Deals

Astra’s Datroway biomarker gives and it takes away

29 April 2026

The QCS assay for TROP2 is being implemented more broadly, at the cost of further readout delays.

AstraZeneca has made much of its development of an assay for the elusive TROP2 biomarker, and it’s evident from Wednesday’s first-quarter update that this is now being implemented across several key studies of its Daiichi Sankyo-partnered anti-TROP2 ADC Datroway.Still, this has come at a cost, with delays to the readouts of two more Datroway trials, Tropion-Lung07 and 08, being ascribed to the recent inclusion of this QCS (quantitative continuous scoring) assay. These come after the readout of Avanzar, the first pivotal Datroway study to explore the utility of the TROP2 test, was delayed twice.The good news is that Avanzar is still expected to yield data in the second half of this year, Astra said on Wednesday. Avanzar, testing Datroway plus Infinzi and chemo in first-line NSCLC, has a complex design, with primary endpoints comprising PFS and OS in TROP2-positive non-squamous patients, and PFS and OS in biomarker-undefined non-squames.TROP2 secret sauceA tumour’s TROP2 expression is thought to be difficult to analyse, but enriching for this biomarker could be essential to dialling up the efficacy of TROP2-targeting molecules, which has so far rather underwhelmed.Astra’s in-house QCS diagnostic was developed specifically for the TROP2 biomarker, and the company says it gauges the internalisation of an antibody inside the cell. TROP2 positivity is then expressed as a normalised membrane ratio (NMR), a measure of TROP2 expression in the membrane relative to the cytoplasm of tumour cells.In addition to Avanzar, the QCS assay is now being used in Tropion-Lung08, another first-line NSCLC study, into which PFS and OS in the TROP2 NMR-positive population have been added as key secondary endpoints. This change has yet to be reflected in clinicaltrials.gov, but was disclosed in Astra’s first-quarter presentation.In a similar way Astra/Daiichi in January added PFS and OS in TROP2 NMR-positive patients, this time as new co-primaries, to the endpoints of Tropion-Lung07. However, Tropion-07 and 08 were earlier due to yield data in the first half of 2026, but readout has recently slipped into 2027, Astra confirmed.In a note to clients, Jefferies analysts attributed these delays specifically to the inclusion of the QCS biomarker into studies, and ApexOnco understands that this is accurate. However, it’s not clear what in particular – physician adoption, ease of use or time taken to generate the biomarker data, for instance – is causing such delays. Phase 3 Datroway trials that use the QCS assay for TROP2StudySettingRegimenPrimary endpointsTimelineAvanzar1st-line NSCLC+ Imfinzi + chemo, vs Keytruda + chemoPFS & OS in TROP2+ve non-sq; PFS & OS in all non-sqData due H2 2026 (prev H2 2025)Tropion-Lung071st-line non-sq NSCLC (PD-L1<50%)+ Keytruda +/- chemo, vs Keytruda + chemoPFS & OS (PFS & OS in TROP2 NMR+ve pts added as primary endpoints Jan 2026)Data due 2027 (prev H1 2026)Tropion-Lung081st-line non-sq NSCLC (PD-L1≥50%)+ Keytruda, vs KeytrudaPFS & OS (PFS & OS in TROP2 NMR+ve pts added as key secondary endpoints Apr 2026)Data due 2027 (prev H1 2026)Tropion-Lung101st-line non-sq NSCLC (PD-L1≥50%)Rilvegostomig +/- Datroway, vs KeytrudaPFS & OS in TROP2+ve ptsData due >2027Tropion-Lung172nd-line non-sq NSCLC (TROP2 NMR+ve)MonoRx, vs chemoPFS & OS co-primariesData due >2027Notes: QCS=quantitative continuous scoring; NMR=normalised membrane ratio. Source: AstraZeneca. The recently initiated Tropion-Lung17 study was suspected to be using the QCS assay, given that it mandates TROP2 expression as an entry criterion. Astra has now confirmed this, stating that TROP2 positivity is being measured by NMR. This trial is key to overcoming the setback of Datroway’s failed Tropion-Lung01 study – in a similar setting but in TROP2 all-comers.Finally, Tropion-Lung10, a study combining Datroway with the anti-PD-1 x TIGIT MAb rilvegostomig, was already known to be employing the QCS assay, given that it was always designed primarily to test survival in TROP2-positive patients. Astra doesn't expect Tropion-Lung17 and 10 to read out until beyond 2027.

Still, this has come at a cost, with delays to the readouts of two more Datroway trials, Tropion-Lung07 and 08, being ascribed to the recent inclusion of this QCS (quantitative continuous scoring) assay. These come after the readout of Avanzar, the first pivotal Datroway study to explore the utility of the TROP2 test, was delayed twice.

The good news is that Avanzar is still expected to yield data in the second half of this year, Astra said on Wednesday. Avanzar, testing Datroway plus Infinzi and chemo in first-line NSCLC, has a complex design, with primary endpoints comprising PFS and OS in TROP2-positive non-squamous patients, and PFS and OS in biomarker-undefined non-squames.

TROP2 secret sauce

A tumour’s TROP2 expression is thought to be difficult to analyse, but enriching for this biomarker could be essential to dialling up the efficacy of TROP2-targeting molecules, which has so far rather underwhelmed.

Astra’s in-house QCS diagnostic was developed specifically for the TROP2 biomarker, and the company says it gauges the internalisation of an antibody inside the cell. TROP2 positivity is then expressed as a normalised membrane ratio (NMR), a measure of TROP2 expression in the membrane relative to the cytoplasm of tumour cells.

In addition to Avanzar, the QCS assay is now being used in Tropion-Lung08, another first-line NSCLC study, into which PFS and OS in the TROP2 NMR-positive population have been added as key secondary endpoints. This change has yet to be reflected in clinicaltrials.gov, but was disclosed in Astra’s first-quarter presentation.

In a similar way Astra/Daiichi in January added PFS and OS in TROP2 NMR-positive patients, this time as new co-primaries, to the endpoints of Tropion-Lung07. However, Tropion-07 and 08 were earlier due to yield data in the first half of 2026, but readout has recently slipped into 2027, Astra confirmed.

In a note to clients, Jefferies analysts attributed these delays specifically to the inclusion of the QCS biomarker into studies, and ApexOnco understands that this is accurate. However, it’s not clear what in particular – physician adoption, ease of use or time taken to generate the biomarker data, for instance – is causing such delays.

Phase 3 Datroway trials that use the QCS assay for TROP2

Study	Setting	Regimen	Primary endpoints	Timeline
Avanzar	1st-line NSCLC	+ Imfinzi + chemo, vs Keytruda + chemo	PFS & OS in TROP2+ve non-sq; PFS & OS in all non-sq	Data due H2 2026 (prev H2 2025)
Tropion-Lung07	1st-line non-sq NSCLC (PD-L1<50%)	+ Keytruda +/- chemo, vs Keytruda + chemo	PFS & OS (PFS & OS in TROP2 NMR+ve pts added as primary endpoints Jan 2026)	Data due 2027 (prev H1 2026)
Tropion-Lung08	1st-line non-sq NSCLC (PD-L1≥50%)	+ Keytruda, vs Keytruda	PFS & OS (PFS & OS in TROP2 NMR+ve pts added as key secondary endpoints Apr 2026)	Data due 2027 (prev H1 2026)
Tropion-Lung10	1st-line non-sq NSCLC (PD-L1≥50%)	Rilvegostomig +/- Datroway, vs Keytruda	PFS & OS in TROP2+ve pts	Data due >2027
Tropion-Lung17	2nd-line non-sq NSCLC (TROP2 NMR+ve)	MonoRx, vs chemo	PFS & OS co-primaries	Data due >2027

Notes: QCS=quantitative continuous scoring; NMR=normalised membrane ratio. Source: AstraZeneca.

The recently initiated Tropion-Lung17 study was suspected to be using the QCS assay, given that it mandates TROP2 expression as an entry criterion. Astra has now confirmed this, stating that TROP2 positivity is being measured by NMR. This trial is key to overcoming the setback of Datroway’s failed Tropion-Lung01 study – in a similar setting but in TROP2 all-comers.

Finally, Tropion-Lung10, a study combining Datroway with the anti-PD-1 x TIGIT MAb rilvegostomig, was already known to be employing the QCS assay, given that it was always designed primarily to test survival in TROP2-positive patients. Astra doesn't expect Tropion-Lung17 and 10 to read out until beyond 2027.