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1523 citation(s) found for "Ma, Rachel".

Sustained minimal residual disease negativity in newly diagnosed multiple myeloma and the impact of daratumumab in MAIA and ALCYONE
Miguel, Jesús F. San , Paiva, Bruno , Kumar, Shaji , Mateos, María‐Victoria , Usmani, Saad Z. , Cook, Gordon , Cavo, Michèle , Quach, Hang , Ukropec, Jon, Ramaswami, Priya, Pei, Huiling , Qi, Mia, Sun, Steven , Wang, Jianping , Krevvata, Maria, DeAngelis, Nikki, Heuck, Christoph, Rampelbergh, Rian Van , Kudva, Anupa, Kobos, Rachel, Qi, Ming , San-Miguel, Jesus , Paiva, Bruno , Kumar, Shaji K , Mateos, María-Victoria , Quach, Hang , Cook, Gordon , Usmani, Saad , Avet‐Loiseau, Hervé , Dimopoulos, Meletios Α. , Facon, Thierry T.F. , Touzeau, Cyrille , Jakubowiak, Andrzej , Bahlis, Nizar Jacques

Blood | July 16, 2021 | Volume: 139 | Issue: 4 | Pages: 492-501

10.1182/blood.2020010439 | PMID 34269818 Get It

Abstract In patients with transplant-ineligible newly diagnosed multiple myeloma (NDMM), daratumumab reduced the risk of disease progression or death by 44% in MAIA (daratumumab/lenalidomide/dexamethasone [D-Rd]) and 58% in ALCYONE (daratumumab/bortezomib/melphalan/prednisone [D-VMP]). Minimal residual disease (MRD) is a sensitive measure of disease and response to therapy. MRD-negativity status and durability were assessed in MAIA and ALCYONE. MRD assessments using next-generation sequencing (10−5) occurred for patients achieving complete response (CR) or better and after at least CR at 12, 18, 24, and 30 months from the first dose. Progression-free survival (PFS) by MRD status and sustained MRD negativity lasting ≥6 and ≥12 months were analyzed in the intent-to-treat population and among patients achieving at least CR. In MAIA (D-Rd, n = 368; lenalidomide and dexamethasone [Rd], n = 369) and ALCYONE (D-VMP, n = 350; bortezomib/melphalan/prednisone [VMP], n = 356), the median duration of follow-up was 36.4 and 40.1 months, respectively. MRD-negative status and sustained MRD negativity lasting ≥6 and ≥12 months were associated with improved PFS, regardless of treatment group. However, daratumumab-based therapy improved rates of MRD negativity lasting ≥6 months (D-Rd, 14.9% vs Rd, 4.3%; D-VMP, 15.7% vs VMP, 4.5%) and ≥12 months (D-Rd, 10.9% vs Rd, 2.4%; D-VMP, 14.0% vs VMP, 2.8%), both of which translated to improved PFS vs control groups. In a pooled analysis, patients who were MRD negative had improved PFS vs patients who were MRD positive. Patients with NDMM who achieved MRD-negative status or sustained MRD negativity had deep remission and improved clinical outcomes. These trials were registered at www.clinicaltrials.gov as #NCT02252172 (MAIA) and #NCT02195479 (ALCYONE).
Cost Conversations About Anticoagulation Between Patients With Atrial Fibrillation and Their Clinicians
Giblon, Rachel , Kunneman, Marlene, Lee, Alexander I., Hargraves, Ian , Sivly, Angela , Burnett, Bruce , Gorr, Haeshik, Roldan, Victor D. Torres , Spencer-Bonilla, Gabriella, Shah, Nilay D. , Brito, Juan P. , Investigators, Shared Decision Making for Atrial Fibrillation (SDM4AFib) Trial, Haffke, Alexander, Stier, Amy, Thota, Anjali, Simpson, Benjamin , Zeballos‐Palacios, Claudia , Vanmeter, Derek , Behnken, Emma , Ting, Henry H. , Anderson, Joel, Inselman, Jonathan , Muegge, Jule , Fleming, Kirsten, Olive, Marc, Vang, Miamoua, Ferrara, Michael J. , Wambua, Mike , Organick, Paige, Cabalka, Renee, Poplau, Sara , Abullarade, Carol, Keune, Shelly, Smith, Timothy D. , Barksdale, Bryan, Peters, Roma, Price, Memrie, Watson, Connie, Wolfe, Douglas A. , Haynes, Brian, Daniels, Paul R. , Jaeger, Thomas M. , Kamath, Celia C , Branda, Megan E. , Hargraves, Ian G, Sivly, Angela L, Torres Roldan, Victor D , Brito, Juan P , Kamath, Celia , Lee, Alexander I., Bellolio, Fernanda , Jackson, Elizabeth A. , Burnett, Bruce, Noseworthy, Peter A. , Montori, Víctor M. , Investigators, Shared Decision Making for Atrial Fibrillation (SDM4AFib) Trial, LeBlanc, Annie , Hess, Erik P. , Hamilton, James, Fleming, Kirsten, Linzer, Mark , Suzuki, Takeki , Harvey, Lisa Anne , Stephens, Shannon W. , Hickey, Theresa, Guyatt, Gordon , Tomlinson, George , Gersh, Bernard J. , McBane, Robert D.

JAMA Network Open | July 13, 2021 | Volume: 4 | Issue: 7 | Pages: e2116009

10.1001/jamanetworkopen.2021.16009 | PMID 34255051 Get It

Comparison of flap reconstruction for soft tissue sarcomas of the foot and ankle
Mallett, Katherine E. , Houdek, Matthew T. , Honig, Rachel , Bakri, Karim , Rose, Peter S. , Moran, Steven L. , Honig, Rachel L, Houdek, Matthew T

Journal of Surgical Oncology | July 12, 2021 | Volume: 124 | Issue: 7 | Pages: 995-1001

10.1002/jso.26605 | PMID 34252197 Get It

Abstract Background Foot and ankle soft tissue sarcomas (STS) are challenging for reconstruction due to limited surrounding soft tissue and weight‐bearing requirements. Currently, there is a paucity of data examining the outcome of flap reconstruction following resection of a foot and ankle sarcoma. Methods We reviewed 44 (31 female, 13 male) patients with STS arising from the ankle or foot which required coverage in the form of a free ( n = 21), pedicled ( n = 13), or rotational perforator flap ( n = 10). The mean tumor size was 6 ± 5 cm, with 39 (89%) patients receiving radiotherapy. The mean follow‐up was 10 ± 7 years. Results There were no cases of amputation due to flap failure, with a 10‐year limb salvage rate of 84%. Complications occurred in 19 (43%) patients, most commonly wound infections. There was no difference in the incidence of complications between patients undergoing a free flap and pedicled or perforator flap (odds ratio = 0.97, p = 1.0); with no difference in the mean Musculoskeletal Tumor Society (MSTS) score between patients with a free flap versus a pedicled/perforator flap (84% vs. 76%, p = 0.11). Conclusion Flap reconstruction is an essential part of limb salvage for foot and ankle STS. At final follow‐up nearly all the patients are ambulatory with an acceptable MSTS score.
Characterization of a RAD51C -silenced high-grade serous ovarian cancer model during development of PARP inhibitor resistance
Hurley, Rachel M. , McGehee, Cordelia D. , Nesic, Ksenija , Weiskittel, Taylor M. , Kelly, Rebecca L. , Venkatachalam, Annapoorna , Hou, Xiaonan , Pathoulas, Nicholas M. , Meng, X. Wei, Kondrashova, Olga , Schneider, Paula A., Flatten, Karen S., Peterson, Kevin L. , Becker, Marc A., Southey, Melissa S, Harding, Thomas C., McNeish, Iain A. , Wagner, Jill M., Wakefield, Matthew J. , Scott, Clare L. , Hendrickson, Andrea E. Wahner , Karnitz, Larry M., Swisher, Elizabeth M. , Weroha, S. John , Lin, Kevin K. , Dobrovic, Alexander , Ross, Christian A, Haluska, Paul , Kaufmann, Scott H , McNeish, Iain A , Swisher, Elizabeth M , Wakefield, Matthew J , Scott, Clare L , Kondrashova, Olga , Correia, Cristina , Radke, Marc R. , Wong, Ee Ming , Lin, Kevin , Roß, Christian , Li, Hu , Kaufmann, Scott H.

NAR Cancer | July 10, 2021 | Volume: 3 | Issue: 3 | Pages: No page available

10.1093/narcan/zcab028 | PMID 34316715 Get It

Abstract Acquired PARP inhibitor (PARPi) resistance in BRCA1- or BRCA2-mutant ovarian cancer often results from secondary mutations that restore expression of functional protein. RAD51C is a less commonly studied ovarian cancer susceptibility gene whose promoter is sometimes methylated, leading to homologous recombination (HR) deficiency and PARPi sensitivity. For this study, the PARPi-sensitive patient-derived ovarian cancer xenograft PH039, which lacks HR gene mutations but harbors RAD51C promoter methylation, was selected for PARPi resistance by cyclical niraparib treatment in vivo. PH039 acquired PARPi resistance by the third treatment cycle and grew through subsequent treatment with either niraparib or rucaparib. Transcriptional profiling throughout the course of resistance development showed widespread pathway level changes along with a marked increase in RAD51C mRNA, which reflected loss of RAD51C promoter methylation. Analysis of ovarian cancer samples from the ARIEL2 Part 1 clinical trial of rucaparib monotherapy likewise indicated an association between loss of RAD51C methylation prior to on-study biopsy and limited response. Interestingly, the PARPi resistant PH039 model remained platinum sensitive. Collectively, these results not only indicate that PARPi treatment pressure can reverse RAD51C methylation and restore RAD51C expression, but also provide a model for studying the clinical observation that PARPi and platinum sensitivity are sometimes dissociated.
Abstract 215: Evaluation of Intracranial Pressure and Cerebral Perfusion Pressure in the Clot Lysis: Evaluating Accelerated Resolution of Intraventricular Hemorrhage Trial (CLEAR III)
Ziai, Wendy , Mayo, Steven, McBee, Nichol , Dlugash, Rachel , Ram, Malathi , Thompson, Richard E. , Lane, Karen , Awad, Issam A. , Mayo, Steven, Freeman, William D. , Hanley, Daniel F.

Stroke | July 3, 2021 | Volume: 47 | Issue: suppl_1 | Pages: No page available

10.1161/str.47.suppl_1.215 Get It

Background: Elevated intracranial pressure (ICP) and inadequate cerebral perfusion pressure (CPP) are mechanisms causing poor outcomes in spontaneous intraventricular hemorrhage (IVH). We characterized intracranial hypertension in severe IVH requiring extraventricular drainage (EVD). Methods: Prospective analysis of ICP in all 500 patients enrolled in the CLEAR III trial, a multicenter, double-blind, randomized study comparing EVD + intraventricular recombinant tissue plasminogen activator (rtPA) vs. EVD + placebo for treatment of obstructive IVH and intracerebral hemorrhage (ICH) volume <30cc. Maximum and minimum ICP/CPP were recorded every 4 hours until 7 days post randomization (rand), analyzed at pre-defined thresholds and compared by clinical and radiological variables. Results: of 23,406 ICP readings, maximum ICP ranged from 0-97 mmHg (median, IQR; 11,8); 90.7% (21,223) were ≤20mmHg, 1.8% >30, 0.5% >40, and 0.2% > 50mm Hg. Proportion of threshold events >20mmHg were more frequent with persistent closure of the lower ventricular system after day 3 (p=0.02), and was correlated with initial and end of treatment (72 hours post rand) ICH volumes (p=0.01, p=0.04, respectively). ICP elevation >20mmHg occurred during a required 1 hr EVD closure interval after 566/3712 (15.3%) study agent injections. Early re-opening of the EVD occurred in 3.9%. Shunting for hydrocephalus occurred in 18.6% over 1 year follow-up and was associated with % of high ICP events >20 and 30 mmHg (p=0.01 for both). After adjustment for ICH severity factors and IVH volume, % of ICP readings>20 mmHg was significantly associated with 30 and 180 day mortality (p=0.01; p=0.03 respectively), and borderline with modified Rankin Scale (mRS4-6) (p=0.09; p=0.11 respectively). Proportion of CPP readings <70mmHg was associated with day 30 poor mRS (p=0.02), with a weaker association for day 180 mRS (p=0.07). Conclusions: Elevated ICP and inadequate CPP are not infrequent during monitoring and EVD drainage in severe IVH and predict higher short and long-term mortality. Early opening of the lower ventricular system may reduce high ICP events. These results permit future correlation of ICP and CPP with treatment rendered (thrombolysis vs placebo), with upcoming unblinding of the trial.
Abstract P86: Predicting Mean Pulmonary Arterial Pressure Using Systemic Arterial Pressure (SPAP)
Steckelberg, Rachel C. , Sorajja, Paul , Ommen, Steven R., Sorajja, Paul , Nishimura, Rick A.

Circulation: Cardiovascular Quality and Outcomes | July 3, 2021 | Volume: 4 | Issue: suppl_2 | Pages: No page available

10.1161/circoutcomes.4.suppl_2.ap86 Get It

Background: The assessment of pulmonary pressure is elementary in the management of patients with pulmonary hypertension. Presently, pulmonary artery systolic pressure (PASP) can be reliably estimated using non-invasive means, but mean pulmonary pressure (MPAP) cannot be derived. The aim of this study was to derive a formula to non-invasively predict MPAP from PASP. Methods: Invasive hemodynamic pressures at steady state were examined in 198 consecutive patients who underwent right heart catheterization in the Mayo Clinic (Rochester, MN). Simple regression techniques were used to determine the relationship between MPAP and PASP separately for derivation and validation samples. Bland-Altman analysis was performed to examine predicted vs. observed MPAP values. Results: Over a wide range of MPAP (10 to 80 mmHg), MPAP and SPAP were strongly related (r2=0.89, n=198). The relation of MPAP to PASP in the derivation sample (n=100; MPAP=0.6133*SPAP + 1.1; r2=0.90) was validated in the test sample with an r2 value of 0.91 for predicted versus observed MPAP (p=x). The relation of predicted vs. observed MPAP values was significant across different degrees of pressure elevation, as well as different etiologies of pulmonary hypertension. Conclusion: MPAP can be accurately predicted from SPAP over a wide pressure range and among different etiologies for pulmonary hypertension. This relation may help to define MPAP non-invasively and assist in the clinical management of patients with pulmonary hypertension.
Assessment of serological assays for identifying high titer convalescent plasma
Farnsworth, Christopher W , Hock, Karl , Chen, Rita E. , O’Halloran, Jane A. , Goss, Charles W. , Rauseo, Adriana M. , Theel, Elitza S. , Diamond, Michael , Case, James Brett , Presti, Rachel M. , Ellebedy, Ali H. , Henderson, Jeffrey P.

Transfusion | July 3, 2021 | Volume: 61 | Issue: 9 | Pages: 2658-2667

10.1111/trf.16580 | PMID 34216156 Get It

Abstract Background The COVID‐19 pandemic has been accompanied by the largest mobilization of therapeutic convalescent plasma (CCP) in over a century. Initial identification of high titer units was based on dose–response data using the Ortho VITROS IgG assay. The proliferation of severe acute respiratory syndrome coronavirus 2 serological assays and non‐uniform application has led to uncertainty about their interrelationships. The purpose of this study was to establish correlations and analogous cutoffs between multiple serological assays. Methods We compared the Ortho, Abbott, Roche, an anti‐spike (S) ELISA, and a virus neutralization assay. Relationships relative to FDA‐approved cutoffs under the CCP emergency use authorization were identified in convalescent plasma from a cohort of 79 donors from April 2020. Results Relative to the neutralization assay, the spearman r value of the Ortho Clinical, Abbott, Roche, anti‐S ELISA assays was 0.65, 0.59, 0.45, and 0.76, respectively. The best correlative index for establishing high‐titer units was 3.87 signal‐to‐cutoff (S/C) for the Abbott, 13.82 cutoff index for the Roche, 1:1412 for the anti‐S ELISA, 1:219 by the neutralization assay, and 15.9 S/C by the Ortho Clinical assay. The overall agreement using derived cutoffs compared to a neutralizing titer of 1:250 was 78.5% for Abbott, 74.7% for Roche, 83.5% for the anti‐S ELISA, and 78.5% for Ortho Clinical. DISCUSSION Assays based on antibodies against the nucleoprotein were positively associated with neutralizing titers and the Ortho assay, although their ability to distinguish FDA high‐titer specimens was imperfect. The resulting relationships help reconcile results from the large body of serological data generated during the COVID‐19 pandemic.
Abstract 4853: Association of Physician Certification with Rates of CRT-D Implantation in Eligible Patients: Insights from the ICD Registry
Curtis, Jeptha P. , Leubbert, Jeffrey, Wang, Yongfei , Lampert, Rachel , Rathore, Saif S., Hammill, Stephen C., Heidenreich, Paul A. , Krumholz, Harlan M.

Circulation | July 3, 2021 | Volume: 118 | Issue: suppl_18 | Pages: No page available

10.1161/circ.118.suppl_18.s_950-a Get It

Current guidelines recommend cardiac resynchronization therapy (CRT-D) in appropriate patients undergoing ICD implantation. However, not all physicians who implant ICDs are trained to perform CRT-D. We examined the ICD Registry to assess whether use of CRT-D implantation varied by physician certification. We determined the certification of 2128 physicians who had submitted >=10 cases between April 2006 and June 2007. We excluded patients with a prior ICD, an epicardial lead, or aged ≤18 years, leaving 111,293 patients. Physicians were grouped into mutually exclusive categories reflecting highest current certification- Electrophysiology (EP), Cardiovascular Disease (CVD), Thoracic Surgery (TS), Internal Medicine (IM), Heart Rhythm Society alternative pathway (HRS), and Other. Patients were considered eligible for CRT-D if they met the following criteria: QRS duration >=120ms, LVEF ≪26>35%, and NYHA Class III-IV. We examined crude rates of CRT-D across physician categories and developed a logistic regression model to assess the association of physician certification and CRT-D implantation. Candidate variables included demographics, cardiac status, comorbidities, and physician volume. Odds ratios were converted to relative risks. 35,851 patients met all three eligibility criteria for CRT-D, and 28,932 (80.7%) had a CRT-D implanted. EP physicians implanted the majority of CRT-D (73.6%), with fewer CRT-D placed by CVD (20.6%), TS (0.9%), IM (0.8%), HRS (1.1%), or Other (3.1%). The crude rate of CRT-D implantation was highest among EP physicians and lower in all other categories: EP- 83.1%, CVD-75.8%, TS- 57.9%, IM- 76.5%, HRS- 77.1%, Other- 73.5% (p<0.001). In multivariable analysis, CVD and TS physicians were less likely to implant CRT-D in eligible patients compared with EP physicians (EP: Ref; CVD: RR 0.92 (0.90 – 0.94); TS: RR 0.76 (0.71– 0.85)). CRT-D rates were comparable for other physician groups (IM RR 0.95 (0.87–1.01); HRS: RR 0.97 (0.90 –1.02); Other RR 0.97 (0.93–1.00)). Among eligible patients, use of CRT-D varies by physician certification. Given the benefits of CRT-D, clinicians should consider referring eligible patients to physicians with familiarity and expertise in CRT-D implantation.
Genome-wide Interaction Analysis of Menopausal Hormone Therapy Use and Breast Cancer Risk among 62,370 Women
Kapoor, Pooja, Auer, Paul, Dennis, Joe, Wang, Qin , Bolla, Manjeet K. , Aronson, Kristan J. , Lee, Derrick , Cordina‐Duverger, Emilie, Mulot, Claire , Teras, Lauren R., Patel, Alpa V. , Hoppe, Reiner , Lo, Wing‐Yee, Brüning, Thomas , Hamann, Ute, Couch, Fergus, Ruddy, Kathryn J. , MacInnis, Robert J. , Wilkens, Lynne, Haiman, Christopher A. , Krüger, Ute , Wagner, Philippe , Vachon, Celine M. , Eliassen, Heather, Andrulis, Irene L. , Evans, D. Gareth , Ziogas, Argyrios, Orr, Nick , Linet, Martha S. , Prentice, Ross L. , Easton, Douglas F. , Chang‐Claude, Jenny , Lindström, Sara , Evans, D Gareth , Maclnnis, Robert , Orr, Nick , Wang, Xiaoliang , Kapoor, Pooja, Dunning, Alison M. , Lush, Michael J. , Michailidou, Kyriaki , Murphy, Rachel A. , Brooks‐Wilson, Angela , Guénel, Pascal , Truong, Thérèse , Teras, Lauren R. , Dossus, Laure , Kaaks, Rudolf , Czene, Kamila , Gabrielson, Marike , Hall, Per N , Eriksson, Mikael , Jung, Audrey , Becher, Heiko , Couch, Fergus J. , Larson, Nicole, Olson, Janet E. , Giles, Graham G. , Southey, Melissa C. , Marchand, Loı̈c Le , Wilkens, Lynne R. , Olsson, Håkan , Augustinsson, Annelie , Scott, Christopher, Winham, Stacey J. , Vachon, Celine M. , Perou, Charles M. , Olshan, Andrew F. , Troester, Melissa A. , Hunter, David, Eliassen, A. Heather , Tamimi, Rulla M. , Brantley, Kristen D. , Figueroa, Jonine D. , Chanock, Stephen Jacob , Ahearn, Thomas U. , García‐Closas, Montserrat , Newman, William G. , Veen, Elke M. van , Howell, Anthony , Wolk, Alicja , Håkansson, Niclas , Anton‐Culver, Hoda , Jones, Michael E. , Schoemaker, Minouk J. , Swerdlow, Anthony J. , Kitahara, Cari M. , Milne, Roger L. , Kraft, Peter

No container title available | July 2, 2021 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.21203/rs.3.rs-532921/v2 Get It

Abstract Background: Use of menopausal hormone therapy (MHT) is associated with increased risk for breast cancer. However, the relevant mechanisms and its interaction with genetic variants are not fully understood. Methods: We conducted a genome-wide interaction analysis between MHT use and genetic variants for breast cancer risk in 27,585 cases and 34,785 controls from 26 observational studies. All women were post-menopausal and of European ancestry. Multivariable logistic regression models were used to test for multiplicative interactions between genetic variants and current MHT use. We considered interaction p-values<5x10-8 as genome-wide significant, and p-values<1x10-5 as suggestive. Linkage disequilibrium (LD)-based clumping was performed to identify independent candidate variants.Results: None of the 9.7 million genetic variants tested for interactions with MHT use reached genome-wide significance. Only 213 variants, representing 18 independent loci, had p-values<1x105. The strongest evidence was found for rs4674019 (p-value=2.27x10-7), which showed genome-wide significant interaction (p-value=3.8x10-8) with current MHT use when analysis was restricted to population-based studies only. Limiting the analyses to combined estrogen-progesterone MHT use only or to estrogen receptor (ER) positive cases did not identify any genome-wide significant evidence of interactions. Conclusions: In this large genome-wide SNP-MHT interaction study of breast cancer, we found no strong support for common genetic variants modifying the effect of MHT on breast cancer risk. These results suggest that common genetic variation has limited impact on the observed MHT–breast cancer risk association.
Abstract CT026: A phase II trial of neratinib (NER) or NER plus fulvestrant (FUL) (N+F) in HER2 mutant, non-amplified (HER2mut) metastatic breast cancer (MBC): Part II of MutHER
Cynthia, X. , Nangia, Julie R. , Lu, Janice , Valdez-Albini, Frances, Jones, Jason M. , Thomas, Shana , Anderson, J. L. , Haas, Brittney , Hamann, Kimberly M., Bryce, Richard , Lalani, Alshad S. , Kimmick, Gretchen , Pegram, Mark D. , Bose, Ron , Luo, Jingqin , Freedman, Rachel A. , Pluard, Timothy , Cobleigh, Melody , Lin, Nancy U. , Winer, Eric P. , Marcom, Paul Kelly , Anderson, Jill, Carey, Lisa A. , Goetz, Matthew P. , Gao, Feng , Ellis, Matthew J.

Cancer Research | July 1, 2021 | Volume: 81 | Issue: 13_Supplement | Pages: CT026-CT026

10.1158/1538-7445.am2021-ct026 Get It

Abstract Introduction: The irreversible pan-HER inhibitor NER showed modest single agent activity for HER2mut MBC in Part I of MutHER trial. In Part II, we hypothesized that (1) N+F would improve activity in estrogen receptor positive (ER+) HER2mut MBC due to ER-HER2 crosstalk and (2) dual HER2 blockade by adding trastuzumab at disease progression (PD) could overcome resistance. Methods: Pts with ER+HER2mut MBC were enrolled to 2 cohorts (FUL treated or naive) to receive N+F with diarrhea prophylaxis. ER- pts received NER in an exploratory ER- cohort. Trastuzumab was added at PD if approved by insurance. Simon's Minimax 2-stage phase II design with the primary endpoint of clinical benefit rate (CBR: rates of complete/partial response [CR/PR] plus stable disease [SD] &gt;24 weeks [wks]), with anticipated vs null hypothesis being CBR of 55% vs 35% (FUL treated) or 65% vs 40% (FUL naïve) with 80% power, 1 sided 0.05 alpha, was used. Secondary endpoints included progression free survival (PFS) and adverse events (AEs). Serial blood samples were analyzed for circulating tumor DNA (ctDNA) by Guardant360 for concomitant mutations, HER2mut variant allele frequency (VAF) dynamics, and resistance mechanisms. Results: Between Sep. 2015 and Oct. 2020, 40 pts with HER2mut MBC were enrolled, completing the 1st stage of each ER+ cohort. 35 pts (21 FUL treated, 10 FUL naïve, 4 ER-) were evaluable for response, with median age 63 (35-82) years, 3 (0-12) prior MBC regimen, lobular BC in 13 (37%) and visceral mets in 32 (91%) pts. 21 (68%) ER+ pts had prior CDK4/6 inhibitor. All but 1 pt has come off study due to PD. Table 1 shows the efficacy by cohort. Further enrollment is closed per protocol. Adding trastuzumab at PD induced CB in 4 (3 PR, 1 SD≥24 wks) of 5 pts (1 ER-, 4 ER+), with PFS 28 (95% CI 18~NA) wks. Common AEs across cohorts were diarrhea (G3 21%) and fatigue (G3 5%). No G4 AEs. ctDNA HER2mut was detected in 72% (23/32) baseline (BL) samples tested. In pts with paired samples, HER2mut VAF decreased at C1D15/C2D1 from BL in 75% (15/20) and rose in 89% (16/18) at PD. Acquired HER2mut, including the T798I gatekeeper mutation, were detected in 2 pts at PD. Mutations in TP53 (53%), PIK3CA (43%), and CDH1 (35%) were common, but none significantly associated with PFS in all or ER+ pts. Conclusions: NER, or N+F, is active for HER2mut MBC with good tolerability. Adding trastuzumab at PD induced further response, supporting dual HER2 blockade for HER2mut MBC. Table 1.EfficacyCohortFUL treatedFUL naïveER-Best Response, n evaluablen = 21n = 10n = 4CR, n100PR, n431SD (≥ 24 wks), n300SD (&lt; 24 wks), n1030PD, n343CBR, n with CB/total n evaluable, % (95% CI)8 of 20*, 40% (19~64%)3 of 10, 30% (7~65%)1 of 4, 25% (0.6~81%)mPFS (95% CI), wks, ITT (n)24 (16~31) wks, (n = 24)20 (8~NA) wks, (n = 11)8.5 (8~NA) wks, (n = 5)*20 of 21 pts are evaluable for CBR in the FUL treated Cohort as 1 pt had SD as best response and treatment is still ongoing. ITT (intent to treat) population is used for mPFS estimate. Citation Format: Cynthia X. Ma, Jingqin Luo, Rachel A. Freedman, Timothy Pluard, Julie Nangia, Janice Lu, Frances Valdez-Albini, Melody Cobleigh, Jason Jones, Nancy U. Lin, Eric Winer, P. Kelly Marcom, Shana Thomas, Jill Anderson, Brittney Haas, Kimberly M. Hamann, Richard Bryce, Alshad S. Lalani, Lisa Carey, Matthew Goetz, Feng Gao, Gretchen Kimmick, Mark Pegram, Matthew J. Ellis, Ron Bose. A phase II trial of neratinib (NER) or NER plus fulvestrant (FUL) (N+F) in HER2 mutant, non-amplified (HER2mut) metastatic breast cancer (MBC): Part II of MutHER [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT026.