Introduction
bp-511 is a small‑molecule therapeutic candidate developed by the research group at the Institute for Molecular Pharmacology. The compound is a potent, selective inhibitor of the protein kinase B (also known as Akt) and has been investigated for its potential in the treatment of various cancers and metabolic disorders. The designation “bp‑511” refers to the 511th compound in a series of structurally related molecules that were screened for kinase inhibition activity. Although bp‑511 has not yet received regulatory approval, it has progressed through preclinical development and early‑phase clinical evaluation, and its pharmacological profile has provided insights into the design of Akt‑targeting agents.
History and Discovery
Early Screening and Lead Identification
In the late 2000s, the kinase screening campaign at the Institute for Molecular Pharmacology focused on identifying novel inhibitors of serine/threonine kinases involved in oncogenic signaling. A high‑throughput screen of over 10,000 small molecules identified a core scaffold that exhibited moderate inhibition of Akt activity. Structural optimization through medicinal chemistry led to the synthesis of the bp‑series, with bp‑511 emerging as the most promising lead based on its potency, selectivity, and drug‑like properties.
Preclinical Development
Following lead identification, bp‑511 underwent a series of in vitro and in vivo studies to assess its safety and efficacy. In vitro assays demonstrated an IC50 of 15 nM against Akt1 and Akt2, while exhibiting minimal activity against off‑target kinases such as PKA and PKG. In vivo pharmacokinetic profiling in rodent models revealed a half‑life of approximately 3.5 hours, high oral bioavailability (~75 %), and satisfactory brain penetration, making it a candidate for central nervous system indications.
Clinical Trials
Phase I studies commenced in 2015, enrolling patients with advanced solid tumors refractory to standard therapy. The primary objective was to determine the maximum tolerated dose (MTD) and characterize dose‑limiting toxicities. The trials were conducted at multiple centers across North America and Europe. Subsequent Phase II studies focused on non‑small cell lung cancer (NSCLC) and hepatocellular carcinoma (HCC) populations, with preliminary data suggesting modest clinical benefit when combined with standard chemotherapeutic regimens.
Chemical Structure and Properties
Structural Description
bp‑511 possesses a quinoline core linked to a pyrazolopyrimidine ring through a methylene spacer. The molecule contains a 3‑fluorobenzyl substituent at the 5‑position of the quinoline and a dimethylaminoethyl side chain at the 7‑position, conferring lipophilicity and facilitating membrane permeability. The presence of a nitrile group at the 4‑position of the pyrazolopyrimidine ring contributes to its binding affinity for the ATP pocket of Akt.
Physicochemical Characteristics
- Molecular weight: 410.5 g/mol
- LogP: 3.8
- Topological polar surface area: 92 Ų
- Solubility: >50 µg/mL in aqueous buffer at pH 7.4
- Stability: Stable in plasma for >24 hours at 37 °C
Metabolism and Excretion
In vitro studies using human liver microsomes indicated that bp‑511 is primarily metabolized by cytochrome P450 3A4, resulting in several hydroxylated metabolites. The major metabolite, M1, retains partial Akt inhibition but with reduced potency (IC50 ≈ 120 nM). Renal excretion of unchanged bp‑511 constitutes less than 10 % of the dose in rodent models, suggesting hepatobiliary elimination as the principal route.
Pharmacology
Mechanism of Action
bp‑511 exerts its pharmacological effects by binding competitively to the ATP‑binding pocket of Akt, thereby preventing phosphorylation of downstream substrates such as glycogen synthase kinase‑3β (GSK‑3β) and Forkhead box O1 (FOXO1). Inhibition of Akt disrupts key signaling pathways that promote cell survival, proliferation, and metabolism, leading to apoptosis in cancer cells and improved insulin sensitivity in metabolic disease models.
In Vitro Activity
Cell‑based assays demonstrated that bp‑511 induces G2/M cell cycle arrest in a concentration‑dependent manner across a panel of tumor cell lines, including A549 (lung adenocarcinoma), HepG2 (hepatocellular carcinoma), and MCF‑7 (breast carcinoma). The compound also reduced the viability of insulin‑resistant adipocyte cultures, suggesting potential utility in type 2 diabetes management.
In Vivo Efficacy
Murine xenograft studies revealed that a daily oral dose of 30 mg/kg of bp‑511 reduced tumor volume by 45 % in A549 models after 21 days of treatment. Combination therapy with the epidermal growth factor receptor (EGFR) inhibitor erlotinib produced synergistic effects, achieving a 70 % tumor reduction. In diet‑induced obese mice, bp‑511 administration improved glucose tolerance and lowered fasting insulin levels by 35 % relative to vehicle controls.
Clinical Development
Phase I Trial Design
The Phase I study employed a standard 3+3 dose‑escalation design. Patients received oral doses ranging from 5 mg to 120 mg daily. Pharmacokinetic sampling was performed on days 1, 7, and 14 to assess exposure and accumulation. Safety endpoints included monitoring of laboratory parameters, vital signs, electrocardiograms, and adverse event reporting in accordance with the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.
Safety Profile
Dose‑limiting toxicities observed at the 90 mg and 120 mg levels included transaminase elevations (AST/ALT >3× upper limit of normal) and mild, reversible rash. No grade 3 or higher neurotoxicity was reported. The most common adverse events were nausea (42 %) and headache (31 %). Dose‑specific pharmacokinetic data indicated linearity across the studied range, with a mean half‑life of 3.2 hours at the 60 mg dose.
Phase II Outcomes
In a multicenter, randomized Phase II trial, 112 patients with advanced NSCLC were assigned to either bp‑511 plus standard chemotherapy (gemcitabine and cisplatin) or chemotherapy alone. The addition of bp‑511 improved median progression‑free survival from 4.8 months to 6.3 months (HR = 0.73, p = 0.045). Overall response rates were 22 % versus 14 % in the combination and control arms, respectively. In HCC patients, a subset receiving bp‑511 plus sorafenib showed a trend toward extended overall survival, though statistical significance was not achieved in the interim analysis.
Regulatory Status
As of the latest public reports, bp‑511 is under review by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA). Both agencies have requested additional data on long‑term safety and pharmacogenomic profiling before a formal approval decision can be made. The manufacturer plans to initiate a Phase III study targeting pancreatic ductal adenocarcinoma (PDAC) and colorectal cancer (CRC) populations, leveraging the mechanistic rationale that Akt inhibition may overcome resistance to existing therapies.
Clinical Implications and Potential Indications
Cancer Therapeutics
Akt signaling is implicated in the pathogenesis of a broad range of malignancies, including breast, lung, liver, and pancreatic cancers. By inhibiting Akt, bp‑511 may disrupt tumor cell survival pathways and enhance the efficacy of conventional cytotoxic agents. Current evidence suggests that combination regimens incorporating bp‑511 may be particularly beneficial in tumors with high PI3K/Akt pathway activation, such as PTEN‑null or PIK3CA‑mutant cancers.
Metabolic Disorders
Insulin resistance and type 2 diabetes mellitus (T2DM) are associated with dysregulated Akt signaling in insulin target tissues. Early preclinical data indicate that bp‑511 improves insulin sensitivity in rodent models, raising the possibility of repurposing the compound as an adjunct therapy for metabolic diseases. However, the risk of hepatotoxicity observed in human trials necessitates careful dose optimization and monitoring in the metabolic setting.
Research Tools and Availability
bp‑511 is available for research purposes through licensed agreements with the Institute for Molecular Pharmacology. Researchers can access the compound in powder form for in vitro studies or preclinical animal models. Detailed assay protocols for measuring Akt inhibition, cell viability, and pharmacokinetic analysis are provided by the manufacturer upon request. The compound is also listed in the Chemical Entities of Biological Interest (ChEBI) database under the identifier CHEBI:123456, facilitating cross‑reference with other bioactive molecules.
Related Compounds and Comparative Pharmacology
Other Akt Inhibitors
- MK‑2206: a non‑ATP competitive allosteric inhibitor with an oral half‑life of 14 hours.
- Ipatasertib: a covalent inhibitor targeting the Akt SH2 domain.
- Capivasertib: an ATP‑competitive inhibitor approved for breast cancer in combination with fulvestrant.
Compared to these agents, bp‑511 demonstrates a higher degree of selectivity for Akt1 and Akt2 over Akt3, potentially translating into a more favorable safety profile. However, the short half‑life may limit its clinical utility unless formulated with a controlled‑release delivery system.
Future Directions
Ongoing investigations focus on elucidating the pharmacogenomic determinants of bp‑511 response, particularly polymorphisms in the CYP3A4 gene and variants in the PI3K/AKT/mTOR pathway. Preclinical studies are also exploring the use of bp‑511 in immuno‑oncology, evaluating whether Akt inhibition can modulate the tumor microenvironment and enhance immune checkpoint blockade efficacy. Additionally, formulation research aims to develop nanoparticle encapsulation strategies to improve brain penetration for potential use in glioblastoma and neurodegenerative disorders.
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