Diffuse pleural mesothelioma remains a uniquely challenging malignancy. Its growth pattern undermines conventional imaging, its biology yields scant circulating tumor signal, and debate exists around the value and timing of surgery. Against this backdrop, we asked two simple questions of central practical importance and clinical significance. First, can immune checkpoint blockade be given before and after surgery without derailing the operative plan or compromising safety in patients with resectable pleural mesothelioma? Second, can an ultra-sensitive, tumor-informed liquid biopsy provide a clinically meaningful molecular read-out of peri-operative immunotherapy outcomes, early enough to guide therapeutic decision making?
Patients with good performance status and multidisciplinary confirmation of operability received either neoadjuvant nivolumab alone or combined with a single dose of ipilimumab. All patients who underwent resection also received post-operative therapy, including adjuvant nivolumab for one year per protocol. The co-primary endpoints were feasibility, defined a priori as proceeding to surgery without protocol-defined delay, and safety, captured by dose-limiting toxicities during the neoadjuvant window. Progression-free and overall survival were evaluated as exploratory outcomes alongside tumor-informed, whole-genome sequencing liquid biopsy, measuring circulating tumor DNA (ctDNA) at baseline, through neoadjuvant therapy, immediately pre-operatively, and again post-operatively.
The clinical verdict on feasibility and safety was clear. More than four-in-five patients in each arm reached the operating room as planned, and complete macroscopic resection was achieved in most cases. Immune-related toxicities aligned with expectations for immunotherapy agents, and adjuvant nivolumab was generally well-tolerated. These findings address the core, practical anxiety that neoadjuvant immunotherapy might derail operability, which it did not.
Efficacy signals, while exploratory in this phase 2 clinical trial setting, were encouraging and coherent. Median progression-free and overall survival favored the combination of nivolumab with ipilimumab over nivolumab alone, and a meaningful fraction of patients in the combination arm remained alive and recurrence-free at the time of data analysis. One should avoid over-interpreting arm-to-arm contrasts in this small, sequentially-accrued study, but the pattern – durable control in a subset without dramatic radiographic responses – foreshadows the central translational lesson of this work.
That lesson is that, in mesothelioma, cell-free tumor DNA detection in the bloodstream is a more reliable indicator of treatment effect than tumor measurements on imaging. Conventional response rates by modified RECIST were modest, as expected in this pleural surface-spreading cancer type, which often thins rather than shrinks; yet the ctDNA assay drew a much sharper picture. By leveraging genome-wide mutation profiles from each patient’s tumor, and utilizing a machine learning framework to suppresses technical noise in cell-free DNA, we were able to detect extraordinarily low tumor levels and track ctDNA dynamics over time. Two clinically intelligible patterns emerged.
First, detectable ctDNA during the neoadjuvant window correlated with the feasibility endpoint at the heart of this trial. Patients who ultimately could not complete surgery – either because their disease progressed between planning and incision, or because the tumor proved unresectable intraoperatively – showed persistent or rising ctDNA levels, while still being nominally eligible on imaging. This is the kind of actionable information that can promptly redirect specific patients to alternative treatment strategies.
Second, ctDNA served as an indicator of long-term progression-free survival. Patients with undetectable ctDNA by the end of neoadjuvant therapy and immediately before surgery experienced substantially longer progression-free survival than those with residual ctDNA; this same pattern held, often more strongly, when one looked at two-timepoint dynamics. Significant drops in tumor fraction from baseline, or persistently undetectable ctDNA throughout the neoadjuvant course, were observed in patients most likely to attain durable control after surgery; additionally, post-operative re-emergence of ctDNA predicted disease recurrence. Importantly, these molecular trajectories frequently diverged from scan-based impressions. In other words, ctDNA captured the direction and velocity of disease progression and therapy response when imaging techniques could not.
It is worth pausing on what, precisely, we can and cannot claim based on these data. The notion that ctDNA is prognostic, i.e., that it stratifies patients by risk independent of treatment choice – is strongly supported here, since those without detectable ctDNA at key junctures attained better outcomes. Whether ctDNA is also predictive, i.e., whether its clearance specifically marks benefit from neoadjuvant checkpoint blockade, is a more nuanced claim in a non-randomized phase 2 study without a non-immunotherapy control arm. The temporal coupling of ctDNA reduction to neoadjuvant dosing, and the association with improved clinical outcomes, together make a persuasive case that the ctDNA signal is treatment-linked. However, definitive proof will require larger, prospective trials, adequately powered to prove the clinical benefit of a ctDNA-guided adaptive therapy.
Two practical implications follow immediately. First, the trial establishes that neoadjuvant checkpoint blockade can be considered among curative-intent therapy options for resectable mesothelioma without jeopardizing surgery. Second, ctDNA residual disease after neoadjuvant immunotherapy and prior to surgery – offers a crisp, quantitative, molecular read-out that may refine individual care. Clear molecular response supports proceeding to resection, while a persistent ctDNA signal should trigger a re-consideration of medical management. After resection, reappearance of ctDNA should prompt intensified surveillance and the swift deployment of systemic therapy.
No early-phase study is without limitations. Arms were accrued sequentially, and the participating sites brought deep surgical expertise that not all centers can immediately replicate. Mesothelioma’s low mutational burden and locoregional spread will always challenge liquid biopsy analytical and clinical sensitivity. Yet even within these constraints, the core conclusions hold; perioperative immunotherapy is feasible and safe, and ctDNA provides an accurate and timely account of tumor burden dynamics and therapeutic response – something imaging alone has not reliably delivered in this setting.
Taken together, the purpose of this trial was to determine whether perioperative immune checkpoint blockade is practical in resectable mesothelioma, and whether an ultra-sensitive tumor-informed ctDNA assay can serve as an early, clinically-useful biomarker. The result is yes on both counts. The therapy was feasible and safe, and the liquid biopsies were not merely measurable, but clinically informative, identifying patients likely to attain clinical benefit, signaling those at risk of surgical attrition or early recurrence, and offering a path to more adaptive, individualized, and precise perioperative care. As the field moves to larger studies, these findings provide a clear blueprint; keep immunotherapy in the perioperative conversation, and let ctDNA, measured carefully and interpreted judiciously, guide the rhythm of that dialogue.
Precision oncology has fundamentally reshaped the treatment paradigm within the field, with individualized biomarker-matched therapies enhancing the arsenal oncologists use to manage cancer.
For the evolving ecosystem of precision oncology to advance toward a nationwide integration, efforts should focus on expanding access to genomic expertise, molecular tumor boards, and clinical trial infrastructure – resources that remain scarce outside academic centers. There thus arises a need to shift the strategic approach to advancing precision oncology so that it emphasizes not only technological and pharmacological progress but also clinical utility and broader accessibility.
Significant efforts have been made toward establishing comprehensive molecular profiling in first-line decision-making, where clinically appropriate. Non–small cell lung cancer (NSCLC) has long exemplified the integration of baseline molecular testing; where genomic alterations such as EGFR mutations, ALK and ROS1 rearrangements, MET exon 14 skipping, BRAF V600E mutations, and PD-L1 expression levels are systematically assessed to guide personalized therapy. Similarly, in breast cancer, estrogen receptor (ER) and progesterone receptor (PR) expression, and epidermal growth factor receptor 2 (HER2) expression/amplification are predictive biomarkers evaluated at baseline. Furthermore, tumor genotyping for PIK3CA and ESR1 mutations has become clinically actionable, with FDA approvals of specific drug classes for these biomarker-defined subsets of hormone receptor-positive breast cancer. These models illustrate that when actionable biomarkers are implemented, testing informs therapeutic decision-making and improves clinical outcomes.
In terms of real-time monitoring of tumor burden and therapeutic response, liquid biopsy analyses have emerged as paradigm-shifting technologies; longitudinally assessing circulating tumor DNA (ctDNA) dynamics and evaluating residual disease across stages and therapies. Liquid biopsies also allow for tracking tumor evolution, detecting emerging resistance, elucidating mixed responses or stable disease, and identifying recurrence before it becomes radiographically or clinically apparent.
Establishing precision oncology as the standard of care, however, requires two key elements: technology to advance cancer discovery and education to scale its impact. By providing expert molecular interpretation and implementing decision-support tools in community clinics, we can expand access and enrolment in biomarker-matched therapies and clinical trials.
At this precise intersection – between education and technology – we are building a precision-oncology decision-support platform embedded within the Johns Hopkins Molecular Tumor Board to standardize evidence assessment and expand equitable access to expert interpretation and recommendations. In line with the scope of the NCI Community Oncology Research Program – which bridges clinical trials and care delivery research with community clinics – we envision that our initiatives will help operationalize precision oncology and create clear on-ramps to clinical trial screening and enrolment.
Outreach programs tailored for community oncologists, improved referral networks, and regionally or virtually hosted case-based molecular tumor boards (MTBs) have further democratized access to genomic expertise and improved clinician confidence in navigating molecular findings. Importantly, these educational models should be sensitive to workflow realities in high-burden settings and emphasize the clinical utility of precision oncology approaches. Expanding genomic literacy beyond the physician level to include nurse navigators, genetic counsellors, and case managers can further support patient-centered education, and increased engagement in shared decision-making processes, including clinical trial participation.
Internationally, promising models are emerging. Regional MTBs supported by international consortia have demonstrated feasibility and clinical benefit even in resource-constrained settings, providing a blueprint for scalable transnational and supranational precision oncology frameworks.
The future of oncology depends not only on identifying new biomarkers and developing advanced targeted therapies, but also on breaking down the educational and logistical barriers that restrict their access. Through the meaningful work of precision oncology groups, including our own at the Johns Hopkins MTB, we are hopeful that soon precision oncology will evolve from a specialized innovation into an accessible standard, embedded across all levels and stages of the cancer care continuum.
Over the past decade, significant progress has been achieved in treating lung cancer, particularly for individuals with non-small cell lung cancer (NSCLC). In particular, the development of immune checkpoint inhibitors – which harness a patient’s immune system to fight cancer – has resulted in significant improvements in patient outcomes. Immune checkpoint inhibitors work by blocking inhibitory molecules that cancer cells use to evade immune surveillance, enabling the patient’s immune system to target cancer cells. This therapeutic approach is entirely unlike chemotherapy, which targets all rapidly dividing cells and thus has the potential to target some healthy cells – e.g., hair cells and cells in the lining of the digestive tract.
Still, not all patients attain clinical benefit from these novel immunotherapies. Some lung cancers harbor an “immunologically cold” phenotype, meaning they are more likely to evade immune recognition and elimination by the immune system even when treated with immune checkpoint inhibitors. For example, tumors with fewer somatic mutations, which are considered to have a low tumor mutation burden (TMB), and tumors with no PD-L1 expression, generally show a poorer response to immunotherapy. This raises the question of how we can improve responses to immunotherapy in patients with tumors that are predisposed to resistance.
Preclinical evidence suggests that radiation therapy (RT) could help circumvent immunotherapy resistance. When cancer cells are subjected to RT, they release antigens into the nearby environment, known as the tumor microenvironment (TME). The immune system can then recognize these antigens and tailor immune responses to the molecular “blueprint” of the cancer. In this way, RT may be able to enhance anti-tumor immune responses, both at the primary tumor treated with radiation and systemically, and at distant metastases far from the site of radiation. This effect is known as the abscopal effect of radiation (‘ab’ meaning away from, and ‘scopus’ meaning target).
These findings suggest that RT could enhance the response to immunotherapy, even at distant metastatic sites. However, this effect has not been consistently shown, especially in human biospecimens. To bridge this gap, we studied how lung cancers responded to immunotherapy in a phase 2 randomized clinical trial of patients with NSCLC receiving combination radioimmunotherapy. In one arm of this trial, patients received radiotherapy together with pembrolizumab, while in the control arm, patients received pembrolizumab alone.
To study each tumor’s response to therapy at the molecular and cellular level, our team analyzed 293 tissue and blood specimens derived from patients in this trial, from both pre-therapy and on-therapy timepoints. Using whole-exome sequencing and gene expression analyses, we identified tumors that harbored features of immunotherapy resistance and immunologically cold phenotypes. We were particularly interested in patients with this immunologically cold tumor phenotype and hypothesized that radiotherapy may circumvent immunotherapy resistance and sensitize such lung cancers to pembrolizumab. Below are the main insights from our research study.
We found that patients who received combination immunotherapy with RT showed enhanced anti-tumor immune responses, including in metastatic sites that were not irradiated. We examined gene expression patterns in the TME and observed an upregulation of key genes involved in inflammatory response and immune cell activation. This was also reflected in a greater number of T-cells, B-cells, macrophages, and natural-killer cells being recruited to the TME. As these phenomena were notes in tumors that harbored characteristics of immune resistance due to an immunologically cold TME, our findings supported a cold-to-hot transition of the TME, that we posit was driven by radiotherapy. This rewiring of the TME towards a more inflamed, immunologically “hot” phenotype enabled better clinical responses with immunotherapy.
Our second key finding was that, in the combination radioimmunotherapy arm, existing T-cells increased in density in both the blood and tissue compartments together with the appearance of new T cell clones. T-cells rely on T-cell receptors (TCRs) to recognize antigens, including tumor-associated and neoantigen-associated neoantigens. We employed T-cell receptor sequencing focusing on the antigen-recognizing domains to study changes in the T cell repertoire with radioimmunotherapy. Our hypothesis going into these analyses, based on our transcriptomic data, was that we would observe a reshaping of the T cell repertoire characterized by an influx and expansion of T cells in non-irradiated sites for patients who received radiation in addition to immunotherapy. Indeed, we found that patients who received RT in addition to immunotherapy exhibited an expansion of both existing and new TCRs, consistent with an enhanced immune response.
But were these T cells targeting the cancer cells? To answer this question, we cultured T-cells ex vivo from selected patients who attained long-term clinical outcomes with radioimmunotherapy despite their tumors having molecular features of resistance to immunotherapy. This led to our third key finding – that mutation-associated neoantigens elicited tumor-reactive clonotypic T cell expansions. This provided definitive evidence of the presence and enhancement of anti-tumor immune responses in the context of radioimmunotherapy.
Ultimately, when examining the clinical outcomes of patients who received radioimmunotherapy, we found that the phenomenon of the TME in non-irradiated metastatic sites warming up with radiotherapy was mainly observed in patients with the longest survival. Overall, patients who received radioimmunotherapy had significant tumor shrinkage at non-irradiated metastatic sites. This was especially evident in patients with tumors that initially exhibited an immunologically cold phenotype, and as a result, were not expected to benefit from immunotherapy.
Ultimately, our study highlights the potential application of RT in combination with immunotherapy for treating patients with NSCLC, particularly those with immunologically cold tumors who may otherwise have a poor response to immunotherapy alone. Taken together, our findings at the molecular, cellular, and systemic levels suggest that combination radioimmunotherapy may help circumvent immunotherapy resistance.
Our open-access study (DOI) was published in Nature Cancer on Tuesday, July 22nd, 2025.
The field of oncology is experiencing a paradigm shift through the integration of liquid biopsies, which are non-invasive diagnostic methods that analyze circulating tumor DNA (ctDNA) in blood samples. These advanced technologies are transforming lung cancer care by allowing clinicians to detect genetic mutations, monitor disease progression, and assess treatment responses with molecular precision.
In a recent episode of “Lung Cancer Considered,” a podcast hosted by the International Association for the Study of Lung Cancer (IASLC), Dr. Stephen Liu interviewed liquid biopsy experts Dr. Valsamo (Elsa) Anagnostou and Dr. Umberto Malapelle about the evolving role of liquid biopsy in clinical practice. The discussion highlighted how this innovative approach is especially valuable for identifying actionable mutations that can guide the selection of targeted therapies. Compared to traditional tissue biopsies, liquid biopsy reduces procedural risks and allows for more frequent monitoring, enabling oncologists to detect treatment resistance in real time. Furthermore, the cost-effectiveness and accessibility of liquid biopsy render it a practical solution for ongoing patient care, minimizing the need for invasive procedures while delivering timely molecular insights. As we continue to refine these technologies, their integration into routine clinical workflows can improve outcomes for lung cancer patients worldwide.
Follow the [link] for the podcast episode to listen to the full conversation and gain deeper insights into the future of lung cancer diagnostics.
In this study, our group at the Johns Hopkins Kimmel Cancer Center demonstrated that a minimally invasive blood test effectively captures early responses to immunotherapy in patients with advanced lung cancer. By measuring circulating tumor DNA (ctDNA) levels, this liquid biopsy approach provides monitoring of therapy response with molecular precision and predicts survival. This advancement holds great potential for molecular response-adaptive treatment decision-making.
To gain a deeper insight, view the following video, “Capturing Immunotherapy Response in a Blood Drop”.
