373MO Delivery and activity of SN-38 by sacituzumab govitecan in CNS tumours

Poly(ADP-ribose) polymerase inhibitors in the treatment landscape of triple-negative breast cancer (TNBC)

OBJECTIVE

Chemotherapy is the mainstay for triple-negative breast cancer (TNBC) patients. Over the years, the use of chemotherapy for these patients has demonstrated many adversities, including toxicity and resistance, which suggested the need to develop novel alternative therapeutic options, such as poly(ADP-ribose) polymerase inhibitors (PARPi). Herein, we provide an overview on PARPi, mechanisms of action and the role of biomarkers in PARPi sensitivity trials, clinical advances in PARPi therapy for TNBC patients based on the most recent studies and findings of clinical trials, and challenges that prevent PARP inhibitors from achieving high efficacy such as resistance and overlapping toxicities with other chemotherapies.

DATA SOURCES

Searching for relevant articles was done using PubMed and Cochrane Library databases by using the keywords including TNBC; chemotherapy; PARPi; BRCA; homologous recombination repair (HRR). Studies had to be published in full-text in English in order to be considered.

DATA SUMMARY

Although PARPi have been used in the treatment of local/metastatic breast malignancies that are HER2 negative and has a germline BRCA mutation, several questions are still to be answered in order to maximize the clinical benefit of PARP inhibitors in TNBC treatment, such as questions related to the optimal use in the neoadjuvant and metastatic settings as well as the best combinations with various chemotherapies.

CONCLUSIONS

PARPi are emerging treatment options for patients with gBRCA1/2 mutations. Determining patients that are most likely to benefit from PARPi and identifying the optimal treatment combinations with high efficacy and fewer side effects are currently ongoing.

Antibody-Drug Conjugates: A New Therapeutic Approach for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subset associated with a worse prognosis and poor response to conventional chemotherapy. Despite recent advances in drug discovery, its management is still a challenge for clinicians, illuminating the unmet need to develop novel treatment approaches. Antibody-drug conjugates (ADC) are innovative oncology drugs that combine the specificity of monoclonal antibodies and the high efficacy of anticancer payloads, to deliver cytotoxic drugs selectively to cancer cells. Various ADCs were investigated for TNBC and have provided a promise for this aggressive women's cancer including the FDA-approved sacituzumab govitecan. In this chapter, we reviewed different ADCs studied for TNBC including their mechanisms of action, efficacy, and tolerability. Moreover, we have also discussed their therapeutic potential based on combinatorial approaches with other targeted therapies in early and metastatic TNBC.

Breast Cancer Brain Metastases: Achilles' Heel in Breast Cancer Patients' Care

Brain metastases (BM) significantly affect the prognosis as well as the quality of life of breast cancer (BC) patients. Although advancements in neurosurgical and radiotherapy techniques improve local control and symptom management, BM remains associated with a poor prognosis. In addition, the efficacy of currently approved systemic therapies in central nervous system (CNS) compartment is still limited, especially after progression on local therapy. The blood-brain barrier (BBB) has been recognized as a mechanism of primary resistance to many chemotherapeutic agents and targeted therapies due to low drug penetration. Other mechanisms of primary and secondary resistance are still unclear and may vary across the BC subtypes. New small molecules have demonstrated efficacy in BM, in particular for the HER2-positive subtype, with a benefit in survival. A new era has begun in the field of BM, and many trials specifically designed for this population are currently ongoing. The BC research community needs to address this call with the final aim of improving the efficacy of systemic therapy in CNS compartment and ultimately preventing the occurrence of BM.

Salvage Treatment for Progressive Brain Metastases in Breast Cancer

Simple Summary

Thirty percent of patients with human epidermal growth factor receptor 2-positive breast cancer and triple-negative breast cancer, and 15% of patients with the remaining subtypes of breast cancer will develop brain metastases. Available treatment methods include surgery and radiotherapy. However, some individuals will experience intracranial progression despite prior local treatment. This situation remains a challenge. In the case of progressing lesions amenable to local therapy, the choice of a treatment method must consider performance status, cancer burden, possible toxicity, and previously applied therapy. Stereotactic radiosurgery or fractionated radiotherapy rather than whole-brain radiotherapy should be used only if feasible. If local therapy is unfeasible, selected patients, especially those with human epidermal growth factor receptor 2-positive breast cancer, may benefit from systemic therapy.

Abstract

Survival of patients with breast cancer has increased in recent years due to the improvement of systemic treatment options. Nevertheless, the occurrence of brain metastases is associated with a poor prognosis. Moreover, most drugs do not penetrate the central nervous system because of the blood–brain barrier. Thus, confirmed intracranial progression after local therapy is especially challenging. The available methods of salvage treatment include surgery, stereotactic radiosurgery (SRS), fractionated stereotactic radiotherapy (FSRT), whole-brain radiotherapy, and systemic therapies. This narrative review discusses possible strategies of salvage treatment for progressive brain metastases in breast cancer. It covers possibilities of repeated local treatment using the same method as applied previously, other methods of local therapy, and options of salvage systemic treatment. Repeated local therapy may provide a significant benefit in intracranial progression-free survival and overall survival. However, it could lead to significant toxicity. Thus, the choice of optimal methods should be carefully discussed within the multidisciplinary tumor board.

Central Nervous System Metastases from Triple-Negative Breast Cancer: Current Treatments and Future Prospective

It is estimated that approximately one-third of patients with triple-negative breast cancer (TNBC) will develop brain metastases. The prognosis for patients with breast cancer brain metastasis has improved in the recent past, especially for hormone receptor and human epidermal growth factor receptor 2 (HER) positive subtypes. However, the overall survival rate for patients with triple-negative subtype remains poor. The development of newer treatment options, including antibody-drug conjugates such as Sacituzumab govitecan, is particularly encouraging. This article reviews the clinical outcomes, challenges, and current approach to the treatment of brain metastasis in TNBC. We have also briefly discussed newer treatment options and ongoing clinical trials. The development of brain metastasis significantly decreases the quality of life of patients with TNBC, and newer treatment strategies and therapeutics are the need of the hour for this disease subgroup.

Targeting brain metastases in breast cancer

Brain metastases (BMs) are an important source of morbidity and mortality in patients with metastatic breast cancer (BC). As survival of patients with advanced BC considerably improved thanks to research advancements and new therapeutic approaches, the apparent incidence of BMs is increasing. Local interventions, in the form of either surgical resection or radiation therapy, remain the mainstay in the management of BMs. Systemic treatments are typically used to complement local strategies to further improve and maintain control of central nervous system (CNS) disease. Although high-level evidence data about the impact of the blood-brain barrier (BBB), as well as the efficacy of anti-cancer agents on BMs and differentials between the systemic compartment and CNS are still scant, our understanding of the activity of systemic treatments with impact on BMs is rapidly evolving. Novel anti-HER2 agents, such as tucatinib, ado-trastuzumab emtansine, trastuzumab deruxtecan and neratinib, have shown intracranial efficacy. Current research efforts are ongoing not only to clarify the activity of existing treatments on the CNS, as well as to develop new drugs and innovative multi-modality approaches. This review will encompass the current treatment landscape of BMs arising from BC, with a focus on recent advancements in the field and investigational approaches.

Antibody Drug Conjugates in Glioblastoma - Is There a Future for Them?

Glioblastoma (GBM) is an aggressive and fatal malignancy that despite decades of trials has limited therapeutic options. Antibody drug conjugates (ADCs) are composed of a monoclonal antibody which specifically recognizes a cellular surface antigen linked to a cytotoxic payload. ADCs have demonstrated superior efficacy and/or reduced toxicity in a range of haematological and solid tumors resulting in nine ADCs receiving regulatory approval. ADCs have also been explored in patients with brain tumours but with limited success to date. While earlier generations ADCs in glioma patients have had limited success and high toxicity, newer and improved ADCs characterised by low immunogenicity and more effective payloads have shown promise in a range of tumour types. These newer ADCs have also been tested in glioma patients, however, with mixed results. Factors affecting the effectiveness of ADCs to target the CNS include the blood brain barrier which acts as a physical and biochemical barrier, the pro-cancerogenic and immunosuppressive tumor microenvironment and tumour characteristics like tumour volume and antigen expression. In this paper we review the data regarding the ongoing the development of ADCs in glioma patients as well as potential strategies to overcome these barriers to maximise their therapeutic potential.