Targeting cancer with small-molecule pan-KRAS degraders.

Mutations in the Kirsten rat sarcoma viral oncogene homolog (KRAS) protein are highly prevalent in cancer. However, small-molecule concepts that address oncogenic KRAS alleles remain elusive beyond replacing glycine at position 12 with cysteine (G12C), which is clinically drugged through covalent inhibitors. Guided by biophysical and structural studies of ternary complexes, we designed a heterobifunctional small molecule that potently degrades 13 out of 17 of the most prevalent oncogenic KRAS alleles. Compared with inhibition, KRAS degradation results in more profound and sustained pathway modulation across a broad range of KRAS mutant cell lines, killing cancer cells while sparing models without genetic KRAS aberrations. Pharmacological degradation of oncogenic KRAS was tolerated and led to tumor regression in vivo. Together, these findings unveil a new path toward addressing KRAS-driven cancers with small-molecule degraders.

Targeted degradation of KRAS protein in non-small cell lung cancer: Therapeutic strategies using liposomal PROTACs with enhanced cellular uptake and pharmacokinetic profiles.

The role of KRAS mutation in non-small cell lung cancer (NSCLC) initiation and progression is well-established. However, "undruggable" KRAS protein poses the research of small molecule inhibitors a significant challenge. Addressing this, proteolysis-targeting chimeras (PROTACs) have become a cutting-edge treatment method, emphasizing protein degradation. A modified ethanol injection method was employed in this study to formulate liposomes encapsulating PROTAC drug LC-2 (LC-2 LPs). Precise surface modifications using cell-penetrating peptide R8 yielded R8-LC-2 liposomes (R8-LC-2 LPs). Comprehensive cellular uptake and cytotoxicity studies unveiled that R8-LC-2 LPs depended on concentration and time, showcasing the superior performance of R8-LC-2 LPs compared to normal liposomes. In vivo pharmacokinetic profiles demonstrated the capacity of DSPE-PEG2000 to prolong the circulation time of LC-2, leading to higher plasma concentrations compared to free LC-2. In vivo antitumor efficacy research underscored the remarkable ability of R8-LC-2 LPs to effectively suppress tumor growth. This study contributed to the exploration of enhanced therapeutic strategies for NSCLC, specifically focusing on the development of liposomal PROTACs targeting the "undruggable" KRAS protein. The findings provide valuable insights into the potential of this innovative approach, offering prospects for improved drug delivery and heightened antitumor efficacy.

Discovery of a potent CDKs/FLT3 PROTAC with enhanced differentiation and proliferation inhibition for AML.

AML is an aggressive malignancy of immature myeloid progenitor cells. Discovering effective treatments for AML through cell differentiation and anti-proliferation remains a significant challenge. Building on previous studies on CDK2 PROTACs with differentiation-inducing properties, this research aims to enhance CDKs degradation through structural optimization to facilitate the differentiation and inhibit the proliferation of AML cells. Compound C3, featuring a 4-methylpiperidine ring linker, effectively degraded CDK2 with a DC50 value of 18.73 ± 10.78 nM, and stimulated 72.77 ± 3.51 % cell differentiation at 6.25 nM in HL-60 cells. Moreover, C3 exhibited potent anti-proliferative activity against various AML cell types. Degradation selectivity analysis indicated that C3 could be endowed with efficient degradation of CDK2/4/6/9 and FLT3, especially FLT3-ITD in MV4-11 cells. These findings propose that C3 combined targeting CDK2/4/6/9 and FLT3 with enhanced differentiation and proliferation inhibition, which holds promise as a potential treatment for AML.

Bioinspired PROTAC-induced macrophage fate determination alleviates atherosclerosis.

Atherosclerosis is a major cause of death and disability in cardiovascular disease. Atherosclerosis associated with lipid accumulation and chronic inflammation leads to plaques formation in arterial walls and luminal stenosis in carotid arteries. Current approaches such as surgery or treatment with statins encounter big challenges in curing atherosclerosis plaque. The infiltration of proinflammatory M1 macrophages plays an essential role in the occurrence and development of atherosclerosis plaque. A recent study shows that TRIM24, an E3 ubiquitin ligase of a Trim family protein, acts as a valve to inhibit the polarization of anti-inflammatory M2 macrophages, and elimination of TRIM24 opens an avenue to achieve the M2 polarization. Proteolysis-targeting chimera (PROTAC) technology has emerged as a novel tool for the selective degradation of targeting proteins. But the low bioavailability and cell specificity of PROTAC reagents hinder their applications in treating atherosclerosis plaque. In this study we constructed a type of bioinspired PROTAC by coating the PROTAC degrader (dTRIM24)-loaded PLGA nanoparticles with M2 macrophage membrane (MELT) for atherosclerosis treatment. MELT was characterized by morphology, size, and stability. MELT displayed enhanced specificity to M1 macrophages as well as acidic-responsive release of dTRIM24. After intravenous administration, MELT showed significantly improved accumulation in atherosclerotic plaque of high fat and high cholesterol diet-fed atherosclerotic (ApoE-/-) mice through binding to M1 macrophages and inducing effective and precise TRIM24 degradation, thus resulting in the polarization of M2 macrophages, which led to great reduction of plaque formation. These results suggest that MELT can be considered a potential therapeutic agent for targeting atherosclerotic plaque and alleviating atherosclerosis progression, providing an effective strategy for targeted atherosclerosis therapy.

Targeted MDM2 Degradation Reveals a New Vulnerability for p53-Inactivated Triple-Negative Breast Cancer.

Triple-negative breast cancers (TNBC) frequently inactivate p53, increasing their aggressiveness and therapy resistance. We identified an unexpected protein vulnerability in p53-inactivated TNBC and designed a new PROteolysis TArgeting Chimera (PROTAC) to target it. Our PROTAC selectively targets MDM2 for proteasome-mediated degradation with high-affinity binding and VHL recruitment. MDM2 loss in p53 mutant/deleted TNBC cells in two-dimensional/three-dimensional culture and TNBC patient explants, including relapsed tumors, causes apoptosis while sparing normal cells. Our MDM2-PROTAC is stable in vivo, and treatment of TNBC xenograft-bearing mice demonstrates tumor on-target efficacy with no toxicity to normal cells, significantly extending survival. Transcriptomic analyses revealed upregulation of p53 family target genes. Investigations showed activation and a required role for TAp73 to mediate MDM2-PROTAC-induced apoptosis. Our data, challenging the current MDM2/p53 paradigm, show MDM2 is required for p53-inactivated TNBC cell survival, and PROTAC-targeted MDM2 degradation is an innovative potential therapeutic strategy for TNBC and superior to existing MDM2 inhibitors. SIGNIFICANCE: p53-inactivated TNBC is an aggressive, therapy-resistant, and lethal breast cancer subtype. We designed a new compound targeting an unexpected vulnerability we identified in TNBC. Our MDM2-targeted degrader kills p53-inactivated TNBC cells, highlighting the requirement for MDM2 in TNBC cell survival and as a new therapeutic target for this disease. See related commentary by Peuget and Selivanova, p. 1043. This article is highlighted in the In This Issue feature, p. 1027.

PROTAC Degraders of Androgen Receptor-Integrated Dissolving Microneedles for Androgenetic Alopecia and Recrudescence Treatment via Single Topical Administration.

Androgenetic alopecia (AGA) is a transracial and cross-gender disease worldwide with a youth-oriented tendency, but it lacks effective treatment. The binding of androgen receptor (AR) and androgen plays an essential role in the occurrence and progression of AGA. Herein, novel proteolysis targeting chimera degrader of AR (AR-PROTAC) is synthesized and integrated with dissolving microneedles (PROTAC-MNs) to achieve AR destruction in hair follicles for AGA treatment. The PROTAC-MNs possess adequate mechanical capabilities for precise AR-PROTAC delivery into the hair follicle-residing regions for AR degradation. After applying only once topically, the PROTAC-MNs achieve an accelerated onset of hair regeneration as compared to the daily application of the first-line topical drug minoxidil. Intriguingly, PROTAC-MNs via single administration still realize superior hair regeneration in AGA recrudescence, which is the major drawback of minoxidil in clinical practice. With the degradation of AR, the PROTAC-MNs successfully regulate the signaling cascade related to hair growth and activate hair follicle stem cells. Furthermore, the PROTAC-MNs do not cause systemic toxicity or androgen deficiency-related chaos in vivo. Collectively, these AR-degrading dissolving microneedles with long-lasting efficacy, one-step administration, and high biocompatibility provide a great therapeutic potential for AGA treatment.