Tolaney, SM

Abstract Background: In CALGB 40601 (Alliance, NCT00770809), a neoadjuvant phase III trial of paclitaxel and trastuzumab with or without lapatinib for 12 weeks for patients with HER2-positive breast cancer, 33% of pretreatment tumors were Luminal A subtype, however, 69% of post-treatment samples with residual disease were Luminal A subtype. In addition, 71% of Luminal B (12/17) and 67% of HER2-Enriched (6/9) tumors changed into Luminal A, while 80% of Luminal A (20/24) remained Luminal A (Carey et al. J Clin Oncol. 2016). It is not known whether this shift to Luminal A was transient or permanent. Methods: We selected matched pairs of pre- and post-treatment 40601 samples with tumor purity >10% based upon DNA analyses to ensure all samples contained tumor. PAM50 intrinsic subtyping was applied to the 40601 samples gene expression data using a two-step normalization process based on The Genome Cancer Atlas, and PAM50 training set. In addition, a HER2-enriched expression subtype patient-derived xenograft (PDX) tumor called WHIM35, was studied and was either untreated (n=10), or treated with lapatinib at 220 mg/kg for 1 week (wk) (n=5), for 2 wks (n=8), or for 3 wks (n=4). We also treated WHIM35 tumors with lapatinib for 2 wks (on) and then removed laptinib for 1 wk (off) (n=6), or for 2 wks on and 2-4 wk off (n=6), and finally for 3 wks on, and 1 wk off (n=3). PAM50 intrinsic subtyping was applied to the PDX gene expression data and subtype assessed as well as a genomic-based proliferation score. ANOVA p-values were calculated by comparing median values across all gene signature or correlation scores. Results: We found 10 pairs of 40601 samples that kept their tumor purity values, however, their subtype changed to Luminal A after treatment (i.e., in the residual disease), and in these cases no minor tumor subclone became a dominant clone in the post treatment sample. Pretreatment subtypes were 6 Luminal B, 3 Luminal A, and 1 HER2-enriched. The tumor purity values did not change after the treatments, but correlation to Luminal A was significantly higher (p=0.01), while correlation to HER2-enriched (p=0.004) and proliferation signature scores (p=0.003) were significantly lower in the post-treatment samples. Among the WHIM35 PDX tumors, one sample changed its subtype from HER2-enriched to Luminal A after the lapatinib treatment and the rest remained HER2-enriched, suggesting environmental differences between patient samples and the PDX model. However, correlation to Luminal A was significantly higher in all lapatinib treated WHIM35 samples (p=8.3e-12), and notably went back to the initial low levels just one week after removing lapatinib. Likewise, correlation to HER2-enriched (p=1.2e-10) and proliferation signature scores (p=6.2e-12) also got lower while treated with lapatinib, but went back to the initial levels after cessation of treatment. Conclusions: Our findings suggest that the apparent subtype change during HER2-targeting therapy is not permanent, but is more likely a transient state change from a HER2-enriched subtype into a more Luminal A-like state. When we plan additional treatment strategies using residual disease phenotypes, it may not be clear what is the true subtype of the sample due to this inherent plasticity. Citation Format: Tanioka M, Parker JS, Henry LN, Tolaney S, Dang C, Krop IE, Harris L, Polley M, Berry DA, Winer EP, Carey LA, Perou CM. Transient state change, but not permanent subtype change, after HER2-targeted therapy for HER2-positive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-08-04.

Abstract Background: PARP inhibitor (PARPi) monotherapy has previously demonstrated clinical activity only in patients with a germline BRCA mutation (BRCAmut), while single-agent anti-programmed cell death protein 1 (PD-1) therapy has achieved response rates of only 5–20% in advanced triple negative breast cancer (TNBC). In preclinical studies, PARP inhibition enhanced anti-tumor immunity, increased infiltration of proliferating CD8+ T cells, and synergized with anti-PD-1 agents in BRCA wildtype (wt) tumors. TOPACIO is a fully enrolled, phase I/II trial of niraparib + pembrolizumab (pembro) in advanced TNBC. This combination achieved 28% objective response rate (ORR) and 50% disease control rate (DCR) in evaluable patients. Although activity was highest in patients with BRCAmut (ORR=60%; DCR=80%), durable clinical benefit was also observed in patients without BRCA mutations. In this study, we conducted exploratory biomarker analyses to evaluate their potential correlation with durable clinical benefit (any complete response [CR] or partial response [PR] regardless of duration or stable disease [SD] for ≥16 weeks) beyond BRCA mutations. Method: ORR was assessed by RECIST v1.1. Duration of disease control (DDC) was defined as time from first dose of study treatment to radiologic disease progression or death. Tumor mutational status of homologous recombination repair (HRR) and other DNA damage repair (DDR) pathway genes was determined using an NGS panel. Immunoprofiling was conducted using NanoString IO360 panel complimented with 30 DNA repair spike-ins. Tumor immune micro-environment was characterized using multiplex immuno-fluorescence (CycIF). PD-L1 status was determined using the Agilent/DAKO 22C3 IHC clinical trial assay. Results: Of 46 evaluable patients, 20 achieved durable clinical benefit (any CR/PR or SD≥16 weeks) with niraparib + pembro combination, of which 8 were tumor BRCA wild type (wt), and 1 was BRCA unknown. Of the 9 BRCAwt/unknown patients, 5 had deleterious mutations in HRR/DDR pathway genes, whereas the remaining 4 had no mutations (HRR/DDR wt). Mutations that were associated with response include CHEK1 (CR; DDC=10.3 mos), ATR (CR; DDC=6.4 mos), PALB2 (PR; DDC=3.5 mos), BLM (SD; DDC=8.1 mos), and NBN/RAD51C (SD; DDC=3.7 mos). Of 4 patients that had no identified mutations (HRR/DDR wt), 1 patient had CR; DDC=10.3 mos, and the remaining 3 patients had SD with DDC ranging from ∼4-8 mos. Of note, all 4 HRR/DDR wt patients were also PD-L1-negative. Table:Durable clinical benefit in BRCAwt/unknown patientsHRR/DRR MutationsPD-L1 StatusBest ResponseDDC (Months)CHEK1+CR10.3†ATR+CR6.4PALB2*UnknownPR3.5BLM-SD8.1NBN/RAD51C+SD3.7None-CR10.3†None-SD8.2None-SD4.2None-SD3.9*BRCA status unknown; †Treatment is ongoing. Conclusion: Patients with mutations beyond BRCA achieved durable clinical benefit with niraparib + pembro treatment; five of these patients had DDC >6 mos. Mutations in genes that are associated with the HRR/DDR pathway appear to confer sensitivity to niraparib + anti-PD1. Additional translational analyses, including immunoprofiling and CycIF, will be presented. Funding: TESARO, Inc., Waltham, MA, USA sponsored the study. Citation Format: Vinayak S, Tolaney SM, Schwartzberg L, Mita M, McCann G, Tan AR, Wahner Hendrickson A, Forero A, Anders C, Wulf G, Dillon P, Lynce F, Zarwan C, Erban J, Färkkilä A, Zhou Y, Buerstatte N, Graham JR, Arora S, Dezube B, Telli ML. Durability of clinical benefit with niraparib + pembrolizumab in patients with advanced triple-negative breast cancer beyond BRCA: (TOPACIO/Keynote-162) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD5-02.

Abstract Purpose Dual HER2 targeting increases pathologic complete response (pCR) rate to neoadjuvant therapy and improves outcomes in both early and metastatic HER2-positive disease. CALGB 40601 is a randomized phase III trial examining the impact of dual HER2 blockade consisting of trastuzumab (H) and lapatinib (L) added to paclitaxel (T) on pCR, considering tumor and microenvironment molecular features. We previously found that pCR was numerically but not significantly increased with dual therapy, and that tumor molecular subtype and evidence of immune activation significantly and independently affected pCR (Carey et al, JCO 2016). In this secondary analysis, we sought to evaluate the effects of treatment arm and gene expression-defined subgroups on invasive disease free survival (IDFS). Patients and Methods Patients (Pts) with stage II to III HER2-positive breast cancer underwent tumor biopsy followed by random assignment with equal probabilityto paclitaxel plus trastuzumab alone (TH) or with the addition of lapatinib (THL) for 16 weeks before surgery. A paclitaxel plus lapatinib (TL) arm was closed early based on reports of futility from other trials. A secondary endpoint was IDFS, defined as the time from surgery until local or distant recurrence, new primary, or death from any cause, whichever was first. Gene expression signatures were identified by RNA sequencing. Results Between 12/2008 and 2/2012, 305 pts were enrolled. 261 pts had IDFS and gene expression information available (THL, n = 103; TH, n =101; TL, n = 57); there were no significant differences in clinical characteristics between this subset and the entire population. The median IDFS follow-up was 4.6 years with 40 IDFS events having occurred (THL, n=7; TH, n=19; TL, n=14). IDFS was significantly longer in the THL arm compared to standard TH (HR=0.34; 95% CI: 0.14-0.82; p=0.02). IDFS was also significantly longer among pCR than non-pCR pts (HR=0.40; 95% CI: 0.19-0.81; p=0.01), and did not differ by hormone receptor (HR) status, clinical stage, tumor size, race, menopausal status or age. Among gene expression signatures, only immune activation measured by an IgG signature was associated with longer IDFS (HR=0.71; 95% CI: 0.51-0.98; p=0.04); this signature was previously also associated with pCR. Multivariate analysis showed dual therapy (HR=0.35; p=0.02), pCR (HR=0.36; p=0.01), IgG (HR=0.69; p=0.05), and molecular subtype (LumA vs HER2E, HR=0.24, p=0.005) were associated with longer IDFS. A subgroup analysis by hormone receptor status revealed that among pts with HR+ disease, pts with luminal A experienced longer IDFS (HR=0.23; p=0.02) compared to those with luminal B or HER2-enriched molecular subtypes. Conclusion Dual HER2-targeting with lapatinib added to 16 weeks of TH produced significantly longer IDFS than TH alone, despite modest effects on pCR. Similar to pts with HER2-negative disease, pts with luminal A had better IDFS than those with other molecular subtypes. Immune activation as measured by RNA-based signature independently predicted both pCR and IDFS. Support: U10CA180882, U10CA180821, U24CA196171, P50-CA58823, Susan G Komen, BCRF Citation Format: Krop IE, Hillman D, Polley M-Y, Tanioka M, Parker J, Huebner L, Henry NL, Tolaney SM, Dang C, Harris L, Berry DA, Perou CM, Partridge A, Winer EP, Carey LA. Invasive disease-free survival and gene expression signatures in CALGB (Alliance) 40601, a randomized phase III neoadjuvant trial of dual HER2-targeting with lapatinib added to chemotherapy plus trastuzumab [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 GS3-02.

Abstract Background: Abemaciclib, a small molecule inhibitor of CDK4 and CDK6, induces G1 cell cycle arrest in Rb-proficient human cancers.1 The clinical safety profile of abemaciclib enables continuous oral dosing to achieve sustained target inhibition, resulting in single-agent antitumor activity against multiple human cancers. The drug also reaches relevant concentrations in the central nervous system and, in patients taking the drug orally, can be detected in the cerebrospinal fluid.2 For women with previously treated hormone receptor positive (HR+) metastatic breast cancer (MBC), abemaciclib as a single agent achieved a six-month clinical benefit rate of 61.1% and an objective response rate of 33.3%.3 Clinical trials investigating abemaciclib combined with fulvestrant4 or aromatase inhibitors5 have led to randomized Phase 3 studies for women with HR+ breast cancer.6,7 Methods: This Phase 1b study (NCT02057133) with multiple cohorts evaluates safety and tolerability of abemaciclib combined with endocrine or HER2-targeted therapies for MBC. Secondary objectives include pharmacokinetics (PK) and antitumor activity of abemaciclib when given in combination with other therapies. Cohorts were opened to enrollment sequentially. Patients with HR+ HER2 negative MBC received abemaciclib orally every 12 hours (Q12H) in combination with the following standard therapies daily until progression: letrozole (Part A), anastrozole (Part B), tamoxifen (Part C), exemestane (Part D), or exemestane plus everolimus (Part E). Patients with HER2 positive MBC received abemaciclib orally Q12H in combination with trastuzumab every 21 days until progression (Part F). Adverse events (AEs) were graded by NCI CTCAE v4.0 and tumor response was assessed radiographically using RECIST v1.1. Results: Abemaciclib has been combined with multiple targeted therapies for the treatment of women with MBC. We previously reported safety and early efficacy results for the combinations of abemaciclib with letrozole, anastrozole, tamoxifen, exemestane, and exemestane plus everolimus.5 Due to limited follow-up at that time, the efficacy results were not mature. Safety, PK, and efficacy results with approximately 6 months of additional follow-up will be reported across all parts of the study. The most common treatment-emergent AEs include effects on the gastrointestinal and hematopoietic systems. Consistent with previously reported results for both single-agent abemaciclib and the combination of abemaciclib with fulvestrant, tumor responses have been observed among women receiving abemaciclib in combination with targeted therapies for MBC. Conclusions: This study for women with MBC demonstrates the potential for abemaciclib to be combined with therapies targeting specific signaling pathways. References: 1Gelbert et al. Invest New Drugs. 2014;32(5):825-37. 2Shapiro et al. J Clin Oncol 31, 2013 (suppl; abstr 2500). 3Tolaney et al. SABCS 2014: Abstract 763. 4Patnaik et al. J Clin Oncol 32:5s, 2014 (suppl; abstr 534). 5Tolaney et al. J Clin Oncol 33, 2015 (suppl; abstr 522). 6Llombart et al. SABCS 2014: OT1-1-07 (MONARCH 2, NCT02107703). 7Goetz et al. J Clin Oncol 33, 2015 (suppl; abstr TPS624) (MONARCH 3, NCT02246621). Citation Format: Goetz MP, Beeram M, Beck T, Conlin AK, Dees EC, Dickler MN, Helsten TL, Conkling PR, Edenfield WJ, Richards DA, Turner PK, Cai N, Chan EM, Pant S, Becerra CH, Kalinsky K, Puhalla SL, Rexer BN, Burris HA, Tolaney SM. Abemaciclib, an inhibitor of CDK4 and CDK6, combined with endocrine and HER2-targeted therapies for women with metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-13-25.

Abstract Background: Imaging biomarkers of cellular division offer promise as non-invasive measures of tumor response. 3’-deoxy-3’[18F]-fluorothymidine ([18F]-FLT) positron emission tomography (PET) imaging generally correlates with pathology-based measurements of cancer proliferation, especially the Ki67 score. Though clinical studies have associated changes in [18F]-FLT uptake with therapeutic response, clinical studies validating its ability to assess cell proliferation are comparatively lacking. The goal of this study was to determine quantitative relationships between [18F]-FLT compared with molecular and cellular metrics of proliferation during treatment for locally advanced breast cancer (LABC). Methods: Baseline [18F]−FLT-PET scans were obtained prior to the initiation of chemotherapy for LABC from patients enrolled at several academic oncology study sites. MRI scans, and transmission CT scans were obtained. Core needle biopsies were obtained to determine Ki-67 indices using immuno-histochemistry and to assess an mRNA signature based measurement of proliferation. Prospectively specified quantitative relationships between PET, Ki67 immunohistochemistry and the mRNA signature were evaluated using image-matched tumor specimens. Correlations between volumetric MRI changes and pathologic responses were evaluated in a post-hoc exploratory analysis. Results: Motivated by the hypothesis that effective chemotherapies should decrease tumor cell proliferation, FLT-PET was compared with biomarkers of proliferation including Ki67 and the mRNA signature during neoadjuvant treatment for LABC. [18F]-FLT correlated both with the Ki67 labeling index (SUVmean r = 0.53) and with the proliferation signature (SUVmean r = 0.7), validating the principle of thymidine analogue imaging. However, variability in the [18F]-FLT PET and tumor cell proliferation measures likely contributed to correlations less than pre-specified target values considered appropriate for clinical use (r > 0.78). Moreover, none of the proliferation biomarkers predicted pathologic complete responses at the end of neoadjuvant therapy ∼16 weeks after the 3 week response scan. In contrast, an evaluation of change in tumor volume measured by MRI after 3 weeks of therapy confirmed its superior ability to predict pCR and tumor re-staging. Conclusion: With large numbers of cancer drugs entering therapeutic pipelines, early efficacy measures remain critical for drug development. The 3-4 month neoadjuvant treatment paradigm for LABC offers unique opportunities for drug evaluation. Functional imaging using [18F]-FLT has been advanced as an assessor of cellular proliferation, potentially offering a non-invasive approach to response evaluation. While [18F]-FLT generally correlated with proliferation, its lack of association with patient responses likely limit its clinical utility. On the other hand, the predictive value of MRI offers unique opportunities for future trial designs and confirms previous reports (1). 1. N. M. Hylton et al., Locally advanced breast cancer: MR imaging for prediction of response to neoadjuvant chemotherapy. Radiology 263, 663 (2012). Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-01-11.