Homoharringtonine, an approved anti-leukemia drug, suppresses triple negative breast cancer growth through a rapid reduction of anti-apoptotic protein abundance

Triple negative breast cancers (TNBC) without BRCA1/2 gene mutation or BRCAness are nowadays the breast malignancies most difficult to treat. Improvement of their treatment, for all phases of the disease, is an important unmet medical need. We analyzed the effect of homoharringtonine (HHT), a natural protein synthesis inhibitor approved for treatment of chronic myeloid leukemia, on four cell lines representing aggressive, BRCA1/2 non-mutated, TNBC genomic categories. We show that HHT inhibits in vitro growth of all cell lines for more than 80%, after 48-72 h exposure to 20-100 ng/mL, the concentrations achievable in human plasma after subcutaneous administration of the drug. HHT, at 100 ng/mL, strongly reduced levels of a major TNBC survival factor, anti-apoptotic protein Mcl-1, after only 2 h of exposure, in all cell lines except MDA-MB-231. Other anti-apoptotic proteins, Bcl-2, survivin and XIAP, were also strongly downregulated. Moreover, in vivo growth of the least sensitive cell line to HHT in vitro, MDA-MB-231, was inhibited for 36.5% in mice, by 1 mg/kg of the drug, given subcutaneously, bi-daily, over 7 days. These results demonstrate marked antineoplastic activity of homoharringtonine in TNBC, making further development of the drug in this disease highly warranted.

An auristatin-based antibody-drug conjugate targeting HER3 enhances the radiation response in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer characterized by poor response to chemotherapy and radiotherapy due to the lack of efficient therapeutic tools and early diagnostic markers. We previously generated the nonligand competing anti-HER3 antibody 9F7-F11 that binds to pancreatic tumor cells and induces tumor regression in vivo in experimental models. Here, we asked whether coupling 9F7-F11 with a radiosensitizer, such as monomethylauristatin E (MMAE), by using the antibody-drug conjugate (ADC) technology could improve radiation therapy efficacy in PDAC. We found that the MMAE-based HER3 antibody-drug conjugate (HER3-ADC) was efficiently internalized in tumor cells, increased the fraction of cells arrested in G2/M, which is the most radiosensitive phase of the cell cycle, and promoted programmed cell death of irradiated HER3-positive pancreatic cancer cells (BxPC3 and HPAC cell lines). HER3-ADC decreased the clonogenic survival of irradiated cells by increasing DNA double-strand break formation (based on γH2AX level), and by modulating DNA damage repair. Tumor radiosensitization with HER3-ADC favored the inhibition of the AKT-induced survival pathway, together with more efficient caspase 3/PARP-mediated apoptosis. Incubation with HER3-ADC before irradiation synergistically reduced the phosphorylation of STAT3, which is involved in chemoradiation resistance. In vivo, the combination of HER3-ADC with radiation therapy increased the overall survival of mice harboring BxPC3, HPAC cell xenografts or patient-derived xenografts, and reduced proliferation (KI67-positive cells). Combining auristatin radiosensitizer delivery via an HER3-ADC with radiotherapy is a new promising therapeutic strategy in PDAC.

Abstract P5-12-09: The ≥5% cut-off reveals tumor PD-L1 positivity as potential selection biomarker for patient enrollment into the trials evaluating anti-PD-1 or anti-PD-L1 agents in neoadjuvant treatment of triple negative breast cancer

Background: Durable responses of triple negative breast cancer (TNBC) to pembrolizumab (anti-PD-1) or atezolizumab (anti-PD-L1) have been reported in the metastatic setting. Moreover, it is currently being hypothesized that immune checkpoint inhibitors might be more effective in the neoadjuvant setting, due to better preserved anti-tumor immunity in early TN disease. However, biomarkers predictive of response to anti-PD-1 or anti-PD-L1 agents, as well as biomarker-based strategies for testing those drugs in the neoadjuvant setting are still lacking. We evaluated PD-L1 protein expression and the composition of tumor-infiltrating lymphocytes (TILs) in untreated TNBC, in order to get a better insight into the TNBC sub-population(s) which would be suitable for neoadjuvant anti-PD-1 or anti-PD-L1 therapy evaluation. Methods: TNBC patients consecutively treated at the Jean Perrin Comprehensive Cancer Centre (Clermont-Ferrand, France), from 01/01/2010 to 12/31/2014, were included. FFPE tumor tissues were assessed for PD-L1 expression by immunohistochemical (IHC) laboratory-developed test (clone 28-8, Abcam), in tumor cells (tPD-L1) and in TILs. Positivity cut-offs evaluated were ≥1%, ≥5% and ≥10%. The amount CD8+, CD4+, FoxP3+ or PD-1+ TILs was determined by counting those cells, detected by IHC methods, within 5 consecutive HPFs (x400), from tumor invasive front toward tumor center. Clinical disease stage was determined using the TNM system. Results: One hundred and two TNBCs were assessed. There were 28.4%, 23.5% or 16.7% tPD-L1-positive cases (cs), for cut-offs ≥1%, ≥5% or ≥10%, respectively. Similarly, 32.4%, 15.7% or 5.9% of cs were positive for PD-L1 in TILs, using the same cut-offs. With ≥5% as cut-off, positivity for tPD-L1 significantly correlated with the amount of CD8+ (p=0.023), FoxP3+ (p=0.0036) or PD-1+ TILs (p=0.043). The same cut-off, applied to TILs, revealed significant correlations between PD-L1 positivity and the amount of each CD8+, CD4+ or PD-1+ TILs (p=0.025, 0.039 and 0.0042, respectively). Interestingly, when the ≥5% cut-off was used, tumors of T2 size were most frequently tPD-L1+ (11/41 cs, 26.8%), compared with the T1 (3/35 cs, 8.6%) and T3+T4 (3/18 cases, 16.7%) (p=0.04). With regards to TILs, with the ≥5% cut-off, the PD-L1+ cases belonged exclusively to the T1+T2 group (15/76), whereas the T3+T4 group was PD-L1-negative (0/18 cs). Other two cut-offs revealed only occasional correlations. Conclusion: This single-center, real-world TNBC cohort contained a high number of smaller tumors (T1-T2). The IHC-based PD-L1 assessment, with ≥5% as the positivity cut-off, revealed that approximately 1/4 of TNBC could be candidates for neoadjuvant anti-PD-1/anti-PD-L1 approaches. Combined with the amount of CD8+ and PD-1+ TILs, tumor PD-L1 positivity might make an easy-to-use composite biomarker for the 1st-level patient selection for PD-1 or PD-L1 inhibitors in neoadjuvant TNBC treatment. The 2nd level could exploit, for example, the assessment of mutation burden in tumors with low tPD-L1 or amount of CD8+ or PD-1+ TILs. Such tumors might be more frequent among larger TNBC (T3-T4).

Citation Format: Finck W, Passildas J, Poirier C, Kwiatkowski F, Abrial C, Durando X, Penault-Llorca F, Radosevic-Robin N. The ≥5% cut-off reveals tumor PD-L1 positivity as potential selection biomarker for patient enrollment into the trials evaluating anti-PD-1 or anti-PD-L1 agents in neoadjuvant treatment of triple negative 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 P5-12-09.

Tumor mutational burden in non-small cell lung cancer-the pathologist's point of view

In non-small cell lung cancer (NSCLC), the pathologist has contributed to the development of personalized medicine from the determination of the right histological type to EGFR and ALK/ROS1 molecular screening for targeted therapies. With the development of immunotherapies, pathologists intervene forefront with programmed death-ligand 1 (PD-L1) immunohistochemical testing, companion test for pembrolizumab monotherapy, first line and complementary test to the other programmed cell death-1 (PD-1) PD-L1 inhibitors. Recently, tumor mutational burden has emerged as a promising tool to evaluate sensitivity to immunotherapy (IO). The pathologist has a crucial role in the setting of tumor mutational burden (TMB) testing for the selection and the preparation of the sample for high throughput molecular analysis, and in the first steps of the next-generation sequencing (NGS) workflow.

Characterisation of gut, lung, and upper airways microbiota in patients with non-small cell lung carcinoma: Study protocol for case-control observational trial

BACKGROUND

Several studies have confirmed the important role of the gut microbiota in the regulation of immune functions and its correlation with different diseases, including cancer. While brain-gut and liver-gut axes have already been demonstrated, the existence of a lung-gut axis has been suggested more recently, with the idea that changes in the gut microbiota could affect the lung microbiota, and vice versa. Likewise, the close connection between gut microbiota and cancer of proximal sites (intestines, kidneys, liver, etc.) is already well established. However, little is known whether there is a similar relation when looking at world's number one cause of death from cancer-lung cancer.

OBJECTIVE

Firstly, this study aims to characterise the gut, lung, and upper airways (UAs) microbiota in patients with non-small cell lung cancer (NSCLC) treated with surgery or neoadjuvant chemotherapy plus surgery. Secondly, it aims to evaluate a chemotherapy effect on site-specific microbiota and its influence on immune profile. To our knowledge, this is the 1st study that will analyse multi-site microbiota in NSCLC patients along with site-specific immune response.

METHODS

The study is a case-controlled observational trial. Forty NSCLC patients will be divided into 2 groups depending on their anamnesis: Pchir, patients eligible for surgery, or Pct-chir, patients eligible for neoadjuvant chemotherapy plus surgery. Composition of the UAs (saliva), gut (faeces), and lung microbiota (from broncho-alveolar lavage fluid (BALF) and 3 lung pieces: "healthy" tissue distal to tumour, peritumoural tissue and tumour itself) will be analysed in both groups. Immune properties will be evaluated on the local (evaluation of the tumour immune cell infiltrate, tumour classification and properties, immune cell phenotyping in BALF; human neutrophil protein (HNP) 1-3, β-defensin 2, and calprotectin in faeces) and systemic level (blood cytokine and immune cell profile). Short-chain fatty acids (SCFAs) (major products of bacterial fermentation with an effect on immune system) will be dosed in faecal samples. Other factors such as nutrition and smoking status will be recorded for each patient. We hypothesise that smoking status and tumour type/grade will be major factors influencing both microbiota and immune/inflammatory profile of all sampling sites. Furthermore, due to non-selectivity, the same effect is expected from chemotherapy.

Abstract 5803: Homoharringtonine, a natural protein synthesis inhibitor, inhibits growth of triple negative breast cancer in vitro and in vivo

Introduction: Triple negative breast cancer (TNBC) is a heterogeneous disease for which new therapeutic approaches are urgently needed. Homoharringtonine (HHT) is a protein synthesis inhibitor clinically approved in chronic myeloid leukemia. Its multi-factor mechanism of action includes downregulation of short-lived cellular proteins like Mcl-1. As increased protein synthesis lies behind several hallmarks of cancer present in TNBC, we investigated the effect of HHT on TNBC in vitro and in vivo.

Methods: TNBC cell lines CAL-51, MDA-MB-231 and MDA-MB-468, representative of aggressive, BRCA1 non-mutated TNBC (Lehmann, J Clin Invest 2011) were used. HHT was provided by LeukePharma, Houston, TX, USA. Cell viability was assessed by sulphorhodamine B assay. Number of cells in different cell cycle phases or in apoptosis was determined by flow cytometry. Protein expression was evaluated by western blot. For in vivo experiments, xenografts of MDA-MB-231 were established in Swiss nu/nu mice, treated for 7 days by subcutaneous HHT (1 mg/kg, bi-daily), and analyzed on day 10. Evaluation of HHT on MDA-MB-468 and CAL-51 xenografts is ongoing.

Results: Already after 24h of exposure to 100 ng/ml HHT (mean plasma HHT concentration after 5 mg/m2/day in humans (Sentenac S et al, Blood 2003)), viability of CAL-51 and MDA-MB-468 cells was strongly reduced (10.4±1.0% and 19.2±2.2% of control, respectively). This inhibition level was obtained in MDA-MB-231 cells only after 72h (18.7±4.8%). After 48h in 100 ng/ml HHT, MDA-MB-231 and -468 cells accumulated in the S phase of the cell cycle, whereas the CAL-51 accumulated in the G1/0 phase. This was associated with an increase of apoptosis in CAL-51 (42.0±2.4% vs 9.2±1.3%, untreated vs treated cells, respectively) and in MDA-MB-468 (24.2±2.8% vs 12.2±3.6%) but not in MDA-MB-231 (9.0±2.2% vs 3.6±1.7%). Concordantly, 100 ng/ml of HHT induced, after only 2h, a marked decrease of the level of anti-apoptotic proteins Mcl-1, Bcl-2, survivin and XIAP in CAL-51 and MDA-MB-468 cells, which preceded by 2h the reduction of caspase-3 level. No change in expression of those proteins was observed in MDA-MB-231 during all 48h of exposure to HHT. On the other side, the quantity of phosphorylated S6 increased in MDA-MB-231 but decreased in CAL-51 and MDA-MB-468 already after 24h of incubation with 100 ng/ml HHT. In vivo, HHT reduced growth of MDA-MB-231 xenografts for 36.5% (tumor volume on day 10: 230.4±27.7% mm3 vs 146.2±15.5% mm3, untreated vs treated, respectively).

Conclusion: HHT exerts cytotoxic action on TNBC cell lines CAL-51 and MDA-MB-468 whereas its effect on MDA-MB-231 is dominantly cytostatic. Because of its capacity to rapidly reduce the levels of anti-apoptotic proteins, HHT is worth further studies as potential sensitizer of TNBC to chemo- and/or targeted therapy.

Citation Format: Mohamad Yakhni, Arnaud Briat, Elisabeth Miot-Noirault, Florent Cachin, Frederique Penault-Llorca, Nina Radosevic-Robin. Homoharringtonine, a natural protein synthesis inhibitor, inhibits growth of triple negative breast cancer in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5803.

Abstract P4-15-03: Tumor-infiltrating lymphocytes in breast ductal carcinoma in situ: Correlations with tumor pathobiology in a French cohort of 495 cases (BONBIS)

Background: Numerous studies have shown important impact of tumor-infiltrating lymphocytes (TILs) on natural or therapeutically-modified evolution of invasive breast cancer (IBC), however knowledge about TIL role in breast ductal carcinoma in situ (DCIS) is still limited. Because of the lack of reliable prognostic parameters, DCIS treatment is much less personalized than IBC therapy. BONBIS is a phase 3 French multicenter randomized trial designed to compare 2 schemes of adjuvant radiotherapy (adjRT) for DCIS (Azria et al, ASCO meeting 2011, TPS 131). It is accompanied by a translational study of DCIS pathobiology, aimed to discover predictive or prognostic biomarkers. Here we present results of TIL density (TIL-d) assessment, its correlation with pathobiology of the lesions and preliminary clues for further biomarker search in this DCIS cohort. Methods: Formalin-fixed, paraffin-embedded DCIS surgical specimens, obtained before adjRT, were prospectively collected and centrally reviewed for histology (architectural pattern, nuclear grade, proliferation, presence of necrosis), receptor status (ER, PR, HER2) and TIL-d. TIL-d was assessed on H&E-stained DCIS sections and reported as percentage of the DCIS specialized stroma area occupied by lymphocytes, lympho-plasmocytes and plasmocytes. Tumors were classified using the St Gallen 2011 criteria for IBC (PMID 21709140). For purpose of this study, the HER2+ category included all cases with HER2 protein expression scored 2+ and 3+, irrespective of the ERBB2 amplification status. Results: TIL-d was assessed in 495 cases, with distribution as follows: 0-4% TILs (D1): 85.5% (n=423); 5-9% TILs (D2): 9.3% (n=46); ≥10% TILs (D3): 5.2% (n=26). Molecular subclasses of those cases were: luminal A (LumA): 39% (n=192); luminal B (LumB): 25.5% (n=126), HER2+: 28.5% (n=141) and triple-negative (TN): 7% (n=33). TIL-d significantly correlated with molecular subclass: ≥5% TILs (D2) were found in 39.4% (13/33) TN, 22.7% (32/141) HER2+, 18.2% (23/126) LumB and only in 1% (2/192) LumA cases (p<10-7). TIL-d of ≥10% (D3) was found only in 26/495 cases (5.2%) and of ≥50% only in one. Similarly to D2, D3 was most frequent in TN, and then in HER2+, LumB and LumA lesions (15%, 9.2%, 7.1%, 0.5%, resp., p<10-7). TIL-d significantly correlated with 2 architectural patterns: positively with solid (38.8%, 52.2% and 60% of D1, D2 and D3 within the solid lesions, resp., p=0.03) but negatively with cribriform (53%, 32.6% and 28% of D1, D2 and D3 within the cribriform lesions, resp., p=0.0027). Finally, the presence of necrosis was significantly associated with TIL-d of ≥5% (65.7% vs 84.5%, D1 vs D2+D3, p=0.071). Due to still short follow-up, the analysis of predictive factors for survival or adjRT benefit was not performed. Conclusion: This DCIS cohort is characterized by low density of TILs. Richer infiltration by TILs (≥10%) was found, as reported in IBC, in TN and HER2+ lesions, however ≥50% TILs was an extremely rare finding. Interestingly, the LumB cases had TIL-d comparable to the HER2+ cases. The associations between ≥10% TILs and molecular subclass or with DCIS architecture will be evaluated in the future as biomarkers of adjRT impact on survival in this cohort.

Citation Format: Bayol B, Tixier-Deves L, Dauplat M, Kwiatkowski F, Cayre A, Abrial C, Azria D, Penault-Llorca F, Radosevic-Robin N. Tumor-infiltrating lymphocytes in breast ductal carcinoma in situ: Correlations with tumor pathobiology in a French cohort of 495 cases (BONBIS) [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 P4-15-03.

Abstract P2-09-29: Potential recurrence markers of locally advanced triple negative breast cancer treated by combined neoadjuvant EGFR targeting and chemotherapy, revealed by genomic analyses and assessment of tumor-infiltrating lymphocytes

Background: Epidermal growth factor receptor (EGFR) is expressed in ˜50% of triple negative breast cancer (TNBC) and has been proposed as a therapeutic target in this disease. However, trials testing EGFR blockade in TNBC failed to show significant clinical benefit. Probable reasons for such results were patient selection based on EGFR expression and the enrollment of heavily pretreated metastatic patients. Our team has conducted two neoadjuvant trials testing the activity of the anti-EGFR antibodies panitumumab (PTB) and cetuximab (CTX) combined with chemotherapy in locally advanced TNBC. Biomarkers predictive of pathological complete response (pCR) were the level of tumor cell EGFR protein expression and tumor-infiltrating lymphocytes' (TILs) profile (PMIDs 24827135, 26649807). The PTB-treated pts had a higher pCR rate (47%) than the CTX-treated pts (24%), but also a twice higher relapse rate, after 5 years of follow-up. Here we report results of genomic and TILs studies, performed in order to reveal possible determinants of recurrences in those trials. Methods: Tumor tissues sampled before and after neoadjuvant therapy (NAT) have been analyzed by next generation sequencing (NGS) using a targeted exome panel (MSK-IMPACT) of 410 cancer-related genes. Gene expression was evaluated by Affymetrix arrays. TIL density was assessed on pre-NAT samples according to Salgado et al, 2014 (PMID 25214542). The correlation between response, recurrences, genomic and TIL findings was analyzed in a case-by-case fashion. Results: Sixteen tumors that achieved pCR (PTB: 11, CTX: 5) and 23 non-pCR tumors (PTB: 11, CTX: 12) have been analyzed. For 14 non-pCR tumors (PTB: 6, CTX: 8) data have been obtained both from the pre-NAT and the post-NAT sample. Among those tumors, 6 recurred within 2 years after surgery (PTMB: 3, CTX: 3) and assays are on-going on several others that relapsed. Several genomic aberrations that potentially played a causative role in opposing to therapy were identified. We observed multiple mutations in the PI3K pathway in several non-pCR or relapsing pts. Interestingly, in a residual tumor (RT) of a non-pCR patient we found 3 different activating mutations in PIK3CA and one in PTEN. Another example of genomic selection induced by pharmacological pressure is the emergence of a HRAS G12S mutation in a RT after CTX. Additional novel findings include in-frame mutations and deletions in ARID1B and PARP1 amplification in non-pCR pts. Most of the tumors which recurred had ≤10% TILs (9/13) and only 4/13 had ≥30%. Among the tumors with a post-NAT RT but without recurrence, 17/33 had ≤10% TILs and 16/33 ≥30%. No particular link between TIL density and mutation pattern was observed. Conclusions: This is an example of a case-by-case approach where we captured the intrinsic inter-tumor heterogeneity, which is likely responsible for the different responses to EGFR-targeting in TNBC. Genes/pathways candidate of resistance to therapy are currently being validated.

Citation Format: Radosevic-Robin N, Cocco E, Privat M, Abrial C, Penault-Llorca F, Scaltriti M. Potential recurrence markers of locally advanced triple negative breast cancer treated by combined neoadjuvant EGFR targeting and chemotherapy, revealed by genomic analyses and assessment of tumor-infiltrating lymphocytes [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 P2-09-29.

Analysis of tumour-infiltrating lymphocytes reveals two new biologically different subgroups of breast ductal carcinoma in situ

Background

Tumour-infiltrating lymphocytes (TILs) have been demonstrated to significantly influence prognosis and response to therapy of invasive breast cancer (IBC). Thus, it has been suggested that TIL density or/and immunophenotype could serve as biomarkers for selection of IBC patients for immunotherapy. However, much less is known about significance of TILs in breast ductal carcinoma in situ (DCIS).

Methods

We retrospectively investigated TIL density and immunophenotype in 96 pure DCIS and 35 microinvasive carcinomas (miCa). TIL density was assessed on H&E-stained breast biopsy sections as the percentage of tumour stromal area occupied by TILs, and classified into 4 grades: 0 (0%–9%), 1 (10–29%), 2 (30–49%) and 3 (50%–100%). TIL immunophenotype was assessed by immunohistochemistry for CD8, CD4, FoxP3, CD38 or CD20.

Results

Compared to pure DCIS, miCa contained significantly more cases with TIL density grade 3 (p = 0.028). Concordantly, CD8+, CD4+ and CD38+ cells were more numerous in miCa than in pure DCIS. In the pure DCIS subgroup with TIL density grades 2 and 3, all TIL subpopulations were more numerous than in the pure DCIS with TIL density grades 0 and 1, however the ratio between T-lymphocytes (CD8+ and CD4+) and B-lymphocytes (CD20+) was significantly lower (p = 0.029). On the other side, this ratio was significantly higher in miCa, in comparison with pure DCIS having TIL density grades 2 and 3 (p = 0.017). By cluster analysis of tumour cell pathobiological features we demonstrated similarity between miCa and the pure DCIS with TIL density grades 2 and 3. The only significant difference between those two categories was in the ratio of T- to B-TILs, higher in miCa.

Conclusion

Results indicate that TIL density level can distinguish 2 biologically different DCIS subgroups, one of which (DCIS with ≥30% TILs, the TIL-rich DCIS) is like miCa. Similarity of TIL-rich pure DCIS and miCa as well as the role of B-lymphocytes in DCIS invasiveness are worth further investigating with regards to the potential development of immunotherapy-based prevention of DCIS progression.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4013-6) contains supplementary material, which is available to authorized users.

Ki67 assessment in breast cancer: an update

Although immunohistochemical detection of the Ki67 antigen has been used for many years to assess cancer proliferation, this marker is still not recommended for routine use in clinical management of breast cancer. The major reason for this situation is a lack of a standardised procedure for Ki67 assessment as well as persistence of several issues of debate with regards to the Ki67 assay interpretation and the marker's clinical utility. Nowadays Ki67 assessment is principally used for estimation of prognosis and guiding the decision on adjuvant treatment choice, as well as for prediction of response to neoadjuvant treatment in ER+/HER2- breast cancer. In ER-/HER2+ and ER-/HER2- tumours, high post-neoadjuvant Ki67 index is associated with unfavourable prognosis. We review here the elements impacting analytical validity of the Ki67 immunohistochemical assay, the evidence of its clinical utility and the current recommendations for its use in breast cancer management.

[Evaluation of the immune infiltrate in breast cancer]

Tumour-infiltrating lymphocytes (TIL) are major components of the immune/"inflammatory" infiltrate found in tumour microenvironment. They reflect the intensity and the quality of the immune reaction to cancer. In breast cancer, TIL density and phenotypic profile have been demonstrated to be predictive of response to neoadjuvant treatment and of patient outcome. TIL density, currently the best-developed TIL-related biomarker, is defined as the percentage of tumour stroma surface occupied by TIL. The baseline TIL density of 50% and higher is associated with particularly high rates of pathological complete response to neoadjuvant therapy in triple negative and HER2+ breast cancer, as well as with significantly better recurrence-free and overall survival. Similar predictive and prognostic value has been demonstrated for the ratio between the numbers of CD8+ and FoxP3+ TIL. TIL density and the CD8+/FoxP3+ ratio are promising biomarkers in breast cancer, which could be used in tailoring of neoadjuvant and adjuvant systemic therapy and in selection of patients for different immunotherapy modalities. This article reviews elements of the immune response to cancer, methods of TIL analysis, evidence of TIL' prognostic and predictive value in the current breast cancer management as well as the perspectives for use of TIL' characteristics as biomarkers in breast cancer immunotherapy.

Daily Practice Management of pT1a-b pN0 Breast Carcinoma: A Prospective French ODISSEE Cohort Study

BACKGROUND

Most breast cancer (BC) tumors ≤10 mm have an excellent prognosis. The subgroups with a higher risk for distant recurrence requiring adjuvant systemic therapy are not precisely defined in current international guidelines.

PATIENTS AND METHODS

The OBSERVATOIRE DES PETITS CANCERS DU SEIN HER2 +/- (ODISSEE) study was a prospective, multicenter, cohort study that aimed to describe the daily adjuvant management and outcome of 616 patients with unifocal, invasive pT1a-b pN0 nonmetastatic BC who underwent surgery.

RESULTS

At the time of diagnosis, the median age of patients was 61 years. Tumor was detected on imaging or during a screening program in 397 patients (64.6%). Most patients (96%) underwent conservative surgery with sentinel node biopsy (89%), completed with axillary lymph node dissection in 15%. At inclusion, 82% of tumors were pT1b, 73% were pN0 (i-), 53% were Scarff-Bloom-Richardson Grade I, 91% were estrogen receptor (ER)-positive, 5% overexpressed/amplified HER2, and 5% were triple negative (TNBC). Adjuvant treatments were radiotherapy (95%), hormone therapy (82%), chemotherapy (7%), and trastuzumab (3.5%). In patients with TNBC and HER2-positive BC, chemotherapy and trastuzumab (if needed) were administered in 45% and 68%, respectively. After 5 years of follow-up, 7 patients had contralateral BC, 7 had locoregional recurrence, and 1 had distant metastasis. At 5 years, overall survival, disease-free survival, and recurrence-free survival were: 98.4% (96.9%-99.1%), 94.7% (92.4%-96.3%), and 97.1% (95.2%-98.2%), respectively.

CONCLUSION

This prospective cohort study showed that in France, the routine practice in pT1a-b pN0 breast cancers follows international standard guidelines for practice including conservative surgery followed by radiotherapy and endocrine therapy for ER-positive patients. Adjuvant chemotherapy with or without trastuzumab was used but their benefit in breast cancer of ≤10 mm remains controversial.

Stratification and therapeutic potential of PML in metastatic breast cancer

Patient stratification has been instrumental for the success of targeted therapies in breast cancer. However, the molecular basis of metastatic breast cancer and its therapeutic vulnerabilities remain poorly understood. Here we show that PML is a novel target in aggressive breast cancer. The acquisition of aggressiveness and metastatic features in breast tumours is accompanied by the elevated PML expression and enhanced sensitivity to its inhibition. Interestingly, we find that STAT3 is responsible, at least in part, for the transcriptional upregulation of PML in breast cancer. Moreover, PML targeting hampers breast cancer initiation and metastatic seeding. Mechanistically, this biological activity relies on the regulation of the stem cell gene SOX9 through interaction of PML with its promoter region. Altogether, we identify a novel pathway sustaining breast cancer aggressiveness that can be therapeutically exploited in combination with PML-based stratification.

Abstract 1465: Analysis of tumor-infiltrating lymphocytes (TILs) reveals biologically different subgroups of breast ductal carcinoma in situ

Background: Treatment of breast ductal carcinoma in situ (DCIS) aims to prevent invasive recurrence. Recent studies have shown an important impact of TILs on the outcome of invasive breast cancer, however their influence on breast DCIS prognosis has not been fully explored. In this study we investigated whether the amount and/or phenotype of TILs can help recognizing DCIS subgroups of different biology and recurrence risk.

Methods: The study included 134 patients, diagnosed and treated for a DCIS from 2001 to 2005 in our institution. Formalin-fixed and paraffin-embedded (FFPE) cancer tissue samples, taken before any treatment, were retrospectively collected. H&E whole tissue sections served for assessment of the cancer size, grade, histotype, architecture, mitotic index and amount of stromal lymphocytic (Ly) infiltrate. The latter was semi-quantitatively graded into 4 grades (0 - absent, 1 - mild, 2 - moderate, 3 - intense). Ly-phenotype was assessed by immunohistochemistry (IHC) on tissue microarrays (TMAs), constructed by sampling each case at the area of the densest Ly-infiltration (3 cores of 0.6 mm diameter per case). The number/mm2 of the CD8+, CD4+, FOXP3+, CD20+ and CD38+ mononuclear cells was determined. TMAs served also for estrogen receptor (ER), progesterone receptor (PR), HER2 and Ki67 IHC staining, as well as for HER2 amplification status.

Results: There were 97 DCIS and 37 microinvasive DCIS (micDCIS). The micDCIS displayed significantly more diffuse architecture, frequent HER2 amplification (HER2amp), higher grade, lower ER expression (0.029<p<0.044 for each) and more peritumoral Ly-infiltrate (grades 2+3, micDCIS vs DCIS, 51.5% vs. 39.0%, p = 0.036). All but CD20+ cells were more numerous in micDCIS than in DCIS (0.0016<p<0.05). Within the entire cohort, the cases having the (CD8+/CD4+):(CD20+/CD38+) ratio higher than 1 had a significantly greater risk of containing a microinvasive component (OR 3.47 (1.26-9.57), p = 0.029). Interestingly, that ratio was significantly higher (p = 0.012) in micDCIS than in the DCIS with grade 2 or 3 Ly-infiltrate (Ly-DCIS, n = 38). On the other side, there was no difference between micDCIS and Ly-DCIS in architecture, histograde, HER2amp rate and ER expression. Cluster analysis further confirmed significant similarities between micDCIS and Ly-DCIS, putting them both apart from non-Ly-DCIS (p = 0.0034).

The overall 10-year recurrence rate was 13% (18/134 pts). No parameter significantly correlated with recurrence risk, however the micDCIS have received significantly more treatment than DCIS (axillary lymphadenectomy (p<10-7), chemotherapy (p = 0.031) or hormonal therapy (p = 5.4×10-6)).

Conclusion: These results indicate that Ly-DCIS might be biologically and immunologically similar to micDCIS. TILs in DCIS are worth investigating in larger studies, as they could be a marker of microinvasion and help tailoring the initial treatment of the disease.

Citation Format: Marie Beguinot-Cornillon, Marie-Melanie Dauplat, Fabrice Kwiatkowski, Guillaume Lebouedec, Lucie Tixier, Christophe Pomel, Frederique Penault-Llorca, Nina Radosevic-Robin. Analysis of tumor-infiltrating lymphocytes (TILs) reveals biologically different subgroups of breast ductal carcinoma in situ. [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 1465.

Combination of mTOR and EGFR targeting in an orthotopic xenograft model of head and neck cancer

OBJECTIVES/HYPOTHESIS

Recent preclinical and clinical studies on head and neck squamous cell carcinoma (HNSCC) revealed synergistic effects when combining anti-EGFR agents with conventional chemotherapeutic drugs. Activation of the PI3-kinase/AKT/mTOR signaling pathway has been identified as an important mechanism implicated in tumor progression and resistance to EGFR inhibitors. The aim of this study was to investigate the effects of combining the mTOR inhibitor temsirolimus (Tem) with the anti-EGFR agent cetuximab (Cet) and conventional chemotherapeutic drugs (cisplatin and fluorouracil (C/F)) on an orthotopic model of HNSCC.

STUDY DESIGN

Preclinical in vivo study.

METHODS

We evaluated the anti-tumor efficacy (measured tumor volume) of Tem, Cet, and C/F, administered alone or in combination. Investigations were performed using a human HNSCC cell line, CAL33, injected into the mouth floor of nude mice.

RESULTS

As compared with the control, the combination of Tem and Cet led to the highest tumor inhibition and induced almost complete tumor growth arrest (P = 0.001). Tem significantly enhanced the impact of the Cet-C/F combination on tumor growth (P < 0.001). The highest inhibitory effects of treatments on cell proliferation (Ki67 labeling), MAPK (pP42/44 labeling), and PI3K/AKT/mTOR (pS6R labeling) signaling pathways were found with the Tem-Cet association.

CONCLUSION

In this orthotopic HNSCC model, the combination of Tem with Cet produced synergistic effects on tumor growth. These results were corroborated by a strong inhibition of both MAPK and PI3K-mTOR signaling pathways.

LEVEL OF EVIDENCE

N/A.

DNA repair genes implicated in triple negative familial non-BRCA1/2 breast cancer predisposition

Among breast cancers, 10 to 15% of cases would be due to hereditary risk. In these familial cases, mutations in BRCA1 and BRCA2 are found in only 15% to 20%, meaning that new susceptibility genes remain to be found. Triple-negative breast cancers represent 15% of all breast cancers, and are generally aggressive tumours without targeted therapies available. Our hypothesis is that some patients with triple negative breast cancer could share a genetic susceptibility different from other types of breast cancers. We screened 36 candidate genes, using pyrosequencing, in all the 50 triple negative breast cancer patients with familial history of cancer but no BRCA1 or BRCA2 mutation of a population of 3000 families who had consulted for a familial breast cancer between 2005 and 2013. Any mutations were also sequenced in available relatives of cases. Protein expression and loss of heterozygosity were explored in tumours. Seven deleterious mutations in 6 different genes (RAD51D, MRE11A, CHEK2, MLH1, MSH6, PALB2) were observed in one patient each, except the RAD51D mutation found in two cases. Loss of heterozygosity in the tumour was found for 2 of the 7 mutations. Protein expression was absent in tumour tissue for 5 mutations. Taking into consideration a specific subtype of tumour has revealed susceptibility genes, most of them in the homologous recombination DNA repair pathway. This may provide new possibilities for targeted therapies, along with better screening and care of patients.

Quantification of HER family receptors in breast cancer

The clinical success of trastuzumab in breast cancer taught us that appropriate tumor evaluation is mandatory for the correct identification of patients eligible for targeted therapies. Although HER2 protein expression by immunohistochemistry (IHC) and gene amplification by fluorescence in situ hybridization (FISH) assays are routinely used to select patients to receive trastuzumab, both assays only partially predict response to the drug. In the case of epidermal growth factor receptor (EGFR), the link between the presence of the receptor or its amplification and response to anti-EGFR therapies could not be demonstrated. Even less is known for HER3 and HER4, mainly due to lack of robust and validated assays detecting these proteins. It is becoming evident that, besides FISH and IHC, we need better assays to quantify HER receptors and categorize the patients for individualized treatments. Here, we present the current available methodologies to measure HER family receptors and discuss the clinical implications of target quantification.

Can pathologic complete response (pCR) be used as a surrogate marker of survival after neoadjuvant therapy for breast cancer?

Breast cancer is heterogeneous in clinical, morphological, immunohistochemical and biological features, as reflected by several different prognostic subgroups. Neoadjuvant approaches are currently used for the "in vivo" efficacy assessment of treatments. Pathological complete response (pCR) has been reported as a reliable predictive factor of survival in that setting. However, pCR remains a subject of controversy in terms of definition and its evaluation methods. In addition, its predictive value for patient outcome in various breast cancer biological subtypes has been under debate. In this review, we will present the existing definitions of pCR, the impact of its evaluation methods on its rate and the assessment of its predictive value for patient outcome in the molecular subtypes of breast cancer (luminal A and B, Triple Negative and HER2-positive).

Abstract 550: Genomic instability and telomere characteristics as predictive biomarkers of therapeutic response in triple-negative breast cancer

Background. Triple negative breast cancers (TNBC) represent about 15 % of invasive breast carcinomas. These tumors are identified in clinical practice according to their “triple negative” immunophenotype (estrogen receptor, progesterone receptor and HER2 negative). TNBC show aggressive behavior and an unusual sarcoma-like pattern of metastasis. Identification of predictive biomarkers is critical to optimal therapeutic management of these tumors. TNBC are characterized by increased genomic instability. These tumors present complex pattern of numerous low-amplitude genomic gains and losses as well as shorter telomeres.

Aim. Identification of predictive biomarkers of response to neoadjuvant chemotherapy in TNBC by evaluating telomeric parameters and genomic instability.

Methods. We studied 38 TNBC patients treated with neoadjuvant chemotherapy according to the TVA protocol (FEC 100, docetaxel, panitumumab). DNA and RNA were extracted from snap-frozen tumor samples obtained before neoadjuvant therapy. The pathological response to treatment was evaluated according to Chevallier's and Sataloff's classifications and correlated with aCGH profiles (8x60K, Agilent) and telomere characteristics, including telomere length (qPCR) and expression (qRT-PCR) of telomerase (hTERT) and shelterin complex genes (TRF1, TRF2, POT1, TPP1, RAP1 and TIN2).

Results. Telomere shortening and high hTERT expression were found in more aggressive tumors according to TNM classification (P&lt; 0.04), and hTERT expression was also highly correlated with an increased tumor size (P= 0.0058). Short telomeres were strongly associated with incomplete histological response to neoadjuvant therapy according to Chevallier's (P= 0.0004) and Sataloff's classifications, (P= 0.0007). hTERT expression was significantly increased in cases with incomplete response (P&lt; 0.04). Among shelterin complex genes, TRF2 and TPP1 overexpression was found in more aggressive TNBC (according to TNM classification and SBR grading, P&lt; 0.05), but there was no correlation with pathological response. aCGH data indicated that genomic instability in non-responders was mainly represented by genomic gains. In particular, cases with incomplete therapeutic responses showed significantly larger size of gains than cases with complete responses. (P= 0.0089). Short telomeres were also associated with larger gains of genomic material (P= 0.0067). Of note, telomere shortening has been previously described as one of the mechanisms of genomic gains and amplifications.

Conclusions. Telomere shortening and hTERT overexpression were observed in resistant TNBC. Genomic profile of non-responding tumors was characterized by larger genomic gains. Telomere length, hTERT expression and genomic instability profiles may represent predictive biomarkers of response to neoadjuvant chemotherapy in TNBC.

Citation Format: Mathilde Gay-bellile, Nina Radosevic-Robin, Eleonore Eymard-Pierre, Fabrice Kwiatkowski, Marie-Mélanie Dauplat, Maud Privat, Catherine Abrial, Patricia Combes, Gwendoline Soler, Yves-Jean Bignon, Jean-Marc Nabholtz, Philippe Vago, Frédérique Penault-Llorca, Andreï Tchirkov. Genomic instability and telomere characteristics as predictive biomarkers of therapeutic response in triple-negative breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 550. doi:10.1158/1538-7445.AM2014-550