Prostate-specific antigen flare phenomenon with docetaxel-based chemotherapy in patients with androgen-independent prostate cancer

OBJECTIVE

To evaluate the prostate‐specific antigen (PSA) ‘flare’ phenomenon in patients with androgen‐independent prostate cancer (AIPC) treated with docetaxel, as flare is a known effect of androgen‐deprivation therapy in hormone‐dependent prostate cancer.

PATIENTS AND METHODS

The charts of 56 patients who received docetaxel‐based chemotherapy in three different centres from August 1999 to August 2007 were reviewed retrospectively. The biochemical response was characterized according to the Bubley criteria. There was an immediate PSA response (PSA decline ≥ 50%) in 23 (41%) patients, PSA stabilization (PSA decline < 50%) in 16 (29%) and PSA progression in nine (16%). There was also a fourth response, i.e. PSA flare, defined as an increase in PSA level with no symptomatic progression, after starting docetaxel‐based chemotherapy administered every 3 weeks.

RESULTS

Eight (14%) patients with PSA flare were identified; all had osseous disease and five had additional soft‐tissue disease. The PSA flare lasted a median (range) of 21 (21–42) days and it spread over a median of 1 (1–2) cycles. The temporary PSA surge exceeded baseline values by a median (range) of 61.5 (12–404)%. There was a subsequent PSA response in six of the eight patients and PSA stabilized in the remaining two. Patients with flare received a median of 8.5 (5–12) treatment cycles, vs a median of 8 (2–12) in the immediate PSA response group (P = 0.103, Student’s t‐test). The Response Evaluation Criteria in Solid Tumors criteria evaluation showed one patient with a partial response and six with stable disease. The median survival of patients with PSA flare was 12.5 months, while that of the immediate PSA responders was 20.1 months (not statistically significant, P = 0.168, log‐rank test).

CONCLUSION

Of patients with AIPC, 14% had an initial PSA flare after starting docetaxel‐based chemotherapy. The occurrence of PSA flare had no effect on treatment duration or outcome. With lack of clinical progression, docetaxel‐based chemotherapy should be administered for at least two 3‐week cycles before further decisions are made about efficacy.     

The combination of docetaxel and the somatostatin analogue lanreotide on androgen-independent docetaxel-resistant prostate cancer: experimental data

OBJECTIVE

To evaluate the effects of the association between docetaxel and the somatostatin analogue lanreotide on the androgen‐independent prostate cancer cell line PC3, either sensitive or made resistant to docetaxel (PC3R), as new drugs and new combinations have promising clinical activity in hormone‐refractory prostate cancer.

MATERIALS AND METHODS

We examined the effect of docetaxel and lanreotide on cell proliferation, with analysis of the mitogen‐activated protein kinase pathway and expression of cell‐cycle regulatory proteins.

RESULTS

Combined treatment with docetaxel and lanreotide inhibited PC3 cell growth in vitro through an enhanced induction of cell death, compared with treatment with either agent alone; this result was particularly evident on PC3R cells. The results suggested that lanreotide could act as a P glycoprotein inhibitor in PC3R cells.

CONCLUSION

The present results provide a promising therapeutic approach for using somatostatin analogues in hormone‐refractory prostate cancer, in which lanreotide could interact with docetaxel in PC3R cells, with possible explanatory mechanisms which involve P glycoprotein‐mediated docetaxel resistance.     

Efficacy of nilutamide as secondary hormonal therapy in androgen-independent prostate cancer

OBJECTIVE: To evaluate the activity of nilutamide as secondary hormonal therapy in patients with androgen-independent prostate cancer (AIPC), as treatment options are limited for these patients and secondary hormonal therapy with antiandrogens has advantages, including low toxicity, oral administration and high patient acceptance. PATIENTS AND METHODS: We retrospectively identified 45 patients with AIPC who were treated with nilutamide as secondary hormonal therapy in two institutions. The decrease in prostate-specific antigen (PSA) levels, side-effects of treatment, and the relationship between baseline characteristics, type and duration of previous therapy and response to nilutamide were assessed. Most patients received oral nilutamide at 150 mg/day. RESULTS: Eighteen of 45 evaluable patients (40%) had a PSA level decrease of > or = 50%. Responders (PSA decline > or = 50%) had a median (range) time to progression of 4.4 (0.31-44.7) months. There were responses to nilutamide whether used as the second to fifth line of hormonal therapy. There were no differences in response to nilutamide based on clinical stage, type of local therapy, PSA level at diagnosis or initiation of nilutamide, or type of previous antiandrogen therapy. Responders were more likely to have received monotherapy with luteinizing hormone-releasing hormone analogues or orchidectomy as first-line hormonal treatment (P = 0.02). The most common reversible adverse effects were mild to moderate visual adaptation effects, reported in 20% of patients. CONCLUSIONS: Nilutamide appears to be an effective secondary hormonal therapy in patients with AIPC and is associated with a mild toxicity profile.     

High dose pulse calcitriol, docetaxel and estramustine for androgen independent prostate cancer: a phase I/II study

PURPOSE: We determined the safety and preliminary efficacy of the combination of high dose pulse calcitriol (1,25-dihydroxycholecalciferol) with a standard regimen of docetaxel plus estramustine in patients with metastatic androgen independent prostate cancer. MATERIALS AND METHODS: Patients were treated with 60 microg calcitriol orally on day 1, 280 mg estramustine orally 3 times daily on days 1 to 5 and 60 mg/m docetaxel on day 2 (70 mg/m after cycle 1) every 21 days for up to 12 cycles. Patients also received 325 mg aspirin and 1 or 2 mg warfarin orally daily. Regimen safety was assessed in the first 6 patients and a dose de-escalation scheme for calcitriol was planned if dose limiting toxicities were noted during treatment cycle 1 in greater than a third of patients. RESULTS: A total of 24 patients, including 11 who were chemotherapy na?ve and 13 who had previously been treated with docetaxel, were evaluable for toxicity and 22 for prostate specific antigen decrease data. The regimen was generally well tolerated. Treatment related grades 3 or greater toxicity seen in more than 1 patient included hypophosphatemia in 16.7% and neutropenia in 12.5%. Four patients had thromboembolic complications. Asymptomatic hypercalcemia was seen in 4 patients, including grades 2 and 1 in 1 and 3, respectively. Six of 11 evaluable, chemotherapy na?ve patients (55%) met prostate specific antigen response criteria. One of 11 patients (9%) treated with prior docetaxel met these criteria. CONCLUSIONS: High dose calcitriol may be safely added to docetaxel and estramustine administered on a 21-day schedule.     

Molecular modelling of the androgen receptor axis: rational basis for androgen receptor intervention in androgen-independent prostate cancer

Androgen depletion in combination with antiandrogenic agents is initially highly effective for treating prostate cancer, and is the recommended treatment for more advanced or higher-grade tumours. However, many tumours eventually become insensitive to androgens, even though the androgen receptor (AR) continues to be expressed. Computational chemistry combined with structural analysis of nuclear receptors and determination of binding affinities of natural and designed coregulators (coactivators and corepressors) provides the theoretical framework for the rational design of novel therapeutic agents directed at the AR. Adding alternative groups to various sites throughout the receptor can alter the conformation of the molecule and its functional binding with coactivators or corepressors. Possible molecules can be identified thoroughly and systematically using intelligent high-throughput screening and FASTrack chemistry (three-dimensional crystallography). Applying these techniques should eventually result in therapeutic agents for androgen-independent prostate cancer that can block binding of AR coactivators while simultaneously increasing binding of AR corepressors.     

A randomized study of docetaxel and dexamethasone with low- or high-dose estramustine for patients with advanced hormone-refractory prostate cancer

OBJECTIVE: To test the combination of docetaxel with two different doses of estramustine in patients with hormone-refractory prostate cancer (HRPC), to improve response rates and to lower side-effects, as docetaxel-based chemotherapy is an increasing option for men with advanced HRPC, and alone or combined with estramustine, docetaxel improves median survival. PATIENTS AND METHODS: In all, 72 patients with metastatic HRPC were randomly assigned to receive docetaxel (70 mg/m(2) intravenously, on day 2 every 21 days) and estramustine (3 x 280 mg/day oral starting 1 day before docetaxel, for 5 consecutive days) for arm A, or estramustine (3 x 140 mg/day oral starting 1 day before docetaxel, for 3 consecutive days) for arm B. Premedication with oral dexamethasone at a total daily dose of 16 mg, in divided doses twice a day was administered in arm A on day 1-5 and in arm B on day 1-3. Initially, six cycles were administered. Chemotherapy was restarted after a significant increase in prostate-specific antigen (PSA) level. Patients were monitored for any measurable PSA response and toxicity. RESULTS: Between the arms there was no statistically significant difference in time to progression and overall survival. However, treatment B had less treatment-related toxicity than A. Independent prognostic variables were baseline factors like PSA level, haemoglobin level, Eastern Cooperative Oncology Group performance status, and bone pain at presentation. CONCLUSIONS: In this randomized phase II study the combination of docetaxel and estramustine had substantial activity in HRPC, with a significant incidence of severe toxicity, both haematological and not. Nevertheless, treatment-related toxicity was predictable and manageable. There was no better effect with a higher dose of estramustine with docetaxel than for a lower dose. There was a slight tendency to higher toxicity for high-dose estramustine but this was not statistically significant. The present results support the assertion that estramustine is not necessary in docetaxel-based treatment regimens.     

Safety and efficacy of docetaxel,estramustine phosphate and hydrocortisone in hormone‐refractory prostate cancer patients

Objective: To assess the combination of docetaxel (DTX), estramustine phosphate (EMP) and hydrocortisone for patients with hormone‐refractory prostate cancer (HRPC). Methods: A total of 63 patients with HRPC were treated with a chemotherapeutic regimen including DTX, EMP, and hydrocortisone. Clinical and pathological features were correlated to serum prostate‐specific antigen (PSA) recurrence and survival rates. Incidence and degree of toxicities were also retrospectively reviewed. Results: A median of 11 courses of chemotherapy was administered per patient. PSA levels decreased by >50% in 32 (51%) patients and >90% in 18 (29%) patients. Median time to PSA progression was 6 months (range from 1 to 41 months) and median time of overall survival was 14 months (range from 1 to 56 months). In a univariate analysis to predict overall survival, PSA, hemoglobin, alkaliphosphatase, and performance status prior to the chemotherapy were significant factors. Despite grade 3–4 neutropenia in 87% of patients, grade 5 interstitial pneumonia in one patient and grade 4–5 myocardial infarction in two patients were recognized, the regimen seemed to be relatively safe. Conclusions: Combination chemotherapy with DTX, EMP and hydrocortisone provides survival benefits for patients with HRPC with an acceptable toxicity profile. We need to further evaluate who might benefit most from this regimen.     

Combination chemotherapy with weekly docetaxel and estramustine for hormone refractory prostate cancer in Japanese patients

Abstract:   The aim is to evaluate the efficacy and toxicity of weekly docetaxel and estramustine for Japanese men with hormone refractory prostate cancer who were treated at a single institution. Twenty eligible patients had histologically proven adenocarcinoma of the prostate with metastases that were progressing despite complete androgen blockade and antiandrogen withdrawal. All of the patients received docetaxel 30 mg/m² weekly (days 1, 8, 15, 22, 29, and 36). After a two week break, the treatment schedule was repeated. Patients were scheduled to receive daily oral estramustine 560 mg/day throughout the protocol. In the serum prostate specific antigen (PSA) response, three (15%) patients achieved a complete response, and 8 (40%) acheived a partial response. Overall survival and time to progression were 13.4 months and 6.4 months, respectively, however sixty-seven percent of the patients had to discontinue treatment because of toxicity. The high toxicity of this protocol suggests that the regimen and/or the timing should be altered for Japanese patients.     

ASCENT: the androgen-independent prostate cancer study of calcitriol enhancing taxotere

ASCENT, the Androgen-Independent Prostate Cancer (AIPC) Study of Calcitriol Enhancing Taxotere, is a double-blind, placebo-controlled randomized clinical trial designed to determine if DN-101, a high-dose oral formulation of calcitriol designed for cancer therapy, significantly increases the proportion of patients who have > 50% reduction in serum prostate-specific antigen (PSA) levels in response to docetaxel. The secondary goals of ASCENT are to evaluate the effect of DN-101 combined with docetaxel on PSA progression-free survival, tumour response rate in measurable disease, tumour progression-free survival, skeletal morbidity-free survival, clinical progression-free survival, and overall survival, and to examine the safety and tolerability of DN-101 combined with docetaxel. ASCENT builds on phase I work showing that weekly dosing allows substantial dose-escalation of calcitriol, the natural ligand for the vitamin D receptor, and on phase II work that suggested that adding weekly high-dose 'pulse' calcitriol may enhance the activity of weekly docetaxel in patients with AIPC. The preclinical rationale for calcitriol and its combination with docetaxel for prostate cancer therapy is reviewed, as are the key clinical trials that led to the development of ASCENT. The ASCENT design and its strengths and limitations are presented.     

PSA nadir and time to PSA nadir during initial androgen deprivation therapy as prognostic factors in metastatic castration-resistance prostate cancer patients treated with docetaxel

Prostate-specific antigen nadir (nPSA) and time to nPSA (TTN) have been proved to be associated with the prognosis of prostate cancer. In this study, we explored the prognosis effect of nPSA and TTN during initial androgen deprivation therapy (ADT) in patients with metastatic castration-resistant prostate cancer (mCRPC) after treatment with docetaxel-based chemotherapy. The data of 153 mCRPC patients received docetaxel followed by ADT were retrospectively reviewed. Multivariate Cox regression analysis demonstrated that TTN (overall survival (OS): Hazard ratio [HR] 0.096, 95% confidence interval [CI] 0.045–0.206, p < .001; progression-free survival (PFS): HR 0.128, 95% CI 0.078–0.211, p < .001) and nPSA (OS: HR 2.849, 95% CI 1.318–6.157, p = .008; PFS: HR 1.573, 95% CI 1.008–2.454, p = .046) acted as independent predictors of chemotherapy prognosis. Kaplan-Meier analysis showed that patients with nPSA ≥ 0.2 ng/ml or TTN < 6.5 months had shorter OS and PFS. These results suggest that TTN and nPSA during ADT can affect the prognosis of docetaxel-based chemotherapy prognosis post-castration resistance in patients with mCRPC, and higher nPSA and shorter TTN lead to poor chemotherapy prognosis. What is more, TTN has a greater impact during ADT on the prognosis of chemotherapy than nPSA.     

Establishment and characterization of androgen-independent human prostate cancer LNCaP cell model

BACKGROUND: The acquisition of an androgen-independent phenotype is the most serious issue of prostate cancer treatment. Although several experimental cell models have been reported for studying androgen independence, they have limited applications related to hormone-refractory prostate cancer. To investigate the molecular mechanism of androgen-independent growth of prostate cancer, we established a useful LNCaP cell model that resembles the clinical scenario of hormone-refractory prostate cancer. METHODS: Androgen-sensitive LNCaP parental cells were continuously maintained in a regular cell-culture medium, that is, phenol red-positive RPMI 1640 medium supplemented with 5% fetal bovine serum and 1% glutamine. Upon passage, the androgen responsiveness of those cells decreased, to a level lower than that of parental cells. We examined the growth properties and androgen responsiveness of these different LNCaP cells in vitro and in vivo. Cytogenetic characteristics and expression of androgen receptors (ARs) and prostate-specific antigen (PSA) were determined. RESULTS: Upon continuous passage, the biological behavior of parental C-33 cells (passage number less than 33) was altered. C-81 cells (passage number higher than 81) clearly exhibited more aggressive growth and lower androgen responsiveness than C-33 and C-51 cells (passage number between 35 and 80) in vitro and in vivo. Nevertheless, all these cells expressed a similar level of functional AR protein as well as a similar genetic profile. Moreover, in a steroid-reduced culture condition, C-81 cells secreted a higher level of PSA than C-33 cells. CONCLUSIONS: Our LNCaP cell model closely recapitulates the progression of human prostate cancer from the androgen-responsive to the hormone-refractory state under the androgen nondeprived condition. This cell model may provide the opportunity to understand the molecular mechanisms associated with the acquisition of androgen independence during human prostate cancer progression.     

A phase II study of high-dose calcitriol combined with mitoxantrone and prednisone for androgen-independent prostate cancer

OBJECTIVE

To evaluate the preliminary efficacy, safety, and impact on quality of life (QoL) of high‐dose calcitriol (DN‐101) combined with mitoxantrone and glucocorticoids in androgen‐independent prostate cancer (AIPC).

PATIENTS AND METHODS

Nineteen patients with metastatic AIPC and no previous chemotherapy received DN‐101 180 µg orally on day 1 and mitoxantrone 12 mg/m² intravenously on day 2 every 21 days with continuous daily prednisone 10 mg orally for a maximum of 12 cycles. A confirmed decline in prostate‐specific antigen (PSA) levels by half was the primary endpoint. QoL was evaluated using the European Organization for Research and Treatment of Cancer QLQ‐C30 questionnaire, and pain and analgesic use were evaluated.

RESULTS

Five of 19 patients (26%; 95% confidence interval, CI, 9–51) achieved a ≥50% decline in PSA level. The median (95% CI) time to PSA progression was 16 (6–26) weeks. The overall median (95% CI) survival was 16 (6–26) months; 47 (21–73)% of patients achieved an analgesic response. Toxicity was similar to that expected with mitoxantrone and prednisone alone. The QoL analysis suggested a decrease in physical functioning and increase in fatigue, insomnia, and diarrhoea.

CONCLUSIONS

DN‐101 given every 3 weeks does not add significant activity to mitoxantrone and prednisone in AIPC, as measured by the PSA decline. The high rate of analgesic response is encouraging. The addition of DN‐101 does not appear to increase the toxicity of mitoxantrone.     

Differential regulation of IGFBP-3 by the androgen receptor in the lineage-related androgen-dependent LNCaP and androgen-independent C4-2 prostate cancer models

BACKGROUND: Despite evidence implicating insulin-like growth factor binding protein-3 (IGFBP-3) as a growth inhibitor of prostate cancer (CaP), little is known about changes in its regulation and function during progression to androgen independence. METHODS: The expression levels of IGFBP-3 were determined by cDNA microarray analysis and tissue microarrays (TMAs) after androgen ablations. LNCaP (LN-BP3) and C4-2 (C4-2-BP3) sublines were used to compare the apoptotic effects of IGFBP-3 in LNCaP (androgen-dependent) and C4-2 (androgen-independent) cells. RESULTS: After androgen deprivation, IGFBP-3 mRNA levels increased more in C4-2 compared to LNCaP cells. Androgens suppressed IGFBP-3 levels in a dose-dependent manner in LNCaP and C4-2 cell. IGFBP-3 expression was increased after NHT in human CaP tissues. Apoptotic rates increased in LN-BP3, but not C4-2-BP3 cells, following doxycycline-mediated IGFBP-3 induction. CONCLUSIONS: C4-2 cell survival in an androgen-depleted environment may be facilitated through differential resistance to the apoptotic effects elicited by IGFBP-3.