The core control system of intracellular iron homeostasis: a mathematical model.

Iron is a metal essential for cellular metabolism. However, excess iron available for reactions contributes to the formation of dangerous reactive oxygen species, such as the hydroxyl radical, via the Fenton reaction. Therefore, intracellular iron levels are tightly constrained by a control system of proteins. This paper contains a mathematical model, in the form of a system of five ordinary differential equations, of the core of this control system, including the labile iron pool as well as proteins that regulate uptake, storage, and export and are connected through negative feedback loops. The model is validated using data from an overexpression experiment with cultured human breast epithelial cells. The parameters in the mathematical model are not known for this particular cell culture system, so the analysis of the model was done for a generic choice of parameters. Through a mixture of analytical arguments and extensive simulations it is shown that for any choice of parameters the model reaches a unique stable steady state, thereby ruling out oscillatory behavior. It is shown furthermore that the model parameters are identifiable through suitable experiments.

Modulation of adipocyte differentiation by tumor necrosis factor and transforming growth factor beta.

Cultured TA1 adipocytes treated with tumor necrosis factor alpha (TNF) lose intracytoplasmic lipid and, over a period of days, come to resemble their predifferentiated progenitors (preadipocytes). To examine the extent to which this phenotypic reversion represents a return to a less differentiated cell, we examined three major characteristics that distinguish preadipocytes from adipocytes: (a) pattern of gene expression; (b) hormonal requirement for accelerated adipogenesis; and (c) pattern of protein synthesis. We found that within hours of TNF addition to adipocytes, mRNAs for genes whose expression is augmented during adipogenesis decreased to predifferentiated levels; in addition, like preadipocytes, TNF-treated adipocytes required exposure to hormones to accelerate adipogenesis. Further, the pattern of protein synthesis seen on polyacrylamide gels reverted to that seen before differentiation. Transforming growth factor-beta (TGF-beta) also caused a rapid decrease in expression of adipose genes when added to fully differentiated cells, an effect that was achieved by treatment with either TGF-beta 1 or TGF-beta 2. These effects were seen in the absence of a demonstrable proliferative response to either TNF or TGF-beta. Thus characteristics that define the "terminally" differentiated state in adipocytes are subject to modulation by environmental influences.

A macrophage factor inhibits adipocyte gene expression: an in vitro model of cachexia.

Certain infections and malignancies in mammals cause the development of a condition known as cachexia in which the animal continues to lose weight, often while consuming an adequate diet. When macrophages are stimulated with an endotoxin, they produce a factor or factors, termed cachectin, that inhibits the activity of fat-producing (lipogenic) enzymes in cultured adipocytes. This effect may reflect one of the physiological bases for cachexia. In the present study, clones of complementary DNA from genes whose expression is increased during the differentiation of adipocytes were used to study the molecular basis of cachectin's actions. In the presence of cachectin, the expression of the corresponding genes was reversibly and specifically inhibited. Furthermore, when mature adipocytes were exposed to cachectin, the messenger RNA's of those genes diminished and rapidly approached the levels present before differentiation.

Development of intestinal adenyl cyclase and its response to cholera enterotoxin.

Adenyl cyclase activity in intestinal membranes has been studied during development in the rabbit fetus from fetal day 17 to 10 days postnatally and in the human fetus from the 10th to the 17th wk of gestation. In the rabbit, the enzyme was already present by fetal day 17 and showed a fourfold peak rise in specific activity by 22 days. By 28 days, the specific activity had fallen toward adult levels and remained constant throughout gestation and the 1st wk of life. Fluoridestimulated activity showed a similar curve, and was 2.5-5 times the basal values. Activities in jejunum and ileum were comparable at all time points studied. Phosphodiesterase activity did not change during gestation. When fetal intestinal segments were incubated in vitro with purified cholera enterotoxin, adenyl cyclase activity in subsequently prepared membranes was increased two- to threefold. This level was not regularly further elevated by fluoride ion. Lithium ion inhibited both the basal and fluoride-stimulated enzyme activity in membranes prepared from rabbit fetuses at term. Lactase activity (reflecting the development of the microvilli) in either whole intestinal homogenates or in the membrane fractions showed a differnet pattern of development, with a rise beginning on fetal day 24 and a plateau just after birth. In intestinal membranes prepared from human fetuses, the activity of both basal and fluoride-stimulated adenyl cyclase tripled from the 10th to the 17th wk of gestation. The data both in the rabbit and in man show that intestinal adenyl cyclase is capable of responding to cholera enterotoxin quite early in gestation. In the rabbit, this occurs before the time of appearance or ville or of an enzyme marker (lactase) for microville. The results support the concept that adenyl cyclase is present in plasma membrane other than the brush border.

Expression of 92-kD type IV collagenase/gelatinase (gelatinase B) in osteoarthritic cartilage and its induction in normal human articular cartilage by interleukin 1.

We report here that a 92-kD gelatinolytic metalloproteinase is expressed as protein and mRNA in human osteoarthritic cartilage, but not in normal adult articular cartilage. Western immunoblotting demonstrated that the 92-kD gelatinolytic activity corresponded to 92-kD type IV collagenase/gelatinase (gelatinase B); mRNA for gelatinase B was identified by Northern blotting. Chondrocytes from normal cartilage also exhibited mRNA for 72-kD type IV collagenase/gelatinase (gelatinase A), tissue collagenase, and stromelysin-1, and these mRNAs were increased in osteoarthritic cartilage. Regional analysis of osteoarthritic cartilage samples from four individuals revealed that gelatinase B mRNA was expressed in grossly fibrillated areas; two of four nonfibrillated cartilage samples failed to exhibit the mRNA, but did have increased levels of mRNA for other neutral metalloproteinases. IL-1 alpha treatment of normal human cartilage explants or isolated chondrocytes induced increased levels of gelatinase B and increased mRNA for tissue collagenase and stromelysin-1. Under identical conditions, mRNA levels for gelatinase A were not increased indicating that regulation of this enzyme in human articular chondrocytes is distinct from that of other metalloproteinases. Our data showing expression of gelatinase B in fibrillated cartilage suggest that it is a marker of progressive articular cartilage degradation in osteoarthritis.

Tumor necrosis factor inhibits human myogenesis in vitro.

We examined the effects of human recombinant tumor necrosis factor-alpha (TNF) on human primary myoblasts. When added to proliferating myoblasts, TNF inhibited the expression of alpha-cardiac actin, a muscle-specific gene whose expression is observed at low levels in human myoblasts. TNF also inhibited muscle differentiation as measured by several parameters, including cell fusion and the expression of other muscle-specific genes, such as alpha-skeletal actin and myosin heavy chain. Muscle cells were sensitive to TNF in a narrow temporal window of differentiation. Northern (RNA) blot and immunofluorescence analyses revealed that human muscle gene expression became unresponsive to TNF coincident with myoblast differentiation. When TNF was added to differentiated myotubes, there was no effect on muscle gene expression. In contrast, TNF-inducible mRNAs such as interferon beta-2 still responded, suggesting that the signal mediated by TNF binding to its receptor had no effect on muscle-specific genes after differentiation.

Coordinate transcriptional and translational regulation of ferritin in response to oxidative stress.

The global increase in transcription of cytoprotective genes induced in response to oxidative challenge has been termed the antioxidant response. Ferritin serves as the major iron-binding protein in nonhematopoietic tissues, limiting the catalytic availability of iron for participation in oxygen radical generation. Here we demonstrate that ferritin is a participant in the antioxidant response through a genetically defined electrophile response element (EpRE). The EpRE of ferritin H identified in this report exhibits sequence similarity to EpRE motifs found in antioxidant response genes such as those encoding NAD(P)H:quinone reductase, glutathione S-transferase, and heme oxygenase. However, the EpRE of ferritin H is unusual in structure, comprising two bidirectional motifs arranged in opposing directions on complementary DNA strands. In addition to EpRE-mediated transcriptional activation, we demonstrate that ferritin is subject to time-dependent translational control through regulation of iron-regulatory proteins (IRP). Although IRP-1 is initially activated to its RNA binding (ferritin-repressing) state by oxidants, it rapidly returns to its basal state. This permits the translation of newly synthesized ferritin transcripts and ultimately leads to increased levels of ferritin protein synthesis following oxidant exposure. Taken together, these results clarify the complex transcriptional and translational regulatory mechanisms that contribute to ferritin regulation in response to prooxidant stress and establish a role for ferritin in the antioxidant response.

FER-1, an enhancer of the ferritin H gene and a target of E1A-mediated transcriptional repression.

Ferritin, the major intracellular iron storage protein of eucaryotic cells, is regulated during inflammation and malignancy. We previously reported that transcription of the H subunit of ferritin (ferritin H) is negatively regulated by the adenovirus E1A oncogene in mouse NIH 3T3 fibroblasts (Y. Tsuji, E. Kwak, T. Saika, S. V. Torti, and F. M. Torti, J. Biol. Chem. 268:7270-7275, 1993). To elucidate the mechanism of transcriptional repression of the ferritin H gene by E1A, a series of deletions in the 5' flanking region of the mouse ferritin H gene were constructed, fused to the chloramphenicol acetyltransferase (CAT) gene, and transiently cotransfected into NIH 3T3 cells with an E1A expression plasmid. The results indicate that the E1A-responsive region is located approximately 4.1 kb 5' to the transcription initiation site of the ferritin H gene. Further analyses revealed that a 37-bp region, termed FER-1, is the target of E1A-mediated repression. This region also serves as an enhancer, augmenting ferritin H transcription independently of position and orientation. FER-1 was dissected into two component elements, i.e., a 22-bp dyad symmetry element and a 7-bp AP1-like sequence. Insertion of these DNA sequences into a ferritin H-CAT chimeric gene lacking an E1A-responsive region indicated that (i) the 22-bp dyad symmetry sequence by itself has no enhancer activity, (ii) the AP1-like sequence has moderate enhancer activity which is repressed by E1A, and (iii) the combination of the dyad symmetry element and the AP1-like sequence is required for maximal enhancer activity and repression by E1A. Gel retardation assays and cotransfection experiments with c-fos and c-jun expression vectors suggested that members of the Fos and Jun families bind to the AP1-like element of FER-1 and contribute to its regulation. In addition, gel retardation assays showed that E1A reduces the ability of nuclear proteins to bind to the AP1-like sequence without affecting the levels of nuclear factors that recognize the 22-bp dyad symmetry element. Taken together, these results demonstrate that FER-1 serves as both an enhancer of ferritin H transcription and a target for E1A-mediated repression.

Iron addiction: a novel therapeutic target in ovarian cancer.

Ovarian cancer is a lethal malignancy that has not seen a major therapeutic advance in over 30 years. We demonstrate that ovarian cancer exhibits a targetable alteration in iron metabolism. Ferroportin (FPN), the iron efflux pump, is decreased, and transferrin receptor (TFR1), the iron importer, is increased in tumor tissue from patients with high grade but not low grade serous ovarian cancer. A similar profile of decreased FPN and increased TFR1 is observed in a genetic model of ovarian cancer tumor-initiating cells (TICs). The net result of these changes is an accumulation of excess intracellular iron and an augmented dependence on iron for proliferation. A forced reduction in intracellular iron reduces the proliferation of ovarian cancer TICs in vitro, and inhibits both tumor growth and intraperitoneal dissemination of tumor cells in vivo. Mechanistic studies demonstrate that iron increases metastatic spread by facilitating invasion through expression of matrix metalloproteases and synthesis of interleukin 6 (IL-6). We show that the iron dependence of ovarian cancer TICs renders them exquisitely sensitive in vivo to agents that induce iron-dependent cell death (ferroptosis) as well as iron chelators, and thus creates a metabolic vulnerability that can be exploited therapeutically.

Adjuvant intravesicular pharmacotherapy for superficial bladder cancer.

In 1990, bladder cancer, excluding carcinoma in situ, was estimated to contribute 49,000 cases of cancer. In men 75 years old or older, it became the fifth leading cause of cancer deaths. Of patients with bladder cancer, 75%-80% initially present with superficial bladder tumors. Treatment of these tumors has three objectives: 1) to eradicate existing disease, 2) to provide prophylaxis against tumor recurrence, and 3) to avoid deep invasion into the muscle layers of the bladder. Transurethral resection is the primary treatment to eradicate superficial bladder tumors, but 40%-80% of these tumors recur. Because of these high recurrence rates, adjuvant intravesicular pharmacotherapy with cytotoxic and immunomodulatory drugs has gained widespread use. The past two decades of clinical investigations in superficial bladder cancer have provided valuable information on the biology and treatment of the disease. Multivariate analyses have indicated that tumor grade and stage are the most important prognostic variables commonly available to the clinician to identify the patient at greatest risk of developing muscle-invasive or metastatic bladder cancer. These studies have also identified groups at low risk for tumor recurrence and invasive bladder cancer. Randomized trials have shown that recurrence rates are decreased by adjuvant intravesicular pharmacotherapy with a number of drugs: bacillus Calmette-Guérin vaccine (BCG), doxorubicin, ethoglucid (Epodyl), mitomycin-C, teniposide, and thiotepa. However, few studies indicate that adjuvant intravesicular pharmacotherapy can prevent progression to invasive bladder cancer in the high-risk patient with superficial bladder cancer. Additional clinical trials are needed to determine whether such therapy can prevent invasive and metastatic bladder cancer and improve disease-free survival in this group. In addition, the identification of tests (e.g., monoclonal antibody tests, chromosomal analyses, and tumor marker assays) that can help to identify high-risk patients is needed to better develop therapeutic strategies for superficial bladder cancer.

Effect of verapamil on doxorubicin cardiotoxicity: altered muscle gene expression in cultured neonatal rat cardiomyocytes.

Verapamil reverses multidrug resistance acquired by cancer cells during treatment with chemotherapeutic agents such as doxorubicin by inhibiting the function of P-glycoprotein. Verapamil has also been suggested to potentiate the cardiotoxicity of doxorubicin. We have recently demonstrated that selective inhibition of cardiac muscle gene expression is among the earliest events in doxorubicin cardiotoxicity. To explore the influence of verapamil on doxorubicin cardiotoxicity, we evaluated [14C]-doxorubicin accumulation, cardiac muscle gene expression by Northern blot analysis, and ultrastructural changes in cultured cardiomyocytes in the presence and absence of verapamil. Treatment with a combination of doxorubicin and verapamil for 24 h did not augment doxorubicin accumulation in cardiomyocytes, although substantial augmentation of doxorubicin accumulation by verapamil in cardiac fibroblasts was observed. Further, treatment with verapamil for 24 h did not augment the decrease in expression of muscle genes induced by doxorubicin (myosin light chain 2 slow, troponin I, M isoform creatine kinase). However, we found that verapamil reduced alpha-actin gene expression in a direct, doxorubicin-independent manner. Furthermore, the effect of doxorubicin plus verapamil on alpha-actin gene expression was additive over a wide range of doxorubicin and verapamil concentrations, resulting in a selective augmentation of doxorubicin-induced inhibition of gene expression for this single muscle protein gene. This was reflected in a substantial increase in cardiac myocyte damage when treatment with verapamil and doxorubicin was compared to treatment with doxorubicin alone by thin section electron microscopy. This suggests a possible mechanism by which verapamil may potentiate doxorubicin cardiotoxicity.

Interleukin-1 beta induces interleukin-1 receptor antagonist and tumor necrosis factor binding protein in humans.

Sustained release or high levels of interleukin-1 (IL-1) and/or tumor necrosis factor (TNF), as observed after endotoxin challenge, can produce a variety of toxicities. Naturally occurring inhibitors to IL-1 and TNF, IL-1 receptor antagonist (IL-1ra) and soluble TNF receptor forms, have been detected. These proteins may function to buffer or limit the effects of these cytokines as part of a regulatory network. As part of a clinical trial of recombinant human interleukin-1 beta (rhIL-1 beta), serial plasma samples were obtained from 6 patients with metastatic melanoma treated with 30-min infusions of rhIL-1 beta for 5 consecutive days. The presence of circulating IL-1 receptor antagonist and soluble TNF binding proteins (TNF-R55-BP and TNF-R75-BP) were assessed. A maximum 86-fold increase for IL-1ra, a 7-8-fold increase for TNF-R55-BP, and a 2-3-fold increase for TNF-R75-BP were seen 2-4 h, 1 h, and 4 h, respectively, after rhIL-1 beta infusion. On each day of the treatment, the secretion of IL-1ra and release of TNF-R55-BP was observed, but there was no accumulation above baseline value for IL-1ra before each of the 5 daily infusions. Although there was a steady decrease of the 6-h postinfusion plasma levels for IL-1ra and TNF-R55-BP over the 5 treatment days, no increase of clinical side effects was noted. Two patients had measurable levels of TNF-alpha, but no correlation to TNF-binding proteins was observed. Our data show that early after rhIL-1 beta infusion the induction of IL-1ra secretion, as well as TNF-binding protein release, is observed.

Cardiotoxicity of epirubicin and doxorubicin: assessment by endomyocardial biopsy.

Forty-two evaluable endomyocardial biopsies were obtained from 29 patients treated with epirubicin, the 4'-epimer of doxorubicin in cumulative doses ranging from 147 mg/m2 to 888 mg/m2. In this study of the Northern California Oncology Group, myofibrillar loss and sarcoplasmic vacuolization were identified and shown to be identical to those previously described for doxorubicin. However, when these biopsies were compared to 119 biopsies obtained from 98 patients treated with doxorubicin, milligram for milligram, epirubicin caused less endomyocardial injury than doxorubicin (P = 0.0013). Age, sex, type of primary malignancy, prior cardiac disease, and hypertension did not influence the degree of histologically demonstrated anthracycline injury induced by epirubicin.

Effects of Anti-repulsive Guidance Molecule C (RGMc/Hemojuvelin) Antibody on Hepcidin and Iron in Mouse Liver and Tumor Xenografts.

OBJECTIVE: Hepcidin is a peptide hormone produced by the liver that regulates systemic iron homeostasis. Hepcidin is also synthesized by tumors, where it contributes to tumor growth by increasing the tumoral retention of iron. Targeted reduction of hepcidin may therefore be useful in reducing tumor growth. H5F9-AM8 is an antibody in preclinical development for the anemia of chronic disease that reduces hepcidin synthesis by binding to RGMc, a co-receptor involved in the transcriptional induction of hepcidin by BMP6. We explored the ability of H5F9-AM8 to act as an anti-tumor agent. METHODS: Effects of anti-hemojuvelin antibody on hepcidin synthesis were assessed by qRTPCR in tissue culture and in tumor xenografts and livers of mice treated with H5F9-AM8 or saline. Tumor growth was assessed using caliper measurements. Serum iron was measured colorimetrically and tissue iron was measured using western blotting and inductively coupled mass spectrometry. RESULTS: In tissue culture, the anti-hemojuvelin antibody H5F9-AM8 significantly reduced BMP6-stimulated hepcidin synthesis in HepG2 and other cancer cells. In mice, H5F9-AM8 reduced hepcidin in the liver and increased serum iron, total liver iron, and liver ferritin. Although hepcidin in tumors was also significantly decreased, H5F9-AM8 did not reduce tumor iron content, ferritin, or tumor growth. CONCLUSION: Anti-hemojuvelin antibody successfully reduces hepcidin in both tumors and livers but has different effects in these target organs: it reduces iron content and ferritin in the liver, but does not reduce iron content or ferritin in tumors, and does not inhibit tumor growth. These results suggest that despite their ability to induce hepcidin in tumors, the anti-tumor efficacy of systemic, non-targeted hepcidin antagonists may be limited by their ability to simultaneously elevate plasma iron. Tumor-specific hepcidin inhibitors may be required to overcome the limitations of drugs that target the synthesis of both systemic and tumor hepcidin.

The biology and treatment of superficial bladder cancer.

Management of the superficial bladder cancer patient consists of two complementary but separate therapeutic goals: treatment of the existing tumor(s) and prevention of tumor recurrence. At present, the stage, grade, and multicentricity are the major determinants in the natural and therapeutic history of the disease. Although intravesical instillation of chemotherapeutic agents has been used for greater than 20 years, neither its exact role nor the optimal dose or schedule of administration have been established. To date, no dramatic differences in efficacy between the agents commonly used for intravesical chemotherapy, either as definitive therapy or prophylaxis, have been appreciated. These agents do appear to lower the recurrence rate as well as extend the disease-free interval. Since the most thorough experience is with thiotepa, it is the drug against which other agents should be compared in terms of both efficacy and toxicologic evaluation. Different administration schedules and methodologies need further study, such as the utility of continuous bladder irrigation, the use of sequential chemotherapeutic agents to gain cell synchronization, and the use of multiple drug regimens. Because there are multiple factors that influence the occurrence and recurrence of bladder cancer, combined modality therapy deserves testing. Modes of therapy that could be used together because they act through different mechanisms are intravesical chemotherapy, radioactive needle implants, carcinogen modifiers such as pyridoxine, chemoprotective agents such as retinoic acid, and immune stimulants such as BCG. These studies should be performed in a randomized prospective controlled fashion, which may require cooperative multi-institutional involvement to accrue adequate numbers of patients. At this time there are a number of important questions that remain to be answered concerning the treatment of superficial bladder cancer: (1) does this mode of therapy affect overall survival, (2) does prophylactic intravesical chemotherapy alter the incidence of subsequent muscle invasive disease, (3) does intravesical chemotherapy alter the sites, incidence, or responsiveness to systemic chemotherapy of subsequent metastatic disease, and (4) and what is the optimal timing and duration of prophylactic therapy from a cost-effectiveness standpoint?

A comparison of the quality of participation of community affiliates and that of universities in the Northern California Oncology Group.

The quality of participation in the performance of clinical trials of university members and community affiliates of the Northern California Oncology Group is evaluated and compared. The data, based on 738 patients on 33 protocols, were collected during a one year period, July 1, 1980--June 30, 1981. The comparisons are made on three types of criteria: accrual distribution, with respect to study phase and modality multiplicity; data quality, generally reflecting protocol adherence; and data completeness. The performance of the community affiliates was found to equal or surpass that of the university members in most measures. Therefore, it is concluded that the community affiliates are functioning as full and valuable participants in the Northern California Oncology Group.

Superficial bladder cancer: the primacy of grade in the development of invasive disease.

Tumor characteristics thought to predict for development of deep muscle invasion after resection of superficial bladder cancer were retrospectively analyzed in 252 patients with transitional cell carcinoma of the bladder at Stanford University Medical Center. Stage 0 patients accounted for 190 of the patient population (75.5%), while stage A and B1 comprised 51 (20%) and 11 (4.5%), respectively. The median follow-up time was 62 months. Forty-three patients subsequently developed deep muscle invasion; these included 24 (12.6%), 14 (27.5%), and 5 (45.5%) of stage 0, A, and B1 patients (P = .002), or 15 (10%), 15 (9%), and 13 (33%) of grade 1, 2, and 3 tumors (P = .001), respectively. When analyzed by univariate logistic regression, grade (P = .0001) and stage (P = .0118) were significant predictors for invasive disease. Site of tumor and number of tumors at presentation were not significant factors for invasion deep into the bladder wall. When multiple logistic regression was performed, only grade remained as a significant tumor variable to predict for invasive disease (P less than .0091). Risk of invasive disease did not appear to increase with increasing number of recurrences, remaining at approximately an 11% invasion rate through 12 recurrences. In this analysis, grade was the most significant tumor variable in superficial bladder cancer predicting for the development of invasive carcinoma. Future clinical trials for definitive or adjuvant therapy of this disease must stratify for this variable.

Diagnostic accuracies of clinical studies in patients with small cell carcinoma of the lung.

The diagnostic accuracy of clinical studies done in 38 patients with small cell carcinoma of the lung was analyzed by comparing the test results to autopsy findings. The chest radiograph was accurate in 31 of 38 patients (82%). The accuracy of the chest radiograph was higher in evaluating the lung parenchyma and mediastinum than in evaluating the hilum and pleura. Computerized tomographic brain scan was accurate in 11 of 12 patients. However, all the diagnostic studies used for assessing the liver, including physical examination, serum liver enzyme and bilirubin measurements, and radionuclide liver scan, were only moderately accurate. More accurate studies for detecting liver metastasis in patients with small cell carcinoma are needed.

Alpha-interferon in superficial bladder cancer: a Northern California Oncology Group Study.

Thirty-five patients with superficial transitional carcinoma of the bladder were treated intravesically with escalating doses of recombinant alpha-2-interferon administered weekly for 8 weeks. Of the 19 patients with high-grade intraepithelial neoplasia (17 carcinoma in situ [CIS], two severe dysplasia, all cytology positive), six (32%) had complete resolution of all histologic and cytologic evidence of disease (complete response). An additional three patients (16%) had complete resolution of CIS, but the interval appearance of a low-grade transitional cell neoplasm. Five (26%) had a partial response (complete resolution of all evidence of CIS on multiple bladder biopsies but persistently positive cytologic preparations). Sixteen patients with recurrent papillary tumors and extensive prior therapy were also treated. Four (25%) had a complete response. Twenty-three of the 35 patients had prior intravesical therapy. Seven of the 23 (30%) patients with prior intravesical chemotherapy or immunotherapy had a complete or partial response to interferon, while eight of the 12 patients (67%) without prior intravesical treatment responded. These responses were achieved with minimal local and systemic toxicity. Of the ten complete responders, five remain in continuous unmaintained remission for 18+ to 37+ months. Intracavitary alpha-2-interferon is an effective new treatment for some patients with bladder cancer.

Weekly doxorubicin in endocrine-refractory carcinoma of the prostate.

Twenty-five patients with endocrine-refractory prostatic carcinoma were treated with doxorubicin, 20 mg/m2 given weekly. All patients had prior hormonal therapy (68% had two or more prior hormonal maneuvers), and 21 (84%) had prior therapeutic or palliative irradiation. Median Karnofsky performance status at the time of entry was 70. Hemoglobin was less than 12.0 g/dL in 15 patients. Bidimensional tumors were present in 12 patients in 19 disease sites; four of the 12 patients (33%) responded in eight of the 19 sites (42%); and three of eight patients had a 75% decrease in prostatic nodule size. Ten of 20 evaluable patients had an improvement of 20% or greater in Karnofsky performance status and 67% (14 of 21) had marked improvement in pain. A greater than 50% reduction or normalization of acid phosphatase occurred in 19% and of alkaline phosphatase in 53%. The overall response rate by National Prostatic Cancer Project criteria was 84%. Gastrointestinal toxicity and alopecia were minimal and myelosuppression was not life threatening in any patient.