Application for salt-modified version of palbociclib filed in Korea

Salt-modified product successfully circumvented patent in April

Different formulation from Daewoong and Kwangdong, potentially avoiding first-generic exclusivity restrictions

Pfizer's breast cancer treatment ‘Ibrance Tab’

A salt-modified version of palbociclib (brand name: Ibrance), a breast cancer treatment, has been submitted for regulatory approval.

Generic versions of palbociclib are expected to enter the market in March 2027, when the original Ibrance substance patent expires. Daewoong Pharmaceutical and Kwangdong Pharmaceutical have already secured first generic exclusivity for products containing the same active ingredient and are preparing for launch.

Against this backdrop, a salt-modified palbociclib product has emerged as a new variable in the upcoming generic competition. The product is believed to have been developed by Boryung.

According to the Ministry of Food and Drug Safety (MFDS) on June 10, a tablet formulation containing palbociclib hemiadipate was submitted for approval on May 7.

The product is intended for the treatment of hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer.

Its approved indications are identical to those of the original Ibrance, including use in combination with an aromatase inhibitor as initial endocrine therapy in women and in combination with fulvestrant in women whose disease has progressed following endocrine therapy.

Ibrance is Pfizer's oral targeted therapy for breast cancer. The drug generated KRW 23 billion in outpatient prescriptions last year, according to UBIST data.

Domestic companies have long prepared for market entry upon expiration of Ibrance's substance patent by challenging patents and developing products. In addition to the substance patent, Ibrance’s formulation patents were invalidated through patent invalidation trials, while crystal-form patents were circumvented through product differentiation strategies.

In particular, Daewoong Pharmaceutical and Kwangdong Pharmaceutical satisfied the requirements for first generic approval and secured first generic exclusivity rights.

Daewoong's tablet product ‘Ranclib Tab’ and Kwangdong's capsule product ‘Alenci Cap’ obtained exclusive marketing rights from March 23, 2027, through December 22, 2027, the period immediately following expiration of the substance patent. During that period, other generic tablet and capsule formulations containing palbociclib cannot enter the market.

Boryung, which had also successfully challenged the patents, failed to obtain first generic approval. Industry observers believe the company adopted a strategy to launch the product early in the market by bypassing the patent through a salt-modified product strategy.

In December last year, Boryung challenged the crystal-form patent with a product based on ‘palbociclib hemiadipate crystalline particles,’ the same active ingredient used in the product for the current approval application. In April, the Intellectual Property Trial and Appeal Board ruled that the product did not fall within the scope of the patent claims.

Accordingly, if Boryung's product satisfies certain conditions, such as the initial filing of marketing authorization, it is expected that they will be able to overcome the market exclusivity barrier created by Daewoong and Kwangdong, and launch the product simultaneously when the substance patent expires next year.

Under Korea's Pharmaceutical Affairs Act, the sales injunction resulting from first generic exclusivity applies only to generics containing the same active ingredient. Since the 'hemiadipate' form applied for by Boryung differs chemically from the original 'base-free' (salt-free) form, it falls outside the scope of Daewoong and Kwangdong's exclusive rights for tablets and capsules. As a result, Boryung will be able to launch its product immediately following the expiration of the substance patent in March 2027."

Boryung has continued expanding investment in its oncology business while strengthening its breast cancer treatment portfolio.

The company already markets breast cancer therapies including ‘Xeloda’ and ‘Taxol,’ as well as ‘Samfenet,’ a biosimilar version of Herjuma developed by Samsung Bioepis. In 2024, the company also secured ‘Nerlynx Tab.’ through a co-promotion agreement with Bixink Therapeutics.

The company further completed preparations for palbociclib commercialization by obtaining reimbursement listing last year for Letrobo Tab, a letrozole product used in combination with palbociclib.

Meanwhile, both capsule and tablet formulations of Ibrance are currently reimbursed in Korea. Pfizer has introduced a tablet version that improves upon the food effect (which previously required administration immediately after a meal) of the existing capsule formulation.