumab on survival in metastatic, castration-resistant prostate cancer patients with or without prior exposure to docetaxel.

2020 ◽  
Vol 38 (6_suppl) ◽  
pp. 126-126 ◽  
Author(s):  
Mark N. Stein ◽  
Lawrence Fong ◽  
Anthony E. Mega ◽  
Elaine Tat Lam ◽  
John W. Heyburn ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Trial ◽  
Phase 1 ◽  
Specific Antigen ◽  
Prior Exposure ◽  
Clinical Activity ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Clinical Trial Information

126 Background: ADXS-PSA, an attenuated Listeria monocytogenes-based immunotherapy targeting prostate-specific antigen (PSA), is currently being evaluated in combination with pembrolizumab as a treatment for progressive metastatic castration-resistant prostate cancer (mCRPC) in the phase 1/2 KEYNOTE-046 trial (Part B). Methods: A total of 37 patients received 1x109 CFU + 200 mg pembro IV every 3 wks, for up to 2 yrs or until progression/toxicity. Results: At entry, patients were ~70 yrs with median a Gleason score of 9, and bone predominant disease (70%). MSI-High was negative in 36 pts who were able to be tested. Eighteen (48.6%) patients had received prior docetaxel, 15 pts of whom (83.3%) had also received 1-2 next generation hormonal agents (NGHAs). Nineteen (51.3%) had not received prior docetaxel and 16 of these pts (84.2%) had received 1-2 NGHAs. Overall, 16 out of 37 pts (43%) had a decreased PSA post-BL with 6/37 (16%) pts achieving a confirmed PSA reduction ≥50% from baseline. The median OS (months) for the whole group (37 pts) was 33.6 m (95% CI, range 15.4-33.6 months). The mOS for pts with and without prior exposure to docetaxel was 16 m (5.9 -33.6) and NR at 30 months of follow-up (15.4-NR), respectively. Prolonged survival was observed in pts regardless of prior therapies, microsatellite stable (MSS) status or PSA delta <50% or ≥50%. Conclusions: Results with ADXS-PSA in combination with pembrolizumab in mCRPC, with or without prior docetaxel, show promising clinical activity to be further assessed in randomized studies. Clinical trial information: NCT02325557.

Clinical activity of abiraterone acetate in patients with castration-resistant prostate cancer who received prior ketoconazole therapy.

2014 ◽  
Vol 32 (4_suppl) ◽  
pp. 99-99 ◽  
Author(s):  
Bo Zhao ◽  
Jorge A. Garcia ◽  
Timothy D. Gilligan ◽  
Brian I. Rini ◽  
Robert Dreicer
Keyword(s):  
Prostate Cancer ◽  
Specific Antigen ◽  
Underlying Mechanism ◽  
Abiraterone Acetate ◽  
Clinical Activity ◽  
Drug Discontinuation ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Psa Response ◽  
Psa Progression

99 Background: Studies have shown activity of Abiraterone acetate (AA) in patients (pts) with castration-resistant prostate cancer (CRPC) who have received prior ketoconazole. Prostate-specific antigen (PSA) response to AA in relation to previous PSA response to ketoconazole was investigated. Methods: A retrospective analysis was conducted to determine the clinical activity of AA in men with CRPC who have received prior ketoconazole therapy at our institution. Time to PSA progression (PSA TTP) was defined by PCWG2 criteria, a PSA reduction of 50% or more was considered as PSA response. Results: Thirty four pts were identified. Nineteen pts (56%) had previous PSA responses on ketoconazole, with a median PSA TTP of 11 months (95% confidence interval [CI] 6.8-19.9). Subsequently, 11 of 34 (33%) of pts achieved a PSA response on AA, with a median PSA TTP of 6 months (95% CI 4.9-9.5). Among the 19 pts having a PSA response on ketoconazole, only four (21%) pts subsequently had PSA response to AA. Two of these pts had transient PSA response with PSA TTP less than 3 months on kKetoconazole, one patient discontinued Ketoconazole due to side effects, one patient had intermittent non-castrate testosterone levels. In contrast, 7 of 15 (46.7%) pts without prior PSA response to ketoconazole subsequently achieved PSA response on AA (p=0.11). Of note, PSA reduction of less than 50% on AA was observed in 9 of 34 pts (26%), which was associated with a longer median PSA TTP compared to pts who had PSA-progressive disease (5.9 months [95% CI 3.5-7.3] vs.1.5 months [95% CI 1.0-3.5], p=0.028). Five of these nine patients had a prior PSA response to ketoconazole but required drug discontinuation for reasons other than disease progression. Conclusions: PSA response to prior ketoconazole therapy is associated with lower PSA response rate to subsequent AA. The observation suggests that there is a biologically distinct subset of patients who are ketoconazole-resistant but abiraterone-sensitive, the underlying mechanism needs to be further investigated.

Randomized phase II trial of docetaxel plus prednisolone with or without androgen deprivation treatment in castration-resistant prostate cancer.

2016 ◽  
Vol 34 (2_suppl) ◽  
pp. 217-217
Author(s):  
Jae Ho Jeong ◽  
Hyejung Hyun ◽  
In Gab Jeong ◽  
Jun Hyuk Hong ◽  
Hanjong Ahn ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Trial ◽  
Clinical Outcomes ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Randomized Phase Ii ◽  
Psa Response ◽  
Psa Progression ◽  
The Impact ◽  
Clinical Trial Information

217 Background: Androgen deprivation therapy (ADT) has been the main treatment option for patients with locally advanced or metastatic prostate carcinoma. However, the impact of continued ADT on clinical outcomes in castration-resistant prostate cancer (CRPC) patients treated with cytotoxic chemotherapy is controversial. We conducted a randomized phase II study to assess the impact of continued ADT in patients with CRPC receiving docetaxel plus prednisolone chemotherapy. Methods: Patients with CRPC were randomly assigned (in a 1:1 ratio) to receive docetaxel (75mg/m2 every 3 weeks) plus prednisolone (5mg twice daily on days 1-21) with ADT (leuprolide 11.25 mg long-acting depo every 12 weeks, ADT group) and docetaxel plus prednisolone without ADT (No-ADT group). For patients in the No-ADT group, ADT was resumed at the end of chemotherapy. The primary endpoint was time to PSA progression. Secondary objectives included PSA response rates, progression-free survival (PFS), and overall survival (OS). Suspension of leuprolide support prevented the attainment of our original goal of enrolling 80 men. Results: Between April 2011 and July 2014, 45 patients were enrolled in this study; 23 patients were randomly assigned to the ADT group and 22 to the No-ADT group. The median age was 68 years (range = 49-81) and median baseline serum PSA was 60.3 ng/mL (interquartile range = 14.7-157.3). Time to PSA progression was 6.5 months in ADT group and 4.3 months in No-ADT group, respectively (P = 0.673). PSA response rates were 55.2% and 44.8% in the ADT group and the No-ADT group, respectively (P = 0.463). The median PFS and OS were 5.3 months and 19.4 months for ADT patients and 4.3 months and 20.8 months for No-ADT patients, respectively (P = 0.608, P = 0.635). The testosterone level rose to more than the castrate level in 5 (22.7%) patients of the No-ADT group. Conclusions: Clinical outcomes were not significantly different when patients with CRPC received concurrent ADT, or were not so treated, when receiving docetaxel plus prednisolone chemotherapy. Clinical trial information: NCT01487902 Clinical trial information: NCT01487902.

Enzalutamide versus flutamide for castration-resistant prostate cancer after combined androgen blockade therapy with bicalutamide: A multicenter randomized phase II trial (OCUU-CRPC study).

2019 ◽  
Vol 37 (7_suppl) ◽  
pp. 168-168
Author(s):  
Taro Iguchi ◽  
Satoshi Tamada ◽  
Minoru Kato ◽  
Sayaka Yasuda ◽  
Yuichi Machida ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Response Rate ◽  
Specific Antigen ◽  
Distant Metastases ◽  
Phase Iii ◽  
Progression Rate ◽  
Castration Resistant Prostate Cancer ◽  
Combined Androgen Blockade ◽  
Psa Progression ◽  
Androgen Blockade

168 Background: In Asia, including Japan, combined androgen blockade (CAB) therapy with bicalutamide is widely administered for metastatic prostate cancer. Alternative anti-androgen therapy (AAT) with flutamide after CAB therapy with bicalutamide was common before the androgen receptor-targeted therapy era. The objective of the OCUU-CRPC study was to compare the efficacy and safety between second-line hormonal therapy of enzalutamide and flutamide as alternative AAT after CAB therapy that included bicalutamide in patients with CRPC. Methods: A total of 104 patients with CRPC with or without distant metastases after disease progression who received CAB therapy with bicalutamide were randomly assigned at a 1:1 ratio according to distant metastases to the enzalutamide (160 mg/day) and flutamide (375 mg/day) groups. The primary endpoint for the drug efficacy was the response rate of prostate-specific antigen (PSA; i.e., declined by ≥50%) at 3 months. Results: Between January 2015 and February 2018, 103 patients were randomly assigned, 52 to enzalutamide and 51 to flutamide. 25 (48%) and 38 (75%) patients, respectively, discontinued their assigned treatment before study end, mainly due to progressive disease. Median follow-up time was 13.4 months (IQR 9.6–23.8) in the enzalutamide group and 17.0 months (9.7–24.4) in the flutamide group. Enzalutamide resulted in significant improvements in the response rate of PSA at 3 months (84.6% vs 31.4%; p< 0.001). Enzalutamide significantly improved in all secondary endpoints: the PSA progression rate at 3 months (HR, 0.17; 95% CI, 0.05 to 0.47; p< 0.01) and at 6 months (HR, 0.22; 95% CI, 0.09 to 0.50; p< 0.01); and PSA response rate at 6 months (75.0% vs 29.4%; p< 0.01); and time to PSA progression (median: not reached vs 6.6 months; HR, 0.29; 95% CI, 0.15 to 0.54; p< 0.01). The observed adverse event profile was consistent with that from phase III enzalutamide trials. Conclusions: Enzalutamide significantly reduced risk of progression compared with flutamide in patients with CRPC after CAB therapy with bicalutamide. This trial is registered with ClinicalTrials.gov, number. Clinical trial information: NCT02346578.

A phase II study of onvansertib (PCM-075) in combination with abiraterone and prednisone in patients with metastatic castration-resistant prostate cancer.

2019 ◽  
Vol 37 (7_suppl) ◽  
pp. TPS336-TPS336
Author(s):  
David Johnson Einstein ◽  
Atish Dipankar Choudhury ◽  
Philip James Saylor ◽  
Lillian Werner ◽  
Mark G. Erlander ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Disease Control ◽  
Phase 1 ◽  
Specific Antigen ◽  
Specific Inhibitor ◽  
Circulating Tumor Dna ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Psa Progression ◽  
Hormonal Therapies

TPS336 Background: Metastatic castration-resistant prostate cancer (mCRPC) remains a leading cause of cancer-related deaths worldwide. Although abiraterone (abi) in either the castration-sensitive or castration-resistant setting increases survival, resistance is universal and limits the efficacy of subsequent hormonal therapies. Polo-like kinase 1 (PLK1) is a serine/threonine protein kinase that regulates mitotic functions and promotes the progression of cells through mitosis, and it is highly upregulated in prostate cancer following castration. PLK1 inhibition enhances the efficacy of abi in cell line models as well as patient-derived tumor xenografts via several mechanisms. Onvansertib (PCM-075; Trovagene, Inc.) is the first orally available PLK1-specific inhibitor. In phase 1 testing, onvansertib demonstrated a manageable safety profile, with transient hematologic effects as its most prominent, yet reversible, toxicity. Methods: The goal of this phase 2 study (NCT03414034) is to observe the effects of onvansertib in combination with abi + prednisone on disease control, as assessed by prostate-specific antigen (PSA) decline or stabilization after 12 weeks of study treatment, in subjects with mCRPC and early resistance to abi. Patients will be enrolled at time of PSA progression while on standard abi. A completed 3-patient safety lead-in phase tested the safety of the combination of onvansertib with abi, and the accruing expansion phase will treat 29 more patients with onvansertib (24 mg/m2 orally on days 1-5 of a 21-day cycle) plus abi (administered orally and continuously once daily with prednisone) until time of radiographic or symptomatic progression. With 32 patients, there will be 90% power to detect a change in disease-control rate from 10% (null) to 30% (alternative). Based on a Simon’s two-stage optimal design, the study will terminate early if < 2 of the first 13 patients achieve disease control. Exploratory analyses include evaluations of predictive genomic biomarkers in circulating tumor cells and circulating tumor DNA, including alterations of oncogenes and tumor suppressors implicated in PLK1 sensitivity within preclinical models. Clinical trial information: NCT03414034.

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