Abstract PD18-01: Adjuvant Trastuzumab Emtansine Versus Paclitaxel plus Trastuzumab for Stage I HER2+ Breast Cancer: 5-year results and correlative analyses from ATEMPT (TBCRC033)

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 >5% but < 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< 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.

Adjuvant Trastuzumab Emtansine Versus Paclitaxel in Combination With Trastuzumab for Stage I HER2-Positive Breast Cancer (ATEMPT): A Randomized Clinical Trial

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/m² 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.

A randomized Phase II trial in patients with carcinoma of an unknown primary site

BACKGROUND

Current therapy for patients with carcinoma of an unknown primary site (CUP) is inadequate. To develop less toxic and more effective therapies for patients with CUP, a multicenter, randomized, Phase II study was conducted. Patients with CUP received either carboplatin and etoposide (CE) or a combination of paclitaxel, 5-fluorouracil, and leucovorin (TFL).

METHODS

Patients randomized to Arm A received paclitaxel, 175 mg/m(2), intravenously over 3 hours on Day 1 followed by leucovorin, 300 mg, over 30-60 minutes and 5-fluorouracil, 350 mg/m(2), both intravenously on Days 1-3. Patients randomized to Arm B received etoposide, 100 mg/m(2), intravenously on Days 1-3 and carboplatin at an area under the curve of 6 on Day 1 only. The cycles in both treatment arms were repeated every 28 days. Patients were followed for tumor response, survival, and toxicity.

RESULTS

Thirty-four patients were enrolled, 32 of whom were evaluable for response. An identical overall response rate of 19% (95% confidence interval, 4-45%) was noted in each treatment arm. The median survival for the entire study population was 194 days. The median survivals observed in Arm A and Arm B were 251 days and 194 days, respectively (P = 0.91 [difference not significant]). Hematologic toxicity on Arm B was considerable with 29% of the patients developing neutropenia and fever. Toxicity on Arm A was modest.

CONCLUSIONS

In this randomized Phase II trial, CE and TFL appeared to have modest activity in CUP patients, with response rates similar to those reported with previously described chemotherapy regimens. Toxicity with CE was more severe than expected, although TFL was found to be well tolerated.

Risk factors for ectopic pregnancy in a rural population

BACKGROUND AND OBJECTIVES

The study determined the frequency of common risk factors in patients with ectopic pregnancy in a rural-based population (communities with a population less than 60,000).

METHODS

The complete medical records were reviewed of all patients with ectopic pregnancy who presented from 1986 through 1992 to the emergency department of a large, rural referral hospital with 65,000 annual visits.

RESULTS

Among 126 patients with ectopic pregnancy, the predominant risk factors were a history of infertility in 35% and prior tubal operation in 38%. Pelvic inflammatory disease was a risk factor in 17%, a prior ectopic pregnancy in 16%, and a prior appendectomy or pelvic operation in 13%. No risk factor was identified in 47% of the patients.

CONCLUSION

In rural populations, the frequency of common risk factors for ectopic pregnancy is different from that cited in studies of urban populations. Frequently, patients in rural populations have no risk factors whatsoever.

Paclitaxel and 5-fluorouracil in metastatic breast cancer: the US experience

Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) is an effective drug in the treatment of metastatic breast cancer (MBC). In the salvage setting, 5-fluorouracil (5-FU) and folinic acid have proved to be effective against MBC as well. Recent preclinical data suggest that paclitaxel plus 5-FU has additive cytotoxicity. Given these observations, we initiated a phase II trial in which 38 women with MBC have been treated with a combination of all three drugs. All patients are currently evaluable for toxicity and 34 are evaluable for response. All women had histologically proven and assessable disease. Patients with prior exposure to paclitaxel were ineligible. Patient characteristics include a median age of 51 years (age range, 31 to 73 years) and a median performance status of 1 (range, 0 to 2). Thirty-three patients have received prior chemotherapy, of whom 23 had adjuvant chemotherapy only. Fifty-eight percent of the patients (22 of 38) had received prior doxorubicin or mitoxantrone; four patients had only hormonal therapy. Four patients had bone-only disease, and three patients had lymphangitic spread or cytologically positive pleural effusion as the only evaluable disease. Treatment consisted of paclitaxel 175 mg/m2 over 3 hours (day 1 only), followed by folinic acid 300 mg over 1 hour, followed by 5-FU 350 mg/m2 on days 1 to 3. Patients received standard paclitaxel premedications. To date, 175 cycles have been administered (median cycle length, 29 days; median number of cycles per patient, five). Toxicities included grade 3/4 infections in nine cycles (5%), grade 3/4 mucositis in three cycles, grade 3/4 nausea/vomiting in three cycles, grade 1 paresthesias in 12 patients (32%), alopecia 100%, and 17 cycles (10%) associated with dose reduction. Based on Cancer and Leukemia Group B toxicity criteria, arthralgia/myalgias were modest and graded mild (32 cycles), moderate (nine cycles), or severe (two cycles). There were two major hypersensitivity reactions, prompting removal of those patients from further protocol treatment. Four patients are unassessable for response due to hypersensitivity reactions (two) and unevaluable disease (two). Among the 34 patients evaluable for response, there were three complete responses, 18 partial responses, one minor response, nine stable disease, and three progressive disease (response rate, 62%). Responses were seen in patients who had received prior doxorubicin or mitoxantrone (11 of 22 patients) and in anthracycline/naive patients (10 of 16 patients). Responses were observed in all metastatic sites: soft tissue, viscera, and bone. Paclitaxel/5-FU/folinic acid appears to be an effective and well-tolerated outpatient regimen for women with MBC, even after failure of anthracycline-containing therapy.