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Endocrine therapy is one of the key and most frequently utilized strategies for breast cancer treatment, both in the early and advanced stages of the disease. Its activity relies on the presence of functional estrogen receptors in cancer cells, which are responsible for stimulating the survival and growth of breast cancer. Over the past four decades, endocrine therapy significantly has progressed not only due to the emergence of new drugs disrupting the estrogen receptor functions but also thanks to the development of new targeted agents that block intracellular mechanisms of hormone resistance. The large number of endocrine therapies used either as monotherapy or in combination with other agents vary not only in their mechanisms of action but also their safety profiles. This diversity poses a big and continuously growing challenge in planning and conducting an optimal, multi-stage palliative hormonal treatment in clinical practice. This article aims to summarize current knowledge on contemporary endocrine treatment options and highlight the possibilities for making hormone therapies a truly personalized treatment for advanced breast cancer patients. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Recurrent squamous cell carcinoma (SCC) of the head and neck (SCCHN) remains a formidable clinical challenge despite available treatments. The phosphatidylinositol 3‐kinase (PI3K) pathway has been identified as a potential therapeutic target, and alpelisib, a selective PI3Kα inhibitor, has demonstrated efficacy in certain malignancies. Combining this targeted therapy with immunotherapy has been suggested in previous studies as a promising strategy to bolster the immune response against cancer. Cases A 69‐year‐old woman with locoregional recurrence of PIK3CA‐mutated SCC of the left maxilla and cervical nodal metastases. Several chemotherapeutic regimens, including cisplatin, docetaxel, 5FU, chemoradiotherapy, and mono‐immunotherapy, resulted in disease progression. Alpelisib combined with pembrolizumab led to a sustained response for 9 months. A 58‐year‐old man with recurrent metastatic PIK3CA‐mutated SCC of the oropharynx, involving the left lung, hilar, and mediastinal lymph nodes. Despite prior palliative radiation and platinum‐based chemotherapy with pembrolizumab and cetuximab, treatment with alpelisib and nivolumab resulted in a partial response. Severe hyperglycemia and rash led to treatment discontinuation. Conclusion Our findings highlight the potential of this innovative therapeutic combination, suggesting a need for further investigations in this setting.

Genetic alterations of the PIK3CA gene, encoding the p110α catalytic subunit of PI3Kα enzyme, are found in a broad spectrum of human cancers. Many cancer-associated PIK3CA mutations occur at 3 hotspot locations and are termed canonical mutations. Canonical mutations result in hyperactivation of PI3K and promote oncogenesis via the PI3K/AKT/mTOR and PI3K/COX-2/PGE2 signaling pathways. These mutations also may serve as predictive biomarkers of response to PI3K inhibitors, as well as NSAID therapy. A large number of non-canonical PIK3CA mutations have also been identified in human tumors, but their functional properties are poorly understood. Here we review the landscape of PIK3CA mutations in different cancers and efforts underway to define the functional properties of non-canonical PIK3CA mutations. In addition, we summarize what has been learned from clinical trials of PI3K inhibitors as well as current trials incorporating these molecular targeting agents.

PurposeThe oral, α-specific phosphatidylinositol-3-kinase (PI3Kα) inhibitor alpelisib is the first PI3K inhibitor approved for the treatment of advanced breast cancer. As alpelisib is a relatively new therapeutic option, specific guidance and a multidisciplinary approach are needed to provide optimal patient care. The primary objective of this manuscript is to provide comprehensive guidance on minimizing and managing adverse events (AEs) for patients with advanced breast cancer who are receiving alpelisib.MethodsClinical studies, prescribing information, published literature, and relevant guidelines were reviewed to provide recommendations on the prevention and management of alpelisib-associated AEs.ResultsThe most common AEs associated with alpelisib in the phase 3 SOLAR-1 trial were hyperglycemia and rash (which are considered on-target effects of PI3Kα inhibition) and gastrointestinal AEs, including diarrhea, nausea, and decreased appetite. These AEs require regular monitoring, early recognition, and prompt initiation of appropriate treatment. In addition, there are effective strategies to reduce the onset and severity of frequently observed AEs-in particular, onset of hyperglycemia and rash may be reduced by lifestyle changes (such as reduced intake of carbohydrates and regular exercise) and antihistamine prophylaxis, respectively. To reduce risk of severe hyperglycemia, it is essential to achieve adequate glycemic control prior to initiation of alpelisib treatment.ConclusionOverall, alpelisib-associated AEs are generally manageable with prompt recognition, regular monitoring, and appropriate intervention, preferably with a multidisciplinary approach.

Purpose: Phosphoinositide 3-kinase (PI3K) inhibition is used for the treatment of certain cancers, but can cause profound hyperglycemia and insulin resistance, for which sodium-glucose cotransporter-2 (SGLT2) inhibitors have been proposed as a preferred therapy. The objective of this research is to assess the effectiveness and safety of SGLT2 inhibitors for hyperglycemia in PI3K inhibition. Methods: We conducted a single-center retrospective review of adults initiating the PI3K inhibitor alpelisib. Exposure to different antidiabetic drugs and adverse events including diabetic ketoacidosis (DKA) were assessed through chart review. Plasma and point-of-care blood glucoses were extracted from the electronic medical record. Change in serum glucose and the rate of DKA on SGLT2 inhibitor versus other antidiabetic drugs were examined as co-primary outcomes. Results: We identified 103 patients meeting eligibility criteria with median follow-up of 92 days after starting alpelisib. When SGLT2 inhibitors were used to treat hyperglycemia, they were associated with a decrease in mean random glucose by -46 mg/dL (95% CI − 77 to − 15) in adjusted linear modeling. Five cases of DKA were identified, two occurring in patients on alpelisib plus SGLT2 inhibitor. Estimated incidence of DKA was: alpelisib plus SGLT2 inhibitor, 48 DKA cases per 100 patient-years (95% CI 6, 171); alpelisib with non-SGLT2 inhibitor antidiabetic drugs, 15 (95% CI 2, 53); alpelisib only, 4 (95% CI 0.1, 22). Conclusions: SGLT2 inhibitors are effective treatments for hyperglycemia in the setting of PI3K inhibition. [ABSTRACT FROM AUTHOR]

BackgroundThe BYLieve trial (NCT03056755) confirmed efficacy and safety of alpelisib with fulvestrant for hormone receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2-), PIK3CA-mutated advanced breast cancer (ABC), after cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) with an aromatase inhibitor (AI) as immediate prior therapy. Further analyses were performed to compare efficacy from BYLieve with effectiveness of standard treatment in the real-world setting.Materials and methodsPatients who progressed on a CDK4/6i plus AI and were treated with alpelisib with fulvestrant in BYLieve were matched with a real-world patient cohort who received standard-of-care from a deidentified clinico-genomics database (CGDB). Primary and secondary endpoints were to compare progression-free survival (PFS), estimated by the Kaplan-Meier method, and the proportion of patients remaining progression-free at 6 months, respectively, between the two cohorts.ResultsA total of 855 patients with PIK3CA-mutant disease who had prior CDK4/6i plus hormone therapy were selected from the CGDB; further matching to 120 patients from BYLieve selected 95 patients without exposure to HER2-targeting agents, clinical study drug, or alpelisib. In unadjusted and postmatching results, primary and secondary endpoints favored treatment with alpelisib with fulvestrant in BYLieve more than standard treatments in the real-world cohort. Postadjustment, median PFS for patients treated with alpelisib in BYLieve was 7.3 versus 3.7 months in the real-world cohort, and 6-month PFS was 54.6% versus 40.1%, respectively.ConclusionMatched/weighted analysis comparing BYLieve with the real-world setting further supports the clinical benefit of alpelisib with fulvestrant for treatment of HR+, HER2-, PIK3CA-mutant ABC after CDK4/6i treatment.Implications for practiceApproximately 40% of patients with hormone receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2-) advanced breast cancer (ABC) have PIK3CA-mutated tumors, which have been associated with endocrine therapy resistance. Alpelisib, an α-selective phosphatidylinositol-3-kinase inhibitor, demonstrated significantly improved progression-free survival in SOLAR-1 and demonstrated clinical efficacy in BYLieve when combined with fulvestrant. Data are limited in comparing the efficacy of alpelisib combined with fulvestrant with effectiveness of standard therapy after CDK4/6i treatment. Using real-world data, this is the first analysis comparing alpelisib combined with fulvestrant with standard treatments for HR+, HER2-, PIK3CA-mutant ABC in the post-CDK4/6i setting.

Abstract Background In neuroblastoma, hyperactivation of the PI3K signaling pathway has been correlated with aggressive neuroblastomas, suggesting PI3Ks as promising targets for the treatment of neuroblastoma. However, the oncogenic roles of individual PI3K isoforms in neuroblastoma remain elusive. Results We found that PI3K isoform p110α was expressed at higher levels in neuroblastoma tissues compared with normal tissues, and its high expression was correlated with an unfavorable prognosis of neuroblastoma. Accordingly, PI3K activation in neuroblastoma cells was predominantly mediated by p110α but not by p110β or p110δ. Suppression of p110α inhibited the growth of neuroblastoma cells both in vitro and in vivo, suggesting a crucial role of p110α in the tumorigenesis of neuroblastoma. Mechanistically, inhibition of p110α decreased anaplastic lymphoma kinase (ALK) in neuroblastoma cells by decreasing its protein stability. Conclusions In this study, we investigated the oncogenic roles of PI3K isoforms in neuroblastoma. Our data shed light on PI3K isoform p110α in the tumorigenesis of neuroblastoma, and strongly suggest the p110α inhibitors as potential drugs in treating neuroblastoma.

Canine mammary tumors (CMTs) are commonly observed in old and unspayed female dogs. Recently, dogs have been increasingly spaying at a young age to prevent mammary tumors. These CMTs require extensive local excision and exhibit a high probability of metastasis to the regional lymph nodes and lungs during malignancy. However, the molecular and biological mechanisms underlying CMT development have not been fully elucidated, and research in this area is limited. Therefore, in this study, we established new CMT cell lines by isolating cells from tumor tissues and investigated phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), a target for human breast cancer. PIK3CA mutations were observed at a similar loci as in the human PIK3CA gene in half of all canine samples. Furthermore, we investigated whether alpelisib, a PIK3CA inhibitor approved by the U.S. Food and Drug Administration for human breast cancer treatment, along with fulvestrant, is effective for CMT treatment. Alpelisib exerted stronger anticancer effects on cell lines with PIK3CA mutations than on the wild-type cell lines. In conclusion, we established new CMT cell lines with PIK3CA mutations and confirmed the efficacy of alpelisib for CMT treatment in vitro.

Alpelisib plus fulvestrant is a valid second or advanced line of treatment for patients with metastatic hormone receptor (HR)-positive, HER2-negative breast cancer who harbor an activating PIK3CA mutation. The well-known side effects of alpelisib are hyperglycemia, rash, and diarrhea. Herein, we report a case of a woman who developed diffuse depigmented macules on the face, arms and legs, three months after initiating alpelisib. Both clinical and histopathological findings were consistent with new-onset vitiligo. To our knowledge, this is the first case described in literature which suggests a causal relationship between alpelisib and irreversible dermatological adverse effect.

Background: HER2 is amplified or overexpressed in around 20% of breast cancers (BC). HER2-targeted therapies have significantly improved the prognosis of patients with HER2+ BC, however, de novo and acquired resistance to anti-HER2 treatment is common. Activating mutations in the PIK3CA gene are reported in ~30% of HER2+ BC and are associated with resistance to anti-HER2 therapies and a poor prognosis. Here, we investigated the in vitro and in vivo antitumor efficacy of the alpha-specific PI3K inhibitor alpelisib alone or in combination with anti-HER2 therapy using a panel of HER2+ BC cell lines. We also generated models of acquired resistance to alpelisib to investigate the mechanisms underlying resistance to alpha-specific PI3K inhibition. Materials and methods: PIK3CA mutant (HCC1954, KPL4 and JMT1) and wildtype (BT474 and SKBR3) HER2+ BC cell lines were used. The HCC1954 and KPL4 cells were chronically exposed to increasing concentrations of alpelisib or to alpelisib + trastuzumab in order to generate derivatives with acquired resistance to alpelisib (AR) and to alpelisib + trastuzumab (ATR). The transcriptomic profiles of HCC1954, KPL4 and their AR and ATR derivatives were determined by RNA sequencing. Cell growth was assessed by MTT assay. Changes in the protein levels of key PI3K pathway components were assessed by Western blotting. Gene expression, cellular and patients' data from the Cancer Dependency Map (DepMap) and KMPlot datasets were interrogated. Results: HER2+ BC cell lines harboring activating mutations in PIK3CA were less sensitive to single or dual anti-HER2 blockade compared to PIK3CA wild-type cells. Alpelisib treatment resulted in dose-dependent inhibition of the growth of cells with or without PIK3CA mutations and enhanced the antitumor efficacy of anti-HER2 therapies in vitro. In addition, alpelisib greatly delayed tumor growth of HCC1954 xenografts in vivo. Functional annotation of the significantly differentially expressed genes suggested the common activation of biological processes associated with oxidation reduction, cell proliferation, immune response and RNA synthesis in alpelisib-resistant models compared with native cells. Eight commonly upregulated genes (log2 fold-change >1, False Discovery Rate [FDR] <0.05) in models with acquired resistance to alpelisib or alpelisib + trastuzumab were identified. Among these, AKR1C1 was associated with alpelisib-resistance in vitro and with a poor prognosis in patients with HER2+ BC. Conclusions: Our findings support the use of an alpha-selective PI3K inhibitor to overcome the therapeutic limitations associated with single or dual HER2 blockade in PIK3CA-mutant HER2+ breast cancer. Future studies are warranted to confirm the potential role of candidate genes/pathways in resistance to alpelisib. [ABSTRACT FROM AUTHOR]

BackgroundHER2 is amplified or overexpressed in around 20% of breast cancers (BC). HER2-targeted therapies have significantly improved the prognosis of patients with HER2+ BC, however, de novo and acquired resistance to anti-HER2 treatment is common. Activating mutations in the PIK3CA gene are reported in ∼30% of HER2+ BC and are associated with resistance to anti-HER2 therapies and a poor prognosis. Here, we investigated the in vitro and in vivo antitumor efficacy of the alpha-specific PI3K inhibitor alpelisib alone or in combination with anti-HER2 therapy using a panel of HER2+ BC cell lines. We also generated models of acquired resistance to alpelisib to investigate the mechanisms underlying resistance to alpha-specific PI3K inhibition.Materials and methodsPIK3CA mutant (HCC1954, KPL4 and JMT1) and wild-type (BT474 and SKBR3) HER2+ BC cell lines were used. The HCC1954 and KPL4 cells were chronically exposed to increasing concentrations of alpelisib or to alpelisib + trastuzumab in order to generate derivatives with acquired resistance to alpelisib (AR) and to alpelisib + trastuzumab (ATR). The transcriptomic profiles of HCC1954, KPL4 and their AR and ATR derivatives were determined by RNA sequencing. Cell growth was assessed by MTT assay. Changes in the protein levels of key PI3K pathway components were assessed by Western blotting. Gene expression, cellular and patients’ data from the Cancer Dependency Map (DepMap) and KMPlot datasets were interrogated.ResultsHER2+ BC cell lines harboring activating mutations in PIK3CA were less sensitive to single or dual anti-HER2 blockade compared to PIK3CA wild-type cells. Alpelisib treatment resulted in dose-dependent inhibition of the growth of cells with or without PIK3CA mutations and enhanced the antitumor efficacy of anti-HER2 therapies in vitro. In addition, alpelisib greatly delayed tumor growth of HCC1954 xenografts in vivo. Functional annotation of the significantly differentially expressed genes suggested the common activation of biological processes associated with oxidation reduction, cell proliferation, immune response and RNA synthesis in alpelisib-resistant models compared with native cells. Eight commonly upregulated genes (log2 fold-change >1, False Discovery Rate [FDR]

Precision oncology based on specific molecular alterations requires precise and reliable detection of therapeutic targets in order to initiate the optimal treatment. In many European countries—including Germany—assays employed for this purpose are highly diverse and not prescribed by authorities, making inter-laboratory comparison difficult. To ensure reproducible molecular diagnostic results across many laboratories and different assays, ring trials are essential and a well-established tool. Here, we describe the design and results of the ring trial for the detection of therapeutically relevant PIK3CA hotspot mutations in HR+/HER2-breast cancer tissue and liquid biopsy (LB). For PIK3CA mutation detection in tissue samples, 43 of the 54 participants (80%) provided results compliant with the reference values. Participants using NGS-based assays showed higher success rate (82%) than those employing Sanger sequencing (57%). LB testing was performed with two reference materials differing in the length of the mutated DNA fragments. Most participants used NGS-based or commercial real-time PCR assays (70%). The 167 bp fragments led to a successful PIK3CA mutation detection by only 31% of participants whereas longer fragments of 490 bp were detectable even by non-optimal assays (83%). In conclusion, the first ring trial for PIK3CA mutation detection in Germany showed that PIK3CA mutation analysis is broadly established for tissue samples and that NGS-based tests seem to be more suitable than Sanger sequencing. PIK3CA mutation detection in LB should be carried out with assays specifically designed for this purpose in order to avoid false-negative results. [ABSTRACT FROM AUTHOR]

Activating mutations in the PIK3CA gene, causing phosphoinositide 3-kinase (PI3K) hyperactivation, are rare causes of hypoglycemia. We report the novel use of alpelisib (a PI3K inhibitor) for the treatment of hypoketotic, hypoinsulinemic hypoglycemia in 2 children with PIK3CA -related overgrowth spectrum (PROS). Patient 1 was a 7-month-old girl who presented with a hypoglycemic seizure. Despite nutritional management including continuous feeds, she continued to have frequent hypoglycemia. At age 2.8 years, alpelisib was started at 50 mg daily and titrated to 100 mg daily. She was weaned off nocturnal continuous feeds by 8 months. She developed colitis when the alpelisib dose was increased to 125 mg, but this resolved with a dose decrease and medical management. At age 5.3 years, she was doing well with rare hypoglycemia. Her accelerated growth stabilized. Patient 2 was a 3-year-old boy who developed hypoglycemia in early infancy. Alpelisib 50 mg daily was started due to recurrent hypoglycemia despite nutritional management. He came off continuous feeds after 4 months, with decreased hypoglycemia frequency. At age 4.5 years, he had not experienced side effects from treatment. In conclusion, alpelisib appears to be effective in decreasing PROS-related hypoglycemia frequency and severity and should be considered for refractory hypoglycemia in this condition. [ABSTRACT FROM AUTHOR]

Cervical carcinoma is a serious type of gynecological cancer that can affect women of all ages. Cervical carcinoma presents challenges for precision medicine, as not all tumors have specific gene mutations or alterations that can be targeted with existing drugs. Nonetheless, there are some promising targets in cervical carcinoma. Herein, genomic mutation data from The Cancer Genome Atlas and Catalogue of Somatic Mutations in Cancer were used to identify genomic targets for cervical carcinoma. PIK3CA was the most mutant gene among the promising targets, especially in cervical squamous cell carcinoma, and the mutated genes of cervical carcinoma were enriched in the RTK/PI3K/MAPK and Hippo pathways. In vitro, PIK3CA‐mutant cervical cancer cell lines showed higher sensitivity to Alpelisib than cancer cells without the PIK3CA mutation and the normal cells (HCerEpic). Protein–protein networks and co‐immunoprecipitation of PIK3CA revealed reduced interaction between p110α and ATR in PIK3CA‐mutant cervical cancer cells, which were sensitive to the combination of Alpelisib and cisplatin in vivo. Furthermore, Alpelisib significantly suppressed the proliferation and migration of PIK3CA‐mutant cervical cancer cells via inhibition of the AKT/mTOR pathway. Overall, Alpelisib showed antitumor effects and enhance cisplatin efficacy in PIK3CA‐mutant cervical cancer cells via PI3K/AKT pathways. Our study demonstrated the therapeutic potential of Alpelisib in PIK3CA‐mutant cervical carcinoma, which provides insights into precision medicine in cervical carcinoma. [ABSTRACT FROM AUTHOR]

Abstract Background Deregulation of cell-cycle pathway is ubiquitously observed in human papillomavirus negative (HPVneg) head and neck squamous cell carcinoma (HNSCC). Despite being an attractive target, CDK4/6 inhibition using palbociclib showed modest or conflicting results as monotherapy or in combination with platinum-based chemotherapy or cetuximab in HPVneg HNSCC. Thus, innovative agents to augment the efficacy of palbociclib in HPVneg HNSCC would be welcomed. Methods A collection of 162 FDA-approved and investigational agents was screened in combinatorial matrix format, and top combinations were validated in a broader panel of HPVneg HNSCC cell lines. Transcriptional profiling was conducted to explore the molecular mechanisms of drug synergy. Finally, the most potent palbociclib-based drug combination was evaluated and compared with palbociclib plus cetuximab or cisplatin in a panel of genetically diverse HPVneg HNSCC cell lines and patient-derived xenograft models. Results Palbociclib displayed limited efficacy in HPVneg HNSCC as monotherapy. The high-throughput combination drug screening provided a comprehensive palbociclib-based drug-drug interaction dataset, whereas significant synergistic effects were observed when palbociclib was combined with multiple agents, including inhibitors of the PI3K, EGFR, and MEK pathways. PI3K pathway inhibitors significantly reduced cell proliferation and induced cell-cycle arrest in HPVneg HNSCC cell lines when combined with palbociclib, and alpelisib (a PI3Kα inhibitor) was demonstrated to show the most potent synergy with particularly higher efficacy in HNSCCs bearing PIK3CA alterations. Notably, when compared with cisplatin and cetuximab, alpelisib exerted stronger synergism in a broader panel of cell lines. Mechanistically, RRM2-dependent epithelial mesenchymal transition (EMT) induced by palbociclib, was attenuated by alpelisib and cetuximab rather than cisplatin. Subsequently, PDX models with distinct genetic background further validated that palbociclib plus alpelisib had significant synergistic effects in models harboring PIK3CA amplification. Conclusions This study provides insights into the systematic combinatory effect associated with CDK4/6 inhibition and supports further initiation of clinical trials using the palbociclib plus alpelisib combination in HPVneg HNSCC with PIK3CA alterations.

Alpelisib plus fulvestrant is a valid second or advanced line of treatment for patients with metastatic hormone receptor (HR)-positive, HER2-negative breast cancer who harbor an activating PIK3CA mutation. The well-known side effects of alpelisib are hyperglycemia, rash, and diarrhea. Herein, we report a case of a woman who developed diffuse depigmented macules on the face, arms and legs, three months after initiating alpelisib. Both clinical and histopathological findings were consistent with new-onset vitiligo. To our knowledge, this is the first case described in literature which suggests a causal relationship between alpelisib and irreversible dermatological adverse effect. [ABSTRACT FROM AUTHOR]

Purpose: SOLAR-1 investigated alpelisib-fulvestrant (ALP + FLV) in patients with HR + /HER2-, PIK3CA-mutated advanced breast cancer and demonstrated a clinically significant increase in all-grade and grade (G) 3-4 hyperglycemia (HG) compared to placebo-fulvestrant. Given high rates of HG, a preventative protocol and identification of associated risk factors was implemented. Methods: This single-center, retrospective study included patients receiving ALP + FLV. One week before ALP initiation, patients started an insulin-sensitizer. Patients had fasting plasma glucose (FPG) levels drawn day 8, 15, 28, then monthly. Primary outcome was incidence of G2-4 HG by day 28. Risk factors assessed included age, BMI, FPG, and HbA1c. Number of risk factors were compared between patients with and without HG. Results: Sixteen women were included with median age of 59 years. The cohort was 69% White, 25% Black, 75% with BMI ≥ 25 kg/m2, and 50% with history of diabetes. By day 28, 9 patients (56%) had G2-4 HG, with only 3 (19%) G3 and zero G4. Patients with G2-4 HG had a median of 2 risk factors compared to only 1 if no HG (p = 0.03). 5 patients (31%) required a temporary hold of ALP and 3 (19%) required dose reduction due to HG. 13 patients permanently discontinued ALP—9 due to disease progression and 4 from an adverse event (only 1 HG). Conclusion: Implementation of a HG prophylaxis protocol with ALP in a single-center study demonstrated fewer G3-4 HG events compared to that seen in SOLAR-1 (19% vs 36.6%). An increase in HG-associated risk factors correlated with a higher incidence of G2-4 HG. [ABSTRACT FROM AUTHOR]

Background: In neuroblastoma, hyperactivation of the PI3K signaling pathway has been correlated with aggressive neuroblastomas, suggesting PI3Ks as promising targets for the treatment of neuroblastoma. However, the oncogenic roles of individual PI3K isoforms in neuroblastoma remain elusive. Results: We found that PI3K isoform p110α was expressed at higher levels in neuroblastoma tissues compared with normal tissues, and its high expression was correlated with an unfavorable prognosis of neuroblastoma. Accordingly, PI3K activation in neuroblastoma cells was predominantly mediated by p110α but not by p110β or p110δ. Suppression of p110α inhibited the growth of neuroblastoma cells both in vitro and in vivo, suggesting a crucial role of p110α in the tumorigenesis of neuroblastoma. Mechanistically, inhibition of p110α decreased anaplastic lymphoma kinase (ALK) in neuroblastoma cells by decreasing its protein stability. Conclusions: In this study, we investigated the oncogenic roles of PI3K isoforms in neuroblastoma. Our data shed light on PI3K isoform p110α in the tumorigenesis of neuroblastoma, and strongly suggest the p110α inhibitors as potential drugs in treating neuroblastoma. [ABSTRACT FROM AUTHOR]

Purpose: The oral, α-specific phosphatidylinositol-3-kinase (PI3Kα) inhibitor alpelisib is the first PI3K inhibitor approved for the treatment of advanced breast cancer. As alpelisib is a relatively new therapeutic option, specific guidance and a multidisciplinary approach are needed to provide optimal patient care. The primary objective of this manuscript is to provide comprehensive guidance on minimizing and managing adverse events (AEs) for patients with advanced breast cancer who are receiving alpelisib. Methods: Clinical studies, prescribing information, published literature, and relevant guidelines were reviewed to provide recommendations on the prevention and management of alpelisib-associated AEs. Results: The most common AEs associated with alpelisib in the phase 3 SOLAR-1 trial were hyperglycemia and rash (which are considered on-target effects of PI3Kα inhibition) and gastrointestinal AEs, including diarrhea, nausea, and decreased appetite. These AEs require regular monitoring, early recognition, and prompt initiation of appropriate treatment. In addition, there are effective strategies to reduce the onset and severity of frequently observed AEs—in particular, onset of hyperglycemia and rash may be reduced by lifestyle changes (such as reduced intake of carbohydrates and regular exercise) and antihistamine prophylaxis, respectively. To reduce risk of severe hyperglycemia, it is essential to achieve adequate glycemic control prior to initiation of alpelisib treatment. Conclusion: Overall, alpelisib-associated AEs are generally manageable with prompt recognition, regular monitoring, and appropriate intervention, preferably with a multidisciplinary approach.

Background: It is critically important to study the real-world data of FDAapproved medications to understand the response rates and toxicities observed in the real-world population not represented in the clinical trials. Methods: We reviewed charts of patients diagnosed with metastatic, hormone receptor-positive, human epidermal growth factor receptor 2 negative, PIK3CA-mutated breast cancer treated with alpelisib from May 2019 to January 2022. Clinical characteristics and treatment outcomes were collected. The association of clinical characteristics with responses and adverse events (AEs) was evaluated using the logistic regression model. Results: 27 patients were included. Median age at alpelisib initiation 67 years (range: 44, 77 years). Majority of patients had excellent performance status at time of alpelisib initiation. Most patients had chronic comorbidities, notably; 2 patients had controlled type 2 diabetes mellitus at time of alpelisib initiation. Majority had a median of three lines of therapy (range: 1, 7) before alpelisib. Clinical responses were determined using RECIST v1.1. 3/27 (11.11%) patients discontinued therapy before response assessment due to grade 3 AEs. Overall response rate was 12.5% (3/24), with all partial responses (PR). The median duration of response was 5.77 months (range: 5.54, 8.98). 14/27 (51.9%) of patients required dose interruption/reduction. Overall, 23/27 (85.19%) patients discontinued alpelisib of which 11 (47.83%) discontinued alpelisib due to AEs. Median duration of treatment was 2 months in patients who had grade 3 AEs (range: <1.00, 8.30) and 6.28 (1.15, 10.43) in those who did not. Any grade AEs were reported in 24/27 (88.9%) patients, namely, hyperglycemia 16/27 (59.3%), nausea 11/27 (40.7%), diarrhea 10/27 (37.0%), fatigue 7/27 (25.9%) and rash 6/27 (22.2%). Grade 3 AEs were reported in 13/27 patients (50%), namely, hyperglycemia in 7/27 (53.8%) patients followed by skin rash 4/27 (30.8%), GI side effects 3/27 (23.1%). Those with progressive disease as best response to alpelisib, had more non-metabolic comorbidities, higher number of liver metastases, PIK3CA E545K mutations, and shorter duration on therapy compared to those with PR and stable disease. Conclusion: Patients should be counseled about the toxicity and modest benefit observed with alpelisib in real-world clinical practice when used in later lines of therapy. [ABSTRACT FROM AUTHOR]

BackgroundIt is critically important to study the real-world data of FDA-approved medications to understand the response rates and toxicities observed in the real-world population not represented in the clinical trials.MethodsWe reviewed charts of patients diagnosed with metastatic, hormone receptor-positive, human epidermal growth factor receptor 2 negative, PIK3CA-mutated breast cancer treated with alpelisib from May 2019 to January 2022. Clinical characteristics and treatment outcomes were collected. The association of clinical characteristics with responses and adverse events (AEs) was evaluated using the logistic regression model.Results27 patients were included. Median age at alpelisib initiation 67 years (range: 44, 77 years). Majority of patients had excellent performance status at time of alpelisib initiation. Most patients had chronic comorbidities, notably; 2 patients had controlled type 2 diabetes mellitus at time of alpelisib initiation. Majority had a median of three lines of therapy (range: 1, 7) before alpelisib. Clinical responses were determined using RECIST v1.1. 3/27 (11.11%) patients discontinued therapy before response assessment due to grade 3 AEs. Overall response rate was 12.5% (3/24), with all partial responses (PR). The median duration of response was 5.77 months (range: 5.54, 8.98). 14/27 (51.9%) of patients required dose interruption/reduction. Overall, 23/27 (85.19%) patients discontinued alpelisib of which 11 (47.83%) discontinued alpelisib due to AEs. Median duration of treatment was 2 months in patients who had grade 3 AEs (range:

Abstract Background PIK3CA-related disorders include vascular malformations and overgrowth of various tissues that are caused by postzygotic, somatic variants in the gene encoding phosphatidylinositol-3-kinase (PI3K) catalytic subunit alpha. These mutations result in activation of the PI3K/AKT/mTOR signaling pathway. The goals of this review are to provide education on the underlying mechanism of disease for this group of rare conditions and to summarize recent advancements in the understanding of, as well as current and emerging treatment options for PIK3CA-related disorders. Main body PIK3CA-related disorders include PIK3CA-related overgrowth spectrum (PROS), PIK3CA-related vascular malformations, and PIK3CA-related nonvascular lesions. Somatic activating mutations (predominantly in hotspots in the helical and kinase domains of PIK3CA, but also in other domains), lead to hyperactivation of the PI3K signaling pathway, which results in abnormal tissue growth. Diagnosis is complicated by the variability and overlap in phenotypes associated with PIK3CA-related disorders and should be performed by clinicians with the required expertise along with coordinated care from a multidisciplinary team. Although tissue mosaicism presents challenges for confirmation of PIK3CA mutations, next-generation sequencing and tissue selection have improved detection. Clinical improvement, radiological response, and patient-reported outcomes are typically used to assess treatment response in clinical studies of patients with PIK3CA-related disorders, but objective assessment of treatment response is difficult using imaging (due to the heterogeneous nature of these disorders, superimposed upon patient growth and development). Despite their limitations, patient-reported outcome tools may be best suited to gauge patient improvement. New therapeutic options are needed to provide an alternative or supplement to standard approaches such as surgery and sclerotherapy. Currently, there are no systemic agents that have regulatory approval for these disorders, but the mTOR inhibitor sirolimus has been used for several years in clinical trials and off label to address symptoms. There are also other agents under investigation for PIK3CA-related disorders that act as inhibitors to target different components of the PI3K signaling pathway including AKT (miransertib) and PI3K alpha (alpelisib). Conclusion Management of patients with PIK3CA-related disorders requires a multidisciplinary approach. Further results from ongoing clinical studies of agents targeting the PI3K pathway are highly anticipated.

Background: Deregulation of cell-cycle pathway is ubiquitously observed in human papillomavirus negative (HPVneg) head and neck squamous cell carcinoma (HNSCC). Despite being an attractive target, CDK4/6 inhibition using palbociclib showed modest or conflicting results as monotherapy or in combination with platinum-based chemotherapy or cetuximab in HPVneg HNSCC. Thus, innovative agents to augment the efficacy of palbociclib in HPVneg HNSCC would be welcomed. Methods: A collection of 162 FDA-approved and investigational agents was screened in combinatorial matrix format, and top combinations were validated in a broader panel of HPVneg HNSCC cell lines. Transcriptional profiling was conducted to explore the molecular mechanisms of drug synergy. Finally, the most potent palbociclib-based drug combination was evaluated and compared with palbociclib plus cetuximab or cisplatin in a panel of genetically diverse HPVneg HNSCC cell lines and patient-derived xenograft models. Results: Palbociclib displayed limited efficacy in HPVneg HNSCC as monotherapy. The high-throughput combination drug screening provided a comprehensive palbociclib-based drug-drug interaction dataset, whereas significant synergistic effects were observed when palbociclib was combined with multiple agents, including inhibitors of the PI3K, EGFR, and MEK pathways. PI3K pathway inhibitors significantly reduced cell proliferation and induced cell-cycle arrest in HPVneg HNSCC cell lines when combined with palbociclib, and alpelisib (a PI3Kα inhibitor) was demonstrated to show the most potent synergy with particularly higher efficacy in HNSCCs bearing PIK3CA alterations. Notably, when compared with cisplatin and cetuximab, alpelisib exerted stronger synergism in a broader panel of cell lines. Mechanistically, RRM2-dependent epithelial mesenchymal transition (EMT) induced by palbociclib, was attenuated by alpelisib and cetuximab rather than cisplatin. Subsequently, PDX models with distinct genetic background further validated that palbociclib plus alpelisib had significant synergistic effects in models harboring PIK3CA amplification. Conclusions: This study provides insights into the systematic combinatory effect associated with CDK4/6 inhibition and supports further initiation of clinical trials using the palbociclib plus alpelisib combination in HPVneg HNSCC with PIK3CA alterations. [ABSTRACT FROM AUTHOR]

Pulmonary vein stenosis is a rare and frequently lethal childhood disease. There are few known genetic associations, and the pathophysiology is not well known. Current treatments include surgery, interventional cardiac catheterization, and more recently, medications targeting cell proliferation, which are not uniformly effective. We present a patient with PVS and a PIK3CA mutation, who demonstrated a good response to the targeted inhibitor, alpelisib. [ABSTRACT FROM AUTHOR]

Introduction. Breast cancer is the leader in cancer incidence in theRussian Federation. The tumor is considered extremely heterogeneous and the luminal subtypes of breast tumors occupy a special place, since they are considered relatively favorable in therapy and control of the disease.Drug therapy for hormone-positive cancer has undergone significant evolution and new anticancer agents have appeared in the arsenal of the oncologist and have shown promising results compared to classical therapy. The search for predictive markers of the effectiveness of new therapy has become of great importance. This marker turned out to be a mutation in the PIK3CA gene – one of the most frequent genetic disorders in breast cancer cells. According to the literature, the presence of this mutation negatively effects on endocrine therapy for breast tumors.The aim of this study was to analyze the frequency of mutations in the PIK3CA gene among patients with hormone-positive tumors, and the effectiveness of therapy with CDK4/6 inhibitors in this group of patients.Materials and methods. The material for the study of the mutation in the PIK3CA gene was tumor biopsies of 31 patients and clinical data on the response to therapy with CDK4/6 inhibitors and classical hormone therapy.Results and discussion. The results of the work showed a high incidence of the PIK3CA mutation among hormone-positive tumors (45%). The mutation resulted in a decrease in both the median time to progression after radical surgery (from 48.4 ± 7.8 months to 30.1 ± 6.0 months) in patients receiving adjuvant hormone therapy and progression-free survival in patients receiving therapy with CDK4 /6 inhibitors (4.2 months versus 9 months). This confirmed the theory that the PIK3CA mutation negatively affects the outcome of hormone therapy.Conclusions. PIK3CA is an important predictive marker in endocrine therapy for hormone-positive tumors. Its presence not only determines the relatively worse results of treatment, but can also serve as an indication for the appointment of a special series of drugs – inhibitors of this mutation.

Avan J Armaghani, Hyo Sook Han Department of Breast Oncology, Moffitt McKinley Outpatient Center, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USACorrespondence: Avan J Armaghani Email avan.armaghani@moffitt.orgAbstract: Hormone receptor positive, human epidermal growth factor receptor 2 negative (HR+/HER2 negative) breast cancer accounts for over 70% of all breast cancers. There has been much advancement in the treatment of HR+/HER2 negative metastatic breast cancer (MBC), in particular the development of more tailored and targeted therapies. Recently, greater understanding of the role of phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway in breast cancer has led to the development of PI3K inhibitors, which have proven to be effective in the treatment of HR+/HER2 negative MBC. In this review, we will discuss the role of the PI3K/AKT/mTOR pathway in breast cancer and therapies that have been developed to inhibit PI3K. We will discuss in detail the development of PI3K inhibitor alpelisib, indications for use in HR+/HER2 negative MBC, safety and tolerability and the future direction of this therapy in the treatment of breast cancer.Keywords: PI3K, PIK3CA, alpelisib

Abstract Breast cancer is the most common cancer in women, and approximately 71% of carcinomas are hormone receptor‐positive (HR+) and human epidermal growth factor receptor 2‐not‐amplified (HER2‐negative). Pathogenesis of breast cancer is associated with dysregulation of several signaling pathways, including the phosphatidylinositol‐3‐kinase (PI3K) pathway. PIK3CA, the gene encoding PI3K catalytic subunit p110α, is mutated in 20%‐40% of breast cancer patients. Several PI3K inhibitors have been developed and one, alpelisib, was recently approved for use in PIK3CA‐mutated, HR+, HER2‐negative advanced breast cancer. There are numerous types of assays and methods used in clinical studies to determine PIK3CA status in cancers. Additionally, there are several factors to consider for PIK3CA testing in clinical practice, including choice of assay, source of sample, and test timing. In this review, we discuss the use of PIK3CA as a biomarker to guide treatment decisions in patients with HR+, HER2‐negative advanced breast cancer, as well as practical considerations and recommendations for testing.

Abstract Purpose The therascreen PIK3CA mutation assay and the alpha-specific PI3K inhibitor alpelisib are FDA-approved for identifying and treating patients with advanced PIK3CA-mutated (PIK3CAmut) breast cancer (BC). However, it is currently unknown to what extend this assay detects most PIK3CA mutations in BC. This information is critical as patients and clinicians are using this and other genomic assays to indicate alpelisib. Methods Data from 6338 patients with BC was explored across 10 publicly available studies. The primary objective was to evaluate the proportion and distribution of PIK3CA mutations in BC. Secondary objectives were (1) to evaluate in silico the spectrum of PIK3CA mutations in BC that would be captured by the therascreen panel; (2) to evaluate the proportion and distribution of PIK3CA mutations in hormone receptor-positive/HER2-negative (HR+/HER2−), HER2+, and triple-negative BC (TNBC); and (3) to explore the identification of PIK3CA mutations in a cohort of 48 HR+/HER2− advanced BC patients by the Guardant B360 circulating tumor DNA (ctDNA) assay. Results Patients with PIK3CAmut tumors represented 35.7% (2261/6338). Five PIK3CA mutations comprised 73% of all PIK3CA mutations: H1047R (35%), E545K (17%), E542K (11%), N345K (6%), and H1047L (4%). Therascreen gene list would capture 72% of all PIK3CA mutations and 80% of patients with a known PIK3CAmut BC. Among patients with double PIK3CAmut tumors (12% of all PIK3CAmut), the therascreen panel would capture 78% as harboring 1 single PIK3CA mutation, 17% as PIK3CAmut undetected, and 5% as PIK3CA double-mut. PIK3CA mutation rates were lower in TNBC (16%) compared to HR+/HER2 (42%) and HER2+ (31%) BC; however, the distribution of the 4 main PIK3CA mutations across subtypes was similar. Finally, 28% of PIK3CA mutations identified in ctDNA in 48 patients with advanced HR+/HER2− BC were not part of the therascreen panel. Conclusion PIK3CA mutations in BC are heterogenous and ~ 20% of patients with a known PIK3CA mutation, and 95% with a known double PIK3CAmut tumor, would not be captured by the therascreen panel. Finally, the clinical utility of PIK3CA mutations not present in the therascreen companion diagnostic assay or identified by other sequencing-based assays needs further investigation.

The oral, α-specific phosphatidylinositol-3-kinase (PI3Kα) inhibitor alpelisib is the first PI3K inhibitor approved for the treatment of advanced breast cancer. As alpelisib is a relatively new therapeutic option, specific guidance and a multidisciplinary approach are needed to provide optimal patient care. The primary objective of this manuscript is to provide comprehensive guidance on minimizing and managing adverse events (AEs) for patients with advanced breast cancer who are receiving alpelisib. Clinical studies, prescribing information, published literature, and relevant guidelines were reviewed to provide recommendations on the prevention and management of alpelisib-associated AEs. The most common AEs associated with alpelisib in the phase 3 SOLAR-1 trial were hyperglycemia and rash (which are considered on-target effects of PI3Kα inhibition) and gastrointestinal AEs, including diarrhea, nausea, and decreased appetite. These AEs require regular monitoring, early recognition, and prompt initiation of appropriate treatment. In addition, there are effective strategies to reduce the onset and severity of frequently observed AEs—in particular, onset of hyperglycemia and rash may be reduced by lifestyle changes (such as reduced intake of carbohydrates and regular exercise) and antihistamine prophylaxis, respectively. To reduce risk of severe hyperglycemia, it is essential to achieve adequate glycemic control prior to initiation of alpelisib treatment. Overall, alpelisib-associated AEs are generally manageable with prompt recognition, regular monitoring, and appropriate intervention, preferably with a multidisciplinary approach. • Alpelisib-associated AEs are generally manageable and reversible • PI3K inhibitor-associated hyperglycemia is an on-target and transient event • Use of prophylactic antihistamines may reduce onset and severity of rash • Enhanced monitoring and management guidance results in fewer drug discontinuations • Further studies are ongoing to optimize management of alpelisib-associated AEs [ABSTRACT FROM AUTHOR]

Phosphatidylinositol-3-kinase (PI3K) pathway hyperactivation has been associated with the development of cancer and treatment resistance. PI3K inhibitors are now used to treat hormone receptor-positive (HR+), human epidermal growth factor receptor-2–negative (HER2−), PIK3CA- mutated advanced breast cancer. Hyperglycemia, a frequently observed adverse event with PI3K inhibitors (PI3Ki), is regarded as an on-target effect because inhibition of the PI3K pathway has been shown to decrease glucose transport and increase glycogenolysis and gluconeogenesis. PI3Ki-induced hyperglycemia results in a compensatory increase in insulin release, which has been shown to reduce the efficacy of treatment by reactivating the PI3K pathway in preclinical models. Patients with an absolute or relative deficiency in insulin, and those with insulin resistance or pancreatic dysfunction, may experience exacerbated or prolonged hyperglycemia. Therefore, the effective management of PI3Ki-associated hyperglycemia depends on early identification of patients at risk, frequent monitoring to allow prompt recognition of hyperglycemia and its sequelae, and initiating appropriate management strategies. Risk factors for the development of hyperglycemia include older age (≥75 years), overweight/obese at baseline, and family history of diabetes. Consultation with an endocrinologist is recommended for patients considered high risk. The management of PI3Ki-induced hyperglycemia requires an integrative approach that combines diets low in carbohydrates and glucose-lowering medications. Medications that do not affect the PI3K pathway are preferred as the primary and secondary agents for the management of hyperglycemia. These include metformin, sodium-glucose co-transporter 2 inhibitors, thiazolidinediones, and α-glucosidase inhibitors. Insulin should only be considered as a last-line agent for PI3Ki-associated hyperglycemia due to its stimulatory effect of PI3K signaling. Clinical studies show that alpelisib-associated hyperglycemia is reversible and manageable, rarely leading to treatment discontinuation. Management of PI3Ki-associated hyperglycemia in patients with breast cancer should focus on the prevention of acute and subacute complications of hyperglycemia, allowing patients to remain on anticancer treatment longer. [ABSTRACT FROM AUTHOR]

Background: PIK3CA-related disorders include vascular malformations and overgrowth of various tissues that are caused by postzygotic, somatic variants in the gene encoding phosphatidylinositol-3-kinase (PI3K) catalytic subunit alpha. These mutations result in activation of the PI3K/AKT/mTOR signaling pathway. The goals of this review are to provide education on the underlying mechanism of disease for this group of rare conditions and to summarize recent advancements in the understanding of, as well as current and emerging treatment options for PIK3CA-related disorders.Main Body: PIK3CA-related disorders include PIK3CA-related overgrowth spectrum (PROS), PIK3CA-related vascular malformations, and PIK3CA-related nonvascular lesions. Somatic activating mutations (predominantly in hotspots in the helical and kinase domains of PIK3CA, but also in other domains), lead to hyperactivation of the PI3K signaling pathway, which results in abnormal tissue growth. Diagnosis is complicated by the variability and overlap in phenotypes associated with PIK3CA-related disorders and should be performed by clinicians with the required expertise along with coordinated care from a multidisciplinary team. Although tissue mosaicism presents challenges for confirmation of PIK3CA mutations, next-generation sequencing and tissue selection have improved detection. Clinical improvement, radiological response, and patient-reported outcomes are typically used to assess treatment response in clinical studies of patients with PIK3CA-related disorders, but objective assessment of treatment response is difficult using imaging (due to the heterogeneous nature of these disorders, superimposed upon patient growth and development). Despite their limitations, patient-reported outcome tools may be best suited to gauge patient improvement. New therapeutic options are needed to provide an alternative or supplement to standard approaches such as surgery and sclerotherapy. Currently, there are no systemic agents that have regulatory approval for these disorders, but the mTOR inhibitor sirolimus has been used for several years in clinical trials and off label to address symptoms. There are also other agents under investigation for PIK3CA-related disorders that act as inhibitors to target different components of the PI3K signaling pathway including AKT (miransertib) and PI3K alpha (alpelisib).Conclusion: Management of patients with PIK3CA-related disorders requires a multidisciplinary approach. Further results from ongoing clinical studies of agents targeting the PI3K pathway are highly anticipated. [ABSTRACT FROM AUTHOR]

Introduction: The phosphatidylinositol-3-kinase (PI3K) inhibitor alpelisib is the only approved agent for treating -PIK3CA-mutated, hormone receptor-positive (HR+) human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (ABC). Trials have reported hyperglycemia, diarrhea, and rash as the main grade 3 side effects. Methods: In a managed access program (ClinicalTrials.gov ID: NCT03706573; start: 06/2019), 8 HR+ HER2– ABC patients with a median 4.5 prior therapy lines were treated with alpelisib at the Breast Center of the Ludwig-Maximilian University (LMU) Hospital, Munich, based on the results of a new-generation sequencing (NGS) panel and PIK3CA mutation analysis by the Molecular Tumor Board of the Comprehensive Cancer Center, Munich. Results: Median therapy duration was 3.42 months for patients who discontinued and 3.95 months for those still on alpelisib (4 pts). Five had hyperglycemia (1 with grade 3) with fasting glucose levels of up to 450 mg/dL that required hospitalization and insulin therapy. Two experienced rash (grades 1 and 3) and 2 reported grade 3 diarrhea. Supportive therapy as well as interruption and/or dose reduction were necessary to control treatment-associated side effects. Conclusion: Patient education and a well-trained, interdisciplinary team including diabetologists, from the initiation of alpelisib treatment onwards, are essential to safely treat ABC patients with this new drug and to maintain their quality of life and ensure their survival. [ABSTRACT FROM AUTHOR]

Pulmonary vein stenosis is a rare and frequently lethal childhood disease. There are few known genetic associations, and the pathophysiology is not well known. Current treatments include surgery, interventional cardiac catheterization, and more recently, medications targeting cell proliferation, which are not uniformly effective. We present a patient with PVS and a PIK3CA mutation, who demonstrated a good response to the targeted inhibitor, alpelisib.

Mutations that activate growth factor signaling often drive cancer growth. Many also arise in isolation, causing developmental growth disorders. PIK3CA , that encodes a catalytic subunit of phosphatidylinositol 3-kinase (PI3K), is a cardinal example of this paradigm. Recent exciting progress towards the key goal of cancer drug repurposing for PIK3CA-driven overgrowth is discussed. [ABSTRACT FROM AUTHOR]

Activation of the phosphatidylinositol-3-kinase (PI3K) pathway via PIK3CA mutations occurs in 28%-46% of hormone receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2−) advanced breast cancers (ABCs) and is associated with poor prognosis. The SOLAR-1 trial showed that the addition of alpelisib to fulvestrant treatment provided statistically significant and clinically meaningful progression-free survival (PFS) benefit in PIK3CA -mutated, HR+, HER2− ABC. Men and postmenopausal women with HR+, HER2− ABC whose disease progressed on or after aromatase inhibitor (AI) were randomized 1 : 1 to receive alpelisib (300 mg/day) plus fulvestrant (500 mg every 28 days and once on day 15) or placebo plus fulvestrant. Overall survival (OS) in the PIK3CA -mutant cohort was evaluated by Kaplan–Meier methodology and a one-sided stratified log-rank test was carried out with an O'Brien–Fleming efficacy boundary of P ≤ 0.0161. In the PIK3CA -mutated cohort (n = 341), median OS [95% confidence interval (CI)] was 39.3 months (34.1-44.9) for alpelisib-fulvestrant and 31.4 months (26.8-41.3) for placebo-fulvestrant [hazard ratio (HR) = 0.86 (95% CI, 0.64-1.15; P = 0.15)]. OS results did not cross the prespecified efficacy boundary. Median OS (95% CI) in patients with lung and/or liver metastases was 37.2 months (28.7-43.6) and 22.8 months (19.0-26.8) in the alpelisib-fulvestrant and placebo-fulvestrant arms, respectively [HR = 0.68 (0.46-1.00)]. Median times to chemotherapy (95% CI) for the alpelisib-fulvestrant and placebo-fulvestrant arms were 23.3 months (15.2-28.4) and 14.8 months (10.5-22.6), respectively [HR = 0.72 (0.54-0.95)]. No new safety signals were observed with longer follow-up. Although the analysis did not cross the prespecified boundary for statistical significance, there was a 7.9-month numeric improvement in median OS when alpelisib was added to fulvestrant treatment of patients with PIK3CA -mutated, HR+, HER2− ABC. Overall, these results further support the statistically significant prolongation of PFS observed with alpelisib plus fulvestrant in this population, which has a poor prognosis due to a PIK3CA mutation. NCT02437318. • In SOLAR-1, the key secondary endpoint of OS was evaluated in patients with HR+, HER2−, PIK3CA -mutated ABC. • Adding alpelisib to fulvestrant numerically improved mOS by 7.9 months, though the result was not statistically significant. • OS was numerically improved in hard-to-treat disease, including a 14-month median improvement in those with lung/liver metastases. • Median time to first chemotherapy was delayed by 8.5 months with the addition of alpelisib to fulvestrant. • With longer follow-up the alpelisib plus fulvestrant safety profile was similar to prior reports with no new safety signals. [ABSTRACT FROM AUTHOR]

Breast cancer is the most common cancer in women, and approximately 71% of carcinomas are hormone receptor‐positive (HR+) and human epidermal growth factor receptor 2‐not‐amplified (HER2‐negative). Pathogenesis of breast cancer is associated with dysregulation of several signaling pathways, including the phosphatidylinositol‐3‐kinase (PI3K) pathway. PIK3CA, the gene encoding PI3K catalytic subunit p110α, is mutated in 20%‐40% of breast cancer patients. Several PI3K inhibitors have been developed and one, alpelisib, was recently approved for use in PIK3CA‐mutated, HR+, HER2‐negative advanced breast cancer. There are numerous types of assays and methods used in clinical studies to determine PIK3CA status in cancers. Additionally, there are several factors to consider for PIK3CA testing in clinical practice, including choice of assay, source of sample, and test timing. In this review, we discuss the use of PIK3CA as a biomarker to guide treatment decisions in patients with HR+, HER2‐negative advanced breast cancer, as well as practical considerations and recommendations for testing. [ABSTRACT FROM AUTHOR]

Purpose: Rash develops in approximately 50% of patients receiving alpelisib for breast cancer, often requiring dose modifications. Here, we describe the clinicopathologic, laboratory, and management characteristics of alpelisib-related dermatologic adverse events (dAEs). Methods: A single center-retrospective analysis was conducted. Data were abstracted from electronic medical records. Results: A total of 102 patients (mean age 56 years, range 27–83) receiving alpelisib most frequently in combination with endocrine therapy (79, 77.5%) were included. We identified 41 (40.2%) patients with all-grade rash distributed primarily along the trunk (78%) and extremities (70%) that developed approximately within two weeks of treatment initiation (mean 12.8 ± 1.5 days) and lasted one-week (mean duration 7.1 ± 0.8 days). Of 29 patients with documented morphology of alpelisib-related dAEs, 26 (89.7%) had maculopapular rash. Histology showed perivascular and interface lymphocytic dermatitis. All-grade rash correlated with an increase in serum eosinophils from 2.7 to 4.4%, p < 0.05, and prophylaxis with non-sedating antihistamines (n = 43) was correlated with a reduction of grade 1/2 rash (OR 0.39, p = 0.09). Sixteen (84.2%) of 19 patients with grade 3 dAEs resulted in interruption of alpelisib, which were managed with antihistamines, topical and systemic corticosteroids. We did not observe rash recurrence in 12 (75%) patients who were re-challenged. Conclusions: A maculopapular rash associated with increased blood eosinophils occurs frequently with alpelisib. While grade 3 rash leads to alpelisib therapy interruption, dermatologic improvement is evident with systemic corticosteroids; and most patients can continue oncologic treatment at a maintained or reduced dose upon re-challenge with alpelisib. [ABSTRACT FROM AUTHOR]

Purpose of Review: Cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors have revolutionized the treatment landscape for patients with hormone receptor-positive (HR+) and HER2-negative (HER2−) metastatic breast cancer (MBC). However, optimal therapy after CDK4/6 inhibitors is unknown. This review provides an update on recent understanding of potential resistance mechanisms to CDK4/6 inhibitors and therapeutic strategies. Recent Findings: CDK4/6 inhibitors are broadly effective for HR+/HER2− MBC. However, intrinsic and acquired resistance is inevitable. Although there are no established clinical predictors of response aside from ER positivity, several cell cycle-specific and non-specific mechanisms have emerged as potential resistance biomarkers and therapeutic targets in recent studies. Examples include loss of function mutations in RB1 or FAT1, overexpression or amplification of CDK6 and CCNE1, alterations of FGFR, and PI3K/mTOR-mediated CDK2 activation. Summary: Biomarker studies and clinical trials targeting CDK4/6 inhibitor resistance are critical to improve treatments for HR+/HER2− MBC. [ABSTRACT FROM AUTHOR]

Purpose: The therascreen PIK3CA mutation assay and the alpha-specific PI3K inhibitor alpelisib are FDA-approved for identifying and treating patients with advanced PIK3CA-mutated (PIK3CAmut) breast cancer (BC). However, it is currently unknown to what extend this assay detects most PIK3CA mutations in BC. This information is critical as patients and clinicians are using this and other genomic assays to indicate alpelisib.Methods: Data from 6338 patients with BC was explored across 10 publicly available studies. The primary objective was to evaluate the proportion and distribution of PIK3CA mutations in BC. Secondary objectives were (1) to evaluate in silico the spectrum of PIK3CA mutations in BC that would be captured by the therascreen panel; (2) to evaluate the proportion and distribution of PIK3CA mutations in hormone receptor-positive/HER2-negative (HR+/HER2-), HER2+, and triple-negative BC (TNBC); and (3) to explore the identification of PIK3CA mutations in a cohort of 48 HR+/HER2- advanced BC patients by the Guardant B360 circulating tumor DNA (ctDNA) assay.Results: Patients with PIK3CAmut tumors represented 35.7% (2261/6338). Five PIK3CA mutations comprised 73% of all PIK3CA mutations: H1047R (35%), E545K (17%), E542K (11%), N345K (6%), and H1047L (4%). Therascreen gene list would capture 72% of all PIK3CA mutations and 80% of patients with a known PIK3CAmut BC. Among patients with double PIK3CAmut tumors (12% of all PIK3CAmut), the therascreen panel would capture 78% as harboring 1 single PIK3CA mutation, 17% as PIK3CAmut undetected, and 5% as PIK3CA double-mut. PIK3CA mutation rates were lower in TNBC (16%) compared to HR+/HER2 (42%) and HER2+ (31%) BC; however, the distribution of the 4 main PIK3CA mutations across subtypes was similar. Finally, 28% of PIK3CA mutations identified in ctDNA in 48 patients with advanced HR+/HER2- BC were not part of the therascreen panel.Conclusion: PIK3CA mutations in BC are heterogenous and ~ 20% of patients with a known PIK3CA mutation, and 95% with a known double PIK3CAmut tumor, would not be captured by the therascreen panel. Finally, the clinical utility of PIK3CA mutations not present in the therascreen companion diagnostic assay or identified by other sequencing-based assays needs further investigation. [ABSTRACT FROM AUTHOR]

This phase I study aimed to determine tolerability and preliminary efficacy of single‐agent alpelisib (BYL719) in Japanese patients with advanced solid malignancies. The primary objective of the study was to estimate the maximum tolerated dose (MTD) and/or recommended phase II dose (RP2D) of oral alpelisib in patients with advanced solid tumors who had progressed despite standard therapy. The expansion part included patients with PIK3CA mutation/amplification; safety, preliminary efficacy, pharmacokinetic (PK)/pharmacodynamic profile, and food effect on the PK profile of alpelisib at the MTD/RP2D were determined. Oral alpelisib was given as a single agent on a continuous 28‐day treatment cycle once daily. Overall, 33 patients received alpelisib. Dose‐limiting toxicities were observed in 2 patients in the escalation part (at 400 mg/day) and 1 patient in the expansion part (at 350 mg/day). The RP2D of alpelisib was determined as 350 mg/day based on overall safety profile in the dose escalation part and previous data from a Western population; the MTD was not determined. The most common all‐grade treatment‐suspected adverse events were hyperglycemia and maculopapular rash (48.5% each) and diarrhea (45.5%). The PK of alpelisib in the Japanese population was similar to that reported in the Western population. The overall response rate, disease control rate, and median progression‐free survival at 350 mg/day were 3%, 57.6%, and 3.4 months, respectively. Alpelisib as single agent showed a favorable safety profile and encouraging preliminary efficacy in Japanese patients with advanced solid tumors. This phase I study showed that alpelisib, an α‐specific PI3K inhibitor, as a single agent showed a favorable safety profile and encouraging preliminary efficacy in Japanese patients with advanced solid tumors. [ABSTRACT FROM AUTHOR]

Purpose: Activation of the phosphoinositide 3-kinase (PI3K) pathway is an important resistance mechanism to anti-HER2 therapies. This study aimed to assess the safety and activity of alpelisib (a PI3Kα isoform-specific inhibitor) with T-DM1 in trastuzumab- and taxane-resistant HER2-positive MBC.Methods: Patients with HER2-positive MBC that had progressed on trastuzumab-based therapy were treated with alpelisib daily and T-DM1 3.6 mg/kg every 3 weeks. The dose-limiting toxicity (DLT), maximum tolerated dose (MTD), adverse events, overall response rate (ORR), and clinical benefit rate (CBR = CR + PR + SD > 6 months) were assessed with descriptive statistics. Progression-free survival (PFS) was calculated by the Kaplan-Meier method.Results: Seventeen patients were enrolled with a median of 3 prior therapies for metastatic disease. The DLT was a maculopapular rash and MTD was 250 mg alpelisib daily. The most frequently occurring toxicities included fatigue, rash, gastrointestinal side effects, thrombocytopenia, anemia, elevated liver enzymes, and hyperglycemia. Fourteen patients were evaluable for response with an ORR of 43%. In patients with prior treatment and progression on T-DM1 (n = 10), the ORR was 30%. The CBR was 71% in evaluable patients and 60% in those with prior T-DM1. The median PFS was 8.1 months.Conclusions: The combination of alpelisib and T-DM1 is tolerable and demonstrates activity in trastuzumab-resistant HER2-positive MBC. Furthermore, activity was observed in T-DM1-resistant disease. These data suggest that PIK3CA inhibition targets an important resistance pathway to anti-HER2 therapy, providing rationale for further study of PI3K inhibition in refractory HER2-positive MBC to validate these results. [ABSTRACT FROM AUTHOR]