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.

The PI3K signaling pathway; from normal lymphopoiesis to lymphoid malignancies.

INTRODUCTION: As a vital mechanism of survival, lymphopoiesis requires the collaboration of different signaling molecules to orchestrate each step of cell development and maturation. The PI3K pathway is considerably involved in the maturation of lymphatic cells and therefore, its dysregulation can immensely affect human well-being and cause some of the most prevalent malignancies. As a result, studies that investigate this pathway could pave the way for a better understanding of the lymphopoiesis mechanisms, the undesired changes that lead to cancer progression, and how to design drugs to solve this issue. AREAS COVERED: The present review addresses the aforementioned aspects of the PI3K pathway and helps pave the way for future therapeutic approaches. In order to access the articles, databases such as Medicine Medline/PubMed, Scopus, Google Scholar, and Science Direct were utilized. The search formula was established by identifying main keywords including PI3K/Akt/mTOR pathway, Lymphopoiesis, Lymphoid malignancies, and inhibitors. EXPERT OPINION: The PI3K pathway is crucial for lymphocyte development and differentiation, making it a potential target for therapeutic intervention in lymphoid cancers. Studies are focused on developing PI3K inhibitors to impede the progression of hematologic malignancies, highlighting the pathway's significance in lymphoma and lymphoid leukemia.

Oral Estrogen Receptor PROTAC Vepdegestrant (ARV-471) Is Highly Efficacious as Monotherapy and in Combination with CDK4/6 or PI3K/mTOR Pathway Inhibitors in Preclinical ER+ Breast Cancer Models.

PURPOSE: Estrogen receptor (ER) alpha signaling is a known driver of ER-positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer. Combining endocrine therapy (ET) such as fulvestrant with CDK4/6, mTOR, or PI3K inhibitors has become a central strategy in the treatment of ER+ advanced breast cancer. However, suboptimal ER inhibition and resistance resulting from the ESR1 mutation dictates that new therapies are needed. EXPERIMENTAL DESIGN: A medicinal chemistry campaign identified vepdegestrant (ARV-471), a selective, orally bioavailable, and potent small molecule PROteolysis-TArgeting Chimera (PROTAC) degrader of ER. We used biochemical and intracellular target engagement assays to demonstrate the mechanism of action of vepdegestrant, and ESR1 wild-type (WT) and mutant ER+ preclinical breast cancer models to demonstrate ER degradation-mediated tumor growth inhibition (TGI). RESULTS: Vepdegestrant induced ≥90% degradation of wild-type and mutant ER, inhibited ER-dependent breast cancer cell line proliferation in vitro, and achieved substantial TGI (87%-123%) in MCF7 orthotopic xenograft models, better than those of the ET agent fulvestrant (31%-80% TGI). In the hormone independent (HI) mutant ER Y537S patient-derived xenograft (PDX) breast cancer model ST941/HI, vepdegestrant achieved tumor regression and was similarly efficacious in the ST941/HI/PBR palbociclib-resistant model (102% TGI). Vepdegestrant-induced robust tumor regressions in combination with each of the CDK4/6 inhibitors palbociclib, abemaciclib, and ribociclib; the mTOR inhibitor everolimus; and the PI3K inhibitors alpelisib and inavolisib. CONCLUSIONS: Vepdegestrant achieved greater ER degradation in vivo compared with fulvestrant, which correlated with improved TGI, suggesting vepdegestrant could be a more effective backbone ET for patients with ER+/HER2- breast cancer.

Dose optimization for cancer treatments with considerations for late-onset toxicities.

Given that novel anticancer therapies have different toxicity profiles and mechanisms of action, it is important to reconsider the current approaches for dose selection. In an effort to move away from considering the maximum tolerated dose as the optimal dose, the Food and Drug Administration Project Optimus points to the need of incorporating long-term toxicity evaluation, given that many of these novel agents lead to late-onset or cumulative toxicities and there are no guidelines on how to handle them. Numerous methods have been proposed to handle late-onset toxicities in dose-finding clinical trials. A summary and comparison of these methods are provided. Moreover, using PI3K inhibitors as a case study, we show how late-onset toxicity can be integrated into the dose-optimization strategy using current available approaches. We illustrate a re-design of this trial to compare the approach to those that only consider early toxicity outcomes and disregard late-onset toxicities. We also provide proposals going forward for dose optimization in early development of novel anticancer agents with considerations for late-onset toxicities.

Alpelisib for PIK3CA-mutated advanced gynecological cancers: First clues of clinical activity.

OBJECTIVE: Recurrent gynecological tumors (e.g., endometrial, and ovarian cancers) are incurable diseases; therefore, new treatment options are urgently needed. The PTEN-AKT-PI3K pathway is frequently altered in these tumors, representing a potential treatment target. Alpelisib is an α-specific PI3K inhibitor approved in PIK3CA-mutated advanced breast cancer. We report outcomes from a large series of patients with PIK3CA-mutated gynecological cancers prospectively treated with alpelisib within a controlled program. METHODS: From April 2021 to December 2022, 36 patients with PIK3CA-mutated advanced gynecological cancers received alpelisib 300 mg orally once daily. Objective response (ORR) and disease control (DCR) rates provided measure of the antitumor activity of alpelisib, the primary objective of the study. RESULTS: Included patients had endometrial (17/36 [47%]), ovarian (10/36 [28%]), or other gynecological cancers (9/36 [25%]). Most patients had received 2-3 prior systemic treatments (endometrial, 47·2%; ovarian, 60%; other, 56%), and presented with visceral metastases at baseline (82%, 70%, and 56%, respectively). Overall, 17 different PIK3CA mutations were found, including 53% in the kinase domain (most commonly H1047R) and 36% in the helical domain (most commonly E545K). Overall, the ORR was 28% and DCR was 61%, with the greatest benefit observed in patients with endometrial cancer (35% and 71%, respectively). CONCLUSION: Alpelisib represents an active treatment option in patients with recurrent gynecological cancers harboring a PIK3CA mutation. These findings support the need of biomarker-driven randomized trials of PI3K inhibitors in gynecological cancers.