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To assess the long-term (20-year) endocrine therapy benefit in premenopausal patients with breast cancer.Secondary analysis of the Stockholm trial (STO-5, 1990-1997) randomly assigning 924 premenopausal patients to 2 years of goserelin (3.6 mg subcutaneously once every 28 days), tamoxifen (40 mg orally once daily), combined goserelin and tamoxifen, or no adjuvant endocrine therapy (control) is performed. Random assignment was stratified by lymph node status; lymph node-positive patients (n = 459) were allocated to standard chemotherapy (cyclophosphamide, methotrexate, and fluorouracil). Primary tumor immunohistochemistry (n = 731) and gene expression profiling (n = 586) were conducted in 2020. The 70-gene signature identified genomic low-risk and high-risk patients. Kaplan-Meier analysis, multivariable Cox proportional hazard regression, and multivariable time-varying flexible parametric modeling assessed the long-term distant recurrence-free interval (DRFI). Swedish high-quality registries allowed a complete follow-up of 20 years.In estrogen receptor-positive patients (n = 584, median age 47 years), goserelin, tamoxifen, and the combination significantly improved long-term distant recurrence-free interval compared with control (multivariable hazard ratio [HR], 0.49; 95% CI, 0.32 to 0.75, HR, 0.57; 95% CI, 0.38 to 0.87, and HR, 0.63; 95% CI, 0.42 to 0.94, respectively). Significant goserelin-tamoxifen interaction was observed (This study shows 20-year benefit from 2 years of adjuvant endocrine therapy in estrogen receptor-positive premenopausal patients and suggests differential treatment benefit on the basis of tumor genomic characteristics. Combined goserelin and tamoxifen therapy showed no benefit over single treatment. Long-term follow-up to assess treatment benefit is critical.

BRAFV600E mutation confers a poor prognosis in metastatic colorectal cancer (CRC) despite combinatorial targeted therapies based on the latest understanding of signaling circuitry. To identify parallel resistance mechanisms induced by BRAF–MEK–EGFR co-targeting, we used a high-throughput kinase activity mapping platform. Here we show that SRC kinases are systematically activated in BRAFV600E CRC following targeted inhibition of BRAF ± EGFR and that coordinated targeting of SRC with BRAF ± EGFR increases treatment efficacy in vitro and in vivo. SRC drives resistance to BRAF ± EGFR targeted therapy independently of ERK signaling by inducing transcriptional reprogramming through β-catenin (CTNNB1). The EGFR-independent compensatory activation of SRC kinases is mediated by an autocrine prostaglandin E2 loop that can be blocked with cyclooxygenase-2 (COX2) inhibitors. Co-targeting of COX2 with BRAF + EGFR promotes durable suppression of tumor growth in patient-derived tumor xenograft models. COX2 inhibition represents a drug-repurposing strategy to overcome therapeutic resistance in BRAFV600E CRC.

Introduction: Prognostic gene expression signatures can be used in combination with classical clinicopathological factors to guide adjuvant chemotherapy decisions in ER-positive, HER2-negative breast cancer. However, long-term outcome data after introduction of genomic testing in the treatment decision-making process are limited. Methods: In the prospective RASTER study, the tumours of 427 patients with cTanyN0M0 breast cancer were tested to assess the 70-gene signature (MammaPrint). The results were provided to their treating physician to be incorporated in the decision-making on adjuvant systemic therapy. Here, we report the long-term outcome of the 310 patients with ER-positive, HER2-negative tumours by clinical and genomic risk categories at a median follow-up of 10.3 years. Results: Among the clinically high-risk patients, 45 (49%) were classified as genomically low risk. In this subgroup, at 10 years, distant recurrence free interval (DRFI) was similar between patients treated with (95.7% [95% CI 87.7–100]) and without (95.5% [95% CI 87.1–100]) chemotherapy. Within the group of clinically low-risk patients, 56 (26%) were classified as genomically high risk. Within the clinically low-risk group, beyond 5 years, a difference emerged between the genomically high- and low-risk subgroup resulting in a 10-year DRFI of 84.3% (95% CI 74.8–95.0) and 93.4% (95% CI 89.5–97.5), respectively. Interestingly, genomic ultralow-risk patients have a 10-year DRFI of 96.7% (95% CI 90.5–100), largely (79%) without systemic therapy. Conclusions: These data confirm that clinically high-risk, genomically low-risk tumours have an excellent outcome in the real-world setting of shared decision-making. Together with the updated results of the MINDACT trial, these data support the use of the MammaPrint, in ER-positive, HER2-negative, node-negative, clinically high-risk breast cancer patients. Registry: ISRCTN71917916

Supplemental Methods. Supplemental Table 1: ââ,¬â€¹Genomic Data Characterization by Center. Supplemental Table 2: ââ,¬â€¹Gene Panels Submitted by Each Center. Figure S1: Number of putative germline SNPs per sample, before and after uniform germline filtering. Figure S2ââ,¬â€¹. Distribution of total somatic mutation burden per sample stratified by sequencing panel. Figure S3: ââ,¬â€¹Log-scale comparison of mutation frequencies at hotspot sites between GENIE (data aggregated from all sequencing panels) and cancerhotspots.org (CHS) using a binomial test. Figure S4:ââ,¬â€¹ Comparison of mutation frequencies at hotspot sites in each GENIE sequencing panel with cancerhotspots.org (CHS) using a binomial test.

Table S4

AACR GENIE Data Guide

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Background: The single-nucleotide polymorphism (SNP) 5p12-rs10941679 has been found to be associated with risk of breast cancer, particularly estrogen receptor (ER)-positive disease. We aimed to further explore this association overall, and by tumor histopathology, in the Breast Cancer Association Consortium.Methods: Data were combined from 37 studies, including 40,972 invasive cases, 1,398 cases of ductal carcinoma in situ (DCIS), and 46,334 controls, all of white European ancestry, as well as 3,007 invasive cases and 2,337 controls of Asian ancestry. Associations overall and by tumor invasiveness and histopathology were assessed using logistic regression.Results: For white Europeans, the per-allele OR associated with 5p12-rs10941679 was 1.11 (95% CI = 1.08–1.14, P = 7 × 10−18) for invasive breast cancer and 1.10 (95% CI = 1.01–1.21, P = 0.03) for DCIS. For Asian women, the estimated OR for invasive disease was similar (OR = 1.07, 95%CI = 0.99–1.15, P = 0.09). Further analyses suggested that the association in white Europeans was largely limited to progesterone receptor (PR)-positive disease (per-allele OR = 1.16, 95% CI = 1.12–1.20, P = 1 × 10−18 vs. OR = 1.03, 95% CI = 0.99–1.07, P = 0.2 for PR-negative disease; Pheterogeneity = 2 × 10−7); heterogeneity by ER status was not observed (P = 0.2) once PR status was accounted for. The association was also stronger for lower grade tumors [per-allele OR (95% CI) = 1.20 (1.14–1.25), 1.13 (1.09–1.16), and 1.04 (0.99–1.08) for grade 1, 2, and 3/4, respectively; Ptrend = 5 × 10−7].Conclusion: 5p12 is a breast cancer susceptibility locus for PR-positive, lower grade breast cancer.Impact: Multicenter fine-mapping studies of this region are needed as a first step to identifying the causal variant or variants. Cancer Epidemiol Biomarkers Prev; 20(10); 2222–31. ©2011 AACR.

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Kinase inhibitors are used widely to treat various cancers, but adaptive reprogramming of kinase cascades and activation of feedback loop mechanisms often contribute to therapeutic resistance. Determining comprehensive, accurate maps of kinase circuits may therefore help elucidate mechanisms of response and resistance to kinase inhibitor therapies. In this study, we identified and validated phosphorylatable target sites across human cell and tissue types to generate PhosphoAtlas, a map of 1,733 functionally interconnected proteins comprising the human phospho-reactome. A systematic curation approach was used to distill protein phosphorylation data cross-referenced from 38 public resources. We demonstrated how a catalog of 2,617 stringently verified heptameric peptide regions at the catalytic interface of kinases and substrates could expose mutations that recurrently perturb specific phospho-hubs. In silico mapping of 2,896 nonsynonymous tumor variants identified from thousands of tumor tissues also revealed that normal and aberrant catalytic interactions co-occur frequently, showing how tumors systematically hijack, as well as spare, particular subnetworks. Overall, our work provides an important new resource for interrogating the human tumor kinome to strategically identify therapeutically actionable kinase networks that drive tumorigenesis. Cancer Res; 76(7); 1733–45. ©2016 AACR.

Legends for Supplementary Figures S1-S17.

Phospho-reactome curation workflow (S1); Proteins catalogued in PhosphoAtlas correspond to a unique subset of Protein-Protein Interactions, defined by their active, proven function in phospho-catalytic events (S2); Comparative connectivity between kinases, substrates and HPS's (S3); Most highly connected kinases and substrates (S4); Comparison between the number of enzyme - substrate pairs and the number of kinase - HPS - substrate connections across kinase subfamilies (S5); Disease ontology profile of AKT phospho-circuits (S6); Connectivity of AKT proteins to their upstream and downstream phospho-protein circuits (S7); Catalytic circuitry of AKT1 kinase: an expandable network of enzymatic interaction derived from mutation-prone phospho-target sites (S8); Identification of substrate proteins that are most affected by cancer-mutated peptides, and substrates that are not subject to alterations of their phospho-target sites (S9); Distribution and classification of SNP-altering target sites (S10); Heptameric target variants affecting phosphorylation sites mapped to COSMIC-curated tissue pathologies (S11); Identification of kinases impacted by cancer-mutations that alter their phosphorylatable target sites (S12); Map of the tumor kinome (S13, S14); Examples of kinase and substrate sub-networks, and the differential impact of tumor mutations on their phospho-signaling circuits (S15, S16, S17).

Description of additional methods and procedures used in the study. Also includes Supplementary References.

Background: There is no clinical equipoise on the best upfront management of patients with early-stage hormone receptor-positive (HR+)/HER2-negative (HER2-) breast cancer (BC) that is high-risk by clinicopathologic criteria, and low-risk based on molecular profiling. These patients are unlikely to respond to chemotherapy. However, these patients still have risk, often risk of late recurrence, despite standard adjuvant endocrine therapy. Novel endocrine-based strategies that are more effective and tolerable than current standard therapies are needed for this population. Next-generation orally-bioavailable selective estrogen receptor degraders (oSERDs) with improved pharmacokinetic (PK) properties are promising potential therapies for HR+ BC. The oSERD amcenestrant has demonstrated a favorable safety profile and encouraging efficacy in a phase I/II dose escalation and expansion trial for heavily pre-treated patients with HR+ metastatic BC and is an attractive agent for assessment in the neoadjuvant BC setting. The neoadjuvant setting offers a unique opportunity to study novel agents and to assess early biological endpoints. However, one of the challenges in studying endocrine-based strategies in the neoadjuvant setting is the lack of a robust surrogate endpoint to reliably predict response and benefit. The I-SPY2 Endocrine Optimization Protocol (EOP) is a pilot sub-study within the main I-SPY2 TRIAL that will test amcenestrant alone or in combination with abemaciclib or letrozole. EOP will test the feasibility of using the I-SPY2 platform to test novel endocrine-based strategies in the neoadjuvant setting in patients with clinical high-risk, molecular low-risk, HR+/HER2- tumors, and will generate a rich database of imaging, molecular, and pathologic correlative endpoints that may potentially inform the improved assessment of response to neoadjuvant endocrine therapy. Trial Design/Eligibility/Accrual: The I-SPY2 EOP is a prospective, randomized, open-label trial specifically for patients with HR+/HER2-negative MammaPrint (MP) low-risk tumors that are at least 2.5 cm in size. Eligible patients are identified during the screening process for the parent I-SPY2 trial. The planned total accrual for the EOP is 120 patients. Patients are randomized 1:1:1 to one of 3 oral treatment arms: 1) amcenestrant 200 mg daily; 2) amcenestrant 200 mg daily + abemaciclib 150 mg bid; 3) amcenestrant 200 mg daily + letrozole 2.5 mg daily. Patients are treated for 6 months prior to surgery. Premenopausal women must receive concomitant monthly ovarian suppression. Serial breast MRIs, breast biopsies, blood, and patient reported outcomes (PROs) are being collected, and patients will be followed for 10 years for recurrence and survival. Serial dedicated breast PET (dbPET) scans and PKs will be assessed in a subset of patients. Objectives/Statistics: The primary objective of the EOP is to investigate the feasibility of enrolling and treating molecularly-selected patients with early stage HR+/HER2- MP low-risk BC in a randomized neoadjuvant trial using an oral-SERD backbone. Treatment will be determined to be feasible if ≥75% of enrolled patients complete ≥75% of assigned study therapy. Secondary objectives include the safety, tolerability, PROs, and PKs related to amcenestrant +/- abemacilcib and letrozole, as well as the assessment of imaging, pathologic, and molecular correlative endpoints as potential biomarkers of response to neoadjuvant endocrine therapy. Status: This study opened in May 2021. Accrual is ongoing. Citation Format: A. Jo Chien, Kevin M Kalinsky, Julissa Molina-Vega, Rita Mukhtar, Karthik Giridhar, Olufunmilayo I Olopade, Amrita Basu, Smita M Asare, Paul Henderson, Gillian Hirst, Ruixiao Lu, Ella Jones, Nola Hylton, Lamorna Brown-Swigart, Laura J van 't Veer, Douglas Yee, Ingrid Mayer, Laura J Esserman. I-SPY2 endocrine optimization protocol (EOP): A pilot neoadjuvant endocrine therapy study with amcenestrant as monotherapy or in combination with abemacicilib or letrozole in molecularly selected HR+/HER2- clinical stage 2/3 breast cancer [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 OT1-10-02.

PURPOSECyclin-dependent kinase 4/6 (CDK4/6) inhibitors have emerged as effective treatments for patients with hormone receptor–positive (HR+)/human epidermal growth factor receptor 2–negative (HER2–) advanced/metastatic breast cancer (mBC). Dedicated research efforts have been undertaken to find predictive biomarkers of response or resistance to these therapies although no molecular biomarkers for mBC have reached the clinic so far. This review aims to summarize and evaluate the performance of biomarkers in predicting progression-free survival in phase II and III clinical trials of CDK4/6 inhibitors in HR+/HER2– mBC.METHODSFor this narrative review, a structured literature search of PubMed, Embase, and the Cochrane library (CENTRAL) was performed. Phase II or III clinical trials of a CDK4/6 inhibitor in patients with HR+/HER2– mBC reporting on at least one molecular biomarker analysis of progression-free survival were included. Publications and selected conference abstracts were included up until November 2021.RESULTSTwenty-two articles reporting biomarker results of 12 clinical trials were included. Retinoblastoma protein status and cyclin E1 mRNA expression were promising baseline biomarkers, whereas PIK3CA circulating tumor DNA ratio on treatment relative to baseline, change in plasma thymidine kinase activity, and circulating tumor cell count were potential dynamic biomarkers of response. A number of biomarkers were unsuccessful, despite a strong mechanistic rationale, and others are still being explored.CONCLUSIONOur review of clinical trials showed that there are a number of promising biomarkers at baseline and several dynamic biomarkers that might predict response to CDK4/6 inhibitors. Validation of these findings and assessment of clinical utility are crucial to make the final translation to clinical practice. Better understanding of disease heterogeneity and further elucidation of resistance mechanisms could inform future studies of rationally selected biomarkers.

PURPOSE Patients with 70-gene signature ultralow-risk breast cancers have shown excellent survival in historic cohorts, including randomized trials. The ultralow-risk subgroup was characterized to help avoid overtreatment. We evaluated outcomes of ultralow-risk patients in the largest cohort to date. METHODS Of the 6,693 patients enrolled in the EORTC-10041/BIG-3-04 randomized phase III MINDACT trial, profiling revealed an ultralow-risk 70-gene signature in 1,000 patients (15%). Distant metastasis-free interval (DMFI) and breast cancer–specific survival (BCSS) were assessed in patients stratified by 70-gene signature result (high, low, and ultralow) by Kaplan-Meier analysis and hazard ratios with 95% CI from Cox regression. RESULTS Median follow-up was 8.7 years. Of the ultralow-risk patients (n = 1,000), 67% were > 50 years, 81% had tumors ≤ 2 cm, 80% were lymph node–negative, 96% had grade 1 or 2 tumors, and 99% were estrogen receptor (ER)-positive. Systemic therapy was received by 84% of patients (69% endocrine therapy, 14% endocrine therapy plus chemotherapy, 1% other) and 16% received no adjuvant systemic treatment. The 8-year DMFI for ultralow-risk patients was 97.0% (95% CI, 95.8 to 98.1), which was 2.5% higher than for patients with low-risk tumors (n = 3,295, 94.5% [95% CI, 93.6 to 95.3]). The hazard ratio for DMFI was 0.65 (95% CI, 0.45 to 0.94) for ultralow versus low risk, after adjusting for clinical-pathologic and treatment characteristics. The 8-year BCSS for ultralow-risk patients was 99.6% (95% CI, 99.1 to 100). CONCLUSION Patients with an ultralow-risk 70-gene signature have the best prognosis, distinctive from low risk, with 8-year BCSS above 99%, and very few patients developed distant metastases with an 8-year DMFI rate of 97%. These patients could be candidates for further de-escalation of treatment, to avoid overtreatment and the risk of side effects.

Background: Previous studies have independently validated the prognostic relevance of residual cancer burden (RCB) after neoadjuvant chemotherapy. We used results from several independent cohorts in a pooled patient-level analysis to evaluate the relationship of RCB with long-term prognosis across different phenotypic subtypes of breast cancer, to assess generalisability in a broad range of practice settings. Methods: In this pooled analysis, 12 institutes and trials in Europe and the USA were identified by personal communications with site investigators. We obtained participant-level RCB results, and data on clinical and pathological stage, tumour subtype and grade, and treatment and follow-up in November, 2019, from patients (aged ≥18 years) with primary stage I–III breast cancer treated with neoadjuvant chemotherapy followed by surgery. We assessed the association between the continuous RCB score and the primary study outcome, event-free survival, using mixed-effects Cox models with the incorporation of random RCB and cohort effects to account for between-study heterogeneity, and stratification to account for differences in baseline hazard across cancer subtypes defined by hormone receptor status and HER2 status. The association was further evaluated within each breast cancer subtype in multivariable analyses incorporating random RCB and cohort effects and adjustments for age and pretreatment clinical T category, nodal status, and tumour grade. Kaplan-Meier estimates of event-free survival at 3, 5, and 10 years were computed for each RCB class within each subtype. Findings: We analysed participant-level data from 5161 patients treated with neoadjuvant chemotherapy between Sept 12, 1994, and Feb 11, 2019. Median age was 49 years (IQR 20–80). 1164 event-free survival events occurred during follow-up (median follow-up 56 months [IQR 0–186]). RCB score was prognostic within each breast cancer subtype, with higher RCB score significantly associated with worse event-free survival. The univariable hazard ratio (HR) associated with one unit increase in RCB ranged from 1·55 (95% CI 1·41–1·71) for hormone receptor-positive, HER2-negative patients to 2·16 (1·79–2·61) for the hormone receptor-negative, HER2-positive group (with or without HER2-targeted therapy; p

Liquid biopsy biomarkers, such as circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), are noninvasive diagnostics that could complement predictive and prognostic tools currently used in the clinic. Recent trials of immunotherapy have shown promise in improving outcomes in a subset of breast cancer patients. Biomarkers could improve the efficacy of immune checkpoint inhibitors by identifying patients whose cancers are more likely to respond to immunotherapy. In this review, we discuss the current applications of liquid biopsy and emerging technologies for evaluation of immunotherapy response and outcomes in breast cancer. We also provide an overview of the status of immunotherapy in breast cancer.

HSP90 inhibitors destabilize oncoproteins associated with cell cycle, angiogenesis, RAS-MAPK activity, histone modification, kinases and growth factors. We evaluated the HSP90-inhibitor ganetespib in combination with standard chemotherapy in patients with high-risk early-stage breast cancer. I-SPY2 is a multicenter, phase II adaptively randomized neoadjuvant (NAC) clinical trial enrolling patients with stage II-III breast cancer with tumors 2.5 cm or larger on the basis of hormone receptors (HR), HER2 and Mammaprint status. Multiple novel investigational agents plus standard chemotherapy are evaluated in parallel for the primary endpoint of pathologic complete response (pCR). Patients with HER2-negative breast cancer were eligible for randomization to ganetespib from October 2014 to October 2015. Of 233 women included in the final analysis, 140 were randomized to the standard NAC control; 93 were randomized to receive 150 mg/m2 ganetespib every 3 weeks with weekly paclitaxel over 12 weeks, followed by AC. Arms were balanced for hormone receptor status (51–52% HR-positive). Ganetespib did not graduate in any of the biomarker signatures studied before reaching maximum enrollment. Final estimated pCR rates were 26% vs. 18% HER2-negative, 38% vs. 22% HR-negative/HER2-negative, and 15% vs. 14% HR-positive/HER2-negative for ganetespib vs control, respectively. The predicted probability of success in phase 3 testing was 47% HER2-negative, 72% HR-negative/HER2-negative, and 19% HR-positive/HER2-negative. Ganetespib added to standard therapy is unlikely to yield substantially higher pCR rates in HER2-negative breast cancer compared to standard NAC, and neither HSP90 pathway nor replicative stress expression markers predicted response. HSP90 inhibitors remain of limited clinical interest in breast cancer, potentially in other clinical settings such as HER2-positive disease or in combination with anti-PD1 neoadjuvant chemotherapy in triple negative breast cancer.Trial registration: www.clinicaltrials.gov/ct2/show/NCT01042379

Using pre-treatment gene expression, protein/phosphoprotein and clinical data from the I-SPY2 neoadjuvant platform trial (NCT01042379), we create alternative breast cancer subtypes incorporating tumor biology beyond clinical hormone-receptor (HR) and Human Epidermal Growth Factor Receptor-2 (HER2) status to better predict drug responses. We assess predictive performance of mechanism-of-action biomarkers from ~990 patients treated with 10 regimens targeting diverse biology. We explore >11 subtyping schemas and identify treatment-subtype pairs maximizing pathologic complete response (pCR) rate over the population. The best performing schemas incorporate Immune, DNA-repair and HER2/Luminal phenotypes. Subsequent treatment allocation increases overall pCR rate to 63% from 51% using HR/HER2-based treatment selection. pCR gains from reclassification and improved patient selection are highest in HR+ subsets (>15%). As new treatments are introduced, the subtyping schema determines the minimum response needed to show efficacy. This data platform provides an unprecedented resource and supports the usage of response-based subtypes to guide future treatment prioritization.

Background: I-SPY 2 is a multicenter, phase 2 trial using response-adaptive randomization within molecular subtypes defined by receptor status and MammaPrint (MP) risk to evaluate novel agents as neoadjuvant therapy for women with high-risk breast cancer. Tucatinib is a potent HER2 (ErbB2) tyrosine kinase inhibitor, selective for HER2 vs. epidermal growth factor receptor (EGFR) and is active vs. brain metastases. Safety and efficacy of tucatinib combined with paclitaxel, pertuzumab, and trastuzumab are unknown and were tested in a planned 10 patient (pt) safety run-in of the I-SPY 2 trial. Methods: Women with tumors ≥ 2.5cm were eligible for screening. Only pts with tumors that were HER2+ by FISH were eligible for this treatment. Treatment included tucatinib (max dose 300 mg) BID for 12 weeks with weekly paclitaxel 80 mg/m2 and trastuzumab (2 mg/kg weekly following loading), and pertuzumab (420 mg every 3 weeks following loading), followed by doxorubicin/cyclophosphamide (AC) every 2 weeks x 4. The control arm was weekly paclitaxel and trastuzumab with pertuzumab for 12 weeks followed by AC every 2 weeks x 4. All pts undergo serial MR imaging and response at 3 & 12 weeks is combined with real time pCR data to estimate, and continuously update, the predicted pCR rate for each trial arm. The goal of the trial is to identify/graduate regimens with ≥85.% Bayesian predictive probability of success (i.e. demonstrating superiority to control) in a future 300-patient phase 3 neoadjuvant trial with a pCR endpoint. This run-in arm was conducted to determine safety of combining tucatinib with paclitaxel/trastuzumab/pertuzumab, monitoring special adverse events of interest including LFT elevations and gastrointestinal toxicities.Methods: The I-SPY 2 methods have been previously published. Results: 20 pts were evaluable in tucatinib treatment arm. The control arm included 329 historical controls enrolled since April 2010. The initial tucatinib dose was 300 mg BID. After enrollment of the first 8 pts, there were 3 pts with grade 3 LFT elevations, 2 pts with grade 2/3 diarrhea, 1 pt with grade 2 neutropenia, and 1 pt with grade 3 nausea. After this safety review, the tucatinib dose was lowered to 250 mg BID. Among 5 additional pts enrolled, 3 developed grade 2/3 LFT abnormalities. The protocol was then modified to tucatinib 150 mg BID days 1-28 and then 250 mg BID days 29-84; 7 pts were treated. Safety data were reviewed after 20 pts were enrolled; the arm was then suspended due to similar LFT elevations regardless of tucatinib dose reduction or schedule. 7 of 20 pts (35%) had reversible Grade 3 or higher ALT/AST elevation (Table). No pt met criteria for Hy’s Law. In terms of efficacy, 12 of 14 evaluable pts had > 80% reduction of tumor volume by 12 weeks, measured by MRI assessment of functional tumor volume (FTV). Conclusion: The goal of the run-in arm was to determine the safety of adding tucatinib to the combination of paclitaxel/trastuzumab/pertuzumab. The addition of tucatinib resulted in unacceptable but reversible LFT elevations despite tucatinib dose reduction. Tucatinib containing therapy resulted in >80% decline in tumor volume at 12 weeks in 86% of pts. Tucatinib showed a high level of activity when combined with paclitaxel/trastuzumab/pertuzumab, but the combination is not feasible. Table: Number of pts with grade 2, 3, and 4 LFT elevations by treatment schedule (highest grade per patient per event, ALT or Treatment scheduleGrade 2 LFT elevationGrade 3 LFT elevationGrade 4 LFT elevationTucatinib 300 mg BID030Tucatinib 250 mg BID210Tucatinib 150 mg BID days 1-28 followed by 250 mg BID days 29 to 84112 Citation Format: David A Potter, Erin Roesch, Christina Yau, Ruixiao Lu, Denise Wolf, Susan Samson, Debra Stafford, Kathy S Albain, Claudine Isaacs, Meghana Trivedi, Douglas Yee, Judy Boughey, Alexandra Thomas, A. Jo Chien, Nola Hylton, Wen Li, Angela DeMichele, Jane Perlmutter, W. Fraser Symmans, Dawn L Hershman, Michelle Melisko, Laura J van 't Veer, Amy Wilson, Smita M Asare, Donald A Berry, Richard Schwab, Hope S Rugo, Laura J Esserman. Evaluation of Tucatinib + (Paclitaxel + Pertuzumab + Trastuzumab) followed by AC in high-risk HER2 positive (HER2+) stage II/III breast cancer: Results from the I-SPY 2 TRIAL [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 PD8-07.

Background With 8.7 years follow-up, the prospective phase III randomized MINDACT trial (EORTC 10041/BIG3-04) continues to meet its primary objective, i.e. 95.1% (95%CI 93.1-96.6), 5-year distant metastasis-free survival (DMFS) in clinical high (C-High)/genomic low (G-Low) risk patients who did not receive adjuvant chemotherapy (ACT) (Cardoso et al., ASCO 2020). In addition, about half of the MINDACT patients had a low clinical risk (C-Low) defined by pre-specified clinical-pathological characteristics. Here, we evaluated the outcome of this C-Low population stratified by the 70-gene signature (MammaPrint®) (G-Low or G-High) for outcome considering age, and present data on the total G-low population (C-Low and C-High combined). Methods Of 6693 patients enrolled in the MINDACT trial between 2007 and 2011, 3337 were C-Low, characterized as mainly T1, grade 1 or 2, and node negative. We evaluated the pre-specified DMFS, distant metastasis free interval (DMFI), and overall survival (OS) rates at 5 and 8 years in the C-Low population: i) in patients with genomic low risk (C-Low/G-Low, n=2744) who were recommended to receive endocrine therapy only (for 99% HR+), and ii) in C-Low/G-High who received ACT or not following randomization (ITT, n=690, 81% HR+). Exploratory analyses by age, ≤50 and >50, were conducted for ACT vs no ACT received in C-Low/G-High. In parallel we estimated survival rates for all G-low patients if all would have followed the genomic low risk assignment and received no ACT (C-Low/G-Low, and C-High/G-Low randomized to no ACT double weighted, n=4130). We used Kaplan-Meier estimates for time to event endpoints and hazard ratios with 95%CI from Cox-regression models adjusted for stratification factors used for the randomization. Results C-low/G-low patients who were recommended endocrine therapy only (compliance > 79%, based on local guidelines) have excellent 5 and 8 year survival rates for all endpoints (Table 1). The estimated survival rates for all G-Low patients, if all would have followed the genomic low risk assignment and received no ACT, is excellent as well (Table 1), albeit this population includes both C-Low and C-High patients. The survival estimates for C-Low/G-High patients are for all endpoints a few percentage points lower than for the C-Low/G-Low group (Table 1). At 8 years of follow-up, in the relatively small subset of 690 patients with C-Low/G-High tumors assigned to ACT or not by randomization (ITT), a 1.5% (SE ±2.3%) higher DMFS is seen in the ACT group, and a 2.9% (SE ±2.0%) higher DMFI. This suggested benefit is mostly seen in patients under 50 years of age (absolute Δ in DMFS for ACT vs no ACT at 8 years: 5.4% for age ≤50 vs -0.3% for age >50). Conclusion Patients with a 70-gene G-Low risk tumor have an excellent 8 year outcome in the context of C-Low characteristics when recommended for endocrine therapy only, very close to the outcome in the larger group of all G-Low patients regardless of clinical risk. Stratification of C-Low patients in to G-Low and G-high provides meaningful information. The benefit of ACT in C-Low patients with a 70-gene G-High risk tumor needs further confirmation, especially relevant in younger women. Table 1All Patients PopulationPatientsObserved events% at 5 years (95% CI)% at 8 years (95% CI)DMFSC-Low / G-Low274417097.3 (96.6-97.9)94.7 (93.8-95.6)C-Low / G-High5936194.2 (92.0-95.9)91.1 (88.4-93.3)DMFIC-Low / G-Low274410398.5 (97.9-98.9)96.7 (95.9-97.3)C-Low / G-High5934695.8 (93.8-97.2)93.5 (91.0-95.3)OSC-Low / G-Low274412298.2 (97.6-98.7)96.5 (95.7-97.2)C-Low / G-High5934496.8 (94.9-98.0)93.1 (90.5-95.0)Patients G-low (C-Low & C-High)PatientsEstimated events% at 5 years% at 8 yearsDMFSAll G-Low - no ACT413033996.492.8DMFIAll G-Low - no ACT413024497.494.6OSAll G-Low - no ACT413022397.995.7 Citation Format: Laura J van 't Veer, Fatima Cardoso, Coralie Poncet, Josephine Lopes Cardozo, Suzette Delaloge, Jean-Yves Pierga, Peter Vuylsteke, Etienne Brain, Giuseppe Viale, Sherko Kümmel, Isabel T Rubio, Gabriele Zoppoli, Alistair Thompson, Erika Matos, Khalil Zaman, Susan Knox, Florentine Hilbers, Aleksandra Peric, Bart Meulemans, Martine Picccart, Emiel J Th Rutgers. How low is low risk: MINDACT updated outcome and treatment benefit in patients considered clinical low risk and stratified by genomic signature, age and nodal status [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-01.

Background Biology has become the main driver of breast cancer (BC) therapy. Biological subtypes have been recommended as a guide for treatment selection. Molecularly identified subtypes can be determined by gene expression profiling. Alternatively, pathology can be used to define surrogates of these subtypes. These methodologies are not always concordant, which can lead to different systemic therapies. The purpose of this preplanned translational research is to investigate the concordance between molecular based BluePrint and MammaPrint breast cancer subtypes and pathological surrogates (based on ER, PgR, HER2 & Ki67) and to characterize the discordant cases. Methods MINDACT is an international, prospective, randomized, phase III trial investigating the clinical utility of MammaPrint in selecting patients with early BC for adjuvant chemotherapy (CT), which enrolled 6,694 patients. Molecular subtyping data were obtained by MammaPrint and BluePrint (Agendia, Amsterdam, the Netherlands) on frozen samples (n=6,694) classifying patients in the following subtypes: Luminal A (Luminal-type/MammaPrint Low Risk); Luminal B (Luminal-type/MammaPrint High Risk); HER2-type; and Basal-type. ER, PgR, HER2 and Ki67 protein status were centrally assessed on FFPE blocks by IHC and/or FISH in the European Institute of Oncology, Milan, Italy (n=5,740; 86%). Patients were also classified according to the St. 2013 Gallen recommendations [Goldhirsch et al. 2013], which recognizes an additional category (Luminal B-like HER2+). Results Ki67 is often used as biomarker to distinguish Luminal A from Luminal B subgroups. The concordance between MammaPrint and centrally assessed Ki67 in Luminal-type patients is 60%, with a κ score of 0.26 (95% CI 0.24–0.28) indicating that Ki67 and MammaPrint cannot reliably substitute for each other. When using a cut-point of 20% instead of 14% the concordance increased to 78%, with a κ score of 0.44 (95% CI 0.41–0.47). There is a relatively large group of clinical HER2+ cases that are BluePrint Luminal-type (208 out of 541; 38%) indicating that tumor expression of the Luminal profile is dominant compared with expression of the HER2 profile. These patients have high IHC ER results and all except for 1 fall into the group that St Gallen separately defines as Luminal B-like HER2-positive. These patients may have lower response to trastuzumab [von Minckwitz et al. JCO 2012]. 98 out of 622 BluePrint Basal-type patients are clinical Luminal HER2-. 2/3 of these patients have low centrally assessed IHC PR expression and 1/3 have low centrally assessed ER expression (≥1% and Conclusions Marked differences are observed between BluePrint and MammaPrint (microarray based) breast cancer subtypes and centrally re-assessed pathological surrogates (based on ER, PR, HER2 & Ki67). The greatest discordance is seen in the sub-stratification of Luminal patients, and in the HR+/HER2+ patients. The observed subtype discrepancies may have an important impact on treatment decision making. Citation Format: Giuseppe Viale, Leen Slaets, Femke A de Snoo, Jan Bogaerts, Laura J van 't Veer, Emiel J Rutgers, Martine J Piccart-Gebhart, Jeroen van den Akker, Lisette Stork-Sloots, Leila Russo, Patrizia Dell'Orto, Fatima Cardoso, On Behalf of the TRANSBIG Consortium & the MINDACT Investigators. Pathological assessment of discordant cases for molecular (BluePrint and MammaPrint) vs clinical subtypes for breast cancer, among 6,694 patients from the EORTC 10041/BIG 3-04 (MINDACT) trial [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P4-11-08.

Background: A major area of innovation in breast cancer (BC) is improving risk models for screening efforts. The University of California Athena Breast Health Network uses several risk models, including the Gail model [PMID: 10491430]. The Breast Cancer Surveillance Consortium (BCSC) model [PMID: 18316752] which integrated information on breast density was developed and validated by UCSF investigators and reports Asian-specific risk. The Peking Union Medical College (PUMC) model [PMID: 22662004] is developed from a case-control study in China and reports BC risk in Chinese women. Risk factors and their respective weights included in these models are different. Methods: From December 2012 to April 2014, 2,305 women without previous history of BC and consented to research were enrolled in the UCSF Athena screening cohort. Questions asked included risk factors used in Gail, BCSC and PUMC model, such as age, age of menarche (AOM), age at first live birth, body mass index (BMI), breast biopsy, breast density, hormone replacement therapy (HRT), oral contraceptives (OCP). Women were considered high risk when: Gail > 1.67% 5-year risk, BCSC > 1.67% 5-year risk, PUMC score > 30 (equals >0.20% 1-year risk) respectively. The distribution of the risk factors and the high risk population percentage were compared between Chinese women versus non-Chinese Asian and Caucasian women. Results: 402 Asian women comprise 17.4% of all 2,305 Athena screening cases with 234 Chinese, and 168 non-Chinese Asian (NCA). Differences in risk factor distribution were observed for the following: positive family history was observed 23% for Caucasian, 15% for Chinese and 13% for NCA (p=0.001), and previous breast biopsy was 27%, 17% and 22% respectively (p=0.002). Ever use of HRT was 36% in Caucasian, 17% in Chinese and 11% in NCA (p Table 1 Percentage of high risk population by ethnicity for different risk modelsRisk modelsChinese (n=234)non-Chinese Asian (n=168)Caucasian (n=1,492)P ValueRisklowhighlowhighlowhighGail137 (58.6%)97 (41.4%)107 (63.7%)61 (36.3%)884 (59.2%)608 (40.8%)0.509BCSC211 (90.2%)23 (9.8%)152 (90.5%)16 (9.5%)864 (58.0%)626 (42.0%)0.000PUMC167 (71.7%)66 (28.3%)108 (64.7%)59 (35.3%)781 (52.6%)704 (47.4%)0.000 Conclusion: Chinese and NCA women have a lower proportion of high risk by the BCSC and PUMC model compared to the Caucasian women, whereas by Gail model these proportions appear to be similar. Citation Format: Bo Pan, Jeffrey Tice, Qiang Sun, Celia Kaplan, Zhou Yidong, Yali Xu, Songjie Shen, Changjun Wang, Alexandra Solomon, Lauren Ryan, Paige Kendall, Timothy Henderson, Laura Esserman, Beth Crawford, Athena Breast Health Network, Laura van 't Veer. The comparison of the distribution of breast cancer risk factor between Chinese women, non-Chinese Asian and Caucasian women in the screening cohort of Athena Breast Health Network [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-09-10.

Background: Platform trials enable faster, less expensive, and more efficient clinical readouts by evaluating multiple products and combinations. This study explores the willingness of pharmaceutical companies to put experimental drugs into a platform trial, and examines the drivers and barriers to their participation. Methods: The I-SPY2 (Investigation of Serial studies to Predict YourTherapeutic Response with Imaging And molecular anaLysis2) pre-competitive collaborative platform trial was used as a case study to elucidate the motivation and constraints of the pharmaceutical industry. Rogers’ Diffusion of Innovation theory (ISBN 0029266718) was used as theoretical framework, primary interviews were conducted with 14 executive level representatives from 9 different pharmaceutical companies, and data was analyzed in ATLAS.ti to derive the influence factors. The I-SPY2 neo-adjuvant breast cancer platform trial is a partnership of 10 pharmaceutical and 5 biotech companies, alongside 18 academic institutions, patient advocates and the FDA, under the sponsorship of the non-profit Quantum Leap Healthcare Collaborative. I-SPY2 has entered 15 investigational agents of which 10 have completed evaluation and 5 are still ongoing. Results: Two factors were critical drivers for whether pharmaceutical companies were willing to put experimental drugs into a platform trial: the registration status of the agent and whether or not it was the primary indication for treatment. Drugs were more likely to be considered for these types of trials if other registration trials were completed or in progress and if the primary indication for the agent was in a different cancer organ type (e.g. not breast). Four types of perspectives positively influenced pharmaceutical company to participation: a gain in efficiency of drug evaluation, the opportunity for knowledge generation, innovativeness of the trial design, and the expertise and reputation of the consortium. Primary barriers that reduced the chance of participation included a loss of control over the evaluation of the drug and the organizational and governance structure. No significant differences were identified between company size and experience in a therapeutic area. Finally, regulatory guidelines specified by the FDA and EMEA as well as payer engagement were the most significant influence factors which could increase pharmaceutical company’s future participation in platform trials. Conclusion: This is the first study to examine the drivers and barriers to pharmaceutical company participation in platform trials and provides insight for why innovative companies participate in these groundbreaking studies. The FDA has expressed strong interest in promoting platform trials because of their efficiency and knowledge generation. Working to integrate a registration component as part of adaptive platform trials is likely to be a key driver of successful future adoption. Citation Format: Jurr M. van Ramshorst, Laura J. van 't Veer, Dave Mandelkern, Laura J. Esserman, Daniel Dornbusch. Factors driving industry participation in the collaborative I-SPY2 platform trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3362.

BACKGROUND: Previous studies have suggested that breast cancer risk factors are associated with estrogen receptor (ER) and progesterone receptor (PR) expression status of the tumors. METHODS: We pooled tumor marker and epidemiological risk factor data from 35,568 invasive breast cancer case patients from 34 studies participating in the Breast Cancer Association Consortium. Logistic regression models were used in case-case analyses to estimate associations between epidemiological risk factors and tumor subtypes, and case-control analyses to estimate associations between epidemiological risk factors and the risk of developing specific tumor subtypes in 12 population-based studies. All statistical tests were two-sided. RESULTS: In case-case analyses, of the epidemiological risk factors examined, early age at menarche (≤12 years) was less frequent in case patients with PR(-) than PR(+) tumors (P = .001). Nulliparity (P = 3 × 10(-6)) and increasing age at first birth (P = 2 × 10(-9)) were less frequent in ER(-) than in ER(+) tumors. Obesity (body mass index [BMI] ≥ 30 kg/m(2)) in younger women (≤50 years) was more frequent in ER(-)/PR(-) than in ER(+)/PR(+) tumors (P = 1 × 10(-7)), whereas obesity in older women (>50 years) was less frequent in PR(-) than in PR(+) tumors (P = 6 × 10(-4)). The triple-negative (ER(-)/PR(-)/HER2(-)) or core basal phenotype (CBP; triple-negative and cytokeratins [CK]5/6(+) and/or epidermal growth factor receptor [EGFR](+)) accounted for much of the heterogeneity in parity-related variables and BMI in younger women. Case-control analyses showed that nulliparity, increasing age at first birth, and obesity in younger women showed the expected associations with the risk of ER(+) or PR(+) tumors but not triple-negative (nulliparity vs parity, odds ratio [OR] = 0.94, 95% confidence interval [CI] = 0.75 to 1.19, P = .61; 5-year increase in age at first full-term birth, OR = 0.95, 95% CI = 0.86 to 1.05, P = .34; obesity in younger women, OR = 1.36, 95% CI = 0.95 to 1.94, P = .09) or CBP tumors. CONCLUSIONS: This study shows that reproductive factors and BMI are most clearly associated with hormone receptor-positive tumors and suggest that triple-negative or CBP tumors may have distinct etiology.

A method based on the reverse transcriptase-polymerase chain reaction (RT-PCR) was developed that allows the determination of relative mRNA expression levels in fine-needle aspirates from human tumors. The method was developed for the c-erbB-2 gene, using the porphobilinogen deaminase (PBGD) gene as an internal standard. It was validated for mRNA isolated from cell lines and for material obtained by fine-needle aspiration from human breast cancer. Gene expression levels were determined by measuring the activity of radiolabeled RT-PCR-amplified gene-specific bands with a phosphor imager. At least four points are measured on the log-linear part of the amplification cycle versus signal intensity curves, and subsequently the distance between the curves of the gene of interest and that of an internal standard gene is used to calculate the relative expression levels. The method worked equally well with the BRCA1 gene, illustrating that it can be generalized to other genes. The method is suitable to measure or monitor semiquantitively gene expression levels in accessible human tumors in situ.

Ataxia-telangiectasia (A-T) is an autosomal recessive neurodegenerative disorder with multisystem involvement and cancer predisposition, caused by mutations in the A-T mutated (ATM) gene. To study genotypephenotype correlations, we evaluated the clinical and laboratory data of 51 genetically proven A-T patients, and additionally measured ATM protein expression and kinase activity. Patients without ATM kinase activity showed the classical phenotype. The presence of ATM protein, correlated with slightly better immunological function. Residual kinase activity correlated with a milder and essentially different neurological phenotype, absence of telangiectasia, normal endocrine and pulmonary function, normal immunoglobulins, significantly lower X-ray hypersensitivity in lymphocytes, and extended lifespan. In these patients, cancer occurred later in life and generally consisted of solid instead of lymphoid malignancies. The genotypes of severely affected patients generally included truncating mutations resulting in total absence of ATM kinase activity, while patients with milder phenotypes harbored at least one missense or splice site mutation resulting in expression of ATM with some kinase activity. Overall, the phenotypic manifestations in A-T show a continuous spectrum from severe classical childhood-onset A-T to a relatively mild adult-onset disorder, depending on the presence of ATM protein and kinase activity. Each patient is left with a tremendously increased cancer risk. Hum Mutat 33:561571, 2012. (C) 2011 Wiley Periodicals, Inc.

We undertook a systematic approach to identify breast cancer (BC) marker genes with molecular assays and evaluated these marker genes for the detection of minimal residual disease in peripheral blood mononuclear cells (PBMCs).We used serial analysis of gene expression to identify a range of genes that were expressed in BC but absent in the expression profiles of blood and bone marrow cells. Next, we evaluated a panel of four marker genes (p1B, PS2, CK19, and EGP2) by real-time quantitative PCR in 103 PBMC samples from patients with metastatic BC (stage III/IV) and in 96 PBMC samples from healthy females.Increased marker gene expression of at least one marker was seen in 33 of 103 patients. Using quadratic discriminant analysis including all four marker genes, we determined a discriminant value with 29% positivity in the BC patient group that did not yield false positive results among the healthy females.Real-time PCR for the simultaneous expression of multiple cancer-specific genes may ensure the specificity required for the clinical application of mRNA expression-based assays for occult tumor cells.

32 Background: Biology has become the main driver of breast cancer therapy. Intrinsic biological subtypes by gene expression profiling have been identified. Pathology can be used to define surrogates of these subtypes but these are not always concordant, which may lead to different treatment plans. We investigated the concordance between BluePrint (BP) + MammaPrint (MP) (micro array based) breast cancer subtypes and pathological surrogates (based on ER, PR, HER2 and Ki67). Contrary to the Perou gene set (evolved into PAM50), BluePrint was trained using pathological data. Methods: Using available data (centrally assessed pathology and genomic) from the MINDACT pilot phase (Rutgers et al 2011) 621 tumors were analyzed. Two pathology classifications were used: one with 4 categories and one with 5 categories (Goldhirsch et al 2011). Based on BP 3 subtypes are formed: Luminal, HER2 and Basal. The Luminal subtype is further split into Luminal A (MP low risk) and Luminal B (MP high risk). Results: See table. Conclusions: All pathological Basal cases are BP Basal, apart from 1 BP HER2 case. Of the BP Basal cases, 15 are not pathological Basal: 1 is Luminal A, 11 are Luminal B (of which 8 are IHC ER/PR borderline (≥1% and < 10%)) and 3 are HER2. All pathological Luminal (A & B) that are BP HER2 are HER2- by TargetPrint. 25 of the 26 pathological HER2+ that are BP Luminal A are ER+. Most discordant cases are seen within the Luminal subtype, indicating that Ki67 discriminates Luminal A vs. B differently than MammaPrint does. The observed subtype discrepancies reveal potential important impact for treatment-decision making. MINDACT will provide important information. [Table: see text]

A 42-year-old man presented with a locally invasive cortical thymoma. Before chemotherapy was commenced 36 months after presentation, an unusual peripheral lymphocytosis of 19 x 10(9)/l had slowly developed over time. After the first course of chemotherapy, the lymphocytosis showed a sharp decline to normal absolute cell numbers and subsequently remained at normal levels. Currently, the patient is in stable partial remission and doing well. Immunophenotypic analysis showed a mature T-cell phenotype with 78% TcR-a beta and 16% TcR-gamma delta in the absence of an immature component. Pretreatment Southern blot analysis of peripheral blood mononuclear cells showed an oligoclonal pattern with 13-20 rearranged fragments of different intensity for the TcR beta-gene. TcR gamma also showed a pattern compatible with an oligoclonal proliferation. After treatment, after normalization of absolute blood counts, the distribution of T-cell subsets still showed a slightly aberrant pattern. Immunophenotypic analysis of a blood sample taken 6 months later, also at normal absolute cell counts, showed an increase of thymocytes as well as of mature T cells with a polyclonal pattern on Southern blot analysis. These findings may be interpreted as the result of aberrant positive and negative selection and development of thymocytes in the microenvironment of neoplastic thymic epithelial cells and clonal selection through continuous peripheral stimulation. Moreover, this case stresses the importance of integrated interpretation of clinical, morphological, immunophenotypical, and molecular data to gain insight in unusual clinical problems.