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Background: KEYNOTE-522 was a randomized, double-blind, placebo-controlled phase 3 trial which resulted in the FDA approval of pembrolizumab with neoadjuvant chemotherapy for patients (pts) with newly diagnosed, high-risk, early-stage triple negative breast cancer (TNBC). Given the improvement in pathological complete response (pCR) and event-free survival rates, this regimen has emerged as standard-of-care (SOC) therapy. Adverse events in pts on this treatment regimen in clinical practice is unknown and understanding the real-world toxicity of this regimen is critical. Methods: In this IRB approved retrospective, single-center study we examined pts with early-stage TNBC who received planned treatment per KEYNOTE-522 per SOC from 2021-present. This regimen includes a year of pembrolizumab combined with 4 cycles of neoadjuvant carboplatin/paclitaxel followed by 4 cycles of doxorubicin/cyclophosphamide. Number and length of treatment delays, treatment related toxicities of all grades, and pCR rate were collected from the electronic medical record. Results: Of the 87 identified pts, 2 were excluded due to locally recurrent or metastatic disease and 6 did not receive immunotherapy due to concerns for toxicity or patient preference. Of the 79 pts who initiated treatment with chemotherapy and immunotherapy, median age of the cohort was 52 (27-77). 9 pts had a BRCA1 mutation and 1 pt had a BRCA2 mutation. 41 (51.9%) had T1-2 disease and 38 (48.1%) had T3-4 disease. 37 (46.8%) pts had N0 disease and 42 (53.2%) had N1-3 disease. 15 pts had baseline comorbidities, including heart disease, kidney disease, type II DM, and/or peripheral neuropathy. 68 pts (86.1%) had baseline ECOG 0, 9 (11.4%) had ECOG 1, and 2 (2.5%) had ECOG 2. At the time of analysis, 70 pts (88.6%) were receiving active treatment, of which 47 (67.1%) had completed ≥50% of the planned neoadjuvant therapy. Of pts completing ≥50% of planned neoadjuvant therapy and pts off therapy (N=56), 31 (55.4%) had 1 or more hospitalizations and 23 (41.1%) had 1 or more emergency room visits. 30 pts had treatment delays (53.6%) and 21 pts (37.5%) had dose reductions. Rates of adverse events are presented in Table 1. Of the 79 analyzed pts, 35 have undergone surgery. pCR rate was 45.7% (N=16). 8 (22.9%) pts had RCB-I, 4 (11.4%) pts had RCB-II, 3 (8.6%) pts had RCB-III, and 4 (11.4%) pts had residual disease without RCB calculation. Updated analysis will be included at time of presentation. Conclusions: In this single-center retrospective study of pts receiving chemoimmunotherapy for TNBC, we found higher rates of grade 3 toxicity, including nausea, fatigue, neutropenia, diarrhea, peripheral neuropathy, and hypothyroidism, and lower pCR rate than was reported in the KEYNOTE-522 trial. This may reflect a more heterogeneous population of pts treated in routine clinical practice who are typically less fit than pts on clinical trials. Additionally, pts in this study had higher T stages (48.1% with T3-4 disease vs 26.0% in trial) and node positive disease (53.7% with N1-3 disease vs 48.8% in trial). Limitations include immaturity of data and small sample size; however, these data warrant validation through longer-term follow-up and multicenter validation. Adverse Events in pts receiving Keynote-522 regimen as SOC and on clinical trial Citation Format: Mara Hofherr, Jennifer Hedgecorth, Foluso O. Ademuyiwa, Lindsay L. Peterson, Nusayba A. Bagegni, Rama Suresh, Ashley Frith, Ron Bose, Katherine Weilbaecher, Cynthia Ma, Andrew A. Davis, Katherine K. Clifton. Real-world analysis of adverse events of patients with triple negative breast cancer receiving therapy per KEYNOTE-522 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-06-06.

Background: CDK 4/6i have altered the therapeutic landscape of HR+, HER2- MBC, improving progression free and overall survival (PFS and OS) compared to endocrine therapy (ET) alone. Despite durable responses to CDK 4/6i in a large majority of patients, treatment response monitoring in this population has historically included numerous serial blood-based and imaging studies at frequent time points. There is a growing global interest in utilizing novel non-invasive biomarker-driven disease monitoring assessments to improve patient outcomes and reduce health care costs. Thymidine kinase 1 (TK1), a key cell-cycle regulated enzyme important for nucleotide metabolism during DNA synthesis, is regulated by the E2F pathway, downstream of CDK 4/6. Studies have shown that DiviTum® TK1 activity (TKa) may serve as both a prognostic and predictive biomarker of CDK 4/6i treatment response (McCartney et al, Clin Canc Res, 2020; Malorni et al, Eur J Cancer, 2022; Bagegni et al, Breast Cancer Res, 2017). Early TKa suppression within 2 weeks (wk) post CDK 4/6i therapy initiation is associated with improved PFS, suggesting a subgroup of patients who may be able to de-escalate imaging frequency. Elevated TKa at baseline and post CDK 4/6i may identify patients with CDK 4/6i-resistant disease and disease progression (PD) requiring early therapy modification. TK IMPACT is a prospective, single-arm trial designed to assess the impact of incorporation of DiviTum® TKa on a physician’s decision regarding subsequent timing of routine disease monitoring modalities in patients with advanced HR+, HER2- MBC receiving ET plus CDK 4/6i (NCT04968964). Methods: Blood sample collections will be analyzed using DiviTum® TKa at baseline (bl), wk 2, 4, 6, 8, and Q 4 wks thereafter beginning at wk 8 during the first 24-wk time period of study enrollment (+/- 3 days); followed by Q 12 wks thereafter, until PD or 36 months, whichever occurs first. Optional repeat TKa within 2-4 wks (+/-3 days) is permitted in case of rising TKa. Research blood (bl, wk 2, 12, 24, 48, and PD) and optional archival tumor tissue collection at diagnosis and PD will be obtained for correlatives. The investigator will record intended imaging modalities and timing prior to receipt of TKa, followed by documentation of any changes in imaging testing interval after receipt of TKa. Key eligibility criteria include postmenopausal women age ≥18 years with HR+, HER2- MBC, to initiate (Cohort 1) or are currently receiving (≤24 months, Cohort 2) any FDA approved first line ET plus CDK 4/6i with a life expectancy > 6 months. The primary endpoint is any physician-reported intended change in imaging testing interval post TKa by study cohort, within the first 48-wk period of study participation. Key secondary endpoints are concordance rate between TKa values and progression status at first on-study imaging and longitudinal TKa dynamics. Key exploratory endpoints include plasma and tumor tissue-based biomarkers of CDK 4/6i response and resistance. A total of 40 patients will be enrolled (n=20/Cohort). The expected change rate is 20% with a 95% Wilson confidence interval of 0.105~0.248 across all patients and if within each cohort, with a 95% Wilson confidence interval of 0.081~0.416 for N=20. N=40 allows the lower limit of the 95% CI > 10% and that of the N=20 in Cohort 1 to be ~10%, indicating some clinically meaningful influence of TKa progression on patient management. The study is open to accrual and has presently enrolled 5 patients. Citation Format: Nusayba A. Bagegni, Isabella Grigsby, Leslie Nehring, Jingqin Luo, Jennifer Powers Carson, David W. Gibson, Meghan Horvath, Katherine K. Clifton, Foluso O. Ademuyiwa, Rama Suresh, Ashley Frith, Andrew A. Davis, Lindsay L. Peterson, Ron Bose, Amy Williams, Mattias Bergqvist, Cynthia Ma. TK IMPACT: Treatment Monitoring of Hormone Receptor Positive (HR+), HER2 Negative (HER2-) Metastatic Breast Cancer (MBC) Patients Receiving CDK 4/6 Inhibitors (CDK4/6i) with DiviTum® Thymidine Kinase 1 Activity [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT3-11-01.

Background: CDK4/6 inhibitors (CDK4/6i) paired with endocrine therapy (ET) are considered first-line (1L) therapy for patients (pts) with HR+ HER2- advanced breast cancer (aBC). A minority of pts will demonstrate primary resistance to CDK4/6i, as characterized by early progression. Thymidine kinase 1 (TK1) is a cell-cycle regulated enzyme downstream of CDK4/6 and involved in nucleotide metabolism during DNA synthesis. Prior studies have shown TK1 may serve as a biomarker of response to CDK4/6i, with early TK1 activity (TK1a) suppression after initiation of CDK 4/6i therapy associated with improved PFS. Lack of TK1a suppression may be associated with primary resistance to CDK4/6i. In this study, we aim to analyze response to subsequent lines of therapy and overall survival (OS) of pts with early progression on 1L CDK4/6i. Methods: Pts with HR+ HER2- aBC from a phase II trial of an alternative schedule of palbociclib (palbo alt dosing trial NCT 3007979) and from a retrospective palbociclib study were included in this analysis. Pts in the palbo alt dosing trial underwent baseline and C1D15 TK1a analysis after initiation on CDK4/6i. C1D15 TK1a suppression was defined at TK1a < 30 Du/L. Pts in the retrospective palbociclib study included pts receiving palbo as part of their standard of care 1L therapy for HR+ HER2- aBC at Washington University in Saint Louis from 2016 to 2021. Clinical information, including treatment start and stop dates on each of the next-line therapies, were collected from the electronic medical record. PFS was estimated by the treatment duration on a specified treatment regimen. Early progression on CDK4/6i was defined as PFS < 6 mo. Best response was defined as next line of therapy with the numerically longest PFS. OS was defined as time to death from the initiation of CDK4/6i. Results: Of the 54 pts enrolled on the palbo alt dosing trial, 51 pts were evaluable for clinical benefit and 46 pts were evaluable for TK1a suppression rate at C1D15. 7 pts (15.2%) were found without TK1a suppression at C1D15. This lack of TK1a suppression on palbo was associated with a significantly shorter PFS (median PFS=3.1 mo) compared to not reached in pts with TK1a suppression at C1D15. We conducted clinical analysis on N=26 pts who exhibited early progression on CDK4/6i which included 10 pts from the palbo alt dosing trial and 16 from the retrospective study. The average subsequent line of therapies in this cohort was 3, with the most common second line (2L) therapy being chemotherapy (N=17, 65.4%) and ET (N=8, 30.8%). The median PFS for pts receiving 2L chemotherapy and ET was 4.09 mo and 3.64 mo, respectively. 10 pts received both chemotherapy and ET with 7 (70.0%) achieving best response with chemotherapy compared to 3 pts (30.0%) who achieved best response with ET. The median OS for the cohort was 14.6 mo. Conclusions: Early progression on CDK4/6i is associated with a particularly poor prognosis. In our cohort, the median OS was far below the expected median OS for pts receiving 1L palbo as reported in the PALOMA-2 trial (14.6 mo vs 53.9 mo). Early progression on CDK4/6i is associated with more aggressive disease which may respond more favorably to chemotherapy, as demonstrated by best response to therapy. Further prospective studies are warranted to explore this treatment approach. Citation Format: Katherine K. Clifton, Shana N. Thomas, Jingqin Luo, Jing Xi, Nusayba A. Bagegni, Foluso O. Ademuyiwa, Rama Suresh, Ashley Frith, Andrew A. Davis, Ron Bose, Katherine Weilbaecher, Whitney L. Hensing, Timothy Pluard, Massimo Cristofanilli, Hyo S. Han, Adam M. Brufsky, Kevin Kalinsky, Shom Goel, Seth A. Wander, Lindsay L. Peterson, Cynthia Ma. PD13-09 Clinical outcomes of patients with HR+ HER2- advanced breast cancer with early progression on CDK4/6 inhibitors [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD13-09.

Purpose: Clinical biomarkers to identify patients unlikely to benefit from CDK4/6 inhibition (CDK4/6i) in combination with endocrine therapy (ET) are lacking. We implemented a comprehensive circulating tumor DNA (ctDNA) analysis to identify genomic features for predicting and monitoring treatment resistance. Experimental Design: ctDNA was isolated from 216 plasma samples collected from 51 patients with hormone receptor–positive (HR+)/HER2-negative (HER2−) metastatic breast cancer (MBC) on a phase II trial of palbociclib combined with letrozole or fulvestrant (NCT03007979). Boosted whole-exome sequencing (WES) was performed at baseline and clinical progression to evaluate genomic alterations, mutational signatures, and blood tumor mutational burden (bTMB). Low-pass whole-genome sequencing was performed at baseline and serial timepoints to assess blood copy-number burden (bCNB). Results: High bTMB and bCNB were associated with lack of clinical benefit and significantly shorter progression-free survival (PFS) compared with patients with low bTMB or low bCNB (all P < 0.05). Dominant APOBEC signatures were detected at baseline exclusively in cases with high bTMB (5/13, 38.5%) versus low bTMB (0/37, 0%; P = 0.0006). Alterations in ESR1 were enriched in samples with high bTMB (P = 0.0005). There was a high correlation between bTMB determined by WES and bTMB determined using a 600-gene panel (R = 0.98). During serial monitoring, an increase in bCNB score preceded radiographic progression in 12 of 18 (66.7%) patients. Conclusions: Genomic complexity detected by noninvasive profiling of bTMB and bCNB predicted poor outcomes in patients treated with ET and CDK4/6i and identified early disease progression before imaging. Novel treatment strategies including immunotherapy-based combinations should be investigated in this population.

Purpose:Clinical biomarkers to identify patients unlikely to benefit from CDK4/6 inhibition (CDK4/6i) in combination with endocrine therapy (ET) are lacking. We implemented a comprehensive circulating tumor DNA (ctDNA) analysis to identify genomic features for predicting and monitoring treatment resistance.Experimental Design:ctDNA was isolated from 216 plasma samples collected from 51 patients with hormone receptor–positive (HR+)/HER2-negative (HER2−) metastatic breast cancer (MBC) on a phase II trial of palbociclib combined with letrozole or fulvestrant (NCT03007979). Boosted whole-exome sequencing (WES) was performed at baseline and clinical progression to evaluate genomic alterations, mutational signatures, and blood tumor mutational burden (bTMB). Low-pass whole-genome sequencing was performed at baseline and serial timepoints to assess blood copy-number burden (bCNB).Results:High bTMB and bCNB were associated with lack of clinical benefit and significantly shorter progression-free survival (PFS) compared with patients with low bTMB or low bCNB (all P < 0.05). Dominant APOBEC signatures were detected at baseline exclusively in cases with high bTMB (5/13, 38.5%) versus low bTMB (0/37, 0%; P = 0.0006). Alterations in ESR1 were enriched in samples with high bTMB (P = 0.0005). There was a high correlation between bTMB determined by WES and bTMB determined using a 600-gene panel (R = 0.98). During serial monitoring, an increase in bCNB score preceded radiographic progression in 12 of 18 (66.7%) patients.Conclusions:Genomic complexity detected by noninvasive profiling of bTMB and bCNB predicted poor outcomes in patients treated with ET and CDK4/6i and identified early disease progression before imaging. Novel treatment strategies including immunotherapy-based combinations should be investigated in this population.

Gene alterations associated with shorter PFS.

Supplementary Methods

PredicineATLAS gene panel.

DNA sequencing data summary.

Patient demographics.

Supplementary Figure S1. High bTMB is associated with the presence of specific mutations. Supplementary Figure S2. ROC analysis to determine optimal bTMB cutoff. Supplementary Figure S3. High correlation between bTMB determined from WES and a 152- gene targeted sequencing panel. Supplementary Figure S4. Association between high cfDNA yield and shorter PFS. Supplementary Figure S5. High baseline tumor fraction is associated with shorter PFS. Supplementary Figure S6. bTMB scores are not associated with sites of metastatic spread. Supplementary Figure S7. Specific oncogenic signaling pathways are more frequently altered in patients with high bTMB and bCNB scores. Supplementary Figure S8. Genomic landscape of all patients at baseline. Supplementary Figure S9. bTMB and bCNB at baseline vs. progression. Supplementary Figure S10. Correlation between baseline bCNB and bTMB. Supplementary Figure S11. Comparison of ctDNA dynamics as measured by ctDNA fraction and bCNB during treatment and progression. Supplementary Figure S12. Genome-wide plots of copy number changes across treatment time points. Supplementary Figure S13. Copy number changes detected for RB1 and BRCA2 genes across treatment time points. Supplementary Figure S14. Relationship between ctDNA fraction and bTMB and bCNB Supplementary Figure S15. Relationship between tumor fraction and bCNB.

Background Patients (pts) with ER+ HER2+ breast cancer (BC) are less likely to achieve pathological complete response (pCR) after neoadjuvant chemotherapy with dual HER2 blockade than pts with ER- HER2+ BC. Endocrine therapy (ET) plus trastuzumab is effective in advanced ER+ HER2+ BC, but pCR rate is low in the neoadjuvant setting. Inhibition of CDK4/6 and HER2 results in synergistic reduction in cell proliferation in preclinical studies. We therefore combined ET with CDK4/6 inhibition and trastuzumab in ER+ HER2+ BC as a chemotherapy-sparing regimen. Methods We evaluated the efficacy of palbociclib, letrozole, trastuzumab (PLT) in the neoadjuvant setting for pts with stages II or III ER+ HER2+ BC. Primary endpoint was pCR after 16 weeks of therapy. We assumed null of 15% pCR and pCR ≥ 30% warrants further investigation. To achieve 80% power at 1-sided 0.05 significance, 48 pts were to be enrolled. Evaluable population included pts who completed Cycle (C) 1 unless discontinued due to treatment-emergent adverse events (TEAEs) prior to completing C1. All who received one dose on study were considered evaluable for toxicity. Biopsies were collected at baseline (BL), C1 day 15 (C1D15), and surgery for RNA sequencing and central Ki67 assessment, for PAM50 subtype distribution, complete cell cycle arrest (CCCA: Ki67 ≤2.7%) at C1D15 and surgery, and treatment induced signaling changes. Results Accrual stopped early due to futility. 26 pts accrued were evaluable for efficacy and toxicity. pCR (residual cancer burden- [RCB] 0) was 7.7% (95% CI 0.9 - 25.1%) and RCB 0/I was 38.5% (95% CI 20.2 - 59.4%). TEAEs (n= 337) were seen in all pts (71.5% grade [G] 1, 19.3% G2, 8.6% G3, 0.6% G4); the most common were leukopenia (7.7%), neutropenia (7.1%), anemia (5.9%). G3/4 TEAEs occurred in 19 pts (73.1%). Among the 19, incidence of G3/4 neutropenia was 50%, hypertension 26.9%, leucopenia 7.7%. TEAEs (hypertension, ventricular tachycardia, pulmonary edema) leading to treatment discontinuation were reported in 1 pt. Two pts had at least one SAE. No treatment-related deaths occurred. Pt reported outcomes using NCI PRO-CTCAE revealed no differences in appetite, nausea, respiratory symptoms, edema, palpitations, rashes and dry skin, or concentration from BL to end of C4. Pts had worsening hair loss from BL to end of C4. Ki67 analysis indicated CCCA in 78% at C1D15, compared to 18% at surgery after only P had been discontinued approximately 4 weeks prior to surgery. RNA sequencing was performed on available biopsies collected at BL (N=16), C1D15 (N=5), and surgery (N=2) from 16 pts. Among 16 BL samples, PAM50 subtyping identified 5 (31.3%) basal-like, 2 (12.5%) HER2-E, 6 (37.5%) Lum B, and 3 (18.8%) normal. Subtype switching to Lum A at C1D15 (N=3, 1 each with HER2-E, Lum B, and normal at BL) or normal (N=2, 1 basal and 1 HER2-E at BL) was observed. 161 genes were differentially expressed (FDR p Citation Format: Foluso O Ademuyiwa, Donald Northfelt, Tracey O'Connor, Ellis Levine, Jingqin Luo, Yu Tao, Jeremy Hoog, Marie Laury, Tracy Summa, Trish Hammerschmidt, Zhanfang Guo, Ashley Frith, Katherine Weilbaecher, Mateusz Opyrchal, Rebecca Aft, Katherine Clifton, Rama Suresh, Nusayba Bagegni, Ian S Hagemann, Cynthia X Ma. Phase 2 study of neoadjuvant palbociclib, letrozole, and trastuzumab in patients with ER+ HER2+ breast cancer (PALTAN) [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 P2-13-01.

Background: CDK4/6i combined with ET improves survival for pts with HR+, HER2- MBC. However, biomarkers to predict efficacy and resistance are needed. We hypothesized that a comprehensive next-generation sequencing (NGS)-based liquid biopsy assessment of ctDNA mutation and copy number analysis may identify novel prognostic and predictive biomarkers. Methods: We collected serial blood for ctDNA testing from the 51 pts with HR+, HER2- MBC enrolled in the Alt Dose Palbo trial (NCT03007979), a single-arm phase II study of palbociclib plus letrozole or fulvestrant at 5 days on/2 days off weekly schedule as the first- or second-line ET. The median follow up was 38.2 months at data cutoff for this analysis. Plasma collected at baseline (BL) from all 51 pts, at progression (PD) from all 20 pts who have progressed, and at additional interim timepoints from 2 pts to explore longitutinal changes, with paired germline DNA, were subjected to the PredicineWES+ assay and low-pass whole-genome sequencing (lpWGS). The PredicineWES+ assay provides deep sequencing of 600 genes in the PredicineATLAS panel combined with whole-exome sequencing (WES) of all exonic regions of 20,000 genes enabling genome-wide detection of somatic single nucleotide variation (SNV), indels, copy number variation (CNV) and determination of bTMB. LpWGS offers an unbiased and high-throughput assessment of CNVs and tumor fraction in cell free DNA to derive bCNB. Statistical associations of bTMB, bCNB, and individual alterations with clinical benefit (CB), defined as no PD at 24 weeks by RECIST 1.1, and progression-free survival (PFS) were examined by Fisher’s exact test, Kaplan-Meier analysis, and Cox model. P values were adjusted to control false discovery rate (FDR). Results: The BL median bTMB was 1.6 mutations per megabase pair [IQR 0.6-3.5]. Pts with CB (N=41, 80%) had significantly lower bTMB scores (median [IQR] 1.2 [0.6-2.6] vs. 8.3 [2.4-21.4], (P Citation Format: Andrew Davis, Jingqin Luo, Tiantian Zheng, Lu Tan, Amy Wang, Rama Suresh, Foluso Ademuyiwa, Caron Rigden, Timothy Rearden, Katherine Clifton, Katherine Weilbaecher, Ashley Frith, Pavan K Tandra, Tracy Summa, Brittney Haas, Shana Thomas, Leonel Hernandez-Aya, Lindsay Peterson, Shujun Luo, Bonnie L King, Shidong Jia, Jianjun Yu, Pan Du, Jairam Krishnamurthy, Cynthia X Ma, C Dai. Blood tumor mutational burden (bTMB) and blood copy number burden (bCNB) by genome-wide circulating tumor DNA (ctDNA) assessment predict outcome and resistance in hormone-receptor positive (HR+), HER2 negative (HER2-) metastatic breast cancer (MBC) patients (pts) treated with CDK4/6 inhibitor (CDK4/6i) [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 P2-07-01.

Wastewater contamination threatens the shellfish aquaculture industry by posing risks to public health. Multiple indicators of wastewater contamination, including fecal coliforms (fc), male-specific coliphage (MSC), dissolved nutrients, stable isotope ratios, and artificial sweeteners were analyzed to determine possible sources of wastewater to local shellfish farms. Samples were collected at a wastewater treatment plant outfall (WTPO), nonpoint residential, and agricultural areas of a tidal river, and tidal creek inflows adjacent to farms. To capture seasonal variation, we sampled under warm and cold, and wet and dry conditions. Fc ranged −1, NH4+ concentrations ranged up to 9.58 μM, and δ15N ranged 1.4–7.8‰ across all sites and time periods. Fc and NH4+ were higher, and δ15N was lower in the cold wet period and near residential and agricultural areas. Acesulfame and sucralose concentrations ranged 0.004–0.05 μg L−1 and up to > 0.8 μg L−1, respectively, and did not correlate with other indicators but tended to be higher in residential areas and at the WTPO, supporting their value in differentiating human sewage from other sources. Shoreline disturbance during septic system upgrades may have inadvertently contributed bacterial indicators to shellfish farms. Overall, indicator source dominance depended on environmental conditions, with WTPO and residential sources conveying human-specific indicators to farms year-round, while agricultural and industrial sites contributed additional fc during cold wet periods. The use of multiple indicators will aid managers to detect and define wastewater sources, identify targets for monitoring or remediation, and manage shellfish areas in estuaries with a mosaic of land-derived wastewater sources.

PURPOSE: Patients with triple negative breast cancer (TNBC) who do not achieve pathological complete response (pCR) following neoadjuvant chemotherapy have a high risk of recurrence and death. Molecular characterization may identify patients unlikely to achieve pCR. This neoadjuvant trial was conducted to determine the pCR rate with docetaxel and carboplatin, and to identify molecular alterations and/or immune gene signatures predicting pCR. EXPERIMENTAL DESIGN: Patients with clinical stages II/III TNBC received 6 cycles of docetaxel and carboplatin. The primary objective was to determine if neoadjuvant docetaxel and carboplatin would increase the pCR rate in TNBC compared to historical expectations. We performed whole exome sequencing (WES) and immune profiling on pre-treatment tumor samples to identify alterations that may predict pCR. Thirteen matching on-treatment samples were also analyzed to assess changes in molecular profiles. RESULTS: Fifty-eight of 127 (45.7%) patients achieved pCR. There was a non-significant trend towards higher mutation burden for patients with residual cancer burden (RCB) 0/I versus RCB II/III (median 80, versus 68 variants, p 0.88). TP53 was the most frequently mutated gene, observed in 85.7% of tumors. EGFR, RB1, RAD51AP2, SDK2, L1CAM, KPRP, PCDHA1, CACNA1S, CFAP58, COL22A1, and COL4A5 mutations were observed almost exclusively in pre-treatment samples from patients who achieved pCR. Seven mutations in PCDHA1 were observed in pre-treatment samples from patients who did not achieve pCR. Several immune gene signatures including IDO1, PD-L1, interferon gamma signaling, CTLA4, cytotoxicity, tumor inflammation signature, inflammatory chemokines, cytotoxic cells, lymphoid, PD-L2, exhausted CD8, Tregs, and immunoproteosome were upregulated in pre-treatment samples from patients who achieved pCR. CONCLUSIONS: Neoadjuvant docetaxel and carboplatin resulted in a pCR of 45.7%. WES and immune profiling differentiated patients with and without pCR. TRIAL REGISTRATION: Clinical trial information: NCT02124902, Registered 24 April 2014, & NCT02547987, Registered 10 September 2015.

Purpose: To report the interim analysis of the phase II single-arm noninferiority trial, testing the upfront use of dexrazoxane with doxorubicin on progression-free survival (PFS) and cardiac function in soft-tissue sarcoma (STS). Patients and Methods: Patients with metastatic or unresectable STS who were candidates for first-line treatment with doxorubicin were deemed eligible. An interim analysis was initiated after 33 of 65 patients were enrolled. Using the historical control of 4.6 months PFS for doxorubicin in the front-line setting, we tested whether the addition of dexrazoxane affected the efficacy of doxorubicin in STS. The study was powered so that a decrease of PFS to 3.7 months would be considered noninferior. Secondary aims included cardiac-related mortality, incidence of heart failure/cardiomyopathy, and expansion of cardiac monitoring parameters including three-dimensional echocardiography. Patients were allowed to continue on doxorubicin beyond 600 mg/m2 if they were deriving benefit and were not demonstrating evidence of symptomatic cardiac dysfunction. Results: At interim analysis, upfront use of dexrazoxane with doxorubicin demonstrated a PFS of 8.4 months (95% confidence interval: 5.1–11.2 months). Only 3 patients were removed from study for cardiotoxicity, all on > 600 mg/m2 doxorubicin. No patients required cardiac hospitalization or had new, persistent cardiac dysfunction with left ventricular ejection fraction remaining below 50%. The median administered doxorubicin dose was 450 mg/m2 (interquartile range, 300–750 mg/m2). Conclusions: At interim analysis, dexrazoxane did not reduce PFS in patients with STS treated with doxorubicin. Involvement of cardio-oncologists is beneficial for the monitoring and safe use of high-dose anthracyclines in STS. See related commentary by Benjamin and Minotti, p. 3809

Background: Cyclin-dependent kinases 4 and 6 inhibitors (CDK4/6i) are now standard of care (SOC) for pts with HR+/HER2- MBC. However, aside from HR positivity, there are no biomarkers for pt selection. Although mutations (muts) in genes such as RB1, FAT1, or FGFR, are associated with CDK4/6i resistance, they are rare events in HR+/HER2- MBC. The goal of this study is to examine the ctDNA mut profile, and the impact of commonly mutated genes (ESR1, TP53 and PIK3CA) on progression free survival (PFS) in pts received pal as SOC in a real world experience. Methods: Chart review was performed for pts with HR+/HER2- MBC who received pal and ctDNA Guardant360® (G360) testing between 01/2015 and 06/2020 at Siteman Cancer Center. The Kaplan-Meier method was used to generate time-to-event curves with calculated mPFS. A stratified log-rank test was used for all comparisons with P-values reported. Hazard ratios (HRs) and associated 95% confidence intervals (CI) were calculated with a stratified Cox proportional-hazards model. Results: Among the 73 pts identified, median age was 61.5 years (range 33.7-83.3). 15 (20.5%) pts received pal as 1st-line, 22 (30.1%) pts as 2nd-line, and 36 (49.3%) pts as 3rd-line and beyond. All 73 pts had muts by G360. Top 3 mutated genes are PIK3CA (n=25, 34.2%), TP53 (n=20, 27.4%) and ESR1 (n=17, 23.3%), followed by GATA3 (n=12, 16.4%) and MYC (n=6, 8.2%). For association analysis with PFS, 17 pts were excluded from further analysis due to having had multiple interim therapies between G360 testing and pal therapy, leaving 56 pts who had G360 immediately prior to pal (n=11), during pal (n=13), at progressive disease (PD) on pal (n=20), or had 1 additional therapy after PD on pal (n=12). Among the 56 pts, the median age on pal was 62.8 years (36.6-78.4). Median duration on pal was 7.7 months (mo). Pal was received as 1st-line in 14 (25.0%), 2nd-line in 17 (30.4%) and 3rd-line plus in 25 (44.6%) pts. Muts in PIK3CA, TP53 and ESR1, were identified in 18 (32.1%), 16 (28.6%), and 13 (23.2%) pts, respectively, with rates similar to the entire 73-pt cohort. Among 13 ESR1 mutant pts, 7 had letrozole and 6 had fulvestrant as pal’s endocrine partner. Concurrent muts in 2 of 3 genes were observed in 11 (19.6%) pts (6 with PIK3CA and TP53, and 5 with ESR1 and TP53). The mPFS was 7.4 and 12.6 mo (p=0.03) in pts with or without PIK3CA mut, 7.9 and 12.8 mo (p=0.85) with or without ESR1 mut, and 16.0 and 13.3 mo (p=0.46), with or without TP53 mut, respectively. mPFS for pts with concurrent muts in 2 of the 3 genes was 7.4 mo, compared to 11.7 mo and 13.3 mo in pts with 1 or no mut in these 3 genes (p=0.46). In multivariate analysis that included age, visceral mets and line of therapy, the HRs for PFS were 10 muts, respectively. Conclusions: In this retrospective real world experience, ctDNA muts in PIK3CA and ESR1 as well as higher number of muts in ctDNA were associated with worse outcome in pts received pal. Although several studies have shown CDK4/6i benefit regardless of PIK3CA or ESR1 mut status, our data indicates that muts in these genes render worse prognosis on CDK4/6i and supports PIK3CA and ESR1 muts as driver events in HR+ MBC. PI3Ki or novel ER targeted agents are combined with CDK4/6i in clinical trials and results are eagerly awaited. In addition, further study for pts with higher ctDNA mut number is warranted. Multivariate Cox Proportional Hazards Regression Model on PFSVariablesPFSHR (95% CI)P-valueESR1 (non-mut vs. mut)0.64 (0.26-1.56)0.32TP53 (non-mut vs. mut)1.70 (0.80-3.60)0.16PIK3CA (non-mut vs. mut)0.42 (0.17-1.02)0.06Age (=65 yo)0.92 (0.45-1.87)0.81No. Lines of pal (1st- vs. 3rd-line)0.61 (0.25-1.48)0.28No. Lines of pal (2nd- vs. 3rd-line)0.46 (0.20-1.04)0.06No. of muts (1-5 vs. >10)0.74 (0.24-2.33)0.61No. of muts (6-10 vs. >10)0.64 (0.20-2.07)0.46Visceral mets (no vs. yes)1.25 (0.52-2.98)0.61 Citation Format: Jing Xi, Nusayba Bagegni, Foluso Ademuyiwa, Ashley Frith, Rama Suresh, Anna Roshal, Caron Rigden, Leonel Hernandez-Aya, Lindsay Peterson, Mateusz Opyrchal, Katherine Clifton, Katherine Weilbaecher, Ron Bose, Cynthia Ma. Circulating tumor DNA (ctDNA) mutation (mut) profile in relation to paboclicib (pal) efficacy in hormone receptor positive (HR+) and HER2 negative (HER2-) metastatic breast cancer (MBC) [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 PS2-18.

Background: With advances in next generation sequencing (NGS) and now approved targeted therapy in breast cancer, genomic testing to identify potentially actionable mutations has become a common practice in patients (pts) with advanced breast cancer using both ctDNA and traditional tissue-based assays. Less is known regarding physician practice patterns in obtaining NGS testing and the practical implications of testing in older adults with breast cancer.Methods: Pts with advanced breast cancer underwent molecular profiling using a plasma-based ctDNA NGS assay (Guardant360® or Tempus®) between 5/2015 and 5/2020 at Siteman Cancer Center. Pts with advanced breast cancer who underwent genomic profiling using a tissue-based NGS assay (Tempus®) between 12/2017 and 5/2020 at this institution were also included. Clinicopathological histories were obtained from the medical record. Correlations were examined using a Fisher’s exact test.Results: During 5/15-5/20, 244 pts underwent ctDNA testing and 147 pts had a tissue-based NGS assay performed. There was no significant difference between the number of pts ≥ 65 years-old who underwent ctDNA testing (n=78, 32.0%) and tissue testing (n=37, 25.2%). There was no statistically significant difference between date of metastatic diagnosis and date of NGS testing between the older and younger cohorts. In pts who underwent tissue-based NGS testing, there was no significant difference between site of tissue tested (distant recurrence vs local) in the older and younger cohorts. The most common clinical managements following both ctDNA and tissue-based testing are presented in Table 1. Out of the 391 pts who underwent testing, 27 pts had both ctDNA and tissue-based NGS performed. Pts ≥ 65 were less likely to have both assays performed (n=3, 11.1%; p Conclusion: Older adults, who are typically less likely to be included in clinical trials, may still benefit from NGS to reveal potentially targetable mutations. It is reassuring in our cohort that older adults had ctDNA and tissue-based NGS performed at similar rates as part of standard of care treatment. The clinical management following NGS testing was also not significantly different in the older adult cohort. Older adults were less likely to have both tissue and ctDNA testing performed however, given the high concordance rates between tests, this may be less clinically relevant. Table 1clinical management following NGS testing≥65 years-old Citation Format: Katherine K Clifton, Jingqin Luo, Yu Tao, Jennifer Saam, Thereasa Rich, Timothy Rearden, Anna Roshal, Ashley Frith, Caron Rigden, Foluso Ademuyiwa, Katherine Weilbaecher, Leonel Hernandez Aya, Lindsay Peterson, Nusayba Bagegni, Rama Suresh, Ron Bose, Tanya Wildes, Mateusz Opyrchal, Cynthia Ma. Next generation sequencing (NGS) in older adults with breast cancer using tissue-based and circulating tumor DNA (ctDNA) assays [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 PS2-09.

1089 Background: Although the noninvasive nature of ctDNA testing is attractive in an older adult population, less is known regarding the mutation profiles of ctDNA in the older adult breast cancer population as this population is often excluded from studies. Previous tissue testing has shown differences in mutation profiles between older and younger adults with breast cancer. The objective of this study is to assess differences in mutation profiles in the older and younger adult breast cancer population using a ctDNA assay. Methods: Patients (pts) with advanced breast cancer underwent molecular profiling using a plasma-based ctDNA NGS assay (Guardant360) between 5/2015-10/2019 at Siteman Cancer Center. Clinicopathological histories were obtained from the medical record. The results of a multicenter database of pts with advanced breast cancer who had undergone molecular profiling using Guardant360 were obtained. Associations between mutations and age were measured using a Fisher’s exact test. Results: In the single institution cohort, of the 214 patients who underwent testing, 148 (69.16%) were < 65 and 66 (30.84%) ≥ 65 years-old. The most frequently mutated genes in age < 65 pts were TP53 (48.65%), PIK3CA (35.81%), and ESR1 (30.41%) while the most frequently mutated genes in age≥65 pts were PIK3CA (56.06%), TP53 (51.52%), ESR1 (25.76%), and ATM (21.21%). ATM, BRAF and PIK3CA mutations were found more frequently in age≥ 65 pts with ER+ HER2- breast tumors (p < 0.01). MYC and ESR1 mutations were not significantly associated with age, overall or within subtype. Overall ctDNA resulted in change in management in 19.8% pts (40/202). In the larger multicenter cohort, of the 8803 pts who underwent testing, 5367 (61.0%) were < 65 and 3417 (38.8%) ≥ 65 years-old. ATM, ESR1 and PIK3CA mutations were more common in age≥65 pts (p < 0.0001) and MYC mutations were less common in age≥65 pts (p < 0.0001). Conclusions: This study found that ctDNA is a feasible, attractive alternative to traditional biopsies and may identify actionable mutations in older adults with breast cancer. When controlling for subtype, results from a single institution were similar to the larger multicenter cohort showing ATM and PIK3CA were more common in the older adult population. This data suggests there may be additional molecular differences between breast cancer in older compared to younger adults that warrants further investigation.

Introduction: Palbo is approved in combination with an aromatase inhibitor or fulvestrant (FUL) for the treatment of HR+ HER2- MBC. The incidence of grade (G) 3/4 neutropenia (ANC) approaching 66% has been observed in phase 3 trials of palbo. We hypothesize that an alternative schedule of palbo, 5 days on/2 days off every 7 days, reduces the severity of neutropenia, therefore allowing continued weekly dosing and less dose reduction and discontinuation. Methods: A single arm phase II study (Alt Dose Palbo) was conducted in patients (pts) with HR+ HER2- MBC who had ≤1 prior systemic therapy in the metastatic setting (NCT03007979). Pts were treated with palbo 125 mg daily on a 5 days on/2 days off every 7-day schedule, along with letrozole (LET) or FUL per treating physician. Goserelin was administered if premenopausal. The primary objective was to determine the rate of G3/4 ANC within the first 29 days of treatment. Secondary objectives included determining the rate of G3/4 ANC during all cycles, rate of palbo dose reduction/interruption/discontinuation, adverse event (AE) profile per CTCAE v5, progression free survival (PFS), objective response rate (ORR) and clinical benefit rate (CBR) by RECIST 1.1. The sample size of 47 was calculated to provide 90% power based on one-sample binomial exact test at a 5% alpha level to test the one-sided null hypothesis of G3/4 ANC rate >62% versus the alternative of Table 1C1 D1-29 AEG1G2G3TotalWBC decreased26%50%17%93%ANC decreased10%43%21%74%Anemia38%12%0%50%Fatigue29%0%0%29%Platelets decreased14%0%2%17%Nausea12%2%0%14%All cycle AEG1G2G3TotalWBC decreased19%50%26%95%ANC decreased5%40%36%81%Anemia50%21%2%74%Fatigue36%5%0%40%Nausea26%2%0%29%Platelets decreased24%0%2%26%Alopecia21%0%0%21%Mucositis19%0%0%19%Hot flashes17%2%0%19%Constipation14%0%0%14%Arthralgia12%2%0%14%AST elevated10%0%2%12%Anorexia12%0%0%12%ALT elevated7%0%5%12% Citation Format: Jairam Krishnamurthy, Jingqin Luo, Foluso Ademuyiwa, Rama Suresh, Caron Rigden, Timothy Reardon, Katherine Weilbaecher, Ashley Frith, Anna Roshal, Pavan Tandra, Mathew Cherian, Tracy Summa, Shana Thomas, Leonel Hernandez-Aya, Lindsay Peterson, Cynthia Ma. A phase II trial assessing the safety of an alternative dosing schedule of palbociclib (palbo) in hormone receptor positive (HR+), HER2 negative (HER2-) metastatic breast cancer (MBC): Alt Dose Palbo [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-19-13.

Background: Anthracycline- and taxane-based neoadjuvant chemotherapy (NAT) in triple negative breast cancer (TNBC) patients yields a pathological complete response (pCR) rate of approximately 45%. Anthracyclines can lead to long-term toxicities including congestive heart failure and leukemia. TNBC patients achieving pCR have excellent long-term outcomes irrespective of NAT regimen. This study was designed to evaluate the efficacy of a non-anthracycline NAT regimen with carboplatin and docetaxel in TNBC. Correlative studies include detecting and tracking plasma circulating tumor DNA (ctDNA) to determine if it will predict clinical outcomes, and whole exome sequencing (WES) on tissue samples to decipher the genomic architecture of those who achieve pCR versus those who do not. Methods: This is a joint analysis of two identical multicenter trials. Eligible patients with AJCC 7 clinical stages II and III TNBC received docetaxel 75mg/m2 and carboplatin AUC 6 every 3 weeks X 6 cycles. Following NAT, all patients underwent definitive surgery. The primary endpoint is pCR (no invasive tumor in the breast and axilla). Secondary objectives include evaluating ctDNA as a prognostic biomarker that may be used in identifying TNBC patients at a high risk of disease relapse, and evaluating differences in the genomic architecture between pCR and non-pCR patients. Patients have a research biopsy at baseline, cycle 1 day 3 (optional), and at definitive surgery for those with residual disease. Plasma for ctDNA is collected at baseline, cycle 1 day 3, at definitive surgery, and every 6 months for 5 years. Results: Between 2014 and 2019, 103 patients have been registered. Median age is 53 years (range 25-74), 27.2%: African-American, 77.7%: clinical stage II. Ninety-nine have completed NAT and have had surgery. In the intent to treat population, the preliminary pCR rate is 46.5% (95% CI 36.9% - 56.2%). Nine (8.7%) have developed recurrent disease, and 7 (6.8%) have died. Preliminary ctDNA results from 6 patients (4 non-pCR, 2 pCR) show that ctDNA is detectable in 67%. We identified 627 somatic variants by exome analysis. Of these, 10 variants overlapped with the Swift panel (Accel-Amplicon™ 56G Oncology Panel v2) used for ctDNA sequencing and variant detection. TP53 variants were identified in all 6 patients’ tumor tissue samples. At least one TP53 variant was identified in 4 patients’ baseline pre-chemotherapy ctDNA. Both pCR patients had either no detectable ctDNA TP53 mutations, or clearance of ctDNA following chemotherapy. Three non-PCR patients had persistent TP53 mutations in ctDNA during the treatment course. WES and ctDNA analysis on all patients is currently ongoing. Conclusions: We report a very encouraging pCR rate of 46.5% in TNBC patients with carboplatin and docetaxel NAT. This rate is similar to observed rates with anthracycline- and taxane-based NAT and may represent an option for treatment for TNBC patients. Correlative genomic and ctDNA studies are ongoing. Clinical trial information: NCT02124902 & NCT02547987. Citation Format: FOLUSO O ADEMUYIWA, Mothaffar F Rimawi, Tracy Summa, Jingqin Luo, Tao Wang, Rama Suresh, Lindsay Peterson, Michael Naughton, Ashley Frith, Leonel Hernandez-Aya, Katherine Weilbaecher, Cynthia Ma, Aadel A Chaudhuri, Yang-Yang Feng, Zachary L Skidmore, Obi L Griffith, Malachi Griffith, Matthew Ellis. Neoadjuvant treatment of triple negative breast cancer patients with docetaxel and carboplatin to assess anti-tumor activity [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-16-03.

Palbociclib 3-weeks-on/1-week-off, combined with hormonal therapy, is approved for hormone receptor positive (HR+)/HER2-negative (HER2−) advanced/metastatic breast cancer (MBC). Neutropenia is the most frequent adverse event (AE). We aim to determine whether an alternative 5-days-on/2-days-off weekly schedule reduces grade 3 and above neutropenia (G3 + ANC) incidence. In this single-arm phase II trial, patients with HR+/HER2− MBC received palbociclib 125 mg, 5-days-on/2-days-off, plus letrozole or fulvestrant per physician, on a 28-day cycle (C), as their first- or second-line treatment. The primary endpoint was G3 + ANC in the first 29 days (C1). Secondary endpoints included AEs, efficacy, and serum thymidine kinase 1 (sTK1) activity. At data-cutoff, fifty-four patients received a median of 13 cycles (range 2.6–43.5). The rate of G3 + ANC was 21.3% (95% CI: 11.2–36.1%) without G4 in C1, and 40.7% (95% CI: 27.9–54.9%), including 38.9% G3 and 1.8% G4, in all cycles. The clinical benefit rate was 80.4% (95% CI: 66.5–89.7%). The median progression-free survival (mPFS) (95% CI) was 19.75 (12.11–34.89), 33.5 (17.25–not reached [NR]), and 11.96 (10.43–NR) months, in the overall, endocrine sensitive or resistant population, respectively. High sTK1 at baseline, C1 day 15 (C1D15), and C2D1 were independently prognostic for shorter PFS (p = 9.91 × 10−4, 0.001, 0.007, respectively). sTK1 decreased on C1D15 (p = 4.03 × 10−7), indicating target inhibition. Rise in sTK1 predicted progression, with the median lead time of 59.5 (inter-quartile range: −206.25–0) days. Palbociclib, 5-days-on/2-days-off weekly, met its primary endpoint with reduced G3 + ANC, without compromising efficacy. sTK1 is prognostic and shows promise in monitoring the palbociclib response. ClinicalTrials.gov#: NCT3007979.

Half of hormone receptor-positive (HR+) breast cancer patients will develop joint pain, termed aromatase inhibitor-induced arthralgia (AIA), while taking aromatase inhibitor therapy. Though there is no universally accepted effective treatment for AIA, there has been some evidence to support high-dose vitamin D as a treatment. We randomized post-menopausal women who were beginning adjuvant AI therapy to receive standard-dose vitamin D3 (800 IU daily for 52 weeks), or high-dose vitamin D3 (50,000 IU weekly for 12 weeks, followed by 2000 IU daily for 40 weeks). The primary end point was development of AIA. The trial was designed to enroll 184 patients. This futility analysis was performed after 93 patients were enrolled. The high-dose vitamin D regimen was effective in raising serum vitamin D levels, but there was no significant difference in development of AIA between the two arms. In the high-dose arm, 25 patients (54%) developed AIA, compared to 27 patients (57%) in the standard-dose arm. The planned futility analysis was positive; thus, the study was terminated. Neither baseline vitamin D nor 12-week vitamin D level was predictive of AIA development. Although vitamin D levels were increased in the high-dose arm, there was no significant signal for benefit of high-dose vitamin D supplementation for AIA prevention in this unblinded trial. This study, along with several others, implies that vitamin D likely does not play a significant role in AIA for the majority of patients.

Background: Platinum-based chemotherapy is still considered investigational for the treatment of sporadic triple negative breast cancer (TNBC). Since patients with TNBC have a high rate of chemotherapy resistance, it is critical to identify platinum-sensitive individuals prior to initiating therapy. Higher absolute lymphocyte count (ALC) is associated with improved clinical response to anthracycline-based chemotherapy, the current standard of care in TNBC. We report the initial results of a phase II single arm study evaluating the efficacy of neoadjuvant carboplatin and docetaxel in TNBC. We also report results of an exploratory analysis assessing whether ALC can be used to predict pathologic complete response (pCR) after treatment with platinum-based chemotherapy. Patients and Methods: 78 patients with clinical stage II or III TNBC have been enrolled in this ongoing study evaluating the efficacy of neoadjuvant carboplatin and docetaxel (NCT201404107). Patients received docetaxel 75 mg/m2 and carboplatin AUC 6 every three weeks for a total of 6 cycles. Blood samples were collected prior to each cycle, and a posttreatment sample was collected > 3 weeks after completing cycle 6. pCR was defined as no residual invasive disease in the breast, with or without ductal carcinoma in situ, and no tumor deposits in sampled lymph nodes. Baseline characteristics of patients were summarized with descriptive statistics. Univariate and multivariate logistic regression analyses were used to identify factors associated with pCR. Results: Out of the 78 enrolled patients, 60 have completed all 6 treatment cycles and surgery. The preliminary pCR rate is 46.7%. Age, race, clinical stage, and tumor grade determined at time of diagnosis were not significantly different between pCR patients and non-pCR patients. In univariate analyses, patients with higher ALCs at the posttreatment time point were more likely to have pCR than those who had lower ALCs (OR 5.5, 95% CI 1.5-20.7, p=0.011). Additionally, patients who had higher minimum ALCs were also more likely to have pCR (OR 9.1, 95% CI 1.5-54.9, p=0.016). Baseline ALC values were not associated with pCR. The associations of posttreatment and minimum ALCs to pCR remained statistically significant even after controlling for age and clinical stage at time of diagnosis (posttreatment ALC OR 7.6, 95% CI 1.7-34.8, p=0.009; minimum ALC OR 9.0, 95% CI 1.5-55.2, p=0.018). Conclusion: The pCR rate of our cohort is similar to that of other trials evaluating neoadjuvant platinum-based chemotherapy in TNBC. Baseline ALC did not predict which patients would achieve pCR. However, the associations of posttreatment and minimum ALCs with pCR indicate patients who are able to maintain a robust population of circulating lymphocytes throughout treatment with platinum-based chemotherapy are more likely to respond favorably. The link between patient immunity and platinum-based chemotherapy suggests addition of immunotherapy agents to neoadjuvant chemotherapy may improve patient outcomes. Citation Format: Chen I, Guo F, Summa T, Luo J, Ellis MJ, Ma CX, Weilbaecher KN, Naughton MJ, Suresh R, Peterson LL, Cherian MA, Bose R, Frith AE, Hernandez-Aya LF, Gillanders WE, Ademuyiwa FO. Is absolute lymphocyte count associated with platinum-sensitivity? A phase II single arm study evaluating the efficacy of neoadjuvant carboplatin and docetaxel in triple 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 P1-15-05.

Purpose: Patients with triple negative breast cancer (TNBC) who do not achieve pathological complete response (pCR) following neoadjuvant chemotherapy have a high risk of recurrence and death. Molecular characterization may identify patients unlikely to achieve pCR. This neoadjuvant trial was conducted to determine the pCR rate with docetaxel and carboplatin, and to identify molecular alterations and/or immune gene signatures predicting pCR.Experimental Design: Patients with clinical stages II/III TNBC received 6 cycles of docetaxel and carboplatin. The primary objective was to determine if neoadjuvant docetaxel and carboplatin would increase the pCR rate in TNBC compared to historical expectations. We performed whole exome sequencing (WES) and immune profiling on pre-treatment tumor samples to identify alterations that may predict pCR. Thirteen matching on-treatment samples were also analyzed to assess changes in molecular profiles.Results: Fifty-eight of 127 (45.7%) patients achieved pCR. There was a non-significant trend towards higher mutation burden for patients with residual cancer burden (RCB) 0/I versus RCB II/III (median 80, versus 68 variants, p 0.88). TP53 was the most frequently mutated gene, observed in 85.7% of tumors. EGFR, RB1, RAD51AP2, SDK2, L1CAM, KPRP, PCDHA1, CACNA1S, CFAP58, COL22A1, and COL4A5 mutations were observed almost exclusively in pre-treatment samples from patients who achieved pCR. Seven mutations in PCDHA1 were observed in pre-treatment samples from patients who did not achieve pCR. Several immune gene signatures including IDO1, PD-L1, interferon gamma signaling, CTLA4, cytotoxicity, tumor inflammation signature, inflammatory chemokines, cytotoxic cells, lymphoid, PD-L2, exhausted CD8, Tregs, and immunoproteosome were upregulated in pre-treatment samples from patients who achieved pCR.Conclusions: Neoadjuvant docetaxel and carboplatin resulted in a pCR of 45.7%. WES and immune profiling differentiated patients with and without pCR. Trial registration: Clinical trial information: NCT02124902, Registered 24 April 2014, & NCT02547987, Registered 10 September 2015.

The purpose of the study was to assess the utility of tumor biomarkers, ultrasound (US) and US-guided diffuse optical tomography (DOT) in early prediction of breast cancer response to neoadjuvant therapy (NAT). This prospective HIPAA compliant study was approved by the institutional review board. Forty one patients were imaged with US and US-guided DOT prior to NAT, at completion of the first three treatment cycles, and prior to definitive surgery from February 2017 to January 2020. Miller-Payne grading was used to assess pathologic response. Receiver operating characteristic curves (ROCs) were derived from logistic regression using independent variables, including: tumor biomarkers, US maximum diameter, percentage reduction of the diameter (%US), pretreatment maximum total hemoglobin concentration (HbT) and percentage reduction in HbT (%HbT) at different treatment time points. Resulting ROCs were compared using area under the curve (AUC). Statistical significance was tested using two-sided two-sample student t-test with P

Background The cyclin-dependent kinase (CDK) 4/6 inhibitor Pal is approved for HR+ HER2- MBC. However, the optimal therapy following Pal progression is unknown. Therefore we conducted this retrospective study to review Pal efficacy and summarize the practice pattern and responses to subsequent treatments post Pal progression. Methods We performed a chart review of pts with HR+ HER2- MBC who began Pal treatment at Washington University Siteman Cancer Center between Feb 16, 2015 and July 13, 2016 and collected information on pts demographics, diagnosis, and treatment history. Duration of therapy was used to calculate the progression free survival (PFS) for each regimen. Treatment was considered first-line if administered without any prior systemic therapy or at least 1 year from completion of adjuvant hormonal therapy (HT). Treatments received after progression on 1st line therapy or upon relapse during or within 1 year from the completion of adjuvant HT were considered second-line regimens. Statistical analyses were performed on SAS software, version 9.4. The Kaplan-Meier method was used to generate time-to-event curves, from which median PFS was calculated. A stratified log-rank test was used for all comparisons, and the P value derived from the comparison was reported. Results We completed a chart review for 81 pts (78 female and 3 male; 63 Caucasian, 14 African American, and 4 other races) with HR+ HER2- MBC (68 were ER+PR+, 13 were ER+PR-) who received Pal plus letrozole (n=65) or fulvestrant (n=15) or anastrozole (n=1), with a median age of 62.0 years (range 28.1 - 85.6) at the start of Pal. The median follow up was 20.0 months (mos) (range 10.8 – 27.9). 25 pts were still on Pal treatment. The median PFS on Pal was 19.9 mos in the first-line setting (n=20), compared to 12.1 mos and 4.4 mos in the second-line (n=14) and subsequent lines (n=47), respectively (p=0.0287). Among the 54 pts who progressed on Pal, 38 moved on to the next treatment. 20 pts received chemotherapy and 16 pts received HT or a HT combination. 2 pts received fulvestrant plus Pal upon progression on letrozole plus Pal, and treatment was still ongoing at 4 mos and 7 mos of follow up, respectively. The most common treatments post Pal were single-agent capecitabine (Cape) (n=9) and the combination of exemestane (Exe) and everolimus (Eve) (n=8). The median PFS was 4.7 mos with Cape compared to 8.4 mos with Exe and Eve (p=0.60). The median PFS was 4.7 mos for the 20 pts who received chemo, whereas the median PFS was 4.9 mos with subsequent HT (n=16) (p=0.75). Conclusion Pal plus letrozole or fulvestrant is effective for the treatment of HR+ HER2- MBC, with activity observed beyond the 1st and 2nd line treatment settings. The PFS of Pal observed in this single center retrospective study is consistent with that of published data. Single-agent cape or the Exe and Eve combination were common treatment choices following progression on Pal. Although the study is limited by its small sample size, the median PFS of 8.4 mos with Exe and Eve indicates its potential efficacy in the setting of Pal progression. Additional pts and followup data will be presented. Citation Format: Xi J, Oza A, Thomas S, Naughton M, Ademuyiwa F, Weilbaecher KN, Suresh R, Bose R, Cherian MA, Hernandez-Aya L, Frith A, Peterson LL, Krishnamurthy J, Ma CX. Retrospective review of palbociclib (Pal) efficacy and benefit from subsequent treatments following Pal progression in patients (pts) with hormone receptor positive (HR+) and HER2 negative (HER2-) metastatic breast cancer (MBC) [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 P5-21-30.

Half of hormone receptor-positive (HR+) breast cancer patients will develop joint pain, termed aromatase inhibitor-induced arthralgia (AIA), while taking aromatase inhibitor therapy. Though there is no universally accepted effective treatment for AIA, there has been some evidence to support high-dose vitamin D as a treatment.We randomized post-menopausal women who were beginning adjuvant AI therapy to receive standard-dose vitamin D3 (800 IU daily for 52 weeks), or high-dose vitamin D3 (50,000 IU weekly for 12 weeks, followed by 2000 IU daily for 40 weeks). The primary end point was development of AIA. The trial was designed to enroll 184 patients. This futility analysis was performed after 93 patients were enrolled.The high-dose vitamin D regimen was effective in raising serum vitamin D levels, but there was no significant difference in development of AIA between the two arms. In the high-dose arm, 25 patients (54%) developed AIA, compared to 27 patients (57%) in the standard-dose arm. The planned futility analysis was positive; thus, the study was terminated. Neither baseline vitamin D nor 12-week vitamin D level was predictive of AIA development.Although vitamin D levels were increased in the high-dose arm, there was no significant signal for benefit of high-dose vitamin D supplementation for AIA prevention in this unblinded trial. This study, along with several others, implies that vitamin D likely does not play a significant role in AIA for the majority of patients.

Background: The approved 3 weeks (wks) on/1 wk off schedule of PAL results in grade (G)3+ neutropenia (ANC) up to 66%. We hypothesized that an alternative schedule (Alt Dose Pal), 5 on/2 off every 7 days, reduces the rate of G3+ ANC, allowing continued weekly dosing. In addition, based on our previous study supporting sTK1, an E2F-dependent enzyme critical for DNA synthesis, as a pharmacodynamic indicator of CDK4/6 inhibition, we hypothesized that Alt Dose Pal inhibits sTK1 and sTK1 dynamics predicts PAL response. Methods: A single arm phase II trial was conducted in HR+ HER2- MBC, ≤1 prior endocrine therapy (ET) for MBC (NCT03007979). Pts received PAL 125 mg daily, 5 on/2 off weekly, plus letrozole (LET) or fulvestrant (FUL) per physician choice, on a 28-day cycle (C). Goserelin was added if premenopausal. Complete blood count and chemistry panel were done at baseline (BL), C1&2D15, and D1 of C2+. The primary objective was to determine the rate of G3+ ANC in C1 D1-D29. Secondary objectives were to assess the rate of all cycle G3+ ANC, PAL dose reduction/discontinuation, adverse events (AE) per CTCAE v5, progression free survival (PFS), objective response rate (ORR: CR+PR (complete and partial responses)) and clinical benefit rate (CBR: no progression (PD) in 24 wks) by RECIST 1.1. The sample size of 47 provides 90% power, 1-sample binomial exact test, 5% alpha, to test the 1-sided null hypothesis of G3+ ANC rate >62% vs the alternative of 10% or G3+. The ORR was 50% (2 CR, 13 PR, 95% CI: 33.15%-66.85%) in 30 pts with measurable disease (n=29) or non-measurable but CR (n=1). The CBR was 81.63% (95% CI: 67.5%-90.76%) in 40 (2CR, 13 PR, 25 SD ≥24 wks) of 49 evaluable pts. The median PFS (mPFS) was 24.3 mo (95% CI 15~not reached (NR)) overall. The mPFS was 33.5 mo (95% CI 17.3~NR) and 12 mo (95% CI: 10.4~NR), in ET sensitive and resistant population, respectively. sTK1 was significantly reduced, 80% down to undetectable, as early as C1D15 (p=7.77E-07). BL sTK1 levels correlated with PD vs non-PD (p=0.003) as best response and negatively correlated with PFS (p=0.002). sTK1 rose significantly at PD (p=0.0003). A median lead time of 80.6 (IQ range 6.8-189.2) days was observed for rising TK before RECIST PD. Conclusion: The Alt Dose Pal trial met its primary endpoint with reduced G3+ ANC. The efficacy data is comparable to prior reports. sTK1 shows promise for PAL response prediction and monitoring. Table 1 AEAEG1G2G3G4TotalC1 D1-29 (n=47)Leukopenia13 (27.6%)22 (46.8%)7 (14.9%)042 (89%)Neutropenia6 (12.8%)18 (38.3%)10 (21.3%)034 (72%)Anemia18 (38.3%)5 (10.6%)0023 (49%)Lymphopenia6 (12.8%)8 (17%)2 (4.3%)016 (34%)Fatigue13 (27.7%)00013 (28%)Hot flashes7 (14.9%)0007 (15%)Nausea6 (12.8%)1 (2.1%)007 (15%)Thrombocytopenia5 (10.6%)1 (2.1%)006 (13%)Alopecia5 (10.6%)0005 (11%)Dizziness1 (2.1%)01 (2.1%)02 (4%)All cycles (n=54)Leukopenia10 (18.5%)22 (40.7%)21 (38.9%)053 (98%)Neutropenia4 (7.4%)21 (38.9%)21 (38.9%)1 (1.9%)47 (87%)Anemia29 (53.7%)12 (22.2%)3 (5.6%)044 (82%)Lymphopenia8 (14.8%)16 (29.6%)10 (18.5%)034 (63%)Fatigue19 (35.2%)4 (7.4%)0023 (43%)Nausea19 (35.2%)3 (5.6%)0022 (41%)Alopecia18 (33.3%)00018 (33%)Thrombocytopenia15 (27.8%)01 (1.9%) *016 (30%)ALT elevated3 (5.6%)02 (3.7%)05 (9%)AST elevated4 (7.4%)01 (1.9%)05 (9%)*pt died from subdural hematoma (G5) Citation Format: Jairam Krishnamurthy, Jingqin Luo, Rama Suresh, Foluso Ademuyiwa, Caron Rigden, Timothy Reardon, Katherine Clifton, Katherine Weilbaecher, Ashley Frith, Anna Roshal, Pavan Tandra, Mathew Cherian, Tracy Summa, Shana Thomas, Leonel Hernandez-Aya, Mattias Bergqvist, Lindsay Peterson, Cynthia X Ma. Safety and efficacy of an alternative schedule of palbociclib (PAL) in hormone receptor positive (HR+), HER2 negative (HER2-) metastatic breast cancer (MBC) and the utility of serum thymidine kinase 1 (sTK1) activity in predicting PAL response [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 PS12-02.

1016 Background: The ph III EMBRACE trial of E vs physician’s choice of tx led to FDA approval of E as ≥3rd-line tx for MBC pts with prior exposure to anthracyclines/taxanes. The ph III BOLD 301 trial of E vs capecitabine in advanced BC treated with anthracyclines/taxanes showed a nonsignificant trend to improved median OS for all pts; pre-planned analysis by HER2 status revealed a nominally significant benefit for HER2- pts. Methods: RU011201I is an investigator initiated ph III trial with 1:1 randomization to E (1.4 mg/m2 D1,8 q21days) vs P (90 mg/m2 D1,8,15 q28days) within strata defined by (neo)adjuvant taxanes (yes/no), HR status (+/-), and line of tx (1st/2nd). Pts had measurable or non-measurable disease by RECIST v1.1; new or progressive mets; peripheral neuropathy (PN) gr3 mos were allowed. (Neo)adjuvant taxanes were allowed if >12 mos between tx completion and disease recurrence. Radiographic studies occur q12wks. Survival data are collected q12wks after the Off-Tx Visit. Pts reported side effects weekly; post-baseline symptomatic AE rates worse than baseline were compared between arms using Fisher’s exact tests. We report clinical outcomes and the primary objective related to PRO-CTCAE use. Results: 201 pts enrolled 3/2014 - 5/2018 with 33.8 mos median f/u; 3 are on tx as of 2/20/20 (1E, 2P). Pt characteristics were the same between E vs P: median age 62 yrs (range 27-85); 42% prior taxane; 78% ER+; 70% starting 1st line tx. Baseline lesion distribution was similar except for lung mets (37E, 53P). No difference was seen between E vs P in PFS (5.7 vs 5.9 mos; P=0.72), OS (18.1 vs 16.4 mos; P=0.75), TTF (5.3 vs 4.9 mos; P=0.82), DOR (10.8 vs 12.3 mos; P=0.84), or number of metastatic events (55 vs 54). 37E and 36P pts required ≥1 dose reduction. Hematologic toxicities ≥ gr 3 were higher with E (40 vs 22%). PN events were similar: 56 vs 58 total, 4 vs 7 motor, 52 vs 51 sensory. Median duration of PN and median time to 1st PN event were 74 vs 140 and 56 vs 41 days. Worsened numbness/tingling severity and other pt-reported AE rates were similar, but worsened numbness/tingling interference (63% vs 78%, P=0.04) and vomiting frequency (35% vs 57%, P=0.005) were lower with E. Conclusions: Clinical outcomes were equivalent with E vs P as 1st/2nd line tx for HER2- advanced BC. The nature and severity of PN were similar between arms, but time of onset, duration, and interference with daily living favor E. E may be a suitable treatment option in this setting. Clinical trial information: NCT02037529 .

Lung cancer is the leading cause of cancer-related mortality and is responsible for more deaths than breast cancer, prostate cancer, and colon cancer combined. The majority of patients diagnosed with lung cancer are over the age of 65. Despite the prevalence of lung cancer in older adults, they have been notoriously underrepresented in clinical trials designed to help guide clinicians in the management of treatment. In the past 15 years, there have been many improvements that collectively have extended the lives of patients with metastatic lung cancer an average of one year after diagnosis. It is now well-established that age does not diminish the benefit of cancer treatment. However, certain toxicities are more common and may be less tolerated in this age group. It is therefore of paramount importance that clinicians work together to tease out which patients will benefit the most from treatment and to minimize toxicity.

Sarcomas collectively represent over 100 different subtypes of bone and soft tissue tumors of mesenchymal origin. The low response rate to cytotoxic chemotherapies has necessitated the need for development of either histologically driven or pathway-specific targeted therapies. As our understanding of the molecular mechanisms driving certain subtypes is rapidly advancing, the number of targeted therapies is also increasing. Recently identified novel druggable targets include the MDM2 amplifications in well-differentiated and dedifferentiated liposarcomas, the new translocation NAB2:STAT6 of solitary fibrous tumors, the angiopoeitin-TIE2 pathway in angiosarcoma, the suppression of Mcl1 in X:18/synovial sarcomas, the mTOR pathway in malignant peripheral nerve sheath tumors, CDK4 in alveolar rhabdomyosarcoma, cMET regulation in alveolar soft parts sarcoma, the metabolic abnormalities in wild-type/SHD GIST, and the lack of argininosuccinate synthetase 1 expression seen in most sarcomas. It is through a fundamental understanding of sarcoma biology that clinical trials based on molecular targets can be developed.