Abstract P2-09-16: Tumor infiltrating lymphocytes (TILs) as a biomarker for resistance to palbociclib (Pal) in the NeoPalAna trial

Background: Cyclin-dependent kinase (CDK) 4/6 inhibitors improve disease free survival for patients (pts) with advanced hormone receptor positive (HR+) and HER2 negative (HER2-) breast cancer (BC). However, there are no established biomarkers that identify sensitive versus resistant tumors. We have recently reported results from the phase II neoadjuvant NeoPalAna trial (NCT01723774 ) which demonstrated that Pal enhanced the anti-proliferative activity when added to anastrozole (Ana) monotherapy in HR+HER2- BC. Interestingly, a small group of pts (15%) were resistant to Pal, exhibiting persistent tumor cell proliferation (Ki67 >2.7%) on Ana plus Pal. Several studies have evaluated the prognostic and predictive importance of TILs in BC, particularly in triple negative and HER2+ subtypes. Studies evaluating TILs in HR+ BC is limited. Here we evaluated the utility of TILs in identifying Pal-resistant tumors.

Methods: Serial biopsies were collected from pts at 4 time points: baseline (BL), cycle 1 day 1 (C1D1) following 28 days of Ana monotherapy, cycle 1 day 15 (C1D15) at 2 weeks post the addition of Pal, and at surgery (Surg). TILs were evaluated using published recommendations by the TILs international working group. Agilent 4X44 whole genome gene expression arrays performed on fresh frozen biopsies at BL, C1D1, and C1D15 were analyzed for pathways and gene signatures that differentiate Pal-resistant (Pal-r) (C1D15 Ki67 >2.7%) from Ana-sensitive (Ana-s) (C1D1 Ki67 ≤2.7%) or Pal- sensitive (Pal-s) (C1D1 Ki67 >2.7% but C1D15 Ki67 ≤2.7%) tumors defined by Ki67 response. TILs at each time point were pairwise compared between response groups using Wilcoxon rank sum test and Benjamini-Hochberg adjusted two-sided p-values were reported. Change between 2 time points within a response group was evaluated by Wilcoxon signed rank test.

Results: The TILs were significantly different between Ana-s and Pal-s groups [BL p=0.03, C1D1 p=0.01, C1D15 p=.02], as well as between Ana-s and Pal-r groups [BL p=0.03, C1D1 p=0.04, C1D15 p=0.02]. Overall Pal-r samples showed the highest TILs at all time points, while Ana-s samples showed the lowest TILs. There was no significant change between time points.

Elevated TILs in Pal-r group was further supported by microarray gene expression analysis which demonstrated a large group of genes associated MHC Class-I (15+ HLA and proteasome genes) as well as Immune–inflammation pathways (18+ T cell & lymphocyte markers, signaling genes) being up regulated at BL in the Pal-r group (n=5). Pal-r samples showed a similar trend in subsequent time points although the numbers of samples were small. Many genes within this immune-inflammatory group of genes were correlated with Ki67 change at C1D15 from BL, suggestive of a potential relationship with resistance.

Conclusions: Our data shows Pal resistance was consistently associated with higher TILs at BL and post treatment, which correlated with increased expression of inflammation-immune group genes. TILs may have utility to be used as a biomarker to identify Pal resistant BC. Our data is hypothesis generating and raises the possibility of immune therapy to overcome Pal resistance in BC.

Citation Format: Sanati S, Barve R, Luo J, Hoog J, Head R, Ellis M, Ma C. Tumor infiltrating lymphocytes (TILs) as a biomarker for resistance to palbociclib (Pal) in the NeoPalAna trial [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 P2-09-16.

Abstract P2-09-19: Genomic biomarker for resistance to palbociclib in the NeoPalAna trial

Background: Cyclin-dependent kinase (CDK) 4/6 inhibitors are being evaluated in the adjuvant setting for patients with resected early stage hormone receptor positive (HR+) and HER2 negative (HER2-) breast cancer (BC). However, biomarkers that predict benefit from this class of agents are unknown. We have recently reported results from the phase II neoadjuvant NeoPalAna trial which demonstrated that palbociclib (Pal) enhanced the anti-proliferative activity when added upon anastrozole (Ana) monotherapy in estrogen receptor (ER) positive and HER2 negative breast cancers. Interestingly, a small group of patients was resistant to Pal, exhibiting persistent tumor cell proliferation (Ki67 >2.7%) on the combination of Ana and Pal. In this study, we evaluated the utility of a research algorithm for the 70-gene signature (70-GS) in identifying Pal resistant versus sensitive patients. Methods: Serial biopsies were collected from patients at four treatment timepoints: baseline (BL), cycle 1 day 1 (C1D1) following 28 days of Ana monotherapy, cycle 1 day 15 (C1D15) at 2 weeks post the addition of Pal, and at surgery (Surg). RNA was extracted from frozen tumor biopsies at each timepoint and run on Agilent full genome microarrays (GSE93204) at Washington University. As an exploratory analysis, genes from the GPL8253 array that match the 70-GS were used to calculate a research approximation of the 70-GS index (r-GS). The distribution of the r-GS across Ki67 response groups was evaluated. Results: Ki67 had previously been measured at each timepoint, and used to classify patients as being either Ana-sensitive (C1D1 Ki67 ≤2.7%), Pal-sensitive (C1D1 Ki67 >2.7%, C1D15 Ki67 ≤2.7%), or Pal-resistant (C1D15 Ki67 >2.7%). The r-GS was differentially regulated between sensitive (AI or Pal) and Pal-resistant groups at BL (p=0.012), C1D1 (p=0.039), and C1D15 (p=0.022). The r-GS values varied widely across patients at BL, and generally became more positive (more low risk) with treatment. There was no correlation between Ki67 levels and r-GS. Furthermore, gene expression analysis was performed to elucidate the difference between Pal-sensitive vs. Pal-resistant patients, and Ana-sensitive vs. Pal-sensitive patients. Conclusions: While on-treatment Ki67 indicated drug responsiveness, baseline r-GS significantly stratified patients into sensitive (Ana or Pal) versus Pal-resistant groups in the neoadjuvant setting. This preliminary finding suggests that the 70-GS may have clinical utility in identifying patients resistant to Pal for future studies. Additionally, results of the gene expression analysis may help to further develop genomic biomarkers for Pal and Ana sensitivity and resistance.

Citation Format: Hoog JW, Treece T, Blumencranz L, Audeh W, Sanati S, Ellis MJ, Ma CX. Genomic biomarker for resistance to palbociclib in the NeoPalAna trial [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 P2-09-19.

Abstract P5-04-02: Serum thymidine kinase 1 activity as a pharmacodynamics marker of cyclin-dependent kinase 4/6 inhibition in patients with early stage breast cancer receiving neoadjuvant palbociclib

Background: Thymidine kinase 1 (TK1) is a fundamental enzyme in DNA synthesis. TK1 expression is E2F-dependent and peaks in the S-phase of the cell cycle. In preclinical studies, inhibition of cyclin-dependent kinase (CDK) 4/6 led to dose dependent reduction of TK1 activity in cultured media. We hypothesized that serum TK1 could serve as a non-invasive surrogate marker of cell proliferation in patients (pts) receiving CDK4/6 inhibitors. In this study, we examined serum TK1 activity from breast cancer (BC) pts enrolled on a neoadjuvant study of palbociclib (Palbo) plus anastrozole (A), for changes induced by Palbo, and correlated with changes in tumor Ki67.

Methods: In this phase II neoadjuvant study, 50 pts with clinical stage II or III estrogen receptor positive (ER+) HER2- BC, received A (in combination with goserelin if premenopausal) alone for 28 days in cycle 0 (C0), followed by the addition of Palbo (125 mg daily on days 1-21) on cycle 1 day 1 (C1D1) for 4 28-day cycles (C1 to C4) unless C1D15 tumor Ki67>10%, in which case pts went off study. Following completion of cycle 4, A was continued for another 3-5 weeks to allow Palbo washout prior to surgery, except in 8 pts who received an additional 10-12 days of Palbo immediately prior. Blood and tumor biopsies were collected at 4 time points: baseline, C1D1, C1D15, and surgery. Serum TK1 activity was measured using the highly sensitive Divitum™ assay according to the Divitum™ Instructions for use (Biovica, Sweden). Tumor Ki67 IHC was performed at the Washington University AMP laboratory using the CONFIRM anti-Ki67 rabbit monoclonal antibody (clone 30-9), and pathologist guided image analysis.

Results: There was no statistically significant difference in TK activity between baseline and C1D1 serum samples (Table 1). However, serum TK activity decreased significantly from C1D1 to C1D15 following the addition of Palbo and increased significantly from C1D15 to surgery following Palbo washout (Table 1), indicating a significant effect of Palbo on TK activity. At C1D15, TK activity was below the detection limit of 20 Du/L in 44 of 48 pts, and was at low levels (24, 26, 26, and 58 Du/L) in the remaining 4 pts, indicating a profound effect by Palbo. Interestingly, the TK activities of the 4 pts with tumor Ki67 >10% at C1D15 were all below 20 Du/L, suggesting the possibility of tumor cell proliferation independent of CDK4/6 inhibition.

The sensitivity and specificity of change (increase/decrease) in serum TK activity to predict tumor Ki67 (increase/decrease) induced by Palbo were 83% (19/23, 95%CI: 66-99%) and 93% (26/28, 95%CI: 83%-100%), respectively. The Kappa statistic was 0.761 (P<0.001), indicating substantial agreement between the two tests.

Conclusions: Serum TK1 activity may serve as a pharmacodynamics marker of CDK4/6 inhibition and further investigation is warranted.

Table 1. Serum TK1 and tumor Ki67 Serum TKKi67 Median (IQR) (Du/L)NMedian (IQR) (%)NBaseline46 (25-73)4824.34% (11.92%-35.43%)45Cycle 1 day 143 (27.5-98)495.37% (2.49%-13.59%)*45Cycle 1 day 1520 (20-20)*480.78% (0.23%-1.05%)*45Day of surgery136.0 (37.5-259)*378.33% (2.25%-23.03%)*34*P<0.001 compared to the preceding time point.

Citation Format: Liu N, Thomas S, Luo R, Hoog J, Suh EM, Bergqvist M, Neumüller M, Guo Z, Vij K, Sanati S, Ellis M, Ma C. Serum thymidine kinase 1 activity as a pharmacodynamics marker of cyclin-dependent kinase 4/6 inhibition in patients with early stage breast cancer receiving neoadjuvant palbociclib [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-04-02.

Abstract P1-07-11: Tumor genomic profiling of triple negative breast cancer during neoadjuvant chemotherapy: Results from a prospective trial of carboplatin and docetaxel

Background-The clonal evolution and effect of neoadjuvant chemotherapy on the mutational landscape of triple negative breast cancer (TNBC) is unknown. Inability to eradicate TNBC may be due to clonal progression and selection of cells fundamentally resistant to chemotherapy.In this study, we sought to decipher the genomic architecture of TNBC serially during neoadjuvant chemotherapy to distinguish pre- versus post-chemotherapy genotypes.

Methods-Tumor specimens were obtained from patients with stages II and III TNBC enrolled on an ongoing prospective neoadjuvant co-clinical trial (NCT02124902). Patients have a research biopsy at baseline, cycle 1 day 3 (optional), and at definitive surgery for those with residual disease. Patients are treated with docetaxel 75mg/m2 and carboplatin AUC6 cycled every 3 weeks X six cycles. Definitive surgery is 3-5 weeks after chemotherapy. The primary endpoint is pathologic complete response rate. Correlative studies include development of patient derived xenografts, evaluation of genomic signatures of resistance and response, and comparison of chemotherapy responses between xenografts and host patients. Five patients' serial tumor samples and germline DNA were studied by exome and transcriptome sequencing. Three of these patients had an additional on-treatment sample at cycle 1 day 3. Two patients lacked residual disease samples- one was not banked and the other could not be accurately genotyped due to low cellularity. The median sequencing depth was 90.13x. Sequencing was performed on either fresh frozen or formalin-fixed paraffin-embedded samples with high cellularity (≥50%). After identifying somatic mutations in each tumor series, we evaluated whether each mutation was persistent, emergent, or cleared by comparing pre- and post-treatment (and when possible, on-treatment) samples.

Results-All five patients had response to neoadjuvant chemotherapy based on caliper-based and pathologic (residual cancer burden I or II) measurements. All residual disease remained TNBC by standard immunohistochemistry and all samples were basal-like from PAM50 gene expression analysis. We identified 908 somatic mutations, including the expected variants in TP53 which persisted in all post-treatment samples. Non-silent somatic variants were identified in other breast cancer-related genes, including GATA1, FBXO11, PIK3R1, AXIN2, ARID1B, BRCA2, and RBCC1. In spite of the clinico-pathologic evidence of response, we observed little change in clonal architecture, as derived from the purity-corrected variant allele fractions between baseline, cycle 1 day 3, and post-chemotherapy samples. Copy number alterations were likewise stable and transcriptional-based assessment indicated that patterns of mutant allele expression in driver genes were retained throughout the course of treatment.

Conclusion-In TNBC patients undergoing neoadjuvant platinum-based chemotherapy, there were no apparent shifts in the prevalence of known breast cancer specific somatic variants during or after chemotherapy. Despite pathologic response, core genomic features appear to be preserved in TNBC patients with residual disease following chemotherapy, likely accounting for high rates of relapse in these patients.

Citation Format: Ademuyiwa FO, Miller CA, Li T, Sanati S, Ma CX, Weilbaecher K, Ellis MJ, Mardis ER. Tumor genomic profiling of triple negative breast cancer during neoadjuvant chemotherapy: Results from a prospective trial of carboplatin and docetaxel [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-07-11.

Abstract S6-05: A phase II trial of neoadjuvant palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, in combination with anastrozole for clinical stage 2 or 3 estrogen receptor positive HER2 negative (ER+HER2-) breast cancer (BC)

Background

ER+ BC is associated with activated CDK4/6. The CDK4/6 inhibitor palbociclib (P) markedly improves time to progression in advanced ER+HER2- BC. We conducted a neoadjuvant phase II trial to determine the activity of P in primary breast cancer as a prelude to adjuvant studies.

Methods

To assess molecular changes induced by anastrozole (A) or P+A, patients (pts) were treated initially with A alone (1mg PO daily) for 28 days in cycle 0 (C0) before the addition of P (125mg PO daily on D1-21 each cycle) on C1D1. P+A was administered for 4 28-day cycles followed by C5 with A alone for 2-4 weeks (wks) before surgery. P was added in C5 for 10-12 days immediately prior to surgery in the last 20 pts enrolled to assess molecular changes induced by A, either alone or in combination with P immediately prior to surgery, in resected tumor. Goserelin was added in premenopausal pts.

Research tumor biopsies were obtained at baseline, C1D1, and C1D15. Central Ki67 analysis was performed at all timepoints, those with Ki67 >10% at C1D15 went off study treatment.

The primary endpoint was complete cell cycle arrest (CCA), defined as Ki67 <2.7%, at C1D15. Patient stratification was based on PIK3CA mutation status with an initial focus on PIK3CA wild type (WT) disease. Pts with PIK3CA mutant (Mut) tumors enrolled to a separate cohort. A sample size of 33 pts in the PIK3CA WT cohort was chosen based on the Fleming's single-stage phase II design to test the hypothesis that P+A leads to > 50% improvement over A in CCA rate on C1D15 biopsy (44% with A alone based on historical data, vs 66% with P+A, power = 0.8, alpha=0.05). The primary endpoint is met if >20 pts achieved CCA in this cohort.

Correlative endpoints included assessment of markers of proliferation, apoptosis, senescence, Rb, gene expression microarray, intrinsic subtype, and next generation sequencing of 83-gene panels, which will be reported at the meeting.

Results

Between 4/23/2013 and 4/24/2015, 50 pts (33 PIK3CA WT, 11 PIK3CA Mut, 2 pending, 4 tissue quantity or quality not sufficient for sequencing (QNS)) were enrolled to the study. Median age was 57.5 (range: 34.1–79.6) years. Four pts, all with WT PIK3CA, went off study due to Ki67 >10% on C1D15 biopsy, 26 pts completed treatment and surgery, 1 refused surgery, 3 withdrew study treatment in C1, and 16 continued to receive study drug (2 in C0, 3 in C1, 4 in C2, 5 in C3, 1 in C4, and 1 in C5). Among the 40 pts currently evaluable for the primary endpoint (C1D15 Ki67), CCA occurred in 34 (85%) pts, including 9 of 9 (100%) PIK3CA Mut, 22 of 28 (78.5%) WT, and 3 of 3 QNS pts. Preliminary analysis of available data indicated a significantly lower Ki67 value after 2 wks of P+A (C1D15) compared to that on A alone (C1D1) (p=0.034, n=18).

Conclusion

This study met the primary endpoint demonstrating that P+A is a highly effective anti-proliferative combination. The sequential biopsy design clearly demonstrated that P+A increased cell cycle control over A alone. P+A was effective regardless of PIK3CA mutation status and these results support the evaluation of this combination in the adjuvant setting for ER+HER2- BC.

Citation Format: Ma CX, Gao F, Northfelt D, Goetz M, Forero A, Naughton M, Ademuyiwa F, Suresh R, Anderson KS, Margenthaler J, Aft R, Hobday T, Moynihan T, Gillanders W, Cyr A, Eberlein TJ, Hieken T, Krontiras H, Hoog J, Han J, Guo Z, Vij K, Mardis E, Al-Kateb H, Sanati S, Ellis MJ. A phase II trial of neoadjuvant palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, in combination with anastrozole for clinical stage 2 or 3 estrogen receptor positive HER2 negative (ER+HER2-) breast cancer (BC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr S6-05.

Abstract P4-09-19: Comprehensive multiplatform molecular profiling identifies potentially targetable biomarkers in malignant phyllodes tumors of the breast

Introduction: Malignant phyllodes tumors are rare breast malignancies (0.1% of all breast tumors) with limited effective treatment options for recurrent and metastatic disease. Recent trials indicated a potential for anti-angiogenic therapy in soft tissue sarcomas, which led us to investigate these pathways.

Materials and Methods: Thirty-five malignant phyllodes tumors (including two cases with matched primary and metastatic tumors) were profiled using gene sequencing (Next-generation and Sanger), gene copy number analysis (in-situ hybridization), whole genome RNA expression, and protein expression (immunohistochemical assay).

Results: RNA microarray assay showed consistent over-expression of genes involved in angiogenesis including VEGFA, Angiopoietin2, VCAM1, PDGFRA, PTTG1, and CYP3A5 in all cases analyzed (n=5). No mutations in KDR (VEGFR2) were detected (0/26). EGFR protein overexpression was observed in 25/26 (96%) of cases with amplification of the EGFR gene in 8 cases (33%). EGFR gene mutations were identified in 2 cases (8%) including one case with presumed pathogenic V774M mutation and one case with EGFRvIII mutation. The most common mutations included those of TP53 (50%) and PIK3CA (15%) while other mutations (BRCA1, BRCA2, RET, CDH1, MLH1, ATM) were rare affecting single phyllodes cases. Two cases with matched primary and metastatic cancers harbored the same mutations in both sites (PIK3CA/KRAS and RB1 gene mutations, respectively).

Conclusions: Comprehensive multiplatform profiling approach to phyllodes tumors identifies various molecular alterations of which some are potentially actionable. Our data suggests that anti-angiogenic therapy may also be effective in patients with malignant phyllodes tumor. Evaluation of EGFR pathway discovered consistent protein over-expression but rare activating mutations, which necessitates refinement in patient selection targeting these pathways.

Citation Format: Gatalica Z, Vranic S, Ghazalpour A, Xiu J, Ocal I, McGill J, Bender R, Discianno E, Sanati S, Reddy S, Pockaj B. Comprehensive multiplatform molecular profiling identifies potentially targetable biomarkers in malignant phyllodes tumors of the breast. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-09-19.

Abstract P5-13-04: A phase II neoadjuvant trial of MK-2206, an AKT inhibitor, in combination with anastrozole for clinical stage 2 or 3 PIK3CA mutant estrogen receptor positive HER2 negative (ER+HER2-) breast cancer (BC)

Background

Activating mutations in PIK3CA occur in approximately 40% ER+BC. MK-2206 (M), a pan-AKT inhibitor, induced apoptosis of ER+ BC under estrogen deprivation in preclinical studies. We conducted this neoadjuvant trial to determine the pathologic complete response (pCR) rate of M plus anastrozole (A) for PIK3CA mutant (Mut) ER+ BC.

Methods

This single arm open label study of M+A used a 2-stage Simon phase II design (stage 1, n=16; stage 2, n=13, alpha=0.10, power=0.90) to test whether pCR rate <1% (based on historical data with A alone), against the alternative that pCR rate ≥15% in PIK3CA Mut ER+ BC. At least 1 pCR in stage 1 was required to proceed to stage 2.

Eligible patients (pts) with clinical stage II or III ER+HER2- BC were pre-registered and proceeded to a research tumor biopsy for PIK3CA sequencing, followed by treatment with daily A monotherapy for 28 days (cycle 0). Pts with PIK3CA Mut BC were subsequently registered, underwent a second biopsy, and started M (150mg PO weekly) with daily A on cycle 1 day 1 (C1D1) for a maximum of four 28-day cycles followed by surgery. Goserelin was added for premenopausal pts. A tumor biopsy on C1D17, 17 days post the start of M, was performed. Those with C1D17 Ki67 >10% discontinued study treatment. pCR was defined as no invasive cancer in the breast and the lymph nodes. Tumor specimens collected at all timepoints are being analyzed for markers of proliferation, apoptosis, and PI3K pathway activity, gene expression microarray, intrinsic subtypes, and next generation sequencing of 83 genes.

Results

Of the 51 pts pre-registered, 35 pts did not register due to no PIK3CA mutation (n=22), inadequate specimen for testing (n=6), physician/pt decision (n=7). The remaining 16 pts (median age: 58, range: 40-77 years) received combination therapy. Three pts did not complete 4 cycles due to C1D17 Ki67 >10% (n=2) and intolerability (grade (Gr) 4 transaminase elevation in C1, n=1). Other severe toxicities possibly related to M included Gr 3 rash (25%) and pruritus (12.5%). Of the 13 pts completed study therapy and underwent surgery, all had residual disease in the breast and 7 also had positive nodes. Table 1 summarized changes in Ki67 during treatment.

ComparisonsnAbsolute changes in Ki67 median (range)Wilcoxon signed rank p-valueC1D1 relative to pre-registration11-17.0% (-49.8 to 4.1%)0.0020C1D17 relative to pre-registration14-16.4% (-51.4 to 4.1%)0.0004C1D17 relative to C1D112-1.5% (-18.6 to 15.8%)0.9697C1D1, biopsy post 28 days of A alone; C1D17 biopsy post 17 days on combination therapy

Although Ki67 levels post A monotherapy (C1D1) or M+A (C1D17) were significantly lower than that of pre-registration samples, Ki67 did not differ between C1D17 and C1D1 samples. Other correlative studies are ongoing and results will be presented.

Conclusion

Despite the small sample size, biomarker analysis on serial biopsy specimens demonstrated that M+A is unlikely to be more effective than A alone in PIK3CA Mut ER+ BC. This trial demonstrated the feasibility of genomic sequencing for pt selection and the value of a small, well-designed proof-of-principle neoadjuvant trial for the evaluation of targeted agents.

Citation Format: Ma CX, Suman VJ, Goetz M, Northfelt D, Burkard M, Ademuyiwa F, Naughton M, Margenthaler J, Aft R, Gray R, Tavaarwerk A, Wilke L, Haddad T, Moynihan T, Loprinzi C, Hieken T, Hoog J, Guo Z, Han J, Vij K, Mardis E, Sanati S, Al-Kateb H, Doyle L, Erlichman C, Ellis MJ. A phase II neoadjuvant trial of MK-2206, an AKT inhibitor, in combination with anastrozole for clinical stage 2 or 3 PIK3CA mutant estrogen receptor positive HER2 negative (ER+HER2-) breast cancer (BC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-13-04.