PharmaEssentia Wins Fifth ET Approval While Merck Awaits Phase 3 Data

400,000.

That is China's estimated count of people with essential thrombocythemia (ET). On October 15, Taiwan's PharmaEssentia said China had approved its long-acting interferon BESREMi (ropeginterferon alfa-2b) for ET, a blood cancer in which the bone marrow makes too many platelets. Counting from Taiwan in May, it is BESREMi's fifth ET approval in five months.

In the same disease, Merck's oral drug bomedemstat, which Merck acquired by buying Imago BioSciences for about $1.35 billion, is still in Phase 3. Incyte's antibody INCA033989 started enrolling its Phase 3 trial only in September.

Our view: in ET, PharmaEssentia's lead is time. The China approval opens the largest patient pool among its five markets, but only for second-line use, so the 400,000 headline shrinks once the label is applied.

01 | Five ET Approvals in Five Months

ET belongs to the myeloproliferative neoplasms (MPNs), the same family as polycythemia vera (PV), the disease BESREMi was first approved for. Patients' main risks are blood clots and bleeding.

BESREMi's 2026 ET approvals, as disclosed in PharmaEssentia's Taiwan stock exchange filings:

1. Taiwan: approval letter on May 12, for adults resistant or intolerant to hydroxyurea
2. Macau: import pre-authorization for the new ET indication, announced August 2
3. Japan: approval announced August 24
4. United States: FDA approval on August 28 for all adults with ET, regardless of prior treatment
5. China: NMPA approval on October 13 (certificate received October 15), for adults with an inadequate response to hydroxyurea

Its Singapore subsidiary announced a filing with Singapore's Health Sciences Authority on October 12 to add ET, and on August 14 PharmaEssentia asked Taiwan's FDA to widen the Taiwan label to all adult ET patients.

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Figure 1 | Macau's is an import pre-authorization; the Macau and Japan dates are announcement dates.

02 | Side by Side: Where ET Treatments Stand

Merck's two Phase 3 trials are no longer recruiting. Shorespan-007 compares bomedemstat with hydroxyurea in about 300 patients who have never received cytoreductive therapy; Shorespan-006 compares it with best available therapy in about 340 patients who are resistant to or intolerant of hydroxyurea. ClinicalTrials.gov lists estimated primary completion on July 14, 2027 for Shorespan-006 and September 28, 2027 for Shorespan-007. No Phase 3 data have been published.

Incyte has the most striking early numbers. At EHA in June, 70% of 114 ET patients (80 people) across two Phase 1 studies reached a complete hematologic response, and the FDA granted Breakthrough Therapy designation in November 2025. Those are single-arm Phase 1 data. BESREMi's randomized Phase 3 SURPASS-ET compared it with anagrelide in 174 patients who were resistant to or intolerant of hydroxyurea: 43% versus 6% kept a response at both month 9 and month 12. The two studies differ in design and endpoints, so their numbers cannot be ranked against each other. INCA033989 also targets only CALR-mutant patients, roughly 20% to 30% of ET, and its Phase 3 EXCALIBUR-ET2 lists an estimated primary completion date of June 2029.

When BESREMi won US approval in August, Merck's earliest Phase 3 primary completion was still almost a year away and Incyte's almost three years away, and both would still need filing and review after that. That gap is PharmaEssentia's head start in ET.

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Figure 2 | Old drugs lower platelet counts; Merck's and Incyte's candidates are still in Phase 3; BESREMi is approved in five markets.

03 | Discounting China's 400,000 Patients Twice

The first discount is the label. China approved BESREMi for adults with an inadequate response to hydroxyurea, which makes it a second-line drug there, while the US label covers all adults. In China, patients must try hydroxyurea first, and anagrelide already sits in the second-line slot. Merck's Shorespan-006 and Incyte's EXCALIBUR-ET2 are aimed at the same line.

How many patients does that leave? A 2014 review in Leukemia & Lymphoma estimated that about 20% to 25% of PV and ET patients treated with hydroxyurea become resistant or intolerant. Even if all 400,000 had taken hydroxyurea, the label's reach would be capped at roughly 80,000 to 100,000 people.

The second discount is precedent. BESREMi was approved for second-line PV in China in June 2024. PharmaEssentia's revenue rose 83.5% in the first nine months of 2026, and the company attributed the growth mainly to its US subsidiary, PharmaEssentia USA, without mentioning China.

What China does give PharmaEssentia is entry. The company says BESREMi is the only interferon formally approved by the NMPA for ET, and that it has launched ET sales and marketing in China. How much it sells will depend on how quickly it can move beyond second line.

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Figure 3 | China has the most patients, but the label stops at second line; at 20%–25%, the reachable pool is at most 80,000–100,000.

04 | The Numbers to Watch

1. NT$2.64 billion: September revenue, up 99.98% year on year but only 0.69% above August. The US ET approval came on August 28, and September, the first full month after it, shows little sign of ET sales. Revenue for the first nine months was NT$19.74 billion, up 83.5%.
2. 2027: the year Merck's two Phase 3 trials are expected to reach primary completion. Until then, neither Merck nor Incyte has Phase 3 data in ET.
3. 4,500: ET patients in Taiwan. Taiwan's May label, like China's, is limited to second line; PharmaEssentia has asked for it to be widened to all adults.

The next signal comes by November 10, when Taiwan-listed companies must report October revenue, the second full month after the US ET approval.

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Figure 4 | September revenue roughly doubled year on year but rose only 0.69% from August.

Conclusion | Five Approvals Buy Time

In five months and five markets, PharmaEssentia has rerun its PV playbook in ET, this time ahead of Merck and Incyte. China opens the biggest patient pool, but only at second line, with a rough ceiling of 80,000 to 100,000 people. Two things to watch: October revenue, due by November 10, for signs of US ET sales; and when the Taiwan and China labels move toward first line.

This article is an analysis of the industry and company. It does not constitute investment or medical advice.

References

1. PharmaEssentia | Material information: BESREMi approved by China's NMPA for adult ET (in Chinese) | 2026-10-15 | https://mops.twse.com.tw/mops/#/web/t05st01
2. PharmaEssentia | Material information: BESREMi approved by the US FDA for adult ET (in Chinese) | 2026-08-29 | https://mops.twse.com.tw/mops/#/web/t05st01
3. PharmaEssentia | Material information: application to Taiwan FDA to widen the ET indication; Taiwan approval letter (2026-05-12); Macau (2026-08-02); Japan (2026-08-24); Singapore filing (2026-10-12) (in Chinese) | https://mops.twse.com.tw/mops/#/web/t05st01
4. Taiwan Stock Exchange OpenAPI | Monthly revenue of listed companies (PharmaEssentia 6446, September 2026) | 2026-10-15 | https://openapi.twse.com.tw/v1/opendata/t187ap05_L
5. Merck | Merck Announces Phase 3 Trial Initiation for Bomedemstat for the Treatment of Certain Patients With Essential Thrombocythemia | 2024-08-27 | https://www.merck.com/news/merck-announces-phase-3-trial-initiation-for-bomedemstat-an-investigational-candidate-for-the-treatment-of-certain-patients-with-essential-thrombocythemia/
6. BioPharma Dive | Merck to acquire Imago BioSciences for $1.35B | 2022-11-21 | https://www.biopharmadive.com/news/merck-imago-acquire-deal-bone-marrow-cancer/637054/
7. ClinicalTrials.gov | Shorespan-007 (NCT06456346), Shorespan-006 (NCT06079879), EXCALIBUR-ET2 (NCT07623200) | accessed 2026-10-16 | https://clinicaltrials.gov/study/NCT06456346 ; https://clinicaltrials.gov/study/NCT06079879 ; https://clinicaltrials.gov/study/NCT07623200
8. Incyte | Incyte Announces New Positive Data at EHA 2026 Showed INCA033989 Achieved Rapid Robust and Sustained Clinical and Molecular Responses and Was Well Tolerated in Patients with Myelofibrosis and Essential Thrombocythemia | 2026-06-13 | https://investor.incyte.com/news-releases/news-release-details/incyte-announces-new-positive-data-eha-2026-showed-inca033989
9. BioPharm International | FDA Approves Ropeginterferon Alfa-2b-njft (Besremi) for Essential Thrombocythemia (SURPASS-ET results) | 2026-08-31 | https://www.biopharminternational.com/view/fda-approves-ropeginterferon-alfa-2b-njft-besremi-essential-thrombocythemia
10. Sever M, Newberry KJ, Verstovsek S | Therapeutic options for patients with polycythemia vera and essential thrombocythemia refractory/resistant to hydroxyurea | Leukemia & Lymphoma | 2014 | https://pmc.ncbi.nlm.nih.gov/articles/PMC4835800
11. Klampfl T, et al. | Somatic Mutations of Calreticulin in Myeloproliferative Neoplasms | New England Journal of Medicine | 2013 | https://doi.org/10.1056/NEJMoa1311347