Current status of thalidomide and its role in the treatment of metastatic prostate cancer

Potent Anti-Cancer Properties of Phthalimide-Based Curcumin Derivatives on Prostate Tumor Cells

Metastatic castration-resistant prostate cancer is commonly treated with chemotherapy, whose effect is less than satisfactory. This raised the need for novel agents for the treatment of prostate cancer. In the present study, five phthalimide-based curcumin derivatives were synthesized and completely characterized to assess improved stability, pharmacodynamics, and radical scavenging ability. To investigate the potential application in anti-cancer therapy, the anti-proliferative activity of the synthesized molecules was determined on aggressive prostate tumor cells. We demonstrated that the K3F21 derivative has increased potency compared to curcumin, in terms of GI50, anti-proliferative and anti-migrating activities. K3F21 inhibits anchorage-dependent and -independent growth of prostate cancer cells by altering the expression of key genes controlling cell proliferation, such as Cylins D1, B1 and B2, and apoptosis, among which Puma, Noxa, and Bcl-2 family members. Finally, the anti-cancer activity of K3F21 was demonstrated by the analysis of cancer-associated PI3K/AKT, ERK, and p38 signaling pathways.

Potential inhibitory effect of LASSBio-596, a new thalidomide hybrid, on inflammatory corneal angiogenesis in rabbits

AIMS

Evaluate the effect of LASSBio-596, structurally designed as a new hybrid of thalidomide, on inflammatory corneal angiogenesis.

METHODS

Eighteen rabbits were submitted to an alkaline cauterization in the right cornea. The animals were randomly allocated to three groups: vehicle, dexamethasone and LASSBio-596. Drugs were administered by eyedrops 3 times a day for 21 days. Evaluations were performed on days 3, 6, 9, 12, 15, 18 and 21 after cauterization. At these time points, digital images of the cornea were captured in a standard fashion. The angiogenic response was measured using software that was developed specifically for this purpose. It calculated the following parameters: neovascularization area (NA), total vascular length (TVL) and blood vessel number (BVN).

RESULTS

It was observed that dexamethasone significantly decreased NA, TVL and BVN during all assessments. From the NA the angiogenesis rate (AR) was calculated in each group. Therefore, dexamethasone completely inhibited the inflammatory corneal angiogenesis with an AR of -0.001 ± 0.006 mm(2)/day, which was significantly lower (p < 0.001) than that observed after treatment with vehicle (0.078 ± 0.024 mm(2)/day) and LASSBio-596 (0.054 ± 0.012 mm(2)/day). Although LASSBio-596 reduced angiogenesis in relation to vehicle, according to NA, TVL and BVN values, this difference was not statistically significant. However, it was found that the AR as measured in the LASSBio-596 group was significantly lower (p < 0.05) than that seen in control animals, indicating a potential antiangiogenic effect.

CONCLUSION

We conclude that topical application of LASSBio-596 at 1.0% has a potential inhibitory effect on inflammatory corneal angiogenesis in rabbits.

Drug interactions of thalidomide with midazolam and cyclosporine A: heterotropic cooperativity of human cytochrome P450 3A5

There is growing clinical interest of thalidomide because of its immunomodulatory and antiangiogenic properties, despite its teratogenicity. However, little information about thalidomide has been reported regarding its precise effects on drug-metabolizing enzymes. We investigated the effects of thalidomide on cytochrome P450 (P450) enzymes in human liver microsomes to clarify the potential for possible drug interactions. Thalidomide inhibited S-mephenytoin 4'-hydroxylation activities of recombinant P450 2C19 and human liver microsomes: the apparent concentration of thalidomide producing 50% inhibition was approximately 270 microM for P450 2C19. Midazolam 4-hydroxylation activities were suppressed by thalidomide, but activities of 1'-hydroxylation and total midazolam oxidation and testosterone 6beta-hydroxylation were enhanced in the presence of thalidomide. Recombinant P450 3A5 was found to have altered kinetics at clinically relevant concentrations of thalidomide (10-30 microM). P450 3A4 was also affected, but only at higher thalidomide concentrations. Enhanced midazolam hydroxylation by thalidomide was also seen in liver microsomal samples harboring the CYP3A5*1 allele. Similarly enhanced rates of cyclosporine A clearance were observed in P450 3A5 and liver microsomes expressing P450 3A5 in the presence of thalidomide. A proposed effector constant for thalidomide corresponded roughly to its clinical plasma levels. Docking studies with a P450 3A5 homology model, based on the published structure of P450 3A4, revealed close interaction between thalidomide and the heme of P450 3A5. The present results suggest that total midazolam metabolism or cyclosporine A clearance may be increased by thalidomide in a dose-dependent manner. Unexpected drug interactions involving thalidomide might occur via heterotropic cooperativity of polymorphic P450 3A5.

Phase II trial of thalidomide and daily oral dexamethasone for treatment of hormone refractory prostate cancer progressing after chemotherapy

BACKGROUND

Responses to monotherapy corticosteroid or thalidomide have been described in prostate cancer, in chemotherapy naïve subjects.

METHODS

A total of 39 men with hormone refractory, metastatic prostate cancer who had progression during or after at least 1 conventional cytotoxic drug were treated on a single-arm Phase II trial with dexamethasone, 0.75 mg twice a day plus thalidomide, 100-400 mg/day.

RESULTS

Best-observed responses included >50% prostate-specific antigen (PSA) reduction with no radiologic progression: 10 of 39 (26%; 95% confidence interval 13% to 42%). An additional 14 of 39 had decreased PSA but then with radiologic or other progression by 12 weeks. Median progression-free survival was 84 days. Toxicity appeared treatable; there were 5 nonfatal thromboses. There was 1 subject who had complete PSA and radiologic response; 4 responders tolerated treatment without progression for more than 1 year.

CONCLUSIONS

PSA responses were frequent. Mostly, these were not durable, but some lasted more than a year. Further investigation on determinants of response durability for these or related compounds should be considered. The response rate of the present data does not support Phase III testing of this regimen for this population.

Oral thalidomide as palliative chemotherapy in women with advanced ovarian cancer

OBJECTIVE

We prospectively evaluated thalidomide, an oral agent with antiangiogenic and immunomodulatory properties, in patients with recurrent ovarian cancer, comparing the drug to standard intravenous chemotherapy and treatment holiday in terms of both progression-free interval and quality of life.

METHODS

Eligible patients had recurrent ovarian or primary peritoneal cancer and had received a minimum of two prior therapeutic regimens. Patients were offered one of three arms: (Arm A) any standard intravenous single-agent chemotherapy; (Arm B) oral thalidomide 200 mg daily; (Arm C) treatment holiday. Computed tomography (CT) scans were performed every two cycles until disease progression by Response Evaluation Criteria in Solid Tumors (RECIST) criteria. CA-125 was measured monthly as was quality of life using the Functional Assessment of Cancer Therapy (FACT-O) questionnaire.

RESULTS

Forty patients participated: 18 on Arm A; 18 on Arm B; and 4 on Arm C. The groups were comparable in terms of number of prior regimens and cycles of chemotherapy. The progression- free intervals were similar in Arm A and Arm B (3.7 versus 3.8 months). The PR/SD rate was 6.7%/60% for Arm A, and 7.7%/53.8% in Arm B. Of those treated with thalidomide, 53% had a drop in CA-125 greater than 50%, compared to 13% receiving intravenous chemotherapy. FACT-O scores at baseline and throughout treatment were equivalent.

CONCLUSION

The oral chemotherapeutic agent thalidomide appears to be comparable in response and quality of life, compared to single agent intravenous chemotherapy, in our population of heavily pretreated patients with ovarian cancer.

Initial modulation of the tumor microenvironment accounts for thalidomide activity in prostate cancer

PURPOSE

Disruption of stromal-epithelial interactions favoring prostate cancer progression may affect the phenotype of the disease. We did a preoperative study to test the hypothesis that thalidomide, an active agent in metastatic disease, is a modulator of the tumor microenvironment.

EXPERIMENTAL DESIGN

Eighteen men with high-risk prostate cancer were given thalidomide at doses escalated to 600 mg for 12 weeks, followed by radical prostatectomy. We constructed tissue microarrays from prostatectomy specimens from 15 treated patients and 15 matched untreated control subjects to assess effects of thalidomide on the tumor microenvironment. We compared the immunohistochemical expression of three groups of markers linked to angiogenesis, stromal-epithelial interactions, or the epithelial compartment. Levels of circulating basic fibroblast growth factor, interleukin-6, tumor necrosis factor-alpha, and vascular endothelial growth factor were also assessed.

RESULTS

Thalidomide was well tolerated and induced a median reduction in prostate-specific antigen of 41% without affecting testosterone. Tissue microarray analyses indicated modulation of vascular marker expression accompanied by a reduction in microvessel density in the treated group. Comparison of broader stromal-epithelial interaction markers between treated and control groups suggested a transition to a less aggressive phenotype as a result of thalidomide treatment. Hedgehog signaling was attenuated and the ratio of matrix metalloproteinases to E-cadherin shifted to favor E-cadherin. No differences were noted in proliferation or apoptosis in the epithelial compartment.

CONCLUSIONS

These findings are the first clinical evidence to support the hypothesis that the reported thalidomide clinical efficacy is attributable to early modulation of the tumor microenvironment and suggest that stromal-targeting therapies will be effective against prostate cancer.

Suppression of Urokinase Receptor Expression by Thalidomide Is Associated with Inhibition of Nuclear Factor κB Activation and Subsequently Suppressed Ovarian Cancer Dissemination

Thalidomide has been used to treat a variety of diseases ranging from alleviation of autoimmune disorders to prevention of metastasis of cancers. It has been shown previously that increased levels of urokinase-type plasminogen activator receptor (uPAR) correlate well with higher invasive phenotype. We examined whether thalidomide is able to suppress the expression of uPAR mRNA and protein in human ovarian cancer cell line HRA and human chondrosarcoma cell line HCS-2/8. Here, we show that: (a) thalidomide suppresses the expression of constitutive and transforming growth factor-beta1 (TGF-beta1)-induced uPAR mRNA and protein; (b) a nuclear factor kappaB (NF-kappaB) activation system (phosphorylation of IkappaB-alpha and degradation of IkappaB-alpha) is necessary for the TGF-beta1-induced increase in uPAR expression, because L-1-tosylamido-2-phenylethyl chloromethyl ketone, a NF-kappaB inhibitor, reduced the uPAR production as well as mRNA expression; (c) thalidomide failed to further strengthen L-1-tosylamido-2-phenylethyl chloromethyl ketone's action; (d) the once-daily i.p. administration of thalidomide (400 microg/g body weight/d) decreased progressive growth of HRA tumors and ascites formation in an in vivo animal model; and (e) the once-daily i.p. administration of thalidomide in combination with paclitaxel (i.p., 100 microg/20 g at days 2 and 5) significantly decreased progressive growth of HRA cells in a synergistic fashion. We conclude that thalidomide down-regulates constitutive and TGF-beta1-stimulated uPAR mRNA and protein expression possibly through suppression of NF-kappaB activation. Furthermore, combination therapy with thalidomide plus paclitaxel may be an effective way to markedly reduce i.p. tumor growth and ascites in ovarian cancer dissemination.

Thalidomide and analogues: current proposed mechanisms and therapeutic usage

Microvessel density is a prognostic factor for many cancers, including prostate. For this reason, several studies and therapeutic approaches that target the tumor microvasculature have been attempted. Thalidomide has long been recognized as an antiangiogenic molecule. Recently, this drug has regained favor as an anticancer agent and is in clinical trial for multiple myeloma and prostate cancer, among others. This article will briefly review the proposed mechanisms of action for thalidomide, discuss why these activities are of therapeutic value in diseases currently undergoing clinical trials, and summarize the current status of clinical trials for prostate cancer. The focus will be predominantly on the relationship of thalidomide to angiogenesis, as well as on the future and potential value of thalidomide-inspired structural derivatives.

Thalidomide in cancer medicine

Thalidomide, an oral agent with antiangiogenic and immunomodulatory properties, is being investigated extensively in the management of advanced cancer. Multiple studies with large numbers of patients have confirmed that this drug has significant activity in multiple myeloma. Some patients with myelofibrosis or myeodysplatic syndromes may reduce their need for transfusions after thalidomide treatment. The activity of thalidomide in solid tumors is less prominent. Studies in Kaposi's sarcoma, malignant melanoma, renal cell carcinoma and prostate cancer appear more promising especially when thalidomide is combined with biological agents or with chemotherapy. Limited activity was demonstrated in patients with glioma, while thalidomide appears to be inactive in patients with head and neck cancer, breast or ovarian cancer.