Intralesional Antigen Immunotherapy for the Treatment of Warts ...

Am J Clin Dermatol (2013) 14:253–260 DOI 10.1007/s40257-013-0018-8

LEADING ARTICLE

Intralesional Antigen Immunotherapy for the Treatment of Warts: Current Concepts and Future Prospects Ahmad Nofal • Eman Salah • Eman Nofal Ayman Yosef

•

Published online: 29 June 2013 Ó Springer International Publishing Switzerland 2013

Abstract Many destructive and immunotherapeutic modalities have been used for the management of warts; however, an optimal treatment with high efficacy and absent or low recurrence has not been explored to date. Recently, the use of intralesional immunotherapy with different antigens has shown promising efficacy in the treatment of warts. We review the different aspects of this new modality, including candidates, types of warts treated, dosage, number and interval between treatment sessions, mode of action, efficacy, adverse effects, recurrence rate, advantages, disadvantages, current place and future prospects. A literature review revealed that healthy immune subjects are the best candidates, and a pre-sensitization test is usually done before the start of therapy. The dosage, the number and interval between sessions, and the success rates varied among the different studies. The mode of action is still uncertain, but is essentially mediated through stimulation of T helper-1 cell cytokine response. Adverse effects are mild and generally insignificant, and the recurrence rate is absent or low. Intralesional antigen immunotherapy seems to be a promising, effective and safe treatment modality for viral warts. Future well-designed and controlled studies would help to more clearly define its place in the challenging field of wart therapy. 1 Introduction Warts are a common dermatological problem caused by the human papillomavirus (HPV). Although a wide spectrum of therapeutic approaches has been used for the

A. Nofal (&) E. Salah E. Nofal A. Yosef Dermatology Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt e-mail: [email protected]

management of warts, none has yielded consistently effective results or succeeded in preventing recurrence in all patients. Destructive modalities are designed to remove the visibly infected lesions; however, non-visible infected tissues are not targeted by these approaches [1–4]. On the other hand, many immunotherapeutic modalities have been investigated to overcome the challenges associated with the use of destructive therapies. These include immune enhancers, either systemic such as zinc sulfate or topical such as imiquimod, immunosuppressives such as sirolimus, and proinflammatory cytokines such as interferons and interleukins. Inducers of cell-mediated immunity (CMI), such as Candida and mumps antigens, topical contact sensitizers such as diphencyprone, and a combination of the agents, are other immunotherapeutic options (Fig. 1) [5–7]. The common incidence of warts in addition to their clinical significance highlights the need for immune protection against HPV infection. This is particularly true in view of the absence of specific antiviral therapy against HPV, the variable efficacy of the available therapeutic modalities, the high incidence of adverse effects, particularly with the use of destructive approaches, and the relatively high recurrence rates associated with most of the current remedies [1, 5, 7]. Although the underlying mechanisms have not yet been fully explained, there is increasing evidence that CMI plays an important role in the resolution of human warts. Many findings and observations have suggested that wart proliferation is controlled by the cell-mediated immune system (Table 1) [7–9]. These observations have led some authors to consider whether specific targeting of CMI would stimulate the patient’s immune system to eradicate HPV, resulting in a non-destructive resolution of warts [5, 10]. On the basis of this assumption, the use of antigenic stimulants of CMI has

254 Fig. 1 Immunotherapeutic options for viral warts. Asterisk sirolimus is used for treatment of warts in organ transplant patients. DNCP dinitrochlorobenzene, DPC diphencyprone, SADBE squaric acid dibutylester, MMR measles, mumps, rubella, BCG Bacillus Calmette Gue´rin, KMWV killed Mycobacterium w vaccine, PPD purified protein derivative

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Immunotherapeutic Options for Viral Warts

Topical

Systemic

Intralesional

Contact Sensitizers DNCB, DCP, SADBE

Cytokines

Antigen

Interferons

Injection

Interleukin-2

Immune Modifiers

Immune Enhancers Cimetidine Levamisole Zinc sulfate

Imiquimod Immune Suppressives Antigens Sirolimus*

BCG, Tuberculin

Fungal

Extracted

Viral

Bacterial

proteins Tuberculin

Candida

Mumps

BCG

PPD

Trichophyton

MMR

KMWV

Table 1 Evidence for the proposed role of cell-mediated immunity in controlling warts Marked proliferation and persistence of warts in immunosuppressed individuals Widespread and rapid appearance of warts in solid organ transplant recipients Innumerable flat warts in patients with epidermodysplasia verruciformis Significant increase of CD4? T cells in the spontaneously regressing warts Clearance of untreated distant warts with the use of intralesional immunotherapy

2 Clinical Trials 2.1 Candidates Healthy immune subjects of both sexes and different ages with any type of warts, single or multiple, recalcitrant or non-recalcitrant, and of different sizes and durations are candidates for this therapeutic modality. Exclusion criteria include patients with prior allergic response to the injected antigen, acute febrile illness, past medical history of asthma or allergic skin disorders, pregnancy, lactation, and iatrogenic or primary immunosuppression [15, 17]. 2.2 Procedure

been the subject of many recent trials [11–26]. Intralesional antigen immunotherapy seems to enhance recognition of the virus by the immune system. This in turn allows clearance of both treated and untreated lesions and helps to prevent future clinical infection through induction of a long-term acquired immunity to HPV, leading to a prominent decrease in the recurrence rates [15, 17]. Herein, we review the different aspects, the current concepts and the future prospects of intralesional antigen immunotherapy in the treatment of warts.

Two different approaches have been used by various studies. In most of the studies, a pre-sensitization test is used before the start of the trial, where 0.1 ml of the antigen to be used is injected intradermally on the volar aspect of the forearm and a positive reaction required, i.e., erythema and induration of at least 5 mm in diameter within 48–72 h. Responders are enrolled in the study, and the non-responders are excluded [15, 25, 28]. In the other approach, some authors have injected the antigen directly

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Table 2 Clinical trials of intralesional antigen immunotherapy for viral warts References

Type of wart

Antigen used

Study design

Complete responsea Number

Distant response

Recurrence

No distant warts

None

Percent

D’Alessandria and Khakoo [11]

Plantar

BCG

Case report

1/1

100

Malison and Salkin [2]

Genital

BCG

Case report

0/2

0

0%

Lesions persisted

Brunk [13]

Extragenital

Candida

Placebo-controlled trial

35/41

85

NA

None

Phillips et al. [14]

Common

Candida

Retrospective

54/75

72

NA

None

Johnson et al. [15]

Extragenital

Mumps or Candida

Open-label pilot

29/39

74

78 %

One patient

Signore [16]

Common and plantar

Candida

Open-label

44/87

51

31 %

NA

Clifton et al. [17]

Recalcitrant extragenital

Mumps or Candida

Open-label

22/47

47

34 %

NA

Johnson and Horn [18]

Extragenital

Combination of Mumps, Candida and Trichophyton

Open-label

146/206

71

68 %

NA

King et al. [19]

Genital

Mumps, Candida or Trichophyton alone or in combination

Retrospective

5/10

50

40 %

NA

Kus et al. [20]

Recalcitrant extragenital

Tuberculin

Open-label

Horn et al. [21]

Common

Mumps, Candida and Trichophyton alone or in combination

Randomized controlled trial

Gupta et al. [22]

Ano-genital

KMWV

Open-label pilot

8/9

89

89 %

None

Maronn et al. [23]

Extragenital

Candida

Retrospective

48/55

87

NA

None

Fayed et al. [24]

Cervical condylomata

BCG

Non-randomized controlled trial

22/30

73

NA

None

Nofal and Nofal [25]

Common warts

MMR

Randomized controlled trial

57/70

81

85 %

None

Kim et al. [26]

Extragenital

Candida

Open-label

9/11

82

75 %

One patient

Choi et al. [27]

Large and multiple extragenital warts

MMR

Open-label

8/40

20

NA

NA

a

5/17

29

11 %

None

29/54

54

41 %

NA

Complete response is concerned with those who have completed the study, not the originally enrolled patients

BCG Bacillus Calmette Gue´rin, KMWV killed Mycobacterium w vaccine, MMR measles, mumps, rubella, NA not available

into the wart without previous sensitization, proposing that this approach would be more practical in terms of time, cost and patient compliance [18]. This has been supported by the absence of a significant relationship between the clinical response and the extent of sensitization reaction as shown by many studies [15, 17, 21]. We agree with this concept, which might be particularly true in the case of antigens with a common immune response in the population, as is the case with Candida antigen, and with the use of a combination of skin test antigens almost always associated with reactivity and in localities in which some antigens are part of the immunization schedules, as is the case with Bacillus Calmette Gue´rin (BCG) and measles, mumps, rubella (MMR) vaccines. The quantity injected usually varies between 0.1 and 0.3 ml and is given in a dose-dependent manner according to the size of the test reaction in the pre-sensitized patients. Only one wart, the largest in case of multiple lesions, is injected to derive benefit from the widespread immunological reaction associated with the antigen injection [15, 18, 25]. Warts are injected intralesionally using an insulin syringe that is held parallel with the skin surface with the bevel facing upward. The number of sessions varied from 1 to 10 and the interval between them varied from 1 to 4 weeks [7, 28].

2.3 Antigens Several reports have shown that intralesional antigen immunotherapy represents a promising therapeutic approach for the treatment of different types of warts, particularly the multiple and recalcitrant variants (Table 2) [11–27]. They have utilized different types of antigens, either as a single antigen [11–17, 20–24, 26] or as a combination of antigens [18, 19, 21, 25, 27]. These include fungal antigens such as the yeast Candida and dermatophytes, viral antigens such as MMR vaccine, bacterial antigens such as BCG vaccine and extracted proteins such as tuberculin (see Fig. 1). 2.4 Success Rates Variable success rates have been demonstrated among the studies utilizing this recent modality (Table 2) [11–27]. No definite explanation for the great variability in the response rates among these studies has been settled; however, factors related to study characteristics, including the number of studied patients, the study population selected for treatment, the number of treatment sessions and the intervals between sessions, may explain this variability (Table 3) [25, 29].

256 Table 3 Factors affecting success rates of intralesional antigen immunotherapy Study characteristics Number of studied patients Population selected for the study Number of treatment sessions Intervals between sessions Factors related to the antigen Single or combined Extent of reactivity Viable or nonviable antigen Antigenic power (vaccines may be more antigenic than skin test antigens) Dose (quantity injected) Wart characteristics Duration Number Size Site Type

The differences in the type of antigen used (single or combined and viable or nonviable), in the sensitivity to the injected antigen, in the dose and in the antigenic power (vaccines may be more antigenic than skin test antigens) may also be responsible for the variable success rates associated with this therapeutic modality [25, 28]. Moreover, factors related to the treated warts such as the type (plantar warts are less responsive), site (difficult sites such as periungual warts may be less responsive), size (huge warts are less responsive) and duration (warts of long duration may be less responsive) may also explain the variable response to intralesional antigen immunotherapy [7, 17]. Variable success rates have also been reported with the use of antigen immunotherapy by routes other than the intralesional injection, such as BCG as a topical solution [30–32], intradermal injection [33, 34] and paste form [35], and tuberculin in jelly form [36]. 2.5 Time for Complete Response The average number of treatments to complete response varied between different studies from 2.3 [16] to 5.9 [22]. As previously mentioned, this variability may also be explained by factors related to the study characteristics, antigen used, wart characteristics or a combination of these variables (see Table 3). 2.6 Clinical Variables and Therapeutic Response In most of the studies, no statistically significant association was found between the therapeutic response to intralesional

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antigen immunotherapy and the different clinical variables, including age, sex, number, site, size, duration of warts, number of treatment sessions, extent of reactivity to the injected antigen and previous therapy. This may be explained by the relatively small numbers of patients studied and the differences in the wart characteristics, injected antigens and selected populations [21–26]. It has also been postulated that the response of warts to this therapeutic modality may be related to the immune response of the patient rather than to the different clinical variables of the warts [32]. On the other hand, some authors have reported a positive association between the size of the skin test reactivity to the injected antigen and the clinical response [20, 34]. Other studies have reported a better response in the younger age groups of \40 years who have stronger immune responses as compared with the older age groups of[40 years [16, 21]. Similarly, the number of warts was a significant predictor of outcome (the smaller the number, the higher the response) in other studies [16]. A significant inverse relationship between the duration of warts and the therapeutic response to intralesional immunotherapy was also reported in some studies. This finding may be attributed to the high viral load expected to increase with the longer duration of the warts and to the increase of some soluble factors that blocked the local expression of cellular immunity against HPV in warts of long duration [16, 37]. Anyhow, a definite conclusion on the relationship between the efficacy of intralesional antigen immunotherapy and the different clinical variables might only be established after more large randomized controlled studies have been added to the literature.

3 Mode of Action The exact mechanism of action of intralesional antigen immunotherapy remains uncertain. Generally, it has been postulated that a functional host immune system is a necessary prerequisite for successful intralesional antigen immunotherapy [5, 38]. Some authors have suggested that intralesional antigen immunotherapy induces a strong nonspecific inflammatory response against the HPV-infected cells, involving both treated and untreated lesions [6, 15]. It has also been proposed that the trauma itself may cause wart resolution in previously sensitized individuals [20, 39]. Many studies have shown that successful intralesional antigen immunotherapy is associated with a predominant T helper (Th1) cytokine profile response such as IFN-c, IL-2, IL-12 and IFN-a, whereas its failure is associated with the presence of a high level of Th2 cytokines such as IL-10 and IL-4. In other words, intralesional immunotherapeutic antigens could exert their effects through stimulation of Th1 responses and inhibition of Th2 responses [15–25].


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Fig. 2 Mode of action of intralesional antigen immunotherapy. HPV human papillomavirus, IFN interferon, IL interleukin, Th1 T helper 1, Th2 T helper 2, TNF tumor necrosis factor

Moreover, it has been reported that intralesional antigen immunotherapy is associated with significant peripheral mononuclear cell proliferation in the responders as compared with the non-responders. This, in turn, promotes Th1 cytokine responses, particularly IFN-c and IL-2, which further activate cytotoxic T cells and natural killer cells to eradicate HPV-infected cells [21]. Antigen immunotherapy has also been proposed to downregulate the gene transcription of HPV through stimulation of TNF-a and IL-1 [31]. Finally, Kim et al. [26] also reported that wart resolution after intralesional Candida immunotherapy was associated with detection of immune response to HPV-57 Ll-peptide, suggesting that Ll-specific T cells may be involved in wart regression. In summary, the mode of action of intralesional immunotherapy is basically related to its ability to induce a strong cell-mediated immune reaction to alter the balance between Th1 and Th2 responses in favor of the former, leading finally to eradication of HPV (Fig. 2). 4 Adverse Effects Intralesional immunotherapy is usually associated with mild insignificant local and systemic adverse effects (Table 4).

As regards local adverse effects, immediate pain during injection that did not extend beyond the time of injection was the most frequent complaint in almost all patients. However, it was well tolerated, was not a cause of withdrawal in most of the studies [15, 17, 21], and was less than that experienced with cryotherapy [7, 17]. On the other hand, transient erythema, edema, induration at the injection site, burning sensation and pruritus were variably demonstrated. More aggressive adverse effects that are usually associated with destructive modalities such as infection, wounding, ulcers, scarring, and hypo- or hyperpigmentation were not observed in the different studies utilizing intralesional antigen immunotherapy [15–25]. Rare adverse reactions include a painful purple digit following Candida albicans immunotherapy and postimmunotherapy revealed cicatrix, which was observed in patients who had been treated with destructive therapies prior to immunotherapy [28, 40]. Flu-like illness is the most common systemic adverse effect. It usually appears within 12 h of injection and is resolved rapidly within 24–48 h by nonsteroidal antiinflammatory medications [15, 17, 21]. This reaction may be mediated through release of some of the antigen into the circulation with subsequent immunological response and elaboration of inflammatory cytokines [15]. An association

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Table 4 Adverse effects of intralesional antigen immunotherapy Adverse effect

Comment

Local Pain

Most frequent complaint

Erythema

Transient and variable

Edema and induration at injection site


Itching and burning sensation


Infection and scarring

Have not been reported

Wounds or ulcers


Pigmentary changes


Painful purple digit

Rarely reported with Candida antigen

Post-immunotherapy revealed cicatrix

May occur in patients previously treated with destructive therapies

Systemic Flu-like symptoms

Relatively common and rapidly subsiding

Anaphylaxis

May occur, but has not been reported

Autism in case of vaccines

Controversial

Granulomatous hepatitis

Reported once with BCG

BCG Bacillus Calmette Gue´rin

between vaccines such as MMR and autism has been suggested by some authors; however, extensive scientific studies have not proven such an association [41]. Also, a case of granulomatous hepatitis in a healthy adult following BCG injection into a plantar wart has been reported [11].

5 Advantages One of the important advantages of this therapeutic modality, particularly in developing countries, is its low cost. Treatment with Candida immunotherapy costs about US$1.5 per session [16], while that of MMR costs about US$2 per session [25]. Similarly, treatments with tuberculin and BCG vaccine are inexpensive and are likely to be cheaper [28]. The simple easy application into only the ‘mother’ wart, the promising efficacy, the high safety profile, and the absence of limitation of movement, scarring and pigmentary changes are other advantages of intralesional antigen immunotherapy over traditional therapies [15–25]. Many studies have also reported complete clearance of both treated and untreated warts, either near the injected wart or at distant anatomic sites, in patients presenting with multiple lesions. This observation represents a highly promising advantage of intralesional immunotherapy and might be explained by the development of a widespread CMI against HPV as a response to antigen injection [15, 17, 21, 25].

One of the most challenging issues in the treatment of warts is the high recurrence rates (up to 30 % or more) associated with most of the available therapeutic remedies that do not eradicate the viral reservoir present in adjacent tissue [3, 15, 28, 32]. In this context, several studies have shown that intralesional immunotherapy plays an important role in the reduction or even prevention of recurrences after successful therapy, a finding that represents a promising advantage over traditional therapies [11, 14, 15, 20, 22– 26]. This effect might be explained by its ability to induce CMI, which enables the body to recognize HPV, stimulates the production of memory T cells against the virus and intensifies the effector response mechanism [17, 28, 42, 43]. However, this advantage must be considered with caution in view of the small numbers of patients studied and the short-term follow-up reported in most of these studies.

6 Disadvantages One of the major drawbacks of intralesional immunotherapy is that the numbers of the available studies are few and most of them are open-labeled. This makes any recommendation or conclusion concerned with its efficacy, adverse effects, prevention of recurrence and other aspects inconclusive. In a systematic review on topical therapy for warts, Gibbs et al. [44] found no advantage in using intralesional immunotherapy over the traditional modalities because of the lack of enough well-designed, randomized, controlled trials that evaluate this recently investigated modality. In addition, these trials are limited by the absence of standardization in different aspects of intralesional immunotherapy such as the concentration and quantity of injected antigen, number of treatment sessions, intervals between sessions and follow-up period necessary for adequate evaluation of recurrence rates [7, 15, 17, 28]. Also, the restriction of candidates to otherwise healthy immune subjects excludes an important subset of patients associated with impaired immunity in which the warts are usually innumerable as is the case with organ transplant patients. In this respect, Gupta et al. [22] have reported adverse effects in the form of herpes zoster and reactivation of genital herpes in two patents with HIV, so they do not recommend use of antigen immunotherapy in immunosuppressed patients, unless larger trials document its safety. Although pain associated with the injection is relatively well tolerated by most patients [17, 25], it remains a disadvantage for children who prefer non-painful topical application and for patients with warts in very painful sites, such as those with periungual warts.


7 Current Place Among Wart Therapeutics Johnson et al. [15] have proposed that intralesional antigen immunotherapy by Candida and mumps skin test antigens might serve as a first-line treatment for immune individuals with numerous ([5) or large ([1 cm) warts and as a second-line treatment in immune individuals who have failed cryotherapy. Clifton et al. [17] have also considered that intralesional immunotherapy could be a first-line therapy for large or multiple warts in children and a second-line therapy in warts recalcitrant to standard therapy such as salicylic acid and cryotherapy. However, larger randomized controlled studies that could increase the level of evidence are needed before such a conclusion can be established. On the other hand, owing to the limited number of published randomized clinical trials, intralesional immunotherapy by Candida skin test antigen was recommended as second-line therapy for cutaneous warts and was given a B level of evidence [6]. Going with the same concept, Brodell and Johnson [45] have recommended intralesional immunotherapy as second-line therapy for plantar warts and third-line therapy for common and flat warts. Similarly, Dall’oglio et al. [46] have considered intralesional immunotherapy by different antigens as a third-line therapy for recurrent or difficult-to-treat warts. Finally, in their key recommendations for practice, Mulhem and Pinelis [7] have considered that intralesional injection with Candida or mumps skin antigen has moderate effectiveness (with evidence rating of B) for the treatment of recalcitrant warts in patients with a positive skin antigen pretest. We suggest that intralesional antigen immunotherapy may be used as a first-line therapy for multiple warts, particularly those associated with distant warts and warts at difficult sites such as periungual warts. These cases are usually unsuitable for destructive therapy, which is associated with many disfiguring and disabling adverse effects. In addition, it has the advantage of being the only treatment where injecting a single wart has resulted in clearance of warts at distant anatomic sites. It may also be used as a second-line agent for patients who have failed standard therapies for their single or few lesions.

8 Future Prospects Although it seems a simple, inexpensive, safe and effective remedy, intralesional antigen immunotherapy has not become a popular one, and the emerging reports of its use are still only slowly increasing. We hope that the publishing of more reports, particularly the well-controlled studies, would encourage more

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dermatologists to try this promising approach. We also hope that the widespread use of this approach in the near future would help to develop strict guidelines for its optimum use in the treatment of warts, including the best candidates, the optimal dosage, the number of injections, the interval between injections, the use of single or combined antigens, the adverse effects and the follow-up period. In conclusion, intralesional antigen immunotherapy is a promising therapeutic modality that warrants more clinical trials to further evaluate its effectiveness and to more clearly define its place in the treatment of warts. Conflict of interest No funding was received for the preparation of this manuscript. The authors have no conflicts of interest to declare.

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