“Hidradenitis suppurativa is difficult to cure and requires long-term treatment. As it is a rare disease, I think it is desirable to increase access to treatments with clear treatment benefits by providing both reimbursement and special calculation for this disease, which has a small number of patients.”

Hidradenitis suppurativa is a disease whose exact cause or pathogenesis has not yet been fully identified, and it is a rare disease with a prevalence rate of less than 1% in South Korea.

The number of patients with hidradenitis suppurativa in South Korea is estimated to be approximately 10,000 as of 2022, which only includes those who have been clearly diagnosed after experiencing recurrent lesions and formation of tracts beneath the skin.

Although TNF-α inhibitors are a reimbursable treatment option, options are limited when considering treatment failure and side effects.

At an interview with Dailypharm, Joo Yeon Ko, Professor of Dermatology at Hanyang University Medical Center emphasized the need to improve access by expanding treatment options for hidradenitis suppurativa.

Hidradenitis suppurativa causes abscesses to form in various areas around the sebaceous glands beneath the skin. Unlike typical abscesses, the lesions are connected to each other, forming channels known as “tracts.”

It is broadly classified into ▲active, where inflammation persists, and ▲inactive, where no further inflammation occurs; however, it is difficult to clearly distinguish between the active and inactive states.

Professor Ko explained, “Even in the same patient, the condition can be highly active at one time and stable at another, so the medication and treatment methods used may vary depending on the individual's condition. In the case of active disease, the patient experiences severe pain due to inflammation in areas such as the armpits, and the goal of treatment is to reduce the frequency of the inflammation.”

He continued, “Mild-to-moderate patients rarely visit university hospitals, and mild patients with symptoms in one or two areas are mainly treated at private clinics. It is important to identify the potential for progression to severe disease in mild patients, as a higher recurrence rate is associated with a higher risk of progression.”

Limited treatment options for suppurative hidradenitis, IL-17 emerges but faces hurdles for use

The basic treatment for suppurative hidradenitis is I&D (incision and drainage), which involves incising the area where the patient feels pain to remove the internal inflammation.

In addition, antibiotics are administered for about 3 months to reduce inflammation, and if there is a high risk of recurrence, sebum inhibitors used to treat acne are also used.

However, in severe cases, these treatments are not sufficient to control the inflammation, and biological agents are used. Currently, Humira (adalimumab), a TNF-α inhibitor, is covered by insurance.

In addition, although not yet covered by insurance, the interleukin-17 (IL-17) inhibitor Cosentyx (secukinumab) was approved in Korea in 2015, approximately 8 years after the approval of Humira.

Professor Ko said, “TNF-α inhibitors covered by insurance have the advantage of broadly blocking inflammation, but they also have the limitation of blocking the inflammatory response that is necessary for our bodies. IL-17 inhibitors have a more targeted mechanism than TNF-α inhibitors and show similar therapeutic effects and superior safety.”

According to overseas and domestic guidelines, both TNF-α inhibitors and IL-17 inhibitors are currently recommended as first-line treatment options. If sufficient therapeutic effects are not achieved with oral medications, one of the two approved biological agents can be selected.

Regarding this, Professor Ko explained, “Although TNF-α inhibitors have been covered by insurance in Korea for over 5 years, not many patients actually use them on-site. TNF-α inhibitors have a broad anti-inflammatory mechanism, which raises concerns about side effects, and when we explain this to patients, they are reluctant to use them.”

In actual treatment, patients who received IL-17 inhibitors (Cosentyx) showed a significant improvement in quality of life after continuing treatment for one and a half years, said Professor Ko. Previously, patients had severe symptoms requiring surgery and were unable to move their arms properly, but after treatment, their symptoms improved significantly, and the use of antibiotics and other medications decreased to 25% of the previous level.

Professor Ko stated, “In global clinical trials, approximately 60% of patients achieved HiSCR 50 with Cosentyx. This means that 60% of patients experienced a 50% or greater improvement in symptoms. While a 50% improvement may seem modest, it actually represents a significant improvement.”

He added, “Hidradenitis suppurativa is a disease that develops at a young age and requires long-term management, so controlling it with medications that have few side effects is the best approach. In this regard, I believe Cosentyx is a good option at this point.”

“Hidradenitis suppurativa, a rare and intractable disease pustular psoriasis…unrestricted special reimbursement calculation support is needed”

However, there are restrictions on the use of the IL-17 inhibitor Cosentyx. Unlike Humira, which is covered by reimbursement, Cosentyx is not yet covered.

In fact, Novartis Korea applied for reimbursement expansion for Cosentyx for hidradenitis suppurativa in November last year, but the discussions are at a standstill.

Professor Ko said, “IL-17 inhibitors have already been used extensively in psoriasis, so there is a tendency to prefer Cosentyx, but it is difficult to use it actively because it is not covered by insurance. Currently, if TNF-α inhibitors are used and sufficient effects are not seen, the cost of using Cosentyx thereafter is extremely high.”

Professor Ko emphasized that while it may be worth considering distinguishing treatment sequence within biological agents based on practical factors like drug prices, from a medical perspective, it is important to prioritize options that have fewer side effects.

He said, “If TNF-α inhibitors are used in the first line and are not effective, using Cosentyx as a the next treatment option can be an alternative, but this cannot be considered the ideal approach from a medical standpoint. In the long term, it would be desirable to apply reimbursement so that both treatments can be used on an equal footing.”

Additionally, Professor Ko stressed the need for policy support to apply special reimbursement calculation provisions for the rare and intractable disease suppurative hidradenitis.

Currently, suppurative hidradenitis is classified according to severity, and only severe cases are eligible for special reimbursement and insurance coverage, but the total number of patients is only about 10,000, and among them, less than 1,000 are estimated to be severe cases. Therefore, even if reimbursement and special calculations are applied simultaneously, it is unlikely to place a significant financial burden on the government.

Professor Ko said, “For diseases like hidradenitis suppurativa, which have a small number of patients and treatments offer clear benefits, it is necessary to increase access to treatment by providing both reimbursement and special calculations. Even if reimbursement and special calculations are applied simultaneously, only a few dozen patients will actually benefit and use Cosentyx each year.”

Finally, he added, “Effective medications for treating hidradenitis suppurativa are continuing to emerge, and better ones will be developed in the future. I hope patients do not lose hope and actively consult with medical professionals and seek treatment.”