Gene Alterations in Triple-Negative Breast Cancer Patients in a Phase I/II Study of Eribulin and Olaparib Combination Therapy

Multifunctional Graphene Oxide Nanodelivery Platform for Breast Cancer Treatment

Background

Breast cancer (BC) has the highest global prevalence among all malignancies in women and the second highest prevalence in the overall population. Paclitaxel (PTX), a tricyclic diterpenoid, is effective against BC. However, its poor solubility in water and the allergenicity of its dissolution medium limited its clinical application.

Methods

In this work, we established a multifunctional graphene oxide (GO) tumor-targeting drug delivery system using nanosized graphene oxide (nGO) modified with D-tocopherol polyethylene glycol succinate (TPGS) and arginine-glycine-aspartic acid (RGD) for PTX loading.

Results

The obtained RGD-TPGS-nGO-PTX was 310.20±19.86 nm in size; the polydispersity index (PDI) and zeta potential were 0.21±0.020 and -23.42 mV, respectively. The mean drug loading capacity of RGD-TPGS-nGO-PTX was 48.78%. RGD-TPGS-nGO-PTX showed satisfactory biocompatibility and biosafety and had no significant toxic effects on zebrafish embryos. Importantly, it exerted excellent cytotoxicity against MDA-MB-231 cells, reversed multi-drug resistance (MDR) in MCF-7/ADR cells, and showed significant anti-tumor efficacy in tumor-bearing nude mice.

Conclusion

These findings strongly suggested that the multifunctional GO tumor-targeting drug delivery system RGD-TPGS-nGO-PTX could be used in clinical settings to improve PTX delivery, reverse MDR and increase the therapeutic efficacy of BC treatment.

Associations with response to Poly(ADP-ribose) Polymerase (PARP) inhibitors in patients with metastatic breast cancer

PARP inhibitors (PARPi) have modest antitumor activity in patients with advanced breast cancer and mutation in BRCA. It is unclear whether some subgroups derive greater benefit from treatment. MEDLINE and EMBASE were searched from inception to March 2021 to identify trials of PARPi in patients with metastatic breast cancer. Objective response rate (ORR) and clinical benefit rate (CBR) to PARPi were extracted and pooled in a meta-analysis using the Mantel Haenszel random effects model. Meta-regression explored the influence of patient and tumor characteristics on ORR and CBR. For randomized trials, hazard ratio comparing PARPi to control therapy were pooled using inverse variance and random effects. Analysis included 43 studies comprising 2409 patients. Among these, 1798 (75%) patients had BRCA mutations and 1146 (48%) were triple negative. In 10 studies (28%; n = 680 patients), the PARPi was given in combination with platinum-based chemotherapy. Weighted mean ORR was 45%; 64% when combined with platinum vs 37% with PARPi monotherapy (p < 0.001). Previous platinum-based chemotherapy was associated with lower ORR (p = 0.02). Compared to standard chemotherapy, progression-free survival was improved (HR 0.64, p < 0.001), but there was no difference in overall survival (HR 0.87, p = 0.06). There were no differences in ORR or CBR between BRCA1 and BRCA2 mutations. PARPi are more active in combination with platinum than as monotherapy, with lower response if given as monotherapy after platinum exposure. Significant improvements in ORR translated to modest improvement in progression-free, but not overall survival. There was no association between ORR and BRCA mutations.

Efficacy and Safety of PARP Inhibitors in Advanced or Metastatic Triple-Negative Breast Cancer: A Systematic Review and Meta-Analysis

Purpose

Poly (ADP-ribose) polymerase (PARP) inhibitors have shown promising results in metastatic triple-negative breast cancers (TNBCs). We therefore performed a systematic review and meta-analysis to evaluate the efficacy and safety of this drug in patients with advanced or metastatic TNBC.

Methods

A systematic literature search of PubMed, Embase, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials for synonyms of "PARP inhibitors" and "breast cancer" was carried out. All published phase II/III clinical studies of PARP inhibitors in patients with advanced/metastatic TNBC were screened. Data were extracted independently by two authors and analyzed using Review Manager software version 5.3. End points include overall response rate (ORR), progression-free survival (PFS), and adverse events.

Results

Ten clinical trials were identified, with a total of 1,495 patients included. Pooled analyses showed that PARP inhibitors could provide a significant improvement of ORR [risk ratio (RR) = 2.00; 95% confidence interval (CI), 1.14-3.50; p = 0.02) and PFS [hazard ratio (HR) = 0.68; 95%Cl, 0.59-0.77; p < 0.0001) compared to chemotherapy in the whole population. In subgroup analysis, patients with BRCA mutation had a higher objective response to PARP inhibitor, with an RR of 2.85 (95%CI, 1.34-6.06; p = 0.007) compared to BRCA wild-type patients. However, no significant difference in ORR was observed between the homologous recombination deficiency (HRD) positive and non-HRD subgroups (RR = 1.82; 95%CI, 0.81-4.08; p = 0.14). Hematological toxicity is a common adverse event of PARP inhibitors.

Conclusions

PARP inhibitors are effective options for the treatment of patients with advanced or metastatic TNBC. Compared with patients without germline BRCA mutation, patients with germline BRCA mutation could benefit more from PARP inhibitors. In clinical setting, hematological toxicity associated with PARP inhibitors should be monitored regularly.

BRCA1 promoter methylation in breast cancer patients is associated with response to olaparib/eribulin combination therapy

BACKGROUND

A PARP inhibitor is effective in breast cancer patients with BRCA1/2 germline mutations, and in cell lines with BRCA1 promoter methylation. However, its efficacy in breast cancer patients with BRCA1 promoter methylation is still unknown.

METHODS

Biopsy samples were obtained from 32 triple-negative breast cancer (TNBC) patients treated with eribulin/olaparib combination therapy in a clinical trial (UMINID: 000009498) and analyzed for their mutations by FoundationOne CDx. DNA methylation was evaluated by quantitative methylation-specific PCR and bisulfite sequencing, and its level was adjusted for tumor cell fraction.

RESULTS

Among 20 TNBC patients evaluable for both methylation and mutations, one (5%) and five (25%) patients had a high (> 80%) and low (30-80%) BRCA1 promoter methylation levels, respectively. One patient with a high methylation level, also having a BRCA2 mutation of unknown significance, displayed complete response. Among the 5 patients with low methylation levels, only one patient with a BRCA2 mutation of unknown significance displayed long-lasting disease control (24 weeks). Patients with a BRCA1 or BRCA2 mutation, or high BRCA1 promoter methylation showed better 6-month progression-free survival (PFS) compared with the other patients (P = 0.009).

CONCLUSION

Quantitative methylation analysis suggested that addition of homozygous BRCA1 promoter methylation to mutations may more accurately identify TNBC patients who would benefit from olaparib/eribulin combination therapy. (209 words).

53BP1 Accumulation in Circulating Tumor Cells Identifies Chemotherapy-Responsive Metastatic Breast Cancer Patients

Evidence suggests that the DNA end-binding protein p53-binding protein 1 (53BP1) is down-regulated in subsets of breast cancer. Circulating tumor cells (CTCs) provide accessible “biopsy material” to track cell traits and functions and their alterations during treatment. Here, we prospectively monitored the 53BP1 status in CTCs from 67 metastatic breast cancer (MBC) patients with HER2- CTCs and known hormone receptor (HR) status of the primary tumor and/or metastases before, during, and at the end of chemotherapeutic treatment with Eribulin. Nuclear 53BP1 staining and genomic integrity were evaluated by immunocytochemical and whole-genome-amplification-based polymerase chain reaction (PCR) analysis, respectively. Comparative analysis of CTCs from patients with triple-negative and HR+ tumors revealed elevated 53BP1 levels in CTCs from patients with HR+ metastases, particularly following chemotherapeutic treatment. Differences in nuclear 53BP1 signals did not correlate with genomic integrity in CTCs at baseline or with nuclear γH2AX signals in MBC cell lines, indicating that 53BP1 detected features beyond DNA damage. Kaplan–Meier analysis revealed an increasing association between nuclear 53BP1-positivity and progression-free survival (PFS) during chemotherapy until the final visit. Our data suggest that 53BP1 detection in CTCs could be a useful marker to capture dynamic changes of chemotherapeutic responsiveness in triple-negative and HR+ MBC.