On January 8, 2026 Astellas Pharma U.S., Inc. (Head of US Commercial: Mike Petroutsas, "Astellas") reported the publication of exploratory ad hoc analyses from the combined Phase 3 SPOTLIGHT (NCT03504397) and GLOW (NCT03653507) studies in patients with HER2-negative, CLDN18.2-positive advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma in ESMO (Free ESMO Whitepaper) Open, characterizing the management of adverse events on treatment adherence and efficacy of VYLOY (zolbetuximab) plus chemotherapy and evaluating strategies for managing these side effects.
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The exploratory analyses, which included 1,072 patients, reported higher mPFS and mOS estimates for patients treated with zolbetuximab plus chemotherapy after censoring data from patients who discontinued early or had inadequate treatment exposure due to nausea and/or vomiting.1
Pooled data from the analyses show that mPFS with zolbetuximab plus chemotherapy was 10.4 months (95% confidence interval [CI]: 8.8-12.2), and 8.2 months (95% CI: 7.7-8.4) with placebo plus chemotherapy. The hazard ratio [HR] versus placebo was 0.65 (95% CI: 0.56-0.76).1
Similarly, mOS with zolbetuximab plus chemotherapy was 17.9 months (95% CI: 16.4-19.5) and 13.7 months (95% CI: 12.4-15.3) with placebo plus chemotherapy with a HR versus placebo of 0.69 (95% CI: 0.60-0.80).1
Sam Klempner, MD, Gastrointestinal Medical Oncologist, Massachusetts General Hospital, Boston:
"Nausea and vomiting are important symptoms that can affect patient comfort and treatment continuity for advanced gastric or GEJ cancer, particularly during early cycles when these symptoms are most common. Supportive care measures are therefore an important part of managing patients receiving cancer therapy."
Zolbetuximab (VYLOY) is an FDA approved monoclonal antibody for patients with HER2-negative, CLDN18.2-positive advanced gastric or GEJ cancer. In combination with chemotherapy, zolbetuximab demonstrated statistically significant improvements in PFS and OS compared with placebo plus chemotherapy in the SPOTLIGHT and GLOW Phase 3 clinical trials.2,3 In SPOTLIGHT and GLOW, the incidence of serious treatment emergent adverse events (TEAEs) was similar in the zolbetuximab treatment groups compared with placebo plus chemotherapy. The most common all-grade TEAEs reported in the zolbetuximab treatment groups were nausea, vomiting and decreased appetite.2,3
The ad-hoc analyses in these studies showed an association between nausea and vomiting and higher treatment discontinuation rates compared with placebo.
Timothy Forrest, RN, BSN, Massachusetts General Hospital, Boston:
"Early cycles are a critical window for supporting patients starting treatment for advanced gastric or GEJ cancer. Since we know nausea and vomiting are common in this setting, preparing patients, monitoring closely, and using guideline-aligned supportive care can make a meaningful difference to their comfort and ability to continue treatment as planned."
Within the published exploratory analyses, the effect of guideline-aligned supportive care on early nausea and vomiting associated with zolbetuximab plus chemotherapy was assessed.1 Data indicate that use of a guideline-recommended three-drug antiemetic regimen was associated with a higher proportion of patients who did not experience nausea or vomiting at cycle 1 dose 1 (C1D1; 60.8% and 75.3%, respectively).1
Additionally, across the SPOTLIGHT and GLOW trials, 57.9% of patients who received steroids at C1D1 did not experience nausea (versus 49.7% without steroids) and 63.7% did not experience vomiting at C1D1 (versus 62.6% with no steroids).1
Finally, results from the combined analysis suggest that a faster initial infusion may have contributed to adverse events such as nausea and vomiting observed during the first infusion. The authors noted that infusion-rate modifications may help mitigate these symptoms.1
Exploratory ad hoc analyses are hypothesis generating, and further work investigating the clinical validity of these results would be of value.
Astellas is committed to supporting patients and the oncology care community by continuing to generate insights that enhance the patient and healthcare professional experience and better understand supportive care needs and treatment experiences.
About the SPOTLIGHT Phase 3 Clinical Trial
SPOTLIGHT is a Phase 3, global, multi-center, double-blind, randomized study assessing the efficacy and safety of zolbetuximab plus mFOLFOX6 (a combination chemotherapy regimen that includes oxaliplatin, leucovorin, and fluorouracil) compared to placebo plus mFOLFOX6 as a first-line treatment in patients with locally advanced, unresectable or metastatic HER2-negative gastric or GEJ adenocarcinoma whose tumors were CLDN18.2 positive. The study enrolled 565 patients at 215 study locations in the U.S., Canada, United Kingdom, Australia, Europe, South America, and Asia. The primary endpoint was progression-free survival (PFS) of participants treated with the combination of zolbetuximab plus mFOLFOX6 compared to those treated with placebo plus mFOLFOX6. Secondary endpoints included overall survival (OS), objective response rate (ORR), duration of response (DOR), safety and tolerability, and quality-of-life parameters.
Data from the SPOTLIGHT clinical trial were presented during the 2023 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Gastrointestinal (GI) Cancers Symposium in an oral presentation on January 19, 2023, and were subsequently published in The Lancet on April 14, 2023. The final analyses of SPOTLIGHT and GLOW, including additional supporting data in the appendix, were later published as a Letter to the Editor in the New England Journal of Medicine in 2024.
For more information, please visit clinicaltrials.gov under Identifier NCT03504397.
About the GLOW Phase 3 Clinical Trial
GLOW is a Phase 3, global, multi-center, double-blind, randomized study assessing the efficacy and safety of zolbetuximab plus CAPOX (a combination chemotherapy regimen that includes capecitabine and oxaliplatin) compared to placebo plus CAPOX as a first-line treatment in patients with locally advanced unresectable or metastatic HER2-negative gastric or GEJ adenocarcinoma whose tumors were CLDN18.2 positive. The study enrolled 507 patients at 166 study locations in the U.S., Canada, United Kingdom, Europe, South America, and Asia, including Japan. The primary endpoint was PFS in participants treated with the combination of zolbetuximab plus CAPOX compared to those treated with placebo plus CAPOX. Secondary endpoints included OS, ORR, DOR, safety and tolerability, and quality-of-life parameters.
Data from the GLOW study were initially presented at the March 2023 ASCO (Free ASCO Whitepaper) Plenary Series with an updated oral presentation at the 2023 ASCO (Free ASCO Whitepaper) Annual Meeting on June 3, 2023, and were subsequently published in Nature Medicine on July 31, 2023.
For more information, please visit clinicaltrials.gov under Identifier NCT03653507.
About VYLOY
VYLOY (zolbetuximab) is a monoclonal antibody (mAb) specifically designed to target tumor cells that express claudin 18.2 (CLDN18.2), a transmembrane protein. By binding to CLDN18.2, zolbetuximab induces cancer cell death and inhibits tumor growth by activating two distinct immune system pathways – antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC), as demonstrated in preclinical studies.
In both the SPOTLIGHT and GLOW Phase 3 clinical trials, approximately 38% of patients screened had tumors that were CLDN18.2 positive, defined as ≥75% of tumor cells demonstrating moderate to strong membranous CLDN18.2 immunohistochemical staining.
Astellas collaborated with Roche on the Ventana CLDN18 (43-14a) RXDX assay which, where approved, can be used by pathologists or laboratories to identify patients eligible for targeted treatment with zolbetuximab.
(Press release, Astellas, JAN 8, 2026, View Source [SID1234661868])