Activity of the Gamma Secretase Inhibitor AL101 in Desmoid Tumors: A Case Report of 2 Adult Cases

Desmoid-type fibromatosis: Current therapeutic strategies and future perspectives

Desmoid tumors (DT) are rare, slow-growing, locally invasive soft tissue tumors that often pose significant therapeutic challenges. Traditional management strategies including active surveillance, surgery, radiotherapy, and systemic therapy which are associated with varying recurrence rates and high morbidity. Given the challenging nature of DT and the modest outcomes associated with current treatment strategies, there has been a growing interest in the field of γ-secretase inhibitors as a result of its action on the Wnt/β-catenin signaling pathway. In this review article, we will shed the light on the pathogenesis and molecular biology of DT, discuss its symptoms and diagnosis, and provide a comprehensive review of the traditional therapeutic approaches. We will also delve into the mechanisms of action of γ-secretase inhibitors, its efficacy, and the existing preclinical and clinical data available to date on the use of these agents, as well as the potential challenges and future prospects in the treatment landscape of these tumors.

The Notch signaling pathway in desmoid tumor: Recent advances and the therapeutic prospects

Desmoid tumor (DT) is a rare fibroblastic soft-tissue neoplasm that is characterized by local aggressiveness but no metastatic potential. Although the prognosis is relatively favorable, the unpredictable disease course and infiltrative growth lead to significant impairments and morbidity. Aberrant activation of Wnt/β-catenin signaling has been well-established in the pathogenesis of sporadic DT and familial adenomatous polyposis (FAP) or Gardners syndrome-associated DT, suggesting therapy targeting this pathway is an appealing treatment strategy. However, agents against this pathway are currently in their preliminary stages and have not yet been implemented in clinical practice. Increasing studies demonstrate activation of the Notch pathway is closely associated with the development and progression of DT, which provides a potential alternative therapeutic target against DT. Early-stage clinical trials and preclinical models have indicated that inhibition of Notch pathway might be a promising treatment approach for DT. The Notch signaling activation is mainly dependent on the activity of the γ-secretase enzyme, which is responsible for cleaving the Notch intracellular domain and facilitating its nuclear translocation to promote gene transcription. Two γ-secretase inhibitors called nirogacestat and AL102 are currently under extensive investigation in the advanced stage of clinical development. The updated findings from the phase III randomized controlled trial (DeFi trial) demonstrated that nirogacestat exerts significant benefits in terms of disease control and symptom resolution in patients with progressive DT. Therefore, this review provides a comprehensive overview of the present understanding of Notch signaling in the pathogenesis of DT, with a particular emphasis on the prospective therapeutic application of γ-secretase inhibitors in the management of DT.

Efficacy and safety of compassionate use for rare diseases: a scoping review from 1991 to 2022

BACKGROUND

Compassionate use is a system that provides patients with expedited access to drugs which has not yet been approved, but currently in clinical trials. The investigational drugs have been authorized for compassionate use in cases involving patients suffered from life-threatening diseases and with no alternative treatments. For instance, patients afflicted with highly heterogeneous rare diseases are eligible for treatment assistance through the compassionate use program. This study aims to investigate the characteristics of compassionate use in the context of rare diseases, evaluate the efficacy and safety of compassionate use for rare diseases, and analyze the marketing approval of investigational drugs.

METHODS

The case reports/case series of compassionate use were collected by conducting searches on Embase, PubMed, Web of Science, CNKI and SinoMed, spanning from January 1991 to December 2022. Subsequently, two independent reviewers evaluated these reports. Case reports/case series that met the inclusion criteria and exclusion criteria were enrolled. Information extracted from these reports and series included patients' basic information, the investigational drug's name, its indication, adverse events, treatment outcomes, and other relevant data.

RESULTS

A total of forty-six studies were included, encompassing 2079 patients with an average age of 38.1 years. Thirty-nine different drugs were involved in 46 studies. Furthermore, neoplasms emerged as the most common therapeutic area for compassionate use in rare disease management (23/46, 50.0%). Regarding the treatment efficacy, four studies reported successful disease resolution, while 35 studies observed symptom improvement among patients. Conversely, four studies documented no significant effects on patients' diseases. Moreover, one study reported worsened results following compassionate use, while the efficacy was not described in 2 studies. Adverse events were reported in 31 studies (67.4%) because of the compassionate use, while no adverse events occurred in 13 studies (28.3%). In other 2 studies, there was no description about whether treatment-emergent adverse events (TEAEs) were happened. 136 patients (6.5%) had Grade 5 adverse events (death), of which 19 deaths (0.9%) were considered to be related to compassionate use. Furthermore, the investigational drugs in 33 studies (33/46, 71.7%) received new drug approval at the end of January 31, 2023.The time lag from the start of the compassionate use to the formal approval of the investigational drug was 790.5 (IQR 359-2199.3) days. We found that in 11 studies, encompassing 9 different drugs, some compassionate use indications had not received regulatory authorities at the end of January 31, 2023.

CONCLUSION

The current status of compassionate use for rare diseases was clarified systematically in this study. Compassionate use of investigational drug is a significant treatment option for rare disease. In general, compassionate use appears to demonstrate favorable efficacy in the context of rare diseases, with a significant proportion of compassionate use drugs subsequently receiving marketing approval. However, the safety of drugs for compassionate use cannot be fully evaluated due to the safety data were not covered in some enrolled studies. Therefore, the establishment of an adverse event reporting system specific to compassionate use is warranted.

Modulation of Notch Signaling by Small-Molecular Compounds and Its Potential in Anticancer Studies

Notch signaling is responsible for conveying messages between cells through direct contact, playing a pivotal role in tissue development and homeostasis. The modulation of Notch-related processes, such as cell growth, differentiation, viability, and cell fate, offer opportunities to better understand and prevent disease progression, including cancer. Currently, research efforts are mainly focused on attempts to inhibit Notch signaling in tumors with strong oncogenic, gain-of-function (GoF) or hyperactivation of Notch signaling. The goal is to reduce the growth and proliferation of cancer cells, interfere with neo-angiogenesis, increase chemosensitivity, potentially target cancer stem cells, tumor dormancy, and invasion, and induce apoptosis. Attempts to pharmacologically enhance or restore disturbed Notch signaling for anticancer therapies are less frequent. However, in some cancer types, such as squamous cell carcinomas, preferentially, loss-of-function (LoF) mutations have been confirmed, and restoring but not blocking Notch functions may be beneficial for therapy. The modulation of Notch signaling can be performed at several key levels related to NOTCH receptor expression, translation, posttranslational (proteolytic) processing, glycosylation, transport, and activation. This further includes blocking the interaction with Notch-related nuclear DNA transcription. Examples of small-molecular chemical compounds, that modulate individual elements of Notch signaling at the mentioned levels, have been described in the recent literature.

Targeted therapies for the treatment of soft tissue sarcoma

Soft tissue sarcomas are rare malignant tumors derived from mesenchymal cells that have a high morbidity and mortality related to frequent occurrence of advanced and metastatic disease. Over the past two decades there have been significant advances in the use of targeted therapies for the treatment of soft tissue sarcoma. The ability to study various cellular markers and pathways related to sarcomagenesis has led to the creation and approval of multiple novel therapies. Herein, we describe the current landscape of targeted medications used in the management of advanced or metastatic soft tissue sarcomas, excluding GIST. We distinguish three categories: targeted therapies that have current US Food and Drug Administration (FDA) approval for treatment of soft tissue sarcoma, non-FDA approved targeted therapies, and medications in development for treatment of patients with soft tissue sarcoma.

Targeting the DLL/Notch Signaling Pathway in Cancer: Challenges and Advances in Clinical Development

The DLL/Notch signaling pathway plays an important role in cancer as a key driver in maintaining cancer stemness and inducing tumor angiogenesis. Many different types of DLL/Notch inhibitors have been developed and explored in clinical trials for cancer treatment, including small-molecule compounds to inhibit gamma-secretase and antibodies targeting Notch ligands or receptors. Despite promising efficacy of these inhibitors in preclinical studies, the overall clinical outcomes have been insufficient to advance to the next stage of clinical development primarily due to safety concerns or modest efficacy. To overcome the narrow therapeutic window of DLL/Notch inhibitors, diverse strategies for improving the balance between the safety and efficacy are currently being explored. Here, we review the clinical perspective and potential of DLL/Notch inhibitors as anticancer agents based on recent results from multiple clinical studies. An antibody specifically targeting Notch ligands or receptors may offer a better approach to reduce concerns about toxicity derived from broad-spectrum DLL/Notch blockers. In addition, combination therapy with an angiogenesis inhibitor targeting VEGF could be a better option for increasing anticancer efficacy. Taken together, the results of clinical trials suggest a bispecific antibody blocking the DLL/Notch and VEGF/VEGFR signaling pathways as a promising approach for effective anticancer treatment.

Signaling pathways in the regulation of cancer stem cells and associated targeted therapy

Cancer stem cells (CSCs) are defined as a subpopulation of malignant tumor cells with selective capacities for tumor initiation, self-renewal, metastasis, and unlimited growth into bulks, which are believed as a major cause of progressive tumor phenotypes, including recurrence, metastasis, and treatment failure. A number of signaling pathways are involved in the maintenance of stem cell properties and survival of CSCs, including well-established intrinsic pathways, such as the Notch, Wnt, and Hedgehog signaling, and extrinsic pathways, such as the vascular microenvironment and tumor-associated immune cells. There is also intricate crosstalk between these signal cascades and other oncogenic pathways. Thus, targeting pathway molecules that regulate CSCs provides a new option for the treatment of therapy-resistant or -refractory tumors. These treatments include small molecule inhibitors, monoclonal antibodies that target key signaling in CSCs, as well as CSC-directed immunotherapies that harness the immune systems to target CSCs. This review aims to provide an overview of the regulating networks and their immune interactions involved in CSC development. We also address the update on the development of CSC-directed therapeutics, with a special focus on those with application approval or under clinical evaluation.

Molecular pathogenesis of desmoid tumor and the role of γ-secretase inhibition

Desmoid tumor (DT) is a rare, soft tissue neoplasm associated with an unpredictable clinical course. Although lacking metastatic potential, DT is often locally aggressive and invasive, causing significant morbidity. Both sporadic DT and familial adenomatous polyposis (FAP)-associated DT are linked to constitutive activation of the Wnt signaling pathway with mutations in the β-catenin oncogene CTNNB1 or the tumor suppressor gene APC, respectively. Cross-talk between the Notch and Wnt pathways, as well as activation of the Notch pathway resulting from dysregulation of the Wnt pathway, suggest a possible therapeutic target for DT. Due to the role γ-secretase plays in Notch signaling through cleavage of the Notch intracellular domain (with subsequent translocation to the nucleus to activate gene transcription), γ-secretase inhibitors (GSIs) have emerged as a potential treatment for DT. Two GSIs, nirogacestat (PF-03084014) and AL102 are in later-stage clinical development; nirogacestat is being evaluated in a phase 3, randomized, placebo-controlled trial while AL102 is being evaluated in a phase 2/3, dose-finding (part A) and placebo-controlled (part B) trial. This review summarizes current understanding of the molecular pathogenesis of DT focusing on dysregulation of the Wnt signaling pathway, crosstalk with the Notch pathway, and the potential therapeutic role for GSIs in DT.

Evolving strategies for management of desmoid tumor

Desmoid tumors (DTs) are rare soft tissue mesenchymal neoplasms that may be associated with impairments, disfigurement, morbidity, and (rarely) mortality. DT disease course can be unpredictable. Most DTs are sporadic, harboring somatic mutations in the gene that encodes for β-catenin, whereas DTs occurring in patients with familial adenomatous polyposis have germline mutations in the APC gene, which encodes for a protein regulator of β-catenin. Pathology review by an expert soft tissue pathologist is critical in making a diagnosis. Magnetic resonance imaging is preferred for most anatomic locations. Surgery, once the standard of care for initial treatment of DT, is associated with a significant risk of recurrence as well as avoidable morbidity because spontaneous regressions are known to occur without treatment. Consequently, active surveillance in conjunction with pain management is now recommended for most patients. Systemic medical treatment of DT has evolved beyond the use of hormone therapy, which is no longer routinely recommended. Current options for medical management include tyrosine kinase inhibitors as well as more conventional cytotoxic chemotherapy (e.g., anthracycline-based or methotrexate-based regimens). A newer class of agents, γ-secretase inhibitors, appears promising, including in patients who fail other therapies, but confirmation in Phase 3 trials is needed. In summary, DTs present challenges to physicians in diagnosis and prognosis, as well as in determining treatment initiation, type, duration, and sequence. Accordingly, evaluation by a multidisciplinary team with expertise in DT and patient-tailored management are essential. As management strategies continue to evolve, further studies will help clarify these issues and optimize outcomes for patients.

Notch signaling in malignant gliomas: supporting tumor growth and the vascular environment

Glioblastoma is the most malignant form of glioma, which is the most commonly occurring tumor of the central nervous system. Notch signaling in glioblastoma is considered to be a marker of an undifferentiated tumor cell state, associated with tumor stem cells. Notch is also known for facilitating tumor dormancy escape, recurrence and progression after treatment. Studies in vitro suggest that reducing, removing or blocking the expression of this gene triggers tumor cell differentiation, which shifts the phenotype away from stemness status and consequently facilitates treatment. In contrast, in the vasculature, Notch appears to also function as an important receptor that defines mature non-leaking vessels, and increasing its expression promotes tumor normalization in models of cancer in vivo. Failures in clinical trials with Notch inhibitors are potentially related to their opposing effects on the tumor versus the tumor vasculature, which points to the need for a greater understanding of this signaling pathway.