Highlights
Immune checkpoint therapy has already altered the treatment landscape for pediatric and adolescent Hodgkin lymphoma, particularly in relapsed or high-risk disease where PD-1 blockade has shown substantial activity.
Among pediatric non-Hodgkin lymphomas, the strongest biologic rationale for checkpoint inhibition appears in tumors with consistent PD-L1 expression, including primary mediastinal B-cell lymphoma, anaplastic large cell lymphoma, aggressive natural killer-cell lymphoma, and some peripheral T-cell lymphomas.
The field is moving from salvage therapy toward earlier-line incorporation. A major randomized phase III study evaluating nivolumab with chemo-immunotherapy in newly diagnosed primary mediastinal B-cell lymphoma has completed accrual, with results anticipated in 2027.
Despite the excitement, pediatric evidence remains uneven across histologies. Biomarker selection, optimal treatment timing, long-term immune toxicity surveillance, and integration with curative multi-agent regimens remain key unanswered questions.
Background and Clinical Context
Immune checkpoint therapy (ICT) is designed to restore anti-tumor T-cell function by interrupting inhibitory signaling pathways that cancers exploit to evade immune destruction. The two best-established targets in clinical practice are cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed death 1 (PD-1). In lymphoma, especially in subtypes with high programmed death ligand 1 (PD-L1) expression or genetic mechanisms that drive immune evasion, blockade of the PD-1/PD-L1 axis has proved particularly relevant.
In pediatric oncology, the importance of checkpoint inhibition differs by disease. Unlike some common childhood cancers that have low mutational burden and limited responsiveness to immunotherapy, several pediatric and adolescent lymphomas display a biology that is unusually compatible with checkpoint blockade. Classical Hodgkin lymphoma is the clearest example. Reed-Sternberg cells often overexpress PD-L1 and PD-L2, frequently through 9p24.1 amplification and associated JAK/STAT signaling, creating a compelling therapeutic vulnerability. This biology helps explain why PD-1 inhibitors have demonstrated robust activity even in heavily pretreated Hodgkin lymphoma.
The article by Hoogstra and colleagues places this progress in a pediatric-specific framework. Their review emphasizes that checkpoint therapy is no longer a speculative strategy in childhood lymphoma; rather, it is an established modality in pediatric Hodgkin lymphoma and an increasingly plausible option in selected non-Hodgkin lymphoma subtypes. At the same time, the review makes clear that the field remains biologically heterogeneous. Some mature B-cell lymphomas show variable PD-L1 expression and therefore weaker or less predictable rationale, whereas others such as primary mediastinal B-cell lymphoma appear much more suitable for checkpoint-based approaches.
Mechanistic Rationale for Checkpoint Therapy in Pediatric Lymphomas
Checkpoint inhibitors act by lifting inhibitory brakes on T lymphocytes. PD-1 is expressed on activated T cells, and engagement with PD-L1 or PD-L2 suppresses cytotoxic activity, cytokine production, and sustained immune surveillance. Tumors that constitutively express PD-L1 can therefore induce local immune tolerance. In cancers where this pathway is dominant, PD-1 blockade may reactivate exhausted or suppressed anti-tumor T cells.
This mechanism has direct translational relevance in several pediatric lymphomas. In classical Hodgkin lymphoma, the malignant Reed-Sternberg cell is often a minority population within a highly inflammatory microenvironment, making immune crosstalk central to disease biology. In primary mediastinal B-cell lymphoma, recurrent 9p24.1 alterations and PD-L1 expression echo some features of Hodgkin lymphoma, further supporting the use of PD-1 inhibition. In ALCL, ANKL, and certain PTCL subsets, PD-L1 expression also provides a biologic basis for investigation, although the surrounding immune context and prior therapies may alter responsiveness.
The CTLA-4 pathway has been less central in lymphoma practice than PD-1 inhibition. Most of the clinically meaningful evidence in pediatric and adolescent lymphomas has centered on nivolumab and pembrolizumab rather than CTLA-4 inhibitors, either alone or in combination.
What This Review Adds
Rather than presenting a single trial, this article synthesizes the current state of checkpoint therapy across pediatric and adolescent lymphoma subtypes. Its main contribution is practical stratification: where checkpoint blockade is already clinically impactful, where the evidence is emerging, and where biology is suggestive but clinical validation remains limited.
The review identifies three broad clinical zones. First, pediatric Hodgkin lymphoma is the most mature setting, with meaningful efficacy in relapsed disease and growing interest in front-line or response-adapted strategies. Second, selected non-Hodgkin lymphomas with consistent PD-L1 expression represent the most attractive expansion targets. Third, other mature B-cell lymphomas with variable PD-L1 expression remain investigational, and routine incorporation of checkpoint inhibitors cannot yet be justified.
Key Findings by Lymphoma Subtype
Pediatric Hodgkin lymphoma: the leading success story
The strongest clinical impact of checkpoint inhibition in children and adolescents has been seen in classical Hodgkin lymphoma. This is entirely consistent with disease biology and aligns with adult experience, where PD-1 inhibitors have produced high response rates in relapsed or refractory disease. In pediatric care, these agents are particularly relevant for patients with relapse after standard chemotherapy, after brentuximab vedotin exposure, or in high-risk scenarios where reducing cumulative toxicity from repeated cytotoxic therapy is desirable.
The importance of this success goes beyond response rates. In young patients, salvage treatment decisions are shaped not only by disease control but also by long-term survivorship concerns, including infertility, cardiopulmonary toxicity, neurotoxicity, and second cancers. A highly active immunotherapeutic class offers the possibility of disease control with a different toxicity spectrum. That does not eliminate risk, because immune-related adverse events can affect endocrine, hepatic, pulmonary, gastrointestinal, dermatologic, and other organ systems, but it changes the tradeoff in a potentially favorable way.
The review notes that checkpoint inhibitors have shown remarkable efficacy in both high-risk and relapsed pediatric Hodgkin lymphoma, with ongoing investigation in lower-risk disease. This is a pivotal point. Once a therapy proves effective in relapse, the next strategic question is whether it can safely improve cure rates, reduce radiation exposure, decrease cumulative chemotherapy burden, or improve quality of life when moved earlier in treatment. Those questions are now central to pediatric Hodgkin lymphoma trial design.
Mature B-cell lymphomas: heterogeneous biology, limited pediatric experience
In pediatric mature B-cell lymphomas overall, the biologic rationale for checkpoint inhibition is less uniform. PD-L1 expression varies, and the available pediatric experience remains sparse. This matters because biomarker inconsistency reduces confidence that PD-1 blockade will produce reproducible benefit across the group. For routine practice, this means clinicians should be cautious about extrapolating from Hodgkin lymphoma or from isolated adult studies.
The clearest exception within the mature B-cell category is primary mediastinal B-cell lymphoma. Here, the overlap with Hodgkin lymphoma biology strengthens the case for PD-1 blockade. By contrast, for other mature B-cell subtypes, checkpoint inhibition should still be considered investigational unless supported by trial participation, molecular rationale, or exceptional clinical circumstances.
Primary mediastinal B-cell lymphoma: strongest non-Hodgkin rationale
Primary mediastinal B-cell lymphoma (PMBCL) is especially important because it sits at the interface of pediatric and young adult oncology and has biologic features that make it a natural candidate for checkpoint therapy. PD-L1 expression is common, and the disease has already shown sensitivity to PD-1 blockade in adult relapsed settings.
The review highlights a major cooperative group effort: the Children’s Oncology Group and the National Cancer Institute National Clinical Trials Network have recently completed a randomized phase III trial evaluating nivolumab combined with chemo-immunotherapy in children and adults with newly diagnosed PMBCL, with results expected in 2027. This is arguably one of the most practice-relevant ongoing studies in the field. If positive, it could validate earlier-line checkpoint integration in a lymphoma subtype where therapeutic intensification can carry substantial toxicity.
For clinicians, the significance is twofold. First, PMBCL may become the first pediatric non-Hodgkin lymphoma outside Hodgkin disease in which checkpoint therapy is meaningfully embedded into standard initial management. Second, a positive trial would further reinforce biomarker-driven and histology-specific use of immunotherapy rather than broad, undifferentiated application across all NHL subtypes.
Anaplastic large cell lymphoma and aggressive natural killer-cell lymphoma
ALCL and ANKL both have strong biologic rationale for checkpoint inhibition based on consistent PD-L1 expression. This is especially notable because these are clinically challenging diseases, and in some settings conventional options are limited by relapse risk or by the aggressive pace of illness. Ongoing clinical trials are testing whether PD-1 pathway blockade can translate biologic plausibility into meaningful response durability and survival benefit.
At present, however, these diseases remain investigational checkpoint targets. The field still needs clarity regarding which patients benefit most, how checkpoint inhibitors should be sequenced relative to transplantation or targeted therapies, and whether combination regimens are required for durable disease control.
Peripheral T-cell lymphoma, not otherwise specified
Peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) also appears to have biologic features supportive of checkpoint therapy, including PD-L1 expression in at least a subset of cases. However, T-cell lymphomas introduce additional complexity. The immune system is not just the effector of therapy but also the tissue of origin of the malignancy. This creates theoretical and practical concerns, including variable biology, risk of hyperprogression in some T-cell neoplasms described outside the pediatric setting, and uncertainty about which checkpoint strategy is most appropriate.
For that reason, although the rationale is strong enough to justify clinical investigation, checkpoint blockade in PTCL should remain trial-based whenever possible.
Safety and Clinical Integration
Checkpoint inhibitors are often perceived as less toxic than intensive chemotherapy, but this should not be mistaken for trivial toxicity. Immune-related adverse events can occur in any organ system and may be delayed, recurrent, or persistent. In children and adolescents, the long-term implications are particularly important. Endocrinopathies such as hypothyroidism, adrenal dysfunction, and insulin-requiring diabetes may have lifelong consequences. Pneumonitis, hepatitis, colitis, rash, and neurologic toxicities, while less common, can be severe.
Another issue unique to pediatric oncology is treatment layering. Checkpoint inhibitors are frequently being added to already complex regimens that may include anthracyclines, alkylators, radiation, antibody-drug conjugates, stem cell transplantation, or cellular therapy. Determining whether toxicity is overlapping, additive, or synergistic will require longer follow-up than is currently available in many pediatric series.
There are also practical questions about timing. Should PD-1 blockade be used as bridge-to-transplant, post-transplant salvage, part of induction, or as consolidation in biomarker-selected patients? In adult Hodgkin lymphoma, the answer depends on treatment history and goals. In pediatric care, the answer must also account for growth, fertility, educational disruption, and survivorship trajectories.
Expert Commentary
The central message of this review is that checkpoint therapy in pediatric lymphoma should now be understood as disease-specific rather than class-wide. Hodgkin lymphoma has crossed the threshold from biologic promise to clinical reality. PMBCL is the next most likely candidate for front-line practice change, pending randomized trial results. ALCL, ANKL, and PTCL, NOS are compelling but still developmental indications.
This is a sound and clinically useful framing. It avoids two common errors: overgeneralizing immunotherapy success from one lymphoma subtype to all others, and assuming that pediatric evidence can be directly imported from adult populations. Pediatric and adolescent lymphomas often share biology with adult disease, but treatment context, toxicity priorities, and trial feasibility are distinct.
Another strength of the review is its focus on PD-L1 expression as a biologic anchor. That said, PD-L1 alone is unlikely to be sufficient as a predictive biomarker. Expression assays are variable, thresholds are inconsistent, and response probably depends on a broader ecosystem that includes 9p24.1 status, Epstein-Barr virus biology in some entities, tumor microenvironment composition, prior therapy, and T-cell functional state. Future research will need more refined biomarkers than PD-L1 immunohistochemistry alone.
One limitation of the current evidence base is that pediatric data remain concentrated in a few diseases and often derive from small cohorts, early-phase trials, or extrapolation from adolescent and young adult populations. This is unavoidable in rare malignancies but underscores the value of cooperative group studies and international collaboration. Another limitation is the lack of mature survivorship data. In a field where cure is common for many patients, durability of remission and long-term toxicity matter as much as initial response.
Implications for Practice and Research
For current practice, checkpoint inhibition should be viewed as an important established option in pediatric and adolescent Hodgkin lymphoma, especially in relapsed or high-risk settings. For PMBCL, clinicians should watch closely for the forthcoming phase III data, which may define a new standard if efficacy and tolerability are favorable. For ALCL, ANKL, and PTCL, NOS, clinical trial enrollment remains the preferred path.
The next generation of studies should aim to answer several concrete questions. Can checkpoint therapy reduce exposure to radiotherapy or intensive salvage chemotherapy in Hodgkin lymphoma? Which biomarkers best identify benefit in non-Hodgkin subtypes? What is the optimal duration of therapy in children? How should checkpoint inhibitors be integrated with brentuximab vedotin, rituximab-containing regimens, transplantation, and newer cellular therapies? And critically, what are the long-term endocrine, pulmonary, reproductive, and psychosocial effects in survivors treated during childhood or adolescence?
If those questions are answered rigorously, checkpoint therapy may ultimately become not just a rescue strategy but a tool for improving both cure and survivorship in selected pediatric lymphomas.
Conclusion
Immune checkpoint therapy has emerged as one of the most consequential immuno-oncology advances in pediatric and adolescent lymphoma. Its clearest success to date is in pediatric Hodgkin lymphoma, where PD-1 blockade has demonstrated substantial efficacy and is now influencing treatment strategy across risk groups. Beyond Hodgkin lymphoma, the field is entering a decisive expansion phase driven by tumor biology, especially PD-L1 expression. PMBCL is the leading non-Hodgkin candidate for near-term practice change, while ALCL, ANKL, and PTCL, NOS remain highly promising investigational targets.
The major challenge now is disciplined translation: matching the right checkpoint strategy to the right lymphoma subtype, at the right treatment time point, with careful attention to pediatric-specific toxicity and survivorship. The promise is real, but so is the need for precision.
Funding and ClinicalTrials.gov
The source article is a narrative review and does not, in the abstract provided, specify funding details. The review highlights a completed randomized phase III cooperative group study of nivolumab plus chemo-immunotherapy in newly diagnosed PMBCL conducted through the Children’s Oncology Group and the NCI National Clinical Trials Network; readers should consult the final publication and ClinicalTrials.gov listing when available for protocol-specific registration and funding information.
References
Hoogstra DJ, Xavier AC, Harker-Murray P, Alexander S, Giulino-Roth L, Hernandez TA, Cairo MS. Immune checkpoint therapy in pediatric and adolescent lymphomas. Haematologica. 2026-06-04. PMID: 42237783.
Ansell SM, Lesokhin AM, Borrello I, et al. PD-1 blockade with nivolumab in relapsed or refractory Hodgkin’s lymphoma. N Engl J Med. 2015;372(4):311-319.
Chen R, Zinzani PL, Fanale MA, et al. Phase II study of the efficacy and safety of pembrolizumab for relapsed/refractory classic Hodgkin lymphoma. J Clin Oncol. 2017;35(19):2125-2132.
Kuruvilla J, Ramchandren R, Santoro A, et al. Pembrolizumab versus brentuximab vedotin in relapsed or refractory classical Hodgkin lymphoma: phase 3 KEYNOTE-204 study. Lancet Oncol. 2021;22(4):512-524.
Zinzani PL, Ribrag V, Moskowitz CH, et al. Safety and tolerability of pembrolizumab in patients with relapsed/refractory primary mediastinal large B-cell lymphoma. Blood. 2017;130(3):267-270.
National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Hodgkin Lymphoma. Most recent publicly available version should be consulted for contemporary recommendations.