The HORIZON III retrospective exploratory analysis: HER2 expression amplification in colorectal cancer

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Background: Although regularly used in breast and gastric cancer, HER2 testing is not routinely performed in colorectal cancer (CRC). Immunohistochemistry (IHC) and in situ hybridization (ISH) scoring have not been optimized for assessment of HER2 overexpression and amplification in CRC. Varying rates of HER2 overexpression (2%-11%) have been reported in previously untreated CRC (Wang World J Gastrointest Oncol 2019) and patients with advanced/metastatic CRC with HER2 amplification or overexpression respond poorly to current standard of care therapies (Sartore-Bianchi Oncologist 2019). We characterized HER2 prevalence in a retrospective cohort analysis of clinical trial patients. Methods: The HORIZON III trial (NCT00384176) evaluated FOLFOX + bevacizumab or cediranib (AZD2171) as first-line (1L) treatment in patients with metastatic CRC (Schmoll J Clin Oncol 2012). The primary objective of this analysis of a subset of HORIZON III samples was to characterize HER2 prevalence in 1L metastatic CRC. Secondary and exploratory objectives included correlating HER2 status to other molecular findings (eg, RAS/RAF mutations), clinicopathologic characteristics, and patient outcomes. IHC was performed using a monoclonal anti-HER2 antibody PATHWAY HER2 [4B5] Ventana on primary CRC tumor sections and scored according to ASCO/CAP guidelines for gastric cancer (Bartley Arch Pathol Lab Med 2016). H&E staining was performed to determine the adequacy of tumor samples (ie, > 100 viable tumor cells per specimen). All tumors with an IHC score of 2+ were analyzed for amplification by ISH (HER2 IQFISH pharmDx dual probe kit, Agilent Technologies K573111-5). Targeted mutation panel testing was used to determine other molecular alterations. Descriptive statistics were used to summarize baseline and clinical outcome data by HER2 status. The current analysis was approved by the AstraZeneca bioethics review board. Results: Of the 1614 patients in HORIZON III, 396 met the inclusion criteria of appropriate consent, sufficient tumor sample for analysis, and a unique identifier. HER2-positive tumors (IHC3+ or IHC2+/ISH+) were identified in 2.1% of samples; 1.3% were IHC3+ and 0.8% were IHC2+/ISH+. Compared with IHC3+, IHC2+ tumors were more heterogeneous with mixed components of cells weakly expressing HER2 and lacking HER2 expression. Conclusions: This exploratory analysis of the HORIZON III study provides insights into HER2 prevalence in 1L, unselected, advanced/metastatic CRC, finding that 2.1% of tumors were HER2 positive. The demographic characteristics of patients with analyzable samples were representative of the entire HORIZON III study population; however, further assessment of KRAS status and other clinicopathological characteristics is needed. These data may inform future clinical development and support selection of patients with CRC who are likely to benefit from HER2 targeting therapies. Clinical trial information: NCT00384176 .

Abstract CT572: Phase 1b dose-escalation and dose-expansion study evaluating trastuzumab deruxtecan (T-DXd) in combination with durvalumab and cisplatin, carboplatin, or pemetrexed in advanced or metastatic, HER2-overexpressing, nonsquamous non-small cell lung cancer (NSCLC): DESTINY-Lung03

Background: HER2 overexpression is an established molecular target in breast and gastric cancer therapy, but no HER2-targeted therapies are currently available for NSCLC. In studies of NSCLC and lung cancer overall, the prevalence of HER2 overexpression has been reported to be anywhere from <5% to 35% (Cox et al. Int J Cancer. 2001;92:480-483; Hirsch et al. Lancet. 2017;389:299-311). T-DXd is an antibody-drug conjugate composed of a humanized anti-HER2 monoclonal antibody, a tetrapeptide-based cleavable linker, and a topoisomerase I inhibitor payload. Interim results from the DESTINY-Lung01 trial showed encouraging efficacy in extensively pretreated patients (pts) with unresectable/metastatic, HER2-overexpressing, nonsquamous NSCLC, with a confirmed objective response rate (ORR) of 24.5% and median overall survival (OS) of 11.3 months (Nakagawa et al. WCLC 2020. Abstract OA04.05). Preclinically, the combination of T-DXd and an anti-programmed cell death 1 antibody was more effective than either therapy alone. The DESTINY-Lung03 trial is evaluating the safety and tolerability of T-DXd in combination with durvalumab and chemotherapy in pts with unresectable/metastatic, HER2-overexpressing, nonsquamous NSCLC.

Methods: DESTINY-Lung03 (NCT04686305) is a phase 1b, open-label, multicenter, dose-escalation (part 1) and dose-expansion (part 2) study in pts with HER2-overexpressing (≥25% immunohistochemistry 2+/3+ tumor cells), unresectable, locally advanced or metastatic, nonsquamous NSCLC. In part 1, pts with progression after 1 or 2 lines of systemic therapy in the recurrent/metastatic setting are enrolled to receive T-DXd and durvalumab in combination with cisplatin (arm 1A), carboplatin (arm 1B), or pemetrexed (arm 1C), or T-DXd monotherapy (arm 1D). In part 2, pts who have not received prior curative treatment in the locally advanced setting or systemic treatment in the metastatic setting are enrolled to receive T-DXd and durvalumab in combination with cisplatin (arm 2A), carboplatin (arm 2B), or pemetrexed (arm 2C), or T-DXd plus durvalumab (arm 2D); pts in part 2 must not have activating EGFR mutations, an EML4-ALK fusion, or other targetable alterations. The primary endpoint is the frequency of adverse events (AEs) and serious AEs (SAEs) with T-DXd plus durvalumab plus chemotherapy combinations to assess safety and tolerability and determine the recommended phase 2 dose. Secondary endpoints include confirmed ORR, duration of response, disease control rate, progression-free survival, OS, frequency of AEs and SAEs with T-DXd monotherapy (part 1) and T-DXd plus durvalumab (part 2), pharmacokinetics, and immunogenicity.

Citation Format: David Planchard, Julie R. Brahmer, James C. Yang, Yuh-Min Chen, Kang-Yun Lee, Thatthan Suksombooncharoen, Natasha Viglianti, Mark Gustavson, Alejandra Ragone, Amaya Gasco Hernandez. Phase 1b dose-escalation and dose-expansion study evaluating trastuzumab deruxtecan (T-DXd) in combination with durvalumab and cisplatin, carboplatin, or pemetrexed in advanced or metastatic, HER2-overexpressing, nonsquamous non-small cell lung cancer (NSCLC): DESTINY-Lung03 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT572.

Open-label, randomized, multicenter, phase 3 study evaluating trastuzumab deruxtecan (T-DXd) as first-line treatment in patients with unresectable, locally advanced, or metastatic non–small cell lung cancer (NSCLC) harboring HER2 exon 19 or 20 mutations (DESTINY-Lung04)

TPS9137

Background: The standard of care (SOC) for patients with oncogene driver subsets of metastatic NSCLC is guided by specific molecular characterization and includes immunotherapy, chemoimmunotherapy, and matched targeted therapies. Although targeting HER2 has transformed the care of patients with breast and gastric cancers, there is currently no approved HER2-targeted therapy for NSCLC. T-DXd is an antibody-drug conjugate consisting of an anti-HER2 antibody, a cleavable tetrapeptide-based linker, and a topoisomerase I inhibitor payload. In a cohort of pretreated patients (median, 2 prior lines) with unresectable or metastatic HER2-mutant NSCLC, T-DXd demonstrated durable and robust anticancer activity, with a confirmed objective response rate (ORR) of 55% and median duration of response (DOR), progression-free survival (PFS), and overall survival (OS) of 9.3, 8.2, and 17.8 months, respectively (Li et al. N Engl J Med. 2022). Given the efficacy observed in later-line settings and the unmet need for targeted therapies in patients with HER2-mutant NSCLC, evaluating the efficacy of T-DXd in the first-line setting vs SOC is important to determine the optimal treatment. Here we describe the phase 3 DESTINY-Lung04 trial (NCT05048797) evaluating T-DXd as a first-line treatment in patients with NSCLC harboring HER2 mutations. Methods: DESTINY-Lung04 is an open-label, randomized, multicenter, phase 3 study evaluating the efficacy and safety of first-line T-DXd vs SOC in patients with unresectable, locally advanced (not amenable to curative therapy), or metastatic nonsquamous NSCLC with HER2 exon 19 or 20 mutations (detected in tissue or circulating tumor DNA). Patients must be naive to systemic therapy with palliative intent in the locally advanced or metastatic disease setting and must not have tumors with EGFR or other targetable oncogenic alterations. Patients with brain metastases must have previously completed local therapy. Patients will be randomized to receive T-DXd or SOC (platinum [investigator’s choice of cisplatin or carboplatin], pemetrexed, and pembrolizumab). The primary endpoint is PFS defined by RECIST version 1.1 per blinded independent central review (BICR). Secondary endpoints include OS, ORR, and DOR (by RECIST 1.1 per BICR and investigator), investigator-assessed PFS (by RECIST 1.1) and time to second progression or death (per local standard clinical practice), central nervous system PFS (by RECIST 1.1 per BICR), landmark PFS at 12 months (by RECIST 1.1 per BICR and investigator), and landmark OS at 24 months. Safety and tolerability, pharmacokinetics, immunogenicity, and patient-reported outcomes, including pulmonary symptoms and tolerability, will be assessed. Clinical trial information: NCT05048797.

A phase Ib/II, multicenter, open-label, dose-escalation, and dose-expansion study evaluating trastuzumab deruxtecan (T-DXd, DS-8201) monotherapy and combinations in patients with HER2-overexpressing gastric cancer (DESTINY-Gastric03)

TPS261

Background: For patients (pts) with HER2-overexpressing metastatic gastric cancer, trastuzumab + chemotherapy is a standard first-line option but provides only a modest overall survival (OS) benefit vs chemotherapy. T-DXd is an antibody-drug conjugate consisting of an anti-HER2 antibody, cleavable tetrapeptide-based linker, and a membrane-permeable topoisomerase I inhibitor payload. Results from a phase 1 trial showed promising antitumor activity (confirmed objective response rate [ORR], 43.2%) in pts with heavily pretreated HER2+ metastatic gastric cancer who received T-DXd (5.4 or 6.4 mg/kg; Shitara K, et al. Lancet Oncol. 2019;20:827-836). Here we describe the phase 1b/2 DESTINY-Gastric03 trial (NCT04379596) evaluating T-DXd monotherapy and combinations in pts with HER2-overexpressing gastric cancer. Methods: This is an open-label, multicenter, 2-part, phase 1b/2 study in pts with HER2-overexpressing (immunohistochemistry [IHC] 3+ or IHC 2+/in situ hybridization positive) locally advanced, unresectable or metastatic gastric or gastroesophageal junction cancer. In part 1 (dose escalation), pts who had received prior trastuzumab-containing therapy will be assigned to 1 of 5 arms: (1) T-DXd + 5-fluorouracil (5-FU); (2) T-DXd + capecitabine (C); (3) T-DXd + durvalumab; (4) T-DXd + 5-FU or C + oxaliplatin (Ox); or (5) T-DXd + 5-FU or C + durvalumab. In part 2 (dose expansion), pts with no prior treatment for metastatic disease will be randomized across 4 arms: (1) T-DXd; (2) trastuzumab + 5-FU or C + Ox or cisplatin; (3) T-DXd + 5-FU or C ± Ox; or (4) T-DXd + 5-FU or C + durvalumab. In part 2, pts will be stratified by HER2 status. Primary endpoints are safety, determination of recommended phase 2 doses (part 1), and investigator-assessed confirmed ORR per RECIST v1.1 (part 2). Secondary endpoints include confirmed ORR (part 1), disease control rate, duration of response, progression-free survival (all per investigator), OS, safety (part 2), pharmacokinetics, and immunogenicity. Clinical trial information: NCT04379596.