Hemoglobin S Polymerization Inhibitor Drug Class List

Drugs in Drug Class: Hemoglobin S Polymerization Inhibitor

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Global Blood Theraps	OXBRYTA	voxelotor	TABLET;ORAL	213137-002	Oct 14, 2022		DISCN	Yes	No	10,493,035		Y
Global Blood Theraps	OXBRYTA	voxelotor	TABLET;ORAL	213137-001	Nov 25, 2019		DISCN	Yes	No
Global Blood Theraps	OXBRYTA	voxelotor	TABLET;ORAL	213137-001	Nov 25, 2019		DISCN	Yes	No	11,452,720
Global Blood Theraps	OXBRYTA	voxelotor	TABLET, FOR SUSPENSION;ORAL	216157-001	Dec 17, 2021		DISCN	Yes	No	9,018,210		Y	Y
Global Blood Theraps	OXBRYTA	voxelotor	TABLET;ORAL	213137-002	Oct 14, 2022		DISCN	Yes	No	9,018,210		Y	Y

Hemoglobin S Polymerization Inhibitor Market Analysis and Financial Projection

The hemoglobin S (HbS) polymerization inhibitor drug class represents a critical frontier in sickle cell disease (SCD) treatment, characterized by rapid innovation, shifting market dynamics, and complex intellectual property landscapes.

Market Dynamics

The global SCD treatment market is projected to grow at a 15.7% CAGR from 2024–2030, driven by increasing disease awareness and advancements in targeted therapies like HbS polymerization inhibitors[11]. Key developments include:

• Voxelotor (Oxbryta): Despite achieving accelerated FDA approval in 2019 for raising hemoglobin levels, it was withdrawn globally in 2024 after failing to demonstrate significant reduction in vaso-occlusive crises (VOCs)—a key efficacy metric[3][8].
• Emerging candidates: ILX-002, a novel oral inhibitor mimicking the Hb Stanleyville II variant, showed normalization of hemoglobin levels (≥13 g/dL) and reduced spleen weight by 41% in preclinical studies[1]. Pfizer’s GBT-601 (phase 2/3) and Afimmune’s Epeleuton (phase 2) aim to address voxelotor’s limitations with next-generation formulations[4][15].

Drug	Developer	Status	Key Differentiator
Voxelotor	Pfizer	Withdrawn (2024)	First-in-class; lacked VOC reduction
ILX-002	Illexcor	Preclinical	Mimics Hb Stanleyville II; functional cure potential
Epeleuton	Afimmune	Phase 2 (2025)	Broad patent coverage until 2040
GBT-601	Pfizer	Phase 2/3	Improved pharmacokinetics over voxelotor

---

Patent Landscape

HbS polymerization inhibitors face intense competition fueled by extended patent strategies:

1. Voxelotor: Primary patents expire in 2032, with secondary formulations and methods-of-use patents extending exclusivity to 2035–2037[8]. Its high-drug-load tablet patent (WO2022013187A1) further delays generics[5].
2. Epeleuton: Granted U.S. Patent 12,076,304 until 2040, covering compositions and treatment methods for SCD[4].
3. Masitinib: AB Science secured European patent protection until 2040 for SCD applications, despite being in early-phase trials[14].

Evergreening trends: Following Humira’s playbook[10], companies deploy patent thickets—Pfizer’s voxelotor has 132+ patents globally—to deter biosimilars. However, recent regulatory scrutiny (e.g., voxelotor’s withdrawal) underscores risks in relying on surrogate endpoints for accelerated approval[3][8].

---

Challenges and Opportunities

• Clinical efficacy: While voxelotor improved hemoglobin levels, its inability to reduce VOCs highlights the need for therapies targeting downstream consequences of HbS polymerization[3][16].
• Access barriers: In LMICs, where 75% of SCD cases occur, voxelotor’s exclusivity until 2032+ and lack of biowaivers complicate generics rollout[8].
• Pipeline diversity: CRISPR-based therapies (e.g., EDIT-301) and pyruvate kinase activators (mitapivat) compete with HbS inhibitors, creating a fragmented treatment landscape[6][17].

The HbS polymerization inhibitor sector remains pivotal, with ILX-002 and Epeleuton poised to redefine treatment paradigms if clinical trials validate their disease-modifying potential[1][4]. However, balancing IP strategies with robust clinical endpoints will be critical for sustained success.

“ILX-002 shows promise as a transformational oral therapy for SCD, potentially offering durable control of hemolysis and VOC prevention.” – Abdulmalik et al., Blood (2024)[1]

References

1. https://ashpublications.org/blood/article/144/Supplement%201/173/530653/A-Novel-Direct-Hemoglobin-S-Polymerization
2. https://patents.justia.com/patents-by-us-classification/514/815
3. https://www.medpagetoday.com/publichealthpolicy/productalert/112123
4. https://www.afimmune.com/2024/09/19/epeleuton-sickle-cell-disease-receives-key-us-patent-grant/
5. https://patents.google.com/patent/WO2022013187A1/en
6. https://www.delveinsight.com/blog/emerging-sickle-cell-disease-therapies
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC7810265/
8. https://medicinespatentpool.org/uploads/2023/09/MPP_Snapshots_2023_2024_RD_PDF_-Voxelotor.pdf
9. https://www.globenewswire.com/news-release/2025/01/13/3008371/14025/en/Arbutus-Provides-2025-Corporate-and-Financial-Update.html
10. https://dash.harvard.edu/server/api/core/bitstreams/0b2cd634-f60c-422f-8861-74725c0c940b/content
11. https://www.grandviewresearch.com/industry-analysis/sickle-cell-disease-treatment-market
12. https://www.globaldata.com/store/report/sickle-cell-disease-market-analysis/
13. https://investor.arbutusbio.com/news-releases/news-release-details/arbutus-provides-2025-corporate-and-financial-update
14. https://www.biospace.com/press-releases/ab-science-receives-notice-of-allowance-for-european-patent-covering-masitinib-until-2040-in-the-treatment-of-sickle-cell-disease
15. https://victoriacyanide.substack.com/p/gbt-601-hbs-polymerization-inhibitor
16. https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0291211
17. https://www.alliedmarketresearch.com/sickle-cell-disease-treatment-market-A31450
18. https://www.verifiedmarketresearch.com/product/hemoglobinopathies-market/