NE Oncology Issue – April 2013

Gianni L, et al. SABCS 2012:S6-7

Background

Trastuzumab and pertuzumab have been shown to work by inhibiting the intracellular signalling linked to human epidermal growth factor receptor 2 (HER2) activation and cytotoxic immune mechanisms, including Fc-dependent immune cell activation. HER2-positive breast cancers that are estrogen receptor (ER)-positive or ER-negative are considered molecularly distinct entities. However, regardless of the ER status, immune gene signatures are prognostic and predictive of chemotherapy response. The gene expression profiles of pretreatment tumour samples were characterized from patients of the NeoSphere trial, which evaluated neoadjuvant pertuzumab, trastuzumab, and docetaxel. At SABCS 2012, Gianni and colleagues presented their findings on the association of preselected adaptive immune functions and key immune regulatory genes with the likelihood of achieving a pathological complete response (pCR) in the NeoSphere study.1

Study design

  • Patients with HER2-positive breast cancer enrolled in the NeoSphere study (N = 417) were randomized to receive one of four neoadjuvant treatments:
    • DH: docetaxel (D) + trastuzumab (H);
    • DHPtz: docetaxel + trastuzumab + pertuzumab (Ptz);
    • HPtz: trastuzumab + pertuzumab;
    • DPtz: docetaxel + pertuzumab
  • The primary end point of this study was pCR in the breast.
  • Tumour samples were collected at diagnosis from 98% of all study patients (N = 407) and messenger ribonucleic acid (mRNA) was extracted from the formalin-fixed, paraffin-embedded core biopsies; ER tumour status was defined by immunohistochemistry.
  • Gene expression profiles were obtained for the whole genome of 367 samples (88% of all patients) using the Affymetrix U133 Plus 2.0 microarray chip.
  • The analyzed samples were evenly distributed among the treatment arms: DH (n = 90), DHPtz (n = 95), HPtz (n = 98), and DPtz (n = 84).
  • In correlating the expression levels of certain genes with pCR in the breast or residual disease, other variables considered were: age (continuous), ER and progesterone receptor (PR) status, clinical nodal status, clinical stage at diagnosis, and the treatment arm.

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Key findings

  • The previously reported pCR rates for this study showed patients in the DHPtz arm had the greatest response and all treatments were more effective for patients with tumours lacking ER and PR than those retaining expression of either hormone receptor. (Figure 1)
  • Once identified by expression analysis, biologically relevant immune-related metagenes, which are defined as consistently correlated genes with similar functions or regulation, were selected for further analysis:
    • Metagenes of specific immune cell subtypes:
      • IgG (i.e., immunoglobulins);
      • CD8 Antigen (CD8A): i.e., CD8/~ natural killer (NK) cells;
      • Major Histocompatibility Complex 2 (MHC2) (i.e., dendritic cells).
    • Metagenes under control of common transcription factors:
      • MHC1 (i.e., Human Leukocyte Antigen (HLA) class I [G, F, A, E]);
      • Interferon-inducible genes (I-IG);
        • [i.e., 2’-5’-oligoadenylate synthetase 1 (OAS1), interferon-induced protein 44 like (IFI44L), myxovirus resistance 1, interferon-inducible protein p78 (MX1), interferon-induced protein with tetratricopeptide repeats 1 (IFIT1), IFIT2]);
      • Signal transducer and activator of transcription 1 (STAT1)- related genes (Guanylate binding protein 1 (GBP1), STAT1, Chemokine C-X-C motif ligand 10 (CXCL10), CXCL11).
  • Some individual genes that are key to immune regulation were also assessed:
    • Programmed cell death protein 1 (PD1), programmed cell death ligand 1 (PDL1), PDL2, cytotoxic T-lymphocyteassociated protein 4 (CTLA4), and interferon gamma (IFNG).
  • ER+ and ER– tumours had differential mRNA expression for: CD8A, IgG, PDL2, PD1, IFNG (overexpressed in ER–), and I-IG (overexpressed in ER+).
  • Positive correlations were observed between the expression levels of most of these biomarkers.
    • Only PD1 levels were inversely correlated with STAT1, interferon, and MHC2.
  • In logistic univariate regression analyses some biomarkers showed moderate association with pCR or residual disease without consistent patterns between treatment arms.
  • However, a multivariate logistic regression model constructed for the selected biomarkers in all patients was able to unmask relationships and identified four genes that correlated with pCR in the breast: (Table 1)
    • Reduced odds of attaining pCR were significantly associated with a high expression of:
      • PDL1 (OR = 0.30 [95% CI: 0.15–0.61], p = 0.0007);
      • MHC1 (OR = 0.25 [95% CI: 0.08–0.80], p = 0.019).
    • Increased odds of attaining pCR were significantly associated with a high expression of:
      • PD1 (OR = 3.14 [95% CI: 1.21–8.12], p = 0.018);
      • STAT1 (OR = 2.23 [95% CI: 1.30–3.81], p = 0.003).
  • In addition, high expression of MHC2 showed a trend towards increased odds of attaining pCR in the breast (OR = 2.01 [95% CI: 0.95–4.26], p = 0.069). (Table 1)
  • In a multivariate analysis involving combined treatment arms (DH + HPtz + DPtz), PDL1 (OR = 0.21, p = 0.0002) and ATPase inhibitory factor 1 (IF-1) (OR = 0.58, p = 0.028)were significantly associated with reduced odds of pCR, while STAT1 (OR = 3.68, p = 0.0001), PD1 (OR = 5.12, p = 0.002), and MHC2 (OR = 2.18, p = 0.012) were significantly associated with increased odds of pCR. (Table 2)
  • ER– status, compared with ER+ status, was also associated with significantly increased odds of pCR in the multivariate analysis of the combined treatment arms (DH + HPtz + DPtz) (OR = 6.32, p = 0.001). (Table 2)
  • A significant interaction was present between the ER status and IFNG, PDL1, and CTLA4 (p = 0.0003, p = 0.025, and p = 0.009 for the interaction term, respectively).
  • In a multivariate analysis of the DHPtz arm, both CTLA4 (OR = 0.03, p = 0.007) and PDL1 (OR = 0.07, p = 0.016) were independently and significantly associated with lower chances of pCR in ER– tumours. (Table 3)
  • Also in the analysis of the DHPtz arm, IFNG was significantly associated with better odds of pCR in ER– tumours (OR = 9.63, p = 0.002) and worse odds of pCR in ER+ tumours (OR = 0.11, p = 0.018). (Table 3)

Key conclusions

  • Adaptive immune mechanisms seem to modulate the benefit from HER2-directed therapies, which supports the growing understanding of the key role of the immune system, on top of signalling inhibition, in contributing to the effectiveness of HER2-targeted antibody therapy.
  • High PDL1 expression was consistently strongly associated with residual disease in all arms and with all treatments.
  • These results provide a rationale for combining HER2-targeted treatments with immune-modulating agents and may allow the prediction of treatment benefit.
  • Confirmation of the involvement of adaptive immune mechanisms in the therapeutic effects of the HER2-directed therapies is ongoing in different trials and with different assays.

Reference: 1. Gianni L, Bianchini G, Valagussa P, et al. Adaptive immune system and immune checkpoints are associated with response to pertuzumab (P) and trastuzumab (H) in the NeoSphere study. SABCS Annual Meeting Abstracts 2012:S6-7.

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Canadian Perspectives

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Jean-Francois Larouche, MD

Dr. Jean-Francois Larouche obtained his medical degree in 2000. Upon graduation, he trained in internal medicine, hematology, and oncology at Laval University, Quebec City. Pursuing his interest in oncology, Dr. Larouche completed a postdoctoral fellowship in 2008 in Lyon, France, on lymphoma management. His interests include lymphomas and clinical research.

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Stephen Couban, MD, FRCPC

Dr. Stephen Couban is a professor of medicine at Dalhousie University and Director of the Blood and Marrow Transplant Program at Capital District Health Authority in Halifax, Nova Scotia. He is Co-Chair of the NCIC CTG Hematology Site Group and is also active with the Canadian Blood and Marrow Transplant Group. Dr. Couban is Vice President of the Canadian Hematology Society and a past-president of the Canadian Blood and Marrow Transplant Group. His research interests have focused on allografting and in particular on exploration of different types of grafts, including GCSF-stimulated allogeneic peripheral blood allografts and GCSF-stimulated bone marrow allografts. He is actively involved in a number of clinical trials for patients with leukemia and lymphoma, as well as those undergoing blood and marrow transplantation.

Investigator Commentary

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Sunil Verma, MD, MSEd, FRCPC

Dr. Sunil Verma is a medical oncologist and the Chair of Breast Medical Oncology at the Sunnybrook Odette Cancer Centre in Toronto, Ontario. He is also an Associate Professor at the University of Toronto. Dr. Verma completed his medical degree and postgraduate training in internal medicine and medical oncology at the University of Alberta. He completed a fellowship in breast cancer at the University of Toronto and a master’s degree in medical education at the University of Southern California. Dr. Verma is internationally recognized for his educational leadership and research in breast and lung cancers. He has led and created numerous innovative educational projects in oncology and won several teaching and mentoring awards. Dr. Verma’s research interests include reducing the toxicity of systemic treatment, developing novel therapies for breast and lung cancers, and medical education. He is the principal investigator for many clinical trials in breast and lung cancers, including an international phase III trial in breast cancer, and has authored or co-authored articles appearing in publications such as the Journal of Clinical Oncology, Cancer, The Oncologist, Lancet Oncology, Lancet, and The New England Journal of Medicine.

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Véronique Leblond, MD

Dr. Véronique Leblond is the Head of the Department of Haematology at Pitié- Salpêtrière Hospital, Paris, France. She has a long-standing research interest in the treatment of chronic lymphocytic leukemia (CLL) and Waldenström’s macroglobulinemia (WM). Dr. Leblond has been the Principal Investigator of several multicentre trials investigating immunological therapies and novel chemotherapies. Currently, she is Chair of the French cooperative groups on CLL and WM, and is a member of the French Society of Haematology and the American Society of Haematology. Dr. Leblond has authored over 250 research articles, books, and book chapters.

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Francesco Lo-Coco, MD

Dr. Francesco Lo-Coco is a full Professor of Hematology and Head of the Laboratory of Integrated Diagnosis of Oncohematologic Diseases at the Department of Biopathology, University of Rome Tor Vergata, Rome, Italy. His main research activities include genetic characterization, monitoring, and treatment of hematologic tumours, particularly acute myeloid leukemia and acute promyelocytic leukemia (APL). He has served as President of the Italian Society of Experimental Hematology, been a board member of the Italian Foundation for Cancer Research, and a member of the Committee on Health Research at the Italian Ministry of Health. He is presently chairman of the APL subcommittee of the Italian National Cooperative Group GIMEMA, chairman of the Education Committee of the European Hematology Association, and a member of the editorial board for the journals Leukemia and Haematologica.