Implementing Genome-Driven Oncology.

Early successes in identifying and targeting individual oncogenic drivers, together with the increasing feasibility of sequencing tumor genomes, have brought forth the promise of genome-driven oncology care. As we expand the breadth and depth of genomic analyses, the biological and clinical complexity of its implementation will be unparalleled. Challenges include target credentialing and validation, implementing drug combinations, clinical trial designs, targeting tumor heterogeneity, and deploying technologies beyond DNA sequencing, among others. We review how contemporary approaches are tackling these challenges and will ultimately serve as an engine for biological discovery and increase our insight into cancer and its treatment.

A Biobank of Breast Cancer Explants with Preserved Intra-tumor Heterogeneity to Screen Anticancer Compounds.

The inter- and intra-tumor heterogeneity of breast cancer needs to be adequately captured in pre-clinical models. We have created a large collection of breast cancer patient-derived tumor xenografts (PDTXs), in which the morphological and molecular characteristics of the originating tumor are preserved through passaging in the mouse. An integrated platform combining in vivo maintenance of these PDTXs along with short-term cultures of PDTX-derived tumor cells (PDTCs) was optimized. Remarkably, the intra-tumor genomic clonal architecture present in the originating breast cancers was mostly preserved upon serial passaging in xenografts and in short-term cultured PDTCs. We assessed drug responses in PDTCs on a high-throughput platform and validated several ex vivo responses in vivo. The biobank represents a powerful resource for pre-clinical breast cancer pharmacogenomic studies (http://caldaslab.cruk.cam.ac.uk/bcape), including identification of biomarkers of response or resistance.

The evolving war on cancer.

Building on years of basic scientific discovery, recent advances in the fields of cancer genetics and medicinal chemistry are now converging to revolutionize the treatment of cancer. Starting with serendipitous observations in rare subsets of cancer, a paradigm shift in clinical research is poised to ensure that new molecular insights are rapidly applied to shape emerging cancer therapies. Could this mark a turning point in the "War on Cancer"?

Author Correction: Tumour lineage shapes BRCA-mediated phenotypes.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

A view on drug resistance in cancer.

The problem of resistance to therapy in cancer is multifaceted. Here we take a reductionist approach to define and separate the key determinants of drug resistance, which include tumour burden and growth kinetics; tumour heterogeneity; physical barriers; the immune system and the microenvironment; undruggable cancer drivers; and the many consequences of applying therapeutic pressures. We propose four general solutions to drug resistance that are based on earlier detection of tumours permitting cancer interception; adaptive monitoring during therapy; the addition of novel drugs and improved pharmacological principles that result in deeper responses; and the identification of cancer cell dependencies by high-throughput synthetic lethality screens, integration of clinico-genomic data and computational modelling. These different approaches could eventually be synthesized for each tumour at any decision point and used to inform the choice of therapy.

Tumour lineage shapes BRCA-mediated phenotypes.

Mutations in BRCA1 and BRCA2 predispose individuals to certain cancers1-3, and disease-specific screening and preventative strategies have reduced cancer mortality in affected patients4,5. These classical tumour-suppressor genes have tumorigenic effects associated with somatic biallelic inactivation, although haploinsufficiency may also promote the formation and progression of tumours6,7. Moreover, BRCA1/2-mutant tumours are often deficient in the repair of double-stranded DNA breaks by homologous recombination8-13, and consequently exhibit increased therapeutic sensitivity to platinum-containing therapy and inhibitors of poly-(ADP-ribose)-polymerase (PARP)14,15. However, the phenotypic and therapeutic relevance of mutations in BRCA1 or BRCA2 remains poorly defined in most cancer types. Here we show that in the 2.7% and 1.8% of patients with advanced-stage cancer and germline pathogenic or somatic loss-of-function alterations in BRCA1/2, respectively, selective pressure for biallelic inactivation, zygosity-dependent phenotype penetrance, and sensitivity to PARP inhibition were observed only in tumour types associated with increased heritable cancer risk in BRCA1/2 carriers (BRCA-associated cancer types). Conversely, among patients with non-BRCA-associated cancer types, most carriers of these BRCA1/2 mutation types had evidence for tumour pathogenesis that was independent of mutant BRCA1/2. Overall, mutant BRCA is an indispensable founding event for some tumours, but in a considerable proportion of other cancers, it appears to be biologically neutral-a difference predominantly conditioned by tumour lineage-with implications for disease pathogenesis, screening, design of clinical trials and therapeutic decision-making.

Author Correction: HER kinase inhibition in patients with HER2- and HER3-mutant cancers.

The 'Competing interests' statement of this Article has been updated; please see the accompanying Amendment. The original Article has not been corrected online.

HER kinase inhibition in patients with HER2- and HER3-mutant cancers.

Somatic mutations of ERBB2 and ERBB3 (which encode HER2 and HER3, respectively) are found in a wide range of cancers. Preclinical modelling suggests that a subset of these mutations lead to constitutive HER2 activation, but most remain biologically uncharacterized. Here we define the biological and therapeutic importance of known oncogenic HER2 and HER3 mutations and variants of unknown biological importance by conducting a multi-histology, genomically selected, 'basket' trial using the pan-HER kinase inhibitor neratinib (SUMMIT; clinicaltrials.gov identifier NCT01953926). Efficacy in HER2-mutant cancers varied as a function of both tumour type and mutant allele to a degree not predicted by preclinical models, with the greatest activity seen in breast, cervical and biliary cancers and with tumours that contain kinase domain missense mutations. This study demonstrates how a molecularly driven clinical trial can be used to refine our biological understanding of both characterized and new genomic alterations with potential broad applicability for advancing the paradigm of genome-driven oncology.

Recurrent and functional regulatory mutations in breast cancer.

Genomic analysis of tumours has led to the identification of hundreds of cancer genes on the basis of the presence of mutations in protein-coding regions. By contrast, much less is known about cancer-causing mutations in non-coding regions. Here we perform deep sequencing in 360 primary breast cancers and develop computational methods to identify significantly mutated promoters. Clear signals are found in the promoters of three genes. FOXA1, a known driver of hormone-receptor positive breast cancer, harbours a mutational hotspot in its promoter leading to overexpression through increased E2F binding. RMRP and NEAT1, two non-coding RNA genes, carry mutations that affect protein binding to their promoters and alter expression levels. Our study shows that promoter regions harbour recurrent mutations in cancer with functional consequences and that the mutations occur at similar frequencies as in coding regions. Power analyses indicate that more such regions remain to be discovered through deep sequencing of adequately sized cohorts of patients.

Patient-reported function, health-related quality of life, and symptoms in APHINITY: pertuzumab plus trastuzumab and chemotherapy in HER2-positive early breast cancer.

BACKGROUND: We assessed health-related quality of life (symptoms of therapy/patient functioning/global health status), in APHINITY (pertuzumab/placebo, trastuzumab, and chemotherapy as adjuvant HER2-positive early breast cancer therapy). METHODS: Patients received 1 year/18 cycles of pertuzumab/placebo with trastuzumab and chemotherapy and completed EORTC QLQ-C30 and BR23 questionnaires until 36 months post-randomisation/disease recurrence. Changes ≥10 points from baseline were considered clinically meaningful. RESULTS: 87-97% of patients completed questionnaires. In the pertuzumab versus placebo arms, mean decrease in physical function scores (baseline → end of taxane) was -10.7 (95% CI -11.4, -10.0) versus -10.6 (-11.4, -9.9), mean decrease in global health status was -11.2 (-12.2, -10.2) versus -10.2 (-11.1, -9.2), and mean increase in diarrhoea scores (baseline → end of taxane) was +22.3 (21.0, 23.6) versus +9.2 (8.2, 10.2). Diarrhoea scores remained elevated versus baseline in the pertuzumab arm throughout HER2-targeted treatment (week 25: +13.2; end of treatment: +12.2). Role functioning was maintained in both arms. CONCLUSIONS: Improved invasive disease-free survival achieved by adding pertuzumab to trastuzumab and chemotherapy did not adversely affect the ability to conduct activities of daily living versus trastuzumab and chemotherapy alone. Patient-reported diarrhoea worsened during taxane therapy in both arms, persisting during HER2-targeted treatment in the pertuzumab arm. CLINICALTRIALS.GOV: NCT01358877.

Convergent loss of PTEN leads to clinical resistance to a PI(3)Kα inhibitor.

Broad and deep tumour genome sequencing has shed new light on tumour heterogeneity and provided important insights into the evolution of metastases arising from different clones. There is an additional layer of complexity, in that tumour evolution may be influenced by selective pressure provided by therapy, in a similar fashion to that occurring in infectious diseases. Here we studied tumour genomic evolution in a patient (index patient) with metastatic breast cancer bearing an activating PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha, PI(3)Kα) mutation. The patient was treated with the PI(3)Kα inhibitor BYL719, which achieved a lasting clinical response, but the patient eventually became resistant to this drug (emergence of lung metastases) and died shortly thereafter. A rapid autopsy was performed and material from a total of 14 metastatic sites was collected and sequenced. All metastatic lesions, when compared to the pre-treatment tumour, had a copy loss of PTEN (phosphatase and tensin homolog) and those lesions that became refractory to BYL719 had additional and different PTEN genetic alterations, resulting in the loss of PTEN expression. To put these results in context, we examined six other patients also treated with BYL719. Acquired bi-allelic loss of PTEN was found in one of these patients, whereas in two others PIK3CA mutations present in the primary tumour were no longer detected at the time of progression. To characterize our findings functionally, we examined the effects of PTEN knockdown in several preclinical models (both in cell lines intrinsically sensitive to BYL719 and in PTEN-null xenografts derived from our index patient), which we found resulted in resistance to BYL719, whereas simultaneous PI(3)K p110ß blockade reverted this resistance phenotype. We conclude that parallel genetic evolution of separate metastatic sites with different PTEN genomic alterations leads to a convergent PTEN-null phenotype resistant to PI(3)Kα inhibition.

The hVps34-SGK3 pathway alleviates sustained PI3K/Akt inhibition by stimulating mTORC1 and tumour growth.

We explore mechanisms that enable cancer cells to tolerate PI3K or Akt inhibitors. Prolonged treatment of breast cancer cells with PI3K or Akt inhibitors leads to increased expression and activation of a kinase termed SGK3 that is related to Akt. Under these conditions, SGK3 is controlled by hVps34 that generates PtdIns(3)P, which binds to the PX domain of SGK3 promoting phosphorylation and activation by its upstream PDK1 activator. Furthermore, under conditions of prolonged PI3K/Akt pathway inhibition, SGK3 substitutes for Akt by phosphorylating TSC2 to activate mTORC1. We characterise 14h, a compound that inhibits both SGK3 activity and activation in vivo, and show that a combination of Akt and SGK inhibitors induced marked regression of BT-474 breast cancer cell-derived tumours in a xenograft model. Finally, we present the kinome-wide analysis of mRNA expression dynamics induced by PI3K/Akt inhibition. Our findings highlight the importance of the hVps34-SGK3 pathway and suggest it represents a mechanism to counteract inhibition of PI3K/Akt signalling. The data support the potential of targeting both Akt and SGK as a cancer therapeutic.

A Phase II Trial of Cabozantinib in Hormone Receptor-Positive Breast Cancer with Bone Metastases.

BACKGROUND: We assessed the antitumor activity of cabozantinib, a potent multireceptor oral tyrosine kinase inhibitor, in patients with hormone receptor-positive breast cancer with bone metastases. PATIENTS AND METHODS: In this single-arm multicenter phase II study, patients received an initial starting dose of 100 mg, later reduced to 60 mg, per day. The primary endpoint was the bone scan response rate. Secondary endpoints included objective response rate by RECIST, progression-free survival (PFS), and overall survival (OS). RESULTS: Of 52 women enrolled, 20 (38%) experienced a partial response on bone scan and 6 (12%) had stable disease. Prior to the first repeat bone scan at 12 weeks, 19 (35%) patients discontinued study treatment because of early clinical progression or unacceptable toxicity. RECIST evaluation based on best overall response by computed tomography revealed stable disease in extraosseous tissues in 26 patients (50%) but no complete or partial responses. In 25 patients with disease control on bone scan at 12 weeks, only 3 (12%) patients developed extraosseous progression. The median PFS was 4.3 months, and median OS was 19.6 months. The most common grade 3 or 4 toxicities were hypertension (10%), anorexia (6%), diarrhea (6%), fatigue (4%), and hypophosphatemia (4%). CONCLUSION: Bone scans improved in 38% of patients with metastatic hormone receptor-positive breast cancer and remained stable in an additional 12% for a minimum duration of 12 weeks on cabozantinib. Further investigations should assess the activity of cabozantinib in combination with other hormonal and other breast cancer therapies and determine whether bone scan responses correlate with meaningful antitumor effects. ClinicalTrials.gov identifier. NCT01441947 IMPLICATIONS FOR PRACTICE: Most patients with metastatic hormone receptor-positive (HR+) breast cancer have bone involvement, and many have bone-only disease, which is difficult to evaluate for response. This phase II single-arm study evaluated the clinical activity of the small molecule MET/RET/VEGFR2 inhibitor cabozantinib in patients with metastatic HR+ breast cancer with bone metastases. This study met its primary endpoint, and cabozantinib treatment resulted in a significant bone scan response rate correlating with improved survival. This is the first study to use bone scan response as a primary endpoint in breast cancer. The results support further study of cabozantinib in HR+ breast cancer.

Adjuvant Pertuzumab and Trastuzumab in Early HER2-Positive Breast Cancer.

BACKGROUND: Pertuzumab increases the rate of pathological complete response in the preoperative context and increases overall survival among patients with metastatic disease when it is added to trastuzumab and chemotherapy for the treatment of human epidermal growth factor receptor 2 (HER2)-positive breast cancer. In this trial, we investigated whether pertuzumab, when added to adjuvant trastuzumab and chemotherapy, improves outcomes among patients with HER2-positive early breast cancer. METHODS: We randomly assigned patients with node-positive or high-risk node-negative HER2-positive, operable breast cancer to receive either pertuzumab or placebo added to standard adjuvant chemotherapy plus 1 year of treatment with trastuzumab. We assumed a 3-year invasive-disease-free survival rate of 91.8% with pertuzumab and 89.2% with placebo. RESULTS: In the trial population, 63% of the patients who were randomly assigned to receive pertuzumab (2400 patients) or placebo (2405 patients) had node-positive disease and 36% had hormone-receptor-negative disease. Disease recurrence occurred in 171 patients (7.1%) in the pertuzumab group and 210 patients (8.7%) in the placebo group (hazard ratio, 0.81; 95% confidence interval [CI], 0.66 to 1.00; P=0.045). The estimates of the 3-year rates of invasive-disease-free survival were 94.1% in the pertuzumab group and 93.2% in the placebo group. In the cohort of patients with node-positive disease, the 3-year rate of invasive-disease-free survival was 92.0% in the pertuzumab group, as compared with 90.2% in the placebo group (hazard ratio for an invasive-disease event, 0.77; 95% CI, 0.62 to 0.96; P=0.02). In the cohort of patients with node-negative disease, the 3-year rate of invasive-disease-free survival was 97.5% in the pertuzumab group and 98.4% in the placebo group (hazard ratio for an invasive-disease event, 1.13; 95% CI, 0.68 to 1.86; P=0.64). Heart failure, cardiac death, and cardiac dysfunction were infrequent in both treatment groups. Diarrhea of grade 3 or higher occurred almost exclusively during chemotherapy and was more frequent with pertuzumab than with placebo (9.8% vs. 3.7%). CONCLUSIONS: Pertuzumab significantly improved the rates of invasive-disease-free survival among patients with HER2-positive, operable breast cancer when it was added to trastuzumab and chemotherapy. Diarrhea was more common with pertuzumab than with placebo. (Funded by F. Hoffmann-La Roche/Genentech; APHINITY ClinicalTrials.gov number, NCT01358877 .).

Early Modulation of Circulating MicroRNAs Levels in HER2-Positive Breast Cancer Patients Treated with Trastuzumab-Based Neoadjuvant Therapy.

Circulating microRNA (ct-miRNAs) are able to identify patients with differential response to HER2-targeted therapy. However, their dynamics are largely unknown. We assessed 752 miRNAs from 52 NeoALTTO patients with plasma pairs prior and two weeks after trastuzumab. Increased levels of ct-miR-148a-3p and ct-miR-374a-5p were significantly associated with pathological complete response (pCR) (p = 0.008 and 0.048, respectively). At a threshold ≥ the upper limit of the 95%CI of the mean difference, pCR resulted 45% (95%CI 24%-68%), and 44% (95%CI 22%-69%) for ct-miR-148a-3p and ct-miR-374a-5p, respectively. Notably, ct-miR-148a-3p retained its predictive value (OR 3.42, 95%CI 1.23-9.46, p = 0.018) in bivariate analysis along with estrogen receptor status. Combined information from ct-miR-148a-3p and ct-miR140-5p, which we previously reported to identify trastuzumab-responsive patients, resulted in greater predictive capability over each other, with pCR of 54% (95%CI 25%-81%) and 0% (95%CI 0%-31%) in ct-miR-148a/ct-miR-140-5p high/present and low/absent, respectively. GO and KEGG analyses showed common enriched terms between the targets of these ct-miRNAs, including cell metabolism regulation, AMPK and MAPK signaling, and HCC progression. In conclusion, early modulated ct-miR-148-3p may inform on the functional processes underlying treatment response, integrate the information from already available predictive biomarkers, and identify patients likely to respond to single agent trastuzumab-based neoadjuvant therapy.

Neoadjuvant letrozole plus taselisib versus letrozole plus placebo in postmenopausal women with oestrogen receptor-positive, HER2-negative, early-stage breast cancer (LORELEI): a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial.

BACKGROUND: Endocrine 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. METHODS: In 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. FINDINGS: Between 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. INTERPRETATION: The 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. FUNDING: Genentech and F Hoffmann-La Roche.

MET activation confers resistance to cetuximab, and prevents HER2 and HER3 upregulation in head and neck cancer.

An understanding of the mechanisms underlying acquired resistance to cetuximab is urgently needed to improve cetuximab efficacy in patients with head and neck squamous cell carcinoma (HNSCC). Here, we present a clinical observation that MET pathway activation constitutes the mechanism of acquired resistance to cetuximab in a patient with HNSCC. Specifically, RNA sequencing and mass spectrometry analysis of cetuximab-sensitive (CetuxSen ) and cetuximab-resistant (CetuxRes ) tumors indicated MET amplification and overexpression in the CetuxRes tumor compared to the CetuxSen lesion. Stimulation of MET in HNSCC cell lines was sufficient to reactivate the MAPK pathway and to confer resistance to cetuximab in vitro and in vivo. In addition to the direct role of MET in reactivation of the MAPK pathway, MET stimulation abrogates the well-known cetuximab-induced compensatory feedback loop of HER2/HER3 expression. Mechanistically, we showed that the overexpression of HER2 and HER3 following cetuximab treatment is mediated by the ETS homologous transcription factor (EHF), and is suppressed by MET/MAPK pathway activation. Collectively, our findings indicate that evaluation of MET and HER2/HER3 in response to cetuximab in HNSCC patients can provide the rationale of successive line of treatment.

Pregnancies during and after trastuzumab and/or lapatinib in patients with human epidermal growth factor receptor 2-positive early breast cancer: Analysis from the NeoALTTO (BIG 1-06) and ALTTO (BIG 2-06) trials.

BACKGROUND: Limited data exist on the safety of using anti-human epidermal growth factor receptor 2 (HER2) targeted agents during pregnancy. To date, only retrospective studies have assessed the prognosis of patients with a pregnancy after prior early breast cancer, with no data in HER2-positive patients. METHODS: The Neoadjuvant Lapatinib and/or Trastuzumab Treatment Optimization (NeoALTTO) trial and the Adjuvant Lapatinib and/or Trastuzumab Treatment Optimization (ALTTO) trial were randomized phase 3 trials for patients with HER2-positive early breast cancer. In both trials, pregnancy information was prospectively collected. Pregnancy outcomes were compared between patients unintentionally exposed to trastuzumab and/or lapatinib during gestation (the exposed group) and those who became pregnant after trastuzumab and/or lapatinib completion (the unexposed group). In the ALTTO trial, disease-free survival (DFS) was compared between pregnant patients and those aged 40 years or younger without a subsequent pregnancy via an extended Cox model with time-varying covariates to account for a guarantee-time bias. RESULTS: Ninety-two patients (12 in the exposed group and 80 in the unexposed group) had a pregnancy: 7 in the NeoALTTO trial and 85 in the ALTTO trial. Seven patients (58.3%) in the exposed group and 10 patients (12.5%) in the unexposed group opted for an induced abortion; in the unexposed group, 10 patients (12.5%) had a spontaneous abortion. No pregnancy/delivery complications were reported for the remaining cases, who successfully completed their pregnancy, with the exception of 1 fetus with trisomy 21 (Down syndrome). No significant difference in DFS (adjusted hazard ratio, 1.12; 95% confidence interval, 0.52-2.42) was observed between young patients with a pregnancy (n = 85) and young patients without a pregnancy (n = 1307). CONCLUSIONS: For patients with HER2-positive early breast cancer, having a pregnancy after treatment completion appears to be safe without compromising fetal outcome or maternal prognosis.

Everolimus plus Exemestane for Hormone Receptor-Positive Advanced Breast Cancer: A PAM50 Intrinsic Subtype Analysis of BOLERO-2.

BACKGROUND: The prognostic and predictive value of the two nonluminal (human epidermal growth factor receptor 2 [HER2]-enriched and basal-like) subtypes within advanced hormone receptor-positive (HR+) breast cancer is currently unknown. MATERIALS AND METHODS: This study retrospectively analyzed 261 tumors (80.7% primary; 19.3% metastatic) from the BOLERO-2 study; BOLERO-2 randomized 724 patients with advanced HR+/HER2-negative breast cancer to everolimus plus exemestane or placebo plus exemestane. Tumors were classified using a PAM50 subtype predictor. Multivariable Cox regression analyses tested the independent prognostic significance of PAM50, and associations between PAM50 subtypes and treatment upon progression-free survival (PFS) were evaluated. RESULTS: Subtype distribution was 46.7% luminal A (n = 122), 21.5% HER2-enriched (n = 56), 15.7% luminal B (n = 41), 14.2% normal-like (n = 37), and 1.9% basal-like (n = 5); HER2-enriched subtypes were more common in metastatic versus primary tumors (32.0% vs. 18.7%; p = .038). Median PFS differences between luminal and nonluminal (6.7 vs. 5.2 months; adjusted hazard ratio, 0.66; 95% confidence interval [CI], 0.47-0.94; p = .020) and HER2-enriched and non-HER2-enriched subtypes (5.2 vs. 6.2 months; adjusted hazard ratio, 1.53; 95% CI, 1.07-2.19; p = .019) were significant. Everolimus plus exemestane significantly improved median PFS versus placebo plus exemestane among patients with HER2-enriched tumors (5.8 vs. 4.1 months; adjusted hazard ratio, 0.49; 95% CI, 0.26-0.90; p = .034); however, the association between HER2-enriched tumors and everolimus benefit was nonsignificant (p = .433). CONCLUSION: The HER2-enriched subtype was identified in a substantial proportion of advanced HR+/HER2-negative breast tumors, and was a consistent biomarker of poor prognosis. Tailored therapies are therefore needed for HER2-enriched tumors in the advanced HR+/HER2-negative breast cancer setting. IMPLICATIONS FOR PRACTICE: Using 261 tumor samples from the BOLERO-2 phase III clinical trial, this study shows that a substantial proportion (20%-30%) of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancers do not have a luminal A or B gene expression profile. This group of patients with nonluminal disease has a poor survival outcome regardless of the addition of everolimus to exemestane. This is the second study that confirms the prognostic value of this biomarker. Overall, these findings indicate a necessity to design novel clinical trials targeting nonluminal disease within HR+/HER2-negative breast cancer.

Immunohistochemical analysis of estrogen receptor in breast cancer with ESR1 mutations detected by hybrid capture-based next-generation sequencing.

Estrogen receptor-α (ER-α), encoded by ESR1, is detected by immunohistochemistry in approximately 70% of invasive breast cancers and serves as a strong predictive biomarker. ESR1-activating mutations in the ligand-binding domain have been reported in up to 35-40% of ER-positive metastatic breast cancers and are associated with endocrine therapy resistance and disease progression. At present, it is unclear whether ESR1 mutations alter the immunohistochemical detection of ER performed in routine clinical practice. In this study, ESR1 mutations in breast cancer were identified utilizing Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT), a Food and Drug Administration-approved hybridization capture-based next-generation sequencing assay. Five hundred and eighty-six breast cancers from patients with locally advanced or metastatic disease were analyzed using MSK-IMPACT in the study period. ESR1 somatic alterations were identified in 67 breast cancer samples from 66 patients. Immunohistochemical analysis of ER, progesterone receptor, and human epidermal growth factor receptor 2 was performed on the primary and treated breast cancers from these patients at the time of diagnosis. Twenty unique ESR1 mutations were identified involving the ligand-binding domain, all in breast cancer samples from patients previously treated with endocrine therapy. The most frequent mutations were D538G (n = 22), Y537S (n = 7), and E380Q (n = 7). All breast cancer samples with an ESR1 mutation were ER-positive by immunohistochemistry. Review of the ER immunohistochemistry in the paired untreated primary tumor and treated tumor from 34 patients showed no detectable change in the ER-positive immunohistochemical status (median percentage of invasive tumor cells with nuclear staining: untreated primary tumor 90%, treated tumor 95%). We conclude that ESR1 mutations do not appreciably diminish ER-positive staining by immunohistochemistry. In addition to standard biomarker testing by immunohistochemistry, the assessment of ESR1 mutations by molecular testing can help guide the clinical management of patients with ER-positive breast cancer in the setting of endocrine resistance and progression of disease.