Prolonged imiquimod treatment and graft-versus-host reaction: histological mimicry in the skin infiltration pattern of the monocyte-macrophage-dendrocyte lineage

Management of relapsed cutaneous T-Cell lymphoma following allogeneic hematopoietic stem cell transplantation: Review with representative patient case

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment option for patients with refractory cutaneous T-cell lymphoma (CTCL) through replacement of the bone marrow responsible for lymphoma cells and possibly induction of a graft-versus-lymphoma effect. However, allo-HSCT is not always curative; relapse of CTCL occurs in about half of patients post-transplant. Treatment of relapsed CTCL after allo-HSCT is challenging because post-transplant patients are at high risk of graft-versus-host disease, and this condition may be precipitated or exacerbated by standard CTCL therapies. The benefit of each potential therapy must therefore be weighed against its risk of graft versus host disease (GVHD). In this article, we review the management of relapsed CTCL after allo-HSCT. We begin with an exemplative patient whose relapsed Sezary syndrome was successfully treated without development of GVHD. We also report high-throughput T-cell receptor sequencing data obtained during the patient's disease relapse and remission. We then review general guidelines for management of relapsed CTCL and summarize all reported cases and outcomes of relapsed CTCL after transplant. We conclude by reviewing the current CTCL therapies and their risk of GVHD.

Protomyofibroblast Pathway in Early Thermal Burn Healing

Wound healing following partial thickness thermal burns is commonly hampered by the risk of hypertrophic scarring. Skin myofibroblast (MF) density is commonly increased in postburn healing. The transition between fibroblast-like cells and α-smooth muscle actin (SMA)+ MF possibly begins with CD14+ monocytes, evolving to CD14+ CD34+ fibrocytes, followed by β-SMA+ protomyofibroblast (PMF) maturation. Skin biopsies from 25 burn patients were collected about 1 and 4 weeks after injury. Immunohistochemistry was performed using monoclonal antibodies to α-SMA, β-SMA, factor XIIIa, lysozyme, Mac 387, CD14, CD117 and Ulex europaeus agglutinin-1 (UEA-1). The set of Mac 387+ and CD14+ monocytes was accompanied by both CD34+ fibrocytes and factor XIIIa+ dendrocytes. By contrast, β-SMA+ PMF were rare. Of note, α-SMA+ MF were more abundant at week 4 than at week 1 (p < 0.01). The UEA-1+ endothelial cells showed marked variations in their dermal distribution, irrespective of the densities in the other scrutinized cells. In conclusion, healing of partial thickness thermal burns involves a diversity of cell types including PMF. In the present samples, the PMF density remained low. © 2015 S. Karger AG, Basel.

Toxic Epidermal Necrolysis and Graft-versus-Host Reaction: Revisiting a Puzzling Similarity

Drug-induced toxic epidermal necrolysis (TEN) and acute cutaneous graft-versus-host reaction (GVHR) under immunopreventive therapy share some histopathological resemblance. So far, there are no serum biomarkers and no immunohistochemical criteria distinguishing with confidence and specificity the skin lesions of TEN and GVHR. Both diseases present as an inflammatory cell-poor necrotic reaction of the epidermis. This report compares three sets of 15 immunostaining patterns found in TEN, GVHR, and partial thickness thermal burns (PTTB), respectively. Three series of 17 skin biopsies were scrutinized. Irrespective of the distinct causal pathobiology of TEN and GVHR, similar secondary effector cells were recruited in lesional skin. Burns were less enriched in cells of the monocyte-macrophage disease. These cells likely exert deleterious effects in TEN and GVHR and cannot be simply regarded as passive bystanders. These life-threatening conditions are probably nursed, at least in part, by macrophages.

Immunization of malignant melanoma patients with full-length NY-ESO-1 protein using TLR7 agonist imiquimod as vaccine adjuvant

T cell-mediated immunity to microbes and to cancer can be enhanced by the activation of dendritic cells (DCs) via TLRs. In this study, we evaluated the safety and feasibility of topical imiquimod, a TLR7 agonist, in a series of vaccinations against the cancer/testis Ag NY-ESO-1 in patients with malignant melanoma. Recombinant, full-length NY-ESO-1 protein was administered intradermally into imiquimod preconditioned sites followed by additional topical applications of imiquimod. The regimen was very well tolerated with only mild and transient local reactions and constitutional symptoms. Secondarily, we examined the systemic immune response induced by the imiquimod/NY-ESO-1 combination, and show that it elicited both humoral and cellular responses in a significant fraction of patients. Skin biopsies were assessed for imiquimod's in situ immunomodulatory effects. Compared with untreated skin, topical imiquimod induced dermal mononuclear cell infiltrates in all patients composed primarily of T cells, monocytes, macrophages, myeloid DCs, NK cells, and, to a lesser extent, plasmacytoid DCs. DC activation was evident. This study demonstrates the feasibility and excellent safety profile of a topically applied TLR7 agonist used as a vaccine adjuvant in cancer patients. Imiquimod's adjuvant effects require further evaluation and likely need optimization of parameters such as formulation, dose, and timing relative to Ag exposure for maximal immunogenicity.

Photodynamic therapy and imiquimod immunotherapy for basal cell carcinomas

Photodynamic therapy (PDT) and topical imiquimod immunotherapy (TII) are two recently introduced treatment modalities for certain types of basal cell carcinomas (BCC). We present a review of the relevant literature and report our own findings regarding the efficacy and tolerance of PDT and TII in the treatment of BCCs. According to published studies, the cure rates range from 75-95% for PDT and 42-100% for TII, depending on treatment modalities and BCC type. In our observations, 13 patients with nodular or superficial BCCs were treated by PDT using two courses of 3-hour topical application of methyl aminolevulinate, followed by 8 minutes illumination (lambda = 634 nm, e = 37J/cm2). Biopsies were taken before and one month after PDT. Side effects including pain and crusting were assessed. Eight patients with superficial BCC were treated by TII using 3 monthly courses each consisting of 3 weekly applications for 3 weeks followed by one week out of treatment. Biopsies were taken before and after 3 months of TII. Adverse reactions including erythema, oozing, ulceration, and crusting were recorded. Clinico-histological cure was obtained in 12/13 PDT cases as assessed after 1 month, and in 6/8 TII cases after 3 months. Minimal pain during illumination and crust formation were observed in 7/13 and 3/13 PDT cases, respectively. Variable erythema, oozing, ulceration, and crusting were observed in all TII-treated lesions. It is concluded that PDT represents an active and well tolerated alternative treatment for both nodular and superficial BCCs. TII also shows activity, although the tolerance may be poor and cure needs a longer time to be obtained. The final cosmetic appearance was fine following both PDT and TII procedures. Both PDT and TII may leave intact neoplastic aggregates inside the skin. They cannot be clinically perceived, leading to unexpected recurrences. It is stressed that the currently available efficacy information about PDT and TII deals with short term follow-up periods. A 5-year follow-up must be awaited before drawing firm conclusions.

Topical Immunomodulation in Dermatology: Potential of Toll-like Receptor Agonists

BACKGROUND

Topical immunomodulators include both immunostimulatory and immunosuppressive agents. If successful, topical immunotherapy may represent an important improvement in the therapy of inflammatory dermatoses, viral infections, and cancers of the skin and genital mucosa. Topical immunotherapy using obligate contact sensitizers such as diphencyprone or dinitrochlorobenzene has been used against viral (e.g., common warts) and autoimmune diseases (e.g., alopecia areata).

RESULTS

Newer agents such imidazoquinolines (imiquimod and resiquimod) act by cytokine secretion from monocytes/macrophages (interferon-alpha, interleukin-12, tumor-necrosis factor-alpha). The locally generated immune milieu leads to a Th1-dominance and cell-mediated immunity that have been clinically used to treat viral infections such as human papillomavirus, herpes simplex virus, and mollusca. Although these agents improve antigen presentation by dendritic cells, they also act on B cells leading to the synthesis of antibodies such as IgG2a. We have also introduced this treatment against cancerous lesions including initial squamous cell and basal cell carcinoma in immunocompetent and immunosuppressed patients. We provide examples of successful treatment of squamous cell cancer using topical imiquimod.

CONCLUSION

The available and additional Toll-like receptor agonists will help to improve the specific dermatologic therapy. Topical immunotherapy with both immunostimulatory and immunosuppressive agents bears potential for effective and patient friendly treatment of inflammatory, infectious, and cancerous skin diseases. Long-term evaluation will define the tolerability and safety profile of these novel topical agents.

Imiquimod-responsive basal cell carcinomas and factor XIIIa-enriched dendrocytes

Dermal dendrocytes (DDs) are dendritic cells that exhibit immunoreactivity for factor XIIIa, and are frequently found in conjunction with basal cell carcinomas (BCCs). Imiquimod was applied to 12 superficial BCCs every 3 days for 8 weeks. One week after completion of treatment, seven lesions appeared to have resolved, while five displayed evidence of residual BCC. Prior to initiation of treatment, the seven imiquimod-responsive BCCs were surrounded by numerous DDs, whereas the five imiquimod-resistant BCCs had fewer DDs next to them at the time of entry into the study. It appears that the pretreatment density in DDs may affect the efficacy of imiquimod in eradicating skin tumours.

Nudging epidermal field cancerogenesis by imiquimod

BACKGROUND

The coexistence of malignancies close to each other on the skin has been occasionally reported. The concept of field cancerogenesis applies to such cases. Given the purported mechanism of action of imiquimod, it should not be surprising that this treatment could inhibit epidermal field cancerogenesis.

AIM

To assess the effect of imiquimod applied twice weekly on incipient bowenoid changes disclosed in the vicinity of basal cell carcinomas.

MATERIALS AND METHOD

Biopsies were taken before treatment and after 4-6 weeks and 12 weeks of imiquimod treatment.

RESULTS

Large atypical bowenoid keratinocytes and dyskeratotic cells were cleared in time while factor-XIIIa-positive dermal dendrocytes appeared boosted and admixed with a brisk lymphocytic infiltration.

CONCLUSION

Epidermal field cancerogenesis appears to be controlled by imiquimod. Dermal dendrocytes might play a pivotal role in this regression phenomenon.