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Purpose Cabazitaxel 25 mg/m2 (C25) significantly improved overall survival (OS) versus mitoxantrone ( P < .001) in postdocetaxel patients with metastatic castration-resistant prostate cancer (mCRPC) in the phase III TROPIC study. The phase III PROSELICA study ( ClinicalTrials.gov identifier: NCT01308580) assessed the noninferiority of cabazitaxel 20 mg/m2 (C20) versus C25 in postdocetaxel patients with mCRPC. Methods Patients were stratified by Eastern Cooperative Oncology Group performance status, measurability of disease per Response Evaluation Criteria in Solid Tumors (RECIST), and region, and randomly assigned to receive C20 or C25. To claim noninferiority of C20 (maintenance of ≥ 50% of the OS benefit of C25 v mitoxantrone in TROPIC) with 95% confidence level, the upper boundary of the CI of the hazard ratio (HR) for C20 versus C25 could not exceed 1.214 under a one-sided 98.89% CI after interim analyses. Secondary end points included progression-free survival, prostate-specific antigen (PSA), tumor and pain responses and progression, health-related quality of life, and safety. Results Overall, 1,200 patients were randomly assigned (C20, n = 598; C25, n = 602). Baseline characteristics were similar in both arms. Median OS was 13.4 months for C20 and 14.5 months for C25 (HR, 1.024). The upper boundary of the HR CI was 1.184 (less than the 1.214 noninferiority margin). Significant differences were observed in favor of C25 for PSA response (C20, 29.5%; C25, 42.9%; nominal P < .001) and time to PSA progression (median: C20, 5.7 months; C25, 6.8 months; HR for C20 v C25, 1.195; 95% CI, 1.025 to 1.393). Health-related quality of life did not differ between cohorts. Rates of grade 3 or 4 treatment-emergent adverse events were 39.7% for C20 and 54.5% for C25. Conclusion The efficacy of cabazitaxel in postdocetaxel patients with mCRPC was confirmed. The noninferiority end point was met; C20 maintained ≥ 50% of the OS benefit of C25 versus mitoxantrone in TROPIC. Secondary efficacy end points favored C25. Fewer adverse events were observed with C20.

450 Background: 1L pembro is approved in advanced UC for cisplatin-ineligible pts with PD-L1 combined positive score (CPS) ≥10 and any platinum-ineligible pts regardless of CPS in the United States based on single-arm trial data. In the phase III KEYNOTE-361 study, 1L pembro + chemo did not statistically significantly improve PFS or OS vs chemo for pts with advanced UC; formal testing of 1L pembro vs chemo was not performed. We present an exploratory analysis of outcomes with pembro vs chemo for choice-of-carboplatin (carbo) pts in KEYNOTE-361 (NCT02853305). Methods: At randomization, choice of platinum agent (cisplatin or carbo) plus gemcitabine for each pt was selected based on investigator’s assessment of cisplatin ineligibility. ORR/DOR per RECIST v1.1 by blinded independent central review and OS were determined for all pts selected for carbo (“choice-of-carbo”) and also choice-of-carbo pts with CPS ≥10. Risk difference assessment for select AEs for pembro vs chemo was conducted in choice-of-carbo pts who received ≥1 dose study treatment. Results: As of Apr 29, 2020, the median (range) time from randomization to data cutoff in the full study cohort was 31.7 (22.0-42.3) mo. At randomization, renal impairment was the most common reason for choice of carbo by investigators (36% of all pts). 170 choice-of-carbo pts were randomized to the pembro arm, and 196 choice-of-carbo pts to the chemo arm. Median OS in this subgroup was 14.6 mo with pembro vs 12.3 mo with chemo (HR 0.83 [95% CI 0.65-1.06]). 18-mo OS rate was 42% with pembro vs 40% with chemo. ORR to pembro vs chemo was 27.6% vs 41.8%. Median (range) DOR with pembro vs chemo was not reached (NR) (3.2+-36.1+ mo) vs 6.3 (1.8+-33.8+) mo. 84/170 (49%) and 89/196 (45%) choice-of-carbo pts in the pembro and chemo arms, respectively, had CPS ≥10. In this subgroup, median OS was 15.6 mo with pembro vs 13.5 mo with chemo (HR 0.82 [95% CI 0.57-1.17]). 18-mo OS rate was 44% with pembro vs 43% with chemo. ORR to pembro vs chemo was 29.8% vs 46.1%. Median (range) DOR with pembro vs chemo was NR (4.2-36.1+ mo) vs 8.3 (2.1+-33.8+) mo. Among treated pts (N=166 for pembro, N=190 for chemo), 112 pts (68%) in the pembro arm and 163 pts (86%) in the chemo arm had grade 3-5 AEs of any cause. Pembro was associated with a higher risk of pruritus, while chemo was associated with a higher risk of decreased white blood cell, neutrophil, and platelet counts, nausea, thrombocytopenia, neutropenia, and anemia. Conclusions: Due to the trial design, this subset was not statistically tested and is exploratory. Median OS and 18-mo OS rates did not appear markedly different in the two arms; some parameters such as DOR favored pembro, although longer follow-up is needed to determine median DOR for pembro. The PD-L1 CPS ≥10 did not clearly enrich for responders to pembro in choice-of-carbo pts. Pembro was associated with a lower rate of grade 3-5 AEs of any cause than chemo. Clinical trial information: NCT02853305.

448 Background: 1L pembro + chemo did not show statistically superior PFS and OS vs chemo for pts with advanced UC in the phase III KEYNOTE-361 study; OS for pembro vs chemo was not formally tested. We analyzed PFS2 (time from randomization to progressive disease [PD] on first subsequent therapy, or death from any cause, whichever occurs first) by study treatment and subsequent therapy in KEYNOTE-361 (NCT02853305) to determine the effects, if any, of therapy sequence on PFS2. Methods: PFS2 was estimated for pts in each treatment arm, who received any subsequent therapy including any anti–PD-(L)1, any therapy other than anti–PD-(L)1, or no therapy. These were exploratory analyses; no formal comparisons were done. Results: 1010 pts were randomized: 351 pts to receive pembro + chemo, 307 to pembro, and 352 to chemo. As of Apr 29, 2020, the median (range) time from randomization to data cutoff was 31.7 (22.0-42.3) mo. Subsequent therapy was received by 124/351 (35%), 126/307 (41%), and 215/352 (61%) pts in the pembro + chemo, pembro, and chemo arms, respectively. Subsequent anti–PD-(L)1 therapy was received by 169/352 (48%) pts in the chemo arm vs 23/351 (7%) in the pembro + chemo arm and 14/307 (5%) in the pembro arm. Of pts in the pembro arm who received subsequent therapy, >90% received 2L cisplatin-based or carboplatin-based treatment. Median (m) PFS2 (95% CI) for all pts by treatment arm was 14.1 mo (12.6-16.2) with pembro + chemo, 10.9 mo (9.5-12.9) with pembro, and 10.4 mo (9.8-11.2) with chemo. Across treatment arms, pts in the pembro + chemo arm had the longest mPFS2 with any subsequent therapy (14.5 mo [95% CI 13.1-16.6]) (Table). Pts in the pembro arm who received no subsequent therapy had a longer mPFS2 (12.9 mo [95% CI 8.1-17.9]) vs pts in the chemo arm who received no subsequent therapy (9.4 mo [95% CI 7.6-10.6]). Finally, pts treated with 1L pembro in the trial followed by 2L therapy other than anti−PD-(L)1 had comparable mPFS2 (10.2 mo [95% CI 8.6-12.1]) to pts treated with 1L chemo in the trial followed by 2L anti−PD-(L)1 (11.1 mo [95% CI 10.2-12.9]). Conclusions: In this exploratory analysis, treatment sequence of chemo followed by anti−PD-(L)1 upon PD vs anti–PD-(L)1 followed by chemo upon PD did not appear to impact mPFS2. Among pts who did not receive 2L therapy, 1L pembro appeared to be associated with longer mPFS2 than chemo, potentially driven by long-term responders to pembro. Clinical trial information: NCT02853305 . [Table: see text]

439 Background: The phase III KEYNOTE-361 study examined the efficacy and safety of 1L pembro + chemo or pembro alone vs chemo for pts with advanced UC. The PFS and OS benefit of pembro + chemo vs chemo did not reach statistical significance; no further formal tesing was done. We present an exploratory analysis of OS by subsequent therapy in KEYNOTE-361 (NCT02853305) to assess how 1L and 2L therapy selection affected survival outcomes; no formal comparisons were conducted. Methods: OS was estimated for pts by whether they received subsequent therapy, and by whether subsequent therapy included an anti–PD-(L)1 agent. Results: 351 pts were randomized to pembro + chemo, 307 pts to pembro, and 352 pts to chemo. As of Apr 29, 2020, the median (range) time from randomization to data cutoff was 31.7 (22.0-42.3) mo. 124/351 pts (35%) in the pembro + chemo arm, 126/307 pts (41%) in the pembro arm, and 215/352 pts (61%) in the chemo arm received any subsequent therapy. Similar rates of subsequent therapy (pembro + chemo: 32%; pembro: 43%; chemo: 59%) were observed for pts who experienced progressive disease (PD) by blinded independent central review (BICR). A higher rate of pts (169/352 [48%]) in the chemo arm received subsequent anti–PD-(L)1 therapy than in either the pembro + chemo arm (23/351 [7%]) or pembro arm (14/307 [5%]). Due to the small pt numbers, pts in the pembro + chemo or pembro arms who received subsequent anti−PD-(L)1 were not considered further. This analysis included all pts who received 2L therapy (465/1010 pts [46%]); the rate of 2L therapy was similar in pts with PD by BICR (274/615 [45%]). Chemo agents alone or in combination, specifically carboplatin, cisplatin, docetaxel, doxorubicin, gemcitabine, and paclitaxel, were the most commonly received subsequent therapies for pts who did not receive anti–PD-(L)1 in 2L. Pts who received 1L chemo followed by subsequent anti–PD-(L)1 had longer mOS (19.1 mo [95% CI 16.2-22.2]) than pts with 1L pembro followed by 2L therapy not including an anti−PD-(L)1 agent (16.0 mo [95% CI 11.8-19.2]) (Table). Conclusions: In this exploratory analysis, favorable survival outcomes were observed for pts who received 1L chemo followed by anti–PD-(L)1 compared with pts who received 1L pembro followed by 2L therapy not including an anti–PD-(L)1 agent. These data underline the continued importance of immunotherapy as 2L therapy for advanced UC. Clinical trial information: NCT02853305 . Research Sponsor: Merck & Co., Inc[Table: see text]

435 Background: The phase III KEYNOTE-361 study compared efficacy and safety of 1L pembro + chemo or pembro vs chemo in pts with advanced UC. The trial did not meet its primary endpoints of PFS or OS superiority for pembro + chemo vs chemo; formal testing for OS for pembro vs chemo was not performed. We present a post hoc landmark analysis to examine the durability of CR/PR/SD and long-term survival in pts with CR, PR, or SD to pembro vs chemo at week 9 in KEYNOTE-361 (NCT02853305). Methods: Landmark analyses of OS by CR/PR/SD at 9 weeks after randomization in the ITT population were performed. Pts were included if they had a best response of CR/PR/SD per RECIST v1.1 by blinded independent central review at the landmark date of week 9 (first imaging assessment per study protocol). Duration of CR/PR/SD and OS were estimated by the Kaplan-Meier method. No formal comparisons were performed. Results: 307 pts were randomized to receive pembro and 352 pts to receive chemo in the KEYNOTE-361 study. As of Apr 29, 2020, the median (range) time from randomization to data cutoff was 32.5 (22.0-42.4) mo for the pembo arm and 31.4 (22.1-41.6) mo for the chemo arm. In the landmark analysis, fewer pts had CR/PR/SD at week 9 with pembro (n=137 [45%]) than with chemo (n=253 [72%]). Median (range) duration of response for pembro vs chemo was 18.7 (4.4+-35.4+) vs 12.3 (0.0+-29.7+) mo for pts with CR, and 35.0 (1.1-36.1+) vs 6.1 (0.0+-36.3+) mo for pts with PR. Median (range) duration of SD was 4.8 mo (0.0-38.2+) with pembro and 4.6 mo (0.0-16.1+) with chemo. Median OS (95% CI) for pembro vs chemo was not reached (NR) (25.5-NR) vs NR (19.1-NR) for pts with CR; NR (NR-NR) vs 14.8 mo (12.1-21.0) for pts with PR; and 18.5 mo (13.8-28.8) vs 11.1 mo (8.1-14.6) for pts with SD, respectively. Long-term OS rates were higher with pembro vs chemo across all groups (CR/PR/SD) at week 9 (Table). Conclusions: In this post hoc landmark analysis, chemo was associated with more initial responses than pembro, whereas pembro was associated with longer median duration of CR and PR, and generally longer median OS than chemo. Among pts who achieved CR/PR/SD at week 9, the relative OS benefit for pembro vs chemo increased over time. Clinical trial information: NCT02853305. [Table: see text]

TPS268 Background: Docetaxel IV and prednisone is a standard of care in mCRPC with demonstrated overall survival benefit. ModraDoc006 is a novel oral tablet formulation of docetaxel and to enhance bioavailability, it is co-administered with ritonavir (/r), an inhibitor of cytochrome p450 3A4 and P-glycoprotein. The oral combination, denoted as ModraDoc006/r, could be preferable due to patient convenience and elimination of infusion reactions and prophylactic steroids administration. Due to its weekly administration and exposure levels, increased efficacy may be demonstrated. Methods: The study is an open label 1:1 randomized phase 2b trial of ModraDoc006/r bi-daily QW versus docetaxel IV 75 mg/m2 Q3W. Thirty (30) mg ModraDoc006 combined with 200 mg /r in morning and 20 mg ModraDoc006 with 100 mg /r in evening is administered on days 1, 8 and 15 of a 21 day cycle. Safety and preliminary efficacy of ModraDoc006/r have been established in a phase Ib trial in mCRPC pts. All patients will receive 5 mg oral prednisone twice daily. Treatment is continued until progression, unacceptable toxicity or patient wish. mCRPC pts with measurable disease per RECIST 1.1, suitable for docetaxel therapy, are eligible. No prior treatment with taxanes is allowed. Primary objective is objective response rate (ORR) as assessed by investigators. Secondary objectives include PSA response, PSA-PFS, time to skeletal related events and progression, duration of response, disease control rate and safety assessments. Patient reported outcomes and health-related quality of life will be captured with treatment satisfaction and FACT-P questionnaires. It is expected that ModraDoc006/r will be at least as effective as docetaxel IV. A sample size of 50 evaluable pts per arm will evaluate an estimated ORR of 25% in each arm, with a 5% two-sided alpha and power of 83.7%. Conclusions: ModraDoc006/r represents an advance in prostate cancer therapeutics with convenience of oral administration, reduced myelosuppressive toxicity and potential improved efficacy over IV docetaxel. Clinical trial information: NCT04028388.

4519 Background: Atezo, a monoclonal antibody targeting PD-L1, is an approved therapy for locally advanced/metastatic UC based on IMvigor210 and IMvigor211 phase II and III trials. The single-arm SAUL study (NCT02928406) with a broader patient (pt) population demonstrated median overall survival (OS) of 8.7 months and a safety profile consistent with previous atezo trials. Methods: Pts with locally advanced/metastatic UC or non-UC of the urinary tract received atezo 1200 mg every 3 weeks until disease progression or unacceptable toxicity. Populations excluded from IMvigor211 (renal impairment, ECOG PS 2, treated asymptomatic CNS metastases, stable controlled autoimmune disease, concomitant steroids, HIV positive, non-UC) were eligible. The primary endpoint was safety; OS and overall response rate (ORR) were secondary endpoints. Predefined subgroup analyses included outcomes according to PD-L1 status (VENTANA SP142) and age in the overall population (and the IMvigor211-like subgroup for PD-L1). Results: Between Nov 2016 and Mar 2018, 1004 pts were enrolled; 997 received atezo. Efficacy is summarized below. Incidences of grade ≥3 treatment-related adverse events were similar irrespective of PD-L1 status (overall IC 0/1 vs 2/3: 11% vs 16%; IMvigor211-like IC 0/1 vs 2/3: 11% vs 15%) or age (≥65 y: 13%; ≥75 y: 12%; ≥80 y: 10%). Conclusions: OS and ORR appear more favorable in IC 2/3 vs IC 0/1 subgroups (overall and in the IMvigor211-like population). Atezo was effective and well tolerated across subgroups including elderly pts. Clinical trial information: NCT02928406. [Table: see text]

434 Background: Immune checkpoint inhibitors (ICI) targeting PD-1/PD-L1 have shown objective response rates (ORR) of 15-21% in PD-L1 unselected patients (pts) with platinum-refractory mUC. Overall results of RANGE, a randomized, double-blinded phase 3 trial comparing ramucirumab and docetaxel (R+D) to placebo and docetaxel (P+D) in pts with platinum-refractory mUC demonstrated an ORR of 24.5% to R+D and a statistically significant improvement in progression free survival (PFS; median 4.07 vs 2.76 mo; HR 0.757). Here we present a pre-specified subgroup analysis of pts who received a prior ICI. Methods: RANGE enrolled pts with progressive mUC during or after platinum-based chemotherapy. Additional prior treatment with one ICI was permitted. Pts were randomized (1:1) to receive D 75 mg/m2 up to 10 cycles with R 10 mg/kg or P on day 1 of a 21-day cycle until disease progression or other discontinuation criteria. Primary endpoint, investigator-assessed PFS, was analyzed in the first 437 randomized pts. Secondary endpoints included overall survival, objective response, and safety. Radiographic assessment occurred every 6 weeks. Results: Thirty three of the 437 pts (8%) in the PFS population received a prior ICI. The majority (91%) received the ICI immediately following platinum and immediately prior to RANGE. Most pts received atezolizumab (55%) or pembrolizumab (36%); ORR to prior ICI was 6% and the majority (67%) had progressive disease as best response. Median duration of the ICI was 3.5 mo (IQR 1.6-5.2). Disease sites at entry onto RANGE included lymph node (79%), lung (48%), liver (39%) and bone (18%). At data cutoff, responses were achieved by 5/14 (35.7%) on R+D, compared to 2/19 (10.5%) on P+D. Responses to R+D were independent of disease site. Of pts with liver metastases, 3/8 responded to R+D compared to 0/5 on P+D. Overall, median PFS was 5.29 mo on R+D and 2.76 mo on P+D (HR 0.920). The frequency of grade ≥3 adverse events was similar between arms. Conclusions: Acknowledging limitations of sample size, R+D showed higher ORR than P+D in pts who had progressed on platinum and ICI therapy, including those with liver metastases. Clinical trial information: NCT02426125.

TPS4590 Background: Only 5%-15% of patients (pts) with advanced bladder cancer attain long-term survival with standard first-line cisplatin-based chemotherapy. Programmed death 1 (PD-1)/PD-L1 inhibitors have proven effective in recurrent, advanced urothelial cancer. Emerging data suggest these agents may also be useful in the first-line setting. In KEYNOTE-052, first-line pembro, an anti–PD-1 antibody, demonstrated antitumor activity and acceptable safety in cisplatin-ineligible pts with advanced urothelial cancer. KEYNOTE-361 (NCT02853305) is a randomized, open-label, phase 3 study of pembro with or without chemotherapy versus chemotherapy alone in pts with advanced urothelial carcinoma. Methods: Key eligibility criteria include age ≥18 years; histologically or cytologically confirmed unresectable/metastatic urothelial carcinoma of the renal pelvis, ureter, bladder, or urethra; measurable disease (RECIST v1.1, investigator review); no prior systemic chemotherapy ([neo]adjuvant platinum-based chemotherapy with recurrence > 12 months after completion is allowed); ECOG PS 0-2; and provision of a tumor sample for biomarker analyses. Pts will be randomly assigned 1:1:1 to receive pembro 200 mg every 3 weeks (Q3W), pembro + investigator’s choice of chemotherapy (gemcitabine [1000 mg/m2 on day 1 and 8 Q3W] + cisplatin [70 mg/m2 Q3W]), or chemotherapy alone. Cisplatin-ineligible pts randomly assigned to chemotherapy will receive gemcitabine + carboplatin [AUC 5 Q3W]. Chemotherapy choice must be selected before randomization. Treatment will continue until progressive disease, unacceptable adverse events (AEs), or 35 cycles of pembro (pembro arms only). Response will be assessed Q9W for the first year and Q12W thereafter. AEs will be evaluated throughout and graded per NCI CTCAE v4.0. Primary end points are progression-free survival (RECIST v1.1 per central review) and overall survival; secondary end points include objective response rate and safety and tolerability. Efficacy outcomes will be compared for pembro vs chemotherapy and pembro + chemotherapy vs chemotherapy. Enrollment is ongoing; ~990 pts will be enrolled. Clinical trial information: NCT02853305.

e16522 Background: Cs are commonly used in the treatment of mCRPC, because of their inhibitory effects on the secretion of ACTH and their palliative effects. Inhibition of ACTH results in downregulation of adrenal androgens. Cs may have a cytotoxic effect on prostate cancer cells, mediated in part by the downregulation of androgen receptors and the activation of glucocorticoid receptor-mediated signaling and downstream antiangiogenic activity. The rationale for adding Cs to D chemotherapy is for the management of symptoms and adverse events rather than for improving responses. D (without Cs) + ADT (androgen-deprivation therapy) vs ADT alone in castration-sensitive prostate cancer has resulted in significant increase in survival (NEJM, 2015). Cs has been reported to adversely influence OS during enzalutamide (NEJM, 2012). In the COU-AA-301 trial Cs use at baseline was an independent prognostic factor in multivariate analysis, but not in a stepwise selection model (JCO, 2013). Methods: We performed a retrospective analysis of 117 mCRPC pts treated with D. All pts had standard Cs premedication before D and 74 pts received prednisone 5 mg po BID, but 43 pts didn’t get continuous Cs therapy. Kaplan-Meier estimates and Cox regression model were used. Results: Pts characteristics were as follows: median age 66 yrs (range 48-81), Gleason score ≤6: 22pts, ≥7: 61pts. (34 NA). Altogether 1015 cycles of D were given, median 8 (range 2-27). Subsequent therapies were as follows: Abiraterone Acetate (AA) (75), Mitoxantrone (46), Xofigo (5), other chemotherapies (7), none (21). Pts receiving Cs had an inferior OS in all subgroups, although none was significant (Table). Only the Gleason score was an independent prognostic factor in multivariate analysis. Conclusions: Our data suggest, that D therapy withouth Cs is at least as effective as the combination. More data is neccesary to support the suspicion of negative influence of Cs on OS. Thus unnecesarry Cs treatment might be ommited. [Table: see text]

e16504Background: The COU-AA-301 trial showed that abiraterone, an oral inhibitor of cytochrome p450 CYP17, improved survival in mCRPC patients progressing after docetaxel. Methods: Our first patie...

5008Background: The Phase III TROPIC study (NCT00417079) reported a significant improvement in overall survival (OS) for C plus prednisone (P) (25 mg/m2once every 3 weeks plus 10 mg orally once daily) versus mitoxantrone plus P (Hazard Ratio [HR] 0.70; P < 0.0001) in pts with mCRPC previously treated with D. This PROSELICA study (NCT01308580) was designed to determine the relative efficacy and safety profile of C20 plus P compared with C25 plus P. Methods: In this randomized, open-label, multinational phase III study, pts with mCRPC and ECOG performance status 0–2, who progressed after treatment with D, were stratified (ECOG, RECIST, region) and randomized 1:1 to C20 or C25. To show that C20 could preserve ≥ 50% of the efficacy benefit showed by C25 in TROPIC, the HR of C20 vs C25 for the primary endpoint OS could not exceed 1.214 under 1-sided 98.89% confidence level adjusted after interim analyses. Secondary endpoints included progression free survival (PFS), safety, PSA, pain and tumor responses and qu...

261 Background: AA is approved for mCRPC, coadministered with prednisone (P) (5 mg BID) to prevent adverse events (AEs) associated with mineralocorticoid excess (ME). Lower GC doses had not previously been formally evaluated in combination with AA. Methods: This was an open-label, multicenter, phase 2 trial (NCT01867710) of asymptomatic chemotherapy-naïve mCRPC pts randomized 1:1:1:1 to AA (1000 mg QD) plus P 5 mg BID or P 5 mg QD or P 2.5 mg BID or dexamethasone (DEX) 0.5 mg QD. Pts who had previously received GC or ketoconazole were excluded. The primary end point was no ME (% of pts experiencing neither hypokalemia nor hypertension during the first 24 weeks of treatment).Secondary end points included additional safety, as well as response rate in the first 24 weeks, defined as a decline in prostate-specific antigen (PSA) ≥ 50% confirmed after 4 weeks. Results: 164 pts were randomized; 133 (81.6%) completed 24 weeks’ treatment. Median age: 70 years. Table 1 shows the rates of ME, hypertension, hypokalemia and PSA response. Changes in HbA1c values were minimal and observed in 16 (10.7%) pts. Conclusions: These data suggest that P 5 mg BID, which is approved in combination with AA, and DEX 0.5 mg QD, are effective in preventing ME-associated AEs, and that P 2.5 mg BID and P 5 mg QD can be safely used with appropriate monitoring. The suggestion of a higher PSA response rate with DEX 0.5 mg QD arm warrants further validation. Clinical trial information: NCT01867710. [Table: see text]

185 Background: Recently approved agents that target the androgen receptor pathway emphasize the importance of the persistent activity of the androgen receptor pathway in castration-resistant prostate cancer (CRPC). This raises the possibility that agents with distinct mechanisms of action may add value. GTx-758 is a selective ERα agonist that can increase SHBG and therefore reduce biologically active testosterone (T) levels. Reported here are the results, including the final primary endpoint analysis, from the 250 mg daily GTx-758 cohort of a phase II clinical trial in men on LHRH agonists that developed CRPC. Methods: This phase II open label trial (G200712, NCT01615120) treated men with high risk nmCRPC or mCRPC with T levels < 50 ng/dL who continued to receive their current form of ADT along with either 125 mg or 250 mg of GTx-758 daily, for at least 90 days. The primary endpoint was the proportion of men with a PSA decline ≥ 50% by day 90, while secondary endpoints included serum total and free T, sex hormone binding globulin (SHBG), bone turnover markers and hot flashes. Results: The 250 mg cohort (n = 39) has completed the time period for assessment of the primary endpoint. Ten of the 39 (26%) subjects exhibited a ≥ 50% decrease in PSA by Day 90, with 11/39 (28%) by Day 120, while 18/39 (46%) had PSA declines of ≥ 30%. Median SHBG levels increased 301% of baseline, confirming the principal mechanism of drug action. While on study, median free T decreases of 44% were observed across all subjects and 20/26 (77%) of the subjects with baseline serum free T levels > 0.7 pg/ml fell below this level. Therefore, 250 mg GTx-758 decreased free testosterone levels in an additive fashion to their existing LHRH therapy. The bone turnover biomarker, C-telopeptide, decreased in 79% of the subjects. 250 mg of GTx-758 has been generally well tolerated with two reported possibly drug related SAEs (VTE and MI). Conclusions: In this phase II trial, 250 mg daily GTx-758 has activity, likely mediated by lowering free T levels in patients with CRPC on LHRH therapy, and may provide amelioration of estrogen deficiency side effects associated with ADT. Clinical trial information: NCT01615120.

e16020 Background: LHRH agents used for androgen deprivation therapy (ADT) were intended to lower total testosterone (T) levels to those achieved by orchiectomy. Studies have now demonstrated that ...

e20649 Background: Bisphosphonates inhibit bone resorption and thus bone renewal by suppressing the recruitment and activity of osteoclasts. Bisphosphonates are commonly used in the treatment of mR...

201 Background: LHRH agents used for androgen deprivation therapy (ADT) were intended to lower total testosterone (T) levels to those achieved by orchiectomy. Studies have now demonstrated that a significant percentage of men do not reach orchiectomy equivalent levels and that lower serum T levels correlate with improved outcomes. GTx-758 (Capesaris®) is an oral estrogen receptor α agonist that has the potential to increase sex hormone binding globulin (SHBG), lower T levels, and ameliorate estrogen deficiency side effects associated with ADT. Methods: In an ongoing Phase 2 open label study (G200712, NCT01615120), men with high risk nmCRPC and mCRPC were continued on their current form of ADT along with either 125 mg or 250 mg of GTx-758 daily, for at least 90 days. Men at increased risk for venous thromboembolic events (VTE) are being excluded. The primary endpoint of this trial is the proportion of men with a PSA decline ≥50%, while secondary endpoints include serum total and free T, SHBG, bone turnover and hot flashes. Results: As of October 2014, the 250 mg cohort of GTx-758 has completed enrollment of 28 patients, 20 of which (1 nmCRPC and 19 mCRPC) are evaluable, having been on study ≥90 days. The principal mechanism of drug action, induction of SHBG is confirmed in these patients with median SHBG levels increasing to 297% of baseline. 250 mg GTx-758 impacts T levels in an additive fashion to LHRH agents, as while on study, 4/4 subjects with total T levels >20 ng/dL have fallen below that level and 9/10 subjects with serum free T levels >0.7 pg/ml have fallen below that level. Six of the 20 (30%) subjects have exhibited a ≥50 decrease in PSA level while 17/20 (85%) had PSA declines of varying magnitude. The bone turnover biomarker C-telopeptide decreased in 81% of the subjects. 250 mg of GTx-758 has been generally well tolerated with one reported possibly drug related SAE (VTE). Conclusions: While the Phase 2 clinical trial is ongoing, these preliminary findings indicate that 250 mg of GTx-758 is generally well tolerated and has additive activity to LHRH agents to further decrease testosterone, increase SHBG, lower PSA and decrease bone turnover. Clinical trial information: NCT01615120.

5061 Background: A global EAP was conducted to provide broader access to pts with mCRPC post-chemotherapy and to generate additional clinical efficacy and safety data for AA after registrational st...

5059 Background: The COU-AA-301 phase 3 trial showed significantly longer overall survival for AA + prednisone (P) than P alone in mCRPC pts refractory to docetaxel. This global EAP was conducted in the same setting to collect additional safety data. Methods: Open-label EAP in pts with mCRPC who progressed after 1 - 2 chemotherapy regimens (≥ 1 taxane), resided in areas where AA was unavailable and were ineligible for ongoing clinical trials of AA. Pts received AA (1000 mg PO/d) plus P (5 mg bid) in 28 d cycles until disease progression. Only serious or clinically important adverse events (AEs) were to be reported by investigators. First interim results (clinical cut-off date: December 31, 2011), reported as part of regulatory submissions, are presented. Results: 1079 pts from 15 countries were included: N. America (47%), Europe (29%), Australia (13%), Latin America (7%), and Asia (3%). Median age: 70 years (range: 47 – 93); 89% of pts were White. Median treatment exposure, incl. pts still on treatment (285 pts), was ≈ 3 months. 620 pts (58%) received ≥ 4 treatment cycles, 58 pts (5%) received ≥ 8 cycles. 441 pts (41%) reported serious or clinically important AEs, which were treatment-related in 154 pts (14%). Most common grade 3-4 AEs: ↑ALP (6%), anemia (3%), hypertension (3%), back pain (2%), and fatigue (2%). Grade 3-4 AEs of special interest were infrequent: LFT abnormalities (8%), hypertension (3%), cardiac disorders (2%), hypokalemia (< 1%), fluid retention/edema (< 1%), osteoporotic fractures (< 1%). Main reason for discontinuation (795 pts): disease progression, in 335 pts (31%). 253 pts (23%) discontinued after marketing authorization. Discontinuations due to treatment-emergent AEs, death, or withdrawal of consent were < 6% each. Conclusions: The safety profile observed in these EAP interim results was consistent with that in the COU-AA-301 randomized, placebo controlled trial conducted in the same clinical setting. No new safety signals with AA plus P were detected in this expanded patient population, which included pts from Latin America and Asia, i.e. regions that did not participate in COU-AA-301. Clinical trial information: NCT01217697.

e15530 Background: S, an active and relatively well tolerated treatment for mRCC, based on the result of a global phase III study. Methods: Retrospectively, 383 patient’s data with clear cell mRCC were collected, who were treated with S in our department between 01/nov/2005 and 31/dec/2012. S was used in 1st or 2 nd line setting. The first few dozen subjects were involved in a clinal trial after progression on first line INF therapy. In Hungary S became reimbursed by the public health insurence from 01/jan/2008 in second line, and from 01/feb/2010 in first line. All patients had definitely favorable or intermediate risk based on MSKCC risk group criteria. The starting dose of S was mostly 50 mg (schedule 4 weeks on followed by 2 weeks off). Results: We investigated the prevalence of necessity of dose reduction/modification or pretence to follow an out of ordinary application form. We registered the frequency and modality of the different types of side effects, we also studied the outcome of patients. Incidence of grade 3+4 side effects was nearly 60%. The most common side effects were fatigue (63%), mucositis/stomatitis (40,2%), hand-foot syndome (16,1%), diarrhea (34%), hypertension (34%), nausea (2%), anaemia (8,6%), leukopenia (4,6%), thrombopenia (20%) and hypothyreosis (20%). Objective response rate based on RECIST and progression-free survival (PFS) were also recorded. The efficacy of treatment was nearly similar to the global clinical trial results. CR was rare (4,2%), most of our patients had PR (31,1%) or SD (51,2%) as best response. In first line setting the results were even better (CR 10,5%, PR 44% and SD 57,5). Conclusions: S is effective and safe agent to treat patients with mRCC. Due to side effects, dose reduction / modification is often needed but rarely requires treatment discontinuation. The early detection and right management of side effects is crucial to maintain the patients on the treatment. Unfortunately the deviation from the standard care may bias the efficacy.

15581 Background: We studied the acute ototoxic effect of cisplatin in testicular cancer patients with two highly sensitive new methods for detecting high frequency hearing loss: distorsion product otoacoustic emissions (DPOAE), and spontaneous otoacoustic emissions (SOAE). Methods: Checking the acute effect, 32 (63 ears) testicular cancer patients (median age: 33 years, range: 16–59 years) were measured on the first day of their first cycle and after one week of their last cycle of cisplatin treatment. 20 mg/m2 cisplatin was administered for five days, in BEP chemotherapy regimen. The patients got on the average 2.19 cycles (2–3 cycles). We also measured the SOAE of ten healthy control persons (without chemotherapy) matching sex and age distribution of this group. A detailed medical history evaluated audiological risk factors and hearing problems. Tympanometry, DPOAE and SOAE were measured, to detect the acute changes in the inner ear after low cumulative dose of cisplatin treatment. Paired t-test, and sign test was used for statistical analysis. Results: The DPOAE did not show any changes close after cisplatin treatment (average: 2.19 cycles, 2–3 cycles), similarly to our earlier results with pure tone audiometry (PTA) and transiently evoked otoacoustic emission (TOAE). But the SOAE showed significant, early changes in incidence, shape and amplitude, in the treated group. 66% of the SOAE changed after treatment (p=0,006). In the control group (20 ears) the SOAE never changed in a three months period. (It behaves as a fingerprint) Conclusions: DPOAE did not change significantly after 2 or 3 cycles of cisplatin treatment, similarly to our earlier results with PTA, and TOAE, but the change of the SOAE-incidence, shape and amplitude close after cisplatin treatment shows acute changes in the inner ear function (first described in the literature) after administration of low cumulative dose of cisplatin. This case is the first indication of the possible clinical relevance of SOAE. Our observation has to be confirmed in further studies, with larger number of patients. No significant financial relationships to disclose.

4578 Background: Cisplatin based chemotherapy results in high cure rate in testicular cancer. The issue of toxicity is of special concern in young men with a probability of cure of at least 70–80% ...