Open-label, phase II trial of afatinib, with or without vinorelbine (V), for the treatment of HER2-overexpressing inflammatory breast cancer (IBC).

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. TPS650-TPS650 ◽  
Author(s):  
Charles Swanton ◽  
Jamie Cromer ◽  

TPS650 Background: IBC is an aggressive and rare form of BC (1–6% cases). Despite recent treatment advances, prognosis remains poor, with 3-yr survival rate of 40 vs 85% in non-IBC. IBC commonly lack ER/PR and more frequently harbour HER2 gene amplification (~40%), and EGFR overexpression (~30%) associated with poor prognosis. Recent data reported clinical efficacy of lapatinib, a reversible EGFR/HER2 inhibitor, in trastuzumab (T) naïve/resistant HER2 positive IBC. Afatinib is an irreversible ErbB Family Blocker with preclinical activity in T-resistant cell lines, HER2-positive tumor xenografts and HER2-negative SUM 149 xenograft model derived from an IBC cell line. Its clinical efficacy was shown in heavily pre-treated, HER2-positive metastatic BC pts who progressed after T, with PR in 10% and clinical benefit in 46% of pts. The purpose of this biomarker-driven study is to investigate efficacy and safety of afatinib alone and in combination with V upon progression on afatinib monotherapy and the genomic changes that occur through treatment in pts with T pretreated or naïve HER2-positive IBC. Methods: Pts are recruited in 2 parallel cohorts of 20 pts each: T-naïve and T failure. Key eligibility criteria: histologically-confirmed HER2-positive BC; investigator-confirmed IBC characterized by diffuse erythema and oedema (peau d’orange) while dermal lymphatic emboli or palpable mass are not necessary for diagnosis; no prior anti-HER2 therapy except T in the T failure cohort; no prior V; ECOG 0–2. All pts start afatinib monotherapy (40 mg/d oral) in 4-week cycles (Part A). Upon disease progression, pts may receive afatinib (40 mg/d) + V (IV 25 mg/m2/week) (Part B). Primary endpoint: Clinical Benefit Rate (CR, PR or SD) for ≥6 months. Secondary endpoints: objective response rate, PFS, OS and safety. Endpoints are assessed separately for Part A and Part B. Fresh biopsy and blood samples are taken prior to treatment and upon progression in Part A, to explore predictive markers of response/resistance to afatinib, to describe the IBC population which may benefit most, and for next generation sequencing and proteomic analysis. Enrollment ongoing since Aug 2011.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. 4532-4532
Author(s):  
Ramon Jin ◽  
Haeseong Park ◽  
Andrea Wang-Gillam ◽  
Rama Suresh ◽  
Caron E. Rigden ◽  
...  

4532 Background: Standard first-line regimens for patients with metastatic gastroesophageal adenocarcinomas have moderate clinical benefit with objective response rates (ORR) of approximately 40-50%. FOLFIRINOX has been shown to be an effective and well-tolerated first line therapy in other GI cancers. In this open-label, single-arm phase II study of patients with advanced gastroesophageal adenocarcinomas, we sought to evaluate the safety and clinical activity of FOLFIRINOX. Methods: The primary endpoint was ORR, and secondary endpoints included safety profile, progression free survival (PFS), overall survival (OS), time to progression (TTP), clinical benefit rate (CBR), and duration of response. Estimated sample size included 41 patients with HER2 negative disease with 90% power to detect an ORR≥60% with alpha of 0.10. No enrollment goal was planned for HER2 positive patients, but they were allowed participation to receive study treatment in combination with trastuzumab. Treatment consisted of 400mg/m2 5-FU bolus, 400 mg/m2 leucovorin, 2400 mg/m2 5-FU infusion over 46 hours, 180 mg/m2 irinotecan, and 85 mg/m2 oxaliplatin. Trastuzumab was administered intravenously as a 6 mg/kg loading dose then given 4 mg/kg every 14 days for HER2 positive patients. This trial is registered with ClinicalTrials.gov, NCT01928290. Results: From November 2013 to May 2019, 67 patients were enrolled, of which 26 (39%) had HER2 positive disease. Median follow-up was 16.1 months. ORR was 61% (25/41) for HER2 negative and 85% (22/26) for HER2 positive groups. Overall, one patient (2%) had a complete response, 36 patients (69%) had partial responses, and 13 patients (19%) had stable disease for >6 months; therefore, CBR was 96%. Median PFS was 11.9 months, median OS was 17.4 months. 41 patients (83.7%) had dose modification or treatment delay with the most common toxicities being neutropenia, diarrhea, peripheral sensory neuropathy, and nausea with no unexpected toxicities. Conclusions: FOLFIRINOX is a highly effective three-drug regimen for first-line treatment of advanced gastroesophageal cancer with expected, tolerable toxicities. Clinical trial information: NCT01928290 .


2021 ◽  
Vol 39 (3_suppl) ◽  
pp. TPS143-TPS143
Author(s):  
John H. Strickler ◽  
Fang-Shu Ou ◽  
Tanios S. Bekaii-Saab ◽  
Christine Megerdichian Parseghian ◽  
Andrea Cercek ◽  
...  

TPS143 Background: Patients with KRAS and NRAS ( RAS) wild-type mCRC benefit from the epidermal growth factor receptor (EGFR) monoclonal antibodies (Abs) panitumumab and cetuximab, but nearly all patients experience resistance. Blood-based profiling of cell free DNA (cfDNA) can identify genomic alterations that drive acquired EGFR Ab resistance. After discontinuation of anti-EGFR Abs, acquired genomic alterations decay over time to undetectable levels. Some studies have suggested clinical benefit from EGFR Ab rechallenge, but there is limited evidence that EGFR Ab rechallenge improves survival compared to standard of care (SOC) therapies. We hypothesize that cfDNA profiling will identify patients appropriate for panitumumab rechallenge, and that these molecularly selected patients will have improved survival compared to current SOC therapies. Methods: This is a randomized phase II, open label study designed to compare the overall survival (OS) of panitumumab rechallenge versus SOC (investigator choice TAS-102 or regorafenib). Secondary objectives include comparisons of progression free survival, objective response rate, clinical benefit rate, and quality of life as measured by the linear analogue self-assessment (LASA) questionnaire. Eligible patients have radiographically measurable KRAS, NRAS, and BRAF codon 600 wild-type mCRC based on tumor tissue testing, and must have experienced progression or intolerance to treatment with a fluoropyrimidine, oxaliplatin, irinotecan, an anti-VEGF Ab, and an anti-PD-1 Ab if the tumor has mismatch repair deficiency or is MSI-H. Progression after at least 4 months treatment with an anti-EGFR Ab is required. All patients must be enrolled in the COLOMATE cfDNA screening protocol (NCT03765736) and meet molecular eligibility based on Guardant360 cfDNA profiling (absence of amplification of ERBB2, KRAS, NRAS, and MET; absence of mutations of BRAF, EGFR, ERBB2, KRAS, NRAS, and MET [mutant allele frequency > 0.5%]). Greater than 90 days must have elapsed between the most recent treatment with an anti-EGFR Ab and cfDNA profiling. Dosing for all study drugs is according to clinical SOC. 120 patients will be randomized 1:1 to panitumumab rechallenge or SOC. With 83 OS events, this study will have 80% power to detect an improvement in median OS from 6.5 to 10 months (HR=0.65; 1-sided α= 0.15). This study began enrollment in 6/2020. Recruitment is ongoing at 16 sites in the Academic and Community Cancer Research United (ACCRU) network (ACCRU-GI-1623). Clinical trial information: NCT03992456.


2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 1052-1052 ◽  
Author(s):  
A. Chan ◽  
V. Ganju ◽  
D. Becquart ◽  
P. Conte ◽  
L. Petruzelka ◽  
...  

1052 Background: Chemotherapy (CT) plus H is the standard first-line treatment for HER2-positive MBC. H plus vinorelbine is an active and well-tolerated regimen in this setting. The all-oral combination of NVBo and X also appears active and well-tolerated in MBC. We report efficacy and safety results from the first 34 patients (pts) included in an international trial evaluating NVBoXH in HER2-positive MBC. Methods: In this multicenter trial, main eligibility criteria included: HER2-positive disease (IHC 3+ or FISH+), documented measurable MBC previously untreated by CT, relapse 6 months after completing neoadjuvant or adjuvant CT, Karnofsky PS = 70, age =18 years. Pts received 3-weekly cycles of NVBo 60 mg/m2 (cycle 1) escalating to 80 mg/m2 (from cycle 2) days 1 and 8; × 1,000 mg/m2 bid (750 if = 65 years) days 1–14; H 4 mg/kg day 1 as a loading dose then 2 mg/kg i.v. weekly starting on day 8. Treatment was continued until progression or unacceptable toxicity. Primary endpoint is overall response rate. Results: Baseline characteristics: median age 54 years (20% = 65); prior (neo)adjuvant CT 21 pts (62%); type of CT: anthracycline 52%, anthracycline + taxane 29%, CMF 14%, taxane 5%; visceral involvement 29 pts (85%), >2 metastatic sites 13 pts (38%). Treatment administered: median 8 cycles, median relative dose intensity: NVBo 77%, X 81%, H 95%; NVBo dose escalation to 80 mg/m2 in 91% of pts. Safety (n=34, G3/4 NCI CTC v2 adverse events): neutropenia 22 pts (65%), diarrhea 4 pts (12%), febrile neutropenia 3 pts (9%), vomiting 3 pts (9%), hand-foot syndrome 3 pts (9%), asthenia 3 pts (9%), infection without neutropenia 2 pts (6%), LVEF decline 2 pts (6%), stomatitis 1 pt (3%), nausea 1 pt (3%), constipation 1 pt (3%). Efficacy (n=31 evaluable pts): objective response rate (RECIST) 71% (95% CI [52–86]), CR 13%, PR 58%, SD 23%, PD 6%, disease control (CR+PR+ SD for =6 months) 84%. Progression-free survival, overall survival and duration of response data are not yet mature. Conclusions: This is the first trial, in pts with HER2-positive MBC, to show high efficacy with first-line NVBoXH therapy. This regimen can be safely administered in this pt population. No significant financial relationships to disclose.


2009 ◽  
Vol 27 (15_suppl) ◽  
pp. 8074-8074
Author(s):  
E. Tan ◽  
R. Salgia ◽  
B. Besse ◽  
G. Goss ◽  
D. R. Gandara ◽  
...  

8074 Background: ABT-869 is a novel orally active, potent and specific inhibitor of vascular endothelial growth factor and platelet derived growth factor receptor tyrosine kinases. Methods: This ongoing, open-label, randomized, multicenter phase 2 trial of ABT-869 at 0.10 mg/kg daily (Arm A) and 0.25 mg/kg daily (Arm B) until progressive disease (PD) or intolerable toxicity, was initiated to assess antitumor activity and toxicity of ABT-869 in patients (pts) with NSCLC. Eligibility criteria included locally advanced or metastatic NSCLC; ≥ 1 prior systemic treatment, and ≥1 measurable lesion by RECIST criteria. The primary endpoint was the progression free (PF) rate at 16 wks. Secondary endpoints were objective response rate (ORR), time to progression (TTP), progression free survival (PFS) and overall survival (OS). CT scans were assessed by the investigator and centrally; central assessment results are provided. Results: 138 patients (pts) were enrolled from 08/07–10/08 from 27 centers with interim data available for 94 pts (Arm A, n=43; Arm B; n=51). Median age was 64 years and 62 years in Arm A and B respectively. For the interim analysis population (Arm A, n=24; Arm B, n=24), 16 (33.3%) pts were PF at 16 wks: 7 (29.2%) in Arm A and 9 (37.5%) in Arm B. The ORR in Arm A (n=30) was 0% and 7.3% in Arm B (n=41). The median TTP and median PFS were 110 and 109 days, and 112 days and 108 days in Arm A and B, respectively. The most common adverse events (AEs) in Arm A were fatigue (35%), nausea (21%), and anorexia (21%), and in Arm B were hypertension (51%), fatigue (51%), diarrhea (43%), anorexia (41%), nausea (31%), proteinuria (31%) and vomiting (26%). The most common grade 3/4 toxicities in the Arm A were fatigue (7%), ascites (5%), dehydration (5%), pleural effusion (5%), and in the Arm B were hypertension (23%), fatigue (8%), PPE syndrome (8%), dyspnoea (6%) and stomatitis (6%). Most AE's were mild/moderate and reversible with interruptions/dose reduction/or discontinuation of ABT-869. Conclusions: ABT-869 demonstrates an acceptable safety profile and appears to be active in NSCLC patients. [Table: see text]


2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 8587-8587 ◽  
Author(s):  
Joyce Leta Steinberg ◽  
Agop Y. Bedikian ◽  
D. Scott Ernst ◽  
Bartosz Chmielowski ◽  
Bruce Redman ◽  
...  

8587 Background: Survivin is a microtubule-associated protein implicated in both preservation of cell viability and regulation of mitosis in tumor cells. It is over-expressed in melanoma, breast, and non-Hodgkin’s lymphoma. YM155 is a first in class survivin inhibitor. Methods: The study had 2 parts: Part 1 established the dose of docetaxel that was tolerable in combination withYM155 at 5 mg/m2/day continuous infusion over 168 hours q 3 weeks. Part 2 utilized the dose of docetaxel established in Part 1 to further evaluate the tolerability and activity of the combination. The primary endpoint was 6-month progression-free survival (PFS). Secondary endpoints were overall response rate, 1-year overall survival (OS), time from first response to progression, clinical benefit rate, time to response, and safety. Results: 64 patients with metastatic melanoma were treated with docetaxel followed by continuous infusion YM155. 7 patients were treated with 100mg/m2 of docetaxel and 57 patients were treated with 75mg/m2 of docetaxel. Median age was 59, with 44 men and 20 women treated. 6-month PFS per Independent Review Committee (IRC) was 34.8% (95% CI 21.3 – 48.6%). Overall objective response rate per IRC was 12.5%, with no complete responses (CR) and 8 patients with partial responses (PR). The Stable disease (SD) rate was 51.6%, leading to a clinical benefit rate (CR + PR + SD) of 64.1%. Estimated 1-year overall survival is 50.5%. 87.5% of patients experienced a Grade 3 (G3) or Grade 4 (G4) event attributable to either YM155 or docetaxel. The clinically pertinent G3 or 4 toxicities occurring in greater than 5% of patients treated included neutropenia (59.4%), febrile neutropenia (12.5%), mucositis (9.4%), fatigue (7.8%), diarrhea (6.3%), and dehydration (6.3%). There were 3 deaths on study, all attributable to disease progression. Conclusions: YM155 is a novel agent that shows modest activity when combined with docetaxel in patients with melanoma. YM155 was generally well tolerated, but the pre-determined primary endpoint for efficacy was not achieved.


2012 ◽  
Vol 30 (15_suppl) ◽  
pp. TPS651-TPS651 ◽  
Author(s):  
Tamas Hickish ◽  
Ling-Ming Tseng ◽  
Ajay O. Mehta ◽  
Janice Tsang ◽  
Nadezhda Kovalenko ◽  
...  

TPS651 Background: Management of HER2-overexpressing MBC has improved over the past decade. However, pts still develop resistance to currently available HER2-targeted therapies and novel effective treatments are increasingly required as dual targeted combinations are given in early treatment lines already. Current therapies focus on targeting HER2 and do not inhibit all relevant ErbB Family dimers. Afatinib is an oral, irreversible ErbB Family Blocker that inhibits signaling through activated EGFR (ErbB1), HER2 (ErbB2) and ErbB4 receptors and transphosphorylation of ErbB3. Preclinical studies have demonstrated efficacy in T-sensitive and T-resistant human BC xenograft models dependent on ErbB signaling. Efficacy of afatinib in a T-resistant SUM 190 xenograft model has been shown to be increased by addition of IV vinorelbine (V). Afatinib monotherapy has shown promising clinical benefit in 46% of HER2-overexpressing MBC pts who progressed on prior T, with 10% of pts achieving PR. Methods: This open-label Phase II trial (NCT01271725) investigates efficacy and safety of afatinib alone (40 mg/d) followed by afatinib ‘beyond progression’ plus chemotherapy in 120 pts with HER2-overexpressing MBC, who progressed on prior neoadjuvant and/or adjuvant T and/or L. Pts who progress on afatinib monotherapy receive afatinib plus either weekly paclitaxel (P) 80 mg/m2 or V 25 mg/m2. Eligible pts have confirmed HER2-overexpressing BC, stage IV disease measurable by RECIST 1.1, progressed on T and/or L therapy in either neoadjuvant and/or adjuvant setting, are eligible for retreatment with P or V and should not have been pretreated with P (≤12 months) or V, respectively. Exclusion criteria: inadequate cardiac, renal, hepatic and hematological function, pre-existing gastrointestinal dysfunction, rapidly progressing visceral disease, ILD and active brain metastases. The primary endpoint is objective response (OR) and secondary endpoints include best overall response, duration of OR and PFS; safety will be assessed separately for afatinib mono- and combination therapy. Patient enrollment began in May 2011 in ~35 sites and 5 countries.


2012 ◽  
Vol 30 (15_suppl) ◽  
pp. TPS649-TPS649 ◽  
Author(s):  
Nadia Harbeck ◽  
Seock-Ah Im ◽  
Chiun-Sheng Huang ◽  
Young-Hyuck Im ◽  
Binghe Xu ◽  
...  

TPS649 Background: Afatinib is an ErbB Family Blocker that irreversibly blocks signaling from all relevant ErbB Family dimers. Afatinib is being developed in EGFR (ErbB1)-driven (NSCLC/HNSCC) and HER2 (ErbB2)-driven (breast) malignancies. In trastuzumab-resistant, HER2-positive (SUM190) xenografts, afatinib showed antitumor activity which was superior to lapatinib and increased by addition of IV vinorelbine. Afatinib monotherapy also demonstrated clinical activity (progression-free survival [PFS] = 15.1 wk; objective response [OR] = 10%) in an open-label, single-arm, Phase II trial in patients with HER2-positive MBC after progression on trastuzumab. Methods: LUX-Breast 1 (NCT01125566) is a Phase III, open-label, multicenter trial evaluating the efficacy and safety of afatinib + vinorelbine vs. trastuzumab + vinorelbine in patients with HER2-overexpressing MBC who progressed on, or after one prior trastuzumab-based treatment regimen. Patients are randomized 2:1 to afatinib (40 mg/d oral) + vinorelbine (IV 25 mg/m2/wk) or trastuzumab (IV 2 mg/kg/wk after 4 mg/kg loading dose) + vinorelbine (IV 25 mg/m2/wk). Patients receive continuous treatment in the absence of disease progression or adverse events. Key eligibility criteria include histologically-confirmed HER2-positive BC, stage IV disease; no prior treatment with vinorelbine or HER2-targeted treatment other than trastuzumab; progression on one prior trastuzumab based regimen in either the adjuvant (or <12 months after trastuzumab completion) or first-line (or <6 months after trastuzumab completion) setting; prior anthracycline and/or taxane chemotherapy; ECOG score 0 or 1. The primary endpoint is PFS and secondary endpoints include OR, overall survival and safety. Serum and tissue biomarkers will be assessed on archival tissue. HER-receptor and HER-ligand reprogramming, putative resistance markers and EGFR response signature will be explored in fresh tissue biopsies. Enrollment began in June 2010 and is ongoing, targeting >240 sites with a recruitment target of 780 patients.


2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 548-548
Author(s):  
Michael R. Clemens ◽  
Anne Therese Keating ◽  
Oleg Gladkov ◽  
Fei Jie ◽  
Joyce Steinberg ◽  
...  

548 Background: YM155 (YM) is a small molecule survivin suppressant. In a phase I/II study of YM plus docetaxel (D) in solid tumors evidence of anti-tumor activity was observed in women with human epidermal growth factor 2 non-overexpressing (HER2 negative) metastatic breast cancer (mBC). Methods: This was a randomized study of YM plus D versus D as 1st line treatment in subjects with HER2 negative mBC. Eligibility criteria were: ECOG < 1, no prior chemotherapy for mBC, and at least one measurable lesion. Primary endpoint was progression free survival (PFS); secondary endpoints were: objective response rate (ORR), overall survival (OS), duration of response (DOR), clinical benefit rate (CBR), time to response (TTR) and safety. YM was administered at 5 mg/m2/day as a 168 hr continuous infusion followed by 14 Day (d) observation and D was administered at 75 mg/m2over 1 hr on d1 every 21d. In the control arm, D was dosed per investigator choice q 21d. Results: 101 subjects were randomized (50 YM + D; 51 D). Median (m) age 55 (range: 25 – 79), 25% had triple negative disease, > 60% had bone and lymph mets, 86% had prior therapy for BC. mPFS (days) was 251 (95%CI: 176 – 333) YM + D vs 252 (95%CI: 202-433) D (p=0.34). ORR, CBR and TTR (YM+D; D): 26% vs. 25.5%; 82% vs. 84.3% and 45 vs 59 d. OS data are immature but showed no difference (p=0.911). Adverse events [AEs (> 25%)] [YM + D% vs D %]: neutropenia 83 vs 84, alopecia 62.5 vs 53, fatigue 50 vs 41.2, nausea 35.4 vs 41.2, leucopenia 27 vs 33 and dyspnoea 33 vs 14. Common (>10%) serious AEs [YM + D% vs D%]: febrile neutropenia 21 vs 8 and neutropenia 10 vs 8. Conclusions: Preclinical and clinical evidence suggested the combination of YM + D may offer additional benefit to D alone in subjects with mBC. This study showed no difference in efficacy, but the combination appeared to be well tolerated. Clinical trial information: NCT01038804.


2016 ◽  
Vol 34 (4_suppl) ◽  
pp. TPS187-TPS187 ◽  
Author(s):  
Catherine Cafferkey ◽  
Ian Chau ◽  
Fiona Thistlethwaite ◽  
Russell D. Petty ◽  
Naureen Starling ◽  
...  

TPS187 Background: Outcomes for patients with advanced OG cancer remain poor, median overall survival for fit patients treated with platinum and fluoropyrimidine based chemotherapy is less than one year, with second line chemotherapy resulting in a modest (approximately 6 weeks) survival benefit for selected patients. Evidence from NSCLC trials suggests a survival benefit from maintenance treatment following first line chemotherapy. Emerging data also supports the use of immunotherapy in previously treated OG cancer. The PLATFORM study aims to evaluate maintenance therapy in patients with advanced OG cancer. Methods: This is a prospective, open label, multicentre, randomised phase II clinical trial which will recruit at multiple UK cancer centres. Eligible patients are those who have measurable stable disease or better following completion of first line chemotherapy (at least 6 cycles) for locally advanced unresectable or metastatic disease. First line chemotherapy regime should contain a platinum and 5-fluoropyridimine (with trastuzumab if HER2 +), doublet or triplet drug combinations are permitted. Maintenance strategies are split by HER 2 status. For HER2 negative patients these are: Arm A1: surveillance, Arm A2: capecitabine, Arm A3: MEDI 4736 (anti PDL1 inhibitor) and for HER2 positive patients; Arm B1: trastuzumab, Arm B2: in development. Target recruitment is six hundred and sixteen patients, 154 patients will be recruited to each arm, with an interim analysis following recruitment of 61 patients to each arm. An adaptive trial design enables ineffective treatments to be discontinued early, with the opportunity to add novel treatment arms as the trial progresses. Primary endpoint is progression free survival. Secondary endpoints are progression free rate at 3, 6 & 12 months, overall survival, objective response rate by RECIST 1.1, toxicity and analysis of efficacy endpoints according to biomarker status for selected arms. Thirty two patients have been registered for the study with 3 patients randomised, recruitment is ongoing. Clinical trial information: EUDRACT: 2014-002169-30.


2020 ◽  
Vol 38 (15_suppl) ◽  
pp. 1036-1036
Author(s):  
Shanu Modi ◽  
Fabrice Andre ◽  
Ian E. Krop ◽  
Cristina Saura ◽  
Toshinari Yamashita ◽  
...  

1036 Background: Trastuzumab deruxtecan (T-DXd; DS-8201) is an antibody-drug conjugate composed of an anti-HER2 antibody, a cleavable linker, and a cytotoxic topoisomerase I inhibitor. In the pivotal DESTINY-Breast01 trial, efficacy of T-DXd in HER2-positive metastatic breast cancer (mBC) was demonstrated, with an objective response rate (ORR) of 60.9% and median progression-free survival (mPFS) of 16.4 months. Methods: DESTINY-Breast01 was a single-group, open-label, multicenter, phase II trial of 184 patients with HER2-positive mBC previously treated with trastuzumab emtansine (T-DM1) who received T-DXd at 5.4 mg/kg. Multivariate analysis using logistic regression models (ORR) and Cox proportional hazards models (duration of response [DOR], mPFS) explored 15 relevant clinical predictor variables. Circulating tumor DNA (ctDNA) was collected prior to the first dose, every 3 cycles of treatment, and at the end of treatment. Sequencing was done via GuardantOMNI (Guardant Health) for single-nucleotide variation/insertion and deletion, amplification, and fusion of ≈ 500 genes. Results: Efficacy in all evaluated clinical subgroups was similar to the overall ORR 60.9% and mPFS 16.4 months with ranges from ORR 46.4%-74.5% and mPFS 12.3-18.1 months. Variables associated with improved ORR, DOR, or mPFS included hormone receptor positive status, fewer prior treatment regimens (continuous variable), pertuzumab given in the first or second line, and normal renal and hepatic function. Variables that did not impact efficacy outcomes compared to the overall population include age, race, region, ECOG PS, HER2 IHC 3+ status, progesterone receptor status, best response to T-DM1, time since diagnosis, and history of brain metastases. In 48 subjects with progression as of data cut date, metastases were most commonly observed in the liver, lung, and lymph nodes. Only 8% (4 of 48) had progression involvement in the brain upon disease progression. Decrease of ERBB2 copy number in ctDNA was seen on treatment and correlated with clinical response. Additional changes in molecular markers on treatment and following progression will be described. Conclusions: T-DXd demonstrated strong efficacy in all clinical subgroups analyzed. Further exploration of both clinical and molecular variables to determine biomarkers of efficacy may be warranted. Clinical trial information: NCT03248492 .


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