Prognostic value of HER2DX in early-stage HER2-positive breast cancer: a comprehensive analysis of 757 patients in the Sweden Cancerome Analysis Network-Breast dataset (SCAN-B)

BACKGROUND

The HER2DX risk-score has undergone rigorous validation in prior investigations involving patients with early-stage human epidermal growth factor receptor 2 (HER2)-positive (HER2+) breast cancer. In this study, we present the outcomes of the HER2DX risk-score within the most recent release of the Sweden Cancerome Analysis Network-Breast (SCAN-B) HER2+ cohort. This updated examination benefits from a larger patient sample, an extended follow-up duration, and detailed treatment information.

MATERIALS AND METHODS

Clinical and RNAseq data from the SCAN-B dataset were retrieved from Gene Expression Omnibus (GSE81538). Among the 6600 patients, 819 had HER2+ breast cancer, with 757 individuals with research-based HER2DX risk-scores and corresponding survival outcomes. The HER2DX risk-score was evaluated (i) as a continuous variable and (ii) using predefined cut-offs. The primary endpoint for this study was overall survival (OS). The Kaplan-Meier method and Cox models were used to estimate OS and a multistate model with four states was fitted to better characterize patients' follow-up.

RESULTS

The median follow-up time was 7.5 years (n = 757). The most common systemic therapy was chemotherapy with trastuzumab (82.0%) and most tumors were classified as T1-T2 (97.1%). The HER2DX risk-score as a continuous variable was significantly associated with OS after adjustment for clinical variables and treatment regimen [hazard ratios (HR) per 10-unit increment = 1.31, 95% confidence interval (CI) 1.13-1.51, P < 0.001] as well as within predefined risk groups (high versus low; HR = 2.57, 95% CI 1.36-4.85, P < 0.001). Patients classified as HER2DX high-risk also had higher risk of (i) breast cancer recurrence and (ii) death without previous recurrence. Within the subgroup of HER2+ T1N0 tumors (n = 297), those classified as high-risk demonstrated inferior OS compared to low-risk tumors (7-year OS 77.8% versus 96.8%, P < 0.001). The HER2DX mRNA ERBB2 score was associated with clinical HER2 status (area under the receiver operating characteristic curve = 0.91).

CONCLUSIONS

In patients with early-stage HER2+ breast cancer, HER2DX risk-score provides prognostic information beyond clinicopathological variables, including treatment regimen with or without trastuzumab.

Association of HER2DX with pathological complete response and survival outcomes in HER2-positive breast cancer

BACKGROUND

The HER2DX genomic test predicts pathological complete response (pCR) and survival outcome in early-stage HER2-positive (HER2+) breast cancer. Here, we evaluated the association of HER2DX scores with (i) pCR according to hormone receptor status and various treatment regimens, and (ii) survival outcome according to pCR status.

MATERIALS AND METHODS

Seven neoadjuvant cohorts with HER2DX and clinical individual patient data were evaluated (DAPHNe, GOM-HGUGM-2018-05, CALGB-40601, ISPY-2, BiOnHER, NEOHER and PAMELA). All patients were treated with neoadjuvant trastuzumab (n = 765) in combination with pertuzumab (n = 328), lapatinib (n = 187) or without a second anti-HER2 drug (n = 250). Event-free survival (EFS) and overall survival (OS) outcomes were available in a combined series of 268 patients (i.e. NEOHER and PAMELA) with a pCR (n = 118) and without a pCR (n = 150). Cox models were adjusted to evaluate whether HER2DX can identify patients with low or high risk beyond pCR status.

RESULTS

HER2DX pCR score was significantly associated with pCR in all patients [odds ratio (OR) per 10-unit increase = 1.59, 95% confidence interval 1.43-1.77; area under the ROC curve = 0.75], with or without dual HER2 blockade. A statistically significant increase in pCR rate due to dual HER2 blockade over trastuzumab-only was observed in HER2DX pCR-high tumors treated with chemotherapy (OR = 2.36 (1.09-5.42). A statistically significant increase in pCR rate due to multi-agent chemotherapy over a single taxane was observed in HER2DX pCR-medium tumors treated with dual HER2 blockade (OR = 3.11, 1.54-6.49). The pCR rates in HER2DX pCR-low tumors were ≤30.0% regardless of treatment administered. After adjusting by pCR status, patients identified as HER2DX low-risk had better EFS (P < 0.001) and OS (P = 0.006) compared with patients with HER2DX high-risk.

CONCLUSIONS

HER2DX pCR score and risk score might help identify ideal candidates to receive neoadjuvant dual HER2 blockade in combination with a single taxane in early-stage HER2+ breast cancer.

Patritumab Deruxtecan in Untreated Hormone Receptor-Positive/HER2-Negative Early Breast Cancer: Final Results from Part A of the Window-of-Opportunity SOLTI TOT-HER3 Pre-Operative Study

BACKGROUND

Patritumab deruxtecan (HER3-DXd) is a HER3-directed antibody-drug conjugate composed of a fully human anti-HER3 monoclonal antibody (patritumab) covalently linked to a topoisomerase I inhibitor payload via a stable, tumor-selective, tetrapeptide-based cleavable linker. TOT-HER3 is a window-of-opportunity study designed to assess the biological activity, measured by CelTIL score [ = -.8 × tumor cellularity (in %) + 1.3 × TILs (in %)], and clinical activity of HER3-DXd during short-term (21 days) pre-operative treatment in patients with primary operable HER2-negative early breast cancer.

PATIENTS AND METHODS

Patients with previously untreated hormone receptor (HR)-positive/HER2-negative tumors were allocated to one of four cohorts according to baseline ERBB3 mRNA expression. All patients received one dose of HER3-DXd 6.4 mg/kg. The primary objective was to evaluate change from baseline in CelTIL score.

RESULTS

Seventy-seven patients were evaluated for efficacy. A significant change in CelTIL score was observed, with a median increase from baseline of 3.5 (interquartile range, -3.8 to 12.7; P=.003). Among patients evaluable for clinical response (n=62), an overall response rate of 45% was observed (tumor measurement by caliper), with a trend toward an increase in CelTIL score among responders compared with non-responders (mean difference, +11.9 vs +1.9). Change in CelTIL score was independent of baseline ERBB3 mRNA and HER3 protein levels. Genomic changes occurred, including switching toward a less proliferative tumor phenotype based on PAM50 subtypes, suppression of cell proliferation genes, and induction of genes associated with immunity. Treatment-emergent adverse events were observed in 96% of patients (14% grade ≥3); most common were nausea, fatigue, alopecia, diarrhea, vomiting, abdominal pain, and neutrophil count decrease.

CONCLUSIONS

A single dose of HER3-DXd was associated with clinical response, increased immune infiltration, suppression of proliferation in HR-positive/HER2-negative early breast cancer, and a tolerable safety profile consistent with previously reported results. These findings support further study of HER3-DXd in early breast cancer.

Prognostic value of intrinsic subtypes in hormone-receptor-positive metastatic breast cancer: systematic review and meta-analysis

BACKGROUND

In hormone receptor-positive (HoR+) breast cancer (BC), gene expression analysis identifies luminal A (LumA), luminal B (LumB), human epidermal growth factor receptor 2 (HER2)-enriched (HER2-E), basal-like (BL) intrinsic subtypes and a normal-like group. This classification has an established prognostic value in early-stage HoR+ BC. Here, we carried out a trial-level meta-analysis to determine the prognostic ability of subtypes in metastatic BC (MBC).

MATERIALS AND METHODS

We systematically reviewed all the available prospective phase II/III trials in HoR+ MBC where subtype was assessed. The primary endpoint was progression-free survival (PFS)/time to progression (TTP) of the LumA subtype compared to non-LumA. Secondary endpoints were PFS/TTP of each individual subtype, according to treatment, menopausal and HER2 status and overall survival (OS). The random-effect model was applied, and heterogeneity assessed through Cochran's Q and I². Threshold for significance was set at P < 0.05. The study was registered in PROSPERO (ID: CRD42021255769).

RESULTS

Seven studies were included (2536 patients). Non-LumA represented 55.2% and was associated with worse PFS/TTP than LumA [hazard ratio (HR) 1.77, P < 0.001, I² = 61%], independently of clinical HER2 status [P_{subgroup difference} (P_sub) = 0.16], systemic treatment (P_sub = 0.96) and menopausal status (P_sub = 0.12). Non-LumA tumors also showed worse OS (HR 2.00, P < 0.001, I² = 65%), with significantly different outcomes for LumB (PFS/TTP HR 1.46; OS HR 1.41), HER2-E (PFS/TTP HR 2.39; OS HR 2.08) and BL (PFS/TTP HR 2.67; OS HR 3.26), separately (PFS/TTP P_sub = 0.01; OS P_sub = 0.005). Sensitivity analyses supported the main result. No publication bias was observed.

CONCLUSIONS

In HoR+ MBC, non-LumA disease is associated with poorer PFS/TTP and OS than LumA, independently of HER2, treatment and menopausal status. Future trials in HoR+ MBC should consider this clinically relevant biological classification.

Immune microenvironment characterisation and dynamics during anti-HER2-based neoadjuvant treatment in HER2-positive breast cancer

Despite their recognised role in HER2-positive (HER2+) breast cancer (BC), the composition, localisation and functional orientation of immune cells within tumour microenvironment, as well as its dynamics during anti-HER2 treatment, is largely unknown. We here investigate changes in tumour-immune contexture, as assessed by stromal tumour-infiltrating lymphocytes (sTILs) and by multiplexed spatial cellular phenotyping, during treatment with lapatinib-trastuzumab in HER2+ BC patients (PAMELA trial). Moreover, we evaluate the relationship of tumour-immune contexture with hormone receptor status, intrinsic subtype and immune-related gene expression. sTIL levels increase after 2 weeks of HER2 blockade in HR-negative disease and HER2-enriched subtype. This is linked to a concomitant increase in cell density of all four immune subpopulations (CD3+, CD4+, CD8+, Foxp3+). Moreover, immune contexture analysis showed that immune cells spatially interacting with tumour cells have the strongest association with response to anti-HER2 treatment. Subsequently, sTILs consistently decrease at the surgery in patients achieving pathologic complete response, whereas most residual tumours at surgery remain inflamed, possibly reflecting a progressive loss of function of T cells. Understanding the features of the resulting tumour immunosuppressive microenvironment has crucial implications for the design of new strategies to de-escalate or escalate systemic therapy in early-stage HER2+ BC.

De-escalated therapy for HR+/HER2+ breast cancer patients with Ki67 response after 2-week letrozole: results of the PerELISA neoadjuvant study

BACKGROUND

In human epidermal growth factor receptor 2 (HER2+) breast cancers, neoadjuvant trials of chemotherapy plus anti-HER2 treatment consistently showed lower pathologic complete response (pCR) rates in hormone receptor (HR) positive versus negative tumors. The PerELISA study was aimed to evaluate the efficacy of a de-escalated, chemotherapy-free neoadjuvant regimen in HR+/HER2+ breast cancer patients selected on the basis of Ki67 inhibition after 2-week letrozole.

PATIENTS AND METHODS

PerELISA is a phase II, multicentric study for postmenopausal patients with HR+/HER2+ operable breast cancer. Patients received 2-week letrozole, and then underwent re-biopsy for Ki67 evaluation. Patients classified as molecular responders (Ki67 relative reduction >20% from baseline) continued letrozole and started trastuzumab-pertuzumab for five cycles. Patients classified as molecular non-responders started weekly paclitaxel for 13 weeks combined with trastuzumab-pertuzumab. Primary aim was breast and axillary pCR. According to a two-stage Simon's design, to reject the null hypothesis, at least 8/43 pCR had to be documented.

RESULTS

Sixty-four patients were enrolled, 44 were classified as molecular responders. All these patients completed the assigned treatment with letrozole-trastuzumab-pertuzumab and underwent surgery. A pCR was observed in 9/44 cases (20.5%, 95% confidence interval 11.1% to 34.5%). Among molecular non-responders, 16/17 completed treatment and underwent surgery, with pCR observed in 81.3% of the cases. PAM50 intrinsic subtype was significantly associated with Ki67 response and pCR. Among molecular responders, the pCR rate was significantly higher in HER2-enriched than in other subtypes (45.5% versus 13.8%, P = 0.042).

CONCLUSIONS

The primary end point of the study was met, by reaching the pre-specified pCRs. In patients selected using Ki67 reduction after short-term letrozole exposure, a meaningful pCR rate can be achieved without chemotherapy. PAM50 intrinsic subtyping further refines our ability to identify a subset of patients for whom chemotherapy might be spared.

EUDRACT NUMBER

2013-002662-40.

CLINICALTRIALS.GOV IDENTIFIER

NCT02411344.

Association between PD1 mRNA and response to anti-PD1 monotherapy across multiple cancer types

Background

We hypothesized that the abundance of PD1 mRNA in tumor samples might explain the differences in overall response rates (ORR) observed following anti-PD1 monotherapy across cancer types.

Patients and methods

RNASeqv2 data from 10 078 tumor samples representing 34 different cancer types was analyzed from TCGA. Eighteen immune-related gene signatures and 547 immune-related genes, including PD1, were explored. Correlations between each gene/signature and ORRs reported in the literature following anti-PD1 monotherapy were calculated. To translate the in silico findings to the clinical setting, we analyzed the expression of PD1 mRNA using the nCounter platform in 773 formalin-fixed paraffin embedded (FFPE) tumor samples across 17 cancer types. To test the direct relationship between PD1 mRNA, PDL1 immunohistochemistry (IHC), stromal tumor-infiltrating lymphocytes (sTILs) and ORR, we evaluated an independent FFPE-based dataset of 117 patients with advanced disease treated with anti-PD1 monotherapy.

Results

In pan-cancer TCGA, PD1 mRNA expression was found strongly correlated (r > 0.80) with CD8 T-cell genes and signatures and the proportion of PD1 mRNA-high tumors (80th percentile) within a given cancer type was variable (0%-84%). Strikingly, the PD1-high proportions across cancer types were found strongly correlated (r = 0.91) with the ORR following anti-PD1 monotherapy reported in the literature. Lower correlations were found with other immune-related genes/signatures, including PDL1. Using the same population-based cutoff (80th percentile), similar proportions of PD1-high disease in a given cancer type were identified in our in-house 773 tumor dataset as compared with TCGA. Finally, the pre-established PD1 mRNA FFPE-based cutoff was found significantly associated with anti-PD1 response in 117 patients with advanced disease (PD1-high 51.5%, PD1-intermediate 26.6% and PD1-low 15.0%; odds ratio between PD1-high and PD1-intermediate/low = 8.31; P < 0.001). In this same dataset, PDL1 tumor expression by IHC or percentage of sTILs was not found associated with response.

Conclusions

Our study provides a clinically applicable assay that links PD1 mRNA abundance, activated CD8 T-cells and anti-PD1 efficacy.

A predictive model of pathologic response based on tumor cellularity and tumor-infiltrating lymphocytes (CelTIL) in HER2-positive breast cancer treated with chemo-free dual HER2 blockade

Background

The presence of stromal tumor-infiltrating lymphocytes (TILs) is associated with increased pathologic complete response (pCR) and improved outcomes in HER2-positive early-breast cancer (BC) treated with anti-HER2-based chemotherapy. In the absence of chemotherapy, the association of TILs with pCR following anti-HER2 therapy-only is largely unknown.

Patients and methods

The PAMELA neoadjuvant trial treated 151 women with HER2-positive BC with lapatinib and trastuzumab [and hormonal therapy if hormone receptor (HR)-positive] for 18 weeks. Percentage of TILs and tumor cellularity were determined at baseline (N = 148) and at day 15 (D15) of treatment (N = 134). Associations of TILs and tumor cellularity with pCR in the breast were evaluated. A combined score based on tumor cellularity and TILs (CelTIL) measured at D15 was derived in PAMELA, and validated in D15 samples from 65 patients with HER2-positive disease recruited in the LPT109096 neoadjuvant trial, where anti-HER2 therapy-only was administer for 2 weeks, then standard chemotherapy was added for 24 weeks.

Results

In PAMELA, baseline and D15 TILs were significantly associated with pCR in univariate analysis. In multivariable analysis, D15 TILs, but not baseline TILs, were significantly associated with pCR. At D15, TILs and tumor cellularity were found independently associated with pCR. A combined score (CelTIL) taking into account both variables was derived. CelTIL at D15 as a continuous variable was significantly associated with pCR, and patients with CelTIL-low and CelTIL-high scores had a pCR rate of 0% and 33%, respectively. In LPT109096, CelTIL at D15 was found associated with pCR both as a continuous variable and as group categories using a pre-defined cut-off (75.0% versus 33.3%).

Conclusions

On-treatment TILs, but not baseline TILs, are independently associated with response following anti-HER2 therapy-only. A combined score of TILs and tumor cellularity measured at D15 provides independent predictive information upon completion of neoadjuvant anti-HER2-based therapy.

Clinical trial number

NCT01973660.

Abstract P6-17-07: Gene signatures and subtype changes during HER2 dual blockade in PAM50 HER2-enriched HER2-positive breast cancer

Background: HER2-positive (HER2+) breast cancer (BC) is composed of 4 molecular subtypes: Luminal A and B, HER2-enriched (HER2-E) and Basal-like. Among them, the HER2-E is highly sensitive to anti-HER2 treatment. However, ˜60% of HER2-E tumors do not achieve a pathological complete response (pCR) following neoadjuvant dual HER2 blockade without chemotherapy. Here, we aimed to better understand the molecular changes of the HER2-E subtype during anti-HER2 treatment.

Methods: Gene expression was evaluated in 101 patients with HER2-E tumors from the PAMELA neoadjuvant phase II trial (Lancet Oncol 2017). Briefly, women with HER2+ BC were treated with lapatinib and trastuzumab (and hormonal therapy if hormone receptor [HR]-positive) for 18 weeks. The median time between the last dose of treatment and surgery was 35 days (range=213; interquartile range=16). Expression of the PAM50 genes and 6 PAM50 signatures (Luminal A, Luminal B, HER2-E, Basal-like, normal-like and the PAM50 proliferation score) were determined using the nCounter platform at baseline (n=101), after 2 weeks of treatment (n=96) and in residual tumors (non-pCR) at surgery (n=57). Same analyses were done in 2 HER2+/HER2-E cell line models (BT474 [HR+] and SKBR3 [HR-]) following in vitro treatment with trastuzumab in combination with lapatinib. Biological changes between 2 time-points were determined by paired t-tests with a false discovery rate (FDR) &lt;5%.

Results: After 2 weeks of treatment, 85.7% and 94.6% of the 56 genes/signatures were found differentially expressed (FDR&lt;5%) in HER2-E/HR+ (n=35) and HER2-E/HR- (n=61) tumors, respectively. The two gene lists were highly correlated (correlation coefficient=0.93). Overall, a significant relative increase in Luminal A and normal-like signature scores, and a relative decrease in proliferation, HER2-E and Luminal B signature scores, were observed between baseline and week 2. Interestingly, a PAM50 subtype switch to Luminal A was observed in 31.6% and 4.8% of HER2-E/HR+ and HER2-E/HR- tumors. In BT474 and SKBR3, all genes/signatures were also found differentially expressed (FDR&lt;5%) following 72h of dual HER2 blockade. The in vitro findings recapitulated the in vivo findings in 80-86% of the genes/signatures. Similar to tumors, a switch to a Luminal A subtype following dual HER2 blockade was observed in BT474 but not in SKBR3. Finally, 92.9% of the 56 genes/signatures were found differentially expressed (FDR&lt;5%) in residual tumors at surgery compared to week 2. Contrary to the findings in the first 2 weeks of treatment, a general rebound effect in gene expression was observed between week 2 and surgery. Similarly, a rebound effect was observed in 60% of the genes/signatures in BT474 after removing anti-HER2 therapy for 72h, leading to a subtype switch from Luminal A back to HER2-E.

Conclusions: Dual HER2 blockade in the HER2-E subtype induces large biological changes that lead to a more low-proliferative Luminal A phenotype both in tumors and in vitro models, especially in HER2-E/HR+ disease. These phenotypic changes are reversible upon stopping anti-HER2 treatment. This finding supports the use of maintenance anti-HER2 treatment +/- endocrine therapy (if HR+) in advanced HER2+ BC.

Citation Format: Brasó-Maristany F, Griguolo G, Llombart-Cussac A, Pascual T, Paré L, Bermejo B, Oliveira M, Morales S, Martinez N, Vidal M, Pernas S, Lopez R, Muñoz M, Galvan P, Garau I, Manso L, Alarcón J, Martínez E, Villagrasa P, Cortés J, Prat A. Gene signatures and subtype changes during HER2 dual blockade in PAM50 HER2-enriched HER2-positive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-07.

Abstract P6-17-05: Independent validation of a combined biomarker based on the PAM50 HER2-enriched subtype and ERBB2 mRNA levels following HER2 blockade without chemotherapy in the PerELISA phase II trial

Background: A combined biomarker based on HER2-enriched subtype (HER2-E) and ERBB2 mRNA predicts response and survival in HER2+ breast cancer following trastuzumab +/- lapatinib in the absence of chemotherapy (Prat et al. ASCO 2018). Here, we tested the ability of the combined biomarker to predict pathological complete response (pCR) following neoadjuvant trastuzumab, pertuzumab and endocrine therapy.

Methods: RNA from 40 baseline tumor samples from the phase II PerELISA trial were evaluated. PerELISA evaluated the efficacy of a de-escalated, chemotherapy-free neoadjuvant regimen based on dual HER2 blockade with trastuzumab and pertuzumab in combination with letrozole in HER2+/hormone receptor-positive breast cancer selected on the basis of Ki67 response after short course letrozole-alone (Guarneri ASCO 2018). Ki67 response was defined by protocol as relative Ki67 reduction ≥20% from baseline at day 14. Gene-expression was measured using the nCounter platform. Intrinsic subtypes and ERBB2 levels were determined by the PAM50 gene expression predictor. A pre-specified ERBB2 cutoff was determined to define ERBB2-high. Univariate and multivariable logistic regression analyses were performed.

Results: The proportion of HER2-E disease within the ERBB2-high and ERBB2-low groups was 46.2% (6/13) and 18.5% (5/27), respectively. The discordance rate at the individual level was 30% (12/40). A total of 6 (15%) and 34 (85%) samples were HER2-E/ERBB2-high and others, respectively. The magnitude of Ki67 reduction of the HER2-E/ERBB2-high and others groups was 64.8% and 63.2%, respectively (p=0.88). The pCR rate of HER2-E/ERBB2-high was 66.7%. The pCR rate of the others group was 14.7%. The univariate odds ratio between HER2-E/ERBB2-high tumors and the others groups was 11.60 (95% CI 1.66-81.10; p=0.014). No other clinical-pathological variable was significantly associated with pCR.

Conclusion: The combined HER2-E/ERBB2-high biomarker can identify patients who might be good candidates to receive dual HER2 blockade alone without chemotherapy.

Citation Format: Prat A, Griguolo G, Dieci MV, Bisagni G, Frassoldati A, Bianchi GV, Pascual T, Pare L, Galvan P, Urso L, Conte P, Guarneri V. Independent validation of a combined biomarker based on the PAM50 HER2-enriched subtype and ERBB2 mRNA levels following HER2 blockade without chemotherapy in the PerELISA phase II trial [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 P6-17-05.

Abstract P6-17-08: Dynamics of tumor-infiltrating lymphocytes (TILs) during neoadjuvant dual HER2 blockade in HER2-positive (HER2+) breast cancer in the absence of chemotherapy

Background: TILs in HER2+ breast cancer (BC) predict 1) prognosis in early setting, 2) complete pathological response (pCR) following neoadjuvant antiHER2-based therapy and 3) response to trastuzumab and pembrolizumab in the metastatic setting. However, less is known regarding changes in TILs during antiHER2-based treatment.

Methods: Stromal TILs where evaluated centrally using H/E slides in tumor samples from the PAMELA (NCT01973660) neoadjuvant phase II trial. Briefly, 151 women with HER2+ BC were treated with lapatinib and trastuzumab, and hormonal therapy if HR positive, for 18 weeks. TIL levels were determined at baseline (n=148), after 2 weeks of treatment (n=134) and at surgery (n=137). Expression of 560 genes, including immune-related genes (e.g. CD8A, CD4, PD1 and PDL1) was measured at the same timepoints (baseline n=151, 2-weeks n=144, surgery n=144) using the nCounter platform. Intrinsic subtyping at baseline was determined using the PAM50 gene expression predictor. Changes in TILs between 2 time-points were determined by paired t-tests. Correlation of TILs with gene expression was assessed by quantitative SAM analysis using a False Discovery Rate &lt;1%. All statistical tests were two-sided and considered significant when p&lt;0.05. All statistical analyses were carried out using the R software.

Results: Compared to baseline, a significant increase in TILs was observed at week 2 in HR- (p&lt;0.001) and HER2-enriched (HER2-E) tumors (p=0.001), but not in HR+ (p=0.133) and non-HER2-E tumors (p=0.067). Within HR- and HER2-E tumors, increase in TILs at week 2 from baseline was observed regardless of pathological response at surgery (pCR and HR- [p=0.008]; RD and HR- [p=0.037]; pCR and HER2-E [p=0.010]; RD and HER2-E [p=0.056]). Compared to week 2, a significant decrease in TILs at surgery was observed in HR- (p=0.002) and HER2-E (p=0.003) tumors, but not in HR+ (p=0.616) and non-HER2-E tumors (p=0.578). Within HR- and HER2-E tumors, a significant decrease in TILs between week 2 and surgery was observed in tumors achieving pCR (p=0.004 and p=0.005), while, in tumors not achieving pCR, no significant tendency was observed (26.4% and 33.0% of tumors showed an increase and a decrease of TILs between week 2 and surgery). Nonetheless, the vast majority of residual tumors (non-pCR) at surgery had TILs above ≥5%: 34.3% 5-10%, 21.0% 10-20%, 15.2% 20-40% and 11.4% ≥40%. Finally, TILs scoring was found highly enriched (FDR&lt;1%) for immune-related genes tracking activated CD8 T-cells (i.e. CD8A, CD3G, LAG3 and PD1). Expression of these immune genes consistently correlated with TIL levels across the 3 time-points.

Conclusions: In early HER2+ BC, a general increase in TILs is observed following 2 weeks of dual HER2 blockade. This observation is mostly observed in HR- and HER2-E subtype, but regardless of pathological response at surgery. After 2 weeks of treatment, TILs consistently decrease in patients achieving a pCR, whereas two main patterns of TILs expression are observed in patients with residual disease at surgery. Nonetheless, most residual tumors at surgery are inflamed (i.e. TILs ≥5%) and might be good candidates for clinical trials evaluating adjuvant immune checkpoint inhibitors.

Citation Format: Griguolo G, Holgado E, Cortés J, Fasani R, Pascual T, Paré L, Bermejo B, Oliveira M, Morales S, Martinez N, Vidal M, Pernas S, Lopez R, Muñoz M, Galvan P, Garau I, Manso L, Alarcón J, Martínez E, Villagrasa P, LLombart-Cussac A, Prat A, Nuciforo P. Dynamics of tumor-infiltrating lymphocytes (TILs) during neoadjuvant dual HER2 blockade in HER2-positive (HER2+) breast cancer in the absence of chemotherapy [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 P6-17-08.

Abstract OT3-02-05: CORALLEEN: A phase 2 clinical trial of chemotherapy or letrozole plus ribociclib as neoadjuvant treatment for postmenopausal patients with luminal B/HER2-negative breast cancer

Background: Dysregulation of cyclin D-CDK4/6-Rb pathway is associated with endocrine resistance in hormone receptor–positive (HR+) breast cancer. Recently, a CDK4/6 inhibitor has shown unprecedented efficacy in metastatic disease, leading to its regulatory approval. Several others are currently in clinical development for the management of HR+ breast cancer in the early and advanced settings. However, it is vital to gain insights into the molecular and biological effects of this class of agents and could identify patients who can benefit the most, delaying or avoiding the use of chemotherapy.The neoadjuvant setting provides an ideal scenario to carry out these investigations. Hence, we propose to conduct an exploratory study to evaluate the biological effects and the efficacy of ribociclib in patients with primary luminal B tumors. We hypothesize that the combination of ribociclib plus letrozole may offer clinical benefit in the preoperative setting. Methods: This is a parallel, multicenter, two-arm, randomized exploratory study in postmenopausal women with primary operable HR+/HER2-negative Luminal B breast cancer designed to evaluate the clinical benefit of ribociclib plus letrozole. Eligibility includes stage I-III operable breast cancer, Luminal B by PAM50, ECOG 0-1. They will be randomized 1:1 to receive either six 28-days cycles of ribociclib (600mg; 3-weeks-on/1-week-off) plus daily letrozole (2.5mg) or chemotherapy: four cycles of AC (doxorubicin 60 mg/m2, cyclophosphamide 600 mg/m2 every 21 days) followed by weekly paclitaxel during 12 weeks. Baseline, Day 15 on-treatment, and surgical specimens will be collected for molecular characterization and evaluation of response (decrease in Ki67, change to ROR low disease) The primary endpoint is the rate of Residual Cancer Burden (RCB) per MD Anderson Cancer Center procedures. A rate of RCB 0 and 1 score at surgery, with a rank between 20% to 25% with 47 evaluable patients by group of treatment will offer a precision between 11.5% and 12.4%, respectively (95%CI). Ninety-four patients will be enrolled in 21 sites across Spain. The trial was activated in July 2017. As of June 2018, 78 patients have been recruited.

Citation Format: Gavila J, Saura C, Oliveira M, Ciruelos E, Gonzalez X, de la Peña L, Bermejo de las Heras B, Muñoz M, Fernandez P, Villagrasa P, Ortega V, Lopez R, Celiz P, Pascual T, Prat A. CORALLEEN: A phase 2 clinical trial of chemotherapy or letrozole plus ribociclib as neoadjuvant treatment for postmenopausal patients with luminal B/HER2-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 OT3-02-05.

Abstract P5-11-04: Anti-proliferative effect of oral metronomic vinorelbine (mVNB) in PAM50 Luminal/HER2-negative early breast cancer (SOLTI-1501 VENTANA): A randomized, three-arm, window-of-opportunity study

BACKGROUND: The anti-proliferative effect of mVNB alone or in combination with endocrine therapy in patients with hormone receptor-positive/HER2- breast cancer (BC) has been scarcely addressed.

METHODS: Postmenopausal women with untreated stage I-III BC were randomized (1:1:1) to receive 3 weeks of letrozole (LTZ) 2.5mg/day, oral mVNB 50mg 3 days/week or the combination. The 1ary objective was to evaluate, within PAM50 Luminal A/B disease, if the anti-proliferative effect of mVNB+LTZ was superior to monotherapy. An anti-proliferative effect was defined as the mean relative decrease of the PAM50 11-gene Proliferation Score in each arm. 2ary objectives included safety and the comparison of the anti-proliferative effect between arms. An unplanned analysis of stromal tumor infiltrating lymphocytes (sTILs) was performed. PAM50 analyses were performed using the nCounter®-based Breast Cancer 360TM panel. Changes in the expression of 790 genes/signatures tracking multiple biological processes from tumor cells and the microenvironment were evaluated within each arm using paired (surgery vs. baseline) univariate analyses. P-values were corrected for multiple comparisons using false discovery rate (FDR).

RESULTS: A total of 61 patients were randomized and 54 paired samples (89%) were analyzed. Main patient characteristics were mean age 67, mean tumor size 1.7 cm, stage I (55.7%) and grade 1-2 (90%). Grade 3 toxicities occurred in 3.3% of cases. Baseline samples were Luminal A (72.3%) or B (27.7%). The anti-proliferative effect of mVNB+LTZ (-73.2%) was superior to both monotherapy arms combined (-49.9%; p=0.001) and mVNB (-19.1%; p&lt;0.001). The anti-proliferative effect of mVNB+LTZ (-73.2%) was higher compared to LTZ (-65.7%) but did not reach statistical significance (p=0.328). Across the mVNB+LTZ, LTZ and VNB arms, 413 (52.3%), 403 (51.0%) and 21 (2.6%) genes/signatures were found differentially expressed (FDR&lt;5%) between baseline and surgery samples. Compared to mVNB+LTZ baseline samples, surgical samples showed higher expression of AP-1 transcription factor subunits FOS and JUN, inflammatory chemokines (e.g. CCL4 and IL6), stromal-related genes (e.g. CAV1 and stroma signature) and immune infiltration (e.g. CD8 T-cell signature) and lower expression of proliferation-related genes (e.g. MKI67 and UBE2C), estrogen receptor-signaling and Risk of Recurrence. Of the 413 genes found differentially expressed in surgical samples compared to baseline samples in the mVNB+LTZ arm, 108 (26.2%) were not found in the LTZ arm. Among them, high expression of LAG3, CD24, CD84 and CCR5. Under the microscope, sTILs (≥10% at week 3) were observed in 6.6% (mVNB), 15% (LTZ) and 26% (mVNB+LTZ) of the cases. In tumors with ≤10% TILs at baseline, an increase in TILs was observed following LTZ (p=0.049) and mVNB+LTZ (p=0.012).

CONCLUSIONS: mVNB is well-tolerated and presents antiproliferative activity alone and in combination with LTZ. The increase of activated CD8 T-cells or TILs observed with LTZ+mVNB opens the possibility of studying combinations with immunotherapy. Further investigation comparing these biological results with other metronomic schedules or combinations is warranted.

Citation Format: Prat A, Adamo B, Pascual T, Perez Fidalgo JA, Blanch S, Martínez N, Gomez Pardo P, Lopez Gonzalez A, Murillo Jaso L, Amillano K, Vidal M, Paré L, Canes J, Galvan P, Gonzalez Farre B, Ortega Cebrián V, Gonzalez X, Bellet Ezquerra M, Villagrasa P, Ciruelos E. Anti-proliferative effect of oral metronomic vinorelbine (mVNB) in PAM50 Luminal/HER2-negative early breast cancer (SOLTI-1501 VENTANA): A randomized, three-arm, window-of-opportunity study [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 P5-11-04.

The IAEA Human Health Campus: Online Educational Resource for Health Care Professionals in Radiation Medicine

Background: Cognizant of the educational needs of the member states, and taking advantage of the current technological advances in this digital age, the International Atomic Energy Agency (IAEA) officially launched in 2010 the Human Health Campus (HHC; http://humanhealth.iaea.org ), which is an online educational resource initiative geared toward enhancing professional knowledge of health professionals in radiation medicine. Aim: Determine how and by whom the IAEA HHC is being visited and used since its inception in October 2010. Methods: Using the information provided by Google Analytics, determine the overall key performance indicators (KPIs) such as total sessions, total users, total page views, session duration, including daily number of visits to the HHC, county of origin, evaluation of the most popular sections and source of the traffic. Results: Since its launch on October 6th, 2010, KPIs are as follows: total sessions 374,279, total users 243,195, total page views 1,393,310, pages/session 3.72, average session duration 00:03:08. % of new sessions 64.92%. The HHC has witnessed continual growth year on year (YoY) in total sessions (visits) since its inception in October 2010, and total users. For 2016 (the highest performing year so far) there were 201 visits/day, 40% increase in traffic YoY and 20% user growth. Traffic to the Webinar content has seen sustained growth in the number of YoY since being introduced to the HHC in 2013. 2016 saw the largest increase of over +600%. E-Learning modules have also seen growth in the traffic YoY since being introduced to the HHC in 2011. The year 2015 saw a large increase in total traffic with over +95%. E-Learning traffic accounts for almost 25% of all traffic to the Nuclear Medicine section. Visits by mobile devices have increased YoY exponentially since the launch of the HHC, with the mobile traffic growing strong through 2015-2016 with an increase of 5482 sessions, or an 81% uplift YoY. For 2017, it represented 18% of the total traffic (from 3% in 2012). There is a clear prevalence of desktop users (85.5%), as the preferred method of browsing the HHC. A total of 210 countries and overseas territories have visited the HHC. The United States is the largest contributor of traffic from a global perspective with 16.31% of total traffic, almost double the next largest which is the UK with 9.10%. India with 5.45% and Australia with 3.27% of total traffic, respectively, round out the top 4. Not surprisingly, more than 60% of users are from English-speaking countries. Spanish is the second most popular language of users with just over 6% of total traffic. Conclusion: The HHC is an IAEA open access Web based educational resource for professionals in the field of radiation medicine being visited by as many as 210 countries. The upward trend in its use suggests that the IAEA HHC will continue to be an important player in providing educational resources for professionals worldwide.

Abstract P2-09-14: A predictive model of pathological response following dual HER2 blockade-only based on tumor cellularity and tumor-infiltrating lymphocytes (CelTIL) in HER2-positive breast cancer

Background: Increased number of tumor-infiltrating lymphocytes (TILs) at baseline is associated with pathological complete response (pCR) and improved outcomes in HER2-positive early breast cancer treated with anti-HER2-based chemotherapy. In the absence of chemotherapy, the association of TILs with pCR following anti-HER2 therapy-only is currently unknown.

Methods: The PAMELA (NCT01973660)neoadjuvant trial treated 151 women with HER2-positive breast cancer with lapatinib and trastuzumab (and hormonal therapy if hormone receptor-positive) for 18 weeks. Percentage of TILs and tumor cellularity were determined at baseline (n=148) and after 2 weeks of treatment (n=134). Associations of TILs and tumor cellularity with pCR in the breast were evaluated using univariate and multivariable logistic regression models. The regression coefficients were used to derive a score based on TILs and tumor cellularity measured at week 2 (CelTIL) was derived in PAMELA,and tested in week 2 samples from 65 patients with HER2+ disease recruited in the LPT109096 (NCT00524303) phase 2 neoadjuvant trial, where anti-HER2 therapy-only (trastuzumab, lapatinib or the combination) was administered for 2 weeks, followed by the addition of standard multi-agent chemotherapy for 24 weeks.

Results: In PAMELA, at baseline, TILs were significantly associated with pCR in univariate analysis but not in multivariable analysis (adjusted odds ratio [OR]=1.01, 0.98-1.03; p-value=0.620). A statistically significant increase in TILs was observed at week 2 compared to baseline (mean difference +6.9%; p-value&lt;0.001). At week 2, TILs were significantly associated with pCR in univariate and multivariable analyses (adjusted OR=1.04, 1.01-1.06; p-value=0.009). TILs and tumor cellularity at week 2 were independently associated with pCR and a combined score (from 0 to 100) taking into account both variables was derived. CelTIL as a continuous variable was significantly associated with pCR, and patients with CelTIL-low and CelTIL-high scores (cutoff &lt; 33.59) had a pCR rate of 0% and 33%, respectively. Independent validation of CelTIL in week 2 samples from 65 patients with HER2+ disease recruited in the LPT109096 phase 2 neoadjuvant trial will be presented at the conference.

Conclusions: A combined score of TILs and tumor cellularity at week 2 following anti-HER2 therapy-only is associated with pCR upon completion of neoadjuvant anti-HER2-based therapy.

Citation Format: Nuciforo P, Holgado E, Llombart A, Fasani R, Paré L, Pascual T, Oliveira M, Martínez N, Bermejo B, Vidal M, Pernas S, López R, Muñoz M, Garau I, Manso L, Alarcón J, Martínez E, Villagrasa P, Cortés J, Prat A. A predictive model of pathological response following dual HER2 blockade-only based on tumor cellularity and tumor-infiltrating lymphocytes (CelTIL) in HER2-positive breast cancer [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 P2-09-14.

Abstract P2-09-11: PAM50 intrinsic subtyping as a predictor of pathological complete response to neoadjuvant trastuzumab-based chemotherapy in early HER2-positive breast cancer

Background: HER2-positive breast cancer (BC) is a heterogeneous disease from a clinical and biological perspective. Intrinsic subtype defined by gene expression has an important role in determining response to treatment, as seen in several neoadjuvant trials (e.g. CALGB40601, CherLOB, NeoALTTO and PAMELA). However, limited data exist in an off-trial setting. The objective of this study was to evaluate the association of intrinsic subtypes with pathological completed response (pCR) and survival outcomes of a series of HER2-positive patients (pts) homogeneously treated with trastuzumab-based primary chemotherapy (PC) in a single comprehensive cancer center.

Methods: Clinical-pathological data were evaluated in a series of 150 consecutive stage II-IIIC (T4d included) HER2-positive BC pts treated in ICO-Hospitalet (Spain) from August-2009 to December-2012 with weekly paclitaxel x12 followed by FEC/3w x 4 and concurrent trastuzumab for a total of 24w. HER2-positivity was considered according to ASCO-CAP 2007 guidelines. pCR was defined as ypT0/isypN0. The expression of 105 BC-related genes, including the PAM50 genes, was determined in baseline and residual formalin-fixed paraffin-embedded tumor samples using the nCounter platform. Intrinsic subtypes were determined by the research-based PAM50 gene expression predictor. Association of variables with pCR or disease-free survival (DFS) was evaluated using logistic regression analyses and cox proportional hazard models.All statistical tests were two-sided and considered significant when p≤0.05.

Results: Most pts had T2 (64%) and T4 (20%) tumors and clinically node-positive disease (77%). 53% had hormonal receptor (HR)+ disease. 84 of the 150pts (56%) achieved a pCR; HR-neg was associated with higher pCR rates (72.5%vs 42% in HR+ P&lt;0.001). 90 of the 150 (60%) baseline samples were evaluated. Baseline subtype distribution: HER2-enriched (HER2-E) 63%, Luminal A 11%, Basal-like 8.9%, Normal-like 8.9% and Luminal B 7.8%. Although HER2-E predominated in HR-neg tumors (74%), 53% of HR+ tumors were HER2-E. pCR rates varied according to intrinsic subtype (P&lt;0.001). HER2-E tumors were associated with higher pCR rates compared to non-HER2-E (68.4% vs 33.3%, P&lt;0.001) regardless HR-status. Five of the 8 PAM50 signatures (HER2E, ROR-S, ROR-P, Basal-like and Proliferation score) were associated with pCR, whereas Luminal A was associated with no-pCR (P&lt;0.001). With a median follow-up of 6.6 years, HER2-E subtype was associated with a better DFS compared to non-HER2-E (5-year DFS 92.4% vs 75.9%; HR= 0.27; 95% CI 0.08-0.91; P=0.034). Finally, 28 of the 66 (42.4%) surgical specimens with residual disease were studied. Residual subtype distribution was: Normal-like (50.0%), Luminal A (32.1%), HER2-E (14.3%) and Luminal B (3.5%).

Conclusions: In this consecutive series of HER2-positive BCtreated homogeneously with neoadjuvant trastuzumab-based PC, all of the main intrinsic molecular subtypes were identified with a predominance of HER2-E. HER2-E was significantly associated with pCR and survival outcome. Distribution of the intrinsic subtypes in residual disease differed from untreated tumors.

Citation Format: Pernas S, Petit A, Climent F, Pare L, Perez-Martin J, Ventura L, Galvan P, Falo C, Morilla I, Fernandez-Ortega A, Stradella A, Pascual T, Gil-Gil M, Prat A. PAM50 intrinsic subtyping as a predictor of pathological complete response to neoadjuvant trastuzumab-based chemotherapy in early HER2-positive breast cancer [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 P2-09-11.