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TRIPLEX — Thoracic radiotherapy added to durvalumab + platinum/etoposide, 1L ES-SCLC

Abstract: LBA8005 · Session: Lung Cancer — Late-Breaking Oral Abstract (8000-series, lung track), 2026 ASCO Annual Meeting · Presenter: Åslaug Helland, MD, PhD, Oslo University Hospital · Embargo: lifts on day of presentation

At a glance

  • Sponsor: Norwegian University of Science and Technology (NTNU) — investigator-initiated, Nordic cooperative (not French; the IFCT label sometimes attached to "TRIPLEX" is a mismatch — this is the NTNU/Helland–Grønberg Nordic trial)
  • PI / presenter: Åslaug Helland (Oslo University Hospital); Bjørn Henning Grønberg (NTNU) trial group
  • NCT ID: NCT05223647
  • Phase: 3
  • Design: Randomized open-label. Experimental arm = carboplatin/etoposide + durvalumab plus thoracic radiotherapy 30 Gy/10 fractions delivered between cycles 2 and 3, then durvalumab maintenance. Control arm = carboplatin/etoposide + durvalumab → durvalumab maintenance (CASPIAN-style backbone).
  • N: 239 (actual enrollment)
  • Primary endpoint(s): Overall survival (change in 1-year OS; Cox PH, evaluated ~14 months post-enrollment)
  • Comparator: chemo-immunotherapy alone (active control)
  • Indication: extensive-stage small-cell lung cancer (ES-SCLC)
  • Line: first-line
  • Geography: Norway, Sweden, Iceland, Estonia, Netherlands

Headline result

The trial was terminated early on the advice of its Data Safety Committee due to excess toxicity in the experimental (added thoracic radiotherapy) arm (ClinicalTrials.gov, status verified Jan 2026). The LBA8005 presentation reports outcomes from the 239 randomized patients. Detailed efficacy results — OS hazard ratio, p-value, and median OS by arm — were under embargo and not publicly available at the time of writing; numbers are not reproduced here to avoid fabrication. The load-bearing, sourced finding to date is the safety-driven early stop: adding concurrent/interleaved thoracic radiotherapy (30 Gy/10 fx between cycles 2–3) to first-line carboplatin/etoposide + durvalumab was not deliverable at an acceptable toxicity threshold in this design.

Mechanism / class

Durvalumab is an anti–PD-L1 monoclonal antibody; the chemo-IO backbone (platinum/etoposide + durvalumab) is the CASPIAN-derived 1L ES-SCLC standard. The trial's hypothesis was that thoracic radiotherapy added to chemo-IO would improve OS via local control and radiation-induced immunogenic priming of checkpoint blockade — the same rationale validated by ADRIATIC (consolidation durvalumab after chemoRT) in limited-stage SCLC, extended here to extensive-stage with radiotherapy interleaved early during induction.

Practice-changing?

No (negative / cautionary). An early termination for excess toxicity argues against routinely interleaving 30 Gy/10 fx thoracic radiotherapy between induction cycles of chemo-IO in ES-SCLC. The result reframes the consolidative-TRT question (RTOG/CREST-era and ongoing trials) and the SAKK 15/19 sequencing approach (TRT after chemo-IO) as the safer scheduling paradigm. Pending the embargoed OS data, the practical takeaway is that timing/schedule of TRT in the IO era matters and concurrent-with-induction is poorly tolerated.

Sources