Cisplatin with veliparib or placebo in metastatic triple-negative breast cancer and BRCA mutation-associated breast cancer (S1416): a randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

Poly(ADP-ribose) polymerase (PARP) inhibitors are effective in germline BRCA1 or BRCA2 (BRCA1/2) mutation-associated metastatic breast cancer. However, studies evaluating PARP inhibitors plus platinum-based chemotherapy in germline BRCA1/2-wildtype triple-negative breast cancer are scarce. A large proportion of germline BRCA1/2-wildtype triple-negative breast cancer shows homologous recombination deficiency (HRD), resulting in a BRCA-like phenotype that might render sensitivity to PARP inhibitors. The S1416 trial assessed the efficacy of cisplatin combined with the PARP inhibitor veliparib in three predefined groups of metastatic breast cancer: germline BRCA1/2-mutated, BRCA-like, and non-BRCA-like.

METHODS

S1416 was a randomised, double-blind, placebo-controlled, phase 2 trial conducted at 154 community and academic clinical sites across the USA. Eligible patients aged 18 years or older had metastatic or recurrent triple-negative breast cancer or germline BRCA1/2-associated metastatic or recurrent breast cancer, an Eastern Cooperative Oncology Group performance status of 0-2, and had received up to one line of chemotherapy for metastatic disease. Patients were randomly assigned (1:1) via the National Clinical Trials Network open interactive system with dynamic balancing on number of previous cytotoxic regimens for metastatic disease to receive intravenous cisplatin (75 mg/m2, day 1) combined with either veliparib or matching placebo (300 mg orally twice a day, days 1-14) on a 21-day cycle. Investigators, patients, and the sponsors were masked to treatment assignment; the study statisticians were unmasked. Central testing after ran domisation classified patients as having mutated or wildtype germline BRCA1/2. A biomarker panel established a priori was used to classify patients with wildtype germline BRCA1/2 into BRCA-like and non-BRCA-like phenotype groups, with BRCA-like status based on at least one of the biomarkers: genomic instability score (≥42), somatic BRCA1/2 mutations, BRCA1 promoter methylation, or non-BRCA1/2 homologous recombination repair germline mutations. The primary endpoint was investigator-assessed progression-free survival, analysed separately for the three predefined biomarker groups with a prespecified α value for each analysis. Efficacy analyses were done by intention to treat and included all eligible patients. Safety analyses of toxicities attributed to treatment included all patients who received at least one dose of veliparib or placebo. The study is ongoing and registered with ClinicalTrials.gov, NCT02595905.

FINDINGS

Between July 7, 2016, and June 15, 2019, 335 patients were enrolled and randomly assigned. 320 patients (n=162 to cisplatin plus veliparib, all women; and n=158 to cisplatin plus placebo, 157 women and one man) were eligible for efficacy evaluation. 247 patients were classified into the three biomarker groups: germline BRCA1/2-mutated (n=37), BRCA-like (n=101), and non-BRCA-like (n=109). 73 patients could not be classified due to missing biomarker information. Median follow-up was 11·1 months (IQR 5·6-20·8). In the germline BRCA1/2-mutated group, median progression-free survival was 6·2 months (95% CI 2·3-9·2) in the cisplatin plus veliparib group and 6·4 months (4·3-8·2) in the cisplatin plus placebo group (HR 0·79 [95% CI 0·38-1·67]; log-rank p=0·54). In the BRCA-like group, median progression-free survival was 5·9 months (95% CI 4·3-7·8) in the cisplatin plus veliparib group versus 4·2 months (2·3-5·0) in the cisplatin plus placebo group (HR 0·57 [95% CI 0·37-0·88]; p=0·010). In the non-BRCA-like group, median progression-free survival was 4·0 months (95% CI 2·5-4·7) in the cisplatin plus veliparib group versus 3·0 months (2·2-4·4) in the cisplatin plus placebo group (HR 0·89 [95% CI 0·60-1·33]; p=0·57). The most common grade 3 or worse adverse events attributed to treatment were neutropenia (71 [46%] of 155 patients in the cisplatin plus veliparib group vs 29 [20%] of 147 in the cisplatin plus placebo group), leukopenia (42 [27%] vs 11 [7%]), anaemia (35 [23%] vs 12 [8%]), and thrombocytopenia (29 [19%] vs four [3%]). Serious adverse events attributed to treatment occurred in 48 (31%) patients in the cisplatin plus veliparib group and 53 (36%) patients in the cisplatin plus placebo group. Treatment-related adverse events led to death in one patient in the cisplatin plus veliparib group (sepsis) and one patient in the cisplatin plus placebo group (acute kidney injury due to cisplatin plus heart failure from previous doxorubicin exposure).

INTERPRETATION

The addition of veliparib to cisplatin significantly improved progression-free survival in patients with BRCA-like metastatic triple-negative breast cancer, but not in patients with non-BRCA-like metastatic breast cancer. PARP inhibitors combined with platinum-based chemotherapy should be explored further in BRCA-like triple-negative breast cancer.

FUNDING

National Cancer Institute and National Institute of General Medical Sciences (US National Institutes of Health); AbbVie; Myriad Genetics; the Biomarker, Imaging, and Quality of Life Studies Funding Program (awarded by the National Cancer Institute); and The University of Kansas Cancer Center.

A Pragmatic Cluster-Randomized Trial of a Standing Order Entry Intervention for Colony-Stimulating Factor Use Among Patients at Intermediate Risk for Febrile Neutropenia

PURPOSE

Primary prophylactic colony-stimulating factors (PP-CSFs) are prescribed to reduce febrile neutropenia (FN) but their benefit for intermediate FN risk regimens is uncertain. Within a pragmatic, randomized trial of a standing order entry (SOE) PP-CSF intervention, we conducted a substudy to evaluate the effectiveness of SOE for patients receiving intermediate-risk regimens.

METHODS

TrACER was a cluster randomized trial where practices were randomized to usual care or a guideline-based SOE intervention. In the primary study, sites were randomized 3:1 to SOE of automated PP-CSF orders for high FN risk regimens and alerts against PP-CSF use for low-risk regimens versus usual care. A secondary 1:1 randomization assigned 24 intervention sites to either SOE to prescribe or an alert to not prescribe PP-CSF for intermediate-risk regimens. Clinicians were allowed to over-ride the SOE. Patients with breast, colorectal, or non-small-cell lung cancer were enrolled. Mixed-effect logistic regression models were used to test differences between randomized sites.

RESULTS

Between January 2016 and April 2020, 846 eligible patients receiving intermediate-risk regimens were registered to either SOE to prescribe (12 sites: n = 542) or an alert to not prescribe PP-CSF (12 sites: n = 304). Rates of PP-CSF use were higher among sites randomized to SOE (37.1% v 9.9%, odds ratio, 5.91; 95% CI, 1.77 to 19.70; P = .0038). Rates of FN were low and identical between arms (3.7% v 3.7%).

CONCLUSION

Although implementation of a SOE intervention for PP-CSF significantly increased PP-CSF use among patients receiving first-line intermediate-risk regimens, FN rates were low and did not differ between arms. Although this guideline-informed SOE influenced prescribing, the results suggest that neither SOE nor PP-CSF provides sufficient benefit to justify their use for all patients receiving first-line intermediate-risk regimens.

Effects of a Guideline-Informed Clinical Decision Support System Intervention to Improve Colony-Stimulating Factor Prescribing: A Cluster Randomized Clinical Trial

IMPORTANCE

Colony-stimulating factors are prescribed to patients undergoing chemotherapy to reduce the risk of febrile neutropenia. Research suggests that 55% to 95% of colony-stimulating factor prescribing is inconsistent with national guidelines.

OBJECTIVE

To examine whether a guideline-based standing order for primary prophylactic colony-stimulating factors improves use and reduces the incidence of febrile neutropenia.

DESIGN, SETTING, AND PARTICIPANTS

This cluster randomized clinical trial, the Trial Assessing CSF Prescribing Effectiveness and Risk (TrACER), involved 32 community oncology clinics in the US. Participants were adult patients with breast, colorectal, or non-small cell lung cancer initiating cancer therapy and enrolled between January 2016 and April 2020. Data analysis was performed from July to October 2021.

INTERVENTIONS

Sites were randomized 3:1 to implementation of a guideline-based primary prophylactic colony-stimulating factor standing order system or usual care. Automated orders were added for high-risk regimens, and an alert not to prescribe was included for low-risk regimens. Risk was based on National Comprehensive Cancer Network guidelines.

MAIN OUTCOMES AND MEASURES

The primary outcome was to find an increase in colony-stimulating factor use among high-risk patients from 40% to 75%, a reduction in use among low-risk patients from 17% to 7%, and a 50% reduction in febrile neutropenia rates in the intervention group. Mixed model logistic regression adjusted for correlation of outcomes within a clinic.

RESULTS

A total of 2946 patients (median [IQR] age, 59.0 [50.0-67.0] years; 2233 women [77.0%]; 2292 White [79.1%]) were enrolled; 2287 were randomized to the intervention, and 659 were randomized to usual care. Colony-stimulating factor use for patients receiving high-risk regimens was high and not significantly different between groups (847 of 950 patients [89.2%] in the intervention group vs 296 of 309 patients [95.8%] in the usual care group). Among high-risk patients, febrile neutropenia rates for the intervention (58 of 947 patients [6.1%]) and usual care (13 of 308 patients [4.2%]) groups were not significantly different. The febrile neutropenia rate for patients receiving high-risk regimens not receiving colony-stimulating factors was 14.9% (17 of 114 patients). Among the 585 patients receiving low-risk regimens, colony-stimulating factor use was low and did not differ between groups (29 of 457 patients [6.3%] in the intervention group vs 7 of 128 patients [5.5%] in the usual care group). Febrile neutropenia rates did not differ between usual care (1 of 127 patients [0.8%]) and the intervention (7 of 452 patients [1.5%]) groups.

CONCLUSIONS AND RELEVANCE

In this cluster randomized clinical trial, implementation of a guideline-informed standing order did not affect colony-stimulating factor use or febrile neutropenia rates in high-risk and low-risk patients. Overall, use was generally appropriate for the level of risk. Standing order interventions do not appear to be necessary or effective in the setting of prophylactic colony-stimulating factor prescribing.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02728596.

E2112: Randomized Phase III Trial of Endocrine Therapy Plus Entinostat or Placebo in Hormone Receptor-Positive Advanced Breast Cancer. A Trial of the ECOG-ACRIN Cancer Research Group

PURPOSE

Endocrine therapy resistance in advanced breast cancer remains a significant clinical problem that may be overcome with the use of histone deacetylase inhibitors such as entinostat. The ENCORE301 phase II study reported improvement in progression-free survival (PFS) and overall survival (OS) with the addition of entinostat to the steroidal aromatase inhibitor (AI) exemestane in advanced hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer.

PATIENTS AND METHODS

E2112 is a multicenter, randomized, double-blind, placebo-controlled phase III study that enrolled men or women with advanced HR-positive, HER2-negative breast cancer whose disease progressed after nonsteroidal AI. Participants were randomly assigned to exemestane 25 mg by mouth once daily and entinostat (EE) or placebo (EP) 5 mg by mouth once weekly. Primary end points were PFS by central review and OS. Secondary end points included safety, objective response rate, and lysine acetylation change in peripheral blood mononuclear cells between baseline and cycle 1 day 15.

RESULTS

Six hundred eight patients were randomly assigned during March 2014-October 2018. Median age was 63 years (range 29-91), 60% had visceral disease, and 84% had progressed after nonsteroidal AI in metastatic setting. Previous treatments included chemotherapy (60%), fulvestrant (30%), and cyclin-dependent kinase inhibitor (35%). Most common grade 3 and 4 adverse events in the EE arm included neutropenia (20%), hypophosphatemia (14%), anemia (8%), leukopenia (6%), fatigue (4%), diarrhea (4%), and thrombocytopenia (3%). Median PFS was 3.3 months (EE) versus 3.1 months (EP; hazard ratio = 0.87; 95% CI, 0.67 to 1.13; P = .30). Median OS was 23.4 months (EE) versus 21.7 months (EP; hazard ratio = 0.99; 95% CI, 0.82 to 1.21; P = .94). Objective response rate was 5.8% (EE) and 5.6% (EP). Pharmacodynamic analysis confirmed target inhibition in entinostat-treated patients.

CONCLUSION

The combination of exemestane and entinostat did not improve survival in AI-resistant advanced HR-positive, HER2-negative breast cancer.

Breast Cancer Screening Among Medically Underserved Women in New Mexico: Potential for Lower Recall Rates with Digital Breast Tomosynthesis

Introduction: Digital breast tomosynthesis (DBT) may decrease recall rates (RRs) and improve positive predictive values (PPVs) and cancer detection rates (CDRs) versus full-field digital mammography (FFDM). The value of DBT has not been assessed in New Mexico's rural and minority population. Objectives of this study were to compare RRs, CDRs, and PPVs using FFDM+DBT versus FFDM in screening mammograms at the University of New Mexico between 2013 and 2016 and to qualitatively evaluate patient decision-making regarding DBT. Materials and Methods: RRs, CDRs, and PPVs with 95% confidence intervals and relative risk were calculated from 35,147 mammograms. The association between relative risk and mammography approach was tested using Pearson's chi-square test. Twenty women undergoing screening were interviewed for qualitative evaluation of decision-making. Results: From 2013 to 2016, RRs were 8.4% and 11.1% for FFDM+DBT and FFDM, respectively. The difference in RRs became more pronounced with time. No significant difference was observed in PPVs or CDRs. Qualitative interviews revealed that the majority had limited prior knowledge of DBT and relied on provider recommendations. Conclusion: In New Mexico women undergoing screening mammography, a 30% relative risk reduction in RRs was observed with FFDM+DBT. Qualitative interviews suggest that women are aware of and receptive to DBT, assuming adequate educational support. Clinical Trials.gov ID: NCT03979729.