Mechanism of Action: Breast Cancer Resistance Protein Inhibitors

Drugs with Mechanism of Action: Breast Cancer Resistance Protein Inhibitors

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Sentynl Theraps Inc	ZOKINVY	lonafarnib	CAPSULE;ORAL	213969-002	Nov 20, 2020		RX	Yes	Yes	7,838,531
Sentynl Theraps Inc	ZOKINVY	lonafarnib	CAPSULE;ORAL	213969-002	Nov 20, 2020		RX	Yes	Yes
Sentynl Theraps Inc	ZOKINVY	lonafarnib	CAPSULE;ORAL	213969-001	Nov 20, 2020		RX	Yes	No	7,838,531
Sentynl Theraps Inc	ZOKINVY	lonafarnib	CAPSULE;ORAL	213969-001	Nov 20, 2020		RX	Yes	No
Msd Sub Merck	ZEPATIER	elbasvir; grazoprevir	TABLET;ORAL	208261-001	Jan 28, 2016		DISCN	Yes	No	8,871,759		Y	Y
Msd Sub Merck	ZEPATIER	elbasvir; grazoprevir	TABLET;ORAL	208261-001	Jan 28, 2016		DISCN	Yes	No	7,973,040		Y	Y

Market dynamics and patent landscape for Breast Cancer Resistance Protein (BCRP) inhibitors

Last updated: April 23, 2026

BCRP inhibitors are positioned as permeability and resistance modulators across oncology, with patent activity concentrated in (i) BCRP-selective small molecules, (ii) combination regimens where BCRP inhibition is part of broader efficacy claims, and (iii) antibody or dual-target approaches in which BCRP is targeted directly or functionally. The core market dynamic is that BCRP is an efflux transporter that can reduce intracellular exposure of cytotoxics and targeted agents; commercial traction hinges on demonstrating clinically meaningful exposure or response improvements in specific BCRP-high tumors or treatment lines, not on transporter inhibition alone.

What is the market dynamic for BCRP inhibitors in oncology?

BCRP (ABCG2) limits drug accumulation through ATP-binding cassette efflux. In breast cancer and other solid tumors, ABCG2 upregulation is linked to reduced sensitivity to chemotherapy and to a subset of multidrug resistance. The commercial rationale for BCRP inhibitors is exposure restoration: inhibitors can increase intracellular concentrations of co-administered substrates, potentially improving response rates, progression-free survival (PFS), or overcoming resistance.

Demand drivers

• Predictive positioning by transporter expression and resistance phenotype. Developers target settings where ABCG2 is elevated or where resistance is suspected to be transporter-mediated.
• Co-formulation/co-administration logic. Most BCRP inhibitor programs are designed to be used with cytotoxics (and sometimes targeted agents) that are known BCRP substrates, making companion strategy and trial design central to adoption.
• Safety and tolerability constraints. BCRP also contributes to normal tissue drug disposition. Clinical differentiation depends on achieving a meaningful inhibition window without unacceptable pharmacokinetic (PK) interactions, gastrointestinal toxicity, or myelosuppression augmentation.

Competitive structure

The landscape divides into:

• Direct BCRP inhibitors (small molecules, often optimized for potency/selectivity).
• Dual-function or multi-pathway strategies where BCRP inhibition is one component of broader pharmacology.
• Combination regimens with standard-of-care drugs where the BCRP inhibitor is the differentiating clinical variable.

Adoption bottleneck

The adoption barrier is not biological plausibility; it is proof. Market pull requires:

• Clear evidence the BCRP inhibitor improves clinical outcomes (not only PK).
• Manageable safety when used with BCRP substrate drugs.
• Robust evidence supporting which patient populations benefit.

Which BCRP inhibitors define the patent landscape?

BCRP inhibitors have historically included third-generation tyrosine kinase inhibitors and pharmacologic modulators used off-label or as research tools, but the modern patent landscape is dominated by proprietary small-molecule BCRP inhibitors and improved analogs. Patent families generally attempt to cover: 1) chemical entities (composition-of-matter), 2) formulations, 3) therapeutic methods (treating cancers with BCRP substrate co-therapy), 4) patient selection (biomarkers such as ABCG2 expression or transporter activity).

Patent strategy patterns in BCRP portfolios

• Composition-of-matter broad coverage around scaffold families, often with extensive analog claim sets.
• Use claims tied to BCRP substrate co-administered drugs. Many method claims are drafted so that clinical utility is defined by inhibition plus the substrate.
• Combination claims with chemotherapy backbones. Claims often list one or more substrate classes (topoisomerase inhibitors, taxanes, anthracyclines, kinase inhibitors) rather than limiting to a single drug.

Where is the “real” enforcement risk: composition-of-matter vs. method/combination claims?

For investors and partners, enforcement risk typically concentrates in two layers:

1) Composition-of-matter (entity) claims

• These are the strongest for exclusivity because they block manufacture and sale of the defined molecules.
• For BCRP inhibitors, many families are scaffold-based, meaning design-around is difficult once key potency and selectivity relationships are locked into the core claims.

2) Method claims and combination regimens

• Enforcement can be more fact-intensive because it depends on clinical use and dosing logic (co-administration).
• However, method claims can still be strong if they are drafted to require BCRP inhibition with specific co-administered substrate categories and dosing schedules.

Practical conclusion for development

Most commercial viability depends on avoiding infringement of the most defensible combination and entity families. Even if entity claims are designed around, method claims remain a risk if trials use similar co-therapy, dosing, or patient selection.

How do BCRP inhibitors compete: what differentiates programs?

Differentiators that show up in patent and clinical positioning

• BCRP potency and selectivity (cellular efflux assays, transporter selectivity profiles).
• Reversibility and duration of inhibition (how sustained inhibition is across dosing intervals).
• Drug-drug interaction (DDI) management by controlling exposure and minimizing off-target transporter inhibition.
• Therapeutic index when combined with BCRP substrate agents.
• Biomarker strategy tied to ABCG2 expression, functional assays, or transcriptomic signatures.

Typical market messaging in this space

Programs are marketed around “resistance reversal” or “improved intracellular exposure,” but patents translate those concepts into:

• specific co-administered BCRP substrates,
• clinical contexts (e.g., metastatic disease, refractory lines),
• dosing and schedule claims.

What does timing look like: patent term, continuations, and freedom-to-operate?

BCRP inhibitor portfolios often use continuation strategies to extend protection around:

• new analogs,
• improved formulations,
• additional therapeutic indications,
• refined biomarker-defined patient groups.

The practical timeline is driven by:

• priority date and first filing,
• continuation chain breadth,
• potential patent term adjustments (PTA) and patent term extensions (PTE) where applicable,
• regulatory exclusivity interacting with patent life.

A commercial program must map:

• which families still have live claims in key geographies (US, EP, CN, JP),
• whether claims target the exact scaffold or only narrower analog sets,
• whether there are blocking method/combination claims.

What is the current patent landscape shape for BCRP inhibitors?

The landscape is concentrated around:

• Small-molecule BCRP inhibitors with proprietary scaffolds,
• Second-generation analog series designed to improve potency and systemic exposure,
• Combination and method claims that define clinical use with BCRP substrates.

The biggest competitive pressure points are:

• overlapping chemical space among later filings,
• shared co-therapy regimens (common chemotherapy backbones and known BCRP substrate classes),
• repeated biomarker hypotheses around ABCG2 expression and transporter functional activity.

What actionable market conclusions follow from the patent dynamics?

For R&D strategy

• Prioritize BCRP-selective candidates with a clear patent moat around composition-of-matter and at least one enforceable method claim tied to a defined clinical regimen.
• Design trials to strengthen method-of-use defensibility: transporter-expression stratification and co-therapy exposure endpoints help align clinical claims with patent theory.
• Build DDI and tolerability evidence early because the ability to dose BCRP substrates is the difference between “works in vitro” and “adopted in practice.”

For investment diligence

• Treat freedom-to-operate as a combination problem, not just a molecule problem. Even if a candidate is entity-safe, method claims can create read-across risk if the co-therapy is inside a covered regimen.
• Focus on claim survivability. The question is which claims are likely to remain in force across major jurisdictions at trial readouts, not which claims exist on day one.
• Track continuation families. BCRP inhibitors frequently show long claim tail behavior due to continuation practice.

Key regulatory and scientific anchor points

• BCRP is ATP-dependent and is encoded by ABCG2, functioning as an efflux transporter linked to multidrug resistance mechanisms in cancer. [1]
• BCRP inhibition has been studied as a way to modulate the pharmacokinetics and efficacy of co-administered substrate drugs in multidrug resistance contexts. [1-3]

Key Takeaways

• The market for BCRP inhibitors is built around restoring intracellular exposure of BCRP substrate drugs in transporter-driven resistance settings.
• Patent leverage is typically strongest for composition-of-matter and secondarily for method/combination claims that tie inhibition to co-administration schedules and substrate drugs.
• Commercial success depends on clinical proof that BCRP inhibition improves outcomes with manageable safety and predictable DDI behavior.
• Diligence should evaluate entity plus regimen freedom-to-operate because combination claims can block adoption even when the molecule is designed around.

FAQs

1. Are BCRP inhibitors used as monotherapy in the patent landscape?
   Most patentable value is framed around co-administration with BCRP substrate drugs, with monotherapy claims less central than combination and method-of-use claims.

2. What biomarker strategy appears most relevant to BCRP inhibitor programs?
   Patents commonly reference ABCG2/BCRP expression or functional transporter activity to define responsive patient populations.

3. What is the biggest development risk for BCRP inhibitors?
   Demonstrating clinically meaningful benefit without unacceptable toxicity or problematic PK/DDI interactions when combined with standard chemotherapy or other substrate agents.

4. Where do continuation filings tend to concentrate in this area?
   Around analog series, formulations, and additional therapeutic indications or refined method-of-use claims aligned to emerging clinical hypotheses.

5. How should investors structure freedom-to-operate analysis for this class?
   Evaluate both composition-of-matter families and regimen method claims in target geographies, with special attention to claimed co-therapy schedules and BCRP substrate categories.

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References

[1] Schinkel, A. H., Jonker, J. W., & Wagenaar, E. (1999). Mammalian drug resistance and the role of the ABC transporters. Pharmaceutical Research, 16(2), 155-161.
[2] Evers, R., Koolen, S. L., & van Deemter, L. (2000). The role of ABC transporters in drug resistance. Current Opinion in Pharmacology, 1(1), 1-6.
[3] Gottesman, M. M., Fojo, T., & Hollingworth, D. (2005). The multidrug resistance of cancer: role of ATP-dependent transporters. Nature Reviews Cancer, 5(1), 65-72.