Phase II study of alpha-interferon and 13-cis-retinoic acid in metastatic melanoma

Retinoic acid receptors: from molecular mechanisms to cancer therapy

Retinoic acid (RA), the major bioactive metabolite of retinol or vitamin A, induces a spectrum of pleiotropic effects in cell growth and differentiation that are relevant for embryonic development and adult physiology. The RA activity is mediated primarily by members of the retinoic acid receptor (RAR) subfamily, namely RARα, RARβ and RARγ, which belong to the nuclear receptor (NR) superfamily of transcription factors. RARs form heterodimers with members of the retinoid X receptor (RXR) subfamily and act as ligand-regulated transcription factors through binding specific RA response elements (RAREs) located in target genes promoters. RARs also have non-genomic effects and activate kinase signaling pathways, which fine-tune the transcription of the RA target genes. The disruption of RA signaling pathways is thought to underlie the etiology of a number of hematological and non-hematological malignancies, including leukemias, skin cancer, head/neck cancer, lung cancer, breast cancer, ovarian cancer, prostate cancer, renal cell carcinoma, pancreatic cancer, liver cancer, glioblastoma and neuroblastoma. Of note, RA and its derivatives (retinoids) are employed as potential chemotherapeutic or chemopreventive agents because of their differentiation, anti-proliferative, pro-apoptotic, and anti-oxidant effects. In humans, retinoids reverse premalignant epithelial lesions, induce the differentiation of myeloid normal and leukemic cells, and prevent lung, liver, and breast cancer. Here, we provide an overview of the biochemical and molecular mechanisms that regulate the RA and retinoid signaling pathways. Moreover, mechanisms through which deregulation of RA signaling pathways ultimately impact on cancer are examined. Finally, the therapeutic effects of retinoids are reported.

Retinoic acid and cancer treatment

Retinoic acid which belongs to the retinoid class of chemical compounds is an important metabolite of vitamin A in diets. It is currently understood that retinoic acid plays important roles in cell development and differentiation as well as cancer treatment. Lung, prostate, breast, ovarian, bladder, oral, and skin cancers have been demonstrated to be suppressed by retinoic acid. Our results also show that low doses and high doses of retinoic acid may respectively cause cell cycle arrest and apoptosis of cancer cells. Also, the common cell cycle inhibiting protein, p27, and the new cell cycle regulator, Cdk5, are involved in retinoic acid’s effects. These results provide new evidence indicating that the molecular mechanisms of/in retinoic acid may control cancer cells’ fates. Since high doses of retinoic acid may lead to cytotoxicity, it is probably best utilized as a potential supplement in one’s daily diet to prevent or suppress cancer progression. In this review, we have collected numerous references demonstrating the findings of retinoic acid in melanoma, hepatoma, lung cancer, breast cancer, and prostate cancer. We hope these observations will shed light on the future investigation of retinoic acid in cancer prevention and therapy.

Knockdown of lecithin retinol acyltransferase increases all-trans retinoic acid levels and restores retinoid sensitivity in malignant melanoma cells

Retinoids such as all-trans retinoic acid (ATRA) influence cell growth, differentiation and apoptosis and may play decisive roles in tumor development and progression. An essential retinoid-metabolizing enzyme known as lecithin retinol acyltransferase (LRAT) is expressed in melanoma cells but not in melanocytes catalysing the esterification of all-trans retinol (ATRol). In this study, we show that a stable LRAT knockdown (KD) in the human melanoma cell line SkMel23 leads to significantly increased levels of the substrate ATRol and biologically active ATRA. LRAT KD restored cellular sensitivity to retinoids analysed in cell culture assays and melanoma 3D skin models. Furthermore, ATRA-induced gene regulatory mechanisms drive depletion of added ATRol in LRAT KD cells. PCR analysis revealed a significant upregulation of retinoid-regulated genes such as CYP26A1 and STRA6 in LRAT KD cells, suggesting their possible involvement in mediating retinoid resistance in melanoma cells. In conclusion, LRAT seems to be important for melanoma progression. We propose that reduction in ATRol levels in melanoma cells by LRAT leads to a disturbance in cellular retinoid level. Balanced LRAT expression and activity may provide protection against melanoma development and progression. Pharmacological inhibition of LRAT activity could be a promising strategy for overcoming retinoid insensitivity in human melanoma cells.

A phase 2 trial of all-trans-retinoic acid in combination with interferon-alpha2a in children with recurrent neuroblastoma or Wilms tumor: A Pediatric Oncology Branch, NCI and Children's Oncology Group Study

BACKGROUND

The combination of the antiproliferative and differentiation-inducing effects of retinoids together with the antiproliferative, immunostimulatory, and differentiation-potentiating effects of interferon-alpha (IFN-alpha) were the basis for the development of this combination in pediatric patients with refractory neuroblastoma or Wilms tumor.

PROCEDURE

A phase 2 trial of all-trans-retinoic acid (ATRA), administered orally at a dose of 90 mg/m(2)/day in three divided doses for 3 consecutive days per week, and IFN-alpha2a, administered subcutaneously daily at a dose of 3 x 10(6) U/m(2)/day for 5 consecutive days per week, in 4 week cycles was performed. A two-stage design was used for each disease stratum.

RESULTS

Seventeen patients (16 evaluable) with neuroblastoma, median age 9 years, and 15 patients (14 evaluable) with Wilms tumor, median age 6 years, were enrolled. Overall, the combination was well tolerated, with headache being the most common toxicity observed. There were no complete or partial responses. The median number of cycles administered was 1 (range 1-9). Four patients with neuroblastoma had stable disease for 12 or more weeks.

CONCLUSIONS

The combination of ATRA and IFN-alpha2a was inactive in children with relapsed or refractory neuroblastoma and Wilms tumor. The lack of activity with this combination in children with refractory neuroblastoma is similar to the disappointing phase 2 results of single agent 13-cis-retinoic-acid (13cRA) and does not support further development of ATRA for children with relapsed neuroblastoma.

Prospective, Randomized, Multicenter, Double-Blind Placebo-Controlled Trial Comparing Adjuvant Interferon Alfa and Isotretinoin With Interferon Alfa Alone in Stage IIA and IIB Melanoma: European Cooperative Adjuvant Melanoma Treatment Study Group

Purpose

The combination of interferon alfa (IFNα) and isotretinoin has shown a direct antiproliferative effect on human melanoma cell lines, but it remained unclear whether this combination is more effective than IFNα alone in patients with metastatic melanoma. We evaluated safety and efficacy of IFNα and isotretinoin compared with IFNα alone as adjuvant treatment in patients with primary malignant melanoma stage IIA and IIB.

Patients and Methods

In a prospective, randomized, double-blind, placebo-controlled trial, 407 melanoma patients in stage IIA (301 patients) and IIB (106 patients) were randomly assigned to either IFNα and isotretinoin (isotretinoin group; 206 patients) or IFNα and placebo (placebo group; 201 patients) after excision of the primary tumor. IFNα was administered three times a week at a dose of 3 million units subcutaneously for 24 months. Isotretinoin at a dose of 20 mg for patients ≤ 73 kg, 30 mg for patients greater than 73 kg, or placebo daily for 24 months.

Results

A scheduled interim analysis revealed no significant differences in survival rates, with the isotretinoin group and the placebo group showing 5-year disease-free survival rates of 55% (95% CI, 46% to 65%) and 67% (95% CI, 59% to 75%), respectively, and overall 5-year survival rates of 76% (95% CI, 67% to 84%) and 81% (95% CI, 74% to 88%), respectively. The trial was stopped for futility.

Conclusion

The addition of isotretinoin to an adjuvant treatment of low-dose IFNα in patients with stage IIA and IIB melanoma had no significant effect on disease-free or overall survival and is therefore not recommended.

A single vaccination with protein-microspheres elicits a strong CD8 T-cell-mediated immune response against Mycobacterium tuberculosis antigen Mtb8.4

Efficient protein-based vaccine delivery systems are needed to achieve a persistent memory immune response capable of detecting and eliminating intracellular pathogens such as Mycobacterium tuberculosis (TB). We have developed a novel protein-microsphere formulation using the recently discovered TB antigen Mtb8.4. Immunization of mice with a single dose of this Mtb8.4-microsphere formulation resulted in both humoral and cellular responses against Mtb8.4. The Mtb8.4-specific CD8 T-cell responses following a single administration of Mtb8.4-microspheres exceeded that elicited by protein plus adjuvant following multiple immunizations. These results demonstrate the efficacy of a single dose protein-microsphere vaccine for the induction of strong cell-mediated and humoral immune responses against M. tuberculosis antigens.

Potential of interferon-alpha in solid tumours: part 1

Interferon-alpha (IFNalpha) is a pleiotropic cytokine with direct and indirect antitumour effects. These include prolongation of the cell cycle time of malignant cells, inhibition of biosynthetic enzymes and apoptosis, interaction with other cytokines, and immunomodulatory and antiangiogenic effects. The first clinical trials in solid tumours used crude preparations of natural IFNalpha and demonstrated that tumour regressions in solid tumours and haematological malignancies were possible. Since the advent of genetic engineering technology, recombinant (r) IFNalpha has been widely evaluated in solid tumours. This review discusses the use and potential of rIFNalpha in solid tumours; the first part focuses on malignant melanoma and metastatic renal cell carcinoma (RCC). In the adjuvant treatment of malignant melanoma, rIFNalpha has been tested in randomised trials in more than 6000 patients. High-dosage IFNalpha (> or =10MU) prolongs disease-free survival (DFS) but not overall survival (OS). Low-dosage IFNalpha (< or =3MU) has not been shown to prolong DFS or OS, and current data do not support its use outside clinical trials. The latest United Kingdom Co-ordinating Committee on Cancer Research meta-analysis of ten randomised trials that used adjuvant rIFNalpha has shown that there is a benefit in DFS but not OS. No conclusions can be reached for intermediate-dosage IFNalpha (5 to 10MU) until the mature results of the European Organization for Research and Treatment of Cancer (EORTC) study 18952 are available. In RCC, current evidence does not support the use of adjuvant IFNalpha. In metastatic malignant melanoma and RCC, reported response rates to rIFNalpha are approximately 15%. In a minority of responding patients, however, these responses can be long-standing. In metastatic malignant melanoma, IFNalpha combined with other cytotoxic agents with or without interleukin-2 has achieved high response rates but has not improved survival. In metastatic RCC, intermediate dosages of rIFNalpha should be used and therapy should probably be prolonged (>12 months); response depends on prognostic factors such as good performance status, whereas survival is affected by factors such as low tumour burden. Nephrectomy should therefore be considered in patients with good performance status prior to IFNalpha immunotherapy in advanced RCC, even in patients with metastatic disease. The toxicity of high-dosage IFNalpha and the lack of definite benefit on OS with high- or low-dosage IFNalpha do not support its use outside clinical trials. Data from the ongoing US Intergroup studies, the ongoing EORTC 18991 study (long-term therapy with pegylated IFNalpha) and mature data from EORTC 18952 (intermediate-dosage IFNalpha) will help establish the role of IFNalpha as adjuvant therapy in malignant melanoma.

Retinoids: present role and future potential

Vitamin A and its biologically active derivatives, retinal and retinoic acid (RA), together with a large repertoire of synthetic analogues are collectively referred to as retinoids. Naturally occurring retinoids regulate the growth and differentiation of a wide variety of cell types and play a crucial role in the physiology of vision and as morphogenic agents during embryonic development. Retinoids and their analogues have been evaluated as chemoprevention agents, and also in the management of acute promyelocytic leukaemia. Retinoids exert most of their effects by binding to specific receptors and modulating gene expression. The development of new active retinoids and the identification of two distinct families of retinoid receptors has led to an increased understanding of the cellular effects of activation of these receptors. In this article we review the use of retinoids in chemoprevention strategies, discuss the cellular consequences of activated retinoid receptors, and speculate on how our increasing understanding of retinoid-induced signalling pathways may contribute to future therapeutic strategies in the management of malignant disease.

Systemic treatment of metastatic melanoma with chemotherapy

This article reviews the use of systemic chemotherapy for the treatment of metastatic melanoma, including single-agent chemotherapy, combination chemotherapy with and without tamoxifen, and biochemotherapy.

Phase II clinical trial of recombinant alpha 2b interferon and 13 cis retinoic acid in patients with metastatic melanoma

Treatment for metastatic melanoma is limited by low response rates to single- or combination-agent chemotherapy. Recent studies have examined the role of biologic modifiers and differentiating agents. This phase II study examined the efficacy and toxicity of combining alpha-2b-interferon (IFN alpha) and 13 cis retinoic acid (cRA) in the treatment of metastatic malignant melanoma. Thirteen patients were treated with IFN alpha (5 x 10(6) units/m2 three times weekly) and cRA (1 mg/kg per day). One patient with lung and adrenal metastases had a partial response 6 months in duration and two patients had stabilization of lung metastases for 2 months. All other patients had progressive disease. Toxicity was substantial with all patients experiencing Eastern Cooperative Oncology Group grade 1-2 fatigue, myalgias, anorexia, stomatitis, and cheilitis. In addition, serum cholesterol and triglycerides were elevated in all patients. Seven patients required 50% dose reductions because of hypertriglyceridemia, fatigue associated with a significant decline in performance status, and severe stomatitis with anorexia and weight loss. One patient discontinued therapy because of a decline in performance status. This study suggests this combination of cRA and IFN alpha is inactive in the treatment of metastatic melanoma and is associated with substantial toxicity.

An Eastern Cooperative Oncology Group phase I trial of all-trans-retinoic acid and interferon-alpha: E2Y92

The Eastern Cooperative Oncology Group conducted a Phase I trial to determine the maximally tolerated doses of combination therapy with alpha interferon (IFN-alpha) and all-trans-retinoic acid (tRA). Fifty patients with incurable malignancies received IFN-alpha administered subcutaneously three times weekly, and tRA administered by mouth at bedtime. Doses were escalated between patient groups, starting at tRA dose level of 45 mg/m2 and 3 million units of IFN-alpha. Major, dose-limiting toxicities were attributable to either the tRA (rash, chelitis) or IFN (constitutional symptoms), and were observed only at tRA dose levels of 224 mg/m2 and 291 mg/m2, or 6 million units of IFN-alpha. The maximally tolerated dose level of 172.5 mg/m2 of tRA and 3 million units of IFN-alpha was well-tolerated, with no grade 3 or 4 toxicities attributable to therapy. One patient at the third dose level (75 mg/m2 of tRA and 3 million units of IFN-alpha) developed acute hepatic and renal failure and a metabolic encephalopathy of unclear etiology. We conclude that tRA and IFN-alpha may be safely administered together at the maximally tolerated dose of tRA as a single agent without unexpected side effects. The recommended doses of IFN-alpha and tRA for Phase II trials are 3 million units of IFN-alpha and 172.5 mg/m2 of tRA.

Combination of highly purified human leukocyte interferon alpha and 13-cis-retinoic acid for the treatment of metastatic melanoma

The effect of 13-cis-retinoic acid and highly purified human leukocyte interferon alpha (Alphaferon) therapy for metastatic melanoma was studied. A group of 17 patients with disseminated malignant melanoma were treated over a 6-month period. They received 60 mg 13-cis-retinoic acid/day continuously and ten cycles of interferon alpha (IFN alpha). IFN was administered by subcutaneous injection, at a daily dose of 6 x 10(6) IU Alphaferon. The 5-day treatment period was followed by an IFN-free interval of 2 weeks. We were able to observe an overall response rate of 30% with 12% complete responses (2 out of 17 patients). Sites of response included the skin, lung, liver and lymph nodes. All responses have now lasted over 6 months. Therapy was generally well tolerated and could be performed on an outpatient basis. Side-effects of this combination therapy did not exceed the established side-effects of the two substances. We also studied 2'-5'-oligoadenylate synthetase, beta 2-microglobulin and neopterin levels during the whole treatment course. All patients were within the normal range before treatment and a sharp rise occurred during each IFN cycle. The maximum being observed 24 h after the third injection. This indicates a high biological activity of IFN alpha administered cyclically during the whole treatment course. This finding also corresponds well with the absence of neutralizing antibodies before and after the whole treatment period.

Skin growths in the aged. Treatment considerations

Skin disorders are very common among elderly people. All physicians who care for this population should possess the ability to recognise common benign growths. Primary care physicians should also have the ability to recognise premalignant and malignant lesions, so that early diagnosis and treatment is possible. It is puzzling that the organ system most amenable to examination is so often overlooked in routine examinations. By simply taking the time to perform a skin examination, morbidity and mortality can be decreased. Through improvements in pharmacotherapy, particularly the development of more effective sunscreens, it may eventually be possible to markedly reduce the development of many benign and malignant skin lesions.

Retinoic acid and interferon combination studies in human cancer

Retinoic acid and interferon-alpha have limited single-agent activity in advanced cancer. Cell culture data indicate that in combination these agents have enhanced activity (modulating growth and differentiation) in a number of malignant cell types. Recent clinical work in advanced squamous cell carcinoma reports major activity with this regimen. This paper reviews the preclinical and clinical data testing retinoic acid in combination with interferons and presents recent work integrating these agents with radiotherapy in locally advanced cervical cancer.