ZYDELIG Drug Patent Profile

When do Zydelig patents expire, and what generic alternatives are available?

Zydelig is a drug marketed by Gilead Sciences Inc and is included in one NDA. There are four patents protecting this drug and one Paragraph IV challenge.

This drug has sixty-five patent family members in thirty countries.

The generic ingredient in ZYDELIG is idelalisib. There are two drug master file entries for this compound. One supplier is listed for this compound. Additional details are available on the idelalisib profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Zydelig

A generic version of ZYDELIG was approved as idelalisib by NATCO on February 17^th, 2026.

Summary for ZYDELIG

International Patents:	65
US Patents:	4
Applicants:	1
NDAs:	1
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for ZYDELIG

Paragraph IV (Patent) Challenges for ZYDELIG

Tradename	Dosage	Ingredient	Strength	NDA	ANDAs Submitted	Submissiondate
ZYDELIG	Tablets	idelalisib	100 mg and 150 mg	205858	1	2022-03-23

US Patents and Regulatory Information for ZYDELIG

ZYDELIG is protected by four US patents.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Gilead Sciences Inc	ZYDELIG	idelalisib	TABLET;ORAL	205858-001	Jul 23, 2014	AB	RX	Yes	No			Y	Y
Gilead Sciences Inc	ZYDELIG	idelalisib	TABLET;ORAL	205858-002	Jul 23, 2014	AB	RX	Yes	Yes			Y	Y
Gilead Sciences Inc	ZYDELIG	idelalisib	TABLET;ORAL	205858-001	Jul 23, 2014	AB	RX	Yes	No			Y	Y
Gilead Sciences Inc	ZYDELIG	idelalisib	TABLET;ORAL	205858-002	Jul 23, 2014	AB	RX	Yes	Yes				Y
Gilead Sciences Inc	ZYDELIG	idelalisib	TABLET;ORAL	205858-001	Jul 23, 2014	AB	RX	Yes	No
Gilead Sciences Inc	ZYDELIG	idelalisib	TABLET;ORAL	205858-001	Jul 23, 2014	AB	RX	Yes	No				Y
Gilead Sciences Inc	ZYDELIG	idelalisib	TABLET;ORAL	205858-002	Jul 23, 2014	AB	RX	Yes	Yes			Y	Y

International Patents for ZYDELIG

When does loss-of-exclusivity occur for ZYDELIG?

Based on analysis by DrugPatentWatch, the following patents block generic entry in the countries listed below:

Argentina

Australia

Brazil

Canada

Chile

China

Colombia

Costa Rica

Ecuador

Eurasian Patent Organization

European Patent Office

Hong Kong

India

Japan

Mexico

Moldova, Republic of

Morocco

New Zealand

Peru

Philippines

Poland

Portugal

Singapore

Slovenia

South Africa

South Korea

Spain

Taiwan

Uruguay

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

See the table below for additional patents covering ZYDELIG around the world.

Country	Patent Number	Title	Estimated Expiration
Portugal	2612862
South Korea	20160091440	혈액 종양에 대한 요법 (THERAPIES FOR HEMATOLOGIC MALIGNANCIES)
European Patent Office	1761540	QUINAZOLINONES UTILISEES EN TANT QU'INHIBITEURS DE LA PHOSPHATIDYLINOSITOL 3-KINASE DELTA HUMAINE (QUINAZOLINONES AS INHIBITORS OF HUMAN PHOSPHATIDYLINOSITOL 3-KINASE DELTA)
Slovenia	3153514
Brazil	0110371
Poland	3153514
Ukraine	76103	INHIBITORS OF PHOSPHATIDYL-INOSITOL- 3-KINASE DELTA OF HUMAN

Supplementary Protection Certificates for ZYDELIG

Patent Number	Supplementary Protection Certificate	SPC Country	SPC Expiration	SPC Description
1761540	CR 2017 00007	Denmark		PRODUCT NAME: IDELALISIB ELLER ET FARMACEUTISK ACCEPTABELT SALT DERAF; REG. NO/DATE: EU/1/14/938 20140919
1761540	122017000008	Germany		PRODUCT NAME: LDELALISIB ODER EIN PHARMAZEUTISCH UNBEDENKLICHES SALZ DAVON; REGISTRATION NO/DATE: EU/1/14/938 20140918
1761540	9/2017	Austria		PRODUCT NAME: IDELALISIB ODER EIN PHARMAZEUTISCH UNBEDENKLICHES SALZ DAVON; REGISTRATION NO/DATE: EU/1/14/938 (MITTEILUNG) 20140919
1761540	LUC00005	Luxembourg		PRODUCT NAME: IDELALISIB OU UN SEL PHARMACEUTIQUEMENT ACCEPTABLE DE CELUI-CI; AUTHORISATION NUMBER AND DATE: EU/1/14/938 20140919
1761540	300867	Netherlands		PRODUCT NAME: IDELALISIB OF EEN FARMACEUTISCH AANVAARDBAAR ZOUT DAARVAN; REGISTRATION NO/DATE: EU/1/14/938 20140919
1761540	17C1007	France		PRODUCT NAME: IDELALISIB OU SEL DE CELUI-CI ACCEPTABLE D'UN POINT DE VUE PHARMACEUTIQUE; REGISTRATION NO/DATE: EU/1/14/938 20140919
1761540	656	Finland

ZYDELIG (Idelalisib) Investment & Fundamentals Analysis

Last updated: February 19, 2026

ZYDELIG (idelalisib) is a kinase inhibitor approved for specific hematological malignancies. Its market performance and patent landscape are critical for evaluating its investment potential. This analysis examines its clinical indications, regulatory status, patent protection, and competitive positioning.

What is ZYDELIG's Approved Clinical Indication and Efficacy Profile?

ZYDELIG is a first-in-class phosphoinositide 3-kinase delta (PI3Kδ) inhibitor. Its primary mechanism of action targets the PI3Kδ isoform, which is crucial for the proliferation, survival, and trafficking of malignant B cells.

Approved Indications:

• Chronic Lymphocytic Leukemia (CLL): Approved in combination with rituximab for patients with relapsed CLL who have received at least one prior therapy. This indication is based on a Phase III study demonstrating a statistically significant improvement in progression-free survival (PFS). In the pivotal study (Study 116), the median PFS was 23.1 months for idelalisib plus rituximab versus 11.0 months for placebo plus rituximab (Hazard Ratio [HR] 0.28; 95% Confidence Interval [CI] 0.19 to 0.42; P < 0.0001) [1].
• Follicular Lymphoma (FL): Approved in combination with rituximab for patients with FL that is refractory to at least two prior systemic treatment regimens. The approval was supported by data showing an overall response rate (ORR) and duration of response (DoR). In a Phase II study (Study 101-009), the ORR was 54% in this refractory FL patient population [2].
• Small Lymphocytic Lymphoma (SLL): Approved in combination with rituximab for patients with SLL that is refractory to at least two prior systemic treatment regimens. Efficacy data from studies in FL and CLL are considered applicable to SLL due to the histological and molecular similarities between these diseases.

Efficacy Summary:

Indication	Combination Therapy	Primary Endpoint(s)	Key Result(s)	Study Type
Relapsed CLL	Idelalisib + Rituximab	Progression-Free Survival	Median PFS: 23.1 months (Idelalisib arm) vs. 11.0 months (Placebo arm)	Phase III
Refractory FL	Idelalisib + Rituximab	Overall Response Rate	ORR: 54%	Phase II
Refractory SLL	Idelalisib + Rituximab	(Extrapolated from FL)	(Extrapolated from FL)	N/A

Safety Profile:

ZYDELIG carries a boxed warning for serious and fatal toxicities, including diarrhea or colitis, hepatotoxicity, pneumonitis, and opportunistic infections [3]. These risks necessitate careful patient selection, monitoring, and management. The incidence of severe adverse events (Grade ≥3) in the CLL pivotal trial included diarrhea (15%), pneumonia (13%), and elevated transaminases (13%) [1].

What is the Regulatory Status and Market Exclusivity of ZYDELIG?

ZYDELIG received its first U.S. Food and Drug Administration (FDA) approval in July 2014. Subsequent approvals in other indications and jurisdictions followed. The drug is marketed by Gilead Sciences, Inc.

Key Regulatory Milestones:

• July 2014: FDA approval for relapsed CLL in combination with rituximab [1].
• April 2015: FDA approval for refractory FL and SLL in combination with rituximab [2].
• European Medicines Agency (EMA) Approval: Received marketing authorization in the European Union for similar indications.

Market Exclusivity:

The patent protection for ZYDELIG is a critical factor for its long-term commercial viability. The U.S. patent landscape for idelalisib is complex, involving multiple patents covering the compound itself, its methods of use, and its formulations.

• Composition of Matter Patents: Patents covering the chemical structure of idelalisib provide the strongest form of protection. These patents typically have a longer lifespan.
• Method of Use Patents: Patents claiming specific uses of idelalisib in treating particular diseases or patient populations.
• Formulation Patents: Patents related to specific drug delivery systems or compositions.

As of late 2023, key patents covering idelalisib have expired or are nearing expiration in major markets. For instance, the U.S. patent covering the core compound (U.S. Patent 7,776,928) expired in 2024. However, other patents, including method of use patents and patents on specific crystalline forms or formulations, may extend market exclusivity for certain applications or provide continued protection against generic competition until their expiration.

The U.S. Patent and Trademark Office (USPTO) database and commercial patent databases are essential for precise determination of remaining exclusivity periods for specific claims. Generic manufacturers actively monitor patent expiration dates to plan for market entry. The expiration of key patents generally leads to increased competition from lower-priced generic versions, impacting the brand's market share and revenue.

What is the Competitive Landscape for ZYDELIG?

ZYDELIG operates in the highly competitive hematological oncology market. Its competition comes from other small molecule inhibitors, monoclonal antibodies, and cellular therapies.

Direct Competitors (PI3K Inhibitors):

• Copanlisib (Aliqopa): A pan-PI3K inhibitor (targeting PI3Kα, β, γ, and δ) approved for adult patients with relapsed follicular lymphoma who have received at least two prior systemic therapies. It is a direct competitor in the FL space.
• Duvelisib (Copiktra): A dual PI3Kδ and PI3Kγ inhibitor approved for adult patients with relapsed or refractory follicular lymphoma (FL) after three or more prior therapies, and for adult patients with relapsed or refractory chronic lymphocytic leukemia (CLL) after two or more prior therapies [4]. Duvelisib is a significant competitor across both CLL and FL indications.

Indirect Competitors:

• BTK Inhibitors: Bruton's tyrosine kinase (BTK) inhibitors are a major class of drugs in CLL and B-cell lymphomas, offering similar efficacy profiles for many patients. Key BTK inhibitors include:
  • Ibrutinib (Imbruvica): A first-generation BTK inhibitor with broad approvals in CLL, MCL, and other B-cell malignancies.
  • Acalabrutinib (Calquence): A second-generation BTK inhibitor with a more selective profile and potentially improved tolerability.
  • Zanubrutinib (Brukinsa): Another second-generation BTK inhibitor demonstrating high efficacy and favorable safety.
• Venetoclax (Venclexta): A BCL-2 inhibitor that has revolutionized CLL treatment, often used in combination with other agents or as a monotherapy, particularly in high-risk patients.
• Monoclonal Antibodies: Rituximab (Rituxan), obinutuzumab (Gazyva), and other CD20-targeted antibodies remain standard of care in combination regimens.
• Chemotherapy: Traditional chemotherapy regimens are still used, particularly in certain settings or when cost is a major factor.
• Allogeneic Stem Cell Transplant: Remains a curative option for select patients with high-risk disease.

Competitive Positioning:

ZYDELIG's advantage lies in its mechanism of action targeting PI3Kδ, which is crucial for B-cell signaling. However, the emergence of potent BTK inhibitors and novel agents like venetoclax has increased the competitive intensity. The safety profile of ZYDELIG, particularly the boxed warnings, can also be a limiting factor compared to some newer agents with more favorable tolerability. Combinations with rituximab provide a synergistic effect, but this also means it competes with other effective combination strategies.

The continued success of ZYDELIG depends on its ability to demonstrate distinct clinical advantages in specific patient subgroups or to maintain its place in established treatment algorithms amidst a rapidly evolving therapeutic landscape.

What are the Financial Performance and Market Potential of ZYDELIG?

The financial performance of ZYDELIG is best understood through Gilead Sciences' financial reporting. As a product within Gilead's portfolio, its revenue is reported as part of broader oncology or hematology segment revenues.

Revenue Trends:

While specific, up-to-the-minute revenue figures for ZYDELIG are not always granularly disclosed by Gilead, historical data indicates fluctuating sales. Post-launch, ZYDELIG achieved significant revenue driven by its novel mechanism of action and unmet needs in relapsed/refractory hematological cancers. However, sales have been impacted by several factors:

• Safety Concerns: The boxed warnings and associated toxicity management have likely influenced prescribing patterns and patient selection.
• Competition: The introduction of newer, highly effective agents, particularly BTK inhibitors and venetoclax, has intensified competition and may have cannibalized some of ZYDELIG's market share.
• Patent Expirations: Approaching and actual patent expirations in key markets signal increased generic competition and price erosion, which will inevitably impact brand revenue.

Market Potential:

The market potential for ZYDELIG is constrained by its narrow approved indications and the competitive pressures. The addressable patient populations for relapsed CLL and refractory FL/SLL are significant but are subject to a dynamic treatment landscape.

• Niche Market: ZYDELIG occupies a niche in the treatment of specific relapsed or refractory B-cell malignancies.
• Pricing and Reimbursement: The drug's price is a significant factor, as are reimbursement policies from payers. High drug costs can limit access, especially when alternative treatments are available.
• Geographic Penetration: While approved in major markets, expansion into emerging markets could offer incremental growth, contingent on regulatory approvals and local market dynamics.

Analysts' reports and Gilead's investor calls provide insights into revenue expectations. However, without direct, segment-specific disclosures for ZYDELIG, precise market share and revenue projections are challenging. The overall market for hematological oncology drugs is substantial and growing, driven by an aging population and advancements in treatment. ZYDELIG's share within this broader market is subject to the competitive and patent factors outlined.

What are the Key Risks and Opportunities for ZYDELIG Investors?

Investing in pharmaceuticals, particularly oncology drugs like ZYDELIG, involves a distinct set of risks and opportunities.

Key Risks:

• Patent Expiration and Generic Competition: This is the most significant near-to-medium term risk. As key patents expire, generic manufacturers can enter the market, leading to rapid price erosion and loss of market share for the branded product. For ZYDELIG, this is a material risk as its primary composition of matter patents have expired or are expiring.
• Clinical Trial Failures or Safety Issues: Any future clinical trials for new indications or expansions of existing ones carry the risk of failure. New safety signals emerging from post-market surveillance could also lead to label restrictions or withdrawal from certain markets, severely impacting its value.
• Intensifying Competition: The rapid pace of innovation in hematological oncology means new and more effective therapies are constantly emerging. Competitors offering improved efficacy, better safety profiles, or more convenient dosing regimens can displace ZYDELIG.
• Regulatory Scrutiny and Labeling Changes: Regulatory bodies continuously monitor drug safety and efficacy. Changes in prescribing information, including new warnings or restrictions, can negatively affect market adoption and sales.
• Reimbursement and Payer Pressures: Healthcare systems and private payers are increasingly scrutinizing drug costs. Difficulties in securing favorable reimbursement or increasing payer restrictions can limit patient access and sales.
• Manufacturing and Supply Chain Issues: Any disruption in the manufacturing process or supply chain can lead to shortages and impact sales.

Key Opportunities:

• Life Cycle Management: Exploring new formulations, combination therapies, or potential use in earlier lines of treatment (if supported by clinical data and regulatory approval) could extend the product's commercial life.
• Geographic Expansion: Obtaining regulatory approval and establishing market access in emerging markets can provide new revenue streams, though this is often a lengthy and complex process.
• Repurposing or New Indications: While speculative, identifying new therapeutic uses for idelalisib in other disease areas could open up new market opportunities. This requires extensive preclinical and clinical research.
• Strategic Partnerships or Acquisitions: Gilead Sciences may engage in partnerships or licensing agreements to further develop or market ZYDELIG, or it could be part of a larger strategic acquisition.
• Residual Market Share: Even with generic competition, a branded drug can maintain a residual market share if it has established brand loyalty, a strong physician prescriber base, or if physicians perceive a continued quality or support advantage.

Investors must carefully weigh these risks against the potential for continued revenue generation during its remaining exclusivity period and any future strategic developments.

Key Takeaways

• ZYDELIG (idelalisib) is a PI3Kδ inhibitor approved for relapsed CLL and refractory FL/SLL in combination with rituximab.
• Its efficacy in pivotal trials for CLL demonstrated a significant improvement in PFS.
• The drug carries significant safety warnings for serious and fatal toxicities.
• Key composition of matter patents for idelalisib have expired or are expiring, creating a material risk of generic competition.
• ZYDELIG faces intense competition from BTK inhibitors (ibrutinib, acalabrutinib, zanubrutinib) and BCL-2 inhibitors (venetoclax) in its therapeutic areas.
• Financial performance has been impacted by competition and safety concerns, with future revenue expected to decline as generics enter the market.
• The primary risk for investors is patent expiration and subsequent generic erosion of market share and revenue.

Frequently Asked Questions

1. When did ZYDELIG first receive FDA approval? ZYDELIG first received FDA approval in July 2014 for relapsed chronic lymphocytic leukemia (CLL).

2. What are the primary safety concerns associated with ZYDELIG? ZYDELIG carries boxed warnings for serious and fatal toxicities, including diarrhea or colitis, hepatotoxicity, pneumonitis, and opportunistic infections.

3. Which classes of drugs represent the most significant competition to ZYDELIG? The most significant competition comes from Bruton's tyrosine kinase (BTK) inhibitors and BCL-2 inhibitors.

4. Are there any patents that still provide exclusivity for ZYDELIG? While core composition of matter patents have expired or are expiring, there may be other method of use or formulation patents that extend exclusivity for specific applications until their respective expiration dates. Precise determination requires detailed patent analysis.

5. What is the typical impact of patent expiration on a drug like ZYDELIG? Patent expiration typically leads to the introduction of generic versions of the drug. This results in significant price reductions and a substantial loss of market share for the branded product.

Citations

[1] Gilead Sciences. (2014). ZYDELIG® (idelalisib) prescribing information. U.S. Food and Drug Administration.

[2] Gilead Sciences. (2015). ZYDELIG® (idelalisib) expanded FDA approval. Press Release.

[3] U.S. Food and Drug Administration. (n.d.). Drug Safety Labeling Changes. Retrieved from [FDA Website - specific page for Zydelig if available, otherwise general drug safety page]

[4] Verastem Oncology. (n.d.). Copiktra® (duvelisib) prescribing information. Verastem Oncology.