Management Strategies for Hyperglycemia Associated with the α-Selective PI3K Inhibitor Alpelisib for the Treatment of Breast Cancer

Therapeutic management of PI3Kα inhibitor-induced hyperglycemia with a novel glucokinase activator: Advancing the Frontier of PI3Kα inhibitor therapy

OBJECTIVES

The phosphatidylinositol 3-kinase (PI3K) signaling pathway is a pivotal target in cancer treatment, driving substantial investigation into PI3K inhibitors (PI3Ki). However, the common on-target adverse effect of hyperglycemia presents a substantial challenge to their clinical application. There is an urgent need to discover an anti-hyperglycemic agent that maintains the efficacy of PI3Ki.

METHODS

We conducted a comprehensive study to explore the interaction between exogenous hyperinsulinemia and PI3Ki in SKOV3 and OVCAR3 ovarian cancer cell lines. We used Western blotting, CCK-8, and EdU assays to determine the effect of this interaction on cell proliferation. In addition, we evaluated the anti-hyperglycemic effects of dorzagliatin in a PI3Ki-induced hyperglycemic mice model. Cell line-derived xenograft (CDX) models were employed to evaluate the in vivo tumor growth inhibitory effects of combining dorzagliatin with PI3Ki.

RESULTS

Western blot analysis demonstrated that insulin activated the AKT/INSR/mTOR pathway, reversing PI3Ki-induced p-AKT inhibition. Insulin also attenuated the anti-proliferative effects of PI3Ki. In the hyperglycemic mouse model, dorzagliatin significantly reduced blood glucose levels compared to controls. The combination therapy group (Dorzagliatin + PI3Ki) in CDX models showed a marked reduction in tumor volume. Dorzagliatin not only mitigated hyperglycemia but also enhanced the anti-tumor effects of PI3Ki. A clinical trial (NCT06117566) in cervical cancer patients supported these findings, showing that dorzagliatin stabilized blood glucose levels, facilitated body weight recovery, and achieved a confirmed partial response (PR).

CONCLUSIONS

Dorzagliatin shows promise for managing PI3Ki-associated hyperglycemia, thereby enhancing its therapeutic efficacy. The activation of liver glycogen kinase and insulin regulation may be key mechanisms underlying its therapeutic benefits.

Dynamics of hyperglycemia of patients treated with alpelisib: exploratory interim analysis of ITACA trial

BACKGROUND

Alpelisib and fulvestrant combination has improved outcomes in patients with phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA)-mutated, hormone receptor-positive (HR+), human epidermal growth factor receptor 2 negative (HER2-)- advanced breast cancer (BC) who relapsed or progressed on prior endocrine therapy. Hyperglycemia, on target toxicity, is a frequent adverse event occurring in over 60% of patients.

OBJECTIVES

The ITACA trial explores whether low carbohydrate dietary modifications and evening dosing of alpelisib to potentially mitigate impact of food on hyperglycemia. This exploratory interim analysis aimed to quantify the incidence and timing of hyperglycemia in the ITACA trial's pooled sample.

METHODS

This exploratory interim analysis of the ongoing ITACA trial included 23 patients with HR+, HER2-negative metastatic BC receiving alpelisib and fulvestrant. The exploratory outcomes were grade 2-4 hyperglycemia-free survival and time to onset of hyperglycemia.

RESULTS

Most patients, 21 (91.3%), experienced any-grade hyperglycemia (Grade 1: 9 [39.1%], Grade 2: 8 [34.8%], Grade 3: 4 [17.4%], and Grade 4: 0 [0.0%]) within the first week of alpelisib initiation. The median grade 2-4 hyperglycemia-free survival was 6 days (95% CI 3; 44 days).

CONCLUSIONS

This exploratory interim analysis demonstrated the rapid onset of hyperglycemia in patients receiving alpelisib, even with the ITACA trial's dietary interventions. Proactive monitoring, within the first week after initiation of treatment, and early management of hyperglycemia are crucial in this patient population.

Understanding the conformational dynamics of PI3Kα due to helical domain mutations: insights from Markov state model analysis

Phosphoinositide 3-kinases (PI3Ks) phosphorylate phosphoinositides on the membrane, which act as secondary signals for various cellular processes. PI3Kα, a heterodimer of the p110α catalytic subunit and the p85α regulatory subunit, is activated by growth factor receptors or mutations. Among these mutations, E545K present in the helical domain is strongly associated with cancer, and is known to disrupt interactions between the regulatory and catalytic subunits, leading to its constitutive activation. However, while the mutation's role in disrupting autoinhibition is well documented, the molecular mechanisms linking this mutation in the helical domain to the structural changes in the kinase domain remain poorly understood. This study aims to understand the conformational events triggered by the E545K mutation, elucidate how these changes propagate from the helical domain to the kinase domain, and identify crucial residues involved in the activation process. Molecular dynamics (MD) simulations combined with Markov state modeling (MSM) were employed to explore the conformational landscapes of both the wild-type and mutant systems. Structural and energetic analyses, including Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) calculations, revealed that the E545K mutation significantly reduces the binding affinity between the regulatory and catalytic subunits. The mutation was found to induce a sliding motion of the regulatory subunit along the catalytic subunit, leading to the disruption of key salt-bridges between these domains. This disruption releases the inhibitory effect of the regulatory subunit, resulting in increased domain motion, particularly in the adaptor-binding domain (ABD). Enhanced flexibility in the ABD, helical, and C2 domains facilitates the rearrangement of the two lobes of kinase domain, thereby promoting activation. Additionally, the mutation appears to enhance PI3Kα's membrane affinity via the Ras-binding domain (RBD). Network analysis helped to identify key residues that may involve in allosteric signaling pathways, providing insights into the communication between domains. Druggable pockets in the metastable states were predicted followed by its docking with a PI3K inhibitor library. Docking studies revealed the crucial residues that may be participating in inhibitor binding. The identification of residues and regions involved in activation mechanisms using MSM helped to reveal the conformational events and the knowledge on probable allosteric pockets, which may be helpful in designing better therapeutics.

Alpelisib-Induced Hyperglycemia in PIK3CA+ Breast Cancer Patients

Alpelisib is a phosphatidylinositol 3-kinase inhibitor approved by the US Food and Drug Administration for the treatment of hormone receptor-positive metastatic breast cancer with PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α) mutation. In recent years a number of adverse effects have been observed to be associated with this therapy, the most notable of which is hyperglycemia. A literature search was conducted to include case studies, case series, systematic reviews, and meta-analyses within the last 10 years that evaluated patients with PIK3CA-mutated hormone receptor-positive, human epidermal growth factor receptor 2 negative metastatic breast cancer. Hyperglycemia was a notable adverse effect that was found in the majority of patients without preexisting diabetes mellitus. Patients with hyperglycemia were in the high-risk groups of advanced age, prediabetes mellitus or history of insulin resistance, increased body mass index, increased blood monocyte count, and increased hemoglobin A1c (glycated hemoglobin). Hyperglycemia was manageable with antihyperglycemic agents and dose modification/discontinuation of alpelisib with no severe progression. Other notable adverse effects were rash, stomatitis, diarrhea, pneumonitis, reduced appetite, elevated liver enzymes, nausea, fatigue, and rare reports of diabetic ketoacidosis. This literature review aims to highlight the incidence and risk factors of alpelisib-induced hyperglycemia in greater depth.

Effective Strategies for the Prevention and Mitigation of Phosphatidylinositol-3-Kinase Inhibitor-Associated Hyperglycemia: Optimizing Patient Care

Hyperglycemia is a common adverse event (AE) associated with phosphatidylinositol-3-kinase inhibitors (PI3Kis) and considered an on-target effect. Presence of hyperglycemia is associated with poor outcomes in patients with cancer, and there is need for further refinement of hyperglycemia prevention and mitigation strategies in patients receiving PI3Kis. In this review, the authors highlight effective strategies for preventing PI3Ki-induced hyperglycemia before and during treatment as well as hyperglycemia management. Prior to initiating treatment with PI3Ki, identify baseline risk factors of patients at increased risk for developing hyperglycemia, which include older age, obesity, and glycosylated hemoglobin (HbA1c) 5.7%-6.4% (prediabetes or Type 2 diabetes). To prevent new-onset hyperglycemia, optimize blood glucose, and recommend a low-carbohydrate (60-130 g/day) diet along with regular exercise to all patients prior to initiating the PI3Ki. Prophylactic metformin may be considered in all patients starting a PI3Ki with HbA1c ≤6.4%. Although existing recommendations support monitoring fasting blood glucose (FBG) once weekly (twice-weekly for intermediate-risk, daily for high-risk patients) and HbA1c every 3 months upon initiation of PI3Ki, more frequent FBG monitoring may be considered for prompt detection of hyperglycemia. Experts also recommend considering postprandial glucose monitoring because it is an early indicator of glucose intolerance. If hyperglycemia develops, metformin (first-line) and/or sodium glucose co-transporter 2 inhibitors or thiazolidinediones (second-/third-line) are the preferred agents; consider early referral to an endocrinologist. In conclusion, hyperglycemia is a common but manageable AE associated with PI3Kis. Multidisciplinary approach to the prevention, monitoring, and management of hyperglycemia optimizes patient care and allows patients to maintain therapy on PI3Ki.

Alpelisib-Induced Diabetic Ketoacidosis and Insulin-Resistant Hyperglycemia

Background/Objective

Alpelisib is a phosphatidylinositol 3-kinase inhibitor used to treat certain hormone therapy resistant breast cancers that can cause hyperglycemia through inhibition of the insulin signaling cascade. Diabetic ketoacidosis with the initiation of alpelisib remains a rare complication. The objective of this report is to describe a patient with alpelisib-induced diabetic ketoacidosis and the difficulties of management.

Case Report

A 59-year-old woman was admitted to the hospital with a history of noninsulin dependent type 2 diabetes on metformin presented with diabetic ketoacidosis. One month prior to this hospitalization, the patient was started on alpelisib. On presentation, blood glucose level was 612 mg/dL and hemoglobin A1c level was 11.9% (107 mmol/mol), a 4.6% (27 mmol/mol) increase from 2 months prior. The patient was started on intravenous insulin and alpelisib was held resulting in rapid resolution of the patient's hyperglycemia and ketoacidosis. However, with reinitiation of alpelisib the patient developed worsening hyperglycemia. Relative glycemic control was ultimately obtained with 3 oral agents and high doses of insulin.

Discussion

Direct inhibition of insulin signaling by alpelisib leads to insulin-resistant hyperglycemia. Most cases can be controlled with oral agents; however, insulin therapy is required in rare instances. Although more effective for glycemic control, insulin therapy has the potential to decrease the antitumor effects of alpelisib.

Conclusion

Diabetic ketoacidosis is a rare complication of alpelisib initiation, which is quickly resolved with cessation of the agent. For patients where cessation is not an option, insulin and insulin sensitizing agents can be used to achieve glycemic control at the potential detriment of tumor treatment.

Single Dose of Phosphatidylinositol 3-Kinase Inhibitor Alpelisib Induces Insulin Resistance in Healthy Adults: A Randomized Feasibility Study

Our objective was to test a single dose of the phosphatidylinositol 3-kinase (PI3K) inhibitor alpelisib as a tool for acute modeling of insulin resistance in healthy volunteers. This single-center double-blind phase 1 clinical trial randomly assigned healthy adults to a single oral dose of 300 mg alpelisib (n = 5) or placebo (n = 6) at bedtime, followed by measurement of glucose, insulin, and C-peptide levels after an overnight fast and during a 3-h 75-g oral glucose tolerance test (OGTT). Fasting plasma glucose trended higher with alpelisib (mean ± SD 93 ± 11 mg/dL) versus placebo (84 ± 5 mg/dL); mean fasting serum insulin increased nearly fivefold (23 ± 12 vs. 5 ± 3 μU/mL, respectively), and HOMA of insulin resistance (IR) scores were 5.4 ± 3.1 for alpelisib and 1.1 ± 0.6 for placebo. During OGTT, incremental area under the curve (AUC) for insulin was more than fourfold greater with alpelisib (22 ± 15 mU/mL × min) than with placebo (5 ± 2 mU/mL × min); glucose AUC trended higher with alpelisib. Single-dose alpelisib was well tolerated and produced metabolic alterations consistent with acute induction of IR, validating its use for mechanistic study of insulin action in humans.

ARTICLE HIGHLIGHTS

Hyperglycemia secondary to phosphatidylinositol-3 kinase (PI3K) inhibition

Summary

Phosphatidylinositol-3 kinase (PI3K) is a critical intracellular pathway that regulates cell growth, metabolism, and survival and has been implicated in most human cancers. Targeting this pathway has been approved as a therapeutic option for breast cancer and lymphoma (e.g. alpelisib, idelalisib), and there are several clinical trials underway in additional types of cancer. However, PI3K is an important mediator of the action of insulin, and the use of PI3K inhibitors has been associated with hyperglycemia. We report the case of a 53-year-old female with metastatic breast cancer who developed acute grade 3 hyperglycemia from a novel PI3K inhibitor, inavolisib. We review the treatment options for PI3K inhibitor-associated hyperglycemia. Treatment strategies that minimize hyperinsulinemia may be preferable considering animal models have demonstrated that hyperinsulinemia may result in partial reactivation of the PI3K pathway and counter the anti-cancer effectiveness of PI3K inhibitors.

Learning points

Phosphatidylinositol-3 kinase (PI3K) is an intracellular pathway that regulates a range of physiological functions, including cell growth, metabolism, survival, and angiogenesis. Hyperactivation of the PI3K pathway is associated with almost all human cancers, and thus PI3K inhibition has been proposed as a treatment option for selected cancers. The action of insulin after binding to the insulin receptor on the cell surface (e.g. glucose uptake in skeletal muscle, inhibition of glycogenolysis and gluconeogenesis) is mediated by the intracellular PI3K pathway, and thus PI3K inhibition may lead to hyperinsulinemic hyperglycemia. All patients treated with PI3K inhibitors should receive pre-treatment screening for hyperglycemia, lifestyle advice, and a glucometer to measure fasting BGL and 2-h post-dinner BGL levels twice per week for at least the first 30 days of treatment. Insulin or insulin secretagogues (e.g. sulfonylurea) may inhibit the anti-tumor activity of PI3K inhibitors, and thus treatment of PI3K inhibitor-associated hyperglycemia should prefer alternative approaches such as a low carbohydrate diet, metformin, SGLT2i, or dose reduction of the PI3K inhibitor.

Quantitative evaluation of the efficacy and safety profiles of two types of targeted inhibitors combined with endocrine therapy in ER+/HER2- metastatic breast cancer

PURPOSE

The aim of this study was to quantitatively compare the efficacy and safety of CDK4/6 inhibitors and PI3K/AKT/mTOR inhibitors for ER+/HER2- metastatic breast cancer.

METHODS

A parametric survival function was used to analyze the time course of overall survival (OS) and progression-free survival (PFS). The objective response rate (ORR) and the incidence of any grade and grade 3-4 adverse events were summarized using the random-effects model of a single-arm meta-analysis.

RESULTS

This study included 44 arms from 48 publications, with a total sample size of 7881 patients. Our study revealed that CDK4/6 inhibitors had a median OS of 40.7 months, a median PFS of 14.8 months, and an ORR of 40%, whereas PI3K/AKT/mTOR inhibitors had a median OS of 29.8 months, a median PFS of 8.3 months, and an ORR of 20%. Additionally, this study also found that the proportion of patients with visceral metastases and specific endocrine therapy used in combination significantly impact OS and PFS. In terms of adverse events, CDK4/6 inhibitors exhibited a relatively high incidence of hematological adverse events.

CONCLUSION

Our study provides solid quantitative evidence for the first-line recommendation of CDK4/6 inhibitors combined with endocrine therapy for ER+/HER2- metastatic breast cancer in clinical guidelines.

Overcoming Resistance in Cancer Therapy: Computational Exploration of PIK3CA Mutations, Unveiling Novel Non-Toxic Inhibitors, and Molecular Insights Into Targeting PI3Kα

Phosphoinositide-3-kinases (PI3 K) are pivotal regulators of cell signaling implicated in various cancers. Particularly, mutations in the PIK3CA gene encoding the p110α catalytic subunit drive oncogenic signaling, making it an attractive therapeutic target. Our study conducted in silico exploration of 31 PIK3CA mutations across breast, endometrial, colon, and ovarian cancers, assessing their impacts on response to PI3Kα inhibitors and identifying potential non-toxic inhibitors and also elucidating their effects on protein stability and flexibility. Specifically, we observed significant alterations in the stability and flexibility of the PI3 K protein induced by these mutations. Through molecular docking analysis, we evaluated the binding interactions between the selected inhibitors and the PI3 K protein. The filtration of ligands involved calculating chemical descriptors, incorporating Veber and Lipinski rules, as well as IC50 values and toxicity predictions. This process reduced the initial dataset of 1394 ligands to 12 potential non-toxic inhibitors, and four reference inhibitors with significant biological activity in clinical trials were then chosen based on their physico-chemical properties. This analysis revealed Lig5's exceptional performance, exhibiting superior affinity and specificity compared to established reference inhibitors such as pictilisib. Lig5 formed robust binding interactions with the PI3 K protein, suggesting its potential as a highly effective therapeutic agent against PI3 K-driven cancers. Furthermore, molecular dynamics simulations provided valuable insights into Lig5's stability and its interactions with PI3 K over 100 ns. These simulations supported Lig5's potential as a versatile inhibitor capable of effectively targeting various mutational profiles of PI3 K, thereby mitigating issues related to resistance and toxicity commonly associated with current inhibitors.

Zirconium Hydride Catalysis Initiated by Tetrabutylammonium Fluoride

In our drug discovery campaigns to target the oncogenic drivers of cancers, the demand for a chemoselective, stereoselective and economical synthesis of chiral benzylamines drove the development of a catalytic zirconium hydride reduction. This methodology uses the inexpensive, bench stable zirconocene dichloride, and a novel tetrabutylammonium fluoride activation tactic to catalytically generate a metal hydride under ambient conditions. The diastereo- and chemoselectivity of this reaction was tested with the preparation of key intermediates from our discovery programs and in the scope of sulfinyl ketimines and carbonyls relevant to medicinal chemistry and natural product synthesis. A preliminary mechanistic investigation conducted into the role of tetrabutylammonium fluoride indicates that formation of a zirconocene fluoride occurs to initiate catalysis. The implications of this convenient activation approach may provide expanded roles for zirconium hydrides in catalytic transformations.

A deep learning-based theoretical protocol to identify potentially isoform-selective PI3Kα inhibitors

Phosphoinositide 3-kinase alpha (PI3Kα) is one of the most frequently dysregulated kinases known for their pivotal role in many oncogenic diseases. While the side effects linked to existing drugs against PI3Kα-induced cancers provide an avenue for further research, the significant structural conservation among PI3Ks makes it extremely difficult to develop new isoform-selective PI3Kα inhibitors. Embracing this challenge, we herein designed a hybrid protocol by integrating machine learning (ML) with in silico drug-designing strategies. A deep learning classification model was developed and trained on the physicochemical descriptors data of known PI3Kα inhibitors and used as a screening filter for a database of small molecules. This approach led us to the prediction of 662 compounds showcasing appropriate features to be considered as PI3Kα inhibitors. Subsequently, a multiphase molecular docking was applied to further characterize the predicted hits in terms of their binding affinities and binding modes in the targeted cavity of the PI3Kα. As a result, a total of 12 compounds were identified whereas the best poses highlighted the efficiency of these ligands in maintaining interactions with the crucial residues of the protein to be targeted for the inhibition of associated activity. Notably, potential activity of compound 12 in counteracting PI3Kα function was found in a previous in vitro study. Following the drug-likeness and pharmacokinetic characterizations, six compounds (compounds 1, 2, 3, 6, 7, and 11) with suitable ADME-T profiles and promising bioavailability were selected. The mechanistic studies in dynamic mode further endorsed the potential of identified hits in blocking the ATP-binding site of the receptor with higher binding affinities than the native inhibitor, alpelisib (BYL-719), particularly the compounds 1, 2, and 11. These outcomes support the reliability of the developed classification model and the devised computational strategy for identifying new isoform-selective drug candidates for PI3Kα inhibition.

Four-month-old with severe PIK3CA-related overgrowth spectrum disorder successfully treated with alpelisb

PIK3CA-related overgrowth spectrum (PROS) encompasses different clinical entities caused by somatic activating mutations in PIK3CA. Among PROS, CLOVES syndrome represents a severe phenotype with poor survival rate. We present the case of a 4-month-old girl with CLOVES syndrome successfully treated with alpelisib, a PIKC3A inhibitor.

Alpelisib-Induced Diabetic Ketoacidosis: A Pharmacovigilance Analysis of the FDA Adverse Event Reporting System and Review of the Literature

BACKGROUND

Alpelisib is a PI3K inhibitor indicated with fulvestrant for treatment of advanced or metastatic hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, PIK3CA-mutated breast cancer. In the phase III SOLAR-1 trial, grade 3/4 hyperglycemic events were reported in 36.6% of patients receiving alpelisib-fulvestrant compared to 0.7% receiving placebo-fulvestrant. As case reports of diabetic ketoacidosis (DKA) have been associated with alpelisib use, the goal of this study was to characterize the FAERS reported cases of this severe adverse effect.

METHODS

A retrospective disproportionality analysis was performed using the FAERS database by calculating the reporting odds ratio (ROR) of DKA events with alpelisib from 2019 to 2022. A PubMed literature review of case reports characterizing alpelisib-induced DKA was performed.

RESULTS

Pharmacovigilance database analysis revealed significance in reporting among 87 DKA cases with alpelisib (ROR 9.84, 95% confidence interval 7.3-13.2), including hospitalization and death as reported outcomes. Review of 11 published case reports reveals median onset of DKA at 14 days with successful rechallenge possible.

CONCLUSION

Significant association with reporting exists between DKA and alpelisib exposure. We observed similar median time to onset of hyperglycemia between our analysis compared to that reported in SOLAR-1. Considering early onset of this toxicity, it is imperative that patients be closely monitored when initiating alpelisib. Addition of a preemptive antihyperglycemic or escalation in those previously on antihyperglycemic medications is beneficial in decreasing the severity of hyperglycemia with alpelisib. Further study investigating risk factors is warranted to better elucidate which patients require preemptive therapy.

Discovery and Clinical Proof-of-Concept of RLY-2608, a First-in-Class Mutant-Selective Allosteric PI3Kα Inhibitor That Decouples Antitumor Activity from Hyperinsulinemia

PIK3CA (PI3Kα) is a lipid kinase commonly mutated in cancer, including ∼40% of hormone receptor-positive breast cancer. The most frequently observed mutants occur in the kinase and helical domains. Orthosteric PI3Kα inhibitors suffer from poor selectivity leading to undesirable side effects, most prominently hyperglycemia due to inhibition of wild-type (WT) PI3Kα. Here, we used molecular dynamics simulations and cryo-electron microscopy to identify an allosteric network that provides an explanation for how mutations favor PI3Kα activation. A DNA-encoded library screen leveraging electron microscopy-optimized constructs, differential enrichment, and an orthosteric-blocking compound led to the identification of RLY-2608, a first-in-class allosteric mutant-selective inhibitor of PI3Kα. RLY-2608 inhibited tumor growth in PIK3CA-mutant xenograft models with minimal impact on insulin, a marker of dysregulated glucose homeostasis. RLY-2608 elicited objective tumor responses in two patients diagnosed with advanced hormone receptor-positive breast cancer with kinase or helical domain PIK3CA mutations, with no observed WT PI3Kα-related toxicities.

SIGNIFICANCE

Treatments for PIK3CA-mutant cancers are limited by toxicities associated with the inhibition of WT PI3Kα. Molecular dynamics, cryo-electron microscopy, and DNA-encoded libraries were used to develop RLY-2608, a first-in-class inhibitor that demonstrates mutant selectivity in patients. This marks the advance of clinical mutant-selective inhibition that overcomes limitations of orthosteric PI3Kα inhibitors. See related commentary by Gong and Vanhaesebroeck, p. 204 . See related article by Varkaris et al., p. 227 . This article is featured in Selected Articles from This Issue, p. 201.

Molecular Targeting of the Phosphoinositide-3-Protein Kinase (PI3K) Pathway across Various Cancers

The dysregulation of the phosphatidylinositol-3-kinase (PI3K) pathway can lead to uncontrolled cellular growth and tumorigenesis. Targeting PI3K and its downstream substrates has been shown to be effective in preclinical studies and phase III trials with the approval of several PI3K pathway inhibitors by the Food and Drug Administration (FDA) over the past decade. However, the limited clinical efficacy of these inhibitors, intolerable toxicities, and acquired resistances limit the clinical application of PI3K inhibitors. This review discusses the PI3K signaling pathway, alterations in the PI3K pathway causing carcinogenesis, current and novel PI3K pathway inhibitors, adverse effects, resistance mechanisms, challenging issues, and future directions of PI3K pathway inhibitors.

Feasibility and metabolic outcomes of a well-formulated ketogenic diet as an adjuvant therapeutic intervention for women with stage IV metastatic breast cancer: The Keto-CARE trial

PURPOSE

Ketogenic diets may positively influence cancer through pleiotropic mechanisms, but only a few small and short-term studies have addressed feasibility and efficacy in cancer patients. The primary goals of this study were to evaluate the feasibility and the sustained metabolic effects of a personalized well-formulated ketogenic diet (WFKD) designed to achieve consistent blood beta-hydroxybutyrate (βHB) >0.5 mM in women diagnosed with stage IV metastatic breast cancer (MBC) undergoing chemotherapy.

METHODS

Women (n = 20) were enrolled in a six month, two-phase, single-arm WFKD intervention (NCT03535701). Phase I was a highly-supervised, ad libitum, personalized WFKD, where women were provided with ketogenic-appropriate food daily for three months. Phase II transitioned women to a self-administered WFKD with ongoing coaching for an additional three months. Fasting capillary βHB and glucose were collected daily; weight, body composition, plasma insulin, and insulin resistance were collected at baseline, three and six months.

RESULTS

Capillary βHB indicated women achieved nutritional ketosis (Phase I mean: 0.8 mM (n = 15); Phase II mean: 0.7 mM (n = 9)). Body weight decreased 10% after three months, primarily from body fat. Fasting plasma glucose, plasma insulin, and insulin resistance also decreased significantly after three months (p < 0.01), an effect that persisted at six months.

CONCLUSIONS

Women diagnosed with MBC undergoing chemotherapy can safely achieve and maintain nutritional ketosis, while improving body composition and insulin resistance, out to six months.

Incidence, risk factors, and management of alpelisib-associated hyperglycemia in metastatic breast cancer

PURPOSE

The combination of fulvestrant with alpelisib, a PI3K inhibitor, improves progression-free survival in metastatic hormone receptor-positive, PIK3CA-mutant breast cancer. This study describes the incidence, risk factors, and treatment of alpelisib-associated hyperglycemia.

METHODS

Patients with metastatic breast cancer who received alpelisib from 2013 to 2021 at Memorial Sloan Kettering Cancer Center were included in this retrospective study. Alpelisib prescription dates and patient/tumor characteristics were abstracted from medical records. Risk factors associated with hyperglycemia and alpelisib dose reduction/discontinuation were evaluated using Pearson's χ2 tests.

RESULTS

Among 247 patients, baseline median body mass index was 25.4 kg/m2 and median hemoglobin A1c (HbA1c) was 5.5%. A total of 152 patients (61.5%) developed any-grade hyperglycemia and 72 patients (29.2%) developed grade 3-4 hyperglycemia; median time to onset was 16 days. A total of 100 patients (40.5%) received alpelisib on a clinical trial; rates of hyperglycemia were significantly higher in patients treated as standard care versus on a clinical trial (any-grade hyperglycemia 80.3% vs. 34.0%, grade 3-4 hyperglycemia 40.2% vs. 13.0%, p < .001). Baseline HbA1c was significantly associated with development of hyperglycemia (p < .001) and alpelisib dose reduction/discontinuation (p = .015). Among those who developed hyperglycemia, 101 (40.9%) received treatment, most commonly with metformin. A total of 49 patients (19.8%) were referred to an endocrinologist, which was associated with SGLT2 inhibitor prescription (p = .007).

CONCLUSIONS

Rates of hyperglycemia among patients treated with alpelisib as standard care were significantly higher than patients treated on clinical trials. Elevated baseline HbA1c is associated with alpelisib-induced hyperglycemia and requiring dose modification. Optimization of glycemic status before alpelisib initiation should become routine practice.

On-Target Side Effects of Targeted Therapeutics of Cancer

The concept of precision medicine is based on the identification of hallmarks of cancer to exploit them as drug targets. The basic idea was that in this way the therapeutic modalities will be more effective and the side effects will be less. Since the majority of these novel modalities are not specific for a cancer-related biological process or a cancer-specific (mutant) target protein, it is not a surprise that we had to learn new type of side effects, because these therapeutics also affect physiological or pathological processes. Even more, in cases of some of these novel therapies we were able to discover new molecular mechanisms of physiological and pathological processes. Identification of the on-target side effects of targeted drugs can help to prevent the development of them or better manage the patients when emerge during cancer therapy.

CDK4/6 inhibitors versus PI3K/AKT/mTOR inhibitors in women with hormone receptor-positive, HER2-negative metastatic breast cancer: An updated systematic review and network meta-analysis of 28 randomized controlled trials

Background

Updated evidence was required to compare the efficacy and safety of cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) inhibitors for patients with hormone receptor-positive and HER2-negative metastatic breast cancer.

Methods

A systematic review and network meta-analysis was conducted utilizing data from randomized controlled trials (RCTs) that contained interventions of CDK4/6 inhibitors or PI3K/AKT/mTOR inhibitors. Progression-free survival (PFS), overall survival (OS), and treatment-related adverse events (TRAEs) were primary outcomes of interest. Pooled hazard ratios (HRs) and odds ratios (ORs) with 95% credible intervals (CrIs) were used to assess the survival outcomes and safety profiles, respectively.

Results

A total of 28 RCTs with 12,129 participants were included. Pooled analysis showed that CDK4/6 inhibitors significantly prolonged PFS than PI3K/AKT/mTOR inhibitors (HR, 0.81; 95% CrI, 0.69–0.94), whereas no significant differences were detected regarding OS. After balancing the treatment lines and metastatic sites, the superiority of CDK4/6 inhibitors only appeared in the visceral and non-visceral subgroups. Among CDK4/6 inhibitors, abemaciclib was significantly better than others in ≥3 grade neutropenia (OR, 0.04; 95% CrI, 0.01–0.15). The incidence of stomatitis and digestive disorders was different among diverse kinds of PI3K/AKT/mTOR inhibitors. Discrepancies appeared regarding TRAEs of hepatotoxicity, diarrhea, and hyperglycemia among different interventions.

Conclusions

CDK4/6 inhibitors showed better efficacy in PFS, but the benefits disappeared when taking treatment line into consideration. Specific and discrepant safety profiles were found in two categories of agents.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42022321172.