Dose range finding pilot study for diagnostic patch testing with ME-PPD

para-Phenylenediamine (PPD) is an organic molecule, which is used in dark hair
dyes, manufactory dyes, dyed leather and rubber.(1) It is categorized in the
so-called para-group of aromatic amines. PPD is used together with a coupler
(e.g. m-aminophenol and resorcinol) and an oxidizing agent (e.g. hydrogen
peroxide) in permanent hair dyes.(2) It is estimated that 70% of all the
permanent oxidative hair dyes contain PPD.(3)

PPD is an effective hair dye because of its typical characteristics: a low
molecular weight, the ability to penetrate the hair shaft and follicle, strong
protein binding capacity, and rapid polymerization in the presence of a coupler
and an oxidizing agent. Unfortunately these characteristics make PPD also a
very potent allergen and the global cause of 4-7% of all cases of allergic
contact dermatitis.(3) Symptoms may include redness (erythema), swelling
(edema, papulation), itching, blistering (vesicles and bullae) and/or scaling.
Although the severity of the reaction, there are still patients who keep dyeing
their hair.

Sensitization to PPD and other molecules from the para-group can also be caused
by a cross-reaction between these molecules.(4,5) For example, a previously
PPD- sensitized individual can develop an allergic contact dermatitis to
p-Toluenediamine (PTD) without ever been in contact with that molecule. PTD is
another important primary intermediate in oxidative hair dyes. The
immunological causes for cross-reactivity are not fully explained yet.
Recently, a new hair dye molecule, 2-methoxymethyl-p-phenylenediamine (ME-PPD)
has been developed. The introduction of a methoxymethyl side chain into PPD
yielded a hair dye precursor with excellent hair colouring performance. Besides
that ME-PPD has significantly reduced skin sensitizing properties compared to
PPD and PTD.(6)

In a previous study cross-elicitation reactions to ME-PPD were investigated in
PPD-allergic individuals with a documented history of hair dye related allergy
and a positive diagnostic patch test response to PPD. ME-PPD was investigated
under use conditions by testing 2% ME-PPD in a hair dye test product for 30
minutes on the volar side of the forearms, followed by rinsing.
Cross-reactivity to the ME-PPD containing hair dye test product was elicited in
9/30 (30%) of PPD allergic individuals. (7) A total of 21 patients showed a
positive reaction to 2% PPD containing hair dye test product investigated under
the same use conditions as for ME-PPD. Six out of these 21 (29%) subjects
showed a positive reaction to the ME-PPD hair dye product.

In the current study we will investigate sensitization to ME-PPD by diagnostic
patch testing with different concentrations ME-PPD, to identify the optimal
patch test concentration. Moreover an open patch test will be performed on the
volar side of the forearms with ME-PPD 2%, PPD 2% and a control vehicle without
colors to provide us insight information in the clinical relevance of a
potential positive reaction to the patch test.
Furthermore we will investigate whether the assumed acetylation products of
ME-PPD (monoacetyl- and diacetyl-PPD) can elicit an allergic reaction. Since
we do not know why only a part of the PPD-allergic individuals gets sensitized
to ME-PPD a possible explanation could be that these acetylation products could
be the responsible sensitizers.


(1) Fernandez-Vozmediano JM, Padilla-Moreno M, Armario-Hita JC,
Carranza-Romero C. Pattern of contact sensitization to paraphenylenediamine and
its detection in hair dyes. Actas Dermosifiliogr 2011 Apr;102(3):206-211.
(2) Schnuch A, Lessmann H, Frosch PJ, Uter W. para-Phenylediamine: the profile
of an important allergen. Results of the IVDK. Br J Dermatol 2008
Aug;159(2):379-386.
(3) Thyssen JP, White JM, European Society of Contact Dermatitis.
Epidemiological data on consumer allergy to p-phenylenediamine. Contact
Dermatitis 2008 Dec;59(6):327-343.
(4) Xie Z, Hayakawa R, Sugiura M, Koijma H, Konishi H. Ichihara G, et al.
Experimental study on skin sensitization potencies and cross-reactivities of
hair-dye-related chemicals in guinea pigs. Contact Dermatitis 2000
May;42(5):270-275.
(5) Mathelier-Fusade P, Leynadier F. Crossreactions in contact dermatitis. Clin
Rev Allergy Immunol 1997 Winter;15(4):477-484.
(6): Goebel C, Troutman J, Hennen J, Rothe H, Schlatter H, Gerberick GF, et al.
Introduction of a methoxymethyl side chain into p-phenylediamine attenuates its
sensitizing potency and reduces the risk of allergy induction. Toxicol Appl
Pharmacol 2014 Feb 1;274(3):480-487.
(7) Blomeke B, Pot LM, Coenraads PJ, Hennen J, Kock M, Goebel C.
Cross-elicitation responses to 2-methoxymethyl-p-phenylediamine under hair dye
use conditions in p-phenylenediamine-allergic individuals. Br J Dermatol 2014
Sep 18.

Primary Objective: Pilot study to identify the optimal patch test concentration
for detecting contact allergy to ME-PPD in subjects with a proven contact
allergy to PPD, who may be allergic to ME-PPD.

Hypothesis:
In this study subjects will be tested to ME-PPD 0.5%, 1% and 2%, in white
petrolatum . We hypothesize that the optimal patch test concentration for
detecting contact allergy to ME-PPD will be 1%, comparable to the patch test
concentration of PPD.

Secondary Objective(s):
1. Investigate the clinical relevance of a positive diagnostic patch test
reaction to ME-PPD in subjects with a proven contact allergy to PPD, in
comparison to the (possible) allergic reactions as a result of an open use test
with ME-PPD 2%, PPD 2% and a control vehicle, respectively, with a
use-relevant exposure duration of 45 minutes.

2.As an independent control for cross-reactivity, we will investigate whether
subjects with a positive diagnostic patch test for ME-PPD, will show positive
patch test reactions to the acetylation products of PPD; MAPPD and DAPPD 1%, in
white petrolatum.

This is an observational pilot study with the use of epicutaneous patch-testing
and an open use test. Without the use of medicinal product non-blinded and
non-randomized in 44 PPD-positive subjects.

The duration for an individual participant is one week during which there will
be four visits of variable time durations.
Visit 1, day 0:
A short interview will be held to reconfirm basic information about the subject
and to check the inclusion and exclusion criteria. This visit also includes the
preparation of material, the application of the open use test on the volar side
of the forearms and the application of the patch test on the back. This visit
will take about 75 minutes. The actual patch test needs to be in situ for 48
hours.

Visit 2, day 2, 48 hours after application:
The visit will take about 15 minutes and includes removal of patch test,
reading of skin reactions according to guidelines of the International Contact
Dermatitis Research Group (ICDRG): - , +?, + , ++ , +++ or IR (irritation
response) and photographing.

Visit 3, day 3, 72 hours after application:
The visit will take about 15 minutes and includes reading and photographing of
the (possible) skin reactions at the sites of application.

Visit 4, day 7, 168 hours after application:
This visit includes the final reading and photographing of the (possible) skin
reaction at the sites of applications and will take about 15 minutes.

For the epicutaneous patch test and the open use test, four visits, divided
over 4 days will be planned. The first visit will take approximately 75 minutes
and the remaining visits will take 15 minutes each. There will be a
travelburden, but the particpants are offered the oppurtunity to perform the
reading at a place of their preference (at their home or at work for example).
During this study, subjects are asked to not wash or rub the test site or apply
(perfumed) lotion to the test areas.

Subjects are at risk for developing an allergic skin reaction on the test
sites, which can exist of redness, itch, vesicles and papules. This skin
reaction is self-limiting in nature, but can be treated with a local
corticosteroid cream if the reaction is inconvenient.

Participants will receive gift cards with a value of ¤100,- and reimbursement
of travel expenses.