Malignant Peripheral Nerve Sheath Tumors Activate Distinct Immunosuppressive Pathways Following Radiotherapy and are Associated with Immune Depletion In Vivo

PURPOSE/OBJECTIVE(S)

Patients with neurofibromatosis type I, caused by NF1 loss, develop benign plexiform neurofibromas (pNF) in their peripheral nervous system (PNS). Malignant transformation of pNFs into malignant peripheral nerve sheath tumors (MPNSTs) occurs following CDKN2A/B and SUZ12 loss, a process associated with radiotherapy (RT). However, the molecular mechanisms underlying RT responses by different PNS cell types remain unclear. We hypothesized normal peripheral nerve cells, pNFs, and MPNSTs harbor distinct RT responses.

MATERIALS/METHODS

Patient derived NF1 WT immortalized peripheral nerve cells (iPNs), NF1 mutant pNF cells, and NF1/CDKN2AB/SUZ12 mutant MPNST cells were used to study RT responses in vitro. CRISPRi was used to assess the functional effects of candidate gene repression. In vitro viability was measured by cell counts. Transcriptomic signatures were measured by bulk RNA-sequencing and integrated with single-cell RNA sequencing (scRNA-seq) data from patient-derived pNF and MPNST resection specimens.

RESULTS

Radiation dose response curves revealed pNF cells (IC50 0.61 Gy) were more radiosensitive than MPNST cells (4.15 Gy). WT iPNs, NF1 deficient iPNs, and pNFs cells displayed no difference in cell viability (p = 0.67; t-test) following initiation of 2 Gy x 5 fractions, while MPNST cells were significantly more viable (p = 0.02; t-test). Principal component analysis of bulk RNA-sequencing data at 5 or 14 days following 2 Gy x 5 fractions revealed cell line of origin accounted for the greatest inter-sample variation (64.9% variance), with additional components separating samples based on radiation presence and timing. Using the most variable genes in PCA space to identify markers of RT response, iPNs and pNFs upregulated pro-apoptotic pathways (BAD, DAPK3) at 5 days post-radiation while MPNST cells alone upregulated pro-survival growth factor signaling). At 14 days post radiation, MPNST cells uniquely upregulated TGFβ signaling and interferon response circuits. Incorporation of scRNA-seq data revealed enrichment of growth factor signaling and TGFβ signatures in MPNSTs compared to pNF. Moreover, MPNST harbored significantly fewer immune cells than pNFs (p = 0.008, t-test), suggesting cell-autonomous signaling and crosstalk with the microenvironment are both critical to MPNST radioresistance.

CONCLUSION

Our data indicate additional genetic hits beyond NF1 loss may be required for RT-associated malignant transformation of pNFs and radioresistance in MPNSTs. Analysis of transcriptomic responses to RT suggests that upregulated growth factor signaling and TGFβ-associated immunosuppression are distinct features of MPNST. Future work will focus on CRISPRi screens to unbiasedly nominate functional modifiers of RT response in NF1/CDKN2AB deficient tumors, which may be broadly useful in cancer.

Multi-Institutional Report of Re-Irradiation for Recurrent High-Grade Glioma

PURPOSE/OBJECTIVE(S)

Significant heterogeneity exists with regards to prior published reports of re-irradiation (re-RT) in patients with recurrent high grade glioma (HGG). A multi-institutional database of 10 academic centers across the United States was created to analyze prognostic outcomes for re-RT for recurrent HGG, which included WHO Grade III and Grade IV tumors.

MATERIALS/METHODS

Patients with HGG who had initially received standard radiotherapy (RT) and were subsequently treated with a course of re-RT at recurrence were included in the study. Factors assessed to delineate a significant association with overall survival (OS) and toxicity included age, KPS, number of relapses, dose, use of bevacizumab (BEV) or temozolomide (TMZ), time from prior RT, histology, RT target, re-RT target> 5cm and extent of resection, and MGMT methylation status. The Kaplan-Meier Method was used to estimate OS. Cox proportional hazards regression models were used to identify factors associated with OS. Toxicity outcomes were assessed using logistic regression. Significance was assumed if p<0.05. Data management and decision management software were used for all analyses.

RESULTS

Between 2001 and 2022, 280 patients from 10 academic institutions were treated with re-RT for diagnosis of recurrent HGG. 133 patients (71.1%) had a histologic glioblastoma (GBM) at the time of re-RT, with the remainder having Grade 3 gliomas. Median dose delivered at re-RT was 47 Gy BED10 (IQR 47 - 53 Gy BED10), with the most common regimen being 35 Gy in 10 fractions. 83 patients (56%) had GTV greater than 5 cm treated with re-RT. 183 patients (79%) received concurrent systemic therapy, including 95 (41%) who received concurrent TMZ and 86 (45%) who received concurrent BEV. Median OS for the entire cohort was 10 months. Increasing dose at re-RT was associated with improved OS (OR 0.80 95% CI 0.67-0.95, p = 0.10 per 10 Gy BED10), as was dose greater than 47 Gy BED10, which is equivalent to 35 Gy in 10 fractions (OR 0.70, 95% CI 0.54-0.91). Concurrent TMZ was also associated with improved OS (OR 0.68, 95% CI 0.46-0.83, p < 0.01). 32/143 (22%) patients evaluable for toxicity experienced Grade 2 or greater adverse radiation effect (ARE). Use of BEV was associated with decreased toxicity (OR 0.45, 95% CI 0.21-0.98, p = 0.05). Dose at re-RT (OR 1.07 per 10 Gy BED10, p = 0.78), a GTV > 5cm (OR 1.39, p = 0.44), and the use of concurrent TMZ (OR 1.90, p = 0.10) were not associated with Grade 2 or greater ARE.

CONCLUSION

Higher dose of re-RT and use of concurrent TMZ led to improved OS in recurrent HGG patients without an associated increased rate of ARE. Use of BEV decreased the likelihood of Grade 2 or greater ARE in the re-RT setting for these recurrent HGG patients.

Bridging Radiotherapy Prior to Chimeric Antigen Receptor T-Cell Therapy for B-Cell Lymphomas: An ILROG Multi-Institutional Study

PURPOSE/OBJECTIVE(S)

To report an ILROG multi-institutional analysis of bridging radiotherapy (BRT) prior to CD19-targeting chimeric antigen receptor T-cell (CAR T) therapy for relapsed/refractory aggressive B-cell lymphomas (BCL).

MATERIALS/METHODS

Weretrospectively reviewed 115 patients (pts) with diffuse large BCL (n = 101, 88%), primary mediastinal BCL (n = 11, 10%), mantle cell lymphoma (n = 2, 2%), and T-cell/histiocyte rich large BCL (n = 1, 1%) who received BRT prior to commercial CAR T from 2018-2020 across 6 institutions. BRT toxicities were graded per CTCAE v5.0, cytokine release syndrome (CRS) per ASTCT, and immune effector cell-associated neurotoxicity syndrome (ICANS) per either ASTCT or CTCAE v5.0. Progression-free survival (PFS) and overall survival (OS), measured from CAR T infusion, were estimated using the Kaplan-Meier method. PFS was modeled using Cox regression with stepwise variable selection.

RESULTS

BRTwas given prior to axicabtagene ciloleucel (axi-cel; n = 82, 71%), tisagenlecleucel (tisa-cel; n = 31, 27%), or brexucabtagene autoleucel (n = 2, 2%). Median age was 62 years with median of two prior lines of therapy. Most pts had advanced stage III/IV disease at leukapheresis (n = 87, 76%), elevated pre-leukapheresis LDH (n = 73, 63%), and bulky disease (n = 55, 50%) (1 lesion ≥7.5 cm). 78 pts (68%) had extranodal disease, 12 (10%) had central nervous system (CNS) involvement, and 36 (31%) had bone involvement. Systemic bridging therapy was given to 42 pts (37%). Median intervals from leukapheresis to BRT start and from BRT completion to CAR T infusion were 5 days (IQR -6, 11) and 12 days (IQR 9, 23), respectively. BRT was delivered to 163 total sites; most commonly the abdomen/pelvis (n = 58, 50%), head/neck (n = 34, 30%), thorax (n = 20, 17%), extremity/soft tissue (n = 20, 17%), and CNS (n = 13, 11%). Median biologically effective dose was 31.3 Gy (IQR 24, 39). Most common regimen was 30 Gy in 10 fractions (n = 27, 17%). 40 pts (35%) received comprehensive BRT (to all active lesions). There were no grade ≥3 BRT toxicities. Grade ≥3 CRS occurred in 9 pts (8%), including 8/82 (10%) after axi-cel and 1/31 (3%) after tisa-cel. Grade ≥3 ICANS occurred in 23 pts (20%), including 22/82 (27%) after axi-cel and 1/31 (3%) after tisa-cel. Median follow up was 26.9 months. 1- and 2-year OS rates were 60% and 49%. 1- and 2-year PFS rates were 41% and 35%. Comprehensive BRT associated with superior PFS (HR 0.34, 95% CI 0.19-0.62, p<0.001) in a multivariable model with age ≥60, ECOG ≥2, advanced stage, CNS disease, pre-leukapheresis LDH, and axi-cel.

CONCLUSION

In this multi-institutional study, pts receiving BRT prior to CAR T therapy for BCL frequently had bulky disease yet experienced favorable PFS and OS. There were no serious toxicities attributable to BRT, and the rates of CRS and ICANS are comparable to those after CAR T alone. Comprehensive BRT associated with superior PFS.

Identifying Common Topics in Patient Portal Messages with Unsupervised Natural Language Processing

PURPOSE/OBJECTIVE(S)

Patient portal messaging is an increasingly important form of communication between patients and medical providers. This has become particularly relevant in oncology, where patients undergo intense longitudinal treatments that require frequent communication regarding symptoms, appointments, and diagnostic results. The rise in the volume of these messages has significantly increased the workload of medical providers and consequent physician burn-out. Natural language processing (NLP), particularly transformer-based models, may offer an automated approach to characterize the content of patient messages and improve message triage and routing. In this study, we employed a state-of-the-art language model (Bidirectional Encoder Representations from Transformers; BERT) to identify data-derived categories of representative topics from real-world data thereby providing basic information to build an appropriate routing system.

MATERIALS/METHODS

Patient-generated portal messages sent to a messaging pool for a single institution radiation oncology department from 2014 to 2023 were extracted. BERTopic, an NLP-based topic modeling technique based on BERT was optimized for topic modeling of patient messages. Uniform Manifold Approximation and Projection (UMAP) was used to reduce dimensionality and visualize topic relationships across messages. The BERTopic-identified topic categories were subsequently labeled manually by one of the physician investigators. Differences of number of messages over time were assessed using t-tests.

RESULTS

A total of 47,492 messages were retrieved. The average number of messages per month from a single patient ranged from 1 to 18 (median 1.67, interquartile range 1.0-2.4). The total volume of patient messages showed a ten-fold increase over the study period, with 101 messages per month sent in 2014 and 999 messages per month in 2022 (p<0.001). BERTopic initially identified 35 topics whose relationships and degrees of overlap were visualized by UMAP. Due to physician-identified similarities, these topics were reduced into 13 categories. The most frequent topic category was messages about laboratory tests or imaging studies: 24.3%, followed by messages expressing appreciation: 18.9%, scheduling discussions: 15.6%, symptom-related messages: 11%, and treatment-related messages: 10.7%.

CONCLUSION

Patient portal messages sent to a single institution radiation oncology department have increased dramatically in volume since implementation, corresponding to a broader national trend. NLP successfully identified common subject themes across patient messages, many of which are related to scheduling. This presents potential opportunities to apply NLP to automate message routing in the future.

Natural Language Processing Identification of Symptoms in Emergency Department Visits in Patients Receiving Radiation

PURPOSE/OBJECTIVE(S)

Patients undergoing radiotherapy (RT) for cancer often require emergency department (ED) attention with possible hospitalization. Designing strategies to mitigate hospital admissions requires understanding the causal symptoms to tailor interventional strategies. Natural language processing (NLP) has previously been shown to accurately identify documented symptoms and may help characterize factors contributing to admission. The objective of this study was to use NLP to identify documented symptoms during ED visits and their association with subsequent hospital admission of patients undergoing RT.

MATERIALS/METHODS

A de-identified, single tertiary-care institution cohort of patients who received radiation between 2013 and 2022 was identified from the electronic health record using International Classification of Disease (ICD) and Current Procedural Terminology (CPT) codes. We applied a previously validated clinical Text Analysis and Knowledge Extraction System (cTAKES)-based NLP pipeline to extract Common Terminology Criteria for Adverse Events (CTCAE) encoded symptoms from ED encounter clinical notes. Chi-squared testing was used to compare demographics, and logistic regression was used to identify symptoms associated with subsequent admission from ED visits.

RESULTS

We identified 14,007 patients who received radiation, of whom 270 (1.9%) experienced 302 ED visits during their radiation course. 141 (46.7%) of ED visits resulted in an admission. Among patients with an ED encounter, there were no differences in admission rates based on primary language (p = 0.771), sex (p = 0.824), marital status (p = 0.753), race (p = 0.222), or age (p = 0.123). In admitted patients, the top 5 symptoms were pain (94.3%), nausea (92.1%), vomiting (73.7%), constipation (70.9%), and weakness (63.8%). In patients who did not require admission, the most common symptoms were pain (84.5%), nausea (67.1%), vomiting (47.2%), headache (36.6%), and weakness (35.4%). The 10 symptoms most associated with admission from the ED based on logistic regression were malaise (OR 21.7, [95% CI 10.1 - 51.0]), lethargy (19.1, [8.5 - 51.3]), flushing (15.7, [8.6 - 30.4]), agitation (12.4, [3.5 - 78.7]), somnolence (10.3, [4.7 - 25.9]), fall (8.5, [3.7 - 23.2]), fatigue (7.8, [4.6 - 13.4]), constipation (6.9, [4.2 - 11.6]), nausea (5.8, [3.0 - 12.2]), and swelling (5.4, [3.3 - 9.1]).

CONCLUSION

Admitted and non-admitted ED patients with cancer seen in the ED during radiotherapy are documented to experience similar symptoms, but certain symptoms are associated with a higher risk of hospital admission. NLP may offer a mechanism for early, automated identification to facilitate supportive interventions for patients at high risk for admission during radiotherapy.

Adjuvant Chemoradiotherapy within One Year of Resection for Molecularly Defined Astrocytoma

PURPOSE/OBJECTIVE(S)

Treatments for diffuse low-grade gliomas (LGG) are controversial. Level I evidence supports the use of adjuvant radiotherapy (RT) and PCV chemotherapy for histologic LGG, but integration of molecular biomarkers in recent WHO classification and the emergence of temozolomide chemotherapy for gliomas necessitates additional investigation of the optimal treatment and timing of postoperative interventions. We hypothesized molecularly-defined LGG (IDH-mutant astrocytoma (astro) and IDH-mutant, 1p/19q-codeleted oligodendroglioma (oligo)) may have different clinical outcomes following adjuvant RT (aRT) with chemotherapy (aRT+chemo) vs observation or chemo alone.

MATERIALS/METHODS

A retrospective analysis of consecutive adult patients diagnosed with WHO Grade 2 astrocytoma or oligodendroglioma who underwent initial resection at a single institution from January 1998 to November 2017 was performed. Wilcoxon rank sum and Chi-squared tests were used to compare continuous and categorical variables, respectively. Survival analyses were performed using the Kaplan-Meier method and Cox proportional hazards models. Patients without clinical progression or death were censored at the date of last follow-up. Pre-operative and post-operative T2 FLAIR hyperintense tumor volumes were quantified using 3D Slicer to calculate extent of resection (EOR).

RESULTS

A total of 342 patients with molecularly-defined LGG (178 astro, 164 oligo) were identified with a median follow up of 9.1 yr. 171 (50%) patients received RT during their treatment course, of which 31 (18%) were treated with aRT within 1 year of diagnosis. The median aRT dose was 54 Gy (range: 40-60 Gy). aRT was more likely for astro (58%) vs oligo (41%, p = 0.001) and for patients who had resections with lower median EOR (88% vs 95%, p = 0.014). 53 patients (15%) were treated with chemo alone, and 136 patients (40%) were treated with aRT+chemo. Temozolomide was used for 161 patients (85%). For astro, aRT+chemo was associated with longer PFS (median 14.9 yr) compared to observation (4.8 yr, p = 0.05), aRT without chemo (5.2 yr, p = 0.01), or chemo alone (4.7 yr, p = 0.02). For oligo, aRT+chemo was associated with longer PFS (median not reached) compared to aRT without chemo (1.6 yr, p = 0.03), but not when compared to observation (median not reached, p = 0.47), or chemo alone (7.9 yr, p = 0.45). Multivariate analysis showed preoperative tumor volume, EOR, and aRT+chemo (but not aRT or chemo alone) were independently associated with astro PFS compared to observation. Propensity matching based on pre-operative tumor volume, EOR, and age demonstrated longer astro PFS after aRT+chemo (14.9 yr) compared to observation or chemo alone (4.5 yr, p = 0.015), without significant difference in OS (18.2 vs. 11.5 yr, p = 0.40).

CONCLUSION

Retrospective data from a single institution support the use of adjuvant radiotherapy with chemotherapy for patients with molecular astrocytomas, while the role of this approach for oligodendrogliomas is unclear in this cohort.

A Survey of Submission and Review Standards across Clinical Radiation Oncology and Medical Physics Journals: Devising the Optimal Criteria for Reproducibility and Sustained Impact

PURPOSE/OBJECTIVE(S)

Publishing and editorial policies differ substantially across the Radiation Oncology (RO) and Medical Physics (MedPhys) compendium of journals. Adoptance of modern standards in scientific publishing and data sharing have the potential to improve the impact and reliability of the RO literature.

MATERIALS/METHODS

We characterized the editorial, authorship and peer reviewer policies of various prominent clinical RO (N = 16) and medical physics (N = 9) peer-reviewed journals affiliated with professional societies for characteristics that are associated with improved reproducibility and rigorous review. A combination of tools including Enhancing the QUAlity and Transparency Of health Research (EQUATOR), Findability, Accessibility, Interoperability, and Reuse (FAIR), and Quality Output Checklist and Content Assessment (QuOCCA) principles were used to quantify the value and reproducibility of journal policies. Cohen's kappa coefficient was utilized to assess agreement between reviewers. Components of the above tools were regressed against various scientometric indices (H-index, IF, etc.) to identify factors that are associated with perceived relative importance within the field.

RESULTS

Reviewer agreement (κ) for scientometric indices was highest (1.0) for criteria for statistical review and data submission standards and lowest (-0.246) for various submission checklists. Data availability statements were endorsed (44%) or required (31%) in a higher proportion of RO journals relative to MedPhys journals (44%, 0% respectively). Data repository submission was required in <10% of journals. FAIR adoptance was poor (31%, 22%) in RO and MedPhys journals. ≥1 EQUATOR guideline checklist was endorsed or required in 76% of journals. While there were no glaring differences in editorial policies between RO and MedPhys journals, there was substantial heterogeneity of scientometrics evaluating the rigor of data submission, reproducibility standards, and statistical review criteria. Linear regression of journal impact factors indicated a predictive relationship between FAIR adoption standards, use of EQUATOR checklists, and more rigorous statistical method submission criteria.

CONCLUSION

The present review documented and confirmed significant variation in submission, review, and publication policies across RO and MedPhys journals. Established scientometric standards, FAIR principle adoptance, and more rigorous statistical methodology were predictive of increasing journal impact factor.