In this single-group, phase 2 study, the use of trastuzumab deruxtecan resulted in a response in 60% of women with HER2-positive advanced breast cancer who had received a median of six previous lines ...of therapy. The drug was associated with myelosuppression and gastrointestinal toxicity; interstitial lung disease was reported in 13.6% of the patients.
More than half of breast cancers express low levels of HER2. In a phase 3 trial, the antibody–drug conjugate trastuzumab deruxtecan resulted in longer survival than the physician’s choice of ...chemotherapy among patients with HER2-low breast cancer.
SummaryBackgroundTrastuzumab duocarmazine is a novel HER2-targeting antibody–drug conjugate comprised of trastuzumab covalently bound to a linker drug containing duocarmycin. Preclinical studies ...showed promising antitumour activity in various models. In this first-in-human study, we assessed the safety and activity of trastuzumab duocarmazine in patients with advanced solid tumours. MethodsWe did a phase 1 dose-escalation and dose-expansion study. The dose-escalation cohort comprised patients aged 18 years or older enrolled from three academic hospitals in Belgium, the Netherlands, and the UK with locally advanced or metastatic solid tumours with variable HER2 status who were refractory to standard cancer treatment. A separate cohort of patients were enrolled to the dose-expansion phase from 15 hospitals in Belgium, the Netherlands, Spain, and the UK. Dose-expansion cohorts included patients aged 18 years or older with breast, gastric, urothelial, or endometrial cancer with at least HER2 immunohistochemistry 1+ expression and measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST). Trastuzumab duocarmazine was administered intravenously on day 1 of each 3-week cycle. In the dose-escalation phase, trastuzumab duocarmazine was given at doses of 0·3 mg/kg to 2·4 mg/kg (3 + 3 design) until disease progression or unacceptable toxicity. The primary endpoint of the dose-escalation phase was to assess safety and ascertain the recommended phase 2 dose, which would be the dose used in the dose-expansion phase. The primary endpoint of the dose-expansion phase was the proportion of patients achieving an objective response (complete response or partial response), as assessed by the investigator using RECIST version 1.1. This ongoing study is registered with ClinicalTrials.gov, number NCT02277717, and is fully recruited. FindingsBetween Oct 30, 2014, and April 2, 2018, 39 patients were enrolled and treated in the dose-escalation phase and 146 patients were enrolled and treated in the dose-expansion phase. One dose-limiting toxic effect (death from pneumonitis) occurred at the highest administered dose (2·4 mg/kg) in the dose-escalation phase. One further death occurred in the dose-escalation phase (1·5 mg/kg cohort) due to disease progression, which was attributed to general physical health decline. Grade 3–4 treatment-related adverse events reported more than once in the dose-escalation phase were keratitis (n=3) and fatigue (n=2). Based on all available data, the recommended phase 2 dose was set at 1·2 mg/kg. In the dose-expansion phase, treatment-related serious adverse events were reported in 16 (11%) of 146 patients, most commonly infusion-related reactions (two 1%) and dyspnoea (two 1%). The most common treatment-related adverse events (grades 1–4) were fatigue (48 33% of 146 patients), conjunctivitis (45 31%), and dry eye (45 31%). Most patients (104 71% of 146) had at least one ocular adverse event, with grade 3 events reported in ten (7%) of 146 patients. No patients died from treatment-related adverse events and four patients died due to disease progression, which were attributed to hepatic failure (n=1), upper gastrointestinal haemorrhage (n=1), neurological decompensation (n=1), and renal failure (n=1). In the breast cancer dose-expansion cohorts, 16 (33%, 95% CI 20·4–48·4) of 48 assessable patients with HER2-positive breast cancer achieved an objective response (all partial responses) according to RECIST. Nine (28%, 95% CI 13·8–46·8) of 32 patients with HER2-low, hormone receptor-positive breast cancer and six (40%, 16·3–67·6) of 15 patients with HER2-low, hormone receptor-negative breast cancer achieved an objective response (all partial responses). Partial responses were also observed in one (6%, 95% CI 0·2–30·2) of 16 patients with gastric cancer, four (25%, 7·3–52·4) of 16 patients with urothelial cancer, and five (39%, 13·9–68·4) of 13 patients with endometrial cancer. InterpretationTrastuzumab duocarmazine shows notable clinical activity in heavily pretreated patients with HER2-expressing metastatic cancer, including HER2-positive trastuzumab emtansine-resistant and HER2-low breast cancer, with a manageable safety profile. Further investigation of trastuzumab duocarmazine for HER2-positive breast cancer is ongoing and trials for HER2-low breast cancer and other HER2-expressing cancers are in preparation. FundingSynthon Biopharmaceuticals.
CDK4/6 inhibitors combined with endocrine therapy have demonstrated higher antitumor activity than endocrine therapy alone for the treatment of advanced estrogen receptor-positive breast cancer. Some ...of these tumors are de novo resistant to CDK4/6 inhibitors and others develop acquired resistance. Here, we show that p16 overexpression is associated with reduced antitumor activity of CDK4/6 inhibitors in patient-derived xenografts (n = 37) and estrogen receptor-positive breast cancer cell lines, as well as reduced response of early and advanced breast cancer patients to CDK4/6 inhibitors (n = 89). We also identified heterozygous RB1 loss as biomarker of acquired resistance and poor clinical outcome. Combination of the CDK4/6 inhibitor ribociclib with the PI3K inhibitor alpelisib showed antitumor activity in estrogen receptor-positive non-basal-like breast cancer patient-derived xenografts, independently of PIK3CA, ESR1 or RB1 mutation, also in drug de-escalation experiments or omitting endocrine therapy. Our results offer insights into predicting primary/acquired resistance to CDK4/6 inhibitors and post-progression therapeutic strategies.
Treatment options for triple-negative breast cancer remain limited. Activation of the PI3K pathway via loss of PTEN and/or INPP4B is common. Buparlisib is an orally bioavailable, pan-class I PI3K ...inhibitor. We evaluated the safety and efficacy of buparlisib in patients with metastatic triple-negative breast cancer.
This was a single-arm phase 2 study enrolling patients with triple-negative metastatic breast cancer. Patients were treated with buparlisib at a starting dose of 100 mg daily. The primary endpoint was clinical benefit, defined as confirmed complete response (CR), partial response (PR), or stable disease (SD) for ≥ 4 months, per RECIST 1.1. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and toxicity. A subset of patients underwent pre- and on-treatment tumor tissue biopsies for correlative studies.
Fifty patients were enrolled. Median number of cycles was 2 (range 1-10). The clinical benefit rate was 12% (6 patients, all SD ≥ 4 months). Median PFS was 1.8 months (95% confidence interval CI 1.6-2.3). Median OS was 11.2 months (95% CI 6.2-25). The most frequent adverse events were fatigue (58% all grades, 8% grade 3), nausea (34% all grades, none grade 3), hyperglycemia (34% all grades, 4% grade 3), and anorexia (30% all grades, 2% grade 3). Eighteen percent of patients experienced depression (12% grade 1, 6% grade 2) and anxiety (10% grade 1, 8% grade 2). Alterations in PIK3CA/AKT1/PTEN were present in 6/27 patients with available targeted DNA sequencing (MSK-IMPACT), 3 of whom achieved SD as best overall response though none with clinical benefit ≥ 4 months. Of five patients with paired baseline and on-treatment biopsies, reverse phase protein arrays (RPPA) analysis demonstrated reduction of S6 phosphorylation in 2 of 3 patients who achieved SD, and in none of the patients with progressive disease.
Buparlisib was associated with prolonged SD in a very small subset of patients with triple-negative breast cancer; however, no confirmed objective responses were observed. Downmodulation of key nodes in the PI3K pathway was observed in patients who achieved SD. PI3K pathway inhibition alone may be insufficient as a therapeutic strategy for triple-negative breast cancer.
NCT01790932 . Registered on 13 February 2013; NCT01629615 . Registered on 27 June 2012.
SummaryBackgroundEndocrine therapy-based neoadjuvant treatment for luminal breast cancer allows efficient testing of new combinations before surgery. The activation of the ...phosphatidylinositol-3-kinase (PI3K) pathway is a known mechanism of resistance to endocrine therapy. Taselisib is an oral, selective PI3K inhibitor with enhanced activity against PIK3CA-mutant cancer cells. The LORELEI trial tested whether taselisib in combination with letrozole would result in an increased proportion of objective responses and pathological complete responses. MethodsIn this multicentre, randomised, double-blind, parallel-cohort, placebo-controlled phase 2, study, we enrolled postmenopausal women (aged ≥18 years) with histologically confirmed, oestrogen receptor (ER)-positive, HER2-negative, stage I–III, operable breast cancer, from 85 hospitals in 22 countries worldwide. To be eligible, patients had have an Eastern Cooperative Oncology Group (ECOG) performance status 0–1, adequate organ function, and had to have evaluable tumour tissue for PIK3CA genotyping. Patients were randomly assigned (1:1) by means of a permuted block algorithm (block size of four) via an interactive voice or web-based response system, to receive letrozole (2·5 mg/day orally, continuously) with either 4 mg of oral taselisib or placebo (on a 5 days-on, 2 days-off schedule) for 16 weeks, followed by surgery. Randomisation was stratified by tumour size and nodal status. Site staff, patients, and the sponsor were masked to treatment assignment. Coprimary endpoints were the proportion of patients who achieved an objective response by centrally assessed breast MRI and a locally assessed pathological complete response in the breast and axilla (ypT0/Tis, ypN0) at surgery in all randomly assigned patients and in patients with PIK3CA-mutant tumours. Analyses were done in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02273973, and is closed to accrual. FindingsBetween Nov 12, 2014, and Aug 12, 2016, 334 participants were enrolled and randomly assigned to receive letrozole and placebo (n=168) or letrozole and taselisib (n=166). Median follow-up was 4·9 months (IQR 4·7–5·1). The study met one of its primary endpoints: the addition of taselisib to letrozole was associated with a higher proportion of patients achieving an objective response in all randomly assigned patients (66 39% of 168 patients in the placebo group vs 83 50% of 166 in the taselisib group; odds ratio OR 1·55, 95% CI 1·00–2·38; p=0·049) and in the PIK3CA-mutant subset (30 38% of 79 vs 41 56% of 73; OR 2·03, 95% CI 1·06–3·88; p=0·033). No significant differences were observed in pathological complete response between the two groups, either in the overall population (three 2% of 166 in the taselisib group vs one 1% of 168 in the placebo group; OR 3·07 95% CI 0·32–29·85, p=0·37) or in the PIK3CA-mutant cohort (one patient 1%) vs none 0%; OR not estimable, p=0·48). The most common grade 3–4 adverse events in the taselisib group were gastrointestinal (13 8% of 167 patients), infections (eight 5%), and skin–subcutaneous tissue disorders (eight 5%). In the placebo group, four (2%) of 167 patients had grade 3 or worse vascular disorders, two (1%) had gastrointestinal disorders, and two (1%) patients had grade 3 or worse infections and infestations. There was no grade 4 hyperglycaemia and grade 3 cases were asymptomatic. Serious adverse events were more common in the taselisib group (eight 5% patients with infections and seven 4% with gastrointestinal effects) than in the placebo group (one 1% patient each with grade 3 postoperative wound and haematoma infection, grade 4 hypertensive encephalopathy, grade 3 acute cardiac failure, and grade 3 breast pain). One death occurred in the taselisib group, which was not considered to be treatment-related. InterpretationThe increase in the proportion of patients who achieved an objective response from the addition of taselisib to endocrine therapy in a neoadjuvant setting is consistent with the clinical benefit observed in hormone receptor-positive, HER2-negative, metastatic breast cancer. FundingGenentech and F Hoffmann-La Roche.
Purpose
In LOTUS (NCT02162719), adding the oral AKT inhibitor ipatasertib to first-line paclitaxel for locally advanced/metastatic triple-negative breast cancer (aTNBC) improved progression-free ...survival (PFS; primary endpoint), with an enhanced effect in patients with
PIK3CA/AKT1/PTEN
-altered tumors (FoundationOne next-generation sequencing NGS assay). We report final overall survival (OS) results.
Methods
Eligible patients had measurable previously untreated aTNBC. Patients were stratified by prior (neo)adjuvant therapy, chemotherapy-free interval, and tumor immunohistochemistry PTEN status, and were randomized 1:1 to paclitaxel 80 mg/m
2
(days 1, 8, 15) plus ipatasertib 400 mg or placebo (days 1–21) every 28 days until disease progression or unacceptable toxicity. OS (intent-to-treat ITT, immunohistochemistry PTEN-low, and PI3K/AKT pathway-activated NGS
PIK3CA/AKT1/PTEN
-altered populations) was a secondary endpoint.
Results
Median follow-up was 19.0 versus 16.0 months in the ipatasertib–paclitaxel versus placebo–paclitaxel arms, respectively. In the ITT population (
n
= 124), median OS was numerically longer with ipatasertib–paclitaxel than placebo–paclitaxel (hazard ratio 0.80, 95% CI 0.50–1.28; median 25.8 vs 16.9 months, respectively; 1-year OS 83% vs 68%). Likewise, median OS favored ipatasertib–paclitaxel in the PTEN-low (
n
= 48; 23.1 vs 15.8 months; hazard ratio 0.83) and
PIK3CA/AKT1/PTEN
-altered (
n
= 42; 25.8 vs 22.1 months; hazard ratio 1.13) subgroups. The ipatasertib–paclitaxel safety profile was unchanged.
Conclusions
Final OS results show a numerical trend favoring ipatasertib–paclitaxel and median OS exceeding 2 years with ipatasertib–paclitaxel. Overall, results are consistent with the reported PFS benefit; interpretation within biomarker-defined subgroups is complicated by small sample sizes and TNBC heterogeneity.
Liquid biopsy has proven valuable in identifying individual genetic alterations; however, the ability of plasma ctDNA to capture complex tumor phenotypes with clinical value is unknown. To address ...this question, we have performed 0.5X shallow whole-genome sequencing in plasma from 459 patients with metastatic breast cancer, including 245 patients treated with endocrine therapy and a CDK4/6 inhibitor (ET + CDK4/6i) from 2 independent cohorts. We demonstrate that machine learning multi-gene signatures, obtained from ctDNA, identify complex biological features, including measures of tumor proliferation and estrogen receptor signaling, similar to what is accomplished using direct tumor tissue DNA or RNA profiling. More importantly, 4 DNA-based subtypes, and a ctDNA-based genomic signature tracking retinoblastoma loss-of-heterozygosity, are significantly associated with poor response and survival outcome following ET + CDK4/6i, independently of plasma tumor fraction. Our approach opens opportunities for the discovery of additional multi-feature genomic predictors coming from ctDNA in breast cancer and other cancer-types.
Purpose
Neoadjuvant clinical trials with dual HER2 blockade with pertuzumab and trastuzumab plus chemotherapy demonstrated high rates of pathological complete response (pCR) in HER2-positive early ...breast cancer (BC). We investigated whether the benefit on pCR seen in clinical trials is confirmed in a real-world setting.
Methods
Multicenter, retrospective study in patients with HER2-positive early BC receiving neoadjuvant treatment with pertuzumab and trastuzumab in routine clinical practice (
n
= 243). The primary endpoint was total pCR (tpCR) (ypT0/is ypN0).
Results
A total of 243 evaluable patients were included. Pertuzumab and trastuzumab were combined with anthracyclines and taxanes in 74.1% of patients, with single-agent taxane in 11.1% of patients and with platinum-based chemotherapy (CT) in 14.4% of patients. The tpCR rate was 66.4%:71% with anthracyclines and taxanes, 59.3% with single-agent taxane, and 48.6% with platinum-based combinations. The tpCR rate was higher among patients with hormone receptor (HR)-negative tumors (80.9%) vs HR-positive tumors (55.4%) (
p
< 0.001). A pCR in the breast (ypT0/is) was achieved in 67.6% of patients. Of 143 patients who showed radiological complete response (rCR) (62%), 112 (78.3%) patients also achieved tpCR. Assessment of rCR by magnetic resonance imaging (MRI) showed the highest negative predictive value (NPV) for predicting tpCR (83.5%). Breast-conserving surgery was performed in 58.7% of patients. Grade 3 and grade 4 toxicities were reported in 33 (18.2%) and 12 (6.6%) patients, respectively. No toxicity leading to death was reported.
Conclusions
This real-world analysis shows that neoadjuvant pertuzumab, trastuzumab, and chemotherapy achieve comparable or even higher rates of tpCR than those seen in clinical trials. The pCR benefit is higher in HR-negative tumors. The assessment of rCR by MRI showed the highest ability for predicting pCR. In addition, this neoadjuvant strategy confers an acceptable safety profile.
Breast cancer (BC) with expression of the estrogen receptor (ER) and/or progesterone receptor (PR) protein and with overexpression/amplification of the human epidermal growth factor receptor 2 ...(HER2), termed hormone receptor-positive (HR+)/HER2+ BC, represents ∼10% of all BCs in the United States. HR+/HER2+ BC includes HER2+ BCs that are ER+, PR+, or both ER+ and PR+ (triple-positive BC). Although the current guideline-recommended treatment combination of anti-HER2 monoclonal antibodies plus chemotherapy is an effective first-line therapy for many patients with HER2+ advanced disease, intratumoral heterogeneity within the HR+/HER2+ subtype and differences between the HR+/HER2+ subtype and the HR−/HER2+ subtype suggest that other targeted combinations could be investigated in randomized clinical trials for patients with HR+/HER2+ BC. In addition, published data indicate that crosstalk between HRs and HER2 can lead to treatment resistance. Dual HR and HER2 pathway targeting has been shown to be a rational approach to effective and well-tolerated therapy for patients with tumors driven by HER2 and HR, as it may prevent development of resistance by blocking receptor pathway crosstalk. However, clinical trial data for such approaches are limited. Treatments to attenuate other signaling pathways involved in receptor crosstalk are also under investigation for inclusion in dual receptor targeting regimens. These include cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, based on the rationale that association of CDK4/6 with cyclin D1 may play a role in resistance to HER2-directed therapies, and others such as phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway inhibitors. Herein, we will review the scientific and clinical rationale for combined receptor blockade targeting HER2 and ER for patients with advanced-stage HR+/HER2+ disease.
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