Blocking soluble TNFα sensitizes HER2-positive breast cancer to trastuzumab through MUC4 downregulation and subverts immunosuppression

BACKGROUND

The success of HER2-positive (HER2+) breast cancer treatment with trastuzumab, an antibody that targets HER2, relies on immune response. We demonstrated that TNFα induces mucin 4 (MUC4) expression, which shields the trastuzumab epitope on the HER2 molecule decreasing its therapeutic effect. Here, we used mouse models and samples from HER2+ breast cancer patients to unravel MUC4 participation in hindering trastuzumab effect by fostering immune evasion.

METHODS

We used a dominant negative TNFα inhibitor (DN) selective for soluble TNFα (sTNFα) together with trastuzumab. Preclinical experiments were performed using two models of conditionally MUC4-silenced tumors to characterize the immune cell infiltration. A cohort of 91 patients treated with trastuzumab was used to correlate tumor MUC4 with tumor-infiltrating lymphocytes.

RESULTS

In mice bearing de novo trastuzumab-resistant HER2+ breast tumors, neutralizing sTNFα with DN induced MUC4 downregulation. Using the conditionally MUC4-silenced tumor models, the antitumor effect of trastuzumab was reinstated and the addition of TNFα-blocking agents did not further decrease tumor burden. DN administration with trastuzumab modifies the immunosuppressive tumor milieu through M1-like phenotype macrophage polarization and NK cells degranulation. Depletion experiments revealed a cross-talk between macrophages and NK cells necessary for trastuzumab antitumor effect. In addition, tumor cells treated with DN are more susceptible to trastuzumab-dependent cellular phagocytosis. Finally, MUC4 expression in HER2+ breast cancer is associated with immune desert tumors.

CONCLUSIONS

These findings provide rationale to pursue sTNFα blockade combined with trastuzumab or trastuzumab drug conjugates for MUC4+ and HER2+ breast cancer patients to overcome trastuzumab resistance.

Abstract P5-13-32: Mucin 4 expression in high risk breast cancer: Predicting and overcoming resistance to immunotherapy

Background HER2-positive (+) and triple negative breast cancer (TNBC) have the worst survival among BC. BC patients are treated with chemotherapy (CT) and/or radiotherapy (RT), and HER2+ BC patients also receive targeted therapies, such as trastuzumab (Tz). The abundance of tumor infiltrating lymphocytes (TILs), in both HER2+ and TNBC, has a major good prognostic value. Thus, indicating that immunological evasion mechanisms are present in the tumor microenvironment (TME) hampering the efficacy of the treatments. We previously showed that soluble tumor necrosis factor α (sTNF) induces upregulation of mucin 4 (MUC4), which shields Tz epitope on HER2 impairing Tz binding and its effects. In preclinical models of de no5vo Tz-resistant tumors, administration of the sTNF blocking agent INB03 (DN) together with Tz inhibited tumor growth. We proved that MUC4 expression is an independent predictor of poor DFS in patients treated with adjuvant Tz. Our goal is to study whether MUC4 plays a role in tumor immune evasion in HER2+ and TNBC. Methods Untreated primary BC samples were assessed for TILs density (H&E) and MUC4 expression by immunohistochemistry. Tumors with TILs ≥30% and >50%, for TNBC and HER2+ BC respectively, and MUC4 scores 2 and 3 (0-3) were deemed positive. A cohort of 56 TNBC and 90 HER2+BC, stage I-III were retrospectively retrieved from Hospital Fernández and Instituto Henry Moore from 2013-2017, and clinicopathological and treatment characteristics were obtained from electronic records. TNBC were treated with adjuvant (41) or neoadjuvant CT +/- RT (15). HER2+BC patients received adjuvant Tz + CT. The association between MUC4 and OS was assessed by Kaplan Meier and log rank test and between MUC4 and TILs using Chi2. JIMT-1 HER2+ BC, de novo resistant tumors to Tz, containing a doxycycline (Dox)-inducible shRNA MUC4 plasmid (JIMT-1shMUC4) growing in nude mice were treated with IgG, Tz, DN or Tz + DN. Tumor growth was measured and macrophages and NK cells were determined in the TME by flow cytometry. Anti-asialo GM1 and clodronate-encapsulated liposomes were used to deplete NK cells and macrophages, respectively. Results We found an inverse relationship between TILs and MUC4 expression in HER2+ and TNBC (P=0.02 and P= 5 x10-5, respectively). Patients with MUC4+ TNBC have a shorter OS (P=0.03) and MUC4 was an independent predictor of OS [P=0.01; HR 4.9 (95%CI 1.4-17.0)]. To study MUC4 involvement in macrophage and NK cells recruitment in a Tz resistant model, nude mice bearing JIMT-1-shMUC4 tumors were treated or not with Dox to abolish MUC4 expression. Both groups received IgG, Tz, DN or DN + Tz. In control groups (without Dox), only Tz + DN administration was able to inhibit tumor growth (75% inhibition, P<0.0001 vs. IgG), in line with our previous results, and DN treatment reduced MUC4 expression. Knockdown of MUC4 expression by Dox, showed that Tz alone was effective in inhibiting JIMT-shMUC4 tumor growth at similar levels than Tz + DN group. Tumor growth inhibition was accompanied by an increase in NK cells activation and degranulation, and a rise in M1/M2 macrophage ratio. Depletion of macrophages or NK cells totally blunted antitumor effect of Tz + DN in control tumors. In MUC4-silenced tumors only macrophage depletion was able to abolish Tz antitumor effect. Conclusion Our results suggest that i) MUC4 expression is associated with immunologically “cold” HER2+ and TNBC, inducing an immunosuppressive TME that reflects in poor DFS/OS, and it confers resistance to Tz in HER2+ BC; ii) elimination of MUC4 expression reverses resistance to Tz; iii) tumor infiltrating macrophages are critical to the anti-tumor response in HER2+ BC. Patients with MUC4+ HER2+ or MUC4+ TNBC should benefit from sTNF blockade treatment leading to MUC4 downregulation and higher TILs, which would result in a better response to Tz and probably to immune checkpoint inhibitors.

Citation Format: Roxana Schillaci, Sofia Bruni, Florencia Mauro, María F Mercogliano, Agustina Roldan-Deamicis, Cecilia J Proietti, Rosalía Cordo-Russo, Gloria Inurrigarro, Agustina Dupont, Carla Adami, Daniel Lopez Della Vecchia, Sabrina Barchuck, Silvina Figurelli, Ernesto Gil Deza, Sandra Ares, Felipe G Gercovich, Patricia V Elizalde. Mucin 4 expression in high risk breast cancer: Predicting and overcoming resistance to immunotherapy [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-13-32.

The tale of TILs in breast cancer: A report from The International Immuno-Oncology Biomarker Working Group

The advent of immune-checkpoint inhibitors (ICI) in modern oncology has significantly improved survival in several cancer settings. A subgroup of women with breast cancer (BC) has immunogenic infiltration of lymphocytes with expression of programmed death-ligand 1 (PD-L1). These patients may potentially benefit from ICI targeting the programmed death 1 (PD-1)/PD-L1 signaling axis. The use of tumor-infiltrating lymphocytes (TILs) as predictive and prognostic biomarkers has been under intense examination. Emerging data suggest that TILs are associated with response to both cytotoxic treatments and immunotherapy, particularly for patients with triple-negative BC. In this review from The International Immuno-Oncology Biomarker Working Group, we discuss (a) the biological understanding of TILs, (b) their analytical and clinical validity and efforts toward the clinical utility in BC, and (c) the current status of PD-L1 and TIL testing across different continents, including experiences from low-to-middle-income countries, incorporating also the view of a patient advocate. This information will help set the stage for future approaches to optimize the understanding and clinical utilization of TIL analysis in patients with BC.

Abstract P6-20-14: Neutralizing soluble tumor necrosis factor alpha overcomes trastuzumab-resistant breast cancer immune evasion by downregulating mucin 4, improving NK cell function and decreasing myeloid-derived suppressor cells in tumor microenvironment

Background: Novel strategies aimed to overcome trastuzumab (Tz) resistance of HER2+ breast cancer (BC) are needed. Recently, we demonstrated a novel immune evasion strategy used by BC where tumor necrosis factor alpha (TNF) induces upregulation of the transmembrane glycoprotein mucin 4 (MUC4) via NF-kB activation to impair Tz binding that prevents antibody mediated killing of BC cells. Etanercept, a non-selective inhibitor of soluble and transmembrane TNF (sTNF, tmTNF), downregulated MUC4 expression and sensitized de novo Tz-resistant BC xenografts to Tz. Moreover, we showed that MUC4 expression is an independent predictor of poor disease-free survival in patients treated with Tz in the adjuvant setting (Clin Cancer Res 2017, 23:636). Etanercept is immunosuppressive due to off-target effects on tmTNF while selective inhibition of sTNF improves the immune response to the tumor (Cancer Immunol Res 2016, 4:441). Because of the immunosuppressive properties of etanercept, we wanted study if the dominant negative-TNF protein XPro1595 (DN-TNF; also known as INB03) that neutralizes sTNF without affecting tmTNF is able to downregulate MUC4 to inhibit Tz-resistant tumor growth and improve innate antitumor immune response.

Methods: To assess the effect of DN-TNF on Tz-resistant HER2+ tumor growth, JIMT-1 cells were s.c. injected in nude mice. When tumors were established, animals were treated with IgG, DN-TNF, Tz or DN-TNF+Tz, i.p. twice a week for one month. Innate immune response was determined by flow cytometry analysis of NK cells activation and degranulation and myeloid-derived suppressor cells (MDSC) subtypes in tumor microenvironment (TME) and in spleen. Tz-dependent NK cells degranulation was assessed in splenocytes using HER2+, Tz-sensitive cell line BT-474 as the target. MUC4 and phospho NF-kB expression was determined by Western blot.

Results: Treatment with Tz or DN-TNF had no impact on JIMT-1 tumor growth. However, co-treatment with DN-TNF and Tz resulted in significantly less growth. At day 21st, tumor volume was 75mm3 in DN-TNF+Tz vs 300mm3 control groups. DN-TNF+Tz treatment showed a decrease in myeloid cell infiltration and MDSC phenotype was enriched in the granulocytic-MDSC vs monocytic-MDSC suggesting a less immunosuppressive TME. DN-TNF+Tz administration significantly increased activation and degranulation of tumor infiltrating NK cells. In addition, spleen NK cells from these animals exhibited enhanced Tz-dependent degranulation vs control groups. MUC4 expression was downregulated in tumors treated with DN-TNF and NF-kB phosphorylation was inhibited (all comparisons p<0.05).

Conclusion: These results suggest that targeting sTNF together with Tz treatment improves antitumor immune response reducing tumor burden. Activated NK cells can more effectively attack the tumor due to a less suppressive TME and decreased MUC4 expression enhancing Tz binding in Tz-resistant HER2+ BC. Patients with increased levels of TNF expressing MUC4 in their tumors could be eligible for a combined therapy with DN-TNF and Tz to overcome/avoid resistance to therapy. These results can be translated quickly into the clinic.

Citation Format: Schillaci R, Bruni S, De Martino M, Mercogliano MF, Inurrigarro G, Frahm I, Proietti CJ, Elizalde PV. Neutralizing soluble tumor necrosis factor alpha overcomes trastuzumab-resistant breast cancer immune evasion by downregulating mucin 4, improving NK cell function and decreasing myeloid-derived suppressor cells in tumor microenvironment [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 P6-20-14.

Invasive micropapillary carcinoma of the breast overexpresses MUC4 and is associated with poor outcome to adjuvant trastuzumab in HER2-positive breast cancer

Background

Invasive micropapillary carcinoma of the breast (IMPC) is a histological tumor variant that occurs with low frequency characterized by an inside-out formation of tumor clusters with a pseudopapillary arrangement. IMPC is an aggressive tumor with poor clinical outcome. In addition, this histological subtype usually expresses human epidermal growth factor receptor 2 (HER2) which also correlates with a more aggressive tumor. In this work we studied the clinical significance of IMPC in HER2-positive breast cancer patients treated with adjuvant trastuzumab. We also analyzed mucin 4 (MUC4) expression as a novel biomarker to identify IMPC.

Methods

We retrospectively studied 86 HER2-positive breast cancer patients treated with trastuzumab and chemotherapy in the adjuvant setting. We explored the association of the IMPC component with clinicopathological parameters at diagnosis and its prognostic value. We compared MUC4 expression in IMPC with respect to other histological breast cancer subtypes by immunohistochemistry.

Results

IMPC, either as a pure entity or associated with invasive ductal carcinoma (IDC), was present in 18.6% of HER2-positive cases. It was positively correlated with estrogen receptor expression and tumor size and inversely correlated with patient’s age. Disease-free survival was significantly lower in patients with IMPC (hazard ratio = 2.6; 95%, confidence interval 1.1–6.1, P = 0.0340). MUC4, a glycoprotein associated with metastasis, was strongly expressed in all IMPC cases tested. IMPC appeared as the histological breast cancer subtype with the highest MUC4 expression compared to IDC, lobular and mucinous carcinoma.

Conclusion

In HER2-positive breast cancer, the presence of IMPC should be carefully examined. As it is often not informed, because it is relatively difficult to identify or altogether overlooked, we propose MUC4 expression as a useful biomarker to highlight IMPC presence. Patients with MUC4-positive tumors with IMPC component should be more frequently monitored and/or receive additional therapies.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3897-x) contains supplementary material, which is available to authorized users.

TNFα-Induced Mucin 4 Expression Elicits Trastuzumab Resistance in HER2-Positive Breast Cancer

PURPOSE

Although trastuzumab administration improved the outcome of HER2-positive breast cancer patients, resistance events hamper its clinical benefits. We demonstrated that TNFα stimulation in vitro induces trastuzumab resistance in HER2-positive breast cancer cell lines. Here, we explored the mechanism of TNFα-induced trastuzumab resistance and the therapeutic strategies to overcome it.

EXPERIMENTAL DESIGN

Trastuzumab-sensitive breast cancer cells, genetically engineered to stably overexpress TNFα, and de novo trastuzumab-resistant tumors, were used to evaluate trastuzumab response and TNFα-blocking antibodies effectiveness respectively. Immunohistochemistry and antibody-dependent cell cytotoxicity (ADCC), together with siRNA strategy, were used to explore TNFα influence on the expression and function of its downstream target, mucin 4 (MUC4). The clinical relevance of MUC4 expression was studied in a cohort of 78 HER2-positive breast cancer patients treated with adjuvant trastuzumab.

RESULTS

TNFα overexpression turned trastuzumab-sensitive cells and tumors into resistant ones. Histopathologic findings revealed mucin foci in TNFα-producing tumors. TNFα induced upregulation of MUC4 that reduced trastuzumab binding to its epitope and impaired ADCC. Silencing MUC4 enhanced trastuzumab binding, increased ADCC, and overcame trastuzumab and trastuzumab-emtansine antiproliferative effects in TNFα-overexpressing cells. Accordingly, administration of TNFα-blocking antibodies downregulated MUC4 and sensitized de novo trastuzumab-resistant breast cancer cells and tumors to trastuzumab. In HER2-positive breast cancer samples, MUC4 expression was found to be an independent predictor of poor disease-free survival (P = 0.008).

CONCLUSIONS

We identified TNFα-induced MUC4 expression as a novel trastuzumab resistance mechanism. We propose MUC4 expression as a predictive biomarker of trastuzumab efficacy and a guide to combination therapy of TNFα-blocking antibodies with trastuzumab. Clin Cancer Res; 23(3); 636-48. ©2016 AACR.

Stat3 regulates ErbB-2 expression and co-opts ErbB-2 nuclear function to induce miR-21 expression, PDCD4 downregulation and breast cancer metastasis

Membrane overexpression of the receptor tyrosine kinase ErbB-2 (MErbB-2) accounts for a clinically aggressive breast cancer (BC) subtype (ErbB-2-positive) with increased incidence of metastases. We and others demonstrated that nuclear ErbB-2 (NErbB-2) also plays a key role in BC and is a poor prognostic factor in ErbB-2-positive tumors. The signal transducer and activator of transcription 3 (Stat3), another player in BC, has been recognized as a downstream mediator of MErbB-2 action in BC metastasis. Here, we revealed an unanticipated novel direction of the ErbB-2 and Stat3 interaction underlying BC metastasis. We found that Stat3 binds to its response elements (GAS) at the ErbB-2 promoter to upregulate ErbB-2 transcription in metastatic, ErbB-2-positive BC. We validated these results in several BC subtypes displaying metastatic and non-metastatic ability, highlighting Stat3 general role as upstream regulator of ErbB-2 expression in BC. Moreover, we showed that Stat3 co-opts NErbB-2 function by recruiting ErbB-2 as its coactivator at the GAS sites in the promoter of microRNA-21 (miR-21), a metastasis-promoting microRNA (miRNA). Using an ErbB-2 nuclear localization domain mutant and a constitutively activated ErbB-2 variant, we found that NErbB-2 role as a Stat3 coactivator and also its direct role as transcription factor upregulate miR-21 in BC. This reveals a novel function of NErbB-2 as a regulator of miRNAs expression. Increased levels of miR-21, in turn, downregulate the expression of the metastasis-suppressor protein programmed cell death 4 (PDCD4), a validated miR-21 target. Using an in vivo model of metastatic ErbB-2-postive BC, in which we silenced Stat3 and reconstituted ErbB-2 or miR-21 expression, we showed that both are downstream mediators of Stat3-driven metastasis. Supporting the clinical relevance of our results, we found an inverse correlation between ErbB-2/Stat3 nuclear co-expression and PDCD4 expression in ErbB-2-positive primary invasive BCs. Our findings identify Stat3 and NErbB-2 as novel therapeutic targets to inhibit ErbB-2-positive BC metastasis.

Abstract 2265: Stat3 and ErbB-2 interaction in breast cancer metastasis

Metastasis is a complex multistep process, responsible for as much as 90% of cancer-related deaths, yet obtaining successful treatment for these patients remains an elusive challenge. It has long been recognized that the tyrosine kinase receptor ErbB-2 and the signal transducer and activator of transcription 3 (Stat3), two major players in the breast cancer (BC) scenario, are involved in BC metastatic dissemination through a mechanism where Stat3 acts as a downstream effector of ErbB-2 action. In addition, we and others have also disclosed the role of nuclear ErbB-2 (NErbB-2) in BC, whose presence we identified as a poor prognostic factor in MErbB-2-positive tumors. On the other hand, microRNAs are short non-coding endogenous RNAs with regulatory functions. In particular, high levels of microRNA-21 (miR-21), a well-known oncomiR, have been reported to actively promote invasion and metastasis in BC cell lines and tissues. Here, we describe a novel hierarchical interaction between Stat3, ErbB-2 and miR-21, underlying the metastatic phenotype of ErbB-2-positive BC. We disclosed that Stat3 acts as an upstream regulator of ErbB-2 expression and function. In a panel of cell lines corresponding to different BC subtypes we found that Stat3 induced ErbB-2 expression at the transcriptional level through its recruitment to response elements (called GAS) at the ErbB-2 promoter. Furthermore, we demonstrated that Stat3 co-opted NErbB-2 function, recruiting it as a coactivator, to assemble a transcriptional complex at the GAS sites of the miR-21 promoter, leading to miR-21 up-regulation. We showed that the increase in miR-21 levels resulted in the downregulation of the metastasis suppressor protein PDCD4, a well known miR-21 target. In order to assess the physiological relevance of our molecular findings, we developed an in vivo model of ErbB-2-overexpressing metastatic BC, in which Stat3 activation was inhibited by transfection with a Stat3 dominant negative variant (Stat3Y705F) or its expression was silenced by siRNAs. We demonstrated through reconstitution assays that ErbB-2 and miR-21 were necessary downstream mediators of Stat3-induced metastases development. Furthermore, we explored the clinical significance of our findings in a cohort of ErbB-2-positive primary invasive BC patients and demonstrated that Stat3 and ErbB-2 nuclear co-expression was associated with low PDCD4 expression levels, and that this correlated with the presence of nodal metastases. Our present results in experimental models and in the clinic shed light on the molecular mechanisms underlying BC metastasis and highlight targeting either Stat3 or NErbB-2 as novel therapeutic strategies for ErbB-2-positive BC patients.

#: 15-A-2849-AACR

Citation Format: Leandro Venturutti, Lucía V. Romero, Alejandro J. Urtreger, María F. Chervo, María F. Mercogliano, Rosalía I. Cordo Russo, Matías G. Pereyra, Gloria Inurrigarro, María C. Díaz Flaqué, Victoria Sunblad, Juan C. Roa, Pablo Guzmán, Elisa Bal de Kier-Joffe, Eduardo H. Charreau, Roxana Schillaci, Patricia V. Elizalde. Stat3 and ErbB-2 interaction in breast cancer metastasis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2265. doi:10.1158/1538-7445.AM2015-2265

Progesterone receptor activation downregulates GATA3 by transcriptional repression and increased protein turnover promoting breast tumor growth

Introduction

The transcription factor GATA3 is involved in mammary gland development and is crucial for the maintenance of the differentiated status of luminal epithelial cells. The role of GATA3 in breast cancer as a tumor suppressor has been established, although insights into the mechanism of GATA3 expression loss are still required.

Methods

Chromatin immunoprecipitation assays were conducted to study progestin modulation of recruitment of transcription factors to GATA3 promoter. We performed western blot and reverse RT-qPCR experiments to explore progestin regulation of GATA3 protein and mRNA expression respectively. Confocal microscopy and in vitro phosphorylation studies were conducted to examine progestin capacity to induce GATA3 serine phosphorylation in its 308 residue. GATA3 participation in progestin-induced breast cancer growth was addressed in in vitro proliferation and in vivo tumor growth experiments.

Results

In this study, we demonstrate that progestin-activated progesterone receptor (PR) reduces GATA3 expression through regulation at the transcriptional and post-translational levels in breast cancer cells. In the former mechanism, the histone methyltransferase enhancer of zeste homolog 2 is co-recruited with activated PR to a putative progesterone response element in the GATA3 proximal promoter, increasing H3K27me3 levels and inducing chromatin compaction, resulting in decreased GATA3 mRNA levels. This transcriptional regulation is coupled with increased GATA3 protein turnover through progestin-induced GATA3 phosphorylation at serine 308 followed by 26S proteasome-mediated degradation. Both molecular mechanisms converge to accomplish decreased GATA3 expression levels in breast cancer cells upon PR activation. In addition, we demonstrated that decreased GATA3 levels are required for progestin-induced upregulation of cyclin A2, which mediates the G1 to S phase transition of the cell cycle and was reported to be associated with poor prognosis in breast cancer. Finally, we showed that downregulation of GATA3 is required for progestin stimulation of both in vitro cell proliferation and in vivo tumor growth.

Conclusions

In the present study, we reveal that progestin-induced PR activation leads to loss of GATA3 expression in breast cancer cells through transcriptional and post-translational regulation. Importantly, we demonstrate that GATA3 downregulation is required for progestin-induced upregulation of cyclin A2 and for progestin-induced in vitro and in vivo breast cancer cell growth.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0491-x) contains supplementary material, which is available to authorized users.

Prostate cancer: identification with combined diffusion-weighted MR imaging and 3D 1H MR spectroscopic imaging--correlation with pathologic findings

PURPOSE

To retrospectively measure the mean apparent diffusion coefficient (ADC) with diffusion-weighted magnetic resonance (MR) imaging and the mean metabolic ratio (MET) with three-dimensional (3D) hydrogen 1 ((1)H) MR spectroscopic imaging in regions of interest (ROIs) drawn over benign and malignant peripheral zone (PZ) prostatic tissue and to assess ADC, MET, and combined ADC and MET for identifying malignant ROIs, with whole-mount histopathologic examination as the reference standard.

MATERIALS AND METHODS

The institutional review board approved this HIPAA-compliant retrospective study and issued a waiver of informed consent. From among 61 consecutive patients with prostate cancer, 38 men (median age, 61 years; range, 42-72 years) who underwent 1.5-T endorectal MR imaging before radical prostatectomy and who fulfilled all inclusion criteria of no prior hormonal or radiation treatment and at least one PZ lesion (volume, >0.1 cm(3)) at whole-mount pathologic examination were included. ADC maps were generated from diffusion-weighted MR imaging data, and MET maps of (choline plus polyamine plus creatine)/citrate were calculated from 3D (1)H MR spectroscopic imaging data. ROIs in the PZ identified by matching pathologic slides with T2-weighted images were overlaid on MET and ADC maps. Areas under the receiver operating characteristic curves (AUCs) were used to evaluate accuracy.

RESULTS

The mean ADC +/- standard deviation, (1.39 +/- 0.23) x 10(-3) mm(2)/sec, and mean MET (0.92 +/- 0.32) for malignant ROIs differed significantly from the mean ADC, (1.69 +/- 0.24) x 10(-3) mm(2)/sec, and mean MET (0.73 +/- 0.18) for benign ROIs (P < .001 for both). In distinguishing malignant ROIs, combined ADC and MET (AUC = 0.85) performed significantly better than MET alone (AUC = 0.74; P = .005) and was also better than ADC alone (AUC = 0.81), although the difference was not statistically significant (P = .09).

CONCLUSION

The combination of ADC and MET performs significantly better than MET for differentiating between benign and malignant ROIs in the PZ.