Oxidative Phosphorylation Is a Metabolic Vulnerability in Chemotherapy-Resistant Triple-Negative Breast Cancer

Oxidative phosphorylation (OXPHOS) is an active metabolic pathway in many cancers. RNA from pretreatment biopsies from patients with triple-negative breast cancer (TNBC) who received neoadjuvant chemotherapy demonstrated that the top canonical pathway associated with worse outcome was higher expression of OXPHOS signature. IACS-10759, a novel inhibitor of OXPHOS, stabilized growth in multiple TNBC patient-derived xenografts (PDX). On gene expression profiling, all of the sensitive models displayed a basal-like 1 TNBC subtype. Expression of mitochondrial genes was significantly higher in sensitive PDXs. An in vivo functional genomics screen to identify synthetic lethal targets in tumors treated with IACS-10759 found several potential targets, including CDK4. We validated the antitumor efficacy of the combination of palbociclib, a CDK4/6 inhibitor, and IACS-10759 in vitro and in vivo. In addition, the combination of IACS-10759 and multikinase inhibitor cabozantinib had improved antitumor efficacy. Taken together, our data suggest that OXPHOS is a metabolic vulnerability in TNBC that may be leveraged with novel therapeutics in combination regimens. SIGNIFICANCE: These findings suggest that triple-negative breast cancer is highly reliant on OXPHOS and that inhibiting OXPHOS may be a novel approach to enhance efficacy of several targeted therapies.

Risk-Stratified Pancreatectomy Clinical Pathway Implementation and Delayed Gastric Emptying

BACKGROUND

Delayed gastric emptying (DGE) is a frequent complication after pancreaticoduodenectomy (PD) that impairs recovery and quality of life. The purpose of this study was to assess the impact risk-stratified pancreatectomy clinical pathways (RSPCPs) had on delayed gastric emptying (DGE) and identify factors associated with DGE in a contemporary period.

METHODS

A single-institution, prospective database was queried for consecutive PDs during July 2011-November 2019. Using international definitions, DGE rates were compared between periods before and after RSPCPs were implemented in 2016, classifying patients according to their postoperative pancreatic fistula (POPF) risk. Risk factors were analyzed to identify modifiable targets.

RESULTS

Among 724 elective PDs, 552 (76%) were for adenocarcinoma and 172 (24%) for other diagnoses. Of the 197 (27%) patients with DGE, 119 (16%) had type A, 41 (6%) type B, and 38 (5%) type C. In the overall cohort, DGE rates were higher with pylorus-preserving vs. classic hand-sewn reconstruction (odds ratio [OR] - 1.84; p < 0.001), postoperative abscess (OR - 2.54; p = 0.003), and non-white patients (p = 0.007), but lower after implementation of RSPCPs (OR - 0.34, p < 0.001). In the 374 patients treated with RSPCPs, only 17% (n = 65/374) developed DGE. Patients with protocol-compliant NGT removal ≤ 48 h were less likely to experience DGE (OR - 1.46, p = 0.042).

CONCLUSION

Our data suggest that implementation of preoperatively assigned RSPCPs as a care bundle was the most important factor in decreasing DGE. These gains were accentuated in patients who underwent early nasogastric tube removal and had a classic hand-sewn gastro-jejunostomy reconstruction. Application of these modifiable factors is generalizable with low implementation barriers.

Abstract C016: Oxidative phosphorylation is a metabolic vulnerability in chemotherapy resistant triple negative breast cancer

There is a pressing need to identify improved therapies for triple negative breast cancers (TNBC) resistant to standard chemotherapy. To identify potential molecular targets, we performed RNA sequencing of pre-treatment biopsies from 43 patients with operable TNBC who received neoadjuvant anthracycline and taxane-based chemotherapy. Ingenuity pathway analysis demonstrated that the top canonical pathway associated with higher likelihood of recurrence was higher expression of oxidative phosphorylation (OXPHOS) signature. We therefore sought to determine the efficacy of IACS-10759, a potent inhibitor of OXPHOS, in 10 TNBC patient-derived xenografts (PDX), 8 generated from chemotherapy-resistant tumors. Partial response was observed in one PDX model and prolonged disease stabilization in 5 of 10 PDXs. PDXs with higher expression of protein coding mitochondrial genes were more sensitive to IACS-10759. AXL overexpression was associated with intrinsic and acquired IACS-10759 resistance. The combination of cabozantinib, a multi-kinase inhibitor targeting AXL, with IACS-10759 significantly improved responses in TNBC PDXs. In contrast, selective AXL inhibitor BGB324 or knockdown of AXL did not enhance IACS-10759 sensitivity. In addition, an in vivo synthetic lethality screen identified CDK4, PARP1 and PARP2 as potential combination targets for IACS-10759. Palbociclib as well as talazoparib enhanced growth inhibitory effect of OXPHOS inhibition in vitro and in vivo. Our data suggests that OXPHOS is a promising target in chemoresistant TNBC. IACS-10759 is currently in Phase 1 testing, including TNBC. Further work is needed to determine the optimal biomarker-driven combination partners.

Citation Format: Kurt Evans, Stacy Moulder, Erkan Yuca, Stephen Scott, Natalia Paez Arango, Maryam Shariati, Christopher P Vellano, Turcin Saridogan, Xiaofeng Zheng, Ana Maria Gonzalez-Angulo, Ming Zhao, Xiaoping Su, Coya Tapia, Ken Chen, Argun Akcakanat, Charles M Perou, Bora Lim, Debu Tripathy, Timothy A Yap, Maria E Di Francesco, Giulio Draetta, Philip Jones, Joe Marszalek, Funda Meric-Bernstam. Oxidative phosphorylation is a metabolic vulnerability in chemotherapy resistant triple negative breast cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C016. doi:10.1158/1535-7163.TARG-19-C016

A Population of Heterogeneous Breast Cancer Patient-Derived Xenografts Demonstrate Broad Activity of PARP Inhibitor in BRCA1/2 Wild-Type Tumors

Background: Breast cancer patients who do not respond to neoadjuvant therapy have a poor prognosis. There is a pressing need for novel targets and models for preclinical testing. Here we report characterization of breast cancer patient-derived xenografts (PDX) largely generated from residual tumors following neoadjuvant chemotherapy.Experimental Design: PDXs were derived from surgical samples of primary or locally recurrent tumors. Normal and tumor DNA sequencing, RNASeq, and reverse phase protein arrays (RPPA) were performed. Phenotypic profiling was performed by determining efficacy of a panel of standard and investigational agents.Results: Twenty-six PDXs were developed from 25 patients. Twenty-two were generated from residual disease following neoadjuvant chemotherapy, and 24 were from triple-negative breast cancer (TNBC). These PDXs harbored a heterogeneous set of genomic alterations and represented all TNBC molecular subtypes. On RPPA, PDXs varied in extent of PI3K and MAPK activation. PDXs also varied in their sensitivity to chemotherapeutic agents. PI3K, mTOR, and MEK inhibitors repressed growth but did not cause tumor regression. The PARP inhibitor talazoparib caused dramatic regression in five of 12 PDXs. Notably, four of five talazoparib-sensitive models did not harbor germline BRCA1/2 mutations, but several had somatic alterations in homologous repair pathways, including ATM deletion and BRCA2 alterations.Conclusions: PDXs capture the molecular and phenotypic heterogeneity of TNBC. Here we show that PARP inhibition can have activity beyond germline BRCA1/2 altered tumors, causing regression in a variety of molecular subtypes. These models represent an opportunity for the discovery of rational combinations with targeted therapies and predictive biomarkers. Clin Cancer Res; 23(21); 6468-77. ©2017 AACR.

A feasibility study of returning clinically actionable somatic genomic alterations identified in a research laboratory

PURPOSE

Molecular profiling performed in the research setting usually does not benefit the patients that donate their tissues. Through a prospective protocol, we sought to determine the feasibility and utility of performing broad genomic testing in the research laboratory for discovery, and the utility of giving treating physicians access to research data, with the option of validating actionable alterations in the CLIA environment.

EXPERIMENTAL DESIGN

1200 patients with advanced cancer underwent characterization of their tumors with high depth hybrid capture sequencing of 201 genes in the research setting. Tumors were also tested in the CLIA laboratory, with a standardized hotspot mutation analysis on an 11, 46 or 50 gene platform.

RESULTS

527 patients (44%) had at least one likely somatic mutation detected in an actionable gene using hotspot testing. With the 201 gene panel, 945 patients (79%) had at least one alteration in a potentially actionable gene that was undetected with the more limited CLIA panel testing. Sixty-four genomic alterations identified on the research panel were subsequently tested using an orthogonal CLIA assay. Of 16 mutations tested in the CLIA environment, 12 (75%) were confirmed. Twenty-five (52%) of 48 copy number alterations were confirmed. Nine (26.5%) of 34 patients with confirmed results received genotype-matched therapy. Seven of these patients were enrolled onto genotype-matched targeted therapy trials.

CONCLUSION

Expanded cancer gene sequencing identifies more actionable genomic alterations. The option of CLIA validating research results can provide alternative targets for personalized cancer therapy.

Selinexor (KPT-330) demonstrates anti-tumor efficacy in preclinical models of triple-negative breast cancer

BACKGROUND

Selinexor (KPT-330) is an oral agent that has been shown to inhibit the nuclear exporter XPO1. Given the pressing need for novel therapies for triple-negative breast cancer (TNBC), we sought to determine the antitumor effects of selinexor in vitro and in vivo.

METHODS

Twenty-six breast cancer cell lines of different breast cancer subtypes were treated with selinexor in vitro. Cell proliferation assays were used to measure the half-maximal inhibitory concentration (IC₅₀) and to test the effects in combination with chemotherapy. In vivo efficacy was tested both as a single agent and in combination therapy in TNBC patient-derived xenografts (PDXs).

RESULTS

Selinexor demonstrated growth inhibition in all 14 TNBC cell lines tested; TNBC cell lines were more sensitive to selinexor (median IC₅₀ 44 nM, range 11 to 550 nM) than were estrogen receptor (ER)-positive breast cancer cell lines (median IC₅₀ > 1000 nM, range 40 to >1000 nM; P = 0.017). In multiple TNBC cell lines, selinexor was synergistic with paclitaxel, carboplatin, eribulin, and doxorubicin in vitro. Selinexor as a single agent reduced tumor growth in vivo in four of five different TNBC PDX models, with a median tumor growth inhibition ratio (T/C: treatment/control) of 42% (range 31 to 73%) and demonstrated greater antitumor efficacy in combination with paclitaxel or eribulin (average T/C ratios of 27% and 12%, respectively).

CONCLUSIONS

Collectively, these findings strongly suggest that selinexor is a promising therapeutic agent for TNBC as a single agent and in combination with standard chemotherapy.

Abstract 3075: Nuclear export inhibitor selinexor (KPT-330) demonstrates anti-tumor efficacy alone and in combination with chemotherapy in multiple breast cancer models

Background: The nuclear exporter XPO1 (Exportin1 or CRM1), mediates the transport of over 200 proteins, including several tumor suppressors. For this reason, XPO1 is being pursued as a promising target for cancer therapy options. Selinexor (KPT-330), a selective inhibitor of nuclear export, is an oral agent that has been shown to inhibit XPO1 and is currently in phase 2 trials for hematologic and solid tumors. We sought to determine the antitumor effect of selinexor in breast cancer cells in vitro and in vivo

Methods: We studied the effects of selinexor in vitro using cell proliferation assays; the half maximal inhibitory concentration (IC50) was calculated using isobologram curves after 3 days of treatment. We also tested the effects in combination with chemotherapy and calculated the combination index by the method of Chou and Talalay. In vivo efficacy was tested in triple negative breast cancer (TNBC) patient derived xenografts (PDXs) with varying levels of paclitaxel sensitivity, as single agent and in combination therapy. T/C ratio was calculated using the formula: [(median tumor volume of treated group)/(median tumor volume of control group) x 100]

Results: Selinexor treatment inhibited growth of 12 breast cancer cell lines representing different subtypes (TNBC as well as ER+, HER+) with a median IC50 of 375nM (range 3-750nM). Selinexor significantly reduced tumor growth in vivo in 4 of 5 different TNBC PDX models (with varying status of TP53 and PIK3CA, and gene expression subtypes), with a median T/C score of 48% (range 34-59%) In Multiple TNBC cell lines, selinexor was synergistic with paclitaxel, carboplatin, eribulin and doxorubicin in vitro. In vivo, selinexor in combination with paclitaxel or eribulin had greater antitumor efficacy than either agent alone.

Conclusions: Collectively these findings strongly suggest that selinexor is a promising therapeutic option for breast cancer.

Citation Format: Natalia Paez Arango, Kurt Evans, Ming Zhao, Erkan Yuca, Stephen Scott, Charissa Kim, Aung Naing, Funda Meric-Bernstam. Nuclear export inhibitor selinexor (KPT-330) demonstrates anti-tumor efficacy alone and in combination with chemotherapy in multiple breast cancer models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3075.