Abstract OT2-07-01: Phase 1/2 trial of the oncolytic virus, talimogene laherparpvec, in combination with neoadjuvant chemotherapy in stage II/III triple negative breast cancer

Background: The host anti-tumor immune response plays an important role in determining natural history and therapy response for early stage breast cancer. Tumors with high levels of lymphocytic infiltration appear to have a superior prognosis and response rate to neoadjuvant chemotherapy. However, these tumors are in the minority so methods to enhance tumor lymphocyte infiltration should be identified. The oncolytic virus, talimogene laherparpvec (TVEC) is a genetically modified HSV1 virus which selectively replicates in transformed cells while sparing normal tissue. This leads to lysis of infected tumor cells along with co-expression of GM-CSF to elicit an enhanced anti-tumor immune response. Prior data has shown TVEC can be safely combined with chemotherapy in other indications, so we launched an investigator initiated study to determine the safety and efficacy of combining TVEC with neoadjuvant dose dense chemotherapy in stage II-III TNBC.

Study design: The study is a phase 1 (2 dose levels of TVEC, 3+3 design) and phase 2 single arm Simon two stage combination trial. Primary endpoints of phase 1 is safety of intratumoral TVEC (DL1=106 PFU x 5 injections, DL2=106 PFU x 1 then 108 PFU x 4 injections) administered q2-3 weeks concurrently with weekly paclitaxel followed by standard dose dense AC x 4 and local therapy as indicated. Phase 2 primary endpoint is pCR rate of the study treatment, secondary endpoints include DFS, OS, immune correlates in resected tumor specimens. Eligibility criteria includes females >17 years old, newly diagnosed T2-3N0-3 TNBC, adequate organ function, primary tumor amenable to injection with TVEC, no immunosuppressive or autoimmune conditions, no inflammatory or bilateral/multifocal disease. Sample size is up to 49 patients (12 phase 1, 37 phase 2) with 80% power to detect increase in pCR rate from 30% to 50% with one sided p=.1 in phase 2.

Study status: This novel Amgen supported investigator initiated study activated to accrual 3/2017 and first patient on study was on 5/2017. The study is currently open only at the Moffitt Cancer Center. Target study completion date 8/2021. (NCT02779855)

Citation Format: Soliman HH, Hogue D, Han H, Lee C, Ismail-Khan R, Khong H, Niell B, Czerniecki B. Phase 1/2 trial of the oncolytic virus, talimogene laherparpvec, in combination with neoadjuvant chemotherapy in stage II/III triple negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT2-07-01.

Abstract OT1-4-04: A phase II randomized, open-label, neoadjuvant study of LCL161, an oral antagonist of inhibitor of apoptosis proteins, in combination with paclitaxel in patients with triple-negative breast cancer

Background: Inhibitor of apoptosis proteins (IAPs) negatively regulate cell death through a variety of mechanisms. LCL161 is an oral small-molecule antagonist of IAPs that has demonstrated single-agent activity and synergy with paclitaxel in breast cancer tumor models. In preclinical studies, a gene expression signature has been shown to enrich for response to LCL161. The recommended dose of LCL161 1800 mg once weekly has demonstrated preliminary antitumor activity with paclitaxel in an ongoing Phase Ib study in patients with breast cancer.

Trial design: This is a Phase II, randomized, open-label study of neoadjuvant paclitaxel with or without LCL161 in women with operable, newly diagnosed triple-negative breast cancer (NCT01617668). Key inclusion criteria include women with histologically confirmed diagnosis of triple-negative breast cancer; clinical stages T2, N0–N2, M0; candidates for mastectomy or breast-conserving surgery; ECOG performance status ≤1; known status of the LCL161-predictive gene expression signature (positive and negative gene signature is a stratification factor); and adequate bone marrow and organ function. Key exclusion criteria are: bilateral or inflammatory breast cancer; locally recurrent breast cancer; patients currently receiving systemic therapy for any other malignancy, or having received systemic therapy for a malignancy in the preceding 3 months; impaired gastrointestinal function that may affect the absorption of LCL161; or uncontrolled cardiac disease.

Patients are randomized 1:1 to receive paclitaxel IV (80 mg/m2 weekly) with or without oral LCL161 (1800 mg once weekly) for 12 weeks (corresponding to 4 treatment cycles). Each treatment arm is stratified 1:1 based on gene expression signature status (positive or negative).

Endpoints: The primary endpoint is pathologic complete response (pCR), defined as the absence of invasive disease in the breast after 12 weeks of therapy, analyzed separately in the gene expression signature positive and negative groups. The key secondary endpoint is the pCR rate following treatment with LCL161 and paclitaxel in gene expression signature-positive or -negative tumors. Other secondary endpoints include: pCR rate in breast after 12 weeks of therapy in the full study population, and in patients with gene expression signature-positive and -negative tumors treated with paclitaxel alone; pCR rate in breast, regional nodes and axilla; biomarker evaluation including caspase 3 activation in tumor; safety; and pharmacokinetics of LCL161.

Statistical methods: pCR analysis will be performed according to treatment group and gene expression signature status. An absolute increase of at least 7.5% in pCR rate of the experimental arm over the control arm will be considered as evidence of clinically relevant efficacy.

Target accrual: Approximately 200 patients will be randomized into this study. Recruitment is ongoing across America, Europe, and Asia.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT1-4-04.

Results of ENCORE 301, a randomized, phase II, double-blind, placebo-controlled study of exemestane with or without entinostat in postmenopausal women with locally recurrent or metastatic estrogen receptor-positive (ER+) breast cancer progressing on a nonsteroidal aromatase inhibitor (AI)

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Background: Hormonal therapy, including AIs, is the mainstay of ER+ breast cancer (BC) treatment; however, both acquired and intrinsic resistance limits its clinical benefit. Entinostat is a novel, oral, class I selective histone deacetylase inhibitor that has been shown to inhibit growth factor signaling pathways that mediate AI resistance. This study was designed to evaluate the impact of the addition of entinostat to exemestane therapy on progression-free survival (PFS).

Methods: Postmenopausal women with ER+ advanced BC who had progressed on a non-steroidal AI were randomized to exemestane 25 mg daily + entinostat 5 mg or placebo weekly.

Results: A total of 130 women were enrolled (66 exemestane+placebo; 64 exemestane+entinostat). All but 1 patient had Stage IV disease, and 82% had measurable disease. All patients had received prior hormonal therapy (1 prior line 42%; >1 prior line 58%), and 62% had received prior chemotherapy (33% in the advanced BC setting). Analysis of the intent-to-treat population showed that PFS was significantly (defined prospectively as p <0.10) longer with exemestane+entinostat than with exemestane+placebo (4.28 versus 2.27 months, respectively; hazard ratio [HR] = 0.73; p=0.06). Entinostat combined with exemestane was well-tolerated with the most frequent adverse events (AEs) consisting of fatigue, gastrointestinal disturbances, and hematologic abnormalities. AEs with a ≥20% higher incidence with exemestane+entinostat than with exemestane+placebo were fatigue (46% versus 26%, respectively) and uncomplicated neutropenia (25% versus 0%, respectively). The serious AE rate was similar for exemestane+entinostat (13%) and exemestane+placebo (12%).

Conclusions: Exemestane+entinostat significantly prolonged the median PFS and reduced the risk of disease progression by 27% versus exemestane+placebo (HR = 0.73). In light of these positive data, a phase III evaluation of this combination is planned.

Clinical Phase II Study of Vorinostat, a Hydroxamic Type Histone Deacetylase Inhibitor, in Combination with Tamoxifen To Reverse Acquired Hormone Resistance in Breast Cancer Patients Who Progressed on Hormone Therapy

Background: Primary or acquired resistance to hormonal therapy remains a major clinical challenge in patients with breast cancer. The most commonly used approach to modulate estrogen receptor signaling includes the use of a selective estrogen receptor modulator or down-regulator, or an aromatase inhibitor. Recently, inhibition of histone deacetylases (HDAC) has emerged as a novel strategy to modulate the estrogen and progesterone receptors by a different mechanism. This study seeks to test whether the addition of an HDAC inhibitor to tamoxifen may reverse acquired hormone resistance.Methods: Patients with estrogen receptor (ER) positive metastatic breast cancer who progressed on prior hormonal therapy with one or two aromatase inhibitors, and up to three chemotherapy regimens for metastatic cancer were treated with 400 mg vorinostat daily for 21 of 28 days and 20 mg tamoxifen daily, continuously. Patients previously treated with tamoxifen in the adjuvant, but not in the metastatic setting, were eligible. Bone only disease was permissible if at least one lesion measured 1 cm by MRI.Results: The study enrolled 43 female patients with a median age of 56 years (range 34-71). To date 42 patients with ER-positive breast cancer completed at least 1 cycle of therapy with a median number of 4 (1-24) cycles and a median duration of response of 8 months. Prior hormonal therapy included at least one aromatase inhibitor in 41 (98%) patients and two aromatase inhibitors in 22 (52%) of the patients; 21 (50%) of the patients received at least one chemotherapy regimen for metastatic disease, and 22 (52%) patients had received adjuvant tamoxifen. Of the 34 patients evaluable for response to date, 7 (21%) had a confirmed partial response and one additional patient with bone only disease had a response by PET/CT, another 4 (12%) patients had stable disease for ≥ 6 months. Dose reductions from 400 mg to 300 mg vorinostat were required in 30% of patients and to 200 mg in 18%. Major grade 3/4 toxicities included fatigue (5 pts, 12%), anorexia/weight loss (2 pts, 5%), nausea/vomiting (2 pts, 5%), hypokalemia (1 pt, 2%), liver enzyme elevations (1 pt, 2%), lymphopenia (7 pts, 16%), thrombocytopenia (3 pts, 7%) and neutropenia (6 pts, 14%). Pulmonary emboli were observed in 2 (5%) patients. Common grade 2 toxicities were fatigue (14%), nausea/vomiting/diarrhea (21%), hyperglycemia (19%), anorexia (12%), and myelosuppression (19%). Histone H3 and H4 acetylation was seen at day 8 suggesting adequate vorinostat plasma levels in the majority of patients.Conclusions: These findings suggest that the addition of the HDAC inhibitor, vorinostat to tamoxifen in patients who have progressed on prior hormonal therapy and including prior adjuvant tamoxifen is tolerable and demonstrates efficacy.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6100.

Phase II trial of the histone deacetylase inhibitor, vorinostat, to restore hormone sensitivity to the antiestrogen tamoxifen in patients with advanced breast cancer who progressed on prior hormone therapy

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Background: Modulation of estrogen receptor signaling is one of the most successful modalities in the treatment of estrogen receptor (ER) positive breast cancers. However, hormone therapy resistance remains a challenging problem. Histone deacetylases (HDAC) have emerged as a recent strategy to interfere with hormone receptor signaling by modulating the estrogen and progesterone receptor. Here we report the findings from a phase II trial evaluating the HDAC inhibitor, vorinostat and the anti-estrogen, tamoxifen, placed in context with correlative studies. Methods: Patients with ER-positive metastatic breast cancer who progressed on prior hormonal therapy and up to three chemotherapy regimens were treated with 400 mg vorinostat daily for three of four weeks and 20 mg tamoxifen daily, continuously. Histone acetylation was evaluated in peripheral blood mononuclear cells. Results: To date, 29 patients [median age 53 years (34–71)] have been treated with the combination. Pulmonary emboli were observed in 2/29 (7%) patients. Other grade 3/4 toxicities included fatigue (5/29, 17%), anorexia (2/29, 7%), diarrhea (1/29, 3%), nausea/vomiting (3/29, 10%), hypokalemia (1/29, 3%), liver enzyme elevation (1/29, 3%), lymphopenia (5/29, 17%) and leukopenia (4/29, 13%). Predominant grade 2 toxicities included fatigue, nausea/vomiting/diarrhea, hyperglycemia, anorexia, and myelosuppression. Six (21%) patients had an objective response, and 3/29 (10%) additional patients had disease stabilization for >6 months; 13/29 (45%) patients had at least one prior chemotherapy regimen for metastatic disease, 28/29 (92%) patients had progressed after exposure to at least one and 16/29 (55%) patients after two aromatase inhibitors, and 18/29 (62%) patients had received prior adjuvant tamoxifen. H3 and H4 histone acetylation was seen at day 8 suggesting adequate vorinostat plasma levels. Histone acetylation and baseline HDAC expression will be presented. Conclusions: These findings suggest that the addition of an HDAC inhibitor to tamoxifen in patients who have progressed on prior hormonal therapy and/or adjuvant tamoxifen may restore hormone sensitivity.

No significant financial relationships to disclose.