Pilot study of anti-prostate-specific membrane antigen (PSMA) antibody J591 for men with metastatic castration-resistant prostate cancer (mCRPC) and unfavorable circulating tumor cell (CTC) count.

2021 ◽  
Vol 39 (6_suppl) ◽  
pp. 120-120
Author(s):  
Justin M Lebenthal ◽  
Michael Sun ◽  
Jones T. Nauseef ◽  
Muhammad Junaid Niaz ◽  
Dunya Imad ◽  
...  
Keyword(s):  
Primary Endpoint ◽  
Single Agent ◽  
Circulating Tumor Cell ◽  
Post Treatment ◽  
Risk Category ◽  
Castration Resistant Prostate Cancer ◽  
Psma Pet ◽  
Pre Treatment ◽  
Ecog Ps ◽  
A Prospective Study

120 Background: Elevated CTC counts are associated with a poor prognosis in men with mCRPC. PSMA targeted radionuclide therapy has been associated with decline in CTC count, but it remains unclear whether this effect results from radionuclide-induced cytotoxicity. J591 was engineered to have antibody-dependent cytotoxicity. A subset of patients was observed to have CTC count decline following imaging with 111In-J591, so a prospective study was launched to test the hypothesis that “naked” J591 leads to CTC count decline. Methods: In a Simon 2-stage dose de-escalation study, men with progressive mCRPC and unfavorable CTC count (CellSearch > 4) received a single dose of J591. Initial dose cohort 300 mg with de-escalation to 20 mg. CTC count was re-assessed 4, 8, and 12 weeks following therapy along with PSA and standard imaging. An optional PSMA PET was included prior to treatment. The primary endpoint was proportion of subjects with conversion to favorable CTC count ( < 5 CTCs/7.5 mL blood) and/or > 30% decline from baseline within 12 weeks post-treatment. Results: 10 men were enrolled, 9 of whom were evaluable (1 died of progressive mCRPC prior to post-treatment CTC count). Median age was 71.5 years (range 60-81), 78% had prior chemo, ECOG PS 1 in 45% and 2 in 55%. 7 of 9 (78%) evaluable subjects were Halabi CALGB prognostic poor risk category and 2 (22%) intermediate. 6 of 9 had pre-treatment PSMA PET/CT (three 89Zr-J591 and three 68Ga-PSMA11). Though not required, all scans showed > 1 lesion with SUVmax > liver SUV (range 9.12-70.15). 2 of 6 in the 300 mg cohort had CTC count decline; 1 of 6 converted to favorable count (9 to 0 with decrease of 35 to 12 in other). 3 were treated with 20 mg; 1 had CTC count decline of 316 to 112, but 0 converted to favorable count. Across both cohorts, 3 of 9 had a CTC count decline at any point in time, ranging from 65-100% decline. With the pre-specified 2-stage design, enrollment was halted for futility based upon the primary endpoint of 12-week CTC count. PSA values post-treatment increased in 8 (89%) patients and remained unchanged in 1 (11%) patient. Conclusions: Single-agent anti-PSMA antibody J591 may lead to decline in CTC count, though the study did not meet its primary endpoint. A combination or maintenance approach might be preferable and is worthy of exploration.

A phase (Ph) 1b/2 study of ribociclib (R) in combination with docetaxel (D) plus prednisone (P) in metastatic castration-resistant prostate cancer (mCRPC).

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 5043-5043
Author(s):  
Ivan de Kouchkovsky ◽  
Arpit Rao ◽  
Benedito A. Carneiro ◽  
Li Zhang ◽  
Catriona Lewis ◽  
...  
Keyword(s):  
Primary Endpoint ◽  
Single Agent ◽  
Progression Free Survival ◽  
Circulating Tumor Cell ◽  
Median Number ◽  
Rank Test ◽  
Synergistic Activity ◽  
Castration Resistant Prostate Cancer ◽  
Open Label ◽  
Increased Risk

5043 Background: The survival benefit of D in mCRPC is modest. CDK4/6 inhibitors such as R have shown synergistic activity with taxanes in pre-clinical cancer models. We sought to determine the safety and efficacy of R + D + P in mCRPC patients (pts). Methods: This was a Ph 1b/2 multicenter, open-label single arm trial of mCRPC pts with progression (PD) on ≥ 1 prior androgen receptor signaling inhibitor (ARSi) who had not previously received D for mCRPC (NCT02494921). Pts were treated with escalating doses of R in combination with D + P for 6-9 cycles, followed by single agent maintenance R until radiographic or clinical PD. The Ph 2 primary endpoint was 6-month (mo) radiographic progression-free survival (rPFS) rate by PCWG2 criteria, with a target rate of 55% and null hypothesis of 35%. Ph 2 pts underwent baseline circulating tumor cell (CTC) enumeration and genome sequencing (Epic Sciences). Cox proportional hazard model and log-rank test were used to test for associations between rPFS and CTC burden and copy number (CN) variants, respectively. Results: 43 pts were enrolled from 11/2015 to 6/2019. Median age was 68 (range 55-84). 20.9% of pts had visceral metastases. 33 (77%) had PD on prior abiraterone, 27 (63%) on enzalutamide, and 17 (40%) on both. In Ph 1b, 19 pts were enrolled. In the first cohort (D 75 mg/m2 day [d] 1, R 200 mg/d d2-14 of every 21d cycle), 2 pts experienced DLTs (febrile neutropenia [FN] and grade 4 neutropenia). With an alternative dosing schema of D 60 mg/m2 on d1, and R daily on d1-4 and 8-15 of cycle, with daily G-CSF support on d5-7, the MTD was not reached and D 60 mg/m2 + R 400 mg/d was chosen as the recommended Ph 2 dose (RP2D). In total, 30 pts were treated at RP2D; median number of D cycles was 8.5 and 60% went on to receive maintenance R. The Ph 2 primary endpoint was met with a 6-mo rPFS rate of 65% (95% CI 50-85%). Median rPFS was 8.0 mos (95% CI 4.1-10.0). PSA response rate (RR) defined as ≥50% reduction was 27.6% (95% CI 12.7-47.2%) and objective RR was 30.8% (95% CI 9.1-61.4%). Among pts treated at RP2D, the most common grade ≥3 treatment-related adverse events were neutropenia (n= 11, 36.7%), lymphocytopenia (n=3, 10%); no cases of FN were observed. Baseline CTC burden was associated with an increased risk of radiographic PD or death (HR 1.038, 95% CI 1.001-1.074, p = 0.038). Pts harboring CTCs without MYC (4/11 pts) or CDK6 CN gain (7/11 pts) had prolonged rPFS compared to those with gene amplification (median rPFS 10.76 vs 4.11 mos, p = 0.03, and 7.01 vs 1.92 mos, p = 0.053, respectively). Conclusions: The combination of R + D was well tolerated and showed promising activity in mCRPC pts who had progressed on an ARSi. The Ph 2 study met its primary endpoint, with an encouraging 6-mo rPFS rate of 65%. Lack of MYC or CDK6 amplification on CTC sequencing was associated with longer rPFS. Funding: Novartis Pharmaceuticals, PCF YIA. Managed by the PCCTC. Clinical trial information: NCT02494921.

Baseline and post-treatment circulating tumor cell (CTC) counts with prostate-specific membrane antigen (PSMA)-targeted radionuclide therapy (TRT) in men with metastatic castration-resistant prostate cancer (mCRPC).

2021 ◽  
Vol 39 (6_suppl) ◽  
pp. 158-158
Author(s):  
Michael Sun ◽  
Justin M Lebenthal ◽  
Jones T. Nauseef ◽  
Muhammad Junaid Niaz ◽  
Sabrina Guervil ◽  
...  
Keyword(s):  
Radionuclide Therapy ◽  
Circulating Tumor Cell ◽  
Post Treatment ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Individual Trial ◽  
Prognostic Group ◽  
Pre Treatment ◽  
Taxane Chemotherapy ◽  
Patients Experience

158 Background: CTC counts are an independent prognostic factor in men with mCRPC; certain changes following treatment (conversion from detectable to undetectable or unfavorable to favorable) are associated with improved overall survival. Most PSMA-TRT efficacy data have focused on PSA or imaging changes. Here, we describe baseline and post-treatment CTC counts from subjects receiving PSMA-TRT. Methods: Men with mCRPC treated on prospective clinical trials of PSMA-TRT and with available CTC counts (CellSearch) were included in our analysis. Depending upon the era of the trial, post-treatment counts were performed at 4-6 (initial era) or 12 weeks (recent era) after a single cycle of PSMA-TRT (individual trial data reported elsewhere). We describe CTC counts at baseline and compare pre-treatment counts to those after PSMA-TRT. Results: 116 men treated with PSMA-TRT had baseline CTC count (90 with both pre- and post-treatment CTC). Forty-four patients (37.9%) received 177Lu-J951, 46 (39.7%) received 177Lu-PSMA-617, and 26 (22.4%) received 225Ac-J591. Median age was 71.5. Fifty-eight patients (50%) had previously received taxane chemotherapy, median PSA was 82.98 ng/mL, and 66 (56.9%) were in the high-risk Halabi (CALGB) prognostic group. Eighty-nine out of one hundred sixteen (76.7%) had detectable baseline CTC and 58/116 (50%) had unfavorable baseline CTC count. Forty-nine out of seventy (70%) had post-treatment CTC count decline, 23/70 (32.9%) converted from detectable to undetectable, and 17/47 (36.2%) converted from unfavorable to favorable. CTC changes stratified by type of PSMA-TRT are reported in the table. Conclusions: This is the largest analysis of CTC changes in patients who have received PSMA-TRT. In addition to PSA changes and other previously reported outcomes, even when low doses of radionuclide therapy as part of dose-escalation studies are included, the majority with detectable CTC counts have post-treatment CTC count decline. A significant portion of patients experience favorable CTC changes. [Table: see text]

A randomized phase II study of OGX-427 plus prednisone (P) versus P alone in patients (pts) with metastatic castration resistant prostate cancer (CRPC).

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 4514-4514 ◽  
Author(s):  
Kim N. Chi ◽  
Sebastien J. Hotte ◽  
Susan Ellard ◽  
Joel Roger Gingerich ◽  
Anthony Michael Joshua ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cancer Progression ◽  
Single Agent ◽  
Castration Resistant Prostate Cancer ◽  
Disease Response ◽  
Measurable Disease ◽  
The Difference ◽  
Ecog Ps

4514 Background: Heat Shock Protein 27 (Hsp27) is a multi-functional chaperone protein that regulates cell signaling and survival pathways implicated in cancer progression. In prostate cancer models, Hsp27 complexes with androgen receptor (AR) and enhances transactivation of AR-regulated genes. OGX-427 is a 2nd generation antisense oligonucleotide that inhibits Hsp27 expression with in vitro and in vivo efficacy and was well tolerated with single agent activity in phase I studies. Methods: Chemotherapy-naïve pts with no/minimal symptoms were randomized to receive OGX-427 600 mg IV x 3 loading doses then 1000 mg IV weekly with P 5 mg PO BID or P only. Primary endpoint was the proportion of pts progression free (PPF) at 12 weeks (PCWG2 criteria). A 2-stage MinMax design (H0 = 5%, HA >20%, α=0.1, β=0.1) with 32 pts/arm provides 70% power to detect the difference at 0.10 1-sided significance. Secondary endpoints include PSA decline, measurable disease response, and circulating tumour cell (CTC) enumeration. Results: 38 pts have been enrolled; 1st stage of accrual completed with 2nd stage accruing. In the 1st 32 pts randomized (17 to OGX-427+P, 15 to P), baseline median age was 71 years (53-89), ECOG PS 0 or 1 in 66% and 34% of pts, median PSA 66 (6-606), metastases in bone/lymph nodes/liver or lung was 75/56/9%, 31% had prior P treatment, and 93% had ≥5 CTC/7.5 ml. Predominantly grade 1/2 infusion reactions (chills, diarrhea, flushing, nausea, vomiting) occurred in 47% of pts receiving OGX-427+P. One pt on OGX-427+P developed hemolytic uremic syndrome. A PSA decline of ≥50% occurred in 41% of pts on OGX-427+P, and 20% of pts treated with P. A measurable disease partial response was seen in 3/8 (38%) evaluable pts on OGX-427+P and 0/9 pts on P. CTC conversion from ≥5 to <5/7.5 ml occurred in 50% of pts on OGX-427+P and 31% treated with P. Thus far, in 26 evaluable pts the PPF at 12 weeks was 71% (95% CI: 42-92) in OGX-427+P treated pts and 33% (95% CI: 10-65) in pts on P. Conclusions: These data provide clinical evidence for the role of Hsp27 as a therapeutic target in prostate cancer and support continued evaluation of OGX-427 for pts with CRPC. Funded by a grant from the Terry Fox Research Institute.

Correlation of 18F-fluoride PET response to dasatinib in castration-resistant prostate cancer bone metastases with progression-free survival: Preliminary results from ACRIN 6687.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 5003-5003
Author(s):  
Evan Y. Yu ◽  
Fenghai Duan ◽  
Mark Muzi ◽  
Jeremy Gorelick ◽  
Bennett Chin ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Bone Metastases ◽  
Pet Imaging ◽  
Progression Free Survival ◽  
Post Treatment ◽  
Castration Resistant Prostate Cancer ◽  
Free Survival ◽  
Normal Bone ◽  
Castration Resistant ◽  
Pre Treatment

5003 Background: Dasatinib is a SRC kinase inhibitor that decreases bone turnover in men with metastatic castration-resistant prostate cancer (mCRPC). 18F-fluoride PET was used to evaluate differential response between normal and tumor bone to dasatinib. Methods: Patients with bone mCRPC underwent dynamic 18F-flouride PET imaging prior to and 12 weeks after dasatinib treatment. Up to 5 bone metastases with matching normal bone regions were selected for analysis by SUVmax, Ki, K1and Patlak flux. Their pre-treatment values and change from pre-treatment to post-treatment values were evaluated via generalized estimating equations to predict skeletal-related events (SRE) and via Cox proportional hazards modeling to predict progression-free survival (PFS) with Prostate Cancer Working Group 2 criteria, overall survival and time to SRE. Results: Eighteen patients treated with dasatinib underwent baseline 18F-flouride PET imaging; 12 had follow-up scans allowing assessment of changes due to therapy. Median age for all patients was 69 (range 48-86) years. Significant decrease in SUVmax (p=0.0002) occurred in bone metastases with dasatinib while significant increases in Patlak flux (p=0.0033) occurred in normal bone. Significant differences in changes from tumor bone compared to normal bone in response to dasatinib were noted for SUVmax (p<0.0001). Of 18 patients, 17 have either met progression criteria or death by the time of this analysis. Decrease in tumor bone SUVmax (p=0.019), Ki(p=0.022), and Patlak flux (p=0.034) from pre-treatment to post-treatment correlates with longer PFS. Conclusions: 18F-fluoride PET indicates differential effect of dasatinib on tumor compared to normal bone in men with mCRPC. In patients undergoing pre- and post-dasatinib 18F-fluoride PET imaging a decrease in bone mCRPC fluoride uptake in response to treatment correlates with PFS. Clinical trial information: NCT00936975.

Initial results from a phase II study of increased-dose abiraterone acetate in patients with castration resistant prostate cancer (CRPC).

2015 ◽  
Vol 33 (7_suppl) ◽  
pp. 188-188 ◽  
Author(s):  
Terence W. Friedlander ◽  
Julie Nicole Graff ◽  
Li Zhang ◽  
Rosa Paz ◽  
Gayatri Premasekharan ◽  
...  
Keyword(s):  
Radiographic Progression ◽  
Standard Dose ◽  
Neuroendocrine Differentiation ◽  
Genomic Analysis ◽  
Abiraterone Acetate ◽  
Castration Resistant Prostate Cancer ◽  
Dose Therapy ◽  
Pre Treatment ◽  
Grade 3 ◽  
Ecog Ps

188 Background: Resistance to abiraterone is hypothesized to result from increased systemic or tumor androgen production, mutations in the androgen receptor (AR) signaling pathway leading to ligand-independent, autonomous AR activity, and/or AR-independent pathways. This study investigated the clinical benefit of maximization of androgen suppression by increasing the abiraterone acetate dose at the time of initial resistance to standard-dose therapy. Methods: Eligible patients had progressive metastatic CRPC per consensus criteria. No prior abiraterone, enzalutamide, or chemotherapy was allowed. All patients started therapy with abiraterone acetate 1,000 mg daily and prednisone 5mg BID. Patients achieving any PSA decline after 3 cycles continued abiraterone until PSA or radiographic progression. At progression the abiraterone acetate dose was increased to 1,000 mg BID, prednisone was maintained at 5mg BID, and patients were monitored for response for a minimum of 12 weeks or until a second PSA or radiographic progression. Results: 41 patients were accrued from 3/2013 through 3/2014, and 13 patients currently remain on therapy. Median age was 68 (range 55-79), median ECOG PS was 0 (range 0-2), and median baseline PSA was 27.4 (range 3.9-1763). Thirteen men (31%) underwent a pre-treatment metastatic biopsy. To date 13 men who experienced progressive disease on standard-dose therapy were treated with 1,000 mg BID therapy, and are evaluable for response. No PSA declines ≥30% nor radiographic responses have been observed at the elevated-dose. Grade 3 transaminitis was observed in 1 patient on the elevated dose and resolved with dose decrease. Conclusions: Pharmacokinetic failure alone is unlikely to explain resistance to standard-dose abiraterone acetate and increasing the dose at the time of resistance may be of limited clinical utility. Analysis of serial androgen levels, abiraterone pK, and molecular and genomic analysis of circulating tumor cells and metastatic biopsies is underway, with a specific focus on the contributions of AR amplification, AR splice variation, and mesenchymal and neuroendocrine differentiation to the development of abiraterone resistance. Clinical trial information: NCT01637402.

Clinical significance of CTC enumeration on the Epic Sciences platform in metastatic castration-resistant prostate cancer (mCRPC) patients treated with AR signaling inhibitors (ARSi).

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. 5571-5571
Author(s):  
Joseph Schonhoft ◽  
Audrey Gill ◽  
Ryon P Graf ◽  
Adam Jendrisak ◽  
Ethan Barnett ◽  
...  
Keyword(s):  
Intact Cell ◽  
Prognostic Significance ◽  
Circulating Tumor Cell ◽  
Continuous Variable ◽  
Castration Resistant Prostate Cancer ◽  
Risk Of Death ◽  
Signaling Inhibitors ◽  
Pre Treatment ◽  
Prostate Cancers ◽  
Line Of Therapy

5571 Background: Circulating Tumor Cell (CTC) number, enumerated using the analytically valid FDA cleared Cell Search (Menarini Silicon Biosystems) platform has been shown to be prognostic for survival pre- and post-therapy, and used as an aid to monitoring breast, colorectal and prostate cancers. The assay uses antibody-based capture and defines a CTC as an EpCAM+ and CD45- intact cell. In contrast, with the Epic sciences CTC detection platform red blood cells are first lysed and all nucleated cells deposited on pathology slides, fixed, and imaged. There is no affinity selection and CTCs for this analysis were defined in silico as any cytokeratin (CK)+, CD45- cell with an intact DAPI+ nucleus. Here we report the prognostic significance of the CK+ CTCs detected on the EPIC Sciences platform in mCRPC patients prior to treatment with an AR signaling inhibitor. Methods: A pre-treatment blood sample was collected from 181 unique patients with progressing mCRPC about to start an ARSI as 1st, 2nd or 3rd line therapy at MSKCC. CTCs were enumerated on the Epic Sciences platform and verified by a trained human technician. Results: At least 1 CTC was detected (median = 1, 0-711 CTCs/ml) in 134 (74%) of cases, with higher counts observed in patients with visceral or multiple osseous sites relative to those with lymph node only disease. Counts increased by line of therapy. The table shows the associated risk of death for CTCs modeled as a continuous variable. Conclusions: The results support the clinical validity of CTC number determined on the Epic Sciences platform as a significant baseline prognostic factor. In multivariate modeling CTC number was found to be the most significant blood-based predictor of poor OS with each doubling representing a 20% greater risk of death observed with adjustment for therapy line, LDH, PSA, and ALK. [Table: see text]

TALAPRO-1: A phase II study of talazoparib (TALA) in men with DNA damage repair mutations (DDRmut) and metastatic castration-resistant prostate cancer (mCRPC)—First interim analysis (IA).

2020 ◽  
Vol 38 (6_suppl) ◽  
pp. 119-119 ◽  
Author(s):  
Johann S. De Bono ◽  
Niven Mehra ◽  
Celestia S. Higano ◽  
Fred Saad ◽  
Consuelo Buttigliero ◽  
...  
Keyword(s):  
Antitumor Activity ◽  
Primary Endpoint ◽  
Radiographic Progression ◽  
Objective Response ◽  
Specific Antigen ◽  
Progression Free Survival ◽  
Circulating Tumor Cell ◽  
Abiraterone Acetate ◽  
Phase 2 ◽  
Castration Resistant Prostate Cancer

119 Background: Phase 2 and 3 studies with poly(ADP-ribose) polymerase inhibitors (PARPi) have demonstrated antitumor activity in patients (pts) with mCRPC with DDRmut who were previously treated with novel hormonal therapy (NHT). We report the first IA of a Phase 2 study of TALA, a potent inhibitor and trapper of PARP. Methods: TALAPRO-1 (NCT03148795) is enrolling pts (N ≈ 100) with measurable soft tissue disease, progressive mCRPC, and DDRmut likely to sensitize to PARPi (including ATM, ATR, BRCA1, BRCA2, CHEK2, FANCA, MLH1, MRE11A, NBN, PALB2, RAD51C), who received 1–2 chemotherapy regimens (≥1 taxane-based) and progressed on ≥1 NHT (enzalutamide/abiraterone acetate). Pts receive oral TALA 1 mg/d (moderate renal impairment, 0.75 mg/d) until radiographic progression, unacceptable toxicity, or consent withdrawal. Primary endpoint is objective response rate (ORR; blinded independent review). Secondary endpoints are time to OR, duration of response, prostate-specific antigen (PSA) decrease ≥50%, circulating tumor cell (CTC) count conversion (to CTC = 0 and <5 per 7.5 mL of blood), time to PSA progression, radiographic progression-free survival (rPFS), overall survival, safety, pt-reported outcomes, and pharmacokinetics. A planned IA of safety and efficacy was performed after 20 pts with BRCA1/2 mutations were on treatment for ≥8 wks. Results: 81 pts received TALA as of June 5, 2019; 43 pts enrolled by Feb 12, 2019 were evaluable for the primary endpoint (20 BRCA1/2, 2 PALB2, 14 ATM, 7 other). All had received docetaxel and 49% prior cabazitaxel. Overall ORR (95% CI) was 25.6% (13.5–41.2), ORRBRCA1/2 50.0% (27.2–72.8), ORRATM 7.1% (0.2–33.9). Overall median (95% CI) rPFS was 5.6 months (mo) (3.5–8.2), rPFSBRCA1/2 8.2 mo (5.6–NE), rPFSATM 3.5 mo (1.7–8.1). Most common treatment-emergent adverse events (≥20%) were anemia, nausea, asthenia, decreased appetite, constipation, and platelet count decreased. Conclusions: TALA monotherapy demonstrates encouraging antitumor activity in docetaxel-pretreated mCRPC pts, especially those with BRCA1/2mut, and was generally well tolerated. This study was sponsored by Pfizer Inc. Clinical trial information: NCT03148795.

Phase II study of cabazitaxel (CAB) plus enzalutamide (ENZ) in metastatic castration-resistant prostate cancer (mCRPC).

2020 ◽  
Vol 38 (6_suppl) ◽  
pp. 86-86
Author(s):  
Julie Nicole Graff ◽  
Heather H. Cheng ◽  
Jacqueline Vuky ◽  
Joshi J. Alumkal ◽  
Dustin Kreitner ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Phase I ◽  
Phase Ii ◽  
Single Agent ◽  
Failure To Thrive ◽  
Castration Resistant Prostate Cancer ◽  
Eligibility Criteria ◽  
Psa Response ◽  
Pre Treatment ◽  
Grade 3

86 Background: There are six agents that improve survival in mCRPC, each administered as a single agent. Combinations of agents with distinct mechanisms of action have the potential to improve outcomes. Methods: We performed a multi-institution phase I/II study to examine safety and efficacy of CAB plus ENZ with mandatory granulocyte-colony stimulating factor support in mCRPC. Results: A sample size of 3 to 12 subjects for the phase I portion and 33 for the phase II portion provided 82% power to detect PSA response rate (decrease ≥90%) of 50% compared to the null hypothesis of 24%. The main eligibility criteria allowed prior abiraterone/prednisone (AAP) and docetaxel (in the metastatic hormone sensitive setting). Baseline characteristics: median age 69 years (47 - 82), median PSA 20.2 ng/dl (0.2 - 966.3); 7 subjects had visceral disease, 10 received prior AAP, and 8 received prior docetaxel. In the phase I portion, there were no dose limiting toxicities using CAB 25 mg/m2 IV Q3wks up to 10 cycles and ENZ 160 mg PO QD, hence this dosing was used for the phase II portion. 33 men with mCRPC were treated with CAB plus ENZ in the phase II arm. PSA response rates are listed in Table. Prior exposure to AAP decreased PSA response, but subjects who had prior AAP also had higher pre-treatment PSA. There were no treatment related deaths. Dose reduction of CAB to 20 mg/m2 was needed in 7 subjects. Over the course of the study, 14 Grade 3 adverse events occurred that were deemed possibly related to treatment: fatigue (n=2, 6%), febrile neutropenia (n=2, 6%), leukopenia (n=2, 6%), thrombocytopenia (n=2, 6%), anemia (n=1, 3%), hypertension (n=1, 3%), leukocytosis (n=2, 6%), fracture (n=1, 3%), failure to thrive (n=1, 3%). Conclusions: CAB plus ENZ was tolerable and associated with promising anti-tumor activity, particularly in abiraterone-naïve subjects. Further evaluation of this regimen is warranted. This project was managed by the Prostate Cancer Clinical Trials Consortium and funded by Astellas Inc. and Sanofi. Clinical trial information: NCT02522715. [Table: see text]

Phase III study of pembrolizumab (pembro) plus docetaxel and prednisone for enzalutamide (enza)- or abiraterone acetate (abi)–pretreated patients (pts) with metastatic castration-resistant prostate cancer (mCRPC): KEYNOTE-921.

2020 ◽  
Vol 38 (6_suppl) ◽  
pp. TPS262-TPS262 ◽  
Author(s):  
Daniel Peter Petrylak ◽  
Neal D. Shore ◽  
Mostefa Bennamoun ◽  
Raffaele Ratta ◽  
Josep M. Piulats ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Single Agent ◽  
Abiraterone Acetate ◽  
Phase Iii ◽  
Castration Resistant Prostate Cancer ◽  
End Points ◽  
Biomarker Analysis ◽  
Psa Response ◽  
Modified Recist ◽  
Ecog Ps

TPS262 Background: Docetaxel is an established treatment for pts with mCRPC. Pembro, a PD-1 inhibitor, showed single-agent antitumor activity in mCRPC. In the phase 1b/2 KEYNOTE-365 study (NCT02861573), docetaxel + pembro and prednisone showed activity in pts treated with abi or enza for mCRPC, warranting further evaluation. Methods: KEYNOTE-921 (NCT03834506) is a phase 3 trial to evaluate efficacy and safety of pembro + docetaxel and prednisone in chemotherapy-naive pts who progressed with enza or abi therapy for mCRPC. An estimated 1000 pts will be randomly assigned 1:1 to receive docetaxel 75 mg/m2 IV every 3 weeks (Q3W) + prednisone/prednisolone orally 5 mg twice daily (BID) and pembrolizumab 200 mg IV Q3W or docetaxel 75 mg/m2 IV Q3W + prednisone/prednisolone 5 mg orally BID + placebo IV Q3W. Treatment will be stratified by previous next-generation hormone agent (abi or enza) and metastases location (bone only, liver, other). Adults (≥18 years) with histologically or cytologically confirmed mCRPC who progressed with androgen deprivation therapy (or postbilateral orchiectomy) ≤6 months of screening, have ECOG PS 0 or 1, and have adequate organ function are eligible. Pts must have experienced either progression after ≥8 weeks (≥14 weeks for bone progression) or intolerance after ≥4 weeks of abi or enza (but not both) in a chemotherapy-naive mCRPC state. Pts will be required to provide tissue for biomarker analysis. Responses will be assessed by CT or MRI and radionuclide bone imaging per Prostate Cancer Working Group 3 (PCWG3)–modified RECIST v1.1 by blinded independent central review (BICR) Q9W during the first year and Q12W thereafter. Treatment will continue with docetaxel and prednisone for up to 10 cycles and with pembro for up to 35 cycles or until disease progression, unacceptable toxicity, or consent withdrawal. Primary end points are rPFS by BICR and OS. Secondary end points are time to initiation of subsequent anticancer therapy or death, PSA response rate, time to PSA progression, ORR and DOR per PCWG3-modified RECIST v1.1 assessed by BICR, and safety. Accrual began May 2, 2019. Clinical trial information: NCT03834506.

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