Long-term efficacy and safety of microwave ablation in the treatment of mild axillary hidradenitis suppurativa: a randomized intra-patient controlled trial

Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disease of the
hair follicle, and is predominantly located in the axillary, inguinal and
anogenital regions. Current treatment options for HS include systemic
antibiotics, anti-TNF*, and surgery, which are used to treat the consequences
rather than treating the primary pathogenesis of HS. With microwave ablation
(MWA), using the heat generated from electromagnetic waves in the microwave
energy spectrum, hair follicles and apocrine and eccrine glands in the
(hypo)dermis are ablated through thermolysis. MWA was recently approved for the
treatment of axillary hyperhidrosis (miraDry) and removal of axillary hair
(miraSmooth). We hypothesize a beneficial and long-term (prophylactic) effect
of MWA in HS patients.

Primary objective:
To prospectively evaluate the lesion (AN-)count, i.e. abscesses, inflammatory
nodules, and draining sinuses, in the axilla treated with MWA compared to the
untreated contralateral axilla after six months.

Secondary objectives:
- To prospectively evaluate the AN-count in the axilla treated with MWA at
month six relative to baseline.
- To prospectively evaluate the AN-count in the axilla treated with MWA at
month three compared to the untreated contralateral axilla, i.e. early response.
- To prospectively assess the effect of MWA on the number of HS flares in the
treated and untreated axillae.
- To evaluate patient-reported outcome measures (PROMs).
- To assess the average number of hair containing follicles in the treated area
at month six relative to baseline.
- To assess the decrease of sweat production in the treated area at month six
relative to baseline.
- To prospectively assess the safety and tolerability two weeks, three months,
six months after treatment with MWA.
- Optional (separate consent): assessment of long-term efficacy and safety at
month 12 and 36 after MWA treatment.

Randomized intra-patient controlled trial.

Twenty patients will be randomly allocated to a one-sided single MWA treatment
in one axillary region with a miraDry device.

Eligible patients will be recruited during routine clinical care in the
department of Dermatology of the Erasmus MC and Havenziekenhuis. The study will
be performed in the Erasmus MC. There is a total of 3 visits and an optional 2
visits which are incorporated in routine clinical care. Per subject a total
number of 3 physical examinations and 3 starch-iodine tests will be performed.
In addition, two tattoo ink spots (1 mm) will be placed in both axillary
regions at baseline to assure identical measuring areas during the treatment
and follow-up period. The ink spots will be removed by laser therapy at the end
of the study. During the follow-up of 6 months participants will be asked to
count the number of flares and the use of topical clindamycin 1% in a diary,
and to take (self)photographs of the lesions.