Elena Geuna

Overcoming endocrine resistance in metastatic breast cancer: Current evidence and future directions

About 75% of all breast cancers are estrogen receptor (ER)-positive. They generally have a more favorable clinical behavior, prognosis, and pattern of recurrence, and endocrine therapy forms the backbone of treatment. Anti-estrogens (such as tamoxifen and fulvestrant) and aromatase inhibitors (such as anastrozole, letrozole, and exemestane) can effectively control the disease and induce tumor responses in a large proportion of patients. However, the majority of patients progress during endocrine therapy (acquired resistance) and a proportion of patients may fail to respond to initial therapy (de novo resistance). Endocrine resistance is therefore of clinical concern and there is great interest in strategies that delay or circumvent it. A deeper knowledge of the molecular mechanisms that drive endocrine resistance has recently led to development of new strategies that have the promise to effectively overcome it. Many resistance mechanisms have been described, and the crosstalk between ER and growth factor receptor signaling pathways seems to represent one of the most relevant. Compounds that are able to inhibit key elements of these pathways and restore endocrine sensitivity have been studied and more are currently under development. The aim of this review is to summarize the molecular pathophysiology of endocrine resistance in breast cancer and its impact on current clinical management.

The neutrophil–lymphocyte ratio and its utilisation for the management of cancer patients in early clinical trials

Background:Inflammation is critical to the pathogenesis and progression of cancer, with a high neutrophil–lymphocyte ratio (NLR) associated with poor prognosis. The utility of studying NLR in early clinical trials is unknown.Methods:This retrospective study evaluated 1300 patients treated in phase 1 clinical trials between July 2004 and February 2014 at the Royal Marsden Hospital (RMH), UK. Data were collected on patient characteristics and baseline laboratory parameters.Results:The test cohort recruited 300 patients; 53% were female, 35% ECOG 0 and 64% ECOG 1. RMH score was 0–1 in 66% and 2–3 in 34%. The median NLR was 3.08 (IQR 2.06–4.49). Median OS for the NLR quartiles was 10.5 months for quartile-1, 10.3 months for quartile-2, 7.9 months for quartile-3 and 6.5 months for quartile-4 (P<0.0001). Univariate analysis identified RMH score (HR=0.55, P<0.0001), ECOG (HR=0.62, P=0.002) and neutrophils (HR=0.65, P=0.003) to be associated with OS. In multivariate analysis, adjusting for RMH score, ECOG, neutrophils and tumour type, NLR remained significantly associated with OS (P=0.002), with no association with therapeutic steroid use. These results were validated in a further 1000 cancer patients. In the validation cohort, NLR was able to discriminate for OS (P=0.004), as was the RMH score. This was further improved on in the RMH score+NLR50 and RMH score+Log10NLR models, with an optimal NLR cutoff of 3.0.Conclusions:NLR is a validated independent prognostic factor for OS in patients treated in phase 1 trials. Combining the NLR with the RMH score improves the discriminating ability for OS.

Buparlisib , an oral pan-PI3K inhibitor for the treatment of breast cancer

Introduction: Deregulation of the phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) intracellular signaling pathway is common in breast cancer (BC) and has been found to be potentially implicated in resistance to endocrine and anti-HER2 therapies. Targeting the PI3K/Akt/mTOR pathway may remove this inhibition and restore sensitivity to these compounds. Buparlisib (BKM120) is a potent oral pan-class I PI3K inhibitor that is being extensively evaluated in multiple tumor types. Areas covered: This review briefly summarizes the pharmacodynamics and pharmacokinetics of buparlisib, focusing on preclinical and clinical data in BC and on ongoing randomized trials. Expert opinion: Overall, buparlisib is a safe and tolerable drug and, despite its peculiar toxicity profile, it is suitable for studies in combination with other anticancer agents in BC. Early-phase clinical trials in BC have provided evidence of antitumor activity. Several trials are being conducted in all the biological subsets of BC, including combinations with endocrine therapy, anti-HER2 agents, PARP-inhibitors and chemotherapy. While clinical results are eagerly awaited, biological material suitable for both genomic and non-genomic analyses is being collected. The authors expect an intense investigation of the potential biomarkers that explain response or resistance to buparlisib and inspire strategies to rationally explore the therapeutic potential of this drug.

Higher Risk of Infections with PI3K–AKT–mTOR Pathway Inhibitors in Patients with Advanced Solid Tumors on Phase I Clinical Trials

Purpose: Novel antitumor therapies against the PI3K–AKT–mTOR pathway are increasingly used to treat cancer, either as single agents or in combination with chemotherapy or other targeted therapies. Although these agents are not known to be myelosuppressive, an increased risk of infection has been reported with rapamycin analogues. However, the risk of infection with new inhibitors of this pathway such as PI3K, AKT, mTORC 1/2, or multikinase inhibitors is unknown. Experimental Design: In this retrospective case–control study, we determined the incidence of infection in a group of 432 patients who were treated on 15 phase I clinical trials involving PI3K–AKT–mTOR pathway inhibitors (cases) versus a group of 100 patients on 10 phase I clinical trials of single agent non-PI3K–AKT–mTOR pathway inhibitors (controls) which did not involve conventional cytotoxic agents. We also collected data from 42 patients who were treated with phase I trials of combinations of PI3K–AKT–mTOR inhibitors and MEK inhibitors and 24 patients with combinations of PI3K–AKT–mTOR inhibitors and cytotoxic chemotherapies. Results: The incidence of all grade infection was significantly higher with all single-agent PI3K–AKT–mTOR inhibitors compared with the control group [27% vs. 8%, respectively, OR, 4.26; 95% confidence intervals (CI), 1.9–9.1, P = 0.0001]. The incidence of grade 3 and 4 infection was also significantly higher with PI3K–AKT–mTOR inhibitors compared with the control group (10.3% vs. 3%, OR, 3.74; 95% CI, 1.1–12.4; P = 0.02). Also, the combination of PI3K–AKT–mTOR inhibitors and chemotherapy was associated with a significantly higher incidence of all grade (OR, 4.79; 95% CI, 2.0–11.2; P = 0.0001) and high-grade (OR, 2.87; 95% CI, 1.0–7.6; P = 0.03) infection when compared with single-agent PI3K–AKT–mTOR inhibitors. Conclusions: Inhibitors of the PI3K–AKT–mTOR pathway can be associated with a higher risk of infection. Combinations of PI3K–AKT–mTOR inhibitors and cytotoxic chemotherapy significantly increase the risk of infection. This should be taken into consideration during the design and conduct of trials involving PI3K–AKT–mTOR pathway inhibitors, particularly when combined with chemotherapy or myelosuppressive agents. Clin Cancer Res; 21(8); 1869–76. ©2015 AACR.

A First-in-Human, Phase I, Dose-Escalation Study of TAK-117, a Selective PI3Kα Isoform Inhibitor, in Patients with Advanced Solid Malignancies.

Purpose: To evaluate the safety, MTD, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of TAK-117 (MLN1117/INK1117), an investigational PI3Kα-selective inhibitor, in patients with advanced solid tumors. Experimental Design: Seventy-one patients received oral TAK-117 once daily [100–300 mg (n = 24)] or 3 days per week [Monday–Wednesday–Friday (MWF), 200–1,200 mg (n = 27); Monday–Tuesday–Wednesday (MTuW), 200–900 mg (n = 20)], in 21-day cycles. Dose escalation proceeded via a 3 + 3 design. Results: TAK-117 once-daily dosing was associated with dose-limiting grade ≥3 alanine/aspartate aminotransferase (ALT/AST) elevations, resulting in a narrow range of tolerable doses (100–150 mg once daily). With MWF/MTuW dosing, no dose-limiting ALT/AST elevations occurred until the MTD of 900 mg; total weekly dose was 2.6-fold that of 150 mg once daily. Drug-related grade ≥3 adverse events occurred in 25%/22%/35% (including hyperglycemia in 0%/7%/15%) of once-daily/MWF/MTuW patients. TAK-117 (100–1,200 mg) exhibited moderately fast oral absorption, a generally dose proportional increase in exposure, and plasma half-life of approximately 11 hours. Total weekly exposures with 900 mg MWF/MTuW dosing were approximately 4 times greater than with 150 mg once daily. Skin pS6 expression was suppressed at ≥200 mg. There were 3/1/0 partial responses (once daily/MWF/MTuW) and 5/7/5 patients had stable disease lasting ≥3 months (all PIK3CA mutated). Conclusions: Intermittent dosing of TAK-117 had an acceptable safety profile and enabled higher doses and total weekly exposures versus once-daily dosing. Although the potential for TAK-117 as single-agent therapy appears limited, further evaluation in combination approaches for advanced solid tumors is warranted. Clin Cancer Res; 23(17); 5015–23. ©2017 AACR.

Complications of hyperglycaemia with PI3K–AKT–mTOR inhibitors in patients with advanced solid tumours on Phase I clinical trials

Background:PI3K–AKT–mTOR inhibitors (PAMi) are promising anticancer treatments. Hyperglycaemia is a mechanism-based toxicity of these agents and is becoming increasingly important with their use in larger numbers of patients.Methods:Retrospective case-control study comparing incidence and severity of hyperglycaemia (all grades) between a case group of 387 patients treated on 18 phase I clinical trials with PAMi (78 patients with PI3Ki, 138 with mTORi, 144 with AKTi and 27 with PI3K/mTORi) and a control group of 109 patients treated on 10 phase I clinical trials with agents not directly targeting the PAM pathway. Diabetic patients were excluded in both groups.Results:The incidence of hyperglycaemia was not significantly different between cases and controls (86.6% vs 80.7%, respectively, P=0.129). However, high grade (grade 3–4) hyperglycaemia was more frequent in the PAMi group than in controls (6.7% vs 0%, respectively, P=0.005). The incidence of grade 3–4 hyperglycaemia was greater with AKT and multikinase inhibitors compared with other PAMi (P<0.001). All patients with high-grade hyperglycaemia received antihyperglycemic treatment and none developed severe metabolic complications (diabetic ketoacidosis or hyperosmolar hyperglycemic nonketotic state). High-grade hyperglycaemia was the cause of permanent PAMi discontinuation in nine patients.Conclusions:PI3K–AKT–mTOR inhibitors are associated with small (6.7%) but statistically significant increased risk of high-grade hyperglycaemia compared with non-PAM targeting agents. However, PAMi-induced hyperglycaemia was not found to be associated with severe metabolic complications in this non-diabetic population of patients with advanced cancers.

Clinical utility of exemestane in the treatment of breast cancer.

Breast cancer is the most prevalent cancer in women, causing a significant mortality worldwide. Different endocrine strategies are available for the treatment of hormone-sensitive breast cancer, including antiestrogen tamoxifen and fulvestrant, as well as third-generation aromatase inhibitors (AIs), such as letrozole, anastrozole, and exemestane. In this review, we will focus on exemestane, its clinical use, and its side effects. Exemestane is a steroidal third-generation AI now used in all treatment settings for breast cancer. In the metastatic disease, it has been extensively investigated as the first-, second-, and further-line treatment and it is now registered for the treatment of postmenopausal women with advanced estrogen-receptor-positive breast cancer whose disease has progressed following antiestrogen therapy. A potential lack of cross-resistance with nonsteroidal AIs has been described, giving additional therapeutic opportunities in sequences of endocrine agents. Exemestane is also approved for the adjuvant treatment of postmenopausal early breast cancer, either as upfront monotherapy for 5 years, as a switch following 2–3 years of tamoxifen, or as extended therapy beyond 5 years of adjuvant treatment. New promising data also showed a beneficial effect in young premenopausal early breast cancer patients, when administered together with ovarian suppression. Interesting results have also emerged when exemestane has been investigated as neodjuvant treatment as well as preventive agent in healthy women at high risk for breast cancer. Exemestane is generally well tolerated, with a side effect profile similar to that of other AIs, including menopausal symptoms, arthralgia, and bone loss. In conclusion, exemestane can be considered an effective and well-tolerated endocrine treatment option for all stages of breast cancer.

Baseline clinical predictors of antitumor response to the PARP inhibitor olaparib in germline BRCA1/2 mutated patients with advanced ovarian cancer

Background The PARP inhibitor olaparib was recently granted Food and Drug Administration (FDA) accelerated approval in patients with advanced BRCA1/2 mutation ovarian cancer. However, antitumor responses are observed in only approximately 40% of patients and the impact of baseline clinical factors on response to treatment remains unclear. Although platinum sensitivity has been suggested as a marker of response to PARP inhibitors, patients with platinum-resistant disease still respond to olaparib. Results 108 patients with advanced BRCA1/2 mutation ovarian cancers were included. The interval between the end of the most recent platinum chemotherapy and PARPi (PTPI) was used to predict response to olaparib independent of conventional definition of platinum sensitivity. RECIST complete response (CR) and partial response (PR) rates were 35% in patients with platinum-sensitive versus 13% in platinum-resistant (p<0.005). Independent of platinum sensitivity status, the RECIST CR/PR rates were 42% in patients with PTPI greater than 52 weeks and 18% in patients with PTPI less than 52 weeks (p=0.016). No association was found between baseline clinical factors such as FIGO staging, debulking surgery, BRCA1 versus BRCA2 mutations, prior history of breast cancer and prior chemotherapy for breast cancer, and the response to olaparib. Methods We conducted an international multicenter retrospective study to investigate the association between baseline clinical characteristics of patients with advanced BRCA1/2 mutation ovarian cancers from eight different cancer centers and their antitumor response to olaparib. Conclusion PTPI may be used to refine the prediction of response to PARP inhibition based on the conventional categorization of platinum sensitivity.

New and developing chemical pharmacotherapy for treating hormone receptor-positive/HER2-negative breast cancer

ABSTRACT Introduction: Endocrine therapy is the mainstay of treatment for a substantial proportion of hormone receptor positive (HR+) breast cancer (BC). Indeed, patients with metastatic disease not immediately life threatening may experience long disease control across several lines of endocrine therapy. The major limitation of this therapeutic approach is primary or acquired resistance. A better understanding of endocrine resistance has resulted in newer targeted agents to be added to endocrine therapy. Areas covered: This review highlights new findings in the treatment of HR+/HER2- BC, with a particular focus on new drugs from phase 3 development onwards. Expert opinion: Combining endocrine therapy with agents targeting putative mechanisms of endocrine resistance is a newer treatment paradigm in HR+ BC. Adding a biologically targeted agent to endocrine therapy results in improved response rate, and clinical benefit rate, and prolonged progression-free survival. A clear advantage in overall survival has not yet been reported. Combination therapy allows to delay chemotherapy but increases toxicities and costs, which are critical factors in decision making in the clinical practice. Moreover, identification and validation of biomarkers of response are needed. Ongoing and future trials should elucidate the role of these compounds in the treatment of HR+/HER2- BC.

Linifanib: current status and future potential in cancer therapy.

Angiogenesis is one of the major mechanisms controlling tumor proliferation and metastatic spreading. Targeting of pro-angiogenic factors and their downstream effectors represents an appealing therapeutic option in the treatment of different cancer types. Linifanib (ABT-869) is a novel tyrosine-kinase inhibitor (TKI) inhibitor and its anti-angiogenic activity has been explored in numerous clinical trials. Here, we review preclinical development of linifanib focusing on its pharmacodynamic and pharmacokinetic characteristics and briefly summarize its evaluation in clinical trials. Linifanib selectively targets VEGFR and PDGFR and has low off-target inhibitory activity. Preclinical and early-phase trials have been showing promising efficacy results However, although signals of anti-tumor activity have been proven in some malignancies, linifanib late-phase development has been facing some challenges due to limited efficacy and increased toxicities. New strategies aimed at finding biomarkers of response and minimizing toxicities are needed to allow the further development of a promising compound.