Weckstein, Douglas

PURPOSE Long-term outcomes of patients with stage I human epidermal growth factor receptor 2 (HER2)–positive breast cancer receiving adjuvant trastuzumab emtansine (T-DM1) remain undefined, and prognostic predictors represent an unmet need. METHODS In the ATEMPT phase II trial, patients with stage I centrally confirmed HER2-positive breast cancer were randomly assigned 3:1 to adjuvant T-DM1 for 1 year or paclitaxel plus trastuzumab (TH). Coprimary objectives were to compare the incidence of clinically relevant toxicities between arms and to evaluate invasive disease-free survival (iDFS) with T-DM1. Correlative analyses included the HER2DX genomic tool, multiomic evaluations of HER2 heterogeneity, and predictors of thrombocytopenia. RESULTS After a median follow-up of 5.8 years, 11 iDFS events were observed in the T-DM1 arm, consistent with a 5-year iDFS of 97.0% (95% CI, 95.2 to 98.7). At 5 years, the recurrence-free interval (RFI) was 98.3% (95% CI, 97.0 to 99.7), the overall survival was 97.8% (95% CI, 96.3 to 99.3), and the breast cancer-specific survival was 99.4% (95% CI, 98.6 to 100). Comparable iDFS was observed with T-DM1 irrespective of tumor size, hormone receptor status, centrally determined HER2 immunohistochemical score, and receipt of T-DM1 for more or less than 6 months. Although ATEMPT was not powered for this end point, the 5-year iDFS in the TH arm was 91.1%. Among patients with sufficient tissue for HER2DX testing (n = 187), 5-year outcomes significantly differed according to HER2DX risk score, with better RFI (98.1% v 81.8%, hazard ratio [HR], 0.10, P = .01) and iDFS (96.3% v 81.8%, HR, 0.20, P = .047) among patients with HER2DX low-risk versus high-risk tumors, respectively. CONCLUSION Adjuvant T-DM1 for 1 year leads to outstanding long-term outcomes for patients with stage I HER2-positive breast cancer. A high HER2DX risk score predicted a higher risk of recurrence in ATEMPT.

5006 Background: The PRESTO trial (NCT03009981) showed that in patients with biochemically relapsed prostate cancer following radical prostatectomy with a PSA doubling time of ≤ 9 months and without evidence of metastatic disease by conventional imaging, intensified androgen receptor blockade for 52 weeks (androgen deprivation therapy [ADT] plus apalutamide [Apa], or ADT plus Apa and abiraterone acetate [Abi] plus prednisone) prolonged PSA progression-free survival compared to ADT alone (Aggarwal et al, JCO 2024). Here we report the HRQOL results. Methods: HRQOL measures included the Hot Flash Related Daily Interference Scale (HFRDIS), Expanded Prostate Cancer Index Composite (EPIC)-26 Sexual domain, PROMIS Fatigue Short Form and EQ-5D-5L, which assesses overall HRQOL in the 504 randomized patients. Published minimally important difference thresholds for these HRQOL measures are: HFRDIS 1.66 points, EPIC Sexual 10-12, PROMIS Fatigue 3-5, and EQ-5D-5L 0.06. General linear mixed modeling was used to estimate between-arm mean differences in HRQOL according to an intent-to-treat approach. Results: Mean changes from baseline to end of treatment (EOT) for each arm and for each HRQOL measure are summarized in Table. No statistically significant mean difference was reported between intensified androgen receptor blockade (Arm B, Arm C) vs ADT alone (Arm A) in any HRQOL measure. Further, numerical differences across arms for all HRQOL measures are below published minimally clinically important difference thresholds. Conclusions: Intensified androgen receptor blockade with Apa or Apa/Abi added to 52 weeks of ADT improves PSA progression-free survival without negatively affecting HRQOL. These HRQOL results add further support to intensification of androgen blockade in patients with high-risk biochemically recurrent prostate cancer. Clinical trial information: NCT03009981 . [Table: see text]

PURPOSE Patients with biochemically recurrent prostate cancer (BRPC) after radical prostatectomy and a short PSA doubling time are at risk for distant metastases. Apalutamide, an androgen receptor antagonist, and abiraterone acetate plus prednisone (AAP) prolong survival in the metastatic setting. We evaluated whether intensification of androgen-deprivation therapy (ADT) improves outcomes in BRPC. PATIENTS AND METHODS PRESTO is a randomized phase III, open-label trial in patients with BRPC and PSA doubling time ≤9 months (ClinicalTrials.gov identifier: NCT03009981 ). Patients were randomly assigned 1:1:1 to receive a finite 52-week treatment course with ADT control, ADT + apalutamide, or ADT + apalutamide + AAP. The primary end point was PSA progression-free survival (PSA-PFS), defined as serum PSA >0.2 ng/mL after treatment completion. RESULTS Five hundred three patients were enrolled. The median PSA was 1.8 ng/mL (IQR, 1.0-3.6). At the first planned interim analysis, both experimental arms significantly prolonged PSA-PFS compared with the control arm (median, 24.9 months for ADT + apalutamide v 20.3 months for ADT; hazard ratio [HR], 0.52 [95% CI, 0.35 to 0.77]; P = .00047; median, 26.0 months for ADT + apalutamide + AAP v 20.0 months for ADT; HR, 0.48 [95% CI, 0.32 to 0.71]; P = .00008). Median time to testosterone recovery did not differ across treatment arms. The most common grade ≥3 adverse event was hypertension (7.5%, 7.4%, and 18% in ADT, ADT + apalutamide, and ADT + apalutamide + AAP arms, respectively). CONCLUSION Intensified AR blockade for a finite duration prolongs PSA-PFS with a manageable safety profile, without adversely affecting time to testosterone recovery. The addition of apalutamide to ADT should be considered in patients with high-risk BRPC.

5077 Background: In the phase 3 PRESTO study, intensified androgen deprivation therapy (ADT) with apalutamide (Apa) with or without abiraterone acetate plus prednisone (AAP), administered for a finite treatment period of 52 weeks, prolonged prostate-specific antigen progression-free survival (PSA PFS) in pts with high-risk biochemically relapsed prostate cancer (BRPC). We evaluated the association between PSA nadir within 3 months of treatment initiation with subsequent PSA PFS in this study. Methods: PRESTO is a randomized phase 3, open-label trial in pts with BRPC following radical prostatectomy (RP) and PSA doubling time (PSADT) ≤ 9 months, without distant metastases on conventional imaging (NCT03009981). Pts were randomized 1:1:1 to receive a finite 52-week treatment course with ADT, ADT + Apa, or ADT + Apa + AAP, stratified by PSADT (< 3 vs 3–9 months), with post-treatment follow-up. The association between PSA nadir within the first three months on treatment with subsequent PSA PFS was analyzed in a post hoc fashion. Results: 504 pts were randomized to ADT alone (N = 167), ADT + Apa (N = 168) or ADT + Apa + AAP (N = 169). 463 pts were evaluable for PSA nadir at 3 months. Across the three treatment arms, a PSA nadir of less than 0.1, between 0.1 – 0.2, and ≥ 0.2 ng/mL within the first three months of treatment was observed in 86.3%, 4.4%, and 9.3% of patients, respectively. A PSA nadir of < 0.2 ng/mL was reached within 3 months of treatment initiation in 79.8%, 96.9%, and 95.0% of pts randomized to the ADT, ADT + Apa, and ADT + Apa + AAP arms, respectively. The association between time to PSA nadir and subsequent PSA PFS was -0.30 (standard error = 0.03, Kendall’s tau modified for bivariate censoring), and median time to PSA nadir was 2.0 months (interquartile range 1.12 – 4.76 months). Failure to reach a PSA nadir < 0.2 ng/mL within the first three months of treatment was associated with a significantly shorter PSA PFS compared to pts with a PSA nadir ≤ 0.1 ng/mL (median PSA PFS of 13.9 vs. 22.8 months from 3 months post-treatment initiation; hazard ratio = 5.60, 95% CI: 3.58 – 8.75, p < 0.0001). There was also a significant difference in PSA PFS in those with a three-month PSA nadir between 0.1 – 0.2 vs ≤ 0.1 ng/mL (median PSA PFS 17.4 vs 22.8 months, HR = 2.63, 95:CI: 1.49 – 4.63, p = 0.0008). Conclusions: Using a landmark analysis at 3 months, a failure to reach PSA nadir less than 0.1 ng/mL within three months following initiation of ADT in BRPC is associated with shorter time to subsequent progression following treatment discontinuation. Follow-up is ongoing to integrate genomic profiling of primary prostate cancer tissues and whole blood RNA in pts with suboptimal PSA nadir to identify potential markers of relative androgen pathway inhibitor resistance. Clinical trial information: NCT03009981 .

208 Background: In the Phase 3 PRESTO study, intensified androgen deprivation therapy (ADT) with apalutamide (APA) with or without abiraterone acetate plus prednisone (AAP), administered for a finite treatment period of 52 weeks, prolonged prostate-specific antigen progression-free survival (PSA PFS) in pts with high-risk biochemically relapsed prostate cancer (BRPC). We evaluated baseline factors associated with PSA PFS in this study. Methods: PRESTO is a randomized phase 3, open-label trial in pts with BRPC following radical prostatectomy (RP) and PSA doubling time (PSADT) ≤ 9 months (mo), without distant metastases on conventional imaging (NCT03009981). Pts were randomized 1:1:1 to receive a finite 52-week treatment course with ADT, ADT + APA, or ADT + APA + AAP, stratified by PSADT (< 3 vs 3–9 mo), with post-treatment follow-up. Baseline factors associated with PSA PFS including Gleason sum at RP (6-7, 8, ≥ 9) were analyzed in a post hoc fashion. Results: 504 pts were randomized to ADT alone (N = 167), ADT + APA (N = 168) or ADT + APA + AAP (N = 169). Baseline patient characteristics including Gleason sum at diagnosis, serum PSA and PSADT at study entry, time interval from radical prostatectomy, and receipt of prior radiation (none, adjuvant, salvage) were well balanced across the three treatment arms. At the first planned interim analysis, both experimental arms significantly prolonged PSA PFS compared to the control arm (median 24.9 mo for ADT + APA vs 20.3 mo for ADT, HR = 0.52 (95% CI: 0.35–0.77); median 26.0 mo for ADT + APA + AAP vs 20.0 mo for ADT, HR = 0.48 (95% CI: 0.32–0.71)). Across the study cohort, Gleason sum ≥ 9 at diagnosis was associated with shorter PSA PFS (median 21.9 mo for Gleason ≥ 9 vs. 31.1 mo for Gleason 8 vs. 25.2 mo for Gleason 6-7, log-rank p-value = 0.0409). In addition, within each treatment arm, a shorter observed median PSA PFS was detected for patients with Gleason ≥ 9 prostate cancer. Serum PSA and PSADT at study entry, time from prior radical prostatectomy, and prior radiation were not associated with PSA PFS in the overall study cohort or in individual study arms. Conclusions: Gleason sum ≥ 9 prostate cancer at diagnosis was associated with shorter time to PSA progression following subsequent intensified ADT administered for a finite treatment interval in BRPC. Follow-up is ongoing to integrate genomic profiling of primary prostate cancer tissue with these results and validate with longer term endpoints including metastasis-free survival. Clinical trial information: NCT03009981 .

Abstract Background: The ATEMPT trial primary analysis found that one year of adjuvant trastuzumab emtansine (T-DM1) achieved a 3-year iDFS of 97.8% for patients with stage I HER2+ breast cancer, but was not associated with fewer clinically relevant toxicities (CRTs) compared with paclitaxel and trastuzumab (TH). In this end-of-study analysis, we report 5-year survival outcomes and correlative analyses from the trial. Methods: Patients with stage I centrally confirmed HER2+ breast cancer were randomly assigned 3:1 to adjuvant T-DM1 for one year or TH and received T-DM1 3.6 mg/kg IV every 3 weeks for 17 cycles or paclitaxel 80 mg/m2 IV with weekly trastuzumab IV followed by trastuzumab for 9 months. The co-primary objectives were to compare the incidence of CRTs between the 2 arms and to evaluate iDFS in patients receiving T-DM1. To investigate proteomic correlates of recurrence, spatial proteomic analyses were performed on samples from 13 patients experiencing iDFS events (cases) and 24 matched controls using the NanoString GeoMx Digital Spatial Profiler. The impact of HER2 heterogeneity on outcomes was investigated among 17 cases and 51 matched controls by fluorescence in-situ hybridization (FISH). HER2 genetic heterogeneity was assessed by scrutinizing the whole tumor area and defined as the occurrence of HER2 gene amplification in &gt;5% but &lt; 50% invasive tumor cells. The risk of recurrence was evaluated centrally with the HER2DX genomic assay from 225 primary tumor samples. Germline whole genome sequencing (WGS) was conducted among 55 patients experiencing T-DM1-induced thrombocytopenia and/or bleeding and 55 matched controls to identify genomic correlates for this side effect. Results: A total of 497 patients who initiated protocol therapy were included in this analysis (383 T-DM1 and 114 TH). After a median follow up 5.8 years, among patients receiving T-DM1 there were a total of 11 iDFS events, with 3 distant recurrences. The 5-year iDFS for T-DM1 was 97.0% (95% CI, 95.3-98.8%), the 5-year recurrence-free interval (RFI) was 98.6% (95% CI: 97.4-99.8%) and the 5-year overall survival (OS) for T-DM1 was 97.8 % (95% CI, 96.3-99.3%). Although the study was not powered to evaluate the efficacy of TH, among the 114 patients receiving TH, a total of 9 iDFS events were observed, including 2 distant events; the 5-year iDFS with TH was 91.3% (95% CI: 86.0-96.9%), 5-year RFI was 93.3% (95% CI: 88.6-98.2%) and 5-year OS was 97.9% (95% CI: 95.2-100%). A total of 56 samples were evaluable for heterogeneity analyses, among which 14% (n=8) harbored HER2 genetic heterogeneity. Spatial proteomic analyses found that NF1 (adjusted p=0.72 × 10-6) and CTLA-4 (adjusted p=0.15 × 10-3) were significantly upregulated in primary samples from cases, while cleaved caspase 9, CD25, GITR, ICOS, p53 and PD-L2 were significantly upregulated in controls (all with adjusted p&lt; 0.05). Germline WGS found that the top gene associations with thrombocytopenia and thrombocytopenia or bleeding were ALMS1 (p=0,19 × 10-3) and APBA3 (p=0,23 × 10-3), respectively, although none reaching the threshold for genome wide significance. rs62143195 and rs114169776 were the top single nucleotide polymorphisms associated with thrombocytopenia and thrombocytopenia or bleeding, respectively. Data on the impact of HER2 heterogeneity and of HER2DX score on survival outcomes will be presented. Conclusion: With longer follow-up, adjuvant T-DM1 confirmed outstanding long-term outcomes among patients with stage I HER2+ breast cancer, demonstrating a 5-year RFI of 98.6%. Spatial proteomic analyses identified a potential association between NF1 and CTLA-4 expression with recurrence. Details on the impact of HER2 heterogeneity and HER2DX assay on prognosis will be presented. Citation Format: Paolo Tarantino, Nabihah Tayob, Chau T Dang, Denise Yardley, Steven J. Isakoff, Vicente Valero, Meredith Faggen, Therese Mulvey, Ron Bose, Douglas Weckstein, Antonio C. Wolff, Katherine Reeder-Hayes, Hope Rugo, Bhuvaneswari Ramaswamy, Dan Zuckerman, Lowell Hart, Vijayakrishna K. Gadi, Michael Constantine, Kit Cheng, Audrey Merrill Garrett, Paul K. Marcom, Kathy S. Albain, Patricia DeFusco, Nadine Tung, Blair Ardman, Rita Nanda, Rachel C. Jankowitz, Mothaffar Rimawi, Vandana Abramson, Paula R. Pohlmann, Catherine Van Poznak, Andres Forero-Torres, Minetta C. Liu, Kathryn Ruddy, Yue Zheng, Romualdo Barroso-Sousa, Adrienne Waks, Michelle K. DeMeo, Molly K. DiLullo, Giuseppe Curigliano, Harold Burstein, Ann Partridge, Eric Winer, Giuseppe Viale, Winnie Hui, Elizabeth A. Mittendorf, Bryan P. Schneider, Aleix Prat, Ian Krop, Sara Tolaney. Adjuvant Trastuzumab Emtansine Versus Paclitaxel plus Trastuzumab for Stage I HER2+ Breast Cancer: 5-year results and correlative analyses from ATEMPT (TBCRC033) [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 PD18-01.

Abstract Background Combination irinotecan and cetuximab is approved for irinotecan-refractory metastatic colorectal cancer (mCRC). It is unknown if adding bevacizumab improves outcomes. Patients and Methods In this multicenter, randomized, double-blind, placebo-controlled phase II trial, patients with irinotecan-refractory RAS-wildtype mCRC and no prior anti-EGFR therapy were randomized to cetuximab 500 mg/m2, bevacizumab 5 mg/kg, and irinotecan 180 mg/m2 (or previously tolerated dose) (CBI) versus cetuximab, irinotecan, and placebo (CI) every 2 weeks until disease progression or intolerable toxicity. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), objective response rate (ORR), and adverse events (AEs). Results The study closed early after the accrual of 36 out of a planned 120 patients due to changes in funding. Nineteen patients were randomized to CBI and 17 to CI. Baseline characteristics were similar between arms. Median PFS was 9.7 versus 5.5 months for CBI and CI, respectively (1-sided log-rank P = .38; adjusted hazard ratio [HR] = 0.64; 95% confidence interval [CI], 0.25-1.66). Median OS was 19.7 versus 10.2 months for CBI and CI (1-sided log-rank P = .02; adjusted HR = 0.41; 95% CI, 0.15-1.09). ORR was 36.8% for CBI versus 11.8% for CI (P = .13). Grade 3 or higher AEs occurred in 47% of patients receiving CBI versus 35% for CI (P = .46). Conclusion In this prematurely discontinued trial, there was no significant difference in the primary endpoint of PFS between CBI and CI. There was a statistically significant improvement in OS in favor of CBI compared with CI. Further investigation of CBI for the treatment of irinotecan-refractory mCRC is warranted. Clinical Trial Registration: NCT02292758

PURPOSE The ATEMPT trial was designed to determine if treatment with trastuzumab emtansine (T-DM1) caused less toxicity than paclitaxel plus trastuzumab (TH) and yielded clinically acceptable invasive disease-free survival (iDFS) among patients with stage I human epidermal growth factor receptor 2–positive (HER2+) breast cancer (BC). METHODS Patients with stage I centrally confirmed HER2+ BC were randomly assigned 3:1 to T-DM1 or TH and received T-DM1 3.6 mg/kg IV every 3 weeks for 17 cycles or T 80 mg/m 2 IV with H once every week × 12 weeks (4 mg/kg load →2 mg/kg), followed by H × 39 weeks (6 mg/kg once every 3 weeks). The co-primary objectives were to compare the incidence of clinically relevant toxicities (CRTs) in patients treated with T-DM1 versus TH and to evaluate iDFS in patients receiving T-DM1. RESULTS The analysis population includes all 497 patients who initiated protocol therapy (383 T-DM1 and 114 TH). CRTs were experienced by 46% of patients on T-DM1 and 47% of patients on TH ( P = .83). The 3-year iDFS for T-DM1 was 97.8% (95% CI, 96.3 to 99.3), which rejected the null hypothesis ( P < .0001). Serially collected patient-reported outcomes indicated that patients treated with T-DM1 had less neuropathy and alopecia and better work productivity compared with patients on TH. CONCLUSION Among patients with stage I HER2+ BC, one year of adjuvant T-DM1 was associated with excellent 3-year iDFS, but was not associated with fewer CRT compared with TH.

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) gr<2; ≤1 prior chemotx regimens for advanced or MBC. Asymptomatic brain mets with stable MRIs for >3 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 .

Abstract Background: CRA is a surrogate for ovarian toxicity and associated risk of infertility and long-term menopausal symptoms. Therefore, it is important to assess and report the rate of CRA when we study a new neoadjuvant treatment regimen. In the Adjuvant Paclitaxel and Tratuzumab (APT) trial, we found that CRA rate associated with adjuvant TH (12 weeks of paclitaxel and a year of trastuzumab) for human epidermal growth factor receptor-2 (HER2)-positive breast cancer was lower than historically seen with cyclophosphamide-based regimens. The ATEMPT trial allowed a direct comparison of the CRA rate associated with TDM1 and TH. Methods: The ATEMPT trial randomized patients (pts) with Stage I HER2+ breast cancer 3:1 to T-DM1 3.6 mg/kg IV every 3 weeks (w) x17 vs. T 80 mg/m2 IV with H qw x 12 (4 mg/kg load →2 mg/kg), followed by H (6 mg/kg q3w x 13). Participants who reported that they were premenopausal at enrollment were asked to complete menstrual surveys at baseline and every 6-12 months throughout a 36 month follow-up period. For this analysis, CRA was defined as report of no menstruation within the prior six months on a survey completed 18 months after enrollment. Results: Of 512 ATEMPT enrollees, 497 began protocol therapy, 130 (26%) were premenopausal at enrollment and answered baseline menstrual questions, 42 of these 130 were excluded from the current analyses because they did not complete the 18-month survey, and 7 of the remaining 88 had received gonadotropin-releasing hormone agonist before 18 months, leaving 81 for analysis. None had undergone hysterectomy or oophorectomy. Median age was 44 (range 23-53) among the TH patients (n=20), and 46 (range 34-54) among the T-DM1 patients (n=61). On the 18-month survey, 45% of women treated with TH reported at least one one episode of menses during the prior 6 months compared to 75% of women in the T-DM1 arm (p=0.011). Among those ≤ 40 years old, 50% of TH patients and 100% of T-DM1 patients reported menstruation at that timepoint. Please see Table for additional data in subgroups. Conclusions: In this relatively small sample, CRA at 18 months was less common after adjuvant T-DM1 than after TH (though even with TH, nearly half of women did menstruate after chemotherapy, even in the subset aged 41+). This will be reassuring to young patients with HER2-positive breast cancer who seek to maintain ovarian function. Larger studies are needed to confirm this finding and to assess a possible differential impact of these drugs on subgroups based on age, endocrine therapy, and body mass index. Additional research should also focus on menopausal symptoms and actual fertility after receipt of T-DM1. Menstruation in 61 T-DM1 arm patients with informative surveys at 18 monthsMenstruation in 20 TH arm patients with informative surveys at 18 monthsAge at study entry95% CI95% CI≤4012/12 (100%)74-100%4/8 (50%)16-84%41+34/49 (69%)55-82%5/12 (42%)15-72%BMI&lt;3040/52 (77%)63-87%6/16 (38%)15-65%30+6/9 (67%)30-93%3/4 (75%)19-99%Endocrine therapy currentlyYes27/39 (69%)52-83%2/12 (17%)2-48%No19/22 (86%)65-97%7/9 (78%)40-97% Citation Format: Kathryn J. Ruddy, Lorenzo Trippa, Jiani Hu, William T. Barry, Chau T. Dang, Denise A. Yardley, Steven J. Isakoff, Vincente V. Valero, Meredith G. Faggen, Therese M. Mulvey, Ron Bose, Douglas J. Weckstein, Antonio C. Wolff, Katherine E. Reeder-Hayes, Hope S. Rugo, Bhuvaneswari Ramaswamy, Dan S. Zuckerman, Lowell L. Hart, Vijayakrishna K. Gadi, Michael Constantine, Kit L. Cheng, Frederick M. Briccetti, Bryan P. Schneider, A. Merrill Garrett, P. Kelly Marcom, Kathy S. Albain, Patricia A. DeFusco, Nadine M. Tung, Blair M. Ardman, Rita Nanda, Rachel C. Jankowitz, Michelle K. DeMeo, Harold J. Burstein, Eric P. Winer, Ian E. Krop, Ann H. Partridge, Sara M. Tolaney. Chemotherapy-related amenorrhea (CRA) after adjuvant trastuzumab emtansine (T-DM1) compared to paclitaxel in combination with trastuzumab (TH) (TBCRC033: ATEMPT trial) [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 P2-13-02.