Final results of a phase I study of oral belinostat (PXD101) in patients with solid tumors

3531

Background: Belinostat (Bel) is a histone deacetylase inhibitor with broad preclinical activity. IV Bel is well-tolerated with clinical activity at 1 g/m2 daily x5, q3w. Methods: Patients (pts) were treated with multiple schedules (see table) to assess safety, pharmacokinetics (PK) and efficacy. PK was done on day (d) 1 (fasting) and d7 (non-fasting) along with serial ECGs. Results: 92 pts, median age 60 (range 32–89) have been included. Major cancer types included colorectal (22%), prostate (17%), bladder (11%). Most frequent related adverse events (AEs), any grade (gr), were fatigue (53%), nausea (49%), anorexia (36%), vomiting (27%), diarrhea (25%). Only related gr 3/4 AE noted by more than 1 pt was fatigue. Hematological tox included gr 2: anemia (6 pts), leucopenia (2 pts), and thrombocytopenia (1 pt). Two events of gr 2 QTc prolongation were reported. Recommended dose (RD) for continuous dosing was determined as 250 mg, QD or BID, based on dose limiting toxicity (DLT; gr 3 if not indicated) seen in 2 pts in cohort 2A: dehydration and fatigue. Based on overall tolerability and DLTs (cohort 2C fatigue; 3C gr 2 nausea/vomiting/diarrhea; 4C atypical chest pain, elevated creatinine; 2D atrial fibrillation, hypokalemia, fatigue) the RD for d1–14 dosing was determined as 750 mg QD, with option for intra-pt dose escalation if limited tox. For d1–5 dosing, evaluation of the highest dose-cohort is not finalized; 1 pt had gr 3 psychosis, but also experienced same event 16d after treatment stopped. Exposure of Bel in plasma correlates with dose; PK on d1/d7 indicate a possible effect of food. To date, 33 pts (41%) have SD; 5 pts ≥6 months (d on treatment: 710 adenoidcystic, +488 bladder, 485 renal, 196 rectal, 182 prostate), and 12 pts 3–6 months. Conclusions: Oral Bel can be delivered safely with multiple schedules. The safety profile and long stabilizations in multiple tumor types makes Bel an interesting option for further evaluation as a monotherapy and in combination with chemotherapy.

[Table: see text]

[Table: see text]

A combined phase I/II trial of intravesical nanoparticle albumin-bound paclitaxel in the treatment of refractory non–muscle- invasive transitional cell bladder cancer

e16047

Background: Up to 50% of patients treated with intravesical agents for non-muscle-invasive bladder cancer will recur. Response rates to current second line intravesical therapies average less than 20%. For these high risk patients, novel agents are necessary. Our previously completed phase I trial showed docetaxel to be a safe and efficacious agent for intravesical therapy. Nanoparticle albumin-bound (nab-) paclitaxel has been shown to have increased solubility and lower toxicity compared to docetaxel in systemic therapy and is therefore an appropriate candidate for further investigation as an intravesical agent. Methods: The ongoing phase I component of this combined phase I/II trial began enrollment on 1/1/08 and has reached 72% accrual as of 1/1/09. Inclusion criteria include recurrent high grade (HG) Ta, T1 and Tis transitional cell carcinoma failing at least one prior regimen with any intravesical agent. In phase I, 6 weekly instillations of nab-paclitaxel were administered beginning at a dose of 150 mg with a dose escalation model used until a maximal tolerated dose (MTD) was achieved. The primary endpoints were dose- limiting toxicity (DLT) and MTD; the secondary endpoint was response rate. Efficacy was evaluated by cystoscopy with biopsy, cytology, and CT imaging. Results: 13/18 patients have enrolled in this phase I trial to date, and the distribution of stages included 5 patients with Tis, 4 patients with HGTa, and 4 patients with HGT1. No patient has had any systemic absorption of nab-paclitaxel as measured by HPLC assays, and no grade 3 or 4 DLT has been encountered. Fifty-four percent (7/13) patients were noted to experience grade 1 toxicities, with dysuria being the most common. Forty-two percent (5/12) of completed patients had no evidence of disease at their post-treatment cystoscopy. None of the patients who developed recurrent disease have had disease progression. Conclusions: Intravesical nab-paclitaxel has exhibited minimal toxicity and no systemic absorption in the first ever human intravesical dose escalation trial. Upon completion of this ongoing phase I trial, we plan to evaluate this agent in a larger phase II efficacy study.

No significant financial relationships to disclose.

Final results of a phase I study of oral belinostat (PXD101) in patients with lymphoma

8580

Background: Belinostat (Bel) is a histone deacetylase inhibitor with broad preclinical activity. A phase I of oral Bel in patients (pts) with solid tumors found a recommended dose for day (d) 1–14, q3w, of 750 mg QD, with option for intra-patient dose escalation if limited toxicity. The current study was initiated to assess if the same dose could be utilized in pts with lymphoma. Methods: Objectives included safety and efficacy of oral Bel in cohorts of 3–6 pts (A 750; B 1000; C 1250; mg QD) treated d 1–14, q3w. Pts with relapsed/refractory non-Hodgkin lymphoma (NHL) or Hodgkin's disease (HD) with evaluable disease and acceptable organ functions were eligible. Dose limiting toxicity (DLT) assessed in cycle 1 included: related non-hem grade (gr) 3/4 tox; gr 4 neutropenia > 5 d or with fever > 100.5 °F; gr 4 thrombocytopenia > 7 d. Results: 9 pts (3 per cohort), median age 51 (range 21–92), median 5 (range 2–7) prior regimens (83% had BM transplants, including 1 pt with allogeneic) have been enrolled. Diagnoses include mantle cell lymphoma (MCL; 4 pts), HD (3 pts), other NHL (2 pts). Most frequent adverse events (regardless of attribution or gr) in 7 pts fully evaluable for tox: anorexia (7 pts), fatigue, (6 pts), diarrhea (6 pts), and constipation, fever, and cough (each in 3 pts). Non-hem gr 3 events (no gr 4 noted): diarrhea (1 pt each in cohorts A and B, both in cycle 2), fatigue, anorexia, and leg DVT (each in 1 pt; all after cycle 1). One gr 3, and 1 gr 4 (from baseline gr 2; duration gr 4 <7 d) thrombocytopenia were seen in cohort C. In 6 pts evaluable for efficacy, stable disease have been noted in 5 pts for 3 to +7 cycles, including 3 of 3 pts (one refractory) with MCL and 2 of 2 pts (both refractory) with HD. Tumor shrinkage of 43 to 49% have been found in 1 HD and 2 MCL pts after cycle 2. Conclusions: Oral Bel can be delivered safely with a d 1–14, q3w schedule in pts with lymphoma at a daily dose higher than what has been established for pts with solid tumors. No protocol defined DLTs have yet been encountered in the dose range 750 to 1250 mg QD in pts with lymphoma. Final evaluation will include additional pts and possible dose escalation. The safety profile and early tumor shrinkage noted in MCL and HD warrants continued evaluation of Bel, especially in combination with other active compounds.

[Table: see text]

Use of pain at baseline and pain progression to predict overall survival (OS) in patients (pts) with docetaxel pretreated metastatic castration-refractory prostate cancer (CRPC): Results from the SPARC trial

5148

Background: First-line chemotherapy trials have reported that pain predicts OS in CRPC. We report relationships between OS and baseline pain –a major component of CRPC patient reported outcomes (PRO) –and pain at progression, for docetaxel pre-treated patients in a second-line chemotherapy trial in CRPC. Methods: Docetaxel pre-treated pts (N = 488) were analyzed from the multi-national, randomized, double-blind SPARC trial, comparing second-line satraplatin + prednisone vs placebo + prednisone in 950 metastatic CRPC pts. Daily pain intensity and narcotic analgesic use were recorded as a PRO from one week prior to randomization until end-of-study. Pain was measured by the 6-point Present Pain Intensity (PPI) component of the McGill-Melzack Pain Questionnaire. After randomization, weekly PPI scores were calculated as the mean of the daily PPI scores (using ≥3 daily measurements/week). Baseline pain was the mean of ≥5 daily PPI scores recorded during 7 days preceding randomization. An independent blinded review committee (IRC) determined pain progression (defined as an increase in weekly PPI score ≥1 point from baseline or ≥2 points from nadir, or a >25% increase from baseline in weekly average analgesic score for ≥2 consecutive weeks). To examine the effects of pain on OS, pts were categorized as “no pain” (PPI ≤1) or pain (PPI ≥2) by baseline assessment; and, as either pain progressors or pain non-progressors. Results: Shortened OS was observed in pts with baseline pain; median survival of 178 pts with pain was 44 weeks vs 72 weeks for 287 pts without pain (Strat. Log-rank p < 0.0001, Strat. HR 0.59; 95% CI: 0.48–0.74). IRC found disease progression in 414 (84.4%) of the docetaxel pre-treated pts with 196 of these pts showing pain progression. Pain progression was strongly linked to OS with 196 pain progressors having median OS of 47 weeks compared to 71 weeks for 292 pain non-progressors (Strat. Log-Rank p = 0.0022; Strat. HR 0.71; 95% CI: 0.57–0.87). Conclusions: Both pain at baseline and pain at progression are important prognostic indicators of OS in metastatic CRPC pts failing first-line docetaxel.

[Table: see text]

Correlation of progression-free survival (PFS) and overall survival (OS) in men with metastatic castration-resistant prostate cancer (CRPC) who failed first-line chemotherapy: Results from the SPARC Trial

5150

Background: It has been shown in chemotherapy naïve patients that PFS is a statistically significant predictor of OS. The main objectives of this analysis were to explore whether PFS at 3-months is a predictor of OS and to investigate the dependence between PFS and OS in CRPC men who failed first line chemotherapy. Methods: Data from SPARC, a multi-national, randomized, double-blind trial, comparing satraplatin + prednisone vs placebo + prednisone in 950 CRPC patients were used. For the purpose of this analysis, the two treatment groups were combined. PFS was defined as the time from date of randomization to date of first progression (bone scan progression, radiographic, soft-tissue progression, symptomatic, or skeletal related events) or death, whichever occurred first. PFS at 3-months was defined as a binary variable in the following manner: if a patient experienced any type of progression at or before 3-months then this was considered as an event. If a patient did not progress at 3 months then he was censored. Landmark analysis of PFS at 3-months predicting OS was performed. In addition, the proportional hazards model was used to assess the significance effect of PFS at 3-months in predicting OS adjusting for the stratification factors. Finally, the association between OS and PFS was investigated using a statistic that estimates Kendall's tau measure of association for bivariate time to event outcomes subject to censoring. Results: 477 (56%) men progressed at 3-months of 853 men who were alive at 3-months. The median survival times were 34.5 weeks (95% CI = 30.8–40.4) and 78.7 weeks (95% CI=70.1–83.2, p-value<0.001) respectively in men who did and did not experience progression at 3-months. Men who had progressed at 3-months were more likely to die than men who did not progress (hazard ratio = 2.16, 95% CI =1.84 -2.55, p-value < 0.001). The dependence between PFS and OS was 0.29 (95% confidence limits = 0.24–0.33, p-value < 0.00001). Conclusions: PFS at 3-months predicts OS. The results of this large retrospective analysis show moderate, but strong statistical dependence between PFS and OS. Future studies are needed to assess the clinical relevance of the distinct components of progression.

[Table: see text]

Phase II study of single-agent vinflunine in platinum-refractory transitional cell carcinoma of the urothelium (TCCU)

15543

Background: Vinflunine (VFL) is a new microtubule inhibitor of the vinca alkaloid class with clinical activity in TCCU (S. Culine, BJC 2006). This trial was conducted to define VFL activity in platinum-refractory TCCU patients (pts). Methods: Multicenter, single-arm study. Primary endpoint: Objective response rate (Independent Review; WHO criteria). Planned sample size: 150 pts. Main pt eligibility: at least one measurable lesion; documented progression within 12 months of last dose of platinum-containing regimen; calculated creatinine clearance (Cr Cl) = 20 mL/min. VFL 320 mg/m2 IV infusion over 20 minutes was administered every 3 weeks. In pts with poor performance status, prior pelvic irradiation, or renal impairment (Cr Cl 20–60 mL/min), initial dose (ID) was 280 mg/m2, escalated to 320 mg/m2 if well tolerated. Results: Enrollment of 150 pts complete. Baseline pt characteristics (first 118 pts treated): Gender: male 78%, female 22%. Median age: 66 years (range 40–83). Renal impairment: 32%. Prior chemotherapy: cisplatin: 69%; carboplatin: 47%, gemcitabine: 94%. Total of 402 VFL cycles administered (range: 1–12). 320 mg/m2 ID: 35 pts; 280 mg/m2 ID: 83 pts. Main toxicity was hematologic (Grade (G) 3/4): neutropenia: 19%/37%; thrombocytopenia: 3%/0%; anemia: 13%/0%; febrile neutropenia: 320 mg/m2 ID: 5 pts; 280 mg/m2 ID: 3 pts. Main non-hematologic toxicities: constipation: 320 mg/m2 ID: 63% (G3/4: 14%/3%); 280 mg/m2 ID: 59% (G3/4: 12%/1%); fatigue: 320 mg/m2 ID: 43% (G3/4: 6%/0%); 280 mg/m2 ID: 35% (G3/4: 7%/0%). Severe diarrhea or vomiting was infrequent. No G3/4 peripheral neuropathy was noted. Responses have been observed by the investigators, but independent review is on-going. Conclusions: VFL has a manageable toxicity profile in pts with platinum-refractory TCCU. Independently reviewed response rate and other efficacy endpoints of the entire cohort will be presented.

No significant financial relationships to disclose.

Satraplatin (S) demonstrates significant clinical benefits for the treatment of patients with HRPC: Results of a randomized phase III trial

5019

Background: Chemotherapeutic options for HRPC are limited. S is a novel oral platinum compound. Methods: The SPARC trial is a multinational randomized double blind study comparing S 80 mg/m2/day x 5 q5weeks po + prednisone (P) vs placebo + P in HRPC patients (pts) who failed prior chemotherapy. In this analysis, progression-free survival (PFS) was the primary endpoint, defined as a composite endpoint of radiologic progression, symptomatic progression, skeletal events or death. All cases were blindly adjudicated for progression by an independent review committee (IRC). Results: 950 pts were accrued between Sept 2004 and Jan 2006. Baseline characteristics were well balanced between treatment arms. 51% of the pts had received prior docetaxel. 68% were ≥ 65 yrs old and 27% were ≥ 75 yrs old. Pts received a median of 4 courses in the S arm (range:1–28) vs 2 courses in the placebo arm (range 1–16). 802 pts had an IRC defined progression-free (PFS) event consisting in 80% of the cases of radiologic progression, pain progression or death. All analyses were conducted on an intent-to-treat basis. S was associated with a 31% reduction in the risk of PFS events (HR=0.69; 95% CI: 0.60–0.80; p<0.00001) and a 33% reduction in the risk of pain progression (HR=0.67; 95% CI: 0.54 - 0.83; p=0.00028). Consistent results in favor of S were found for PFS and time to pain progression in all subsets examined, including pts treated with prior docetaxel. Superior PSA response (25% vs.12%, p=0.00007), objective tumor response (7% vs. 1%, p<0.002), pain response (24% vs. 14%, p<0.005), and duration of pain response (HR=0.59; 95%CI: 0.35–1.00; p=0.049) were observed for S. Final analysis of overall survival awaits the occurrence of the pre-specified number of events. S was generally well tolerated - myelosuppression was the most frequent side effect, but grade 4 neutropenia was uncommon (4%) and a single patient had grade 4 thrombocytopenia. Grade 3/4 non-hematologic side effects included infection (4%), vomiting (2%) and diarrhea (2%). Conclusions: S is well tolerated and significantly reduces the risk of disease progression for HRPC pts who have failed prior chemotherapy. Supported by GPC Biotech and Pharmion

No significant financial relationships to disclose.

Neoadjuvant paclitaxel (P), carboplatin (Ca) and gemcitabine (G) in patients with locally advanced transitional cell carcinoma (TCC) of the bladder: A final report

4541

Background: PCaG has activity in the treatment of TCC. Studies have shown that neoadjuvant chemotherapy may improve survival in TCC, with pathologic complete responders (pT0) having the most benefit. This study was designed to assess the pT0 rate and resectability following neoadjuvant PCaG in patients with TCC of the bladder. Methods: Patients with adequate organ function, performance status 0–2, and clinical T3 or T2 with hydronephrosis, N0, M0 TCC (Arm I) received 3 cycles of PCaG (P: 200 mg/m2, IV over 3 hours day 1, C: target AUC=5 IV day 1, and G: 800 mg/m2; IV day 1 & 8 every 21 days) followed by cystectomy with a primary endpoint of pT0. T4 or node positive (Tany, N1–3, M0) patients (Arm II) received 6 cycles with an endpoint of resectability. Each arm had a Minimax two-stage accrual with planned initial enrollment of 26 evaluable subjects in arm I (up to 54 total) and 19 in arm II (up to 33). Results: 68 patients were registered (31 arm I, 37 arm II). Median age was 65 years in arm I and 58 years in arm II. 22/31 (71%) patients in arm I are evaluable and 7 were pT0 at cystectomy. pT0 rate is 32% (95% CI: 13.9–54.9%) of evaluable, 23% (9.6–41.1%) by intent to treat (ITT). 30/37 (81%) on arm II are evaluable for response and 20 had cystectomy for a resection rate of 67% (47.2–82.7%) of evaluable, 54% (36.9–70.5%) by ITT. 5 patients resected on arm II had pT0 and 2 had only residual carcinoma in situ. A total of 252 cycles of therapy were delivered (80 in arm I, 172 in arm II) with 161 at full dose. 54/68 patients (79%) had grade 3/4 hematologic toxicity, primarily neutropenia with 4 other episodes of grade 3 toxicity (2-neuropathy, 1-myalgia, 1-fatigue). 4 patients died during chemotherapy (2-bowel obstruction, 1-coronary artery disease, 1-intracranial bleed) and 2 post-op (1-multiorgan failure, 1-enterocolitis). Only 1 death was clearly chemotherapy related, but the study was halted early due to these deaths. Conclusions: Neoadjuvant PCaG has demonstrated activity in locally advanced TCC of the bladder, but has considerable toxicity. The pT0 rate with this combination is comparable to the rates reported in the literature for other regimens. Support from Bristol-Myers Squibb, Eli Lilly, and 2P30 CA 46592–14 from the National Cancer Institute

[Table: see text]

Cure of undifferentiated small cell carcinoma of the urinary bladder with M-VAC chemotherapy

Small cell carcinoma (SCC) of the urinary bladder is a rare, aggressive malignancy with approximately 135 cases reported in the literature. Treatments have included chemotherapy, radical surgery, radiotherapy, and combinations of these. We present the apparent cure of a 73-year-old man who presented with clinical stage T2 SCC of the urinary bladder. He was treated with three cycles of methotrexate, vinblastine, Adriamycin (doxorubicin), and cisplatin (M-VAC) chemotherapy. Subsequent radical cystoprostatectomy revealed no pathologic evidence of tumor. The patient is alive and well with no evidence of recurrence 3 years post cystectomy. A brief review of the literature is also presented.

A phase II pilot study of KW-2189 in patients with advanced renal cell carcinoma

BACKGROUND

KW-2189 is a semi-synthetic, water-soluble analog of duocarmycin B2, a new class of potent antitumor antibiotics produced by streptomyces, with improved in vitro antitumor potency.

PATIENTS AND METHODS

Forty patients with pathologically confirmed metastatic renal cell carcinoma were treated in this multicenter, open-label phase II trial. All patients received 0.4 mg/m2 KW-2189 as an i.v. infusion for Cycle I. Cycles were repeated every 5 to 6 weeks with escalations to 0.5 mg/m2 in the absence of significant toxicity or disease progression.

RESULTS

No patient had an objective response. The most common drug-related toxicity was hematological-delayed neutropenia and thrombocytopenia, with recovery by week 6. Non-hematologic toxicity consisted of mild to moderate fatigue, nausea and vomiting, and anorexia that was generally manageable.

CONCLUSIONS

KW-2189 in this dose and schedule has a predictable safety profile of reversible myelosuppression. No activity in metastatic renal cell carcinoma was demonstrated.

Docetaxel (Taxotere) and estramustine versus mitoxantrone and prednisone for hormone-refractory prostate cancer: scientific basis and design of Southwest Oncology Group Study 9916

Hormone-refractory prostate cancer is the terminal step in the natural history of prostate cancer. To date, no chemotherapeutic agents have been shown to impact clinical outcome at this stage. Recently, the Food and Drug Administration approved the combination of mitoxantrone and prednisone based solely on its superior palliative effects as compared to steroids alone in 2 randomized trials. Progress in biologically driven drug development has led to the identification of several estramustine-based regimens that, although based on single institution experience, appear to have at least a comparable but very promising level of activity in hormone-refractory prostate cancer patients. One such combination, estramustine plus docetaxel (Taxotere; Rhône-Poulenc Rorer, Collegeville, PA), is particularly attractive because of its convenient schedule and side effect profile. To objectively assess the therapeutic benefit of this combination, the Southwest Oncology Group is initiating a randomized phase III trial comparing estramustine and docetaxel with the standard arm of mitoxantrone and prednisone using time to progression and survival as the primary end points. Secondary end points will include toxicity profiles, assessments of quality of life parameters, and magnitude of decline of prostate-specific antigen levels between the two treatment arms.

Upregulation of prostate-specific membrane antigen after androgen-deprivation therapy

OBJECTIVES

To determine the expression of prostate-specific membrane antigen (PSMA) before and after androgen-deprivation therapy and to compare PSMA expression with prostate-specific antigen (PSA) expression.

METHODS

We studied specimens from 20 patients with prostate cancer undergoing medical or surgical castration or combination androgen-deprivation therapy in whom matched pretreatment and post-treatment tissue specimens were available and 16 patients in whom only a post-treatment specimen was available. The expression of PSMA and PSA in the tissue specimens was determined by immunoperoxidase staining. The extent of staining was calculated by multiplying the percent of antigen-positive tumor cells by the staining intensity to arrive at a stain index for each biomarker. An in vitro study assessed the concentration of PSMA and PSA in extracts of LNCaP cells cultured in the presence or absence of androgen as determined by immunoassays and Western blot analysis.

RESULTS

PSMA reactivity was found to be increased in 55% (11 of 20) of post-treatment primary tissues and 100% (4 of 4) of post-treatment metastatic specimens. In contrast, PSA expression was found to be decreased in 70% (14 of 20) of post-treatment primary and 100% (4 of 4) of post-treatment metastatic specimens. Neither type of androgen-deprivation treatment nor tissue sensitivity to androgen deprivation appeared to influence degree of biomarker expression. PSMA was found to be downregulated and PSA upregulated when LNCaP cells were cultured in the presence of testosterone or dihydrotestosterone.

CONCLUSIONS

The enhanced expression of PSMA in tissues and LNCaP cells after androgen deprivation suggests that PSMA is upregulated in the majority of prostate carcinomas after androgen treatment. The high expression in metastatic tissues strongly suggests that PSMA may be a clinically useful target for antibody-and genetic-directed therapy of prostate cancer that recurs after androgen deprivation. The mechanism whereby androgens suppress the expression of PSMA, and the association of PSMA with the development of hormone-independent prostate cancers, will require further study.

Changing pattern of expression of the epidermal growth factor receptor and transforming growth factor alpha in the progression of prostatic neoplasms

The autocrine/paracrine interaction of the epidermal growth factor receptor (EGFr) and transforming growth factor alpha (TGF-alpha) has been implicated in prostate cancer cell growth and proliferation. To evaluate the role of EGFr and TGF-alpha in prostate cancer progression, we studied the immunohistochemical staining pattern of EGFr and TGF-alpha in malignant primary and hormone-independent metastatic prostate lesions. The specimens evaluated included 37 primary carcinomas (34 hormone-naive and 3 hormone-refractory tumors) and 22 metastases. For each specimen, the pattern of expression was evaluated and staining reactivities graded from 0-3, with 0 representing no staining and 3 representing homogeneous and intense staining. Primary malignant prostate epithelial cells in areas with discrete gland formation showed strong EGFr immunostaining, while stromal cells were generally nonreactive. In untreated primary tumors, TGF-alpha expression was primarily in the stroma, while epithelial cells were weakly positive in several cases. Malignant epithelial cells adjacent to neural elements that stained positive for TGF-alpha was frequently observed. A homogeneous staining pattern for EGFr was noted in 17 (89%) of 19 evaluable androgen-independent-refractory metastases, while TGF-alpha expression was found in 14 (78%) of 18 evaluable cases. Overall, 14 of 18 androgen-independent metastases coexpressed the receptor and the ligand. These results suggest that, unlike primary prostate tumors where a paracrine relationship between EGFr and TGF-alpha appears to predominate, the potential for autocrine stimulation may exist in the majority of metastatic androgen-independent tumors. Furthermore, the changing pattern of expression as the disease evolves from the localized hormone-naive to metastatic androgen-independent condition suggests that strategies aimed at blocking this growth factor pathway may be of therapeutic importance for androgen-independent disease.

Preclinical studies of gossypol in prostate carcinoma

Hormone refractory prostate cancer remains an incurable disease and the discovery of newer agents with higher cytotoxic activity is required. Gossypol is a phenolic compound isolated from cottonseed oil which has been shown to have anti-spermatogenic effects. In in vitro studies, gossypol appears to inhibit the growth of rat prostate cancer cell line MAT-LyLu and human prostate adenocarcinoma cell lines PC-3, LNCaP and DU-145. In vive, gossypol appeared to inhibit tumor growth of subcutaneously implanted MAT-LyLu cells in Copenhagen rats. Gossypol may be an active agent for the treatment of hormone refractory metastatic prostate cancer.

Effects of suramin-related and other clinically therapeutic polyanions on protein kinase C activity

The mechanism of the antineoplastic effects of suramin may involve interference with signal transduction, but in general is not well understood. We examined several polyanions to determine their effects on the kinase activity of the protein kinase C (PKC) beta1 and other PKC isoforms. Similar to suramin, a phosphorothioate oligodeoxynucleotide 28-mer homopolymer of cytidine (SdC28) inhibited the phosphatidylserine and Ca2+-dependent phosphorylation of an epidermal growth factor receptor octapeptide substrate. The inhibition by suramin was mixed competitive/noncompetitive with respect to ATP, but uncompetitive with respect to substrate. In contrast, the inhibition by SdC28 was competitive with respect to substrate (Ki = 5.4 microM) and not competitive with respect to ATP. The PKC alpha and beta1 isoforms were inhibited to the same extent with SdC28, while PKC epsilon was not inhibited. SdC28, in the absence of lipid cofactor, stimulated substrate phosphorylation, and in the absence of substrate induced PKC beta1 autophosphorylation. Similar behavior was seen with another polyanion, the polysulfated carbohydrate pentosan polysulfate (polyxylyl hydrogen sulfate). H4, a bis-naphthalene disulfonate tetraanion structurally related to suramin, also inhibited kinase activity but was not competitive with respect to ATP. Dianions closely related to H4 failed to inhibit PKC beta1, suggesting that multiple (>2) negative charges are required. The interactions of polyanions with PKC are complex, and are dependent on the molecular structure of the polyanion, the presence of cofactors, and the PKC isoform.

Cytotoxic chemotherapy for advanced renal cell carcinoma

This article reviews 72 cytotoxic chemotherapeutic agents used singly or in a limited number of two drug combinations. Results in 3502 adequately treated patients show objective response (complete and partial remissions) in only 197 or 5.6% (95% CI, 4.8% to 6.4%). Although some data suggest that a few drugs need further evaluation, at this time, renal cell carcinoma must be considered a chemotherapeutically resistant cancer.

Cytotoxic chemotherapy for advanced hormone-resistant prostate cancer

BACKGROUND

Advanced adenocarcinoma of the prostate after hormonal manipulation has been noted to be a relatively chemotherapeutic nonresponsive tumor. Earlier reviews have reported objective responses, that is, complete and partial remissions in 6.5% of 3184 patients, and the current review examines the efficacy of new agents.

METHODS

The current review consists of 26 new drug trials culled from papers and abstracts published between 1987-1991.

RESULTS

Results of these 26 drug trials found a similar trend, 8.7% (95% confidence interval, 6.4-9.0%), indicating that hormone-resistant adenocarcinoma of the prostate still fails to respond to most cytotoxic agents. The most interesting of the new therapeutic agents is the combination of vinblastine plus estramustine. Only six agents had an objective response rate greater than 10%, such as vinblastine by continuous infusion, trimetrexate, mitoguazone, and estramustine. The recent introduction of radioactive-labeled monoclonal antibodies is intriguing and these will undoubtably be used as carriers for radiotherapeutic and cytotoxic compounds.

CONCLUSIONS

Although multidrug resistance may explain the marginal efficacy of cytotoxic drugs, methods to overcome such resistance and, more importantly, new classes of agents must be developed. In addition, reliable disease markers must be found for osseous and visceral metastases to avoid the prevailing confusion in evaluating more precisely the destruction of prostate cancer cells.

Altered expression of the retinoblastoma gene product: prognostic indicator in bladder cancer

BACKGROUND

It has been reported that 50%-70% of patients with bladder cancer experience recurrence after initial successful treatment and about 10%-20% of these patients die of the disease. Despite precise pathologic staging and grading, we are unable to predict clinical outcome in all patients. The retinoblastoma-susceptibility (RB) gene, a prototype of tumor suppressor genes, has recently been associated with development and/or progression of bladder cancer, as well as sarcoma and small-cell lung cancer. In transitional cell carcinomas of the bladder, we have observed altered expression of the Rb gene product--a nuclear phosphoprotein thought to function as a cell cycle regulator.

PURPOSE

The aim of this study was to investigate the hypothesis that altered patterns of Rb expression correlate with prognosis in bladder cancer.

METHODS

Expression of the RB gene was evaluated in specimens from 48 primary bladder tumors obtained by cystectomy or transurethral resection. Rb protein expression was correlated with disease outcome in these patients. Rb expression was examined by immunohistochemistry, using the mouse monoclonal antibody Rb-PMG3-245 on frozen tissue sections. Computerized image analysis was used to quantify the level of Rb protein in individual tumor cells.

RESULTS

The overall 5-year disease-free survival was 66%, with a median follow-up of 42 months. Normal levels of Rb protein expression were found in 34 patients (Rb-positive group). A spectrum of altered patterns of expression from undetectable levels to heterogeneous expression, however, was observed in 14 patients (altered Rb group). Of the 38 patients with muscle-invasive tumors, 13 were categorized as having altered expression of Rb protein. Only one of 10 patients with superficial carcinomas had altered expression of Rb protein. The 5-year survival was significantly decreased in patients with altered Rb protein compared with the survival in patients with positive Rb expression (P less than .001).

CONCLUSIONS

The results suggest that tumors exhibiting decreased expression of the RB gene-coded product (Rb protein) had a more aggressive biological behavior than those that expressed the Rb protein in the majority of their tumor cells.

IMPLICATIONS

This study demonstrates that altered patterns of Rb protein expression may be an important prognostic variable in patients presenting with invasive bladder cancer.

Estramustine and vinblastine: use of prostate specific antigen as a clinical trial end point for hormone refractory prostatic cancer

The combination of estramustine phosphate and vinblastine sulfate, 2 agents with separate and unique antimicrotubular effects, has demonstrated additive cytotoxicity against the DU145 human prostate derived cell line in vitro. We evaluated this combination in 25 patients with progressive hormone refractory prostate cancer. Of 24 patients with an elevated prostate specific antigen (PSA) level at the start of treatment 13 (54%, 95% confidence limits 34 to 74%) had a greater than 50% decrease in PSA levels on at least 3 consecutive biweekly determinations. The median decrease in PSA in responding patients was 64% (mean 71.7%) and the median duration of response was 7 months. In 5 patients with bidimensionally measurable disease 2 partial responses were observed. Treatment was well tolerated, with mild and manageable toxicity. This is a well tolerated outpatient treatment regimen for patients with hormone-refractory prostatic cancer which deserves further investigation.