PARP Inhibitors for the Treatment of BRCA1/2-Mutated Metastatic Breast Cancer: A Systematic Review and Meta-analysis

BACKGROUND: The PARP inhibitors (PARPis) olaparib and talazoparib are currently approved for the treatment of deleterious germline BRCA1/2-mutated (gBRCA+) metastatic breast cancer (MBC). These approvals were based on improvements in progression-free survival (PFS) observed in two randomized controlled trials (RCTs). Other PARPis, such as veliparib and niraparib, have also been studied. We conducted this meta-analysis of RCTs to assess the PFS and overall survival (OS) benefits of PARPis in gBRCA + MBC. METHODS: We performed a systematic search for RCTs using the Cochrane Library, PubMed, Embase, and Web of Science databases up to March 2021. Only phase II and III RCTs evaluating PFS and OS for PARPis alone or in combination with chemotherapy (CT) and comparing the findings with standard CT were included in this meta-analysis. Pooled analysis of the hazard ratio (HR) was performed with RevMan v5.4 using a random effects method. RESULTS: Five RCTs with a total of 1563 BRCA-mutated MBC patients were included in this meta-analysis. Temozolomide was used in the treatment arm in the BROCADE trial. Since temozolomide has limited effects on breast cancer, this arm was excluded from our meta-analysis. A statistically significant increase in PFS was observed in the PARPi group compared to the standard CT group (HR, 0.64; 95% CI, 0.56-0.74; P \u3c 0.00001). However, the differences in OS did not reach statistical significance (HR, 0.89; 95% CI, 0.77-1.02; P = 0.09). Moreover, differences were not observed in the adverse event profile between the two groups (odds ratio, 1.18; 95% CI, 0.84-1.64; P = 0.33). CONCLUSION: The results of our meta-analysis confirm the previously reported PFS benefit of PARPis over standard CT. PARPis lead to superior PFS in gBRCA + MBC when used alone or in combination with standard CT. The OS benefit is similar between PARPis and standard CT. Ongoing trials are evaluating the benefits of PARPis in early stage gBRCA + BC

AKT/mTOR Signaling Modulates Resistance to Endocrine Therapy and CDK4/6 Inhibition in Metastatic Breast Cancers

Endocrine therapy (ET) in combination with CDK4/6 inhibition is routinely used as first-line treatment for HR+/HER2− metastatic breast cancer (MBC) patients. However, 30–40% of patients quickly develop disease progression. In this open-label multicenter clinical trial, we utilized a hypothesis-driven protein/phosphoprotein-based approach to identify predictive markers of response to ET plus CDK4/6 inhibition in pre-treatment tissue biopsies. Pathway-centered signaling profiles were generated from microdissected tumor epithelia and surrounding stroma/immune cells using the reverse phase protein microarray. Phosphorylation levels of the CDK4/6 downstream substrates Rb (S780) and FoxM1 (T600) were higher in patients with progressive disease (PD) compared to responders (p = 0.02). Systemic PI3K/AKT/mTOR activation in tumor epithelia and stroma/immune cells was detected in patients with PD. This activation was not explained by underpinning genomic alterations alone. As the number of FDA-approved targeted compounds increases, functional protein-based signaling analyses may become a critical component of response prediction and treatment selection for MBC patients

A Telehealth-Delivered Tai Chi Intervention (TaiChi4Joint) for Managing Aromatase Inhibitor-Induced Arthralgia in Patients With Breast Cancer During COVID-19: Longitudinal Pilot Study

Background: Estrogen receptor-positive breast cancer is the most common type of breast cancer in postmenopausal women. Aromatase inhibitors (AIs) are the endocrine therapy of choice recommended for these patients. Up to 50% of those treated with an AI develop arthralgia, often resulting in poor adherence and decreased quality of life. Objective: The study is a single-arm longitudinal pilot study aiming to evaluate the safety, feasibility, acceptability, and potential efficacy of TaiChi4Joint, a remotely delivered 12-week tai chi intervention designed to relieve AI-induced joint pain. Methods: Women diagnosed with stage 0-III breast cancer who received an AI for at least 2 months and reported arthralgia with a ≥4 score on a 0 to 10 scale for joint pain were eligible for study enrollment. Participants were encouraged to join tai chi classes delivered over Zoom three times a week for 12 weeks. Program engagement strategies included using a private Facebook study group and a Box cloud for archiving live class recordings. The program uses SMS text messaging and emails with periodic positive quotes and evidence-based information on tai chi for facilitating community bonding and class attendance. Participants were invited to complete the following assessments at baseline and at 1-, 2-, and 3-month intervals from study enrollment: Brief Pain Inventory, Western Ontario and McMaster University Osteoarthritis Index (WOMAC), The Australian Canadian Osteoarthritis Hand Index (AUSCAN), Fatigue Symptom Inventory, Hot Flash Related Daily Interference Scale (HFRDIS), Pittsburgh Sleep Quality Index (PSQI), and Center for Epidemiological Studies-Depression (CES-D). Results: A total of 55 eligible patients were invited to participate, and 39 (71%) consented and completed the baseline assessments. Participants attended 61% (median) of the suggested classes, with no tai chi-related adverse events reported. Of the 39 participants, 22 completed the 3-month follow-up assessment with a 56% retention rate. Study participants reported improvement from baseline compared to 3 months as follows (paired t test): Brief Pain Inventory (P\u3c.001), AUSCAN pain subscale (P=.007), AUSCAN function subscale (P=.004), Fatigue Symptom Inventory (P=.004) and PSQI (P\u3c.001), and HFRDIS (P=.02) and CES-D (P\u3c.001). In particular, for our primary end point of interest, improvements in hip and knee symptoms, measured by WOMAC\u27s three subscales, were clinically meaningful and statistically significant when adjusted for multiple comparisons from baseline to 3 months post intervention. Conclusions: The COVID-19 global pandemic has resulted in the need to rethink how mind-body therapies can be delivered. This study demonstrated the feasibility, acceptability, and potential efficacy of a telehealth-based tai chi intervention for reducing AI-induced arthralgia. The intervention decreased patient-reported pain and stiffness, and improved sleep quality and depressive symptoms. Fully powered, large, telehealth-based tai chi trials for AI-associated arthralgia are needed considering our promising findings. Trial registration: ClinicalTrials.gov NCT04716920; https://www.clinicaltrials.gov/ct2/show/NCT04716920

PALINA: A phase II safety study of palbociclib in combination with letrozole or fulvestrant in African American women with hormone receptor positive HER2 negative advanced breast cancer

Palbociclib has been shown to be a highly effective therapy in hormone receptor positive metastatic breast cancer when used in combination with letrozole or fulvestrant. Grade 3/4 neutropenia is a common side effect although febrile neutropenia is relatively uncommon. Insufficient data exist to describe the hematological safety of palbociclib in African American women (AAW) known to have a high incidence of benign ethnic neutropenia (BEN). PALOMA 1, 2 and 3, the initial phase II/III studies that led to the U.S. Food and Drug Administration (FDA) approval of palbociclib in metastatic breast cancer, only included participants with baseline absolute neutrophil count (ANC) of 1500/mm3 or higher. African American women (AAW) were underrepresented in the PALOMA trials and this may be partially explained by strict requirements for minimal ANC ≥1500/mm3. The ANC of 1500/mm3 for initiation of treatment in those with BEN has been previously challenged. In this study, we propose to lower the ANC cutoff for enrollment to 1000/mm3. PALINA (NCT02692755) is a phase II, single arm, multicenter clinical trial that will enroll 35 patients. The primary endpoint is to assess the proportion of patients who complete therapy without the development of febrile neutropenia or treatment discontinuation due to neutropenia. The secondary endpoints include number of patients who required dose delays or dose reductions in palbociclib attributed to neutropenia, rate of grade 3/4 neutropenia, clinical benefit rate at 24 weeks, the association between metabolite and exosomal signature with disease response and the association between baseline ANC prior to cancer diagnosis and the Duffy Null polymorphism (SNP rs2814778) with hematological safety. PALINA will provide important information about the hematologic safety of palbociclib in AAW with advanced breast cancer. Keywords: Palbociclib, Letrozole, Fulvestrant, African-America

Whole-exome sequencing identifies somatic mutations and intratumor heterogeneity in inflammatory breast cancer.

Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer. Although it is a rare subtype, IBC is responsible for roughly 10% of breast cancer deaths. In order to obtain a better understanding of the genomic landscape and intratumor heterogeneity (ITH) in IBC, we conducted whole-exome sequencing of 16 tissue samples (12 tumor and four normal samples) from six hormone-receptor-positive IBC patients, analyzed somatic mutations and copy number aberrations, and inferred subclonal structures to demonstrate ITH. Our results showed that KMT2C was the most frequently mutated gene (42%, 5/12 samples), followed by HECTD1, LAMA3, FLG2, UGT2B4, STK33, BRCA2, ACP4, PIK3CA, and DNAH8 (all nine genes tied at 33% frequency, 4/12 samples). Our data indicated that PTEN and FBXW7 mutations may be considered driver gene mutations for IBC. We identified various subclonal structures and different levels of ITH between IBC patients, and mutations in the genes EIF4G3, IL12RB2, and PDE4B may potentially generate ITH in IBC