Melissa Manoogian

Abstract Outcomes for patients with advanced hepatocellular carcinoma (HCC) remain poor despite recent progress in drug development. Emerging data implicate FGF19 as a potential HCC driver, suggesting its receptor, FGFR4, as a novel therapeutic target. We evaluated fisogatinib (BLU-554), a highly potent and selective oral FGFR4 inhibitor, in a phase I dose-escalation/dose-expansion study in advanced HCC using FGF19 expression measured by IHC as a biomarker for pathway activation. For dose escalation, 25 patients received 140 to 900 mg fisogatinib once daily; the maximum tolerated dose (600 mg once daily) was expanded in 81 patients. Fisogatinib was well tolerated; most adverse events were manageable, grade 1/2 gastrointestinal events, primarily diarrhea, nausea, and vomiting. Across doses, the overall response rate was 17% in FGF19-positive patients [median duration of response: 5.3 months (95% CI, 3.7–not reached)] and 0% in FGF19-negative patients. These results validate FGFR4 as a targetable driver in FGF19-positive advanced HCC. Significance: Fisogatinib elicited clinical responses in patients with tumor FGF19 overexpression in advanced HCC. These results validate the oncogenic driver role of the FGFR4 pathway in HCC and the use of FGF19 as a biomarker for patient selection. See related commentary by Subbiah and Pal, p. 1646. This article is highlighted in the In This Issue feature, p. 1631

“Environmental Health Literacy” (EHL) is embraced as important for improving public health by preventing disability and disease from our environment. This study aimed to determine knowledge and skill items identified by Environmental Health (EH) professionals as being associated with EHL and to understand how these items rank by importance. Such a coordinated effort to tease out skills and knowledge needed for EHL had not previously been made. We utilized a mixed-methods approach of semi-structured interviews of 24 EH professionals and a quantitative survey with 275 EH professionals across the United States. Interviews identified 37 skill and 69 knowledge items, which were used to create the survey questions. Survey results indicate 32 knowledge items and six skill items considered essential by >50% of respondents where consensus was reached between professional groups (chi square test: p > 0.05). We further identified six knowledge items, which >70% of EH professionals agreed were essential for EHL. The identification of these knowledge and skill items sets the stage for further research that includes exploring agreement with more diverse stakeholders, developing comprehensive measures of EHL and evaluation of methods and materials designed to improve EHL.

In DESTINY-Breast04 (DB-04), safety and efficacy of HER2-targeted antibody-drug conjugate (ADC) trastuzumab deruxtecan (T-DXd) in previously treated HER2-low unresectable/metastatic breast cancer were established. This manuscript describes the analytical validation of PATHWAY Anti-HER2/neu (4B5) Rabbit Monoclonal Primary Antibody (PATHWAY HER2 (4B5)) to assess HER2-low status and its clinical performance in DB-04. Preanalytical processing and tissue staining parameters were evaluated to determine their impact on HER2 scoring. The recommended antibody staining procedure provided the optimal tumor staining, and deviations in cell conditioning and/or antibody incubation times resulted in unacceptable negative control staining and/or HER2-low status changes. Comparisons between antibody lots, kit lots, instruments, and day-to-day runs showed overall percent agreements (OPAs) exceeding 97.9%. Inter-laboratory reproducibility showed OPAs of ≥97.4% for all study endpoints. PATHWAY HER2 (4B5) was utilized in DB-04 for patient selection using 1340 tumor samples (59.0% metastatic, 40.7% primary, (0.3% missing data); 74.3% biopsy, 25.7% resection/excisions). Overall, 77.6% (823/1060) of samples were HER2-low by both central and local testing, with the level of concordance differing by sample region of origin and collection date. In DB-04, the efficacy of T-DXd over chemotherapy of physician's choice was consistent, regardless of the characteristics of the sample used (primary or metastatic, archival, or newly collected, biopsy or excision/resection). These results demonstrate that PATHWAY HER2 (4B5) is precise and reproducible for scoring HER2-low status and can be used with multiple breast cancer sample types for reliably identifying patients whose tumors have HER2-low expression and are likely to derive clinical benefit from T-DXd.

BACKGROUND: The DESTINY-Breast06 study demonstrated a statistically significant and clinically meaningful improvement in progression-free survival benefit with trastuzumab deruxtecan (T-DXd) versus chemotherapy treatment of physician's choice in patients with hormone receptor-positive metastatic breast cancer (mBC) whose tumors were scored as human epidermal growth factor receptor 2 (HER2)-low [immunohistochemistry (IHC) 1+, or IHC 2+/in situ hybridization (ISH)-negative] and who had received one or more lines of endocrine therapy and no previous chemotherapy in the metastatic setting. An exploratory analysis consistently showed a benefit for patients with HER2-low and HER2-ultralow (IHC 0 with membrane staining) expression. MATERIALS AND METHODS: Analytical validation of the PATHWAY HER2 (4B5) assay (Roche HER2 4B5 assay; Roche Diagnostic Solutions) at the HER2-ultralow cut-off was carried out, including intermediate precision, inter-reader precision, and inter-laboratory reproducibility. Patients with tumors historically classified as HER2-negative (IHC 0, 1+, and 2+/ISH-negative) based on pre-existing local test results were eligible for screening for DESTINY-Breast06; tumor samples taken in the metastatic setting were assessed centrally to confirm eligibility regarding HER2 status. Additionally, central and pre-existing HER2 test results were compared, and the prevalence of IHC scores based on central test results was assessed. RESULTS: Intermediate precision met the pre-specified endpoints across all parameters tested; agreement was observed within and between readers and sites, demonstrating that the HER2-ultralow cut-off can be scored accurately and reproducibly using the Roche HER2 4B5 assay (intra- and inter-laboratory and inter-reader agreement ≥95%). A clinically meaningful progression-free survival (hazard ratios 0.43-0.78) and objective response rate (odds ratios 2.5-4.5) improvement for T-DXd over chemotherapy was consistently observed across IHC expression levels. For cases with a pre-existing HER2 IHC 0 result, central testing found 24% with HER2-low, 40% with IHC 0 with membrane staining, and 35% with IHC 0 absent membrane staining. CONCLUSIONS: For patients with HER2 IHC 0 mBC, rescoring and/or retesting with the Roche HER2 4B5 assay is encouraged to determine eligibility for T-DXd.

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