Revolutionizing Human papillomavirus (HPV)‐related cancer therapies: Unveiling the promise of Proteolysis Targeting Chimeras (PROTACs) and Proteolysis Targeting Antibodies (PROTABs) in cancer nano‐vaccines

Personalized cancer immunotherapies, combined with nanotechnology (nano‐vaccines), are revolutionizing cancer treatment strategies, explicitly targeting Human papilloma virus (HPV)‐related cancers. Despite the availability of preventive vaccines, HPV‐related cancers remain a global concern. Personalized cancer nano‐vaccines, tailored to an individual's tumor genetic mutations, offer a unique and promising solution. Nanotechnology plays a critical role in these vaccines by efficiently delivering tumor‐specific antigens, enhancing immune responses, and paving the way for precise and targeted therapies. Recent advancements in preclinical models have demonstrated the potential of polymeric nanoparticles and high‐density lipoprotein‐mimicking nano‐discs in augmenting the efficacy of personalized cancer vaccines. However, challenges related to optimizing the nano‐carrier system and ensuring safety in human trials persist. Excitingly, the integration of nanotechnology with Proteolysis‐Targeting Chimeras (PROTACs) provides an additional avenue to enhance the effectiveness of personalized cancer treatment. PROTACs selectively degrade disease‐causing proteins, amplifying the impact of nanotechnology‐based therapies. Overcoming these challenges and leveraging the synergistic potential of nanotechnology, PROTACs, and Proteolysis‐Targeting Antibodies hold great promise in pursuing novel and effective therapeutic solutions for individuals affected by HPV‐related cancers.


| BACKGROUND
Human papillomavirus (HPV) poses a significant global health challenge as a leading cause of various cancers, including cervical, oropharyngeal, anal, vulvar, vaginal, and penile cancers. 1 While preventive vaccines have made substantial progress in reducing the incidence of HPV-related cervical cancer, the impact of other HPVrelated malignancies remains a concern. 2 Conventional cancer therapies, such as chemotherapy, radiation, and surgery, often exhibit limitations, including high toxicity and the potential for recurrence, necessitating the exploration of more personalized and efficient treatment approaches. 3 In the realm of personalized medicine, nanotechnology has emerged as a transformative tool for developing innovative strategies against cancer and viral infections.Nano-vaccines, leveraging the precision and immune-stimulating properties of nanotechnology, offer enhanced antigen delivery and improved therapeutic outcomes. 4Moreover, the integration of PROTACs and PROTABs into nano-vaccines introduces a new dimension in the battle against cancer and viral diseases. 5,6PROTACs, a novel class of drugs, demonstrate a unique capability to selectively degrade target proteins within cells. 7,8OTACs are specialized molecules designed to selectively degrade specific proteins within cells.They function by connecting the protein of interest to the cell's natural degradation machinery, ensuring that the targeted protein is broken down and eliminated.
PROTABs are likely antibody-based molecules that, similar to PROTACs, guide proteins toward degradation pathways.The use of antibodies suggests specificity since antibodies can be designed to recognize and bind with high precision to specific proteins or pathogens.
Nano-vaccines employ nanotechnology to enhance the introduction and presentation of antigens to the immune system, optimizing the immune response.A dual-action mechanism, which integrates immune system enhancement with targeted protein degradation, offers a profound therapeutic advantage.
When applied to cancer treatment, the immune system is efficiently directed against cancer cells, while molecules driving the cancer's proliferation or survival are simultaneously degraded.Similarly, against viral infections, the body is trained to recognize the virus and, in tandem, detrimental viral or supportive host proteins may be suppressed.Hence, this combined approach, adeptly combating the disease on two fronts, holds immense promise in pioneering more effective treatments.
By harnessing the power of PROTACs and PROTABs within nano-vaccines, a groundbreaking approach emerges, enabling the simultaneous delivery of antigens and the specific elimination of disease-causing proteins.This dual-action mechanism holds immense promise in personalized cancer treatment and the fight against viral infections.Antigen Delivery: Using nano-vaccines, the body is presented with antigens that train the immune system to recognize and confront specific pathogens or cancerous cells.Specific Protein Elimination: By leveraging PROTACs and Proteolysis-Targeting Antibodies, disease-associated proteins can be identified and degraded.This direct intervention disrupts the disease's molecular components, weakening its effect or progression.When these two mechanisms operate simultaneously, they provide a holistic and robust therapeutic strategy.The immune system is primed to effectively combat the disease while, concurrently, the disease's harmful proteins are being targeted and eliminated.
In the current systematic exploration, we explore the groundbreaking utilization of PROTACs and PROTABs as nano-vaccines in cancer and viral infections, particularly in HPV-related cancers.We delve into the current state of research, shedding light on the potential of this innovative approach to revolutionize treatment outcomes.Additionally, we discuss the challenges and future directions in fully harnessing the potential of nano-vaccines empowered by PROTACs and PROTABs.This exciting convergence represents a new frontier in personalized medicine, offering hope for more effective and targeted therapies against cancer and viral diseases.PROTABS: IMPLICATIONS FOR HPV-RELATED CANCERS PROTACs and PROTABs have emerged as a transformative breakthrough in targeted cancer therapy, capitalizing on the cell's intrinsic protein degradation system to selectively degrade disease-causing proteins. 7,9PROTACs are multifunctional molecules designed with one end binding to the target protein and the other recruiting an E3 ubiquitin ligase, forming a ternary complex. 7This ligase tags the target protein with ubiquitin molecules, marking it for degradation by the 26S proteasome, a crucial complex responsible for degrading ubiquitinated proteins. 10This unique mechanism empowers PRO-TACs to degrade a wide range of target proteins, including traditionally challenging "undruggable" ones.Similarly, PROTABs are engineered antibodies that induce the degradation of their target proteins.Like PROTACs, they exploit the ubiquitin-proteasome pathway for targeted protein degradation. 9The antibody domain of PROTABs binds to the target protein, while the engineered Fc domain recruits an E3 ubiquitin ligase, facilitating ubiquitination of the target protein and marking it for degradation.
In the context of HPV-related cancers, the E6 and E7 oncoproteins emerge as ideal targets for PROTACs and PROTABs.
E6 and E7 are viral proteins consistently expressed in HPVtransformed cells, crucial in initiating and sustaining the malignant phenotype. 11Designing PROTACs and PROTABs to selectively target these oncoproteins for degradation could disrupt the growth and survival of HPV-transformed cells, presenting a promising therapeutic strategy.Furthermore, the degradation of these oncoproteins would generate peptide fragments that could be presented on the cell surface by MHC molecules, potentially triggering an immune response against HPV-transformed cells. 12When combined with the immune-stimulating properties of personalized cancer nanovaccines, a dual mechanism of action could be achieved, paving the way for an innovative and highly effective therapeutic approach for HPV-related cancers.

| UNVEILING THE ONSET OF METASTASIS: EXPLORING IMPLICATIONS FOR HPV-RELATED CANCERS
Metastasis, the intricate process of cancer cell dissemination from the primary tumor to distant organs, presents a formidable challenge in cancer management and remains the primary cause of cancer-related mortality. 13Initiated by the acquisition of invasive properties, cancer cells embark on a journey that involves intravasation, survival in circulation, extravasation, and colonization at distant sites, culminating in the formation of secondary tumors. 3HPV-related cancers, such as cervical cancer and head and neck squamous cell carcinoma, can also undergo metastasis, frequently disseminating to regional lymph nodes and distant locations, such as the lungs. 14,15Crucial to the metastatic cascade in these cancers are the HPV E6 and E7 oncoproteins.E6 and E7 disrupt the functions of tumor suppressor proteins p53 and Rb, respectively, leading to dysregulated cell cycle control, evasion of apoptosis, enhanced cellular motility, and invasivenesskey traits driving the initiation of metastasis. 11gnificantly, HPV E6 and E7 oncoproteins have been implicated in a fundamental process known as epithelial-mesenchymal transition (EMT), which is intimately linked to the onset of metastasis. 16EMT entails the conversion of epithelial cells into a mesenchymal phenotype characterized by augmented migratory capacity and invasiveness.E6 and E7 facilitate EMT by upregulating transcription factors like Snail and Zeb1 17 while downregulating epithelial markers like E-cadherin. 18 light of these findings, therapeutic strategies such as PROTACs and PROTABs designed to degrade E6 and E7 oncoproteins can potentially disrupt metastasis initiation in HPV-related cancers, offering an additional therapeutic benefit.Targeting these oncoproteins could impede the beginning of the metastatic cascade, potentially mitigating the spread of cancer cells to distant sites and improving treatment outcomes in HPV-related cancers.

| NANOTECHNOLOGY-DRIVEN PERSONALIZED HPV-CANCER VACCINES: THE POWER OF PROTACS AND PROTABS FOR PRECISION IMMUNOTHERAPY
Personalized cancer vaccines (Figure 1) have emerged as a promising field of immunotherapy, intending to elicit a patient-specific immune response against the unique antigenic profile of their tumor. 19Within tumors, many distinct genetic mutations known as neoantigens can serve as targets for the immune system.Incorporating these neoantigens into a vaccine can generate a robust and specific immune response against tumor cells expressing these neoantigens.
The integration of nanotechnology has significantly augmented the potential of personalized cancer vaccines within cancer immunotherapy.Nanoparticles have been harnessed as carriers for the efficient delivery of neoantigens, offering enhanced stability, improved cellular uptake, co-delivery of adjuvants, and sustained release of antigens, thereby amplifying the immune-stimulating capacity of the vaccine. 4Notably, nanoparticles have demonstrated their ability to enhance the cross-presentation of antigens to CD8 + T cells, a critical step in generating potent cytotoxic T lymphocyte (CTL) responses against tumors. 20In recent advancements, the advent of Proteolysis-Targeting Chimeras (PROTACs) and Proteolysis-Targeting Antibodies (PROTABs) has revolutionized the landscape of cancer therapy.These innovative therapeutic agents operate through targeted protein degradation, recruiting the cell's ubiquitin-proteasome system to selectively eliminate crucial proteins necessary for the survival and growth of cancer cells. 7,9V-related cancers exhibit unique oncogenic characteristics resulting from the integration of viral DNA into the host genome.This integration leads to the expression of viral oncoproteins E6 and E7, which play a vital role in initiating and sustaining the malignant phenotype. 11This distinct feature presents an exceptional opportunity for the development of personalized nano-vaccines targeting these HPV-specific antigens, providing a highly specific platform for anticancer therapy. 21e potential of these personalized nano-vaccines can be further enhanced by integrating PROTACs and PROTABs.
Designed to target E6 and E7 oncoproteins for degradation, PROTACs and PROTABs offer a dual mechanism of action by simultaneously promoting protein degradation and presenting degraded fragments as antigens for immune recognition. 7,9This innovative approach holds great promise for tackling HPV-related cancers (mentioned in Table 1).
Nanotechnology plays a crucial role in this context by providing an efficient delivery platform for these therapeutic agents to reach the tumor site.Various nanoparticles, such as liposomes, polymerbased nanoparticles, and inorganic nanoparticles, have been utilized to encapsulate and deliver PROTACs and PROTABs, improving their stability, biodistribution, and intracellular uptake. 22For example, liposomal formulations have demonstrated improved pharmacokinetics, leading to enhanced antitumor efficacy of PROTACs. 23iloring personalized nano-vaccines based on the unique characteristics of an individual's HPV-related cancer can generate a potent and specific immune response, potentially eradicating cancer cells.The combination of personalized cancer vaccines, nanotechnologies, and protein degraders like PROTACs and PROTABs represents a promising approach for treating HPV-related cancers.This approach harnesses the oncogenic potential of HPV while leveraging the precision and immune-stimulating capabilities of nanotechnology-driven immunotherapy.Integrating PROTACs or PROTABs into a nanoparticle-based delivery system achieves a synergistic dual mechanism of action.It stimulates an immune response by presenting neoantigens while promoting the degradation of target oncogenic proteins in HPV-related cancers.This convergence of concepts represents an innovative and exciting approach to F I G U R E 1 Application of PROTACs and PROTABs in virus-mediated cancer therapy (created with BioRender.com).PROTAB, Proteolysis-Targeting Antibody; PROTAC, Proteolysis-Targeting Chimera.personalized cancer nano-vaccines, offering tremendous promise for HPV-related cancer treatment.

| POTENTIAL OFF-TARGET EFFECTS AND TOXICITY OF PROTACs AND PROTABs: CHALLENGES OF PROTACs AND PROTABs
While the concept of targeted protein degradation offers a revolutionary approach to disease treatment, translating these findings into clinical applications presents challenges.Ensuring safety is paramount, and any off-target effects or toxicity can have severe implications, especially when considering treatments for lifethreatening diseases like cancer.Comprehensive preclinical studies, including animal models, are vital to assess the safety profile of these molecules before human trials.
• Specificity concerns: Target Protein Misidentification: Although PROTACs and PROTABs are designed for specificity, they might sometimes bind to proteins other than the intended target.This can lead to the degradation of essential proteins, disrupting cellular functions.
• Linker issues: The linker region in these molecules, which bridges the target-binding section with the degradation machinery-binding section, can interact with unintended proteins, leading to their degradation.
• Unforeseen cell signaling disruptions: Degradation of a target protein might inadvertently activate or inhibit secondary signaling pathways within the cell.These cascading effects can have unpredictable consequences on cellular health and function.
• Overloading cellular degradation machinery: Constant targeting and degradation of proteins could strain the cellular proteasome system.Overburdening this machinery might impair its function, impacting overall cellular health.
• Immunological responses: The introduction of foreign molecules like PROTACs and PROTABs could stimulate an immune response.This could range from mild inflammation to severe immunological reactions, depending on the molecule and its interactions within the body.
• Biodistribution and pharmacokinetics: Ensuring that these molecules reach their intended target cells or tissues without accumulating in nontarget areas is crucial.Accumulation in nontarget tissues could lead to unforeseen toxic effects.
• Long-term effects: The long-term effects of constantly degrading target proteins are not fully understood.There might be potential complications arising from chronic use, which could only become apparent after extended periods.
• Resistance development: Just as pathogens can develop resistance to antibiotics, cells might adapt to the constant degradation of specific proteins by upregulating their production or modifying them to avoid PROTAC or PROTAB recognition.
In conclusion, while PROTACs and PROTABs offer a promising avenue for targeted therapeutics, understanding and mitigating their potential off-target effects and toxicity is crucial to ensure their safe and effective translation into clinical applications.

| FUTURE PROSPECTS: PROTACs AND PROTABs AS TARGETED NANO-VACCINES AGAINST HPV-RELATED CANCERS
Integrating PROTACs and PROTABs into nano-vaccines presents a new frontier in the personalized treatment of HPV-related cancers.
These therapeutics capitalize on the cell's natural protein degradation system to selectively target and degrade HPV E6 and E7 oncoproteins, thereby disrupting cancer's growth and survival while simultaneously presenting antigens that stimulate a potent immune response against the cancer cells. 7,9e promising direction is the use of biodegradable nanoparticles to deliver PROTACs and PROTABs, which can enhance their stability and biodistribution, minimize potential off-target effects, and allow for controlled and sustained release at the tumor site. 22In T A B L E 1 Potential targets and mechanisms of action of PROTACs and PROTABs.

Target protein/antigen
Mechanism of action addition, combining PROTACs and PROTABs with other therapeutic agents, such as immune checkpoint inhibitors, could potentiate their anticancer effects. 20Another exciting prospect is the potential for "universal" HPV vaccines that target multiple HPV types.By designing PROTACs and PROTABs that can target conserved regions among different HPV types, these vaccines could provide broad protection against various HPV-related cancers. 24veloping these novel nano-vaccines is in its early stages, and more research is needed to understand and optimize their potential.Key areas of focus include the design of PROTACs and PROTABs to maximize their selectivity and efficacy, the development of nanoparticles for effective delivery, and tailoring vaccines to individual patient's tumor characteristics.As research in this area progresses, it is hoped that these personalized nano-vaccines will provide an effective and durable treatment for patients with HPV-related cancers, improving outcomes and quality of life.7 | CONCLUSIONIn conclusion, integrating nanotechnology and the innovative design of PROTACs and PROTABs can potentially revolutionize the treatment landscape for HPV-related cancers.These unique therapeutic modalities leverage the cell's natural protein degradation system, offering a dual mechanism of action that includes the targeted degradation of HPV E6 and E7 oncoproteins to inhibit cancer growth and stimulate the immune system to eliminate cancer cells.Incorporating PROTACs and PROTABs into personalized cancer nano-vaccines capitalizes on the advantages of nanotechnology and targeted protein degradation, providing highly selective, effective, and patient-specific therapies.This approach can potentially overcome the limitations of current treatments by enabling the degradation of traditionally "undruggable" targets, reducing systemic toxicity, and enhancing the immune response against cancer cells.The novelty of utilizing PROTACs and PROTABs as cancer nanovaccines for HPV-related cancers lies in their unique mechanism of action and high specificity.By selectively targeting and degrading HPV oncoproteins, these therapies can effectively disrupt the growth and survival of HPV-transformed cells.Additionally, the degradation of these oncoproteins generates peptide fragments that can stimulate a potent immune response against cancer cells, further augmenting their therapeutic effect.Furthermore, encapsulating these therapeutics in nanoparticles improves their stability, biodistribution, and delivery to the tumor site, enhancing their efficacy while minimizing off-target effects.The ability to tailor these nanovaccines to the specific characteristics of individual patient's tumors underscores their potential for personalized cancer treatment.The convergence of nanotechnology, targeted protein degradation, and personalized medicine through PROTAC-and PROTABbased nano-vaccines represents a new era in treating HPV-related cancers.While further research is necessary to fully realize their potential, the progress made thus far is promising and provides a strong foundation for future advancements.As we unravel the complexities of HPV-related cancers, these innovative therapeutic strategies promise improved outcomes and enhanced quality of life for patients.