Prospective ctDNA Testing in Large B-Cell Lymphoma

This is a multicenter, prospective, observational cohort study evaluating the prognostic value of circulating tumor DNA (ctDNA), measured using PhasED-seq, in patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) or high-grade B-cell lymphoma (HGBL). Approximately 100 patients will be enrolled. The primary objective is to assess the association between post-treatment ctDNA status and subsequent progression-free survival (PFS).

Patients will undergo baseline PET/CT imaging and tumor tissue next-generation sequencing (NGS). First-line immunochemotherapy will be selected and managed by the treating physician according to routine clinical practice and will not be assigned by the study. Interim PET/CT assessment is planned after 3 cycles of treatment, and post-treatment PET/CT is planned approximately 8 weeks after completion of first-line therapy. Plasma samples for PhasED-seq ctDNA analysis will be collected before initiation of first-line therapy, after 3 cycles of treatment, and approximately 8 weeks after completion of first-line therapy, within the protocol-specified sampling windows.

The primary analysis will include patients who are alive and progression-free at the protocol-specified post-treatment ctDNA blood draw and have an evaluable ctDNA result. Patients will be classified as ctDNA-positive or ctDNA-negative according to the result from this blood draw. PFS will be measured from this blood draw to the first documented disease progression or death from any cause, whichever occurs first, with a primary observation period of 18 months.

Additional analyses will evaluate overall survival and the associations of interim ctDNA status, baseline ctDNA status, and baseline tumor molecular subtype with post-treatment PFS. These analyses will use the primary analysis population, restricted as necessary to patients with evaluable results for the marker being investigated. Associations involving earlier biomarkers will therefore describe subsequent outcomes among patients who remain alive and progression-free at the post-treatment assessment. PET/CT findings will be examined alongside ctDNA findings in exploratory analyses.

Patients who discontinue or change first-line treatment will remain in the enrolled cohort. Subsequent treatment and clinical outcomes will continue to be recorded where consent permits. Inclusion in each analysis population and the handling of missing or unevaluable results will follow prespecified criteria in the study protocol and statistical analysis plan. An unevaluable ctDNA result will not be classified as ctDNA-negative.

• Standard-of-care first-line immunochemotherapy containing an anti-CD20 monoclonal antibody and an anthracycline, such as R-CHOP, Pola-R-CHP, or DA-EPOCH-R. (Drug): First-line immunochemotherapy containing an anti-CD20 monoclonal antibody and an anthracycline, such as R-CHOP, Pola-R-CHP, or DA-EPOCH-R. Treatment selection and modification are determined by the treating physician as part of routine clinical care and are not assigned by the study.

Primary outcomes

• Progression-free survival following post-treatment ctDNA assessment [From the protocol-specified post-treatment ctDNA blood draw through 18 months after the blood draw.]: Progression-free survival is defined as the time from the protocol-specified post-treatment ctDNA blood draw, scheduled approximately 8 weeks after completion of first-line therapy, to the first documented disease progression or death from any cause, whichever occurs first. The primary analysis will include patients who are alive and progression-free at this blood draw and have an evaluable ctDNA result. Patients will be classified according to ctDNA status at this same blood draw. Patients without an event will be censored at their last adequate disease assessment or 18 months after the blood draw, whichever occurs first.

Secondary outcomes

• Overall Survival [From the protocol-specified post-treatment ctDNA blood draw through 18 months after the blood draw.]: Overall survival is defined as the time from the protocol-specified post-treatment ctDNA blood draw to death from any cause. OS will be compared according to ctDNA status at this blood draw. Patients who remain alive will be censored at the last date they are known to be alive or 18 months after the blood draw, whichever occurs first.
• Correlation between interim ctDNA status and post-treatment progression-free survival [From the date of the post-treatment ctDNA blood draw through 18 months after the blood draw.]: The association between ctDNA status at interim assessment after 3 cycles of first-line therapy and post-treatment PFS will be evaluated among patients included in the primary analysis population. PFS will be defined as specified for the primary outcome.

Other outcomes

• Correlation between baseline ctDNA status and post-treatment progression-free survival [From the protocol-specified post-treatment ctDNA blood draw through 18 months after the blood draw.]: The association between baseline ctDNA status and post-treatment PFS will be evaluated among patients included in the primary analysis population. PFS will be defined as specified for the primary outcome.
• Correlation between baseline tumor molecular subtype and progression-free survival [From the protocol-specified post-treatment ctDNA blood draw through 18 months after the blood draw.]: The association between baseline tumor molecular subtype, determined using a prespecified classification method based on tissue NGS, and PFS following the protocol-specified post-treatment ctDNA blood draw will be evaluated. PFS will be defined as specified for the primary outcome.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Age ≥18 years, either sex.
* Histopathologically confirmed diffuse large B-cell lymphoma (DLBCL) or high-grade B-cell lymphoma (HGBL).
* Planned to receive standard immunochemotherapy including at least CD20 monoclonal antibody and anthracycline, such as Pola-RCHP, R-CHOP, or R-DA-EPOCH.
* No maintenance therapy planned after completion of first-line treatment.
* Written informed consent obtained.

Exclusion Criteria:

* DLBCL/HGBL transformed from indolent B-cell lymphoproliferative disorders.
* HIV-positive large B-cell lymphoma.
* Prior chemotherapy, targeted therapy, or immunotherapy for large B-cell lymphoma.
* Investigator-assessed ineligibility for this study.
* Concomitant other malignancies.

• Jin Lu, Principal investigator, Peking University People's Hospital