Serial Multiomics Reveals Hidden Responses to Oncolytic Therapy in Glioblastoma

A recent study challenges long-held assumptions about monitoring glioblastoma (GBM) treatment response, demonstrating that serial tumor biopsies combined with multiomic analysis can uncover significant biological activity undetectable by conventional imaging. The findings, published by Ling et al. in Science Translational Medicine, offer a new window into the dynamic tumor-immune landscape of recurrent glioblastoma (rGBM), a notoriously treatment-resistant malignancy.

The study reports on the first two patients enrolled in a clinical trial of CAN-3110, an investigational oncolytic herpes simplex virus (oHSV) therapy delivered via intratumoral injections. Over a four-month period, researchers collected 97 biopsy cores from these patients, enabling deep, spatially and temporally resolved molecular analyses of the tumor microenvironment. This longitudinal tissue sampling, rarely feasible in GBM trials, revealed a cascade of immune-driven changes within the tumors—changes that would have gone unnoticed using magnetic resonance imaging (MRI) alone.

Despite MRI findings suggestive of disease progression, integrated multiomic profiling uncovered compelling evidence of treatment-induced activity. Both patients exhibited spatial remodeling of the tumor microenvironment following repeated CAN-3110 administration, including expansion of tissue-resident effector memory T cell clonotypes targeting viral and potentially tumor-associated antigens. Expression of cancer-testis antigens and other human leukocyte antigen (HLA)-presented immunopeptides was also observed, indicating engagement of adaptive immune responses within the tumor bed.

The clinical implications are twofold. First, the molecular evidence points to a potential therapeutic benefit from CAN-3110, even in cases where standard imaging might suggest otherwise. One patient achieved a pathological response, and the other demonstrated stable disease—an outcome not typically associated with recurrent GBM, where prognosis remains poor and therapeutic options are limited.

Second, and perhaps more consequentially, the study validates the feasibility of serial intratumoral sampling in rGBM and its value in uncovering mechanistic insights. Traditionally, GBM trials have relied on MRI as the principal, if not sole, modality for monitoring treatment response. However, imaging alone may fail to differentiate between true progression, pseudoprogression, or inflammatory responses induced by immunotherapies—a growing category of agents under investigation for GBM.

By integrating transcriptomic, proteomic, and immunopeptidomic data from sequential biopsies, Ling et al. demonstrate that tumor evolution during therapy can be measured in real time. This approach allows for the detection of immune remodeling, identification of tumor-intrinsic resistance pathways, and mapping of antigen-specific T cell responses—all critical for evaluating therapeutic efficacy in a disease as heterogeneous and adaptive as GBM.

These findings arrive at a moment when oncolytic viruses and other immunotherapeutics are beginning to gain traction in neuro-oncology, but still face significant challenges related to trial design, endpoint selection, and biomarker development. The ability to directly sample and analyze the tumor during treatment, as demonstrated here, may offer a path forward—not only to evaluate drug efficacy more precisely but to accelerate the identification of predictive markers and resistance mechanisms.

Although the current study is limited to two patients, it represents a significant methodological advance in GBM research. Larger trials incorporating serial multiomic sampling will be needed to determine whether these early findings generalize across patient populations and to what extent they correlate with longer-term clinical outcomes. Nonetheless, the work sets a precedent for more nuanced, biologically informed approaches to monitoring and understanding glioblastoma therapies.

As the field pushes toward more targeted and immune-based strategies, tools that reveal the hidden dynamics of tumor response—beyond what imaging can capture—may prove essential to unlocking new therapeutic avenues in one of oncology’s most intractable diseases.