Physical characterization of3He ion beams for radiotherapy and comparison with4He

There is increasing interest in using helium ions for radiotherapy, complementary to protons and carbon ions. A large number of patients were treated with⁴He ions in the US heavy ion therapy project and novel⁴He ion treatment programs are under preparation, for instance in Germany and Japan.³He ions have been proposed as an alternative to⁴He ions because the acceleration of³He is technically less difficult than⁴He. In particular, beam contaminations have been pointed out as a potential safety issue for⁴He ion beams. This motivated a series of experiments with³He ion beams at Gesellschaft für Schwerionenforschung (GSI), Darmstadt. Measured³He Bragg curves and fragmentation data in water are presented in this work. Those experimental data are compared with FLUKA Monte Carlo simulations. The physical characteristics of³He ion beams are compared to those of⁴He, for which a large set of data became available in recent years from the preparation work at the Heidelberger Ionenstrahl-Therapiezentrum (HIT). The dose distributions (spread out Bragg peaks, lateral profiles) that can be achieved with³He ions are found to be competitive to⁴He dose distributions. The effect of beam contaminations on⁴He depth dose distribution is also addressed. It is concluded that³He ions can be a viable alternative to⁴He, especially for future compact therapy accelerator designs and upgrades of existing ion therapy facilities.

Evaluation of an amplicon-based custom gene panel for the diagnosis of hereditary tumors

Genetic testing based on next-generation sequencing (NGS) analysis has recently been used to diagnose hereditary diseases. In this study, we explored the usefulness of our custom amplicon panel that targeted 23 genes related to hereditary tumors given in the American College of Medical Genetics and Genomics recommendations. We applied our custom NGS panel to samples from 12 patients previously diagnosed by Sanger sequencing as having the diseases or diagnosed clinically by meeting the diagnostic criteria in this study. Our gene panel not only successfully identified all variants detected by Sanger sequencing but also identified previously unrecognized variants that resulted in confirmation of the disease, or even in the revision of the diagnosis. For instance, a patient identified with an SDHD gene mutation actually had von Hippel-Lindau (VHL) syndrome, as determined by the presence of a pathogenic VHL gene variant. We also identified false-positive results that were generated by amplification of genome regions that are not intended to be investigated. In conclusion, NGS-based amplicon sequencing is a highly effective method to detect germline variants, as long as they are also carefully reviewed by manual inspection.

Xenotransplantation-the current status and prospects

Introduction

There is a continuing worldwide shortage of organs from deceased human donors for transplantation into patients with end-stage organ failure. Genetically engineered pigs could resolve this problem, and could also provide tissues and cells for the treatment of conditions such as diabetes, Parkinson's disease and corneal blindness.

Sources of data

The current literature has been reviewed.

Areas of agreement

The pathobiologic barriers are now largely defined. Research progress has advanced through the increasing availability of genetically engineered pigs and novel immunosuppressive agents. Life-supporting pig kidneys and islets have functioned for months or years in nonhuman primates.

Areas of controversy

The potential risk of transfer of a pig infectious microorganism to the recipient continues to be debated.

Growing points

Increased attention is being paid to selection of patients for initial clinical trials.

Areas timely for developing research

Most of the advances required to justify a clinical trial have now been met.

Abstract P3-11-02: A randomized phase II trial of toremifene (120 mg) versus fulvestrant (500 mg) after prior non-steroidal aromatase inhibitor in postmenopausal women with hormone receptor-positive metastatic breast cancer (Hi-FAIR fx study)

Background: After the failure of a non-steroidal aromatase inhibitor (nsAI) for postmenopausal patients with advanced/metastatic breast cancer (BC), it is unclear which of the various kinds of endocrine monotherapy is the most appropriate. In a previous report it was found that toremifene 120 mg (TOR 120), a selective estrogen receptor modulator (SREM), was superior to steroidal AI in terms of progression-free survival after ns-AI in the Hi-FAIR ex trial. A phase II randomized trial of TOR 120 versus fulvestrant 500 mg (FUL 500), a selective estrogen receptor down regulator (SERD), was also conducted to select the most promising endocrine monotherapy after ns-AI in advanced/metastatic BC(Study registry number: UMIN000010087).

Patients and Methods: Postmenopausal women (n=106) with advanced/metastatic hormone-receptor positive BC from October 2011 to September 2014 were enrolled in this study. Fifty-three of the patients were randomly assigned to the TOR 120 (120 mg daily p.) group and 53 of the patients were randomly assigned to the FUL 500 group. In the FUL 500 group they were administered 500 mg of fulvestrant intramuscularly (im) on day 0, then 500 mg im on days 14 and 28 and every 28 days thereafter). If treatment failure occurred in either of the randomly assigned groups the patients were then removed and treated accordingly. A full analysis set was targeted for all cases that received the protocol treatment even once (TOR 120 (n=53) and FUL 500 (n=52)). The primary end point was the clinical benefit rate (CBR). The secondary end points were the objective response rate (ORR), progression-free survival (PFS), time to chemotherapy (TTCT), overall survival (OS), toxicity, and CBR, ORR and PFS after crossover of non-assigned treatment.

Results: A median follow up period of 30 months revealed that the CBR of FUL 500 (57.7%) tended to be superior to the CBR of TOR 120 (45.3%), the odds ratio (OR) was 1.70 (95% CI 0.74–3.62), and the median PFS was 7.8 months in the FUL 500 group and 5.8 months in the TOR 120 group. Moreover the hazard ratio (HR) was 0.79 (95% CI 0.52–1.21). However, there was no difference between the two groups in terms of ORR (17.7% and 15.1%, respectively), TTCT (13.3 months vs. 17.7 months, HR = 0.94 (95%CI 0.57 – 1.53)), and OS (33.4 months vs. not reached HR 1.29; 95% CI 0.80–2.09). At the cross-over phase, 33 and 24 patients after failure of assigned treatment were treated with FUL 500 and TOR 120, respectively. The CBR and PFS of FUL 500 after TOR 120 was better than that of TOR 120 after FUL 500 (CBR; 42.4% vs. 20.8%, OR = 0.33, 95%CI 0.09 – 1.11, median PFS; 6.2 months vs. 3.4 months; HR = 1.95, 95%CI 1.08–3.51). No difference between the two groups was observed in PFS from randomization to the end of the crossover phase. Moreover, there were few severe adverse events in either of the two groups.

Conclusions: FUL 500 used as a subsequent endocrine therapy for advanced/metastatic BC patients who failed ns-AI could potentially be more effective than TOR 120. However, the efficacy of SERM after failure of FUL 500 may be limited.

Citation Format: Nishimura R, Yamamoto Y, Narui K, Kijima Y, Hozumi Y, Ikeda M, Takao S, Ohtani S, Iwase H. A randomized phase II trial of toremifene (120 mg) versus fulvestrant (500 mg) after prior non-steroidal aromatase inhibitor in postmenopausal women with hormone receptor-positive metastatic breast cancer (Hi-FAIR fx study) [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 P3-11-02.

Bringing Home The Bacon: Update on The State of Kidney Xenotransplantation

BACKGROUND

There is a continuing critical shortage of organs from deceased human donors for transplantation, particularly for patients awaiting kidney transplantation. Efforts are being made to resolve the donor kidney shortage by the transplantation of kidneys from genetically-engineered pigs.

SUMMARY

This review outlines the pathobiological barriers to pig organ xenotransplantation in primates, which include (i) antibody-dependent complement-mediated rejection, (ii) a T cell-mediated elicited antibody and cellular response, (iii) coagulation dysregulation between pigs and primates, and (iv) a persistent inflammatory response. As a result of increasing genetic manipulation of the pig and the introduction of novel immunosuppressive agents, pig kidney graft survival has increased from minutes to months, and even to >1 year in some cases. Aspects of the selection of the patients for a first clinical trial are discussed. Although there would appear to be some cross-reactivity between anti-human leukocyte antigen (HLA) antibodies and swine leukocyte antigens expressed in pigs, some HLA-sensitized patients will be at no disadvantage if they receive a pig kidney. Furthermore, the current limited evidence is that, even if the patient becomes sensitized to pig antigens (after a pig organ transplant), this would not be detrimental to a subsequent allotransplant. The potential risk of infection with a pig microorganism, and the function of a pig kidney in a primate are also discussed. Key Message: The recent encouraging results of pig kidney transplantation in nonhuman primates suggest the likelihood of a successful (and safe) initial clinical trial, with graft survival for months or possibly years.

Abstract P6-09-46: A comprehensive analysis of GNAS DNA copy number, levels of mRNA and protein expression in primary breast cancer

Background: Result of recent advances in genetics, guanine nucleotide binding protein, alpha stimulating (GNAS), transducer of signals from G-protein coupled receptors, has been noted that this factor is related with the onset and progression of tumor in various cancers. We aimed to analyze gene amplification, mRNA and protein expression of GNAS and their potential association with clinicopathological factors and prognosis in primary breast cancer.

Methods: The cohort of this study included 432 primary invasive breast cancer patients treated with standard care at Kumamoto University Hospital between June 2000 and January 2011. We performed a comprehensive analysis of GNAS at the levels of gene copy number, mRNA and GNAS protein expression analyzed by qPCR, qRT-PCR and immunohistochemistry (IHC), respectively. In the IHC assessment of GNAS protein expression, an H-score<150 was observed in 191 patients (44.2%), who were defined as having a low protein expression level, and an H-score≥150 was observed in 241 patients (55.8%) who were defined as having a high protein expression level.

Results: The median age at diagnosis was 60 (range 27-93). Three hundred fifteen (72.9%) of these were postmenopausal women. One hundred forty two patients (32.9%) had axillary lymph node metastasis. The median Ki67 labeling index was 23.6 (range 0.5-97.0). The subtypes were 321 ER+/HER2-, 24 ER+/HER2+, 34 ER-/HER2+ and 53 ER-/HER2-. Three hundred twenty one patients (75.9%) were treated with endocrine therapy and 146 patients (34.6%) chemotherapy. Most notably, a low levels of GNAS protein expression was observed in 191(44.2%) patients, and was positivity associated with Ki67 (P=0.028). Furthermore, univariate and multivariate analysis revealed that low GNAS protein expression was significantly related with poor relapse-free survival rate (Log-rank test; P=0.0013, OR:0.40, 05%CI:0.22-0.70) and breast cancer specific survival rate (Log-rank-test; P=0.041, OR:0.43, 95%CI:0.19-0.97). GNAS amplification and mRNA expression were not correlated with prognoses.

Conclusion: Contrary to expectations, GNAS expression was positively related with favorable tumor characteristics. Expression levels of GNAS protein may be an independent prognostic factor for primary breast cancer.

Citation Format: Tomiguchi M, Yamamoto Y, Yamamoto-Ibusuki M, Goto-Yamaguchi L, Fujiki Y, Sueta A, Takeshita T, Iwase H. A comprehensive analysis of GNAS DNA copy number, levels of mRNA and protein expression in primary breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-46.

Abstract P1-02-09: Clinical significance of sequential measurements of ESR1 mutations in plasma cell-free DNA in estrogen receptor positive recurrent metastatic breast cancer patients

Background: The measurement of ESR1 mutations in plasma cell-free DNA (cfDNA) may transform the management of recurrent metastatic breast cancer (MBC) patients.

We aimed to investigate the clinical significance of sequential measurements of ESR1 mutations in MBC patients.

Methods: A total of 59 patients (113 plasma samples) with breast carcinoma were enrolled in this study. Cases were selected if archival plasma samples were available from PBC before and after treatment and from MBC gathered more than twice at the time of progression. cfDNA was isolated from the 17 PBC patients (34 plasma samples) and from the 42 MBC patients (99 plasma samples). To investigate any changes in each cfDNA ESR1 mutation before and after treatment, we analyzed the difference with cfDNA ESR1 mutations ratio in the first blood sample using droplet digital polymerase chain reaction (ddPCR).

Results:

The median changes in cfDNA ESR1 mutations ratio in the PBC group tended to be lower than that in the MBC group. The maximum change of each ESR1 mutation ratio in the PBC groups was used as the minimum cutoff for determining increases in cfDNA ESR1 mutation ratio. An increase in cfDNA ESR1 mutations was found in 13 plasma from 12 (28.6%) out of 42 MBC patients. 83.3% (10/12) of MBC patients with increase cfDNA ESR1 mutations showed a poor response to treatment. Interestingly, 12 MBC patients with increase cfDNA ESR1 mutations showed various response to endocrine therapy.

Patient characteristics of 12 MBC cases with increasing cell-free DNA ESR1 mutationsCaseAge at 1st blood drawSite of tissue biopsyIncreasing cfDNA ESR1 mutation  After increasing cfDNA ESR1 mutation analysis    2nd blood draw3rd blood draw4th blood drawETBOR to ET1866LungY537SNo riseNo riseLETPD2731LNY537S--LHRHa+ANAPD4458BreastD538GNo rise-FulPD5340OvaryY537S--No-5860BoneNo riseY537SNo riseNo-6267LNY537S--FulPD7261SkinY537N--EE2PR7561SkinNo riseY537NY537NFul /EXE+EVEPD/SD7748BoneNo riseY537S/D538G-No-8958BreastNo riseY537N-FulPD10168LungY537N--hdTORSD10856LNY537NNo rise-EE2PRAbbreviations: ER, estrogen receptor; PgR, progesteron receptor; HER2, human epidermal growth factor receptor 2; PBC, primary breast cancer; MBC, metastatic breast cancer receptor; cfDNA, cell-free DNA; ET, endocrine therapy; BOR, best overall response; LET, letrozole; PD, progressive disease; LN, lymph node; LHRHa, luteinizing hormone releasing hormone agonist; ANA, anastrozole; Ful, fulvestrant; EE2, ethinylestradiol; PR, partial response; EXE+EVE; exemestane+everolimus; SD, stable disease; hdTOR, high dose toremifene..

In survival analysis, increase cfDNA ESR1 mutations may predict a shorter duration of post-endocrine-therapy effectiveness (P = 0.0033).

Conclusions: We show that sequential measurements of the recurrent ESR1 mutation in plasma cfDNA of MBC patients is a feasible and useful method of providing relevant predictive information.

Citation Format: Takeshita T, Yamamoto Y, Yamamoto-Ibusuki M, Sueta A, Tomiguchi M, Iwase H. Clinical significance of sequential measurements of ESR1 mutations in plasma cell-free DNA in estrogen receptor positive recurrent metastatic breast cancer patients [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-02-09.

Abstract P1-02-13: Differential expression of exosomal miRNAs between breast cancer patients with recurrence and no-recurrence

Background

In recent years, there has been a concerted effort to identify biomarkers derived from body fluid in various cancers. Exosomal microRNA (miRNA) has been used as one of useful diagnostic or prognostic biomarkers. We aimed to investigate the prognostic role of the exosomal miRNAs in serum samples derived from patients with primary breast cancer. Additionally, we evaluated whether the exosomal miRNA in serum reflect the origin of primary tumor by means of comparing their expression levels between in serum and tumors.

Patients and Methods

Exosomes in serum sample (500uL) were extracted using ExoQuick (System Biosciences) and miRNAs were isolated using SeraMirTM Exosome RNA Amplification Kit (SBI). We compared the miRNA profile derived from exosome between the patients with breast cancer with recurrence (n=16) and without recurrence (n=16) by miRNA PCR array. Further, we examined the expression of miRNA derived from tumor tissues in the patients with breast cancer recurrence (n=35) and without recurrence (n=39) by qRT-PCR. All samples were collected before treatment and surgery.

Results

Of the 384 miRNAs, 11 miRNAs were significantly expressed; three miRNAs (miR-338-3p, miR-340-5p, and miR-124-3p) were significantly up-regulated and eight (miR-29b-3p, miR-20b-5p, miR-17-5p, miR-130a-3p, miR-18a-5p, miR-195-5p, miR-486-5p, and miR-93a-5p) were significantly down-regulated in the patients with recurrence compared to those without recurrence. Next, we evaluated expression of the above miRNAs in tumor tissues. The patients with recurrence have higher levels of miR-340 at their primary site as well as in the serum. On the contrary, miR-195-5p, miR-17-5p, miR-93-5p, and miR-130a-3p derived from tumor tissues that were down-regulated in the patients with recurrence in serum, were highly expressed in the patients with recurrence than those with no-recurrence. In logistic regression analysis, tumor size, miR-340-5p, miR-17-5p, miR-130a-3p, and miR-93-5p were significantly associated with breast cancer recurrence (each P < 0.05).

Conclusions

Several exosomal miRNAs at diagnosis may be useful biomarker to predict the breast cancer recurrence. Moreover, we showed the different expression pattern of miRNAs between tumor tissues and serum. These findings may suggest selective mechanism of release of exosomal miRNA by cancer cells to regulate their progression. Further studies to confirm our results are needed.

Citation Format: Sueta A, Yamamoto Y, Tomiguchi M, Takeshita T, Ibusuki M, Iwase H. Differential expression of exosomal miRNAs between breast cancer patients with recurrence and no-recurrence [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-02-13.

Abstract P3-05-10: Non-coding RNAs derived from near the ESR1 gene acts as a transcriptional regulator during estrogen deprivation adaptation of ER positive breast cancer cells

Endocrine therapies that blocks estrogen production are effective for estrogen receptor (ER)-positive breast cancer. However, endocrine therapy treated patients eventually experience relapse after a long period of estrogen deprivation. The mechanism underlying acquisition of estrogen independent growth by ER positive breast cancer cells remains unclear.

To understand such molecular mechanism, we used a cell model LTED (long term estrogen deprivation) which MCF7 cells were cultured under estrogen deprivation for 4-10 months. In LTED cells, we found that ER encoded gene ESR1 was up-regulated and ER overproduction was essential for estrogen-independent cell growth. We also revealed that RNA transcriptions of the ESR1 and several neighbor genes were co-induced from both coding and non-coding regions in LTED cells, using RNA-sequence. These highly transcribed regions were corresponded to active histone modifications and transcription factor bindings according to publically available genome-wide analyses data. Fluorescence in situ hybridization (FISH) analyses indicated that RNA from the chromatin domain region nearby ESR1 were co-localized and made foci in nucleus.

We found non-coding regions that are particularly highly transcribed. FISH analyses indicated that RNAs from these regions might interact with the parental ESR1 gene locus. Recent studies have shown that non-coding RNAs are involved in transcriptional regulation and chromatin regulation. To understand the role of the non-coding RNA, we have generated MCF7 cells lines that lack the non-coding site, using CRISPR/CAS9 system. We found that mRNA transcription of multiple genes including ESR1 were impaired by the deletion. These findings suggested that these non-coding RNAs may be involved in chromatin regulation of the chromatin domain nearby ESR1.

In this study, we found non-coding RNAs that control transcription of chromatin domain genes in ER positive breast cancer cells. Such non-coding RNA mediated transcriptional regulation might be critical for endocrine therapy resistance adaptation.

Citation Format: Fujiwara S, Saitoh N, Tomita S, Abdalla MO, Iwase H, Nakao M. Non-coding RNAs derived from near the ESR1 gene acts as a transcriptional regulator during estrogen deprivation adaptation of ER positive breast cancer cells. [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 P3-05-10.

Abstract P6-07-07: Clinical significance of ESR1 mutations using droplet digital polymerase chain reaction assay in 325 breast cancer samples

Purpose: We aimed to develop a droplet digital Polymerase Chain Reaction (ddPCR)-based method for the sensitive detection of estrogen receptor (ER) α (ESR1) mutations in the primary and recurrent/metastatic tumor tissues of breast cancer.

Experimental Design: We studied a total of 325 tumor specimens (270 primary breast cancer specimens and 55 ER-positive recurrent/metastatic tumor specimens). Because the recurrent/metastatic tumor specimens had much inflammatory and stromal cells, we captured only tumor cells using laser microdissection. We investigated the quantification of rare ESR1 mutations, four representative types, Y537S, Y537N, Y537C, and D538G in extracted genomic DNA using ddPCR system that simultaneously performed thousands of PCRs on a nanoliter scale.

Results: In 270 primary breast cancer samples, we analyzed each ESR1 alteration percentage in each subtype. ESR1 Y537C tended to be higher in hormone receptor-positive (HR+)/ human epidermal growth factor receptor 2-negative (HER2-) group (P = 0.06) and higher percentage of ESR1 D538G was statistically significant in HR+/ HER2- group (P = 0.027), compared with HER2+ group. There was no statistically different in each ESR1 alteration percentage between HR+/ HER2- group and HR-/ HER2- group. Whether each ESR1 alteration was dichotomized as positive or not, we used the percentage which HER2+ group and HR-/ HER2- were not identified, as a cutoff point. ESR1 mutations occurred in 7 samples (2.5%) out of 270 primary samples, but ESR1 mutations occurred in 11 samples (20%) out of 55 metastatic/ recurrent breast cancer samples.

Table 1 Patients characteristics of 11 metastatic ER-positive breast cancer cases with ESR1 mutationsCaseAge (years)HER2 statusKi67 LIER HSPgR HSBiopsy siteMutation472-102051Lymph nodeY537C 1610 A>G only665-518218Lymph nodeY537S 1610 A>C Y537N 1609 T>A D538G 1613 A>G1555-201105SkinY537C 1610 A>G only1863-10162130Lymph nodeD538G 1613 A>G only3354-417015Lymph nodeY537S 1610 A>C Y537N 1609 T>A D538G 1613 A>G4268-516950SkinY537C 1610 A>G only4466-24270159Lymph nodeY537N 1609 T>A only4673-20224110Lymph nodeY537N 1609 T>A and D538G 1613 A>G4952-20275138SkinY537S 1610 A>C and Y537C 1610 A>G5040-101740Lymph nodeY537S 1610 A>C only5140-101895IBTRY537S 1610 A>C onlyAbbreviations: HER2, human epidermal growth factor receptor 2; LI, labeling index; ER, estrogen receptor; HS, histoscore; PgR, progesteron receptor; ET, endocrine therapy; IBTR, ipsilateral breast tumor recurrence; SD, stable disease; PD, progressive disease; MPA, medroxyprogesterone acetate

Two biopsies were performed in 8 women, in which four women had primary and recurrent/metastatic samples. Four out of these 8 women acquired ESR1 mutation, whereas no ESR1 mutation could be identified at first biopsy.

Conclusions: We demonstrated the sensitive detection and accurate quantification of low frequency ESR1 mutations in 270 primary breast cancer samples and 55 recurrent/metastatic samples using ddPCR assay. This technique could prove a useful method for the precise detection of ESR1 mutations in endocrine therapy resistant cases.

Citation Format: Takeshita T, Yamamoto Y, Yamamoto-Ibusuki M, Inao T, Sueta A, Fujiwara S, Iwase H. Clinical significance of ESR1 mutations using droplet digital polymerase chain reaction assay in 325 breast cancer samples. [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 P6-07-07.

Abstract P3-07-11: High activation of PI3K pathway defined by PIK3CA mutation, PTEN, and INPP4B expression are associated with trastuzumab efficacy in HER2-positive breast cancer

Background

Aberrations of phosphoinositide-3-kinase (PI3K) pathway are extensively found in many human cancers through several mechanisms, including mutation or amplification of PIK3CA and loss of phosphatase and tensin homolog (PTEN) and inositol polyphosphate 4-phosphatase-II(INPP4B). In breast cancer, a number of studies have suggested the putative mechanism of resistance to trastuzumab therapy in terms of PI3K pathway activation. We aimed to evaluate the predictive relevance of these biomarkers to trastuzumab efficacy in HER2-positive disease.

Patients and Methods

A total of 43 breast cancer patients with HER2-positive who received both neoadjuvant treatment and surgery at Kumamoto University Hospital between 2004 and 2012 were selected. The regimens of chemotherapy included anthracycline or taxane-containing drugs in combination with trastuzumab. Using pretreatment tumor tissues, PIK3CA mutations (E542K, E545K, and H1047R) were analyzed by direct dideoxynucleotide sequencing and digital PCR methods. Additionally, the expressions of PTEN, pAkt, and INPP4B were assessed by immunohistochemistry (IHC).

Results

The overall pathological complete response (pCR) rate was 60%. Direct sequencing detected PIK3CA mutations in 21% of all patients, whereas digital PCR detected them in 26 % when the cutoff point of the mutation was set at 1%. In some cases, it was difficult to differentiate mutant DNA from artifact by direct sequencing, but we could identify the mutation clearly using digital PCR. We found the correlation between the proportion of the PIK3CA mutation and the pCR rate; the pCR rates in the patients with PIK3CA mutations with cut-off of 1%, 10% and 20% were 55%, 29%, and 0%, respectively.

There were no significant correlations of clinicopathological features with PIK3CA mutations, copy number status, PTEN, and pAkt expression. Low INPP4B expression was associated with larger tumor size (P = 0.035), and higher nuclear grade (P = 0.031) compared to high expression.

We evaluated the contribution of biomarkers related to the PI3K pathway to the prediction of pCR by logistic regression models. In multivariate analysis, activation of the PI3K pathway due to either PIK3CA mutation or low PTEN expression were related to poorer response to trastuzumab (OR of predictive pCR was 0.11, P = 0.041). Similarly, high activation defined as PIK3CA mutation or low expression of PTEN or INPP4B tend to have lower pCR (OR was 0.14, P = 0.064).

Conclusions

1. Digital PCR has potential to complement the direct sequencing data, leading to more accurate measurement of the mutation frequency.

2. Our findings provide additional support for the recently published studies regarding activating mutation in PIK3CA in HER2-positive breast cancer, and further suggest that integrated biomarkers of PIK3CA mutation, PTEN, INPP4B are stronger predictors of trastuzumab response than either one alone.

Citation Format: Sueta A, Yamamoto Y, Takeshita T, Yamamoto-Ibusuki M, Iwase H. High activation of PI3K pathway defined by PIK3CA mutation, PTEN, and INPP4B expression are associated with trastuzumab efficacy in HER2-positive 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 P3-07-11.

Abstract P4-09-01: FGFR1 protein expression is associated with prognosis in primary breast cancer: A comprehensive analysis of gene copy number, mRNA and protein expression

Background: The Cancer Genome Atlas (TCGA) showed that copy number gain/amplification of FGFR1 was around 10% in primary breast cancer. FGFR1 gene amplification in breast cancer has been reported in some studies, more likely seen in ER-positive subtype. Several preclinical and clinical studies demonstrated that FGFR1 was one of novel targets of therapy for metastatic breast cancer. Previous studies suggested that aberrant FGFR1 expression was associated with poor prognosis, while there was no report that compared copy number aberration, mRNA and protein expression. The aim of this study is to analyze FGFR1 gene copy number, expression levels of FGFR1 mRNA and FGFR1 protein in ER-positive/HER2-negative primary breast cancer, and to examine the relationship between FGFR1 status and clinicopathological parameters including prognosis.

Methods: The cohort of this study included 307 ER-positive/HER2-negative primary invasive breast cancer patients treated with standard care at Kumamoto University Hospital between June 2000 and January 2011. We performed a comprehensive analysis of FGFR1 at the levels of gene copy number, mRNA and FGFR1 protein expression analyzed by qPCR, qRT-PCR and immunohistochemistry, respectively.

Results: FGFR1 gain/amplification was identified in 43 (14.0%) out of 307 patients. FGFR1 gain/amplification had significantly associated with higher nuclear grade (p=0.010). No correlations between FGFR1 mRNA expression levels and any clinicopathological factors were found. Expression levels of FGFR1 protein was positively associated with invasive tumor size (p=0.039). Modest positive correlations between these three (FGFR1 gene gain/amplification, expression levels of FGFR1 mRNA and FGFR1 protein) were found. The univariate analysis revealed that high FGFR1 protein expression was significantly related to poor prognosis (p=0.0019, HR: 2.63, 95%CI: 1.17-5.98) in terms of relapse-free survival (RFS) but not breast cancer-specific survival. The univariate analysis did not show that any factors except FGFR1 protein expression were significantly associated with RFS in this cohort.

Conclusion: Expression levels of FGFR1 protein may be an independent prognostic factor in terms of RFS for ER-positive/HER2-negative breast cancer patients receiving standard care.

Citation Format: Tomiguchi M, Yamamoto Y, Yamamoto-Ibusuki M, Yamaguchi R, Fujiki Y, Fujiwara S, Sueta A, Takeshita T, Inao T, Iwase H. FGFR1 protein expression is associated with prognosis in primary breast cancer: A comprehensive analysis of gene copy number, mRNA and protein expression. [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 P4-09-01.

Initial in vivo experience of pig artery patch transplantation in baboons using mutant MHC (CIITA-DN) pigs

BACKGROUND

In the pig-to-nonimmunosuppressed baboon artery patch model, a graft from an α1,3-galactosyltransferase gene-knockout pig transgenic for human CD46 (GTKO/CD46) induces a significant adaptive immune response (elicited anti-pig antibody response, increase in T cell proliferation on MLR, cellular infiltration of the graft), which is effectively prevented by anti-CD154mAb-based therapy.

METHODS

As anti-CD154mAb is currently not clinically applicable, we evaluated whether it could be replaced by CD28/B7 pathway blockade or by blockade of both pathways (using belatacept + anti-CD40mAb [2C10R4]). We further investigated whether a patch from a GTKO/CD46 pig with a mutant human MHC class II transactivator (CIITA-DN) gene would allow reduction in the immunosuppressive therapy administered.

RESULTS

When grafts from GTKO/CD46 pigs were transplanted with blockade of both pathways, a minimal or insignificant adaptive response was documented. When a GTKO/CD46/CIITA-DN graft was transplanted, but no immunosuppressive therapy was administered, a marked adaptive response was documented. In the presence of CD28/B7 pathway blockade (abatacept or belatacept), there was a weak adaptive response that was diminished when compared with that to a GTKO/CD46 graft. Blockade of both pathways prevented an adaptive response.

CONCLUSION

Although expression of the mutant MHC CIITA-DN gene was associated with a reduced adaptive immune response when immunosuppressive therapy was inadequate, when blockade of both the CD40/CD154 and CD28/B7 pathways was present, the response even to a GTKO/CD46 graft was suppressed. This was confirmed after GTKO/CD46 heart transplantation in baboons.

Evaluation of a personal identification method using the fusion function of CT images and dental radiographs

OBJECTIVES

We applied the fusion function of dental analysis software to examine whether the anatomical relationships of tooth roots when compared between reconstructed post-mortem CT (PMCT) and dental radiographs can aid dental identification.

METHODS

One PMCT image taken from a cadaver (43-year-old male; Cadaver 1) was compared with 64 digital dental radiographs of the left and right upper and lower molars from Cadaver 1 and 30 other cadavers. Five corresponding anatomical reference points were marked on each image. After adjusting the angle and magnification using the fusion function, the automatically calculated error in pixels was determined five times for each of four sites on the images.

RESULTS

Comparison of the PMCT image with the dental radiographs from the other cadavers revealed obvious discrepancies in the anatomical positioning of the teeth. When t-tests were applied to the data from any of the four sites, the error in pixels was found to be significantly smaller (p < 0.001) between Cadaver 1 and the other cadaver images. The average error in pixels between the PMCT and dental radiographs was smaller in the lower jaw than in the upper jaw.

CONCLUSIONS

This method uses corresponding reference points on two images to calculate the error between the regions that contain all points. This feature also makes it possible to compare images taken with different modalities. The demand for a dental identification method involving PMCT is likely to increase, and we expect that the accuracy of dental identification will improve by using radiological images.

Abstract P5-01-13: Poly(I:C), an innate adjuvant receptor ligand, can induce the antitumor effects on human breast cancer cells

[Background] Innate adjuvant receptors are expressed in immune cells and some types of cancers. If antitumor therapies targeting adjuvant receptors in cancer cells are established, it could be therapeutically useful because antitumor effects and activation of the immune system can be induced simultaneously.

[Objective]Poly(I:C) is one of innate adjuvant receptors ligands and triggers signaling through not only endosome Toll-like receptor (TLR) 3 but also cytoplasmic melanoma differentiation-associated gene (MDA) 5. In this study, we investigated antitumor effects of poly(I:C) on human breast cancer cell lines, and then elucidated the mechanisms.

[Methods] Three breast cancer cell lines (MCF-7, MDA-MB-231, and BT-549) were used in this study. Poly(I:C) was transfected into these cancer cells, and cell viability and apoptosis were evaluated by WST8 assay and flow cytometry, respectively. The expression of adjuvant receptors and cell cycle-related molecules were examined by immunobotting. Autophagy was evaluated by immunoblotting and confocal imaging. In vivo antitumor effect was determined using a xenograft mouse model.

[Results] All three cell lines were positive for both TLR3 and MDA5. Poly(I:C) transfection drastically reduced their cell viabilities in a partially MDA5-dependent manner. Poly(I:C)-transfected cancer cells showed caspase-dependent apoptosis and growth arrest as a result of suppression of c-Myc and cyclinD1. Interestingly, poly(I:C) transfection was accompanied by autophagy, which is known to work cytoprotectively under starvation and stress, and knockdown of beclin-1, an essential molecule for autophagy, by RNA interference promoted poly(I:C) transfection-induced apoptosis. In vivo poly(I:C) transfection exerted the antitumor effect on xenografted MDA-MB-231 in nude mice.

[Conclusions] These results suggest that the innate adjuvant receptors are promising targets in human breast cancer and that autophagy plays a protective role in this treatment modality.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-01-13.

Abstract P1-14-04: Subsequent endocrine therapy after becoming to resistance of ‘estrogen therapy’ is beneficial as a salvage treatment for the late stage metastatic breast cancer

BACKGROUND: Aromatase inhibitor (AI) is a most commonly used as the endocrine therapy in postmenopausal hormone-dependent breast cancer. Paradoxically, estrogen additive therapy, high-dose estrogen using ethinylestradiol, can be useful after long-term estrogen deprivation therapies with AI. Furthermore, there is a possibility of the beneficial effect of AI or fulvestrant as a subsequent endocrine therapy after EE2 failure.

METHODS: Ethinylestradiol (EE2; 3mg/day, TID) therapy was performed in 22 patients with metastatic breast cancer (median; 62 years-old, the mean observation time: 13.6 months.), who were heavily treated by sequential endocrine therapies (3rd or more line) including cytotoxic chemotherapies. We examined the efficacy of a subsequent endocrine therapy using aromatase inhibitor or fulvestrant after becoming resistance to the EE2 therapy in the patients who got the disease control by the prior EE2 therapy. The primary endpoint was clinical benefit rate (CBR) and the secondary endpoint was time to treatment failure (TTF). (Registration number; UMIN 000002831, additional analysis)

RESULTS: Median of TTF of EE2 treatment was 46 weeks (23-62+, 2 cases were ongoing). The response rate was 41% (9/22), the clinical benefit rate was 50% (11/22). The stable disease (&lt; 6 months) was 18% (4/22) and another 3 cases were judged as progressive disease. Four cases withdrew due to nausea, fatigue and muscle-skeletal pain. In 13 cases progressed after disease control (SD or more) of EE2, a subsequent endocrine therapy, fulvestrant for 6 cases and AI for 7 cases, was performed. Fulvestrant group showed 50% (3 in 6) of CBR and 15 weeks (5-55+) of TTF, and AI-treated group showed 43% (3 in 7) of CBR and 19 weeks (5-33+) of TTF. Two in three cases, who became resistance to anti-estrogen treatment, got long SD by further EE2 re-therapy.

DISCUSSION: EE2 therapy could be beneficial for heavily treated metastatic breast cancer. Some cases showed clinical benefits of a subsequent therapy by AI or fulvestrant after becoming to EE2 failure. Taken together, sequential use of estrogen and anti-estrogen therapy (vice versa) could be one of the options as a salvage endocrine therapy for the end stage breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-14-04.