bavdegalutamide (ARV-110)

We evaluate clinical progression of breakthrough candidates such as ARV-110 for prostate cancer, ARV-471 for breast cancer, and BTK degraders, while discussing critical challenges including the "hook effect" and oral bioavailability limitations. This review provides essential foundations for rational target selection, molecular optimization, and clinical translation strategies. By integrating mechanistic insights with clinical realities, this analysis offers perspectives on PROTAC technology advancement and identifies opportunities for transforming treatment of complex diseases resistant to conventional therapies.

P1, N=45, Completed, Arvinas Androgen Receptor, Inc. | Active, not recruiting --> Completed | Trial completion date: Dec 2025 --> Apr 2025

To support preclinical safety evaluations as well as studies of drug metabolism and pharmacokinetics, two versions of carbon-14-labeled ARV-110 were synthesized: N-((1R,4R)-4-(3-chloro-4-cyanophenoxy)cyclohexyl)-6-(4-((4-(2-(2,6-dioxopiperidin-3-yl)-6-fluoro-1,3-[1,3-14C2]dioxoisoindolin-5-yl)piperazin-1-yl)methyl)piperidin-1-yl)pyridazine-3-carboxamide (14C-ARV-110-a) and N-((1R,4R)-4-(3-chloro-4-[cyano-14C]cyanophenoxy)cyclohexyl)-6-(4-((4-(2-(2,6-dioxopiperidin-3-yl)-6-fluoro-1,3-dioxoisoindolin-5-yl)piperazin-1-yl)methyl)piperidin-1-yl)pyridazine-3-carboxamide (14C-ARV-110-b). The synthesis of 14C-ARV-110-a was initiated from 1,2-dibromo-4,5-difluorobenzene and zinc cyanide-14C (Zn(14CN)₂), while 14C-ARV-110-b was prepared from 2-chloro-4-fluoro[cyano-14C]benzonitrile.

For instance, drugs like ARV-471 and ARV-110 are in advanced phases for treating metastatic breast cancer and prostate cancer, respectively, by targeting estrogen and androgen receptors. The conducted trials not only emphasize the therapeutic potential of protein degradation but also highlight the challenges associated with bioavailability, stability, and delivery mechanisms. As these clinical trials advance, they possess the potential to transform treatment paradigms, providing renewed hope for patients facing complex and refractory conditions.

Several clinically advanced PROTACs, including ARV-110 and ARV-471, demonstrate the therapeutic potential of this technology. Despite challenges in pharmacokinetics and E3 ligase selection, emerging data suggest that PROTACs can successfully target TFs, paving the way for new treatment strategies across oncology and other disease areas.

Consistent with targeting both AR and AR-V7, we find that EN1441 completely inhibits total AR transcriptional activity in androgen-independent prostate cancer cells expressing both AR and AR-V7 compared with AR antagonists or degraders that only target the ligand-binding domain of full-length AR, such as enzalutamide and ARV-110. Our results put forth a pathfinder molecule EN1441 that targets an intrinsically disordered cysteine within AR to destabilize, degrade, and inhibit both AR and AR-V7 in androgen-independent prostate cancer cells and highlights the utility of covalent ligand discovery approaches in directly targeting, destabilizing, inhibiting, and degrading classically undruggable transcription factor targets.

Here, using biotinylated chemical-probe-based target fishing and genetic knockdown/knockin approaches, we discovered that the membrane cluster of differentiation 36 (CD36) binds to and facilitates the uptake and efficacy of diverse PROTACs (e.g., SIM1-Me, MZ1, and clinical ARV-110) and large and/or polar small-molecule drugs (e.g., rapalink-1, rapamycin, navitoclax, birinapant, tubacin, and doxorubicin) via the CD36-mediated early endosome antigen 1 (EEA1)/Ras-related protein 5A (Rab5) endosomal cascade in vitro and/or in vivo. We then devised a novel chemical endocytic medicinal chemistry strategy to improve binding of PROTACs to CD36 using structural modifications via the prodrug approach, markedly enhancing PROTAC anti-tumor efficacy through spontaneously augmenting permeability and solubility.

P1/2, N=248, Completed, Arvinas Inc. | Active, not recruiting --> Completed | Trial primary completion date: Jan 2025 --> Apr 2024

Consistent with targeting both AR and AR-V7, we find that EN1441 completely inhibits total AR transcriptional activity in androgen-independent prostate cancer cells expressing both AR and AR-V7 compared to AR antagonists or degraders that only target the ligand binding domain of full-length AR, such as enzalutamide and ARV-110. Our results put forth a pathfinder molecule EN1441 that targets an intrinsically disordered cysteine within AR to destabilize, degrade, and inhibit both AR and AR-V7 in androgen-independent prostate cancer cells and highlights the utility of covalent ligand discovery approaches in directly targeting, destabilizing, inhibiting, and degrading classically undruggable transcription factor targets.

P1/2, N=250, Active, not recruiting, Arvinas Inc. | Trial primary completion date: Apr 2024 --> Jan 2025

Two prominent PROTACs, ARV-471 and ARV-110, are currently undergoing phase III and II clinical trials, respectively. The concept of covalent degradation has also been utilized in various new forms of degraders, including covalent molecule glue (MG), in-cell click-formed proteolysis targeting chimera (CLIPTAC), HaloPROTAC, lysosome-targeting chimera (LYTAC) and GlueTAC. This review focuses on recent advancements in covalent degraders beyond covalent PROTACs and examines obstacles and future directions pertinent to this field.

Androgen receptor (AR) signaling is the principal driver of prostate cancer, and drugs that target this pathway (e.g., abiraterone and enzalutamide) are standard treatments for metastatic hormone-sensitive prostate cancer and metastatic castration-resistant prostate cancer (mCRPC). These promising preclinical data supported clinical development of bavdegalutamide as a potential treatment for patients with prostate cancer. Bavdegalutamide was the first PROTAC protein degrader to enter human clinical trials, specifically in patients with mCRPC in a phase 1/2 study (NCT03888612).