Adaptive Randomization of Veliparib-Carboplatin Treatment in Breast Cancer

In silico mouse study identifies tumour growth kinetics as biomarkers for the outcome of anti-angiogenic treatment

Angiogenesis is a crucial step in tumour progression, as this process allows tumours to recruit new blood vessels and obtain oxygen and nutrients to sustain growth. Therefore, inhibiting angiogenesis remains a viable strategy for cancer therapy. However, anti-angiogenic therapy has not proved to be effective in reducing tumour growth across a wide range of tumours, and no reliable predictive biomarkers have been found to determine the efficacy of anti-angiogenic treatment. Using our previously established computational model of tumour-bearing mice, we sought to determine whether tumour growth kinetic parameters could be used to predict the outcome of anti-angiogenic treatment. A model trained with datasets from six in vivo mice studies was used to generate a randomized in silico tumour-bearing mouse population. We analysed tumour growth in untreated mice (control) and mice treated with an anti-angiogenic agent and determined the Kaplan–Meier survival estimates based on simulated tumour volume data. We found that the ratio between two kinetic parameters, k₀ and k₁, which characterize the tumour's exponential and linear growth rates, as well as k₁ alone, can be used as prognostic biomarkers of the population survival outcome. Our work demonstrates a robust, quantitative approach for identifying tumour growth kinetic parameters as prognostic biomarkers and serves as a template that can be used to identify other biomarkers for anti-angiogenic treatment.

The Adaptive Platform Trials Coalition. Adaptive platform trials: definition, design, conduct and reporting considerations

Researchers, clinicians, policymakers and patients are increasingly interested in questions about therapeutic interventions that are difficult or costly to answer with traditional, free-standing, parallel-group randomized controlled trials (RCTs). Examples include scenarios in which there is a desire to compare multiple interventions, to generate separate effect estimates across subgroups of patients with distinct but related conditions or clinical features, or to minimize downtime between trials. In response, researchers have proposed new RCT designs such as adaptive platform trials (APTs), which are able to study multiple interventions in a disease or condition in a perpetual manner, with interventions entering and leaving the platform on the basis of a predefined decision algorithm. APTs offer innovations that could reshape clinical trials, and several APTs are now funded in various disease areas. With the aim of facilitating the use of APTs, here we review common features and issues that arise with such trials, and offer recommendations to promote best practices in their design, conduct, oversight and reporting.

Available and emerging molecular markers in the clinical management of breast cancer

Introduction: Biomarker assessment is fundamental to managing patients with invasive breast cancer. While the assessment of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 is mandatory for all invasive breast tumors, recent advances in our understanding of tumor biology have uncovered a growing list of clinically relevant biomarkers. Areas covered: In early-stage breast cancer, we focus on dynamic changes in Ki-67 during neoadjuvant endocrine therapy and multigene prognostic assays to guide adjuvant chemotherapy decisions. In advanced breast cancer, we discuss the techniques and clinical relevance of ESR1 and PIK3CA mutations in cell-free DNA and describe therapeutically targetable germline or somatic alterations, with specific focus on BRCA mutations, microsatellite instability, and NTRK fusions. Expert opinion: Biomarkers influence breast cancer management at every stage of disease. This review summarizes recently identified tissue and blood-based biomarkers, implications on clinical management, current limitations and future developments in both early- and advanced-stage breast cancer.

A Unique Morphological Phenotype in Chemoresistant Triple-Negative Breast Cancer Reveals Metabolic Reprogramming and PLIN4 Expression as a Molecular Vulnerability

The major obstacle in successfully treating triple-negative breast cancer (TNBC) is resistance to cytotoxic chemotherapy, the mainstay of treatment in this disease. Previous preclinical models of chemoresistance in TNBC have suffered from a lack of clinical relevance. Using a single high dose chemotherapy treatment, we developed a novel MDA-MB-436 cell-based model of chemoresistance characterized by a unique and complex morphologic phenotype, which consists of polyploid giant cancer cells giving rise to neuron-like mononuclear daughter cells filled with smaller but functional mitochondria and numerous lipid droplets. This resistant phenotype is associated with metabolic reprogramming with a shift to a greater dependence on fatty acids and oxidative phosphorylation. We validated both the molecular and histologic features of this model in a clinical cohort of primary chemoresistant TNBCs and identified several metabolic vulnerabilities including a dependence on PLIN4, a perilipin coating the observed lipid droplets, expressed both in the TNBC-resistant cells and clinical chemoresistant tumors treated with neoadjuvant doxorubicin-based chemotherapy. These findings thus reveal a novel mechanism of chemotherapy resistance that has therapeutic implications in the treatment of drug-resistant cancer. IMPLICATIONS: These findings underlie the importance of a novel morphologic-metabolic phenotype associated with chemotherapy resistance in TNBC, and bring to light novel therapeutic targets resulting from vulnerabilities in this phenotype, including the expression of PLIN4 essential for stabilizing lipid droplets in resistant cells.

Systematic review of basket trials, umbrella trials, and platform trials: a landscape analysis of master protocols

BACKGROUND

Master protocols, classified as basket trials, umbrella trials, and platform trials, are novel designs that investigate multiple hypotheses through concurrent sub-studies (e.g., multiple treatments or populations or that allow adding/removing arms during the trial), offering enhanced efficiency and a more ethical approach to trial evaluation. Despite the many advantages of these designs, they are infrequently used.

METHODS

We conducted a landscape analysis of master protocols using a systematic literature search to determine what trials have been conducted and proposed for an overall goal of improving the literacy in this emerging concept. On July 8, 2019, English-language studies were identified from MEDLINE, EMBASE, and CENTRAL databases and hand searches of published reviews and registries.

RESULTS

We identified 83 master protocols (49 basket, 18 umbrella, and 16 platform trials). The number of master protocols has increased rapidly over the last five years. Most have been conducted in the US (n = 44/83) and investigated experimental drugs (n = 82/83) in the field of oncology (n = 76/83). The majority of basket trials were exploratory (i.e., phase I/II; n = 47/49) and not randomized (n = 44/49), and more than half (n = 28/48) investigated only a single intervention. The median sample size of basket trials was 205 participants (interquartile range, Q3-Q1 [IQR]: 500-90 = 410), and the median study duration was 22.3 (IQR: 74.1-42.9 = 31.1) months. Similar to basket trials, most umbrella trials were exploratory (n = 16/18), but the use of randomization was more common (n = 8/18). The median sample size of umbrella trials was 346 participants (IQR: 565-252 = 313), and the median study duration was 60.9 (IQR: 81.3-46.9 = 34.4) months. The median number of interventions investigated in umbrella trials was 5 (IQR: 6-4 = 2). The majority of platform trials were randomized (n = 15/16), and phase III investigation (n = 7/15; one did not report information on phase) was more common in platform trials with four of them using seamless II/III design. The median sample size was 892 (IQR: 1835-255 = 1580), and the median study duration was 58.9 (IQR: 101.3-36.9 = 64.4) months.

CONCLUSIONS

We anticipate that the number of master protocols will continue to increase at a rapid pace over the upcoming decades. More efforts to improve awareness and training are needed to apply these innovative trial design methods to fields outside of oncology.

Advances in Targeted Therapies for Triple-Negative Breast Cancer

While the outcomes for patients diagnosed with hormone receptor positive (HR+) and/or human epidermal growth factor receptor 2-positive (HER2+) breast cancers have continued to improve with the development of targeted therapies, the same cannot be said yet for those affected with triple-negative breast cancer (TNBC). Currently, the mainstay of treatment for the 10-15% of patients diagnosed with TNBC remains cytotoxic chemotherapy, but it is hoped that through an enhanced characterization of TNBC biology, this disease will be molecularly delineated into subgroups with targetable oncogenic drivers. This review will focus on recent therapeutic innovations for TNBC, including poly-ADP-ribosyl polymerase (PARP) inhibitors, phosphoinositide 3-kinase (PI3K) pathway inhibitors, immune checkpoint inhibitors, and cyclin-dependent kinase (CDK) inhibitors.

Reporting of master protocols towards a standardized approach: A systematic review

BACKGROUND

In September 2018 the FDA provided a draft guidance on master protocols reflecting an increased interest in these designs by industry. Master protocols refer to a single overarching protocol developed to evaluate multiple hypotheses and may be further categorized as basket, umbrella, and platform trials. However, inconsistencies in reporting persist in the literature. We conducted a systematic review to describe master protocol reporting with the goal of facilitating the further development and spread of these innovative trial designs.

METHODS

We searched MEDLINE, EMBASE, and CENTRAL from inception to April 25, 2019 for English articles on master protocols. This was supplemented by hand searches of trial registries and of the bibliographies of published reviews. We used the FDA's definitions of master protocols as references and compared them to self-reported master protocols.

RESULTS

We identified 278 master protocol publications, consisting of 228 protocols and 50 reviews. Sixty-six records provided unique definitions of master protocol types. We observed considerable heterogeneity in definitions of master protocols, and over half (54%) used oncology-specific language. The majority of self-classified master protocols (57%) were consistent with the FDA's definitions of master protocols.

CONCLUSION

The terms 'master protocol', 'basket trial', 'umbrella trial', and 'platform trial' are inconsistently described. Careful treatment of these terms and adherence to the definitions set forth by the FDA will facilitate better understanding of these trial designs and allow them to be used broadly and to their full potential in clinical research. We encourage trial methodologists to use these trial designations when applicable.

Neoadjuvant Talazoparib for Patients With Operable Breast Cancer With a Germline BRCA Pathogenic Variant

PURPOSE

Talazoparib has demonstrated efficacy in patients with BRCA-positive metastatic breast cancer. This study evaluated the pathologic response of talazoparib alone for 6 months in patients with a known germline BRCA pathogenic variant (gBRCA-positive) and operable breast cancer.

METHODS

Eligibility included 1 cm or larger invasive tumor and gBRCA-positive disease. Human epidermal growth factor receptor 2-positive tumors were excluded. Twenty patients underwent a pretreatment biopsy, 6 months of once per day oral talazoparib (1 mg), followed by definitive surgery. Patients received adjuvant therapy at physician's discretion. The primary end point was residual cancer burden (RCB). With 20 patients, the RCB-0 plus RCB-I response rate can be estimated with a 95% CI with half width less than 20%.

RESULTS

Twenty patients were enrolled from August 2016 to September 2017. Median age was 38 years (range, 23 to 58 years); 16 patients were gBRCA1 positive and 4 patients were gBRCA2 positive. Fifteen patients had triple-negative breast cancer (estrogen receptor/progesterone receptor < 10%), and five had hormone receptor-positive disease. Five patients had clinical stage I disease, 12 had stage II, and three had stage III, including one patient with inflammatory breast carcinoma and one with metaplastic chondrosarcomatous carcinoma. One patient chose to receive chemotherapy before surgery and was not included in RCB analyses. RCB-0 (pathologic complete response) rate was 53% and RCB-0/I was 63%. Eight patients (40%) had grade 3 anemia and required a transfusion, three patients had grade 3 neutropenia, and 1 patient had grade 4 thrombocytopenia. Common grade 1 or 2 toxicities were nausea, fatigue, neutropenia, alopecia, dizziness, and dyspnea. Toxicities were managed by dose reduction and transfusions. Nine patients required dose reduction.

CONCLUSION

Neoadjuvant single-agent oral talazoparib once per day for 6 months without chemotherapy produced substantial RCB-0 rate with manageable toxicity. The substantive pathologic response to single-agent talazoparib supports the larger, ongoing neoadjuvant trial (ClinicalTrials.gov identifier: NCT03499353).

Bayesian clinical trials at The University of Texas MD Anderson Cancer Center: An update

BACKGROUND/AIMS

In our 2009 article, we showed that Bayesian methods had established a foothold in developing therapies in our institutional oncology trials. In this article, we will document what has happened since that time. In addition, we will describe barriers to implementing Bayesian clinical trials, as well as our experience overcoming them.

METHODS

We reviewed MD Anderson Cancer Center clinical trials submitted to the institutional protocol office for scientific and ethical review between January 2009 and December 2013, the same length time period as the previous article. We tabulated Bayesian methods implemented for design or analyses for each trial and then compared these to our previous findings.

RESULTS

Overall, we identified 1020 trials and found that 283 (28%) had Bayesian components so we designated them as Bayesian trials. Among MD Anderson-only and multicenter trials, 56% and 14%, respectively, were Bayesian, higher rates than our previous study. Bayesian trials were more common in phase I/II trials (34%) than in phase III/IV (6%) trials. Among Bayesian trials, the most commonly used features were for toxicity monitoring (65%), efficacy monitoring (36%), and dose finding (22%). The majority (86%) of Bayesian trials used non-informative priors. A total of 75 (27%) trials applied Bayesian methods for trial design and primary endpoint analysis. Among this latter group, the most commonly used methods were the Bayesian logistic regression model (N = 22), the continual reassessment method (N = 20), and adaptive randomization (N = 16). Median institutional review board approval time from protocol submission was the same 1.4 months for Bayesian and non-Bayesian trials. Since the previous publication, the Biomarker-Integrated Approaches of Targeted Therapy for Lung Cancer Elimination (BATTLE) trial was the first large-scale decision trial combining multiple treatments in a single trial. Since then, two regimens in breast cancer therapy have been identified and published from the cooperative Investigation of Serial Studies to Predict Your Therapeutic Response with Imaging and Molecular Analysis (I-SPY 2), enhancing cooperation among investigators and drug developers across the nation, as well as advancing information needed for personalized medicine. Many software programs and Shiny applications for Bayesian trial design and calculations are available from our website which has had more than 21,000 downloads worldwide since 2004.

CONCLUSION

Bayesian trials have the increased flexibility in trial design needed for personalized medicine, resulting in more cooperation among researchers working to fight against cancer. Some disadvantages of Bayesian trials remain, but new methods and software are available to improve their function and incorporation into cancer clinical research.

Efficacy and safety of neoadjuvant chemotherapy regimens for triple-negative breast cancer: a network meta-analysis

Different neoadjuvant chemotherapies are available for triple-negative breast cancer (TNBC). Here, we performed a network meta-analysis to evaluate the pathological complete response (pCR) benefit and safety of treatment regimens. Pairwise and Bayesian network meta-analyses were performed to compare direct and indirect evidence, respectively. Twenty-three studies involving 12 regimens namely standard chemotherapeutic agents, bevacizumab (B)-, platinum salts (P)-, B plus P (BP)-, poly(ADP-ribose) polymerase inhibitors (Pi)-, P plus Pi (PPi)-, capecitabine (Ca)-, gemcitabine (Ge)-, zoledronic acid (Za)-, everolimus (E)-, P plus E (PE)-, and gefitinib (G)-containing regimens. The results showed that P-, B-, PPi-, and Za-containing regimens achieved higher pCR than standard chemotherapeutic agents. BP-containing regimens had a better pCR than B-containing regimens. In indirect comparisons, Za-, BP-, P-, and B-containing regimens were the top four strategies with the highest probability for pCR. Benefit-risk analysis showed that B-containing regimens had the highest acceptability of being the best treatment for better pCR achievement with fewer SAEs. The addition of P, B, BP, PPi, and Za to standard chemotherapeutic agents enhanced the pCR, but a balance between efficacy and safety should be carefully considered. B-containing regimens might be the best choice for neoadjuvant chemotherapy due to its better efficacy and tolerability.

A meta-analysis of platinum-based neoadjuvant chemotherapy versus standard neoadjuvant chemotherapy for triple-negative breast cancer

Aim: Platinum agents are DNA damaging agents with promising activity in breast cancers, especially in triple-negative subgroup. This meta-analysis was conducted to compare the treatments of platinum-based neoadjuvant chemotherapy (NAC) and standard NAC for triple-negative breast cancers (TNBCs). Materials & methods: Diverse electronic databases were searched to identify the randomized clinical trials that directly compared the treatments of platinum-based NAC versus NAC in TNBC patients. Toxicity of platinum-based regimens was further evaluated. Results: Addition of platinum agents significantly improved the pathological complete response rates in TNBC patients compared with the standard NAC. Unfortunately, platinum-based regimens were more likely to develop higher incidence of hematologic toxicities. Conclusion: Platinum-based NAC regimens could achieve significant pathological complete response improvement with well-tolerated toxicity in TNBC patients.

Interim analysis of a real-world precision medicine platform for molecular profiling of metastatic or advanced cancers: MONDTI

Background

High-throughput genomic profiling of tumour specimens facilitates the identification of individual actionable mutations which could be used for individualised targeted therapy. This approach is becoming increasingly more common in the clinic; however, the interpretation of results from molecular profiling tests and efficient guiding of molecular therapies to patients with advanced cancer offer a significant challenge to the oncology community.

Experimental design

MONDTI is a precision medicine platform for molecular characterisation of metastatic solid tumours to identify actionable genomic alterations. From 2013 to 2016, comprehensive molecular profiles derived from real-time biopsy specimens and archived tumour tissue samples of 295 patients were performed. Results and treatment suggestions were discussed within multidisciplinary tumour board meetings.

Results

The mutational profile was obtained from 293 (99%) patients and a complete immunohistochemical (IHC) and cytogenetic profile was obtained in 181 (61%) and 188 (64%) patients. The most frequent cancer types were colorectal cancer (12%), non-Hodgkin's lymphomas (9.8%) and head and neck cancers (7.8%). The most commonly detected mutations were TP53 (39%), KRAS (19%) and PIK3CA (9.5%), whereas ≥1 mutation were identified in 217 (74%) samples. Regarding the results for IHC testing, samples were positive for phospho-mammalian target of rapamycin (phospho-mTOR) (71%), epidermal growth factor receptor (EGFR) (68%), mesenchymal epithelial transition (MET) (56%) and/or platelet-derived growth factor alpha (PDGFRα)-expression (48%). Of the 288 tumour samples with one or more genetic alteration detected, 160 (55.6%) targeted therapy recommendations through 67 multidisciplinary tumour board meetings were made; in 69 (24%) cases, an individual treatment concept was initiated.

Conclusions

The results reveal that the open concept for all solid tumours characterised for molecular profile and immunotherapy could not only match individualised treatment concepts at a high rate but also underscores the challenges encountered when offering molecularly matched therapies to a patient population with an advanced stage cancer.

Olaparib in germline-mutated metastatic breast cancer: implications of the OlympiAD trial

Breast cancer remains a leading cause of death worldwide. Our increased understanding of cellular mechanisms inherent to cancer has led to the development of new therapeutic targets. One such therapy is that of poly(ADP-ribose) polymerase (PARP) inhibitors, with PARP playing a key role in the repair of single stranded DNA breaks. The development of drugs able to inhibit PARP led to their investigation in tumors that have defective DNA repair, including that of BRCA1/2-associated cancers. The PARP inhibitor Olaparib, has recently been evaluated in the Phase III OlympiAD trial, and demonstrated a significant progression-free survival advantage in patients with HER2-negative metastatic breast cancer and a germline BRCA-mutation. This article will review the findings and potential implications of the trial.

Progress in adjuvant systemic therapy for breast cancer

The prognosis of patients with early stage breast cancer has greatly improved in the past three decades. Following the first adjuvant endocrine therapy and chemotherapy trials, continuous improvements of clinical outcomes have been achieved through intense therapeutic escalation, albeit with increased health-care costs and treatment-related toxicities. In contrast to the advances achieved in surgery or radiotherapy, the identification of the patient subgroups that will derive clinical benefit from therapeutic escalation has proved to be a daunting process hindered by a lack of collaboration between scientific groups and by the pace of drug development. In the past few decades, initiatives towards de-escalation of systemic adjuvant treatment have achieved success. Herein, we summarize attempts to escalate and de-escalate adjuvant systemic treatment for patients with breast cancer and argue that new, creative trial designs focused on patients' actual needs rather than on maximizing drug market size are needed. Ultimately, the adoption of effective treatments that do not needlessly expose patients and health-care systems to harm demands extensive international collaboration between academic groups, governments, and pharmaceutical companies.

PARP Inhibitors in the Treatment of Triple-Negative Breast Cancer

Breast cancer is a heterogeneous disease, manifesting in a broad differentiation in phenotypes and morphologic profiles, resulting in variable clinical behavior. Between 10 and 20% of all breast cancers are triple negative. Triple-negative breast cancer (TNBC) lacks the expression of human epidermal growth factor receptor 2 (HER2) and hormone receptors; therefore, to date, chemotherapy remains the backbone of treatment. TNBC tends to be aggressive and has a high histological grade, resulting in a poor 5-year prognosis. It has a high prevalence of BRCA1 mutations and an increased Ki-67 expression. This subtype usually responds well to taxanes and/or platinum compounds and poly (ADP-ribose) polymerase (PARP) inhibitors. Studies with PARP inhibitors have demonstrated promising results in the treatment of BRCA-mutated breast and ovarian cancer, and PARP inhibitors have been studied as monotherapy and in combination with cytotoxic therapy or radiotherapy. PARP inhibitor efficacy on poly (ADP-ribose) polymer (PAR) formation in vivo can be quantified by pharmacodynamic assays that measure PAR activity in peripheral blood mononuclear cells (PBMC). Biomarkers such as TP53, ATM, PALB2 and RAD51C might be prognostic or predictive indicators for treatment response, and could also provide targets for novel treatment strategies. In summary, this review provides an overview of the treatment options for basal-like TNBC, including PARP inhibitors, and focuses on the pharmacotherapeutic options in these patients.

Exploiting DNA repair defects in breast cancer: from chemotherapy to immunotherapy

Introduction: Impaired DNA damage response (DDR) and subsequent genomic instability are associated with the carcinogenic process itself, but it also results in sensitivity of tumor cells to certain drugs and can be exploited to treat cancer by inducing deadly mutations or mitotic catastrophe. Exploiting DDR defects in breast cancer cells has been one of the main strategies in both conventional chemotherapy, targeted therapies, or immunotherapies. Areas covered: In this review, the authors first discuss DDR mechanisms in healthy cells and DDR defects in breast cancer, then focus on current therapies and developments in the treatment of DDR-deficient breast cancer. Expert opinion: Among conventional chemotherapeutics, platinum-based regimens, in particular, seem to be effective in DDR-deficient patients. PARP inhibitors represent one of the successful models of translational research in this area and clinical data showed high efficacy and reasonable toxicity with these agents in patients with breast cancer and BRCA mutation. Recent studies have underlined that some subtypes of breast cancer are highly immunogenic. Promising activity has been shown with immunotherapeutic agents, particularly in DDR-deficient breast cancers. Chemotherapeutics, DNA-repair pathway inhibitors, and immunotherapies might result in further improved outcomes in certain subsets of patients with breast cancer and DDR.

A case report of vanishing bile duct syndrome after exposure to pexidartinib (PLX3397) and paclitaxel

Pexidartinib (PLX3397) is a small molecule tyrosine kinase and colony-stimulating factor-1 inhibitor with FDA breakthrough therapy designation for tenosynovial giant-cell tumor, and currently under study in several other tumor types, including breast cancer, non-Hodgkin's lymphoma, and glioblastoma. Here, we report a case of severe drug-induced liver injury requiring liver transplantation due to vanishing bile duct syndrome (VBDS) after exposure to pexidartinib in the I-SPY 2 Trial, a phase 2 multicenter randomized neoadjuvant chemotherapy trial in patients with Stage II-III breast cancer. We also review the current literature on this rare, idiosyncratic, and potentially life-threatening entity.

Rethinking the Gold Standard With Multi-armed Bandits: Machine Learning Allocation Algorithms for Experiments

In experiments, researchers commonly allocate subjects randomly and equally to the different treatment conditions before the experiment starts. While this approach is intuitive, it means that new information gathered during the experiment is not utilized until after the experiment has ended. Based on methodological approaches from other scientific disciplines such as computer science and medicine, we suggest machine learning algorithms for subject allocation in experiments. Specifically, we discuss a Bayesian multi-armed bandit algorithm for randomized controlled trials and use Monte Carlo simulations to compare its efficiency with randomized controlled trials that have a fixed and balanced subject allocation. Our findings indicate that a randomized allocation based on Bayesian multi-armed bandits is more efficient and ethical in most settings. We develop recommendations for researchers and discuss the limitations of our approach.

Therapeutic innovations in breast cancer

Managing endocrine resistance and resistance to endocrine therapy for ER+ HER2- breast cancer with the CDK 4/6 inhibitors in the metastatic setting. New antibodies drug conjugates for HER2+ and TNBC. Targeting DNA damage and synthetic lethality strategies with PARP inhibitors for breast cancer patients harboring BRCA mutation. Immunotherapies in 1st line metastatic setting of TNBC.

A novel UCHL3 inhibitor, perifosine, enhances PARP inhibitor cytotoxicity through inhibition of homologous recombination-mediated DNA double strand break repair

Triple-negative breast cancer (TNBC) treatment remains a great challenge for clinical practice and novel therapeutic strategies are urgently needed. UCHL3 is a deubiquitinase that is overexpressed in TNBC and correlates with poor prognosis. UCHL3 deubiquitinates RAD51 thereby promoting the recruitment of RAD51 to DNA damage sites and augmenting DNA repair. Therefore, UCHL3 overexpression can render cancer cells resistant to DNA damage inducing chemo and radiotherapy, and targeting UCHL3 can sensitize TNBC to radiation and chemotherapy. However, small molecule inhibitors of UCHL3 are yet to be identified. Here we report that perifosine, a previously reported Akt inhibitor, can inhibit UCHL3 in vitro and in vivo. We found low dose (50 nM) perifosine inhibited UCHL3 deubiquitination activity without affecting Akt activity. Furthermore, perifosine enhanced Olaparib-induced growth inhibition in TNBC cells. Mechanistically, perifosine induced RAD51 ubiquitination and blocked the RAD51-BRCA2 interaction, which in turn decreased ionizing radiation-induced foci (IRIF) of Rad51 and, thereby, homologous recombination (HR)-mediated DNA double strand break repair. In addition, combination of perifosine and Olaparib showed synergistic antitumor activity in vivo in TNBC xenograft model. Thus, our present study provides a novel therapeutic approach to optimize PARP inhibitor treatment efficiency.

Moving From Poly (ADP-Ribose) Polymerase Inhibition to Targeting DNA Repair and DNA Damage Response in Cancer Therapy

The DNA damage response (DDR) pathway coordinates the identification, signaling, and repair of DNA damage caused by endogenous or exogenous factors and regulates cell-cycle progression with DNA repair to minimize DNA damage being permanently passed through cell division. Severe DNA damage that cannot be repaired may trigger apoptosis; as such, the DDR pathway is of crucial importance as a cancer target. Poly (ADP-ribose) polymerase (PARP) is the best-known element of the DDR, and several PARP inhibitors have been licensed. However, there are approximately 450 proteins involved in DDR, and a number of these other targets are being investigated in the laboratory and clinic. We review the most recent evidence for the clinical effect of PARP inhibition in breast and ovarian cancer and explore expansion into the first-line setting and into other tumor types. We critique the evidence for patient selection techniques and summarize what is known about mechanisms of PARP inhibitor resistance. We then discuss what is known about the preclinical rationale for targeting other members of the DDR pathway and the associated tumor cell genetics that may confer sensitivity to these agents. Examples include DNA damage sensors (MLH1), damage signaling molecules (ataxia-telangiectasia mutated; ataxia-telangiectasia mutated-related and Rad3-related; CHK1/2; DNA-dependent protein kinase, catalytic subunit; WEE1; CDC7), or effector proteins for repair (POLQ [also referred to as POLθ], RAD51, poly [ADP-ribose] glycohydrolase). Early-phase clinical trials targeting some of these molecules, either as a single agent or in combination, are discussed. Finally, we outline the challenges that must be addressed to maximize the therapeutic opportunity that targeting DDR provides.

Advances in the use of PARP inhibitors for BRCA1/2-associated breast cancer: talazoparib

Poly-ADP-ribosyl polymerase (PARP) enzymes PARP-1 and PARP-2 recognize DNA damage and set off a cascade of cellular mechanisms required for multiple types of DNA damage repair. PARP inhibitors are small molecule mimetics of nicotinamide which bind to PARP’s catalytic domain to inhibit poly-ADP-ribosylation (PARylation) of target proteins, including PARP-1 itself. PARP inhibitors olaparib, veliparib, talazoparib, niraparib and rucaparib have predominantly been studied in women with breast or ovarian cancers associated with deleterious germline mutations in BRCA1 and BRCA2 (gBRCA1/2+). The BRCA1 and BRCA2 proteins are involved in DNA repair by homologous recombination. This review will focus on talazoparib, a PARP inhibitor approved by the US FDA for the treatment of metastatic gBRCA1/2+ breast cancers in October 2018.

Additive value of diffusion-weighted MRI in the I-SPY 2 TRIAL

BACKGROUND

The change in apparent diffusion coefficient (ADC) measured from diffusion-weighted imaging (DWI) has been shown to be predictive of pathologic complete response (pCR) for patients with locally invasive breast cancer undergoing neoadjuvant chemotherapy.

PURPOSE

To investigate the additive value of tumor ADC in a multicenter clinical trial setting.

STUDY TYPE

Retrospective analysis of multicenter prospective data.

POPULATION

In all, 415 patients who enrolled in the I-SPY 2 TRIAL from 2010 to 2014 were included.

FIELD STRENGTH/SEQUENCE

1.5T or 3T MRI system using a fat-suppressed single-shot echo planar imaging sequence with b-values of 0 and 800 s/mm2 for DWI, followed by a T1-weighted sequence for dynamic contrast-enhanced MRI (DCE-MRI) performed at pre-NAC (T0), after 3 weeks of NAC (T1), mid-NAC (T2), and post-NAC (T3).

ASSESSMENT

Functional tumor volume and tumor ADC were measured at each MRI exam; pCR measured at surgery was assessed as the binary outcome. Breast cancer subtype was defined by hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status.

STATISTICAL TESTS

A logistic regression model was used to evaluate associations between MRI predictors with pCR. The cross-validated area under the curve (AUC) was calculated to assess the predictive performance of the model with and without ADC.

RESULTS

In all, 354 patients (128 HR+/HER2-, 60 HR+/HER2+, 34 HR-/HER2+, 132 HR-/HER2-) were included in the analysis. In the full cohort, adding ADC predictors increased the AUC from 0.76 to 0.78 at mid-NAC and from 0.76 to 0.81 at post-NAC. In HR/HER2 subtypes, the AUC increased from 0.52 to 0.65 at pre-NAC for HR+/HER2-, from 0.67 to 0.73 at mid-NAC and from 0.72 to 0.76 at post-NAC for HR+/HER2+, from 0.71 to 0.81 at post-NAC for triple negatives.

DATA CONCLUSION

The addition of ADC to standard functional tumor volume MRI showed improvement in the prediction of treatment response in HR+ and triple-negative breast cancer.

LEVEL OF EVIDENCE

2 Technical Efficacy Stage: 4 J. Magn. Reson. Imaging 2019;50:1742-1753.

Adaptive and platform trials in remote damage control resuscitation

The traditional approach to clinical trial design requires assuming precise values for multiple unknown parameters, resulting in a trial design that is unlikely to perform well if one or more of those assumptions turn out to be incorrect. During conduct of the trial, trial characteristics are often held fixed, even if incoming data suggest that one or more design assumptions were incorrect. This leads to an increased risk of a failed trial. In contrast, an adaptive clinical trial is designed to take advantage of partial, incoming data during the conduct of the trial, modifying key clinical trial characteristics according to prespecified rules, in order to avoid a failed or inconclusive trial, improve statistical efficacy, better treat patients within the trial, or achieve other scientific or ethical goals. The concept of an adaptive trial can be expanded to a platform trial, a clinical trial that is intended to evaluate multiple treatments or combinations of treatments, often for patients with any of a group of related diseases, and to continue beyond the evaluation of any particular treatment. Platform trial design strategies can be applied to the problem of finding the best treatment strategy for patients suffering from posttraumatic hemorrhagic shock. We present the rationale and considerations surrounding adaptive and platform trial design and apply these concepts to the problem of investigating strategies for remote damage control resuscitation.

Circulating tumor DNA dynamics using patient-customized assays are associated with outcome in neoadjuvantly treated breast cancer

Pathological complete response (pCR) is an accurate predictor of good outcome following neoadjuvant chemotherapy (NAC) for locally advanced breast cancer. The presence of circulating-tumor DNA (ctDNA) has recently been reported to be strongly predictive of poor outcome in similar patient groups. We monitored ctDNA levels from 10 women undergoing NAC for locally advanced breast cancer using a patient-specific, hybrid-capture sequencing technique sensitive to the level of one altered allele in 10,000. Plasma was collected prior to the start of NAC, prior to each infusion of NAC, and during follow-up for between 350 and 1150 d after the start of NAC. Prior to the start of NAC, ctDNA was detectable in 3/3 triple negative, 3/3 HER2⁺, and 2/4 HER2⁻, ER⁺ breast cancer patients. Total cell-free DNA levels were considerably higher when patients were on NAC than at other times. ctDNA dynamics during NAC showed that patients with pCR experienced rapid declines in ctDNA levels, whereas patients without pCR typically showed evidence of residual ctDNA after initiation of treatment. Intriguingly, two of three patients that showed marked increases in ctDNA while on NAC experienced rapid recurrences (<2 yr following start of NAC). The third patient that had increases in ctDNA levels while on NAC had low-grade ER⁺ disease and showed residual ctDNA after surgery, which became undetectable after local radiation. Taken together, these results demonstrate the ability of our approach to sensitively serially monitor ctDNA during NAC, and identifies a need to further investigate the possibility of stratifying patients who need additional treatment or identify therapies that are ineffective.

ATM-dependent activation of SIM2s regulates homologous recombination and epithelial-mesenchymal transition

There is increasing evidence that genomic instability is a prerequisite for cancer progression. Here we show that SIM2s, a member of the bHLH/PAS family of transcription factors, regulates DNA damage repair through enhancement of homologous recombination (HR), and prevents epithelial-mesenchymal transitions (EMT) in an Ataxia-telangiectasia mutated (ATM)-dependent manner. Mechanistically, we found that SIM2s interacts with ATM and is stabilized through ATM-dependent phosphorylation in response to IR. Once stabilized, SIM2s interacts with BRCA1 and supports RAD51 recruitment to the site of DNA damage. Loss of SIM2s through the introduction of shSIM2 or the mutation of SIM2s at one of the predicted ATM phosphorylation sites (S115) reduces HR efficiency through disruption of RAD51 recruitment, resulting in genomic instability and induction of EMT. The EMT induced by the mutation of S115 is characterized by a decrease in E-cadherin and an induction of the basal marker, K14, resulting in increased invasion and metastasis. Together, these results identify a novel player in the DNA damage repair pathway and provides a link in ductal carcinoma in situ progression to invasive ductal carcinoma through loss of SIM2s, increased genomic instability, EMT, and metastasis.

Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT): A Bayesian Adaptive Platform Trial to Develop Precision Medicines for Patients With Glioblastoma

PURPOSE

Adequately prioritizing the numerous therapies and biomarkers available in late-stage testing for patients with glioblastoma (GBM) requires an efficient clinical testing platform. We developed and implemented INSIGhT (Individualized Screening Trial of Innovative Glioblastoma Therapy) as a novel adaptive platform trial (APT) to develop precision medicine approaches in GBM.

METHODS

INSIGhT compares experimental arms with a common control of standard concurrent temozolomide and radiation therapy followed by adjuvant temozolomide. The primary end point is overall survival. Patients with newly diagnosed unmethylated GBM who are IDH R132H mutation negative and with genomic data available for biomarker grouping are eligible. At the initiation of INSIGhT, three experimental arms (neratinib, abemaciclib, and CC-115), each with a proposed genomic biomarker, are tested simultaneously. Initial randomization is equal across arms. As the trial progresses, randomization probabilities adapt on the basis of accumulating results using Bayesian estimation of the biomarker-specific probability of treatment impact on progression-free survival. Treatment arms may drop because of low probability of treatment impact on overall survival, and new arms may be added. Detailed information on the statistical model and randomization algorithm is provided to stimulate discussion on trial design choices more generally and provide an example for other investigators developing APTs.

CONCLUSION

INSIGhT (NCT02977780) is an ongoing novel biomarker-based, Bayesian APT for patients with newly diagnosed unmethylated GBM. Our goal is to dramatically shorten trial execution timelines while increasing scientific power of results and biomarker discovery using adaptive randomization. We anticipate that trial execution efficiency will also be improved by using the APT format, which allows for the collaborative addition of new experimental arms while retaining the overall trial structure.

Analysis of status and countermeasures of cancer incidence and mortality in China

Cancer is the leading cause of human deaths in the world and produces serious economic burdens. On September 12, 2018, the academic journal A Cancer Journal for Clinicians published an article about the latest statistics of cancers worldwide, which provided a status report on the global burden of 36 cancers in 185 countries worldwide. Cancer has also become a serious public health problem in China and caused more and more attention of the government and people in recent years. This review analyzes the incidence, mortality and prevalent trend of cancers in China, discusses the reasons behind this status, and reviews the potential countermeasures for cancer prevention and control in China.

Prospect for Application of PARP Inhibitor in Patients with HER2 Negative Breast Cancer

Human epidermal growth factor receptor (HER2) negative metastatic breast cancer (BC) accounts for 73% of BC. The molecular analysis of this disease is essential for potential options for targeted therapy. Several promising clinical strategies are being evaluated which includes endocrine therapy, modified chemotherapy, angiogenesis inhibitors, immune checkpoint inhibitors, and anti-androgens. New therapeutic approaches are being developed that target BC patients with germline mutations in either BRCA1, BRCA2 as well as BRCAness, a condition in which tumors have molecular similarity to BRCA-mutated tumors. Poly (ADP-ribose) polymerase inhibitors (PARPi) which are effective therapy in germline BRCA1 and BRCA2 mutations, are also observed to be effective in somatic mutations. Germline mutations in the homologous recombination pathway genes could also contribute to PARPi sensitivity. PARPi act as chemo- and radio-sensitizers by limiting the DNA-damage response and potentiating the activity of chemo- and radio-therapy when used alone or in combination with chemotherapy. Apart from PARPi as monotherapy, additional researches are ongoing in combination with cytotoxic chemotherapeutics and targeted agents in HER2 negative BC. This review aims at the most recent developments in the targeted therapy, summarizes the recent clinical trials outcomes, along with the overview of ongoing clinical trials in HER2 negative patients with BRCA1/2 mutations and sporadic tumors with BRCAness.

State-of-the-art strategies for targeting the DNA damage response in cancer

Genomic instability is a key hallmark of cancer that arises owing to defects in the DNA damage response (DDR) and/or increased replication stress. These alterations promote the clonal evolution of cancer cells via the accumulation of driver aberrations, including gene copy-number changes, rearrangements and mutations; however, these same defects also create vulnerabilities that are relatively specific to cancer cells, which could potentially be exploited to increase the therapeutic index of anticancer treatments and thereby improve patient outcomes. The discovery that BRCA-mutant cancer cells are exquisitely sensitive to inhibition of poly(ADP-ribose) polymerase has ushered in a new era of research on biomarker-driven synthetic lethal treatment strategies for different cancers. The therapeutic landscape of antitumour agents targeting the DDR has rapidly expanded to include inhibitors of other key mediators of DNA repair and replication, such as ATM, ATR, CHK1 and CHK2, DNA-PK and WEE1. Efforts to optimize these therapies are ongoing across a range of cancers, involving the development of predictive biomarker assays of responsiveness (beyond BRCA mutations), assessment of the mechanisms underlying intrinsic and acquired resistance, and evaluation of rational, tolerable combinations with standard-of-care treatments (such as chemotherapeutics and radiation), novel molecularly targeted agents and immune-checkpoint inhibitors. In this Review, we discuss the current status of anticancer therapies targeting the DDR.

Medicinal chemistry approaches of poly ADP-Ribose polymerase 1 (PARP1) inhibitors as anticancer agents - A recent update

Poly (ADP-ribose) Polymerase1 (PARP1) is a member of 17 membered PARP family having diversified biological functions such as synthetic lethality, DNA repair, apoptosis, necrosis, histone binding etc. It is primarily a chromatin-bound nuclear enzyme that gets activated by DNA damage. It binds to DNA signal- and double-strand breaks, does parylation of target proteins (using NAD⁺ as a substrate) like histones and other DNA repair proteins and modifies them as a part of DNA repair mechanism. Inhibition of PARP1 prevents the DNA repair and leads to cell death. Clinically, PARP1 Inhibitors have shown their potential in treating BRCAm breast and ovarian cancers and trials are going on for the treatment of other solid tumors like pancreatic, prostate, colorectal etc. as a single agent or in combination. There are currently three FDA approved PARP1 inhibitors namely Olaparib, Rucaparib and Niraparib in the market while Veliparib and Talazoparib are in the late stage of clinical development. All these molecules are nonselective PARP1 inhibitors with concurrent inhibition of PARP2 with similar potency. In addition, resistance to marketed PARP1 inhibitors has been reported. Overall, looking at the success rate of PARP1 inhibitors into various solid tumors, there is an urge of a novel and selective PARP1 inhibitors. This review provides an update on various newer heterocyclic PARP1 inhibitors reported in last three years along with their structural design strategies. We classified them into two main chemical classes; NAD analogues and non-NAD analogues and discussed the medicinal chemistry approaches of each class. To understand the structural features required for in-silico designing of next-generation PARP1 inhibitors, we also reported the crucial amino acid interactions of these inhibitors at the target site. Thus, present review provides the insight on recent development on new lead structures as PARP1 inhibitors, their SAR, an overview of in-vitro and in-vivo screening methods, current challenges and opinion on future designing of more selective and safe PARP1 inhibitors.

Synergistic Cytotoxic Effect of Busulfan and the PARP Inhibitor Veliparib in Myeloproliferative Neoplasms

Patients with high-risk myeloproliferative neoplasms (MPNs), and in particular myelofibrosis (MF), can be cured only with allogeneic hematopoietic stem cell transplantation (HSCT). Because MPNs and JAK2^V617F-mutated cells show genomic instability, stalled replication forks, and baseline DNA double-strand breaks, DNA repair inhibition with poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors represents a potential novel therapy. Because the alkylating agent busulfan is integral in conditioning regimens for HSCT and leads to stalled replication forks through DNA strand cross-linking, we hypothesized that PARP inhibition with veliparib in combination with busulfan may lead to synergistic cytotoxicity in MPN cells. We first treated 2 MPN cell lines harboring the JAK2^V617F mutation (SET2 and HEL) with veliparib at increasing concentrations and measured cell proliferation. SET2 and HEL cells were relatively sensitive to veliparib (IC₅₀ of 11.3 μM and 74.2 μM, respectively). We next treated cells with increasing doses of busulfan in combination with 4 μM veliparib and found that the busulfan IC₅₀ decreased from 27 μM to 4 μM in SET2 cells and from 45.1 μM to 28.1 μM in HEL cells. The mean combination index was .55 for SET2 cells and .40 for HEL cells. Combination treatment of SET2 cells caused G2M arrest in 53% of cells, compared with 30% with veliparib alone and 35% with busulfan alone. G2M arrest was associated with activation of the ATR-Chk1 pathway, as shown by an immunofluorescence assay for phosphorylated Chk1 (p-Chk1). We then tested in vivo the effect of combined low doses of busulfan and veliparib in a JAK2^V617F MPN-AML xenotransplant model. Vehicle- and veliparib-treated mice had similar median survival of 39 and 40 days, respectively. Combination treatment increased median survival from 47 days (busulfan alone) to 50 days (P = .02). Finally, we tested the combined effect of busulfan and veliparib on CD34⁺ cells obtained from the bone marrow or peripheral blood of 5 patients with JAK2^V617F-mutated and 2 patients with CALR-mutated MF. MF cells treated with the combination of veliparib and busulfan showed reduced colony formation compared with busulfan alone (87% versus 68%; P = .001). In contrast, treatment of normal CD34⁺ cells with veliparib did not affect colony growth. Here we show that in vivo confirmation that treatment with the PARP-1 inhibitor veliparib and busulfan results in synergistic cytotoxicity in MPN cells. Our data provide the rationale for testing novel pretransplantation conditioning regimens with combinations of PARP-1 inhibition and reduced doses of alkylators, such as busulfan and melphalan, for high-risk MPNs or MPN-derived acute myelogenous leukemia.

Neoadjuvant nano-photothermal therapy used before operation effectively assists in surgery for breast cancer

Nano-photothermal therapy (NPTT) has attracted increasing interest recently due to its high efficiency, excellent selectivity and non-ionizing radiation damage. Despite a tremendous amount of exciting pre-clinical results reported in the past few years, however, the further clinic application of NPTT is still difficult. To combine NPTT with clinical surgery more closely, novel multifunctional optical-magnetic nanosystems have been synthesized and applied for preoperative NPTT to assist in the follow-up surgery, termed "neoadjuvant NPTT". Remarkably, nanoparticles are mainly aggregated in the cytoplasm of tumor cells in vitro and largely accumulated in the tumor in vivo 24 h after injection. Under the guidance of tri-modality imaging, preoperative NPTT could shrink the tumor in a short time and make the boundary between the tumor and surrounding normal tissues clearer, which is conducive to subsequent surgery resection. Furthermore, the 50% survival rate is up to 50 days compared with 35 days for standard surgery, 31 days for PTT alone and 24 days for non-surgery groups. Therefore, NPTT can effectively assist in surgery used before operation. This study provides a new idea for the clinical transformation of NPTT in the future.

Emerging Novel Therapeutics in Triple-Negative Breast Cancer

The mortality from breast cancer has steadily decreased due in part to early detection and advances in therapy. The treatment options for breast cancer vary considerably depending on the histological subtype. There are a number of very effective targeted therapies available for estrogen receptor-positive disease and for human epidermal growth factor receptor 2-positive disease. However, triple-negative breast cancer is a particularly aggressive subtype. This subtype represents an unmet need for improved therapies. TNBC is a heterogenous subtype of breast cancer that is beginning to be refined by its molecular characteristics and clinical response to a targeted therapeutic approach. Here we review the recent advances in the treatment of TNBC with emphasis on the many emerging novel targeted therapies.

A Bayesian network meta-analysis of the efficacy of targeted therapies and chemotherapy for treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous disease with poorer prognosis than other subtypes, yet effective therapies are still not available. We aimed to compare the efficacy of various targeted therapies with chemotherapy (CT) in TNBC patients using a network meta-analysis. A systematic literature search was performed in PubMed, EMBASE, and the Cochrane Library. A total of 27 randomized controlled trials (RCTs), involving 6924 TNBC patients, were included. Olaparib significantly improved PFS (0.43, 0.29-0.64) and ORR (2.57, 1.31-5.09) in comparison with CT. As for bevacizumab + CT, it showed a significant improvement of PFS (0.66, 0.55-0.80) and ORR (2.15, 1.16-4.05) compared with CT + placebo. It was also superior to CT alone in PFS (0.48, 0.35-0.65) and pCR (1.30, 1.13-1.49 for breast and axillary nodes and 1.26, 1.11-1.44 for breast). Other targeted agents like iniparib, sorafenib, cetuximab, and ipatasertib combined with CT showed significant superiority in PFS compared with CT alone, and the HRs were 0.75 (0.62-0.90), 0.44 (0.21-0.91), 0.67 (0.47-0.96), and 0.44 (0.24-0.81), respectively, while some other agents such as sunitinib and cetuximab had the lowest SUCRA in OS, PFS, or ORR without any benefits. In conclusion, our results indicated that the addition of bevacizumab to CT was beneficial for TNBC patients, and olaparib had a great effect in PFS and ORR, especially for those with BRCA mutations. When combined with CT, targeted agents including iniparib, sorafenib, cetuximab, and ipatasertib may have better efficacies for treating TNBC.

Rising rates of bilateral mastectomy with reconstruction following neoadjuvant chemotherapy

Neoadjuvant chemotherapy (NAC) is used to allow more limited breast surgery without compromising local control. We sought to evaluate nationwide surgical trends in patients with operable breast cancer treated with NAC and factors associated with surgical type. We used the National Cancer Database to identify 235,339 women with unilateral T1-3 N0-3 M0 breast cancer diagnosed between 2010 and 2014 and treated with surgery and chemotherapy. Of these, 59,568 patients (25.3%) were treated with NAC. Rates of pathological complete response (pCR) to NAC increased from 33.3% at the start of the study period in 2010 to 46.3% at the end of the period in 2014 (p = 0.02). Rates of breast-conserving surgery (BSC) changed little, from 37.0 to 40.8% (p = 0.22). Although rates of unilateral mastectomy decreased from 43.3 to 34.7% (p = 0.02) and rates of bilateral mastectomy without immediate reconstruction remained similar (11.7-11.5%; p = 0.82), rates of bilateral mastectomy with immediate reconstruction rose from 8.0 to 13.1% (p = 0.02). Patients who were younger, with private/managed care insurance, and diagnosed in more recent years were more likely to achieve pCR; however, these same characteristics were associated with receipt of bilateral mastectomy (vs. BCS). In addition, non-Hispanic white ethnic and higher area education attainment were both associated with bilateral mastectomy. These findings did not differ by age or molecular subtype. Further study of nonclinical factors that influence selection of more extensive surgery despite excellent response to NAC is warranted.

Racial Disparity and Triple-Negative Breast Cancer in African-American Women: A Multifaceted Affair between Obesity, Biology, and Socioeconomic Determinants

Triple negative breast cancer (TNBC) is a molecularly heterogeneous disease whose incidence is disproportionately higher in African American (AA) women compared to European American (EA) women. Earlier onset, more advanced stage at diagnosis, and aggressive tumor phenotype are some of the characteristic features of TNBC in women with African ethnicity in comparison to EA women, denoting one of the most significant examples of racial disparity in oncology. It is still contentious whether health disparities result in aggressive behavior of TNBC in AA women or it is indeed a molecularly distinct disease. Given the “gaps-in-knowledge” surrounding racial disparity in TNBC, this review discusses various socioeconomic factors and the genetic predispositions contributing to poor prognosis of TNBC in AA women. While socioeconomic factors may contribute to poorer survival, multiple preclinical and clinical studies suggest inherent genetic risk factors and aberrant activation of oncogenic pathways in AA TNBC. Additionally, AA women are more likely to be obese and obesity is known to drive a molecular circuitry resulting in aggressive tumor progression indicating a potential obesity-TNBC axis at work in AA women. Given the multifactorial nature of AA TNBC, a transdisciplinary approach may help bridge the disparity that exists between AA and EA TNBC.

Targeting BRCA Deficiency in Breast Cancer: What are the Clinical Evidences and the Next Perspectives?

Breast cancers (BC) associated with germline mutations of BRCA1/2 represent 3–5% of cases. BRCA1/2-associated BC have biological features leading to genomic instability and potential sensitivity to DNA damaging agents, including poly(ADP-ribose) polymerase (PARP) and platinum agents. In this review, we will summarize clinical trials of chemotherapy and PARP inhibitors (PARPi), alone or in combination, at the early or late stage of BRCA1/2-associated BC. We will also present the mechanisms of resistance to PARPi as well as the new therapeutic strategies of association with PARPi. Finally, we will discuss under which conditions the use of DNA damaging agents can be extended to the BRCA1/2-wild type population, the BRCAness concept.

BET proteins regulate homologous recombination-mediated DNA repair: BRCAness and implications for cancer therapy

Bromodomain and Extra-Terminal (BET) proteins are historically involved in regulating gene expression and BRD4 was recently found to be involved in DNA damage regulation. Aims of our study were to assess BRD4 regulation in homologous recombination-mediated DNA repair and to explore novel clinical strategies through the combinations of the pharmacological induction of epigenetic BRCAness in BRCA1 wild-type triple negative breast cancer (TNBC) cells by means of BET inhibitors and compounds already available in clinic. Performing a dual approach (chromatin immunoprecipitation and RNA interference), the direct relationship between BRD4 and BRCA1/RAD51 expression was confirmed in TNBC cells. Moreover, BRD4 pharmacological inhibition using two BET inhibitors (JQ1 and GSK525762A) induced a dose-dependent reduction in BRCA1 and RAD51 levels and is able to hinder homologous recombination-mediated DNA damage repair, generating a BRCAness phenotype in TNBC cells. Furthermore, BET inhibition impaired the ability of TNBC cells to overcome the increase in DNA damage after platinum salts (i.e., CDDP) exposure, leading to massive cell death, and triggered synthetic lethality when combined with PARP inhibitors (i.e., AZD2281). Altogether, the present study confirms that BET proteins directly regulate the homologous recombination pathway and their inhibition induced a BRCAness phenotype in BRCA1 wild-type TNBC cells. Noteworthy, being this strategy based on drugs already available for human use, it is rapidly transferable and could potentially enable clinicians to exploit platinum salts and PARP inhibitors-based treatments in a wider population of TNBC patients and not just in a specific subgroup, after validating clinical trials.

Primary medical therapy and breast conservation treatment: the medical oncology perspective

Primary systemic therapy (PST) is a widely adopted strategy for increasing operability and breast conservation rates. Although first generation PST trials failed to demonstrate improvements in disease free and overall survival compared to adjuvant systemic therapy (AST), they did demonstrate a strong association between attainment of pathologic complete response (pCR) and improved survival outcomes, leading to the widespread adoption of pCR as the primary endpoint in subsequent PST trials. First generation trials also showed that preoperative PST can improve breast conservation rates and downstage the axilla. Although individual trials did not demonstrate statistically significant increase in local recurrence with PST when compared to AST, a recent meta-analysis did note an increased in such risk, mainly driven by trials in which surgery was omitted in patients with good response to PST. Successive generations of PST clinical trials have since explored the activity of taxanes, optimization of anthracycline and taxane dose and schedules, incorporation of single and dual anti-HER2 therapy in HER2 overexpressing breast cancer, the use of platinums in triple negative breast cancer, and the role of endocrine therapy in hormone receptor positive breast cancer. While these PST trials have generally found increased pCR rates with the introduction of modern chemotherapy regimens and targeted therapies, they have not consistently demonstrated further improvements in breast conservation rates compared to first generation regimens. The reasons for this are complex and may lie beyond differences in anti-tumour activity between different systemic regimens but rather in other potential confounding factors such as tumour to breast volume ratio, tumour location, multicentricity as well as patient or surgeon preference.

Pathological Response and Survival in Triple-Negative Breast Cancer Following Neoadjuvant Carboplatin plus Docetaxel

PURPOSE

Prognostic value of pathologic complete response (pCR) and extent of pathologic response attained with anthracycline-free platinum plus taxane neoadjuvant chemotherapy (NAC) in triple-negative breast cancer (TNBC) is unknown. We report recurrence-free survival (RFS) and overall survival (OS) according to degree of pathologic response in patients treated with carboplatin plus docetaxel NAC.

PATIENTS AND METHODS

One-hundred and ninety patients with stage I-III TNBC were treated with neoadjuvant carboplatin (AUC6) plus docetaxel (75 mg/m2) every 21 days × 6 cycles. pCR (no evidence of invasive tumor in breast and axilla) and Residual cancer burden (RCB) were evaluated. Patients were followed for recurrence and survival. Extent of pathologic response was associated with RFS and OS using the Kaplan-Meier method.

RESULTS

Median age was 51 years, and 52% were node-positive. pCR and RCB I rates were 55% and 13%, respectively. Five percent of pCR patients, 0% of RCB I patients, and 58% of RCB II/III patients received adjuvant anthracyclines. Three-year RFS and OS were 79% and 87%, respectively. Three-year RFS was 90% in patients with pCR and 66% in those without pCR [HR = 0.30; 95% confidence interval (CI), 0.14-0.62; P = 0.0001]. Three-year OS was 94% in patients with pCR and 79% in those without pCR (HR = 0.25; 95% CI, 0.10-0.63; P = 0.001). Patients with RCB I demonstrated 3-year RFS (93%) and OS (100%) similar to those with pCR. On multivariable analysis, higher tumor stage, node positivity, and RCB II/III were associated with worse RFS.

CONCLUSIONS

Neoadjuvant carboplatin plus docetaxel yields encouraging efficacy in TNBC. Patients achieving pCR or RCB I with this regimen demonstrate excellent 3-year RFS and OS without adjuvant anthracycline.

Diffusion-weighted MRI Findings Predict Pathologic Response in Neoadjuvant Treatment of Breast Cancer: The ACRIN 6698 Multicenter Trial

Purpose To determine if the change in tumor apparent diffusion coefficient (ADC) at diffusion-weighted (DW) MRI is predictive of pathologic complete response (pCR) to neoadjuvant chemotherapy for breast cancer. Materials and Methods In this prospective multicenter study, 272 consecutive women with breast cancer were enrolled at 10 institutions (from August 2012 to January 2015) and were randomized to treatment with 12 weekly doses of paclitaxel (with or without an experimental agent), followed by 12 weeks of treatment with four cycles of anthracycline. Each woman underwent breast DW MRI before treatment, at early treatment (3 weeks), at midtreatment (12 weeks), and after treatment. Percentage change in tumor ADC from that before treatment (ΔADC) was measured at each time point. Performance for predicting pCR was assessed by using the area under the receiver operating characteristic curve (AUC) for the overall cohort and according to tumor hormone receptor (HR)/human epidermal growth factor receptor 2 (HER2) disease subtype. Results The final analysis included 242 patients with evaluable serial imaging data, with a mean age of 48 years ± 10 (standard deviation); 99 patients had HR-positive (hereafter, HR+)/HER2-negative (hereafter, HER2-) disease, 77 patients had HR-/HER2- disease, 42 patients had HR+/HER2+ disease, and 24 patients had HR-/HER2+ disease. Eighty (33%) of 242 patients experienced pCR. Overall, ΔADC was moderately predictive of pCR at midtreatment/12 weeks (AUC = 0.60; 95% confidence interval [CI]: 0.52, 0.68; P = .017) and after treatment (AUC = 0.61; 95% CI: 0.52, 0.69; P = .013). Across the four disease subtypes, midtreatment ΔADC was predictive only for HR+/HER2- tumors (AUC = 0.76; 95% CI: 0.62, 0.89; P < .001). In a test subset, a model combining tumor subtype and midtreatment ΔADC improved predictive performance (AUC = 0.72; 95% CI: 0.61, 0.83) over ΔADC alone (AUC = 0.57; 95% CI: 0.44, 0.70; P = .032.). Conclusion After 12 weeks of therapy, change in breast tumor apparent diffusion coefficient at MRI predicts complete pathologic response to neoadjuvant chemotherapy. © RSNA, 2018 Online supplemental material is available for this article.