Cancer Treatment and Research

Hormonal Therapies in Cancers

The hormonal therapy for cancer has become a household name and the series of experiments performed leading to the discovery of hormones use in the treatments of breast cancer. The hormones like antiestrogen, aromatase restrictors, antiandrogens, and use of extremely strong luteinizing hormone-releasing hormone agonists to perform a "medical hypophysectomy" because of their ability of causing desensitization in the pituitary gland have proven their value in the treatment of cancers over the last two decades. Millions of women still use hormonal therapy for menopause symptoms. Estrogen plus progestin or estrogen separately utilized as a menopause hormonal therapy throughout the world. Women receiving different premenopausal and postmenopausal hormonal therapies are on higher risk of having ovarian cancer. The risk of ovarian cancer did not increase with the increase of duration of hormonal therapy. Postmenopausal hormone use was found to be inversely related to major colorectal adenomas.

The Immune Landscape in Women Cancers

In this chapter, we summarize the latest findings in the field of immuno-oncology of women cancers, particularly ovarian and breast tumors. We describe the relationship between immune parameters and clinical outcomes by evaluating the contribution of different players of the tumor microenvironment, with a particular focus on different immune cell subsets and their essential role during the development of the disease, the response to standard chemotherapy, and to emerging immunotherapeutic approaches. By reviewing the molecular and genetic features of ovarian and breast cancer subtypes, we report on the multitude of factors influencing treatment outcome, with a particular interest on the possible influence of the immune system (i.e., tumor infiltrating lymphocytes, T cells, regulatory T cells, myeloid-derived suppressor cells, dendritic cells, macrophages, B cells, tumor-associated neutrophils). Finally, we discuss emerging immune targets and novel therapeutic modalities that are likely to profoundly influence clinical outcome and prognosis of breast and ovarian cancers in the next future.

Clinical Use of PARP Inhibitors in BRCA Mutant and Non-BRCA Mutant Breast Cancer

The use of poly(ADP-ribose) polymerase (PARP) inhibitors for the treatment of patients with germline BRCA mutations (gBRCAm) and breast cancer, both in the early and advanced settings, is a success of genomically-directed treatment. These agents have been shown to be associated with longer progression-free survival when compared to standard chemotherapy, with an acceptable toxicity profile. A recent randomized trial demonstrated improved survival with the use of olaparib for 2 years compared to placebo in patients with early-stage high risk gBRCAm associated breast cancer. Ongoing research efforts are focused on identifying patients beyond those with BRCA1/2 or PALB2 mutations who may benefit from PARP inhibitors, exploring the overlapping mechanisms of resistance between platinum and PARP inhibitors and developing agents with less toxicity that will allow combinational strategies.

Clinical Application of Poly(ADP-Ribose) Polymerase (PARP) Inhibitors in Ovarian Cancer

The treatment of ovarian cancer has remained a clinical challenge despite high rates of initial response to platinum-based chemotherapy. Patients are generally diagnosed at an advanced stage with significant disease burden, which portends to worse survival outcomes. Deficiencies in the homologous recombination (HRD) DNA damage repair (DDR) pathway and mutations in the BRCA1/2 genes have been found in ovarian carcinomas. Moreover, patients with these specific molecular aberrations have demonstrated sensitivity and thus improved response to poly(ADP-ribose) polymerase inhibitor (PARPi) treatment. The results of various clinical trials exploring the use of PARPi in different populations of ovarian cancer patients have shown impressive survival and response outcomes. With expanding indications, the use of PARPi has thus changed the landscape of ovarian cancer treatment. In this chapter, we will describe the different settings of PARPi treatment-frontline maintenance therapy, maintenance therapy for patients with recurrent platinum-sensitive disease, and treatment in the recurrent setting-and discuss treatment considerations and management of toxicities, as well as offer thoughts on future directions.

Role of Immunotherapy in Ovarian Cancer: Advances, Challenges, and Future Perspectives

Ovarian cancer (OC) remains one of the most challenging gynecologic malignancies due to its late-stage diagnosis, high recurrence rates, and limited survival outcomes. Immunotherapy has emerged as a transformative approach in cancer treatment, leveraging the immune system to target tumor cells. This chapter provides a comprehensive overview of immunotherapy in OC, discussing its mechanisms, key strategies, and clinical advancements. Key areas include the role of immune checkpoint inhibitors (ICIs), adoptive cell therapies (ACT), cancer vaccines, and oncolytic viruses. Despite promising preclinical and clinical outcomes, significant challenges persist, including low immunogenicity, resistance mechanisms, and immune-related adverse events. Strategies to address these barriers, such as combination therapies, biomarker-guided approaches, and the integration of artificial intelligence (AI) for personalization, are discussed. Emerging directions, including next-generation immune checkpoint targets and innovations in epigenetic and metabolic reprogramming, are explored to envision the future of immunotherapy in OC. By addressing these challenges and leveraging innovative strategies, immunotherapy has the potential to redefine the therapeutic landscape, improving survival and quality of life for patients with OC.

Rational Combinations of PARP Inhibitors with HRD-Inducing Molecularly Targeted Agents

Cancers with wild-type BRCA, homologous recombination proficiency, or de novo or acquired resistance to PARP inhibition represent a growing population of patients who may benefit from combinatorial PARP inhibitor strategies. We review targeted inhibitors of angiogenesis, epigenetic regulators, and PI3K, MAPK, and other cellular signaling pathways as inducers of homologous recombination deficiency, providing support for the use of PARP inhibitors in contexts not previously considered susceptible to PARP inhibition.

Development of PARP Inhibitors in Targeting Castration-Resistant Prostate Cancer

Combination DNA Damage Response (DDR) Inhibitors to Overcome Drug Resistance in Ovarian Cancer

The DNA damage response (DDR) results in activation of a series of key target kinases that respond to different DNA damage insults. DDR inhibitors such as PARP inhibitors lead to the accumulation of DNA damage in tumor cells and ultimately apoptosis. However, responses to DDRi monotherapy in the clinic are not durable and resistance ultimately develops. DDRi-DDRi combinations such as PARPi-ATRi, PAPRi-WEE1i and PARPi-AsiDNA can overcome multiple resistance mechanisms to PARP inhibition. In addition, DDRi-DDRi combinations can provide viable treatment options for patients with platinum-resistant disease. In the present chapter we discuss rationale of DDRi-DDRi strategies that capitalize on genomic alterations found in ovarian cancer and other solid tumors and may provide in the near future new treatment options for these patients.

Development of Homologous Recombination Functional Assays for Targeting the DDR

Identification of tumours that have homologous recombination deficiency (HRD) has become of increasing interest following the licensing of PARP inhibitors. Potential methods to assess HRD status include; clinical selection for platinum sensitive disease, mutational/methylation status, genomic scars/signature and functional RAD51 assays. Homologous recombination (HR) is a dynamic process with the potential to evolve over a disease course, particularly in relation to previous treatment. This is one of the major drawbacks of genomic scars/signatures, as they only demonstrate historic HR status. Functional HR assays have the benefit of giving a real time HR status readout and therefore have the potential for clearer identification of patients who may benefit from PARP inhibitors at that specific time point. However, the development of RAD51 foci assays ready for clinical practice has been challenging. Pre-clinical considerations have included; controlling for variation in tumour proliferation, tissue type and whether DNA damage induction is required. Furthermore, the assays require correlation with clinical outcomes, an understanding of how they complement current testing modalities and validation of test performance in large cohorts. Despite these challenges, given the profound benefit from PARP inhibitors seen in those with an HRD phenotype to date, the ongoing development and validation of these functional HR assays remains of high clinical importance.

Mechanisms of PARP Inhibitor Resistance

Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) represent the first medicines based on the targeting of the DNA damage response (DDR). PARPi have become standard of care for first-line maintenance treatment in ovarian cancer and have also been approved in other cancer indications including breast, pancreatic and prostate. Despite their efficacy, resistance to PARPi has been reported clinically and represents a growing patient population with unmet clinical need. Here, we describe the various mechanisms of PARPi resistance that have been identified in pre-clinical models and in the clinic.

Combining Poly (ADP-Ribose) Polymerase (PARP) Inhibitors with Chemotherapeutic Agents: Promise and Challenges

Better understanding of molecular drivers and dysregulated pathways has furthered the concept of precision oncology and rational drug development. The role of DNA damage response (DDR) pathways has been extensively studied in carcinogenesis and as potential therapeutic targets to improve response to chemotherapy or overcome resistance. Treatment with small molecule inhibitors of PARP has resulted in clinical response and conferred survival benefit to patients with ovarian cancer, BRCA-mutant breast cancer, HRD-deficient prostate cancer and BRCA-mutant pancreatic cancer, leading to US Food and Drug Administration (FDA) approvals. However, the observed clinical benefit with single agent PARP inhibitors is limited to few tumor types within the relevant genetic context. Since DDR pathways are essential for repair of damage caused by cytotoxic agents, PARP inhibitors have been evaluated in combination with various chemotherapeutic agents to broaden the therapeutic application of this class of drugs. In this chapter, we discuss the combination of PARP inhibitors with different chemotherapeutics agents, clinical experience to date, lessons learnt, and future directions for this approach.