Assessment of Local and Regional Control in Atypical (WHO Grade 2) Meningiomas Receiving Fractioned Stereotactic Radiotherapy

PURPOSE/OBJECTIVE(S)

The optimal delivery of postoperative radiotherapy to WHO grade 2 or atypical meningiomas (AM) is controversial. The historical standard of care has been high dose fractionated radiation to the resection bed and a 2 cm CTV as in RTOG 0539. Single fraction radiosurgery offers a more conformal alternative with demonstrated local control for smaller AM in less sensitive areas. Though less studied, fractionated stereotactic radiosurgery (FSRT) promises safer treatment of larger AM in more sensitive locations while minimizing the treated volume. This single institution retrospective review examines the hypothesis that local and marginal failure patterns in AM treated with five fraction FSRT remain unacceptably high.

MATERIALS/METHODS

Thirty-nine patients received 27.5 - 30 Gy in 5 fractions to their AM from 2009 to 2022 with grading based on the WHO criteria active at the time of treatment. All treatments were frameless VMAT deliveries with no PTV margin. Histological diagnosis of AM, gross disease at time of FSRT, five fraction FSRT, and lack of prior local radiation were required for inclusion. Single fraction treatments were excluded. Local recurrence was defined similar to RECIST criteria as an increase of 20% in the greatest cross-sectional diameter on MRI (or CT if MRI contraindicated) with at least one voxel touching the prescription volume. To examine the role of CTV margin, marginal recurrence was defined as any new lesion outside of the prescription volume but within 2 cm of the resection cavity. High grade toxicity per CTCAE v5 was an irreversible grade 3 or any grade 4 toxicity. Resection for radionecrosis was considered a local failure if any viable tumor was seen on pathology.

RESULTS

Median follow up was 32.5 months (range 3.2-147.5 months). The number of AM treated post STR, post GTR recurrence, and definitively were 26, 16, and 5 respectively. 3-year local tumor control was estimated to be 84%. As expected, larger tumors were more likely to fail locally (p >.001). Two (5%) patients experienced high grade toxicity - both symptomatic radionecrosis requiring resection. Three-year marginal control was estimated to be 92.3%. Of the 5 tumors treated to the entire resection cavity, none experienced a marginal failure. Interestingly, recurrent tumors s/p GTR were more likely to recur marginally than tumors treated after STR (p = .009). Only 1 (4%) tumor treated after STR failed marginally while 4 (33%) tumors treated after GTR recurrence failed.

CONCLUSION

The rate of high-grade toxicity in AM receiving FSRT was low. Local control appeared comparable to historical rates which may suggest the need for dose escalation with longer term follow-up. Recurrent tumors appear more prone to marginal failures, however more work is needed to determine which patients may benefit from additional CTV margin and more prolonged fractionated dose schedules. Improved targeting with newer imaging studies (e.g., DOTATATE PET) should be examined to determine if more accurate targeting will improve outcomes.

Frameless LINAC-Based Stereotactic Radiosurgery is Safe and Effective for Essential and Parkinsonian Tremor

PURPOSE/OBJECTIVE(S)

Stereotactic radiosurgery (SRS) to the thalamus is an ablative technique used for treatment of refractory tremor of essential or Parkinsonian origin. Because of the high dose, small target, and required precision, framed SRS on the Gamma Knife has been the historical platform of choice. We tested our recently developed technique to emulate GK dose distributions on a multi-leaf collimator (MLC)-equipped linear accelerator (LINAC) without cumbersome, inefficient cones in a prospective trial of safety and efficacy.

MATERIALS/METHODS

We quantified pre-treatment contralateral tremor according to FTM scoring system. We obtained MPRAGE, FGATIR, DTI, and RS-fMRI sequences. We identified the VIM via classical stereotactic reference location and connectomically, and then targeted it to 135 Gy dmax in a manner dosimetrically roughly equivalent to 4 mm GK shot. We adjusted each target such that the 25 Gy isodose line did not overlap the posterior limb of the capsule. We immobilized patients in a highly rigid thermoplastic mask and delivered treatment on an Edge™ LINAC with HDMLC. Intrafraction optical surface monitoring (OSMS) ensured patient immobility. We surveilled post-treatment imaging and recorded tremor scoring, QOL outcomes, and adverse events.

RESULTS

We accrued 42 patients (16 female, 26 males; median age 72.5) over 36 months. 38 had essential tremor, 4 had tremor-dominant Parkinson's; 2 withdrew prior to treatment. Ten patients were on therapeutic anti-coagulation, and were not required to discontinue. At time of submission 39 patients had follow-up ≥ 6 months. 35/39 (89.7%) exhibited clinically meaningful tremor reduction. Mean limb tremor reduction among responders was 43.5% (range: 9 - 100%). Time to patient-reported tremor improvement was 0.3 to 15 months. One patient experienced Gr 3, and 4 patients experienced Gr 1-2 toxicity.

CONCLUSION

MLC-based SRS thalamotomy is safe and effective for refractory tremor treatment. Multidisciplinary management is key for proper patient selection, treatment, and monitoring. Our outcomes appear congruent to historical GK controls as well as more modern MRgFUS outcomes.

Early Clinical Experience of Utilizing Online Adaptive Radiotherapy for Accelerated Partial Breast Irradiation with Stereotactic Body Radiation Therapy for Early-Stage Breast Cancer Patients

PURPOSE/OBJECTIVE(S)

Accelerated partial breast irradiation (APBI) with stereotactic body radiation therapy (SBRT) is becoming popular for early-stage breast cancer (ESBC) due to decreased treatment time and dose to healthy breast tissue. With variability in lumpectomy cavity size post-surgery, CBCT-guided online adaptive RT (oART) may improve target coverage and reduce normal tissue exposure by accounting for inter- and intrafractional cavity variations. In this study, we report our initial clinical experience utilizing APBI oART for patients with ESBC.

MATERIALS/METHODS

A total of 15 patients with 17 ESBC cavities (2 with bilateral disease) were treated with SBRT using oART over one year. Patients were immobilized using standard breast simulation setup with free breathing and breath hold (if left sided). The clinical target volume consisted of an isometric 1 cm expansion off the lumpectomy cavity, which was expanded another 3 mm (cropped 3mm from surface) to create the planning target volume (PTV). 95% of the PTV received prescription dose (30 Gy in 5 fractions). The oART delivery process (supervised by physician and physicist) initially coregisters the daily CBCT to the treatment planning CT with alignment to lumpectomy cavity. Target volumes and organs-at-risk were modified at each treatment and the plan re-optimized. Either the re-optimized oART plan or scheduled plan was chosen for each fraction pending which plan best met prespecified clinical goals. Acute toxicity was assessed at one-month follow-up using CTCAE.

RESULTS

Patients were age 56 or older, ECOG 0-1, with no known genetic abnormality, and with anatomic stage 0-1A ESBC. Most tumors were located in the upper outer quadrant (n = 12, 70.6%) at middle or posterior depth (n = 15, 88.2%). Final margins were negative. 88% had tantalum clips placed. One patient had an Oncotype DS score of 34 and received systemic therapy. 82.3% met suitable APBI criteria and 3 met cautionary criteria due to high grade, of which 2 had ipsilateral trimodality treatment 10+ years prior and denied mastectomy at recurrence. Mean time to starting RT after lumpectomy was 2.5 months. Mean PTV to breast ratio was 0.12. From simulation to end of treatment, lumpectomy cavity size decreased a median of 27%. oART plans were chosen 89% of the time. VMAT was utilized 52.9% of the time compared to static-field IMRT (47.1%). Three patients were treated with breath hold. 93% of patients were treated on non-consecutive days with average treatment lasting 9.1 ± 2.2 days. CTCAE grade 1 toxicities were hyperpigmentation (n = 6, 40%), breast pain (n = 2, 13.3%), persistent seroma (n = 1, 6.7%), and fatigue (n = 7, 46.7%). No patients experienced fat necrosis, telangiectasias, breast shrinkage, lymphedema, or CTCAE grade 2+ toxicities.

CONCLUSION

oART for APBI using SBRT for patients with ESBC is clinically feasible and allows for variations in lumpectomy cavity size. Nearly half of patients had no complaints or breast changes at one-month follow-up and the remaining had CTCAE grade 1 toxicities alone.

Occurrence of Neonatal Necrotizing Enterocolitis in Premature Neonates and Gut Microbiota: A Case-Control Prospective Multicenter Study

BACKGROUND

Necrotizing enterocolitis (NEC) is still one of the leading causes of neonatal death. The present study reports the data from a French case-control prospective multicenter study.

METHODS

A total of 146 preterm neonates (PNs) with or without NEC were included. Bacterial 16S rRNA gene sequencing was performed on stool samples (n = 103). Specific culture media were used to isolate Escherichia coli, Clostridium butyricum, and Clostridium neonatale, and strains were phenotypically characterized.

RESULTS

The gut microbiota of PNs was dominated by Firmicutes and Proteobacteria, and five enterotypes were identified. The microbiota composition was similar between NEC cases and PN controls. However, differences were observed in the relative abundance of Lactobacillus genus, which was significantly lower in the NEC group, whereas that of the Clostridium cluster III was significantly higher (p < 0.05). Within enterotypes, several phylotypes were significantly more abundant in NEC cases (p < 0.05). Regarding perinatal factors, a statistical association was found between the gut microbiota and cesarean delivery and antifungal therapy. In NEC cases and PN controls, the carriage rates and virulence genes of uropathogenic E. coli were equivalent based on culture. No correlation was found between E. coli, C. butyricum, and C. neonatale carriages, beta-lactam resistance, and antibiotic treatment.

CONCLUSIONS

At disease onset, our data support a microbiota dysbiosis between NEC and control infants at the genus level. In addition, it provides valuable information on bacterial antimicrobial susceptibility.

Circulating T cell profiles associate with enterotype signatures underlying hematological malignancy relapses

Early administration of azithromycin after allogeneic hematopoietic stem cell transplantation was shown to increase the relapse of hematological malignancies. To determine the impact of azithromycin on the post-transplant gut ecosystem and its influence on relapse, we characterized overtime gut bacteriome, virome, and metabolome of 55 patients treated with azithromycin or a placebo. We describe four enterotypes and the network of associated bacteriophage species and metabolic pathways. One enterotype associates with sustained remission. One taxon from Bacteroides specifically associates with relapse, while two from Bacteroides and Prevotella correlate with complete remission. These taxa are associated with lipid, pentose, and branched-chain amino acid metabolic pathways and several bacteriophage species. Enterotypes and taxa associate with exhausted T cells and the functional status of circulating immune cells. These results illustrate how an antibiotic influences a complex network of gut bacteria, viruses, and metabolites and may promote cancer relapse through modifications of immune cells.

Adlercreutzia equolifaciens Is an Anti-Inflammatory Commensal Bacterium with Decreased Abundance in Gut Microbiota of Patients with Metabolic Liver Disease

Non-alcoholic fatty liver disease (NAFLD) affects about 20-40% of the adult population in high-income countries and is now a leading indication for liver transplantation and can lead to hepatocellular carcinoma. The link between gut microbiota dysbiosis and NAFLD is now clearly established. Through analyses of the gut microbiota with shotgun metagenomics, we observe that compared to healthy controls, Adlercreutzia equolifaciens is depleted in patients with liver diseases such as NAFLD. Its abundance also decreases as the disease progresses and eventually disappears in the last stages indicating a strong association with disease severity. Moreover, we show that A. equolifaciens possesses anti-inflammatory properties, both in vitro and in vivo in a humanized mouse model of NAFLD. Therefore, our results demonstrate a link between NAFLD and the severity of liver disease and the presence of A. equolifaciens and its anti-inflammatory actions. Counterbalancing dysbiosis with this bacterium may be a promising live biotherapeutic strategy for liver diseases.

Connectomic Basis for Tremor Control in Stereotactic Radiosurgical Thalamotomy

BACKGROUND AND PURPOSE

Given the increased use of stereotactic radiosurgical thalamotomy and other ablative therapies for tremor, new biomarkers are needed to improve outcomes. Using resting-state fMRI and MR tractography, we hypothesized that a "connectome fingerprint" can predict tremor outcomes and potentially serve as a targeting biomarker for stereotactic radiosurgical thalamotomy.

MATERIALS AND METHODS

We evaluated 27 patients who underwent unilateral stereotactic radiosurgical thalamotomy for essential tremor or tremor-predominant Parkinson disease. Percentage postoperative improvement in the contralateral limb Fahn-Tolosa-Marin Clinical Tremor Rating Scale (TRS) was the primary end point. Connectome-style resting-state fMRI and MR tractography were performed before stereotactic radiosurgery. Using the final lesion volume as a seed, "connectivity fingerprints" representing ideal connectivity maps were generated as whole-brain R-maps using a voxelwise nonparametric Spearman correlation. A leave-one-out cross-validation was performed using the generated R-maps.

RESULTS

The mean improvement in the contralateral tremor score was 55.1% (SD, 38.9%) at a mean follow-up of 10.0 (SD, 5.0) months. Structural connectivity correlated with contralateral TRS improvement (r = 0.52; P  = .006) and explained 27.0% of the variance in outcome. Functional connectivity correlated with contralateral TRS improvement (r = 0.50; P  = .008) and explained 25.0% of the variance in outcome. Nodes most correlated with tremor improvement corresponded to areas of known network dysfunction in tremor, including the cerebello-thalamo-cortical pathway and the primary and extrastriate visual cortices.

CONCLUSIONS

Stereotactic radiosurgical targets with a distinct connectivity profile predict improvement in tremor after treatment. Such connectomic fingerprints show promise for developing patient-specific biomarkers to guide therapy with stereotactic radiosurgical thalamotomy.

Modulation of the microbiota by oral antibiotics treats immunoglobulin A nephropathy in humanized mice

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. IgA is mainly produced by the gut-associated lymphoid tissue (GALT). Both experimental and clinical data suggest a role of the gut microbiota in this disease. We aimed to determine if an intervention targeting the gut microbiota could impact the development of disease in a humanized mouse model of IgAN, the α1KI-CD89Tg mice.

METHODS

Four- and 12-week old mice were divided into two groups to receive either antibiotics or vehicle control. Faecal bacterial load and proteinuria were quantified both at the beginning and at the end of the experiment, when blood, kidneys and intestinal tissue were collected. Serum mouse immunoglobulin G (mIgG) and human immunoglobulin A1 (hIgA1)-containing complexes were quantified. Renal and intestinal tissue were analysed by optical microscopy after haematoxylin and eosin colouration and immunohistochemistry with anti-hIgA and anti-mouse CD11b antibodies.

RESULTS

Antibiotic treatment efficiently depleted the faecal microbiota, impaired GALT architecture and impacted mouse IgA production. However, while hIgA1 and mIgG serum levels were unchanged, the antibiotic treatment markedly prevented hIgA1 mesangial deposition, glomerular inflammation and the development of proteinuria. This was associated with a significant decrease in circulating hIgA1-mIgG complexes. Notably, final faecal bacterial load strongly correlated with critical clinical and pathophysiological features of IgAN such as proteinuria and hIgA1-mIgG complexes. In addition, treatment with broad-spectrum antibiotics reverted established disease.

CONCLUSIONS

These data support an essential role of the gut microbiota in the generation of mucosa-derived nephrotoxic IgA1 and in IgAN development, opening new avenues for therapeutic approaches in this disease.