Understanding the promising role of antibody drug conjugates in breast and ovarian cancer

A nascent category of anticancer therapeutic drugs called antibody-drug conjugates (ADCs) relate selectivity of aimed therapy using chemotherapeutic medicines with high cytotoxic power. Progressive linker technology led to the advancement of more efficacious and safer treatments. It offers neoteric as well as encouraging therapeutic strategies for treating cancer. ADCs selectively administer a medication by targeting antigens which are abundantly articulated on the membrane surface of tumor cells. Tumor-specific antigens are differently expressed in breast and ovarian cancers and can be utilized to direct ADCs. Compared to conventional chemotherapeutic drugs, this approach enables optimal tumor targeting while minimizing systemic damage. A cleavable linker improves the ADCs because it allows the toxic payload to be distributed to nearby cells that do not express the target protein, operating on assorted tumors with dissimilar cell aggregation. Presently fifteen ADCs are being studied in breast and ovarian carcinoma preclinically, and assortment of few have already undergone promising early-phase clinical trial testing. Furthermore, Phase I and II studies are investigating a wide variety of ADCs, and preliminary findings are encouraging. An expanding sum of ADCs will probably become feasible therapeutic choices as solo agents or in conjunction with chemotherapeutic agents. This review accentuates the most recent preclinical findings, pharmacodynamics, and upcoming applications of ADCs in breast and ovarian carcinoma.

A risk stratification model to predict chemotherapy benefit in medullary carcinoma of the breast: a population-based SEER database

Whether patients with medullary breast carcinoma (MBC) receive chemotherapy is controversial. Therefore, the aim of our study was to screen out patients with MBC who benefit from chemotherapy. We enrolled 618 consecutive patients with MBC from The Surveillance, Epidemiology, and End Results (SEER) database (2010-2018). Cox regression analysis was used to identify independent prognostic factors. Next, a nomogram was constructed and evaluated using calibration plots and the area under the curve (AUC) of receiver operating characteristic (ROC) curves. Kaplan‒Meier curves were used to evaluate the overall survival (OS) benefit of chemotherapy in different risk groups. A total of 618 MBC patients were involved in our study, and an 8:2 ratio was used to randomly split them into a training cohort (n = 545) and a validation cohort (n = 136). Next, a nomogram predicting 3- and 5-year OS rates was constructed based on the five independent factors (age at diagnosis, T stage, N status, subtype and radiation). The nomogram AUCs for 3- and 5-year OS (training set: 0.793 and 0.797; validation set: 0.781 and 0.823) and calibration plots exhibited good discriminative and predictive ability. Additionally, a novel risk classification system for MBC patients demonstrated that we do not have enough evidence to support the benefit effect of chemotherapy for the high-risk group as the result is not statistically significant (total population: p = 0.180; training set: p = 0.340) but could improve OS in the low-risk group (total population: p = 0.001; training set: p = 0.001). Our results suggested that chemotherapy should be selected more carefully for high-risk groups based on a combination of factors and that the possibility of exemption from chemotherapy should be confirmed by more clinical trials in the future.

Rare subtypes of triple negative breast cancer: Current understanding and future directions

Rare subtypes of triple-negative breast cancers (TNBC) are a heterogenous group of tumors, comprising 5-10% of all TNBCs. Despite accounting for an absolute number of cases in aggregate approaching that of other less common, but well studied solid tumors, rare subtypes of triple-negative disease remain understudied. Low prevalence, diagnostic challenges and overlapping diagnoses have hindered consistent categorization of these breast cancers. Here we review epidemiology, histology and clinical and molecular characteristics of metaplastic, triple-negative lobular, apocrine, adenoid cystic, secretory and high-grade neuroendocrine TNBCs. Medullary pattern invasive ductal carcinoma no special type, which until recently was a considered a distinct subtype, is also discussed. With this background, we review how applying biological principals often applied to study TNBC no special type could improve our understanding of rare TNBCs. These could include the utilization of targeted molecular approaches or disease agnostic tools such as tumor mutational burden or germline mutation-directed treatments. Burgeoning data also suggest that pathologic response to neoadjuvant therapy and circulating tumor DNA have value in understanding rare subtypes of TNBC. Finally, we discuss a framework for advancing disease-specific knowledge in this space. While the conduct of randomized trials in rare TNBC subtypes has been challenging, re-envisioning trial design and technologic tools may offer new opportunities. These include embedding rare TNBC subtypes in umbrella studies of rare tumors, retrospective review of contemporary trials, prospective identification of patients with rare TNBC subtypes entering on clinical trials and querying big data for outcomes of patients with rare breast tumors.

Comprehensive analysis of PLKs expression and prognosis in breast cancer

OBJECTIVE

A thorough examination of PLKs in breast cancer, including their expression and prognosis.

METHODS

With the help of the Oncomine database, the transcript levels of PLKs in breast cancer were examined. The changes in PLKs expression with tumor stage and indeed the relationship between PLKs expression and stage of cancer in women with breast cancer were scrutinized by using the GEPIA database. Based on Kaplan-Meier plots, breast cancer patients were assessed for their prognosis. Breast cancer gene expression and mutations were analyzed within the cBioPortal database.

RESULTS

According to Oncomine data, PLK1 and PLK4 mRNA expression levels were dramatically elevated in breast cancer patients while PLK2 and PLK5P levels were significantly downregulated. PLK1 and PLK4 expression were discovered to be greater in breast cancer tissues than in healthy tissues following analysis of the GEPIA database (P < 0.05). High levels of PLK1 and PLK4 transcripts have been linked to poor relapse-free survival rates across all patients with breast cancer according to the Kaplan-Meier Plotter database. The high levels of PLK2, PLK3, and PLK5 were associated with a higher recurrence-free survival rate. In the cBioPortal database, PLK was altered in 9.6% of breast cancer samples. Genetic alterations occurred in 15.07% of clinically counted invasive breast cancers, with mutations in 4.11%, gene amplifications in 9.59%, and gene deletion mutations in 1.37%. Additionally, the KEGG database demonstrates that PLKs are crucial for the cell cycle. The findings imply that elevated PLK1 and PLK4 expression in tissues of breast cancer might contribute significantly to the carcinogenesis of breast cancer. Moreover, PLK1 and PLK4 are highly expressed in breast cancer, and their use as molecular markers to identify high-risk subsets from patients with breast cancer is potentially possible.

CONCLUSIONS

For the precise therapy of breast cancers, PLK1 and PLK4 are potential targets, while PLK2, PLK3, and PLK5 are brand-new biomarkers for predicting the prognosis of breast cancer.

Benefit of adjuvant chemotherapy in patients with special histology subtypes of triple-negative breast cancer: a systematic review

PURPOSE

Breast cancer (BC) is a leading cause of morbidity, disability, and mortality in women, worldwide; triple-negative BC (TNBC) is a subtype traditionally associated with poorer prognosis. TNBC special histology subtypes present distinct clinical and molecular features and sensitivity to antineoplastic treatments. However, no consensus has been defined on the best adjuvant therapy. The aim of the review is to study the evidence from literature to inform the choice of adjuvant treatments in this setting.

METHODS

We systematically searched literature assessing the benefit of adjuvant chemotherapy in patients with TNBC special histotypes (PROSPERO: CRD42020153818).

RESULTS

We screened 6404 records (15 included). All the studies estimated the benefit of different chemotherapy regimens, in retrospective cohorts (median size: 69 patients (range min-max: 17-5142); median follow-up: 51 months (range: 21-268); mostly in Europe and USA). In patients with early-stage adenoid cystic TNBC, a marginal role of chemotherapy was reported. Similar for apocrine TNBC. Medullary tumors exhibited an intrinsic good prognosis with a limited role of chemotherapy, suggested to be modulated by the presence of tumor-infiltrating lymphocytes. A significant impact of chemotherapy on the overall survival was estimated in patients with metaplastic TNBC. Limitations were related to the retrospective design of all the studies and heterogeneous treatments received by the patients.

CONCLUSIONS

There is potential opportunity to consider treatment de-escalation and less intense therapies in some patients with early, special histology-type TNBC. International efforts are indispensable to validate prospective clinical decision models.

Exploring a Future for PI3K Inhibitors in Chronic Lymphocytic Leukemia

PURPOSE OF REVIEW

Treatment for chronic lymphocytic leukemia has changed substantially in the past decade with an increasing shift towards use of targeted therapies, in particular agents targeting the B cell receptor pathway. Inhibition of PI3K, downstream of the B cell receptor pathway, represents an active therapeutic strategy in CLL. Here, we explore the relevance of PI3K inhibition in CLL, examine efficacy and toxicity of approved PI3K inhibitors in CLL, examine barriers to use of PI3K inhibitors, and explore strategies to optimize use of PI3K inhibitors in CLL.

RECENT FINDINGS

Current generation PI3K inhibitors are active agents in CLL but their use may be limited by immune-mediated toxicities. Clinical trials of next generation PI3K inhibitors are ongoing and early data suggests these agents are highly active with potentially differentiated toxicity profiles. Furthermore, alternative dosing schedules may reduce toxicities of these agents. Inhibition of PI3K remains an important strategy in management of CLL and novel approaches to limit toxicities of PI3K inhibitors represent an important area of clinical research in CLL.

Venetoclax: A Review in Relapsed/Refractory Chronic Lymphocytic Leukemia

Venetoclax (Venclyxto^®; Venclexta^®) is a first-in-class, oral, selective B cell lymphoma-2 (BCL-2) inhibitor. The drug is approved in numerous countries, including those of the EU and in the USA, for the treatment of adults with relapsed or refractory (RR) chronic lymphocytic leukemia (CLL); the specific indication(s) for venetoclax may vary between individual countries. Venetoclax monotherapy or combination therapy with rituximab was an effective treatment, provided durable responses, and had a manageable safety profile in pivotal clinical trials in adults with RR CLL, including in patients with adverse prognostic factors. In combination with 6 cycles of rituximab, venetoclax (fixed 24 months' treatment) was more effective than bendamustine plus rituximab (6 cycles) in prolonging progression-free survival (PFS) and inducing undetectable minimal residual disease (uMRD) in peripheral blood (PB) and bone marrow (BM), with these benefits sustained during 36 months' follow-up. Hence, with its novel mechanism of action and convenient oral once-daily regimen, venetoclax monotherapy or fixed 24-month combination therapy with rituximab represents an important option for treating RR CLL, including in patients with del(17p) or TP53 mutation and those failing a B cell receptor (BCR) inhibitor and/or chemotherapy.

Inhibiting Bruton's Tyrosine Kinase in CLL and Other B-Cell Malignancies

Inhibitors of Bruton's tyrosine kinase (BTK), a major kinase in the B-cell receptor (BCR) signaling pathway, mediating B-cell proliferation and apoptosis, have substantially altered the management, clinical course, and outcome of patients with B-cell malignancies. This is especially true for patients with previously limited treatment options due to disease characteristics or coexisting diseases. Ibrutinib was the first orally available, nonselective and irreversible inhibitor of BTK approved for the treatment of patients with various B-cell malignancies. Newer and more selective BTK inhibitors are currently in clinical development, including acalabrutinib, which is currently US FDA approved for previously treated mantle cell lymphoma. Significant efforts are underway to investigate the optimal combinations, timing, and sequencing of BTK inhibitors with other regimens and targeted agents, and to capitalize on the immunomodulatory modes of action of BTK inhibitors to correct tumor-induced immune defects and to achieve long-lasting tumor control. This review describes the major milestones in the clinical development of BTK inhibitors in chronic lymphocytic leukemia and other B-cell malignancies, highlights the most recent long-term follow-up results, and evaluates the role of BTK inhibitors and their combination with other agents in B-cell malignancies and other indications.

Distribution of 21-Gene Recurrence Scores Among Breast Cancer Histologic Subtypes

CONTEXT

- The 21-gene recurrence score (RS) provides a probability of distant recurrence for estrogen receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancers. The utility of RS for rarer histologic subtypes of breast cancer is uncertain.

OBJECTIVE

- To determine the distribution of RS among various histologic subtypes using a population database.

DESIGN

- Women between the ages of 18 and 75 with estrogen receptor-positive, HER2-negative breast cancer and known RS results were identified using the Surveillance, Epidemiology, and End Results database. Recurrence scores were categorized into risk groups using both traditional and Trial Assigning Individualized Options for Treatment cutoffs. Multivariable logistic regression was used to determine factors associated with high-risk RS.

RESULTS

- We identified 45 618 patients with stage I to III, estrogen receptor-positive, HER2-negative breast cancer who had RS available. Overall, 3087 (7%) and 6337 (14%) of cancers were classified as high risk based on traditional and Trial Assigning Individualized Options for Treatment RS cutoffs, respectively. The proportion of high-risk RS ranged from 1% (tubular, 2 of 225) to 68% (medullary, 13 of 19) and 4% (tubular, 10 of 225) to 79% (medullary, 15 of 19) for traditional and Trial Assigning Individualized Options for Treatment cutoffs, respectively. Based on multivariable logistic regression (excluding medullary), subtypes other than invasive ductal carcinoma and papillary carcinoma were significantly associated with lower RS. The strongest predictors of a high-risk RS were higher tumor grade and negative progesterone receptor status.

CONCLUSIONS

- We identified distinct distributions of RS among different histologic subtypes of breast cancer. Excluding medullary carcinoma, histologic subtypes other than invasive ductal carcinoma and papillary carcinoma all predict lower RS.

Are BTK and PLCG2 mutations necessary and sufficient for ibrutinib resistance in chronic lymphocytic leukemia?

INTRODUCTION

Ibrutinib is the first BTK inhibitor to show efficacy in chronic lymphocytic leukemia (CLL) and is also the first BTK inhibitor to which patients have developed resistance. Mutations in BTK and PLCG2 are found in ≈80% of CLL patients with acquired resistance to ibrutinib, but it remains unclear if these mutations are merely associated with disease relapse or directly cause it. Areas covered: Unique properties of both CLL and ibrutinib that complicate attempts to definitively conclude whether BTK/PLCG2 mutations are passengers or drivers of ibrutinib-resistant disease are reviewed. Characteristics of mutations that drive drug resistance are summarized and whether BTK/PLCG2 mutations possess these is discussed. These characteristics include (1) identification in multiple patients with acquired resistance, (2) in vitro validation of drug-resistant properties, (3) mutual exclusivity with one another, (4) increasing frequency over time on drug, and (5) high frequency at the time and site of clinical relapse. Expert commentary: While BTK/PLCG2 mutations have characteristics suggesting that they can drive ibrutinib resistance, this conclusion remains formally unproven until specific inhibition of such mutations is shown to cause regression of ibrutinib-resistant CLL. Data suggest that alternative mechanisms of resistance do exist in some patients.

Management of patients with chronic lymphocytic leukemia at high risk of relapse on ibrutinib therapy

The past two decades have witnessed a paradigm shift in the management of patients with chronic lymphocytic leukemia (CLL), particularly with the introduction of targeted therapies to clinical practice. Ibrutinib is an irreversible inhibitor of Bruton's tyrosine kinase (BTK) and has shown significant efficacy and tolerability, even in heavily treated patients. Despite improvement in outcomes, patients do ultimately relapse. Those who develop disease progression on ibrutinib are a particularly high-risk population with poor outcomes. Identifying patients at higher risk of relapse while on therapy is needed for individualized clinical monitoring and timely subsequent management upon relapse. In this article, we discuss characteristics of CLL progression, risk factors for relapse on ibrutinib including clinical and molecular biomarkers, and a risk-adapted approach to identifying, monitoring, and managing CLL patients during ibrutinib therapy.

Venetoclax for the treatment of chronic lymphocytic leukemia

INTRODUCTION

Venetoclax, an orally bioavailable inhibitor of BCL-2, was approved in 2016 by the United States Food and Drug Administration (FDA) for the treatment of chronic lymphocytic leukemia (CLL) patients with 17p deletion [del(17p)], who have received at least one prior therapy. Areas covered: We focus on the mechanism of action of venetoclax and on the clinical trial data that led to the approval of venetoclax for CLL patients. We also review the studies in which this drug has being explored in combination with other anti-CLL drugs. Expert opinion: Data from early clinical trials have shown that venetoclax, as a single agent, is highly effective for relapsed/refractory CLL patients, including those cases with high-risk features. Furthermore, venetoclax seems to be an appropriate option for patients who progress on B-cell receptor (BCR) pathway kinase inhibitors. Venetoclax is also safe, with the most common serious adverse events being neutropenia. The risk of tumor lysis syndrome (TLS) can be reduced by a slow dose ramp-up, careful monitoring, and adequate prophylaxis. Ongoing trials will further clarify the safety and efficacy of venetoclax in combination with other drugs in both relapsed/refractory and untreated CLL patients.

PI3Kδ-selective and PI3Kα/δ-combinatorial inhibitors in clinical development for B-cell non-Hodgkin lymphoma

INTRODUCTION

The efficacy of the prototypical phosphatidylinositol-3-kinase (PI3K) inhibitor idelalisib for the treatment of chronic lymphocytic leukemia (CLL) and indolent non-Hodgkin lymphoma (iNHL) has led to development of multiple compounds targeting this pathway. Areas Covered: We review the hypothesized therapeutic mechanisms of PI3K inhibitors, including abrogation of B cell receptor signaling, blockade of microenvironmental pro-survival signals, and enhancement of anti-tumor immunity. We examine toxicities of idelalisib, including bacterial infections (possibly secondary to drug-induced neutropenia), opportunistic infections (possibly attributable to on-target inhibition of T cell function), and organ toxicities such as transaminitis and enterocolitis (possibly autoimmune, secondary to on-target inhibition of p110δ in regulatory T cells). We evaluate PI3K inhibitors that have entered trials for the treatment of lymphoma, focusing on agents with selectivity for PI3Kα and PI3Kδ. Expert Opinion: PI3K inhibitors, particularly those that target p110δ, have robust efficacy in the treatment of CLL and iNHL. However, idelalisib has infectious and autoimmune toxicities that limit its use. Outside of trials, idelalisib should be restricted to CLL patients with progression on ibrutinib or iNHL patients with progression on two prior therapies. Whether newer PI3K inhibitors will demonstrate differentiated toxicity profiles in comparable patient populations while retaining efficacy remains to be seen.

Awareness and current knowledge of breast cancer

Breast cancer remains a worldwide public health dilemma and is currently the most common tumour in the globe. Awareness of breast cancer, public attentiveness, and advancement in breast imaging has made a positive impact on recognition and screening of breast cancer. Breast cancer is life-threatening disease in females and the leading cause of mortality among women population. For the previous two decades, studies related to the breast cancer has guided to astonishing advancement in our understanding of the breast cancer, resulting in further proficient treatments. Amongst all the malignant diseases, breast cancer is considered as one of the leading cause of death in post menopausal women accounting for 23% of all cancer deaths. It is a global issue now, but still it is diagnosed in their advanced stages due to the negligence of women regarding the self inspection and clinical examination of the breast. This review addresses anatomy of the breast, risk factors, epidemiology of breast cancer, pathogenesis of breast cancer, stages of breast cancer, diagnostic investigations and treatment including chemotherapy, surgery, targeted therapies, hormone replacement therapy, radiation therapy, complementary therapies, gene therapy and stem-cell therapy etc for breast cancer.

Ibrutinib continues to influence the therapeutic landscape of chronic lymphocytic leukemia: new data presented at ASCO 2017

According to data presented at the 2017 American Society of Oncology (ASCO) Annual Meeting, with more than 4 years of follow-up, ibrutinib continues to provide clinical utility in chronic lymphocytic leukemia (CLL). However, treatment of CLL patients with high-risk cytogenetics features remains a challenge and the outcome of these hard-to-treat patients is dismal. At the 2017 ASCO Meeting, results of the GENUINE phase III trial showed that, by adding ublituximab, a glycoengineered, anti-CD20 type 1 monoclonal antibody, to ibrutinib, the overall response rate (ORR), complete response rate (CRR), and minimal residual disease (MRD) negativity may be improved in high-risk CLL patients. A further way to improve the results obtained with Bruton's tyrosine kinase (BTK) inhibitors is the parallel use of ibrutinib with chimeric antigen receptor (CAR) T-cell therapy. Through this investigational approach, the rate of MRD negativity was shown to be higher, implying potential eradication of CLL. These novel data indicate that ibrutinib continues to have a positive effect in CLL.

The safety of Bruton's tyrosine kinase inhibitors for the treatment of chronic lymphocytic leukemia

INTRODUCTION

The approval of ibrutinib has revolutionized the therapeutic landscape of chronic lymphocytic leukemia (CLL). Currently ibrutinib is indicated for patients that are both treatment naïve as well as those with relapsed CLL. Ibrutinib is generally well-tolerated with durable responses that improve over time in most patients. Important toxicities include atrial fibrillation and bleeding. Areas cover: This review covers the pharmacokinetics, pharmacodynamics, safety and efficacy of ibrutinib in the treatment of CLL. We also compare ibrutinib with other kinase inhibitors and chemoimmunotherapy regimens using data from clinical trials. A literature search utilized the PubMed database. Expert opinion: Despite the efficacy and tolerability of ibrutinib, important questions remain, which include selection of patients receiving ibrutinib in the first and subsequent lines of treatment, optimal dosing, sequential use of ibrutinib versus other kinase inhibitors and combination therapy. Prospective studies should incorporate minimal residual disease (MRD) status as a clinical endpoint to determine whether patients can be taken off kinase inhibitors.