Akt Inhibitor Advancements: From Capivasertib Approval to Covalent-Allosteric Promises

Akt kinase is vital in cell growth, survival, metabolism, and migration. Dysregulation of Akt signaling is implicated in cancer and metabolic disorders. In the context of cancer, overactive Akt promotes cell survival and proliferation. This has spurred extensive research into developing Akt inhibitors as potential therapeutic agents to disrupt aberrant Akt signaling. Akt inhibitors are classified into three main types: ATP-competitive, allosteric, and covalent-allosteric inhibitors (CAAIs). ATP-competitive inhibitors compete with ATP for binding to Akt, allosteric inhibitors interact with the Pleckstrin homology (PH) domain, and covalent-allosteric inhibitors form covalent bonds, making them more potent and selective. Notably, capivasertib (AZD5363), a potent ATP-competitive Akt inhibitor, received FDA approval in November 2023 for use in combination with the estrogen receptor degrader fulvestrant to treat breast cancer. Challenges remain, including improving selectivity, identifying biomarkers to tailor treatments, and enhancing therapeutic efficacy while minimizing adverse effects. Particularly covalent-allosteric inhibitors hold promise for future more effective and personalized treatments.

Anorectal and Genital Mucosal Melanoma: Diagnostic Challenges, Current Knowledge and Therapeutic Opportunities of Rare Melanomas

Mucosal melanomas (MM) are rare tumors, being less than 2% of all diagnosed melanomas, comprising a variegated group of malignancies arising from melanocytes in virtually all mucosal epithelia, even if more frequently found in oral and sino-nasal cavities, ano-rectum and female genitalia (vulva and vagina). To date, there is no consensus about the optimal management strategy of MM. Furthermore, the clinical rationale of molecular tumor characterization regarding BRAF, KIT or NRAS, as well as the therapeutic value of immunotherapy, chemotherapy and targeted therapy, has not yet been deeply explored and clearly established in MM. In this overview, focused on anorectal and genital MM as models of rare melanomas deserving of a multidisciplinary approach, we highlight the need of referring these patients to centers with experts in melanoma, anorectal and uro-genital cancers treatments. Taking into account the rarity, the poor outcomes and the lack of effective treatment options for MM, tailored research needs to be promptly promoted.

Clinical Development of AKT Inhibitors and Associated Predictive Biomarkers to Guide Patient Treatment in Cancer Medicine

The serine/threonine kinase AKT is a critical effector of the phosphoinositide 3-kinase (PI3K) signaling cascade and has a pivotal role in cell growth, proliferation, survival, and metabolism. AKT is one of the most commonly activated pathways in human cancer and dysregulation of AKT-dependent pathways is associated with the development and maintenance of a range of solid tumors. There are multiple small-molecule inhibitors targeting different components of the PI3K/AKT pathway currently at various stages of clinical development, in addition to new combination strategies aiming to boost the therapeutic efficacy of these drugs. Correlative and translational studies have been undertaken in the context of clinical trials investigating AKT inhibitors, however the identification of predictive biomarkers of response and resistance to AKT inhibition remains an unmet need. In this review, we discuss the biological function and activation of AKT, discuss its contribution to tumor development and progression, and review the efficacy and toxicity data from clinical trials, including both AKT inhibitor monotherapy and combination strategies with other agents. We also discuss the promise and challenges associated with the development of AKT inhibitors and associated predictive biomarkers of response and resistance.

Mucosal Melanoma: Pathological Evolution, Pathway Dependency and Targeted Therapy

Mucosal melanoma (MM) is a rare melanoma subtype that originates from melanocytes within sun-protected mucous membranes. Compared with cutaneous melanoma (CM), MM has worse prognosis and lacks effective treatment options. Moreover, the endogenous or exogenous risk factors that influence mucosal melanocyte transformation, as well as the identity of MM precursor lesions, are ambiguous. Consequently, there remains a lack of molecular markers that can be used for early diagnosis, and therefore better management, of MM. In this review, we first summarize the main functions of mucosal melanocytes. Then, using oral mucosal melanoma (OMM) as a model, we discuss the distinct pathologic stages from benign mucosal melanocytes to metastatic MM, mapping the possible evolutionary trajectories that correspond to MM initiation and progression. We highlight key areas of ambiguity during the genetic evolution of MM from its benign lesions, and the resolution of which could aid in the discovery of new biomarkers for MM detection and diagnosis. We outline the key pathways that are altered in MM, including the MAPK pathway, the PI3K/AKT pathway, cell cycle regulation, telomere maintenance, and the RNA maturation process, and discuss targeted therapy strategies for MM currently in use or under investigation.

Targeted therapy and immunotherapy: Emerging biomarkers in metastatic melanoma

Targeted therapy directed against oncogenic BRAF mutations and immune checkpoint inhibitors have transformed melanoma therapy over the past decade and prominently improved patient outcomes. However, not all patients will respond to targeted therapy or immunotherapy and many relapse after initially responding to treatment. This unmet need presents two major challenges. First, can we elucidate novel oncogenic drivers to provide new therapeutic targets? Second, can we identify patients who are most likely to respond to current therapeutic strategies in order to both more accurately select populations and avoid undue drug exposure in patients unlikely to respond? In an effort to evaluate the current state of the field with respect to these questions, we provide an overview of some common oncogenic mutations in patients with metastatic melanoma and ongoing efforts to therapeutically target these populations, as well as a discussion of biomarkers for response to immune checkpoint inhibitors-including tumor programmed death ligand 1 expression and the future use of neoantigens as a means of truly personalized therapy. This information is becoming important in treatment decision making and provides the framework for a treatment algorithm based on the current landscape in metastatic melanoma.

Oral MEK 1/2 Inhibitor Trametinib in Combination With AKT Inhibitor GSK2141795 in Patients With Acute Myeloid Leukemia With RAS Mutations: A Phase II Study

BACKGROUND

With proven single-agent activity and favorable toxicity profile of MEK-1/2 inhibition in advanced leukemia, investigation into combination strategies to overcome proposed resistance pathways is warranted. Resistance to MEK inhibition is secondary to upstream hyperactivation of RAS/RAF or activation of the PI3K/PTEN/AKT/mTOR pathway. This phase II multi-institution Cancer Therapy Evaluation Program-sponsored study was conducted to determine efficacy and safety of the combination of the ATP-competitive pan-AKT inhibitor GSK2141795, targeting the PI3K/AKT pathway, and the MEK inhibitor trametinib in RAS-mutated relapsed/refractory acute myeloid leukemia (AML).

PATIENTS AND METHODS

The primary objective was to determine the proportion of patients achieving a complete remission. Secondary objectives included assessment of toxicity profile and biologic effects of this combination. Twenty-three patients with RAS-mutated AML received the combination. Two dose levels were explored (dose level 1: 2 mg trametinib, 25 mg GSK2141795 and dose level 2: 1.5 mg trametinib, 50 mg GSK2141795).

RESULTS

Dose level 1 was identified as the recommended phase II dose. No complete remissions were identified in either cohort. Minor responses were recognized in 5 (22%) patients. The most common drug-related toxicities included rash and diarrhea, with dose-limiting toxicities of mucositis and colitis. Longitudinal correlative assessment of the modulation of MEK and AKT pathways using reverse phase protein array and phospho-flow analysis revealed significant and near significant down-modulation of pERK and pS6, respectively. Combined MEK and AKT inhibition had no clinical activity in patients with RAS-mutated AML.

CONCLUSION

Further investigation is required to explore the discrepancy between the activity of this combination on leukemia cells and the lack of clinical efficacy.

AKT as a Therapeutic Target for Cancer

Many cellular processes in cancer are attributed to kinase signaling networks. V-akt murine thymoma viral oncogene homolog (AKT) plays a major role in the PI3K/AKT signaling pathways. AKT is activated by PI3K or phosphoinositide-dependent kinases (PDK) as well as growth factors, inflammation, and DNA damage. Signal transduction occurs through downstream effectors such as mTOR, glycogen synthase kinase 3 beta (GSK3β), or forkhead box protein O1 (FOXO1). The abnormal overexpression or activation of AKT has been observed in many cancers, including ovarian, lung, and pancreatic cancers, and is associated with increased cancer cell proliferation and survival. Therefore, targeting AKT could provide an important approach for cancer prevention and therapy. In this review, we discuss the rationale for targeting AKT and also provide details regarding synthetic and natural AKT-targeting compounds and their associated studies.

Identification of WEE1 as a target to make AKT inhibition more effective in melanoma

AKT3 is one of the major therapeutic targets in melanoma but clinically targeting AKT3 alone seems to be an ineffective therapeutic approach. To identify unique strategies to enhance the efficacy of targeting AKT3, a screen was undertaken where AKT3 was co-targeted with a panel of kinases important in melanoma development. The screen identified WEE1 as the most potent target that when inhibited along with AKT3 would enhance the efficacy of targeting AKT3 in melanoma. RNAi mediated inhibition of AKT3 and WEE1 synergistically inhibited the viability of melanoma cells leading to a 65-75% decrease in tumor development. This approach was effective by mechanistically modulating pathways associated with the transcription factors p53 and FOXM1. Simultaneously regulating the activity of these two transcriptionally driven pathways, cooperatively deregulated cell cycle control and DNA damage repair to synergistically kill melanoma cells. This study uniquely identifies a potential approach to improve the efficacy of targeting AKT3 in melanoma.

AKT in cancer: new molecular insights and advances in drug development

The phosphatidylinositol-3 kinase (PI3K)-AKT pathway is one of the most commonly dysregulated pathways in all of cancer, with somatic mutations, copy number alterations, aberrant epigenetic regulation and increased expression in a number of cancers. The carefully maintained homeostatic balance of cell division and growth on one hand, and programmed cell death on the other, is universally disturbed in tumorigenesis, and downstream effectors of the PI3K-AKT pathway play an important role in this disturbance. With a wide array of downstream effectors involved in cell survival and proliferation, the well-characterized direct interactions of AKT make it a highly attractive yet elusive target for cancer therapy. Here, we review the salient features of this pathway, evidence of its role in promoting tumorigenesis and recent progress in the development of therapeutic agents that target AKT.