Daiichi Sankyo’s ifinatamab deruxtecan (I-Dxd) has triggered clinically meaningful responses in a mid-phase extensive-stage small cell lung cancer (ES-SCLC) trial.
During the Phase II IDeate-Lung-01 study (NCT05280470), the B7 homolog 3 (B7-H3) directed antibody-drug conjugate (ADC) triggered an objective response rate (ORR) of 48.2% in pre-treated patients.
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By GlobalDataThree (2.2%) out of 137 patients experienced a complete response (CR) with I-Dxd treatment, while 63 (46%) had partial responses (PR) to treatment. 54 cases of stable disease were observed.
The median duration of response (DOR) to treatment in the full ES-SCLC patient population was 5.3 months, with I-Dxd exhibiting a disease control rate of 87.6%. Median overall survival (OS) of the 137-patient cohort was 10.3 months.
However, a patient subset analysis revealed that patients receiving I-Dxd as a second-line treatment obtained the largest benefit from the ADC, with 56.3% of patients experiencing ORR. This population experienced a median DOR rate of 7.2 months, while the median OS value was 12 months.
Though the safety profile of I-Dxd was consistent with Phase I findings, 36.5% of patients in the study experienced severe treatment-related adverse events (TRAEs) classed Grade 3 or higher. There were also two deaths associated with I-Dxd, triggered by treatment-associated interstitial lung disease/pneumonitis.
Individuals enrolled on this study had been treated with at least one line of platinum-based chemotherapy, but a majority had been treated with two prior lines of systemic therapy.
Daiichi Sankyo presented the data in a late-breaking session at the 2025 World Conference on Lung Cancer (WCLC) hosted by the International Association for the Study of Lung Cancer (IASLC) in Barcelona, Spain.
I-Dxd’s market potential
If given the green light, I-Dxd would be the first B7-H3 ADC to market in this indication, which is currently fraught with unmet needs despite the availability of standard of care (SoC) treatments.
Upon its potential US Food and Drug Administration (FDA) approval, it would go head-to-head with Jazz Pharmaceuticals’ Zepzelca (lurbinectedin), which obtained accelerated approval in 2020. This regulatory go-ahead made it the first drug to be approved in the post-platinum setting for more than two decades after topotecan’s market debut in 1998.
However, the dominance of Zepzelca and topotecan in this patient population is currently under threat by Amgen’s Imdelltra (taralatamab), which received accelerated approval for second-line ES-SCLC in May 2024 based on the results of the DeLLphi-301 trial (NCT05060016).
If approved, I-Dxd could threaten the market share of Imdelltra, as its ORR of 48% observed in the IDeate-Lung-01 study is 8% higher than the ORR observed in the Phase II trial of the T-cell engager (TCE).
Analysts at GlobalData – parent company of Clinical Trials Arena – forecast that I-Dxd could become a blockbuster drug by 2031, raking in just over $1bn for Daiichi Sankyo if it were to gain approval.
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