Toxicities of human recombinant interferon-alpha 2 in patients with advanced prostate carcinoma

Effects of interferons and double-stranded RNA on human prostate cancer cell apoptosis

Prostate cancer is the second most commonly diagnosed cancer among men in the United States. Prostate cancer therapy is severely hampered by lack of response and development of resistance to conventional chemotherapeutic drugs in patients. Therefore, the development and discovery of new drugs have become an urgent clinical need. Interferons (IFNs), a family of pleiotropic cytokines, exert antitumor activities due to their anti-proliferative, immunomodulatory and proapoptotic functions. Here, we report that pretreatment of prostate cancer PC-3 cells with IFNs sensitized these cells to double-stranded RNAs (dsRNAs)-induced apoptosis. The enhancement effect of IFN treatment was dependent on IFN subtypes, in particular, IFN γ. In comparison with IFN α or β, IFN γ treatment remarkably augmented apoptosis in PC-3 cells induced with polyinosinic:polycytidylic acid (poly I:C), a synthesized form of dsRNA. We demonstrated that IFN-signaling was necessary for these effects by using mutant cell lines. Transfection of 2-5A, the activator of RNase L, or silencing of dsRNA-dependent protein kinase R (PKR) by siRNA did not have any significant impact on this event, suggesting that neither RNase L nor PKR was involved in poly I:C/IFN γ-induced apoptosis in the cells. Further investigation of the apoptotic pathway revealed that Bak, a pro-apoptotic member of the Bcl-2family, was synergistically up-regulated by IFN γ and poly I:C, whereas other members of the family were not affected. Knocking down of Bak demonstrated its contribution to poly I:C/IFN γ-induced apoptosis in the cells. We believeour findings will precipitate the design of novel therapeutic strategies for prostate cancer.

Low dose of interferon-α improves the clinical outcomes of docetaxel in patients with castration-resistant prostate cancer: A pilot study

The aim of this study was to test whether a low dose of interferon-α-2b (IFN-α2b) enhances the clinical outcome of docetaxel (DXT) in patients with castration-resistant prostate cancer (CRPC). A prospective controlled trial of 40 CRPC patients receiving 5 mg of prednisone twice daily was conducted, where patients were randomly assigned to be administered 75 mg/m² DXT plus 3 mIU/m² IFN-α2b (group A, n=20) or 75 mg/m² DXT alone (group B, n=20). The prostate-specific antigen (PSA) response, tumor response, progression-free survival (PFS) and overall survival (OS) were evaluated. There was no statistically significant difference in PSA response rate between groups A and B (65 vs. 47.4%, P=0.341). The tumor response rate in group A was significantly greater compared with that in group B (55 vs. 21.1%, P=0.048). The median PFS was longer in group A compared with that in group B (10 vs. 8 months, P=0.043). There was no statistically significant difference in median OS between the two groups (19 vs. 17 months, P=0.348), but one patient displayed a complete tumor response in group A. In groups A and B, transient grade 3 to 4 neutropenia was observed in nine and six patients, grade 3 to 4 anemia was observed in three and five patients, and grade 3 to 4 general fatigue was observed in four and one patient(s), respectively. The proportion of patients with grade 3 to 4 toxicity was not statistically different between the two groups. A low dosage of IFN-α2b may improve the antitumor activity of DXT with an acceptable toxicity profile in patients with CRPC.

IL6 sensitizes prostate cancer to the antiproliferative effect of IFNα2 through IRF9

Development and progression of prostate cancer (PCa) are associated with chronic inflammation. The cytokine interleukin 6 (IL6) can influence progression, differentiation, survival, and angiogenesis of PCa. To identify novel pathways that are triggered by IL6, we performed a gene expression profiling of two PCa cell lines, LNCaP and MDA PCa 2b, treated with 5 ng/ml IL6. Interferon (IFN) regulatory factor 9 (IRF9) was identified as one of the most prevalent IL6-regulated genes in both cell lines. IRF9 is a mediator of type I IFN signaling and acts together with STAT1 and 2 to activate transcription of IFN-responsive genes. The IL6 regulation of IRF9 was confirmed at mRNA and protein levels by quantitative real-time PCR and western blot respectively in both cell lines and could be blocked by the anti-IL6 antibody Siltuximab. Three PCa cell lines, PC3, Du-145, and LNCaP-IL6+, with an autocrine IL6 loop displayed high expression of IRF9. A tissue microarray with 36 PCa tissues showed that IRF9 protein expression is moderately elevated in malignant areas and positively correlates with the tissue expression of IL6. Downregulation and overexpression of IRF9 provided evidence for an IFN-independent role of IRF9 in cellular proliferation of different PCa cell lines. Furthermore, expression of IRF9 was essential to mediate the antiproliferative effects of IFNα2. We concluded that IL6 is an inducer of IRF9 expression in PCa and a sensitizer for the antiproliferative effects of IFNα2.

Randomized phase II trial of first-line treatment with sorafenib versus interferon Alfa-2a in patients with metastatic renal cell carcinoma

PURPOSE

An open-label, phase II study to evaluate progression-free survival (PFS), overall best response, adverse events (AEs), and patient-reported outcomes with sorafenib versus interferon alfa-2a (IFN-alpha-2a) in patients with untreated, advanced renal cancer.

PATIENTS AND METHODS

A total of 189 patients were randomly assigned to oral sorafenib 400 mg twice daily or to subcutaneous IFN-alpha-2a 9 million U three times weekly (period 1). Sorafenib patients who progressed were dose-escalated to 600 mg twice daily; IFN-alpha-2a patients who progressed were switched to sorafenib 400 mg twice daily (period 2).

RESULTS

In period 1 PFS was similar for sorafenib-treated (n = 97; 5.7 months) and IFN-alpha-2a-treated patients (n = 92; 5.6 months); more sorafenib-treated patients had tumor shrinkage (68.2% v 39.0%). Common drug-related AEs (Grades > or = 3) for sorafenib were hand-foot skin reaction (11.3%), diarrhea (6.2%), and rash/desquamation (6.2%); for IFN-alpha-2a, these were fatigue (10.0%), nausea (3.3%), flu-like syndrome (2.2%), and anorexia (2.2%). Sorafenib-treated patients reported fewer symptoms, better quality of life (QOL), and greater treatment satisfaction. In period 2, 41.9% of patients who received sorafenib 600 mg twice daily (n = 43) experienced tumor reduction (median PFS, 3.6 months). After the switch to sorafenib 400 mg twice daily, tumors were reduced in 76.2% of 50 patients (median PFS, 5.3 months). AEs were mostly grade 1 to 2; no increase in AEs of grades > or = 3 occurred after sorafenib dose escalation.

CONCLUSION

In this study, sorafenib resulted in similar PFS as IFN-alpha-2a in patients with untreated RCC. However, sorafenib-treated patients experienced greater rates of tumor size reduction, better QOL, and improved tolerability. Both dose escalation of sorafenib after progression and a switch to sorafenib after progression on IFN-alpha-2a resulted in clinical benefit.

Clinical trials of immunotherapy for advanced prostate cancer

There is a lack of effective therapeutic regimens for advanced hormone-refractory prostate cancer (HRPC). Recent combination regimens of chemotherapy have improved management of HRPC. Neither systemic chemotherapy nor radiation regimens have significantly improved survival. Conventional systemic cytokine therapy has had limited efficacy in the treatment of advanced prostate cancer patients and its toxicity is severe. Combinations of multiple biological response modifiers for treatment of this disease also have limited efficacy. Results from phase II trials have shown that the combination of interferon-alpha and interleukin-2 therapy and the infusion of dendritic cells primed with peptides of prostate specific membrane antigen are promising. The former showed 31% response using the National Prostatic Cancer Project criteria, and the latter showed 27% of objective partial response with a reduction of >50% prostate specific antigen level. The toxicity of these two regimens was tolerated by patients. New approaches with tumor vaccines in conjunction with cytokine gene therapy have also been investigated. The clinical responses of these trials have been limited but promising. Immunotherapy may become an effective modality of prostate cancer treatment in the future.

Progress in active specific immunotherapy of prostate cancer

Treatments available for metastatic prostate cancer have failed to demonstrate significant curative potential. Current efforts are now directed towards developments of novel strategies for the treatment of metastatic prostate cancer. Cancer immunotherapeutic strategies utilize patient immune system components to kill cancer cells. This review discusses progress in active specific immunotherapeutic approaches as potential alternative methods in the treatment of metastatic prostate cancer. Various methods of augmenting the immune response against prostate cancer are discussed including systemic cytokine adjuvant therapy, cytokine gene transduced tumor vaccines, non-antigen specific immunization, DNA and peptide vaccines plus adjuvants, as well as dendritic cell-based cancer vaccines.

Prospects of immunotherapy for the treatment of prostate carcinoma--a review

The treatment of prostate carcinoma is dependent on the stage of the disease. Patients who present with clinically localized cancer or locally advanced tumors can be potentially cured by radical prostatectomy, radiation, and hormonal therapy. However, disease progression can occur in 30-50% of patients diagnosed with clinically localized cancer. The bone is the predominant site of metastases. Metastatic prostate cancer is first treated by androgen blockade but within a few months becomes hormone refractory. Hormone refractory metastatic prostate cancer is not responsive to conventional treatments, and patients have an expected survival of less than a year. It is essential to develop new approaches for the treatment of hormone refractory metastatic disease. Immunotherapy, based on enhancement of the host immune response against the tumor, has been used as an alternative therapy for the treatment of metastatic cancers refractory to conventional therapy in particular for melanoma and renal cell carcinoma. In this review, we will summarize various immunotherapeutic approaches developed over the last 18 years, and we will address the potential of immunotherapy for the treatment of metastatic prostate carcinoma by reviewing preclinical studies and initial clinical trials performed in this field.

Effect of tumor necrosis factor-alpha and interferon-gamma on the growth of human prostate cancer cell lines

Human recombinant tumor necrosis factor-alpha (rTNF-alpha, 10(-12)-10(-8) M) inhibited the proliferation of androgen-dependent LNCaP cells by 32-56%. In contrast, proliferation of androgen-independent PC-3 and JCA-1 cells was only slightly inhibited, or not inhibited at all, respectively. Human recombinant interferon-gamma (rIFN-gamma, 500 U/ml) decreased proliferation of PC-3 and JCA-1 cells by 35% and 53%, respectively, but had no effect on LNCaP cells. Interestingly, the combination of rIFN-gamma and TNF-alpha had greater antiproliferative effects on JCA-1 cells than treatment with either cytokine alone. However, the antiproliferative effects of this combination were similar to those observed for PC-3 or LNCaP cells treated with rIFN-gamma or TNF-alpha alone, respectively. These data suggest that some forms of androgen-independent prostate cancer may benefit from a combination therapy of IFN-gamma and TNF-alpha, while the use of IFN-gamma alone may be more efficacious in others.

A phase II study of recombinant human alpha-interferon in advanced hormone-refractory prostate cancer

To determine the efficacy of recombinant human leukocyte alpha-interferon (IFL-RA) in advanced hormone-refractory prostate cancer, the authors treated 40 patients with IFL-RA administered intramuscularly at a dose of 10 x 10(6) U/m2 three times weekly. Toxicity was substantial and necessitated at least a 50% dose reduction in all but five patients during the first 1-2 months of therapy. No responses were observed in patients with bone metastases, but complete and partial regression of nodal disease were observed in two patients with extraosseous disease (overall response rate, 5%; 95% confidence interval, 0.64-17.75%). The authors conclude that IFL-RA cannot be recommended at this dose and schedule in patients with advanced prostate cancer, but additional study of its use in patients with nodal disease may be warranted.

The effect of suramin, tumor necrosis factor and interferon gamma on human prostate carcinoma

Suramin, an antiparasitic agent which has been shown to block the stimulatory effect of growth factors on certain cancers, is currently being evaluated in clinical trials and as an antineoplastic agent in patients with advanced prostate carcinoma. Preliminary studies suggested that suramin inhibits the growth in vitro of human prostate carcinoma. The present study was performed in order to evaluate the effect of suramin, recombinant human tumor necrosis factor (TNF), interferon gamma and the combination of suramin plus TNF or interferon gamma on proliferation of PC-3, a human, hormone unresponsive prostate carcinoma cell line. In medium containing 2% fetal calf serum (FCS) suramin, at doses of 10 microM, 30 microM and 100 microM (levels readily achievable in humans) inhibited proliferation of PC-3. TNF, at a concentration of 500 units/ml., induced an approximately 50% inhibition of growth of PC-3. The combination of suramin plus TNF induced a greater inhibition of growth than did either agent alone, even at the low dose of 10 microM suramin. Interferon gamma, 500 units/ml., inhibited PC-3 growth. However, the combination of interferon gamma plus suramin (30 microM) induced less inhibition of proliferation than did interferon gamma alone. These results may serve as a rationale for clinical trials employing the combination of TNF plus suramin in patients with advanced prostate carcinoma.

Divergent effects of interferons on the growth of human benign prostatic hyperplasia cells in primary culture

Epithelial cells from human benign prostatic hyperplasia tissues were grown in primary cultures for up to 21 days and the effects of interferons on the growth of the cells were investigated. Interferon-alpha (Wellferon) showed growth inhibition both in the presence and in the absence of 3 x 10(-10)M testosterone propionate (TP) whereas interferon-gamma stimulated growth in a dose dependent manner under similar conditions. Interferon-beta had little effect on growth at the dose levels used in the study. The growth inhibition by interferon-alpha can be induced after stimulation of growth is achieved either with TP or with interferon-gamma. Implications of these findings for clinical use of these lymphokines is discussed.