Treatment of Bowen's disease using a cycle regimen of imiquimod 5% cream

Trial watch: FDA-approved Toll-like receptor agonists for cancer therapy

Toll-like receptors (TLRs) have first been characterized for their capacity to detect conserved microbial components like lipopolysaccharide (LPS) and double-stranded RNA, resulting in the elicitation of potent (innate) immune responses against invading pathogens. More recently, TLRs have also been shown to promote the activation of the cognate immune system against cancer cells. Today, only three TLR agonists are approved by FDA for use in humans: the bacillus Calmette-Guérin (BCG), monophosphoryl lipid A (MPL) and imiquimod. BCG (an attenuated strain of Mycobacterium bovis) is mainly used as a vaccine against tuberculosis, but also for the immunotherapy of in situ bladder carcinoma. MPL (derived from the LPS of Salmonella minnesota) is included in the formulation of Cervarix®, a vaccine against human papillomavirus-16 and -18. Imiquimod (a synthetic imidazoquinoline) is routinely employed for actinic keratosis, superficial basal cell carcinoma, and external genital warts (condylomata acuminata). In this Trial Watch, we will summarize the results of recently completed clinical trials and discuss the progress of ongoing studies that have evaluated/are evaluating FDA-approved TLR agonists as off-label medications for cancer therapy.

Advances in non and minimal-invasive transcutaneous delivery of immunotherapy for cancer treatment

Cancer research has focused on figuring out what was the difference between cancer cells and the tissues within which cancer arose and developing targeted treatments for those differences. With FDA-approved treatments for more ten different cancers and more than thousand new clinical trials, immunotherapy has recently emerged as the most promising area of cancer research by improving efficacy and controlling the adverse effects. Transcutaneous delivery drug delivery offers a number of advantages for the patient because of not only its noninvasive and convenient nature but also factors such as avoidance of first-pass metabolism and prevention of gastrointestinal degradation. The purpose of this review was to highlight technological recent approaches to non and minimal-invasive delivery of immunotherapy for cancer treatment. Finally, some practical considerations and discussions for future studies in the field of transdermal immunomodulation are also included.

Imiquimod: an immune response modifier in the treatment of precancerous skin lesions and skin cancer

Actinic keratosis (AK) and basal cell carcinoma (BCC) are precancerous and cancerous skin lesions that should be treated especially when multiple or in cosmetically important areas. Apart from 5% 5-fluorouracil topical cream, which some feel is the gold standard topical treatment for AK, several invasive treatment modalities are available for AK and superficial BCC, such as cryotherapy, electrodessication, carbon dioxide laser and surgery causing patients discomfort and pain, pigmentary changes or necessitate multiple office visits. Additionally, there are precancerous lesions that necessitate non-invasive treatment with good esthetic results or skin cancer refractory to invasive techniques. Imiquimod is an immune response modifier approved by the FDA for the treatment of AK and superficial BCC lesions and its use is gradually expanded to various off-label precancerous and cancerous skin lesions.

Treatment of Bowen's disease with topical 5% imiquimod cream: retrospective study

BACKGROUND

Topical 5% imiquimod cream is an FDA-approved treatment for superficial basal cell carcinomas. It has also been utilized in the treatment of Bowen's disease (squamous cell in situ). The current literature on this subject, however, is scant, and this treatment is only validated by case reports and two small open label studies.

OBJECTIVE

The objective was to assess the efficacy of topical 5% imiquimod cream in the treatment of squamous cell in situ in a larger open-label case series. METHODS A retrospective study of 49 patients was performed.

RESULTS

Forty-two of the 49 (86%) patients in the study had a complete response with topical imiquimod. The remaining 7 (14%) failed therapy and required additional treatments. The mean follow-up duration was 19 months, with a range of 1 to 44 months.

CONCLUSION

Topical 5% imiquimod cream appears to be clinically beneficial in the treatment of Bowen's disease and should be considered as a treatment option.

Therapeutic options for Bowen's disease

Multiple therapeutic options are available for treatment of Bowen's disease. The choice of therapy depends on clinical circumstance and medical practitioner experience. Newer therapies have more extensive support from the literature, but more established therapies may be preferred because of accessibility, cost and efficacy. An overview of the current therapeutic options for Bowen's disease is presented.

Guidelines for management of Bowen's disease: 2006 update

This article represents a planned regular updating of the previous British Association of Dermatologists (BAD) guidelines for management of Bowen's disease. They have been prepared for dermatologists on behalf of the BAD. They present evidence-based guidance for treatment, with identification of the strength of evidence available at the time of preparation of the guidelines.

Imiquimod 5% cream in the treatment of Bowen's disease and invasive squamous cell carcinoma

BACKGROUND

Imiquimod has been successfully used for treatment of various epithelial cutaneous neoplasms.

OBJECTIVE

Our aim was to evaluate the efficacy and tolerability of imiquimod 5% cream for treatment of Bowen's disease and invasive squamous cell carcinoma (SCC) in patients who were unsuitable candidates for surgery.

METHOD

Five Bowen's disease lesions and 7 invasive SCC lesions on 10 patients were treated with imiquimod once daily 5 times a week for a maximum of 16 weeks.

RESULTS

After 8 to 12 weeks of treatment, 4 of 5 Bowen's disease lesions (80%) and 5 of 7 invasive SCCs (71.4%) showed complete clinicopathologic regression. The remaining 3 lesions showed partial regression after 16 weeks of treatment. No recurrence has been detected after a follow-up period of 24 to 38 months (mean, 31 months).

LIMITATIONS

The study is an open-label clinical trial on a small number of selected patients, with lack of excision with serial step sections.

CONCLUSION

Topical application of imiquimod 5% cream might represent an alternative topical treatment to surgery in selected cases of Bowen's disease and invasive SCC.

[Spindle-cell carcinoma in situ treated with 5% imiquimod]

We present the case of a 70-year-old woman with no personal history of interest who presented to her physician with a plaque in the right infraumbilical region whose largest diameter measured nine centimeters. The clinical and histological diagnosis was Bowen's disease. She was treated with 5 % imiquimod cream, once a day, four times a week, for eight weeks, with an excellent response. One year after treatment, no new lesions have appeared in the treated area.

Topical therapy with imiquimod for eyelid lesion

Herein a case of clinically diagnosed lower eyelid lesion treated with topical imiquimod is reported. Macroscopic resolution of the lesion occurred 4 weeks after treatment with good cosmetic result. This is the first reported successful case of using this drug in treating eyelid lesion involving the lid margin.

The role of toll-like receptors in the pathogenesis and treatment of dermatological disease

Toll-like receptors (TLR) are crucial players in the innate immune response to microbial invaders. These receptors are expressed on immune cells, such as monocytes, macrophages, dendritic cells, and granulocytes. Importantly, TLR are not only expressed by peripheral blood cells, but their expression has been demonstrated in airway epithelium and skin, important sites of host-pathogen interaction. Host cells expressing TLR are capable of recognizing conserved pathogen-associated molecular patterns, such as lipopolysaccharide and CpG DNA, and their activation triggers signaling pathways that result in the expression of immune response genes and cytokine production. As TLR are instrumental in both launching innate immune responses and influencing adaptive immunity, regulation of TLR expression at sites of disease such as in leprosy, acne, and psoriasis may be important in the pathophysiology of these diseases. Furthermore, since TLR are vital players in infectious and inflammatory diseases, they have been identified as potential therapeutic targets. Indeed, synthetic TLR agonists such as imiquimod have already established utility in treating viral pathogens and skin cancers. In the future, it seems possible there may also be drugs capable of blocking TLR activation and thus TLR-dependent inflammatory responses, providing new treatment options for inflammatory diseases.

Topical Immunotherapy: What's New

Further understanding of the pathogenesis of dermatologic conditions at a molecular level has led to targeted therapies. The topical immune response modifiers have contributed significantly to the treatment of cutaneous diseases. New topical remedies, particularly the Toll-like receptor agonists and calcineurin inhibitors, have added to the clinical armamentarium and have further advanced clinicians' ability to treat a wide variety of benign, premalignant, and malignant conditions. Furthermore, these agents have contributed to the understanding of the disease process. The next decade will witness even greater advances in targeted immunotherapies for dermatologic disease.

Imiquimod as a dermatological therapy

Imiquimod is the first of a new class of drugs (immune response modifiers) to become commercially available. It is approved in many countries for the treatment of genital warts caused by the human papilloma virus infection. However, there are reports of its use in a variety of dermatological conditions, such as basal cell carcinomas, actinic keratoses, lentigo maligna, common warts and molluscum contagiosum. Its mechanism of action is through stimulation of the T helper cell Type 1 (Th1) immune response via activation of cell surface pathogen recognition receptors (mainly toll-like receptor 7). This activation stimulates the immune system's own defence mechanism against both virally infected and tumour cells. Imiquimod and other analogues show promise in the prophylactic treatment of skin tumours in some patients, especially those who are immunocompromised.

Imiquimod for the treatment of skin cancer

Imiquimod is a topically applied immunomodulator. Although initially approved for genital and perianal warts, dermatologists have prescribed this compound for many neoplastic and nonneoplastic skin conditions. The US Food and Drug Administration recently approved imiquimod for the treatment of actinic keratoses. This article reviews the literature on imiquimod in the treatment of cutaneous malignancies.

Outcomes, risk of other malignancies, and need for formal mapping procedures in patients with perianal Bowen's disease

PURPOSE

Local excision is standard treatment for Bowen's disease, but controversy exists over the incidence of synchronous and metachronous cancers as well as the role of a preexcision mapping procedure.

METHODS

The medical records of 25 patients treated for perianal Bowen's disease between 1978 and 2001 were retrospectively reviewed.

RESULTS

There were 11 men and 14 women with a mean age at diagnosis of 47.9 +/- 14.9 years. The majority of patients (72 percent) had symptom-driven biopsies. Presentation included pruritus (56 percent), mass (28 percent), bleeding (24 percent), and anal pain (4 percent). The average duration of symptoms before diagnosis was 1.3 +/- 0.5 years. Two patients had microscopic disease discovered incidentally after hemorrhoidectomy and underwent no further treatment. Twenty-three patients underwent wide local excision, of which 19 (83 percent) had a formal mapping procedure. On final pathology, 23 patients (92 percent) had clear margins. There were three recurrences (mean time to recur 2.0 +/- 1.0 years), including the two patients who had positive margins after wide excision (1 after mapping) and one patient who had clear margins after mapping. Five patients (20 percent) had other carcinomas (1 sigmoid, 4 vulvar). At follow-up, 24 patients were alive with no evidence of Bowen's disease and 1 patient was dead secondary to sigmoid cancer with no evidence of Bowen's disease.

CONCLUSIONS

Wide excision of perianal Bowen's disease results in excellent local control, although this is highly dependent on clear pathologic margins. A formal mapping procedure does not preclude recurrence. Initial screening and follow-up regimens are not uniform because of the wide range of treatment options available.

Topical treatment strategies for non-melanoma skin cancer and precursor lesions

The ability to manage non-melanoma skin cancers and pre-malignant lesions with topical pharmacologic agents is highly compelling. This article examines currently available products and discusses their emerging roles and limitations. These include fluorouracil, diclofenac sodium, imiquimod, and photodynamic therapy.