New Serum Markers for Prostate Cancer

Abstract Introduction: Pro or precursor forms of prostate-specific antigen (PSA) have emerged as potentially important diagnostic serum markers for prostate cancer detection. Immunoassays were developed to measure specific proPSA forms containing propeptides of 2, 4, and 7 amino acids [(-2)proPSA, (-4)proPSA, and (-7)proPSA, respectively]. Methods: Research-use dual monoclonal antibody immunoassays using europium-labeled detection monoclonal antibodies were developed for each form of proPSA. Sera from patients with prostate cancer or benign prostate disease containing 4–10 μg/L PSA were assayed and analyzed by area under the ROC curve (AUC) for specificity and sensitivity. Results: The proPSA forms had quantification limits of 0.015–0.025 μg/L in serum, with cross-reactivities <1% with PSA. The sum of the proPSA forms divided by free PSA (percentage proPSA) had a higher AUC than did percentage of (-2)proPSA, free PSA, and complexed PSA with AUC (95% confidence intervals) of 0.69 (0.64–0.74), 0.64 (0.58–0.68), 0.63 (0.58–0.68), and 0.57 (0.51–0.62), respectively. The proPSA comprised a median of 33% of the free PSA in cancer and 25% in noncancer sera (P <0.0001). One-third (33%) of cancer samples had >40% proPSA, whereas only 8% of noncancer samples did (P <0.0001). In men with cancer and >25% free PSA, the (-2)proPSA had an AUC of 0.77 (0.66–0.86), with 90% sensitivity and 36% specificity at 0.04 μg/L. Conclusions: The percentage of proPSA gave better cancer detection in the 4–10 μg/L range than did percentage of free PSA and complexed PSA. (-2)proPSA significantly discriminated cancer in men whose serum had >25% free PSA, for whom there is currently no good marker for cancer detection.

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A phase II trial of 17-allylamino-17-demethoxygeldanamycin (17-AAG) in patients with hormone-refractory metastatic prostate cancer

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.15553 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 15553-15553 ◽

Cited By ~ 2

Author(s):

E. I. Heath ◽

D. Hillman ◽

U. Vaishampayan ◽

S. Sheng ◽

F. H. Sarkar ◽

...

Keyword(s):

Prostate Cancer ◽

Cancer Biology ◽

Progression Free Survival ◽

Fold Increase ◽

Median Number ◽

Serum Markers ◽

Primary Objective ◽

Psa Response ◽

Hormone Refractory ◽

Prior Systemic Therapy

15553 Background: 17-Allylamino-17-Demethoxygeldanamycin (17-AAG) is a benzoquinone ansamycin antibiotic with anti- proliferative activity in several mouse xenograft models including prostate cancer models. Serum IL-6, IL-8, and maspin are potentially important markers of prostate cancer biology. Methods: Patients (pts) with metastatic, hormone-refractory prostate cancer progressing on at least one prior systemic therapy with rising PSA were eligible. All pts received 17-AAG at a dose of 300 mg/m2 IV weekly for three out of four weeks. Primary objective was to assess the PSA response (50% decrease in PSA). Secondary objectives included Adverse Events (AEs) and correlative serum markers including IL-6, IL-8 and maspin levels. A Simon two-stage design required a total of 25 pts with early termination if < 2 responses occurred among the 1st 16 eligible patients. Results: Seventeen pts were enrolled of which 15 were deemed eligible. Median age was 68 and median PSA was 252 ng/mL. Pts received 17-AAG for a median number of 2 cycles. No pt had a PSA response. No grade 4/5 AEs occurred. Grade 3 AEs included fatigue (4 pts), lymphopenia (2 pts) and back pain (2 pts). The median PSA progression free survival was 1.8 months (95% CI: 1.3–3.4 months). The six-month overall survival was 61% (95% CI: 37%-100%). Due to the lack of PSA response, accrual was stopped per study design. At day 15, the median IL-6 and IL-8 increase from baseline was 0.4 pg/ml (p=0.57) and 3 pg/ml (p=0.73), respectively. Maspin levels had day 15 increase of 6-fold (p=0.44). At treatment failure (TF), the median IL-6 increase from baseline was 4.47 pg/ml (p=0.03) and IL-8 decrease was 1.8 pg/ml (p=0.31). Maspin levels had a 29-fold increase at TF (p=0.09). Conclusions: 17-AAG did not show any activity with regards to PSA response. Serum IL-6 was significantly increased at the time of TF. Further evaluation of 17-AAG at a dose of 300 mg/m2 IV weekly in this patient population is not warranted. No significant financial relationships to disclose.

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A phase 2 study of prostate specific membrane antigen antibody drug conjugate (PSMA ADC) in patients (pts) with progressive metastatic castration-resistant prostate cancer (mCRPC) following abiraterone and/or enzalutamide (abi/enz).

Journal of Clinical Oncology ◽

10.1200/jco.2015.33.7_suppl.144 ◽

2015 ◽

Vol 33 (7_suppl) ◽

pp. 144-144 ◽

Cited By ~ 10

Author(s):

Daniel Peter Petrylak ◽

Nicholas J. Vogelzang ◽

Gurkamal S. Chatta ◽

Mark T. Fleming ◽

David C. Smith ◽

...

Keyword(s):

Prostate Cancer ◽

Antitumor Activity ◽

Tumor Imaging ◽

Phase 1 ◽

Serum Markers ◽

Electrolyte Imbalance ◽

Phase 2 ◽

Castration Resistant Prostate Cancer ◽

Antibody Drug Conjugate ◽

Phase 2 Trial

144 Background: PSMA is a validated target that is overexpressed selectively on prostate cancer cells. PSMA ADC is a fully human IgG1 antibody conjugated to the microtubule disrupting agent MMAE which binds to PSMA-positive cells, inducing cytotoxicity. A phase 1 study showed activity and tolerability at doses from 1.8-2.5 mg/kg. We have enrolled 119 mCRPC pts who progressed following abi/enz in a phase 2 trial of PSMA ADC. Methods: mCRPC pts (83 taxane experienced (TE) and 36 chemo-naïve (CN)) were administered PSMA ADC 2.5 or 2.3 mg/kg IV Q3 wk for up to 8 cycles. 95% of pts received prior abi and/or enz treatment. Safety, antitumor activity (including PSA, CTCs, and tumor imaging) and exploratory biomarkers were assessed. Results: In all treated pts, PSA declines of ≥30% and ≥50% were 30% and 14%, respectively (n=113); CTC counts showed a decline of ≥50% in 78% of pts and conversion from ≥5 to <5 cells/7.5 ml blood in 47% (n=77) at any time during the study. For 2.3 mg/kg pts (n=82), corresponding PSA declines were 35% and 17%; CTC declines of ≥50% were seen in 81% and conversions in 46% (n=54). For CN pts, PSA declines of ≥30% and ≥50% were 31% and 20% (n=35); CTC declines of ≥50% were seen in 89% and conversion in 53% (n=19). Radiologic response by RECIST in 31 pts with measurable target lesions: PR in 4 pts, SD in 19 pts, and PD in 8 pts. Efficacy responses were associated with: low neuroendocrine serum markers (low CgA, low NSE, and high PSA), high PSMA expression (CTCs or tumor tissue). The most common treatment-related AEs ≥CTCAE grade 3 were neutropenia (TE: 25%; CN: 22%), fatigue (20%; 8%), electrolyte imbalance (16%; 11%), anemia (10%; 8%), and neuropathy (8%; 8%). Grade 1-2 neuropathy occurred in 40% (TE) and 50% (CN) of pts. Two 2.5 mg/kg pts (n=34) and one 2.3 mg/kg pt (n=85) died of sepsis. 2.3 mg/kg was better tolerated than 2.5 mg/kg. Conclusions: PSMA ADC was active in abi/enz refractory mCRPC pts. Clinically significant AEs included neutropenia and neuropathy. CTC conversions/reductions, PSA declines, and radiologic evidence of antitumor activity were seen in CN as well as heavily pretreated pts. Clinical trial information: NCT01695044.

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