Technical feasibility of novel immunostimulatory low-dose radiation for polymetastatic disease with CBCT-based online adaptive and conventional approaches

PURPOSE

A workflow/planning strategy delivering low-dose radiation therapy (LDRT) (1 Gy) to all polymetastatic diseases using conventional planning/delivery (Raystation/Halcyon = "conventional") and the AI-based Ethos online adaptive RT (oART) platform is developed/evaluated.

METHODS

Using retrospective data for ten polymetastatic non-small cell lung cancer patients (5-52 lesions each) with PET/CTs, gross tumor volumes (GTVs) were delineated using PET standardized-uptake-value (SUV) thresholding. A 1 cm uniform expansion of GTVs to account for setup/contour uncertainty and organ motion-generated planning target volumes (PTVs). Dose optimization/calculation used the diagnostic CT from PET/CT. Dosimetric objectives were: Dmin,0.03cc ≥ 95% (acceptable variation (Δ) ≥ 90%), V100% ≥ 95% (Δ ≥ 90%), and D0.03cc ≤ 120% (Δ ≤ 125%). Additionally, online adaptation was simulated. When available, subsequent diagnostic CT was used to represent on-treatment CBCT. Otherwise, the CT from PET/CT used for initial planning was deformed to simulate clinically representative changes.

RESULTS

All initial plans generated, both for Raystation and Ethos, achieved clinical goals within acceptable variation. For all patients, Dmin,0.03cc ≥ 95%, V100% ≥ 95%, and D0.03cc ≤ 120% goals were achieved for 84.8%/99.5%, 97.7%/98.7%, 97.4%/92.3%, in conventional/Ethos plans, respectively. The ratio of 50% isodose volume to PTV volume (R50% ), maximum dose at 2 cm from PTV (D2cm ), and the ratio of the 100% isodose volume to PTV volume (conformity index) in Raystation/Ethos plans were 7.9/5.9; 102.3%/88.44%; and 0.99/1.01, respectively. In Ethos, online adapted plans maintained PTV coverage whereas scheduled plans often resulted in geographic misses due to changes in tumor size, patient position, and body habitus. The average total duration of the oART workflow was 26:15 (min:sec) ranging from 6:43 to 57:30. The duration of each oART workflow step as a function of a number of targets showed a low correlation coefficient for influencer generation and editing (R2  = 0.04 and 0.02, respectively) and high correlation coefficient for target generation, target editing and plan generation (R2  = 0.68, 0.63 and 0.69, respectively).

CONCLUSIONS

This study demonstrates feasibility of conventional planning/treatment with Raystation/Halcyon and highlights efficiency gains when utilizing semi-automated planning/online-adaptive treatment with Ethos for immunostimulatory LDRT conformally delivered to all sites of polymetastatic disease.

Deep Learning-Guided Dosimetry for Mitigating Local Failure of Patients With Non-Small Cell Lung Cancer Receiving Stereotactic Body Radiation Therapy

PURPOSE

Non-small cell lung cancer (NSCLC) stereotactic body radiation therapy with 50 Gy/5 fractions is sometimes considered controversial, as the nominal biologically effective dose (BED) of 100 Gy is felt by some to be insufficient for long-term local control of some lesions. In this study, we analyzed such patients using explainable deep learning techniques and consequently proposed appropriate treatment planning criteria. These novel criteria could help planners achieve optimized treatment plans for maximal local control.

METHODS AND MATERIALS

A total of 535 patients treated with 50 Gy/5 fractions were used to develop a novel deep learning local response model. A multimodality approach, incorporating computed tomography images, 3-dimensional dose distribution, and patient demographics, combined with a discrete-time survival model, was applied to predict time to failure and the probability of local control. Subsequently, an integrated gradient-weighted class activation mapping method was used to identify the most significant dose-volume metrics predictive of local failure and their optimal cut-points.

RESULTS

The model was cross-validated, showing an acceptable performance (c-index: 0.72, 95% CI, 0.68-0.75); the testing c-index was 0.69. The model's spatial attention was concentrated mostly in the tumors' periphery (planning target volume [PTV] - internal gross target volume [IGTV]) region. Statistically significant dose-volume metrics in improved local control were BED Dnear-min ≥ 103.8 Gy in IGTV (hazard ratio [HR], 0.31; 95% CI, 015-0.63), V104 ≥ 98% in IGTV (HR, 0.30; 95% CI, 0.15-0.60), gEUD ≥ 103.8 Gy in PTV-IGTV (HR, 0.25; 95% CI, 0.12-0.50), and Dmean ≥ 104.5 Gy in PTV-IGTV (HR, 0.25; 95% CI, 0.12-0.51).

CONCLUSIONS

Deep learning-identified dose-volume metrics have shown significant prognostic power (log-rank, P = .003) and could be used as additional actionable criteria for treatment planning in NSCLC stereotactic body radiation therapy patients receiving 50 Gy in 5 fractions. Although our data do not confirm or refute that a significantly higher BED for the prescription dose is necessary for tumor control in NSCLC, it might be clinically effective to escalate the nominal prescribed dose from BED 100 to 105 Gy.

Targeting intracellular oncoproteins with dimeric IgA promotes expulsion from the cytoplasm and immune-mediated control of epithelial cancers

Dimeric IgA (dIgA) can move through cells via the IgA/IgM polymeric immunoglobulin receptor (PIGR), which is expressed mainly on mucosal epithelia. Here, we studied the ability of dIgA to target commonly mutated cytoplasmic oncodrivers. Mutation-specific dIgA, but not IgG, neutralized KRASG12D within ovarian carcinoma cells and expelled this oncodriver from tumor cells. dIgA binding changed endosomal trafficking of KRASG12D from accumulation in recycling endosomes to aggregation in the early/late endosomes through which dIgA transcytoses. dIgA targeting of KRASG12D abrogated tumor cell proliferation in cell culture assays. In vivo, KRASG12D-specific dIgA1 limited the growth of KRASG12D-mutated ovarian and lung carcinomas in a manner dependent on CD8+ T cells. dIgA specific for IDH1R132H reduced colon cancer growth, demonstrating effective targeting of a cytoplasmic oncodriver not associated with surface receptors. dIgA targeting of KRASG12D restricted tumor growth more effectively than small-molecule KRASG12D inhibitors, supporting the potential of this approach for the treatment of human cancers.

Novel Dose Criteria for Lung Cancer SBRT to Improve Local Control in Patients Treated to 50 Gy/5 Fractions Using Deep Learning Methods and Explainability Techniques

PURPOSE/OBJECTIVE(S)

To some radiation oncologists, 50 Gy/5 fractions has been considered controversial, as they feel the nominal BED of 100 Gy might be too low for long-term local control of some lesions. We analyzed a large cohort of these patients using a deep learning model to predict local recurrence (LR) and used explainability techniques to extract new dose features important to the model's prediction. Subsequently, we determined optimal cut-points for the most significant metrics to provide actionable criteria for treatment planning in these patients.

MATERIALS/METHODS

A total of 535 SBRT lung cancer patients treated between 2009 and 2017 were retrospectively analyzed using a deep learning approach. All patients had NSCLC and all of them were treated with 50 Gy in 5 fractions (100 Gy BED, α/β = 10). Mean clinical maximum tumor diameter was 2.2 cm. There were 31 LR in the dataset with mean follow-up time of 28 months. Mean age was 75 years. CT images, 3D dose distribution and patient demographic details were used to train a deep learning survival model to predict time to failure and probability of local control. Validation, training, and testing were in accordance with TRIPOD criteria. 80 % of the data were used for 5-fold cross-validation (10 iterations) and 20 % was held for independent testing. The Grad-CAM method was applied to identify regions of the dose distribution that are the most significant to the model's decision-making. Based on the results, appropriate dose metrics were proposed, and optimal cut-points were determined to distinguish between lower and higher LR-risk patients.

RESULTS

The model has an acceptable performance (c-index: 0.72, 95% CI: 0.68-0.75); the testing c-index was 0.69. Grad-CAM showed that the model's spatial attention was mostly concentrated in the tumor's "PTV-GTV" region. Statistically significant criteria are in Table 1.

CONCLUSION

A novel deep learning model for prediction of LR, incorporating 3D dose data, CT images and patient demographics, was developed and tested. Grad-CAM demonstrated superior significance of peripheral (PTV-GTV) dose features. Subsequently determined optimal cut-points have significant prognostic power (log rank, p<0.001) and could be used as additional criteria in treatment planning. While these data have repercussions in treatment planning, they do not suggest that a significantly higher BED for the prescription dose is necessary for tumor control in NSCLC. Nevertheless, it might be effective to slightly elevate the prescribed dose, i.e., from 100 Gy BED to 104 Gy BED.

Outcomes of Cytoreductive Stereotactic Body Radiotherapy (SBRT) in Patients with Oligometastatic or Oligoprogressive Dominant Lung Metastases from Colorectal Primary

PURPOSE/OBJECTIVE(S)

Oxaliplatin based systemic therapy regimens have improved the prognosis of patients with colorectal cancer (CRC) and with this, there has been increased interest in the integration of local therapies to oligometastatic and oligoprogressive sites. There is a vast body of literature exploring the benefits of cytoreduction with surgery and stereotactic body radiation therapy (SBRT) approaches. We report our rates of local control (LC) and overall survival (OS) for patients with oligometastatic/progressive CRC with lung metastases treated with SBRT.

MATERIALS/METHODS

Single institution retrospective review of patients diagnosed with oligometastatic or oligoprogressive CRC with dominant metastases to the lungs who were treated with SBRT between September 2009 and December 2022. Oligometastatic disease was defined as newly diagnosed, untreated CRC with up to 5 metastases, up to 3 in one organ. Oligoprogressive disease was defined as CRC with 1 - 2 distant sites that continued to progress on active treatment while the primary site was controlled. Survival was estimated using Kaplan-Meier. Association between local control and patient factors was analyzed using log-rank test.

RESULTS

A total of 84 patients with oligometastatic or oligoprogressive CRC were treated with SBRT to 124 lung lesions. Colon cancer was the primary site for 54 patients with a median age at time of SBRT of 66 years (IQR 57 - 73) and a median tumor diameter of 1.20 cm (IQR 0.93 - 1.90). Rectal cancer was the primary site for 30 patients, median age was 60 years (IQR 49 - 70) and median tumor diameter was 1.10 cm (IQR 0.80 - 1.48). Median dose for the entire cohort was 6000 cGy (range 5000 - 6000) with median number of fractions 5 (range 3 - 5). Median follow-up after SBRT was 24 months. Overall, there were 9 local failures at last follow-up. Almost half (n = 42) of the patients experienced distant recurrence. Median local control (LC) for the entire cohort was not reached, 2-yr LC and 5-yr LC were 94.6% and 85.7% respectively. There were no differences in LC between colon and rectal cancer (p = 0.29). Actuarial median overall survival was 71 months (95% CI 44.3 - 97.7) and 5-yr OS was 50.2%. Due to the small number of events, we were unable to identify patient factors associated with local failure on univariate or multivariate analysis.

CONCLUSION

Cytoreductive SBRT is an effective treatment option for patients with oligometastatic or oligoprogressive CRC with dominant lung metastases offering excellent rates of LC. Most patients failed distantly highlighting the importance of additional systemic therapies.

Upfront Osimertinib Alone vs. Osimertinib and Radiotherapy for the Treatment of EGFR-Positive NSCLC Brain Metastases: A Multi-Institutional Series

PURPOSE/OBJECTIVE(S)

Given the increased brain penetrance of osimertinib, the role of upfront radiotherapy (RT) has been questioned for the management of patients with EGFR+ NSCLC brain metastases (BM). We conducted a multi-institutional review of patients with EGFR+ NSCLC treated with upfront osimertinib or osimertinib in combination with RT for new or progressing BM.

MATERIALS/METHODS

Our multi-institutional analysis included 128 patients with 714 BM treated between 2013 and 2022. Two BM treatment groups were evaluated: (1) upfront osimertinib alone (n = 66) and (2) osimertinib + RT [whole brain radiation therapy or stereotactic/fractionated radiosurgery (SRS/FSRT)] prior or concurrently with osimertinib (n = 62)]; both groups began treatment within 2 months of BM diagnosis. Time-to-event analysis was conducted with the Kaplan-Meier (KM) method, and outcomes included intracranial control (IC) [both local and distant], intracranial progression free survival (IPFS), and overall survival (OS). A Cox proportional hazards model was utilized for multivariate analysis (MVA).

RESULTS

Median follow-up from BM diagnosis was 33.9 months (0.13-76.2 months). No differences in age (p = 0.46), sex (p = 0.72), DS-GPA (p = 0.08), KPS (p = 0.57), number of BM (p = 0.19) or volume of BM (p = 0.45), RT dose (p = 0.45), number of systemic metastases (p = 0.88), and patients symptomatic at presentation (p = 1.0) were noted. Prior treatment of BM was more common in the osimertinib + RT group (50% osimertinib + RT and 27% osimertinib; p = 0.01). The 12-month KM rates for osimertinib vs osimertinib + RT groups for IC were 72% vs 73% (p = 0.33); IPFS 53% vs 66% (p = 0.007); and OS 65% vs 80% (p = 0.025). On MVA, higher KPS (p = 0.002) was associated with increased OS and no extracranial metastasis with increased OS (p = 0.01) and IPFS (p = 0.001). MVA showed no association between osimertinib vs osimertinib + RT for IC, IPFS, or OS. Of the 66 patients treated with upfront osimertinib, 18 patients (27%) with 31 lesions eventually required RT for intracranial progression with the majority 72% being treated with SRS/FSRT at median of 13.5 months (1-22 months) following the start of osimertinib.

CONCLUSION

This study suggests that upfront osimertinib alone may provide sufficient intracranial control to allow RT to be deferred until further intracranial progression in select patients. Prospective trials are warranted to further guide treatment.

Treatment of Oligometastatic Non-Small Cell Lung Cancer: An ASTRO/ESTRO Clinical Practice Guideline

PURPOSE

This joint guideline by American Society for Radiation Oncology (ASTRO) and the European Society for Radiotherapy and Oncology (ESTRO) was initiated to review evidence and provide recommendations regarding the use of local therapy in the management of extracranial oligometastatic non-small cell lung cancer (NSCLC). Local therapy is defined as the comprehensive treatment of all known cancer-primary tumor, regional nodal metastases, and metastases-with definitive intent.

METHODS

ASTRO and ESTRO convened a task force to address 5 key questions focused on the use of local (radiation, surgery, other ablative methods) and systemic therapy in the management of oligometastatic NSCLC. The questions address clinical scenarios for using local therapy, sequencing and timing when integrating local with systemic therapies, radiation techniques critical for oligometastatic disease targeting and treatment delivery, and the role of local therapy for oligoprogression or recurrent disease. Recommendations were based on a systematic literature review and created using ASTRO guidelines methodology.

RESULTS

Based on the lack of significant randomized phase 3 trials, a patient-centered, multidisciplinary approach was strongly recommended for all decision-making regarding potential treatment. Integration of definitive local therapy was only relevant if technically feasible and clinically safe to all disease sites, defined as 5 or fewer distinct sites. Conditional recommendations were given for definitive local therapies in synchronous, metachronous, oligopersistent, and oligoprogressive conditions for extracranial disease. Radiation and surgery were the only primary definitive local therapy modalities recommended for use in the management of patients with oligometastatic disease, with indications provided for choosing one over the other. Sequencing recommendations were provided for systemic and local therapy integration. Finally, multiple recommendations were provided for the optimal technical use of hypofractionated radiation or stereotactic body radiation therapy as definitive local therapy, including dose and fractionation.

CONCLUSIONS

Presently, data regarding clinical benefits of local therapy on overall and other survival outcomes is still sparse for oligometastatic NSCLC. However, with rapidly evolving data being generated supporting local therapy in oligometastatic NSCLC, this guideline attempted to frame recommendations as a function of the quality of data available to make decisions in a multidisciplinary approach incorporating patient goals and tolerances.

Early-Stage Primary Lung Neuroendocrine Tumors Treated With Stereotactic Body Radiation Therapy: A Multi-Institution Experience

PURPOSE

Current guidelines recommend surgery as standard of care for primary lung neuroendocrine tumor (LNET). Given that LNET is a rare clinical entity, there is a lack of literature regarding treatment of LNET with stereotactic body radiation therapy (SBRT). We hypothesized that SBRT could lead to effective locoregional tumor control and long-term outcomes.

METHODS AND MATERIALS

We retrospectively reviewed 48 tumors in 46 patients from 11 institutions with a histologically confirmed diagnosis of LNET, treated with primary radiation therapy. Data were collected for patients treated nonoperatively with primary radiation therapy between 2006 and 2020. Patient records were reviewed for lesion characteristics and clinical risk factors. Kaplan-Meier analysis, log-rank tests, and Cox multivariate models were used to compare outcomes.

RESULTS

Median age at treatment was 71 years and mean tumor size was 2 cm. Thirty-two lesions were typical carcinoid histology, 7 were atypical, and 9 were indeterminate. The most common SBRT fractionation schedule was 50 to 60 Gy in 5 daily fractions. Overall survival at 3, 6, and 9 years was 64%, 43%, and 26%, respectively. Progression-free survival at 3, 6, and 9 years was 88%, 78%, and 78%, respectively. Local control at 3, 6, and 9 years was 97%, 91%, and 91%, respectively. There was 1 regional recurrence in a paraesophageal lymph node. No grade 3 or higher toxicity was identified.

CONCLUSIONS

This is the largest series evaluating outcomes in patients with LNET treated with SBRT. This treatment is well tolerated, provides excellent locoregional control, and should be offered as an alternative to surgical resection for patients with early-stage LNET, particularly those who may not be ideal surgical candidates.

Anti-4-1BB immunotherapy enhances systemic immune effects of radiotherapy to induce B and T cell-dependent anti-tumor immune activation and improve tumor control at unirradiated sites

Radiation therapy (RT) can prime and boost systemic anti-tumor effects via STING activation, resulting in enhanced tumor antigen presentation and antigen recognition by T cells. It is increasingly recognized that optimal anti-tumor immune responses benefit from coordinated cellular (T cell) and humoral (B cell) responses. However, the nature and functional relevance of the RT-induced immune response are controversial, beyond STING signaling, and agonistic interventions are lacking. Here, we show that B and CD4+ T cell accumulation at tumor beds in response to RT precedes the arrival of CD8+ T cells, and both cell types are absolutely required for abrogated tumor growth in non-irradiated tumors. Further, RT induces increased expression of 4-1BB (CD137) in both T and B cells; both in preclinical models and in a cohort of patients with small cell lung cancer treated with thoracic RT. Accordingly, the combination of RT and anti-41BB therapy leads to increased immune cell infiltration in the tumor microenvironment and significant abscopal effects. Thus, 4-1BB therapy enhances radiation-induced tumor-specific immune responses via coordinated B and T cell responses, thereby preventing malignant progression at unirradiated tumor sites. These findings provide a rationale for combining RT and 4-1bb therapy in future clinical trials.

Methodology for computed tomography characterization of commercially available 3D printing materials for use in radiology/radiation oncology

3D printing in medical physics provides opportunities for creating patient-specific treatment devices and in-house fabrication of imaging/dosimetry phantoms. This study characterizes several commercial fused deposition 3D printing materials with some containing nonstandard compositions. It is important to explore their similarities to human tissues and other materials encountered in patients. Uniform cylinders with infill from 50 to 100% at six evenly distributed intervals were printed using 13 different filaments. A novel approach rotating infill angle 10^o between each layer avoids unwanted patterns. Five materials contained high-Z/metallic components. A clinical CT scanner with a range of tube potentials (70, 80, 100, 120, 140 kVp) was used. Density and average Hounsfield unit (HU) were measured. A commercial GAMMEX phantom mimicking various human tissues provides a comparison. Utility of the lookup tables produced is demonstrated. A methodology for calibrating print materials/parameters for a desired HU is presented. Density and HU were determined for all materials as a function of tube voltage (kVp) and infill percentage. The range of HU (-732.0-10047.4 HU) and physical densities (0.36-3.52 g/cm³ ) encompassed most tissues/materials encountered in radiology/radiotherapy applications with many overlapping those of human tissues. Printing filaments doped with high-Z materials demonstrated increased attenuation due to the photoelectric effect with decreased kVp, as found in certain endogenous materials (e.g., bone). HU was faithfully reproduced (within one standard deviation) in a 3D-printed mimic of a commercial anthropomorphic phantom section. Characterization of commercially available 3D print materials facilitates custom object fabrication for use in radiology and radiation oncology, including human tissue and common exogenous implant mimics. This allows for cost reduction and increased flexibility to fabricate novel phantoms or patient-specific devices imaging and dosimetry purposes. A formalism for calibrating to specific CT scanner, printer, and filament type/batch is presented. Utility is demonstrated by printing a commercial anthropomorphic phantom copy.

Combination IFNβ and Membrane-Stable CD40L Maximize Tumor Dendritic Cell Activation and Lymph Node Trafficking to Elicit Systemic T-cell Immunity

Oncolytic virus therapies induce the direct killing of tumor cells and activation of conventional dendritic cells (cDC); however, cDC activation has not been optimized with current therapies. We evaluated the adenoviral delivery of engineered membrane-stable CD40L (MEM40) and IFNβ to locally activate cDCs in mouse tumor models. Combined tumor MEM40 and IFNβ expression induced the highest cDC activation coupled with increased lymph node migration, increased systemic antitumor CD8+ T-cell responses, and regression of established tumors in a cDC1-dependent manner. MEM40 + IFNβ combined with checkpoint inhibitors led to effective control of distant tumors and lung metastases. An oncolytic adenovirus (MEM-288) expressing MEM40 + IFNβ  in phase I clinical testing induced cancer cell loss concomitant with enhanced T-cell infiltration and increased systemic presence of tumor T-cell clonotypes in non-small cell lung cancer (NSCLC) patients. This approach to simultaneously target two major DC-activating pathways has the potential to significantly affect the solid tumor immunotherapy landscape.

MR-Guided SBRT/Hypofractionated RT for Metastatic and Primary Central and Ultracentral Lung Lesions

Introduction

The recent results from the Nordic-HILUS study indicate stereotactic body radiation therapy (SBRT) is associated with high-grade toxicity for ultracentral (UC) tumors. We hypothesized that magnetic resonance-guided SBRT (MRgSBRT) or hypofractionated radiation therapy (MRgHRT) enables the safe delivery of high-dose radiation to central and UC lung lesions.

Methods

Patients with UC or central lesions were treated with MRgSBRT/MRgHRT with real-time gating or adaptation. Central lesions were defined as per the Radiation Therapy Oncology Group and UC as per the HILUS study definitions: (1) group A or tumors less than 1 cm from the trachea and/or mainstem bronchi; or (2) group B or tumors less than 1 cm from the lobar bronchi. The Kaplan-Meier estimate and log-rank test were used to estimate survival. Associations between toxicities and other patient factors were tested using the Mann-Whitney U test and Fisher's exact test.

Results

A total of 47 patients were included with a median follow-up of 22.9 months (95% confidence interval: 16.4-29.4). Most (53%) had metastatic disease. All patients had central lesions and 55.3% (n = 26) had UC group A. The median distance from the proximal bronchial tree was 6.0 mm (range: 0.0-19.0 mm). The median biologically equivalent dose (α/β = 10) was 105 Gy (range: 75-151.2). The most common radiation schedule was 60 Gy in eight fractions (40.4%). Most (55%) had previous systemic therapy, 32% had immunotherapy and 23.4% had previous thoracic radiation therapy. There were 16 patients who underwent daily adaptation. The 1-year overall survival was 82% (median = not reached), local control 87% (median = not reached), and progression-free survival 54% (median = 15.1 mo, 95% confidence interval: 5.1-25.1). Acute toxicity included grade 1 (26%) and grade 2 (21%) with only two patients experiencing grade 3 (4.3%) in the long term. No grade 4 or 5 toxicities were seen.

Conclusions

Previous studies noted high rates of toxicity after SBRT to central and UC lung lesions, with reports of grade 5 toxicities. In our cohort, the use of MRgSBRT/MRgHRT with high biologically effective doses was well tolerated, with two grade 3 toxicities and no grade 4/5.

Clinical outcomes of non-small cell lung cancer brain metastases treated with stereotactic radiosurgery and immune checkpoint inhibitors, EGFR tyrosine kinase inhibitors, chemotherapy and immune checkpoint inhibitors, or chemotherapy alone

OBJECTIVE

Immune checkpoint inhibitors (ICIs) and epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are commonly used in the systemic management of non-small cell lung cancer (NSCLC) brain metastases (BMs). However, optimizing control of NSCLC BM with stereotactic radiosurgery (SRS) and various systemic therapies remains an area of investigation.

METHODS

Between 2016 and 2019, the authors identified 171 NSCLC BM patients with 646 BMs treated with single-fraction SRS within 3 months of receiving treatment with ICIs (n = 56; 33%), EGFR-TKI (n = 30; 18%), chemotherapy and ICIs (n = 23; 14%), or standard chemotherapy alone (n = 62; 36%). Time-to-event analysis was conducted, and outcomes included distant intracranial control (DIC), local control (LC), and overall survival from SRS.

RESULTS

The median follow-up from BM diagnosis was 8.9 months (range 0.3-127 months). The 12-month Kaplan-Meier DIC rates were 37%, 53%, 41%, and 21% (p = 0.047) for the ICI, EGFR-TKI, ICI and chemotherapy, and chemotherapy-alone groups, respectively. On multivariate analysis, DIC was improved with EGFR-TKI (HR 0.4, 95% CI 0.3-0.8, p = 0.005) compared with conventional chemotherapy and treatment with SRS before systemic therapy (HR 0.5, 95% CI 0.3-0.9, p = 0.03) compared with after; and LC was improved with SRS before (HR 0.4, 95% CI 0.2-0.9, p = 0.03) or concurrently (HR 0.3, 95% CI 0.1-0.6, p = 0.003) compared with after. No differences in radionecrosis were noted by timing or type of systemic therapy.

CONCLUSIONS

The authors' analysis showed significant differences in DIC based on receipt of systemic therapy and treatment with SRS before systemic therapy improved DIC. Prospective evaluation of the potential synergism between systemic therapy and SRS in NSCLC BM management is warranted.

Combined nivolumab and ipilimumab with or without stereotactic body radiation therapy for advanced Merkel cell carcinoma: a randomised, open label, phase 2 trial

BACKGROUND

Merkel cell carcinoma is among the most aggressive and lethal of primary skin cancers, with a high rate of distant metastasis. Anti-programmed death receptor 1 (anti-PD-1) and programmed death ligand 1 (PD-L1) monotherapy is currently standard of care for unresectable, recurrent, or metastatic Merkel cell carcinoma. We assessed treatment with combined nivolumab plus ipilimumab, with or without stereotactic body radiotherapy (SBRT) in patients with advanced Merkel cell carcinoma as a first-line therapy or following previous treatment with anti-PD-1 and PD-L1 monotherapy.

METHODS

In this randomised, open label, phase 2 trial, we randomly assigned adults from two cancer sites in the USA (one in Florida and one in Ohio) to group A (combined nivolumab and ipilimumab) or group B (combined nivolumab and ipilimumab plus SBRT) in a 1:1 ratio. Eligible patients were aged at least 18 years with histologically proven advanced stage (unresectable, recurrent, or stage IV) Merkel cell carcinoma, a minimum of two tumour lesions measureable by CT, MRI or clinical exam, and tumour tissue available for exploratory biomarker analysis. Patients were stratified by previous immune-checkpoint inhibitor (ICI) status to receive nivolumab 240 mg intravenously every 2 weeks plus ipilimumab 1 mg/kg intravenously every 6 weeks (group A) or the same schedule of combined nivolumab and ipilimumab with the addition of SBRT to at least one tumour site (24 Gy in three fractions at week 2; group B). Patients had to have at least two measurable sites of disease so one non-irradiated site could be followed for response. The primary endpoint was objective response rate (ORR) in all randomly assigned patients who received at least one dose of combined nivolumab and ipilimumab. ORR was defined as the proportion of patients with a complete response or partial response per immune-related Response Evaluation Criteria in Solid Tumours. Response was assessed every 12 weeks. Safety was assessed in all patients. This trial is registered with ClinicalTrials.gov, NCT03071406.

FINDINGS

50 patients (25 in both group A and group B) were enrolled between March 14, 2017, and Dec 21, 2021, including 24 ICI-naive patients (13 [52%] of 25 group A patients and 11 [44%] of 25 group B patients]) and 26 patients with previous ICI (12 [48%] of 25 group A patients and 14 [56%] of 25 group B patients]). One patient in group B did not receive SBRT due to concerns about excess toxicity. Median follow-up was 14·6 months (IQR 9·1-26·5). Two patients in group B were excluded from the analysis of the primary endpoint because the target lesions were irradiated and so the patients were deemed non-evaluable. Of the ICI-naive patients, 22 (100%) of 22 (95% CI 82-100) had an objective response, including nine (41% [95% CI 21-63]) with complete response. Of the patients who had previously had ICI exposure, eight (31%) of 26 patients (95% CI 15-52) had an objective response and four (15% [5-36]) had a complete response. No significant differences in ORR were observed between groups A (18 [72%] of 25 patients) and B (12 [52%] of 23 patients; p=0·26). Grade 3 or 4 treatment-related adverse events were observed in 10 (40%) of 25 patients in group A and 8 (32%) of 25 patients in group B.

INTERPRETATION

First-line combined nivolumab and ipilimumab in patients with advanced Merkel cell carcinoma showed a high ORR with durable responses and an expected safety profile. Combined nivolumab and ipilimumab also showed clinical benefit in patients with previous anti-PD-1 and PD-L1 treatment. Addition of SBRT did not improve efficacy of combined nivolumab and ipilimumab. The combination of nivolumab and ipilimumab represents a new first-line and salvage therapeutic option for advanced Merkel cell carcinoma.

FUNDING

Bristol Myers Squibb Rare Population Malignancy Program.

Olfactory Receptor OR2H1 Is an Effective Target for CAR T Cells in Human Epithelial Tumors

Although chimeric antigen receptor (CAR)-expressing T cells have proven success in hematologic malignancies, their effectiveness in solid tumors has been largely unsuccessful thus far. We found that some olfactory receptors are expressed in a variety of solid tumors of different histologic subtypes, with a limited pattern of expression in normal tissues. Quantification of OR2H1 expression by qRT-PCR and Western blot analysis of 17 normal tissues, 82 ovarian cancers of various histologies, eight non-small cell lung cancers (NSCLCs), and 17 breast cancers demonstrated widespread OR2H1 expression in solid epithelial tumors with expression in normal human tissues limited to the testis. CAR T cells recognizing the extracellular domain of the olfactory receptor OR2H1 were generated with a targeting motif identified through the screening of a phage display library and demonstrated OR2H1-specific cytotoxic killing in vitro and in vivo, using tumor cells with spontaneous expression of variable OR2H1 levels. Importantly, recombinant OR2H1 IgG generated with the VH/VL sequences of the CAR construct specifically detected OR2H1 protein signal in 60 human lung cancers, 40 ovarian carcinomas, and 73 cholangiocarcinomas, at positivity rates comparable with mRNA expression and without OR2H1 staining in 58 normal tissues. CRISPR/Cas9-mediated ablation of OR2H1 confirmed targeting specificity of the CAR and the tumor-promoting role of OR2H1 in glucose metabolism. Therefore, T cells redirected against OR2H1-expressing tumor cells represent a promising therapy against a broad range of epithelial cancers, likely with an admissible toxicity profile.

Ovarian cancer immunogenicity is governed by a narrow subset of progenitor tissue-resident memory T cells

Despite repeated associations between T cell infiltration and outcome, human ovarian cancer remains poorly responsive to immunotherapy. We report that the hallmarks of tumor recognition in ovarian cancer-infiltrating T cells are primarily restricted to tissue-resident memory (TRM) cells. Single-cell RNA/TCR/ATAC sequencing of 83,454 CD3+CD8+CD103+CD69+ TRM cells and immunohistochemistry of 122 high-grade serous ovarian cancers shows that only progenitor (TCF1low) tissue-resident T cells (TRMstem cells), but not recirculating TCF1+ T cells, predict ovarian cancer outcome. TRMstem cells arise from transitional recirculating T cells, which depends on antigen affinity/persistence, resulting in oligoclonal, trogocytic, effector lymphocytes that eventually become exhausted. Therefore, ovarian cancer is indeed an immunogenic disease, but that depends on ∼13% of CD8+ tumor-infiltrating T cells (∼3% of CD8+ clonotypes), which are primed against high-affinity antigens and maintain waves of effector TRM-like cells. Our results define the signature of relevant tumor-reactive T cells in human ovarian cancer, which could be applicable to other tumors with unideal mutational burden.

CAR T cells targeting Olfactory Receptor OR2H1 are an effective immunotherapeutic option in human epithelial tumors

Chimeric antigen receptor (CAR) T cells have been successful for hematological malignancies, but so far showed limited efficiency against solid tumors. Olfactory receptors are expressed in a variety of epithelial cancers, with a limited expression in healthy tissues. We quantified olfactory receptor OR2H1 expression in ovarian cancer, non-small cell lung cancer (NSCLC), breast cancer, and many normal tissues, and we found OR2H1 is expressed in multiple solid epithelial tumors but limited to testis among healthy human tissues. CAR T cells targeting OR2H1-extracellular domain were generated, and OR2H1-specific cytotoxic killing was confirmed, both in vitro and in vivo. Correspondingly, OR2H1-CAR T cells mediate significant therapeutic effects against OR2H1+ NSCLC and high-grade serous ovarian cancer. Interestingly, OR2H1 ablation significantly delays malignant progression of at least NSCLC, but OR2H1 expression is found to be essential for the cytotoxic effects of the OR2H1-CAR T cells. In summary, T cells directed against OR2H1-expressing tumor cells could be a potential therapeutic approach in future for treating OR2H1-expressing cancers.

Supported by CA076292, R01CA157664, R01CA124515, R01CA178687, R01CA211913, U01CA232758 

Ovarian cancer immunogenicity is governed by a narrow subset of progenitor tissue-resident memory T-cells

Despite repeated associations between T-cell infiltration and patient outcome, human ovarian cancer remains poorly responsive to immunotherapy. We report that hallmarks of tumor recognition in ovarian cancer-infiltrating T-cells are primarily restricted to tissue-resident memory (TRM) cells. In mouse models we found that TRM T-cells were better than the re-circulating counterpart at controlling tumor growth. Single-cell RNA/TCR/ATAC sequencing of 83,454 CD3+CD8+CD103+CD69+ TRM cells and 24,175 CD3+CD8+CD103− re-circulating TILs showed that progenitor (TCF1low) tissue-resident memory T-cells (TRMstem cells) arise from transitional recirculating T-cells, which depends on antigen affinity/persistence, resulting in oligoclonal, trogocytic, effector lymphocytes. This effector population develops into proliferative lymphocytes that eventually become exhausted TRMs. Immunohistochemistry of 122 high-grade serous ovarian cancer tissues showed that only TRMstem cells, but not re-circulating TCF1+ T-cells, predict ovarian cancer outcome. Therefore, ovarian cancer is indeed an immunogenic disease that depends on ~13% of CD8+ tumor-infiltrating T-cells (~3% of CD8+ clonotypes), which are primed against high-affinity antigens and maintain waves of effector TRM cells.

Support for Shared Resources was provided by Cancer Center Support Grant (CCSG) CA076292 to H. Lee Moffitt Cancer Center and by CCSG CA010815 to The Wistar Institute. This study was supported by grants from NIH (R01CA157664, R01CA124515, R01CA178687, R01CA211913 and U01CA232758 to JRCG; R01CA184185 and RO1CA262121 to PCR.)

TGF-β-mediated silencing of genomic organizer SATB1 promotes Tfh cell differentiation and formation of intra-tumoral tertiary lymphoid structures

The immune checkpoint receptor PD-1 on T follicular helper (Tfh) cells promotes Tfh:B cell interactions and appropriate positioning within tissues. Here, we examined the impact of regulation of PD-1 expression by the genomic organizer SATB1 on Tfh cell differentiation. Vaccination of CD4^CreSatb1^f/f mice enriched for antigen-specific Tfh cells, and TGF-β-mediated repression of SATB1 enhanced Tfh differentiation of human T cells. Mechanistically, high Icos expression in Satb1^-/- CD4⁺ T cells promoted Tfh cell differentiation by preventing T follicular regulatory cell skewing and resulted in increased isotype-switched B cell responses in vivo. Ovarian tumors in CD4^CreSatb1^f/f mice accumulated tumor antigen-specific, LIGHT⁺CXCL13⁺IL-21⁺ Tfh cells and tertiary lymphoid structures (TLS). TLS formation decreased tumor growth in a CD4⁺ T cell and CXCL13-dependent manner. The transfer of Tfh cells, but not naive CD4⁺ T cells, induced TLS at tumor beds and decreased tumor growth. Thus, TGF-β-mediated silencing of Satb1 licenses Tfh cell differentiation, providing insight into the genesis of TLS within tumors.

Abstract 697: Defining anti-tumor immune stimulatory mechanisms of MEM-288, a CD40 ligand and IFN-beta dual-transgene armed oncolytic adenovirus

MEM-288 is a dual-transgene armed oncolytic adenovirus being developed for cancer treatment as a standalone agent or in combination with immune checkpoint inhibitors (ICI). MEM-288 is armed with two potent immune agonist transgenes: MEM40, a novel chimeric CD40 ligand (CD40L) designed for stable cell surface expression of CD40L that functions as a potent activator of CD40 expressing dendritic cells (DCs), and the DC and T cell activating cytokine IFNβ. We have evaluated MEM-288 activity in multiple in vivo immunocompetent mouse models to determine impact on systemic antitumor T cell activity after intratumoral virus injection. We were able to readily detect both tumor and immune cell infection and transgene expression following MEM-288 intratumoral administration in mouse tumor models and freshly resected human NSCLC tumors. MEM-288 injection in the syngeneic mouse lung metastatic model 344SQ demonstrated anti-metastatic activity that correlated with a significant enhancement in tumor infiltrating lymphocytes (TILs) and an increase in the systemic antitumor CD8 T cell response. MEM-288 also generated a highly efficacious response against both injected and distant non-injected contralateral tumors in the B16-F10 melanoma model, both as a monotherapy and in combination with ICI. These antitumor and immune responses were only found with MEM-288 as compared to the base adenovirus vector encoding only GFP transgene, indicating the observed effects were highly transgene-dependent. Dissecting the immune stimulatory effects further, we found MEM-288 injection in B16 tumors led to a significant increase in DC activation markers CD80 and CD86 suggesting that DCs may represent a key target of MEM-288 encoded transgenes leading to systemic T cell responses. In support of this hypothesis, we found the MEM-288 CD8 T cell response was completely abolished in BATF3 knockout (KO) mice which lack the cDC1 DC subset (CD8α conventional DC deficient). This suggests that cDC1s are a key mediator of MEM-288 activity. Furthermore, MEM-288 activity was also impaired in both CD40 and type 1 IFN receptor (IFNAR1) KO mice suggesting that both transgenes mediate MEM-288 immune stimulation. In summary, these results demonstrate MEM-288's capacity to induce a potent increase in systemic T cell responses through transgene-mediated stimulation of tumor DCs. This immune stimulatory capacity complements the additional mechanistic features of MEM-288, including enhanced tumor-specific viral replication, oncolysis, and tumor antigen release. MEM-288 is currently being prepared for first-in-human clinical testing in solid tumors as a monotherapy and in combination with ICI.

Citation Format: Hong Zheng, Chase D. Powell, Scott Antonia, Mark J. Cantwell, Bradford A. Perez, Amer A. Beg. Defining anti-tumor immune stimulatory mechanisms of MEM-288, a CD40 ligand and IFN-beta dual-transgene armed oncolytic adenovirus [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 697.

Impact of prior chemoradiotherapy-related variables on outcomes with durvalumab in unresectable Stage III NSCLC (PACIFIC)

INTRODUCTION

The PACIFIC trial demonstrated that durvalumab significantly improved progression-free and overall survival (PFS/OS), versus placebo, in patients with Stage III NSCLC and stable or responding disease following concurrent, platinum-based chemoradiotherapy (CRT). A range of CT and RT regimens were permitted, and used, in the trial. We report post-hoc, exploratory analyses of clinical outcomes from PACIFIC according to CRT-related variables.

METHODS

Patients were randomized 2:1 (1-42 days post-CRT) to up to 12 months durvalumab (10 mg/kg intravenously every 2 weeks) or placebo. Efficacy and safety were analyzed in patient subgroups defined by the following baseline variables: platinum-based CT (cisplatin/carboplatin); vinorelbine, etoposide, or taxane-based CT (all yes/no); total RT dose (<60 Gy/60-66 Gy/>66 Gy); time from last RT dose to randomization (<14 days/≥14 days); and use of pre-CRT induction CT (yes/no). Treatment effects for time-to-event endpoints were estimated by hazard ratios (HRs) from unstratified Cox-proportional-hazards models.

RESULTS

Overall, 713 patients were randomized, of whom 709 received treatment in either the durvalumab (n/N = 473/476) or placebo arms (n/N = 236/237). Durvalumab improved PFS, versus placebo, across all subgroups (median follow up, 14.5 months; HR range, 0.34-0.63). Durvalumab improved OS across most subgroups (median follow up, 25.2 months; HR range, 0.35-0.86); however, the 95 % confidence interval (CI) of the estimated treatment effect crossed one for the subgroups of patients who received induction CT (HR, 0.78 [95 % CI, 0.51-1.20]); carboplatin (0.86 [0.60-1.23]); vinorelbine (0.79 [0.49-1.27]); and taxane-based CT (0.73 [0.51-1.04]); and patients who were randomized ≥14 days post-RT (0.81 [0.62-1.06]). Safety was broadly similar across the CRT subgroups.

CONCLUSION

Durvalumab prolonged PFS and OS irrespective of treatment variables related to prior CRT to which patients with Stage III NSCLC had previously stabilized or responded. Limited patient numbers and imbalances in baseline factors in each subgroup preclude robust conclusions.

Outcomes with durvalumab by tumour PD-L1 expression in unresectable, stage III non-small-cell lung cancer in the PACIFIC trial

BACKGROUND

In the PACIFIC trial, durvalumab significantly improved progression-free and overall survival (PFS/OS) versus placebo, with manageable safety, in unresectable, stage III non-small-cell lung cancer (NSCLC) patients without progression after chemoradiotherapy (CRT). We report exploratory analyses of outcomes by tumour cell (TC) programmed death-ligand 1 (PD-L1) expression.

PATIENTS AND METHODS

Patients were randomly assigned (2:1) to intravenous durvalumab 10 mg/kg every 2 weeks or placebo ≤12 months, stratified by age, sex, and smoking history, but not PD-L1 status. Where available, pre-CRT samples were tested for PD-L1 expression (immunohistochemistry) and scored at pre-specified (25%) and post hoc (1%) TC cut-offs. Treatment-effect hazard ratios (HRs) were estimated from unstratified Cox proportional hazards models (Kaplan-Meier-estimated medians).

RESULTS

In total, 713 patients were randomly assigned, 709 of whom received at least 1 dose of study treatment durvalumab (n = 473) or placebo (n = 236). Some 451 (63%) were PD-L1-assessable: 35%, 65%, 67%, 33%, and 32% had TC ≥25%, <25%, ≥1%, <1%, and 1%-24%, respectively. As of 31 January 2019, median follow-up was 33.3 months. Durvalumab improved PFS versus placebo (primary-analysis data cut-off, 13 February 2017) across all subgroups [HR, 95% confidence interval (CI); medians]: TC ≥25% (0.41, 0.26-0.65; 17.8 versus 3.7 months), <25% (0.59, 0.43-0.82; 16.9 versus 6.9 months), ≥1% (0.46, 0.33-0.64; 17.8 versus 5.6 months), <1% (0.73, 0.48-1.11; 10.7 versus 5.6 months), 1%-24% [0.49, 0.30-0.80; not reached (NR) versus 9.0 months], and unknown (0.59, 0.42-0.83; 14.0 versus 6.4 months). Durvalumab improved OS across most subgroups (31 January 2019 data cut-off; HR, 95% CI; medians): TC ≥ 25% (0.50, 0.30-0.83; NR versus 21.1 months), <25% (0.89, 0.63-1.25; 39.7 versus 37.4 months), ≥1% (0.59, 0.41-0.83; NR versus 29.6 months), 1%-24% (0.67, 0.41-1.10; 43.3 versus 30.5 months), and unknown (0.60, 0.43-0.84; 44.2 versus 23.5 months), but not <1% (1.14, 0.71-1.84; 33.1 versus 45.6 months). Safety was similar across subgroups.

CONCLUSIONS

PFS benefit with durvalumab was observed across all subgroups, and OS benefit across all but TC <1%, for which limitations and wide HR CI preclude robust conclusions.

Analysis of Relapse Events After Definitive Chemoradiotherapy in Locally Advanced Non-Small-Cell Lung Cancer Patients

BACKGROUND

The appropriate follow-up frequency after definitive chemoradiotherapy (CRT) for locally advanced non-small-cell lung cancer patients is unknown. Although surveillance guidelines have been proposed, very few data support current recommendations. Here we analyze relapse events after CRT and investigate whether symptomatic relapses versus those detected by surveillance imaging influences outcomes.

PATIENTS AND METHODS

Stage III non-small-cell lung cancer patients treated with CRT at our institution between 2005 and 2014 were retrospectively analyzed. Relapse events were grouped into posttreatment intervals and analyzed with cumulative tables. Time to relapse and overall survival (OS) were compared between patients with relapse detection via symptomatic presentation versus surveillance imaging.

RESULTS

A total of 211 patients were identified for analysis. The median follow-up was 43 months for patients alive at the time of analysis. The median age was 63 years, and equal proportions had IIIA or IIIB disease. A total of 135 patients (64%) experienced disease relapse, and of these, 74% did so within 12 months. In those who did not experience relapse at ≤ 12 months, 16%, 6%, and < 5% experienced relapse during 12 to 24, 24 to 36, and > 36 months of follow-up, respectively. In patients with relapse, 56% presented symptomatically, which led to inferior median OS compared to those identified by surveillance imaging (23 vs. 36 months; P = .013).

CONCLUSION

This study identified that most relapses occur within 1 year of completing CRT, and approximately half of these occur within 6 months. A symptomatic relapse led to inferior OS. More aggressive surveillance imaging may therefore identify asymptomatic relapses that are amenable to earlier salvage therapy.

Extracranial metastatic burden in extensive-stage small cell lung cancer: implications for prophylactic cranial irradiation

Background

Patients with extensive-stage small cell lung cancer (ES-SCLC) often develop brain metastases. There is significant controversy regarding the benefit of prophylactic cranial irradiation (PCI) for patients with ES-SCLC. Our objective is to identify ES-SCLC patients who might be most likely to benefit from PCI.

Methods

We retrospectively reviewed 173 patients with ES-SCLC treated between 2010-2015. Of these, 117 patients were initially diagnosed without brain metastases and received systemic chemotherapy. Following exclusion of patients who received PCI and less than 2 cycles of platinum doublet therapy, 93 patients remained. Patient records were reviewed for clinical and radiographic features previously identified as relevant risk factors. Primary outcome was brain metastasis-free survival (BMFS). Kaplan-Meier analysis, log-rank tests and Cox multivariate models were used to compare outcomes.

Results

Median follow-up was 10.7 months (range, 3-58 months). Thirty-eight (40.9%) patients developed brain metastases. Three or more metastatic sites was associated with inferior BMFS on univariable (1-year estimate 43.8% vs. 61.3%; P=0.020) and multivariable (MVA) analysis [hazard ratio (HR) 2.33, 95% CI: 1.08-5.01; P=0.03).

Conclusions

Our results suggest that extracranial metastatic burden is associated with an increased risk for brain metastases in patients with ES-SCLC. As there is no clear standard regarding delivery of PCI in this patient population, utilizing the number of metastatic disease sites as a clinical indicator may help to improve selection of patients who benefit from PCI.

Radiosensitivity of Lung Metastases by Primary Histology and Implications for Stereotactic Body Radiation Therapy Using the Genomically Adjusted Radiation Dose

INTRODUCTION

We assessed the radiosensitivity of lung metastases on the basis of primary histologic type by using a validated gene signature and model lung metastases for the gnomically adjusted radiation dose (GARD).

METHODS

Tissue samples were identified from our prospective observational protocol. The radiosensitivity index (RSI) 10-gene assay was run on samples and calculated alongside the GARD by using the previously published algorithms. A cohort of 105 patients with 137 lung metastases treated with stereotactic body radiation therapy (SBRT) at our institution was used for clinical correlation.

RESULTS

A total of 138 unique metastatic lung lesions from our institution's tissue biorepository were identified for inclusion. There were significant differences in the RSI of lung metastases on the basis of histology. In order of decreasing radioresistance, the median RSIs for the various histologic types of cancer were endometrial adenocarcinoma (0.49), soft-tissue sarcoma (0.47), melanoma (0.44), rectal adenocarcinoma (0.43), renal cell carcinoma (0.33), head and neck squamous cell cancer (0.33), colon adenocarcinoma (0.32), and breast adenocarcinoma (0.29) (p = 0.002). We modeled the GARD for these samples and identified the biologically effective dose necessary to optimize local control. The 12- and 24-month Kaplan-Meier rates of local control for radioresistant versus radiosensitive histologic types from our clinical correlation cohort after lung SBRT were 92%/87% and 100%, respectively (p = 0.02).

CONCLUSIONS

In this analysis, we have noted significant differences in radiosensitivity on the basis of primary histologic type of lung metastases and have modeled the biologically effective dose necessary to optimize local control. This study suggests that primary histologic type may be an additional factor to consider in selection of SBRT dose to the lung and that dose personalization may be feasible.

Richieri-Costa-Pereira syndrome: Expanding its phenotypic and genotypic spectrum

Richieri-Costa-Pereira syndrome is a rare autosomal recessive acrofacial dysostosis that has been mainly described in Brazilian individuals. The cardinal features include Robin sequence, cleft mandible, laryngeal anomalies and limb defects. A biallelic expansion of a complex repeated motif in the 5' untranslated region of EIF4A3 has been shown to cause this syndrome, commonly with 15 or 16 repeats. The only patient with mild clinical findings harbored a 14-repeat expansion in 1 allele and a point mutation in the other allele. This proband is described here in more details, as well as is his affected sister, and 5 new individuals with Richieri-Costa-Pereira syndrome, including a patient from England, of African ancestry. This study has expanded the phenotype in this syndrome by the observation of microcephaly, better characterization of skeletal abnormalities, less severe phenotype with only mild facial dysmorphisms and limb anomalies, as well as the absence of cleft mandible, which is a hallmark of the syndrome. Although the most frequent mutation in this study was the recurrent 16-repeat expansion in EIF4A3, there was an overrepresentation of the 14-repeat expansion, with mild phenotypic expression, thus suggesting that the number of these motifs could play a role in phenotypic delineation.

Efficacy and Safety of Low-Dose Iodine Plaque Brachytherapy for Juxtapapillary Choroidal Melanoma

PURPOSE

To evaluate low- vs high-dose plaque brachytherapy for juxtapapillary choroidal melanoma.

DESIGN

Retrospective interventional case series.

METHODS

Setting: Single institution.

STUDY POPULATION

Forty-seven patients with juxtapapillary choroidal melanoma.

INTERVENTION

Iodine-125 plaque brachytherapy. Eyes were divided into apex low-dose (LD) and high-dose (HD) groups (≤ or > median apex dose 84.35 Gy). Main outcome measures were time to distant failure, local failure, death, enucleation, radiation retinopathy, optic neuropathy, and best-corrected visual acuity (BCVA).

RESULTS

Freedom from distant failure rates were 96% and 95% in apex LD and HD groups at 5 years and 77% and 95% at 10 years, respectively (P = .84). Freedom from local failure rates were 90% in the apex LD group vs 89% in the HD group at 5 and 10 years (P = .96). Apex LD and HD groups did not differ for time to death or enucleation. Five- and 10-year freedom from radiation retinopathy and optic neuropathy rates were higher in the apex LD than HD group. Loss of ≥3 BCVA lines, final BCVA 20/40 or better, and final BCVA 20/200 or worse were more favorable in the 5 mm LD compared to HD group. Visual acuity outcomes did not differ between apex LD and HD groups.

CONCLUSIONS

Low-dose iodine-125 plaque brachytherapy (67.5-81 Gy at tumor apex) provides safe and effective tumor control for juxtapapillary choroidal melanoma and may be associated with reduced radiation toxicity. Larger trials are needed to determine the optimal therapeutic dose for juxtapapillary choroidal melanoma.

Quantitatively Excessive Normal Tissue Toxicity and Poor Target Coverage in Postoperative Lung Cancer Radiotherapy Meta-analysis

BACKGROUND

A previous meta-analysis (MA) found postoperative radiotherapy (PORT) in lung cancer patients to be detrimental in N0/N1 patients and equivocal in the N2 setting. We hypothesized that treatment plans generated using MA protocols had worse dosimetric outcomes compared to modern plans.

PATIENTS AND METHODS

We retrieved plans for 13 patients who received PORT with modern planning. A plan was recreated for each patient using the 8 protocols included in MA. Dosimetric values were then compared between the modern and simulated MA plans.

RESULTS

A total of 104 MA plans were generated. Median prescribed dose was 50.4 (range, 50-60) Gy in the modern plans and 53.2 (30-60) Gy in the MA protocols. Median planning volume coverage was 96% (93%-100%) in the modern plans, versus 58% (0%-100%) in the MA plans (P < .001). Internal target volume coverage was 100% (99%-100%) versus 65% (0%-100%), respectively (P < .001). Organs at risk received the following doses: spinal cord maximum dose, 36.8 (4.6-50.4) Gy versus 46.8 (2.9-74.0) Gy (P < .001); esophageal mean dose, 22.9 (5.5-35) Gy versus 30.5 (11.1-52.5) Gy (P = .003); heart V30 (percentage of volume of an organ receiving at least a dose of 30 Gy), 16% (0%-45%) versus 35% (0%-79%) (P = .047); mean lung dose, 12.4 (3.4-24.3) Gy versus 14.8 (4.1-27.4) Gy (P = .008); and lung V20, 18% (4%-34%) versus 25% (8%-67%) (P = .023).

CONCLUSION

We quantitatively confirm the inferiority of the techniques used in the PORT MA. Our analysis showed a lower therapeutic ratio in the MA plans, which may explain the poor outcomes in the MA. The findings of the MA are not relevant in the era of modern treatment planning.

Tumor cells, but not endothelial cells, mediate eradication of primary sarcomas by stereotactic body radiation therapy

Cancer clinics currently use high-dose stereotactic body radiation therapy as a curative treatment for several kinds of cancers. However, the contribution of vascular endothelial cells to tumor response to radiation remains controversial. Using dual recombinase technology, we generated primary sarcomas in mice with targeted genetic mutations specifically in tumor cells or endothelial cells. We selectively mutated the proapoptotic gene Bax or the DNA damage response gene Atm to genetically manipulate the radiosensitivity of endothelial cells in primary soft tissue sarcomas. Bax deletion from endothelial cells did not affect radiation-induced cell death in tumor endothelial cells or sarcoma response to radiation therapy. Although Atm deletion increased endothelial cell death after radiation therapy, deletion of Atm from endothelial cells failed to enhance sarcoma eradication. In contrast, deletion of Atm from tumor cells increased sarcoma eradication by radiation therapy. These results demonstrate that tumor cells, rather than endothelial cells, are critical targets that regulate sarcoma eradication by radiation therapy. Treatment with BEZ235, a small-molecule protein kinase inhibitor, radiosensitized primary sarcomas more than the heart. These results suggest that inhibiting ATM kinase during radiation therapy is a viable strategy for radiosensitization of some tumors.

Propelling Immunotherapy Combinations Into the Clinic

Immune checkpoint inhibitors produce durable long-term survival in some patients with advanced melanoma and lung cancer. Better immune targets and combination strategies can harness the immune system by supporting the three elements of a successful T-cell antitumor response: (A) generation of sufficient numbers of antitumor T cells within the lymphoid compartment; (B) effective T-cell trafficking and extravasation out of the lymphoid compartment, through the bloodstream, and into the tumor microenvironment; and (C) T-cell effector function within the tumor microenvironment that is characterized by the ability to bypass immune checkpoints, soluble and metabolic inhibitory factors, and inhibitory cells. Strategies that hold promise include dual immune checkpoint blockade, as well as the combination of immune checkpoint blockade with costimulatory receptor agonists, enhancers of innate immunity, inhibition of indoleamine 2,3-dioxygenase, adoptive T-cell transfer/T-cell engineering, therapeutic vaccines, small-molecule inhibitors, and radiation therapy. Novel, rational clinical trial designs seek to combine targeted agents and one or more immune checkpoint inhibitors, with the goal of producing deep and durable antitumor responses, which thus far have been observed in only a minority of patients.

Uveal melanoma treated with iodine-125 episcleral plaque: an analysis of dose on disease control and visual outcomes

PURPOSE

To investigate, in the treatment of uveal melanomas, how tumor control, radiation toxicity, and visual outcomes are affected by the radiation dose at the tumor apex.

METHODS AND MATERIALS

A retrospective review was performed to evaluate patients treated for uveal melanoma with (125)I plaques between 1988 and 2010. Radiation dose is reported as dose to tumor apex and dose to 5 mm. Primary endpoints included time to local failure, distant failure, and death. Secondary endpoints included eye preservation, visual acuity, and radiation-related complications. Univariate and multivariate analyses were performed to determine associations between radiation dose and the endpoint variables.

RESULTS

One hundred ninety patients with sufficient data to evaluate the endpoints were included. The 5-year local control rate was 91%. The 5-year distant metastases rate was 10%. The 5-year overall survival rate was 84%. There were no differences in outcome (local control, distant metastases, overall survival) when dose was stratified by apex dose quartile (<69 Gy, 69-81 Gy, 81-89 Gy, >89 Gy). However, increasing apex dose and dose to 5-mm depth were correlated with greater visual acuity loss (P=.02, P=.0006), worse final visual acuity (P=.02, P<.0001), and radiation complications (P<.0001, P=.0009). In addition, enucleation rates were worse with increasing quartiles of dose to 5 mm (P=.0001).

CONCLUSIONS

Doses at least as low as 69 Gy prescribed to the tumor apex achieve rates of local control, distant metastasis-free survival, and overall survival that are similar to radiation doses of 85 Gy to the tumor apex, but with improved visual outcomes.

Stereotactic body radiotherapy: a critical review for nonradiation oncologists

Stereotactic body radiotherapy (SBRT) involves the treatment of extracranial primary tumors or metastases with a few, high doses of ionizing radiation. In SBRT, tumor kill is maximized and dose to surrounding tissue is minimized, by precise and accurate delivery of multiple radiation beams to the target. This is particularly challenging, because extracranial lesions often move with respiration and are irregular in shape, requiring careful treatment planning and continual management of this motion and patient position during irradiation. This review presents the rationale, process workflow, and technology for the safe and effective administration of SBRT, as well as the indications, outcome, and limitations for this technique in the treatment of lung cancer, liver cancer, and metastatic disease.

Assessing the radiation response of lung cancer with different gene mutations using genetically engineered mice

Purpose: Non-small cell lung cancers (NSCLC) are a heterogeneous group of carcinomas harboring a variety of different gene mutations. We have utilized two distinct genetically engineered mouse models of human NSCLC (adenocarcinoma) to investigate how genetic factors within tumor parenchymal cells influence the in vivo tumor growth delay after one or two fractions of radiation therapy (RT).

Materials and Methods: Primary lung adenocarcinomas were generated in vivo in mice by intranasal delivery of an adenovirus expressing Cre-recombinase. Lung cancers expressed oncogenic Kras^G12D and were also deficient in one of two tumor suppressor genes: p53 or Ink4a/ARF. Mice received no radiation treatment or whole lung irradiation in a single fraction (11.6 Gy) or in two 7.3 Gy fractions (14.6 Gy total) separated by 24 h. In each case, the biologically effective dose (BED) equaled 25 Gy₁₀. Response to RT was assessed by micro-CT 2 weeks after treatment. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemical staining were performed to assess the integrity of the p53 pathway, the G1 cell-cycle checkpoint, and apoptosis.

Results: Tumor growth rates prior to RT were similar for the two genetic variants of lung adenocarcinoma. Lung cancers with wild-type (WT) p53 (LSL-Kras; Ink4a/ARF^FL/FL mice) responded better to two daily fractions of 7.3 Gy compared to a single fraction of 11.6 Gy (P = 0.002). There was no statistically significant difference in the response of lung cancers deficient in p53 (LSL-Kras; p53^FL/FL mice) to a single fraction (11.6 Gy) compared to 7.3 Gy × 2 (P = 0.23). Expression of the p53 target genes p21 and PUMA were higher and bromodeoxyuridine uptake was lower after RT in tumors with WT p53.

Conclusion: Using an in vivo model of malignant lung cancer in mice, we demonstrate that the response of primary lung cancers to one or two fractions of RT can be influenced by specific gene mutations.

Glomerella Leaf Spot Caused by a Nonhomothallic Strain of Glomerella cingulata on Highbush Blueberry Nursery Plants in Buenos Aires, Argentina

In February 2009, irregular-shaped leaf spots affected blueberry (Vaccinium corymbosum L. 'Blue Crisp', 'Misty', and 'Sharp Blue') nursery plants in Buenos Aires. Single-spore cultures on potato dextrose agar and oat agar showed aerial white mycelium that turned light and dark gray, dark brown acervuli with setae, and a salmon-to-orange conidial mass. Septate, dark brown, 62 to 78 μm long setae were abundant in the acervulus. Conidia were unicellular, hyaline, straight, cylindrical, round at the ends, and averaged 15.2 (12.1 to 16.9) × 5.4 (4.9 to 6.2) μm. Dark brown, ovate to clavate, 10.25 × 6.25 μm (9 to 12 × 5 to 8) appressoria with a noticeable pore formed on slides near the edge of the cover glass. Dark subglobose structures were recorded immersed in the culture medium. No asci or ascospores were observed, indicating a nonhomothallic condition. The fungus was identified as Colletotrichum gloeosporioides (Penz.) Penz & Sacc. (teleomorph Glomerella cingulata (Stoneman) Spauld. & H. Schrenk) with traits similar to those already described (1). DNA was obtained from mycelium with a standard DNA extraction kit and the ribosomal, internal transcribed spacer (ITS) 1 and ITS2 regions were PCR amplified and sequenced with primers ITS1 and ITS4 (2). A BLASTN algorithm search revealed 100% identity of the sequence (535 bp long) with G. cingulata/C. gloeosporioides from citrus and mango and one from coffee identified as C. kahawae (GenBank Accession No. JF908919). The nucleotide sequence was deposited in GenBank (Accession No. JQ340087). Pathogenicity was verified on young plants and detached leaves of highbush blueberry 'Emerald', 'Misty', 'O'Neal', and 'Santa Fe', olive (Olea europaea 'Arbequina'), and marketed fruits of apple, mango, orange, and tomato. Disinfected healthy leaves were inoculated with a 9-mm² mycelial block and incubated at 24°C with 12 h of light. Young plants were infected by placing the disinfected end of the branches within a micropipette tip filled with mycelium and kept under greenhouse conditions. Asymptomatic fruits of apple, mango, orange, and tomato were inoculated by placing a mycelial block on a small wound made on their surface. Detached leaves of highbush blueberry 'Emerald', 'O'Neal', 'Misty', and 'Santa Fe' showed 0.1 to 1.5 × 0.8 to 2 cm necrotic lesions after 3 days, covering 43 to 100% of the 'Emerald' leaf area after 8 days. Young plants of blueberry 'Emerald' and 'Misty' showed 1.5 to 3 cm necrotic lesions, acervuli, a salmon-orange conidial mass, and death of leaves at 25 days. On olive 'Arbequina', leaf necrotic lesions reached 0.1 to 3.5 cm after 5 days. Symptoms developed slowly on infected tomato fruits while inoculated fruits of apple, mango, and orange showed dark brown lesions that measured 2 to 7 × 1 to 3.5 cm at 5 days. No symptoms were observed on controls. The fungus was reisolated from inoculated plant parts. The disease was previously cited in Argentina (3), but to our knowledge, this is the first report of a nonhomothallic strain of G. cingulata from highbush blueberry colonizing and deteriorating fruits of apple, mango, orange, and tomato. References: (1) J. M. E. Mourde. No 315. CMI Descriptions of Pathogenic Fungi and Bacteria. Kew, Surrey, UK, 1971. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (3) E.R. Wright et al. OEPP/EPPO Bull. 28:219, 1998.

First Report of Fusarium solani Causing Root Rot of Olive in Southeastern Argentina

In Argentina, olive (Olea europaea L.) is cultivated in the mountainous, warm, arid northwest (Andes range), where Fusarium solani (blue sporodochia) is frequently found to be causing death of nursery and young field plants (1). Recently, olive orchards were established more than 1,600 km to the southeast (Pampas) in a plain with a temperate and humid climate and in the arid Patagonia, both influenced by the Atlantic Ocean. This area includes part of Buenos Aires and Rio Negro provinces. In March 2008, 10-year-old 'Barnea' olive trees with high incidence of root rot, dried leaves, dead branches, and dead plants were observed in the Coronel Dorrego District of Buenos Aires Province, where oat, barley or other cereals are planted between rows of olive trees. Planting material originated from olive nurseries located in Mendoza Province, 1,200 km from Coronel Dorrego. Diseased roots were disinfected in 2% NaOCl and 70% ethanol, cut into small pieces, plated onto rose bengal-glycerin-urea medium, and incubated at 20°C with a 12-h photopheriod. A fungus was purified through successive transfers of hyphal tips from the margin of a sparsely growing colony onto 2% water agar (2). Colonies grown on Spezieller Nährstoffarmer agar (3) and carnation leaf-piece agar were used for morphological identification, and those on grown on potato dextrose agar were used for evaluation of pigmentation and colony growth rate. Sporodochium color, cream, was typical of F. solani (Mart.) Sacc. This isolate was deposited in the IMYZA Microbial Collection as INTA-IMC 73. Mycelium was cultured in liquid Czapek-Dox medium supplemented with sucrose, peptone, yeast extract, sodium nitrate, and vitamins for 4 days and fungal DNA was obtained with a DNA extraction kit. Primers ITS1 and ITS4 were used to amplify the internal transcribed spacer (ITS) region of ribosomal genes. The purified PCR product was sequenced and the DNA sequence compared with GenBank records. The sequence shared 100% identity with 27 entries for F. solani and 97% identity with F. solani obtained from olive in Nepal (4), corresponding to EU912432 and EU912433. The nucleotide sequence was registered in GenBank as JF299258. Pathogenicity was confirmed on 'Manzanilla' plants at the eight-leaf stage. Pieces of water agar with mycelium were applied to small wounds at the stem base and on roots of 10 plants and were covered with cotton soaked in sterile distilled water. Plants were incubated at 20°C and a 14-h photoperiod. On control plants, water agar pieces without mycelium were applied to the wounds. After 33 days, inoculated plants showed dark brown lesions (average length 1.4 cm) and leaf chlorosis. Two plants showed wilting with leaves remaining attached to branches. F. solani was reisolated from roots and stem bases of inoculated plants. Controls remained asymptomatic. To our knowledge, this is the first report of F. solani occurring on olive in the temperate part of the Pampas of Argentina where cereals, which are susceptible to Fusarium species, are grown with olive trees. Sporodochium color (cream) of these isolates differed from the blue color of previously reported isolates of F. solani on olive in northwestern Argentina (1). References: (1) S. Babbitt et al. Plant Dis. 86:326, 2002. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (3) H. I. Nirenberg. Releases Fed. Biol. Res. Center Agric. For. (Berlin-Dahlem) 169:1, 1976. (4) A. M. Vettraino et al. Plant Dis. 23:200, 2009.

First Report of Sclerotinia Rot on Blueberry Caused by Sclerotinia sclerotiorum in Argentina

In October 2007, blighted shoots were observed on highbush blueberry (Vaccinium corymbosum L. cv. O'Neal) plants in La Plata, Buenos Aires Province, Argentina. Isolations from surface-disinfested shoots onto carrot agar and Spezieller Nahrstoffarmer Agar (SNA) consistently yielded white colonies that produced black sclerotia, mainly near the edge of the culture plates, after 7 days. Sclerotia were transferred to SNA tubes and kept at 5°C for several months. The germination of sclerotia produced numerous 6 mm long initials, stipitate pale brown cup-shaped apothecia (10 × 6 mm) with eight-spored asci (137 × 7 μm) at 18°C and continuous light conditions. Asci with uniseriate ascospores were cylindrical and narrow at the base. Ascospores (11 to 12 × 4 μm) were hyaline, unicellular, smooth, and ellipsoid. This isolated fungus was morphologically identified as Sclerotinia sclerotiorum (Lib.) de Bary (2,3). The isolate was deposited in the IMYZA Microbial Collection as INTA-IMC 87. Mycelium was cultured in 100 ml of Czapek's-Dox medium, supplemented with sucrose, peptone, yeast extract, sodium nitrate, and vitamins (1), for 3 days and fungal DNA was obtained using a DNA extraction kit. ITS1 and ITS2 of ribosomal genes were amplified by PCR using universal primers (4) and the PCR product was sequenced. A BLAST algorithm search revealed 100% identity of the sequence with 12 GenBank entries for S. sclerotiorum. The nucleotide sequence was deposited in the GenBank with Accession No. JF277567. Pathogenicity testing was achieved by placing detached leaves of cvs. Emerald, Misty, and Start on water agar (WA) plates, inoculating with 9-mm² mycelial blocks, and incubating at 20°C with 12 h of light. Young shoots of highbush blueberry, Misty and O'Neal, were inoculated by the cut shoot method with micropipette tips filled with mycelium and kept under greenhouse conditions at 24°C and 14 h of light. On control plants, WA blocks or WA-filled micropipette tips were used. Leaf blight was observed after 5 to 6 days and sclerotia appeared after 7 days on inoculated tissues. Shoot blight was recorded on inoculated plants after 5 days. The fungus was reisolated from inoculated tissues, with no symptoms showing on controls. To our knowledge, this is the first report of Sclerotinia rot caused by S. sclerotiorum in blueberry in Argentina. References: (1) J.F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Hoboken, NJ, 2006. (2). J. E. M. Mourde and P. Holliday. No. 513 in: CMI Descriptions of Pathogenic Fungi and Bacteria. Kew, Surrey, UK, 1976. (3) S. Umemoto et al. Gen. Plant Pathol. 73:290, 2007. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

Imaging primary lung cancers in mice to study radiation biology

PURPOSE

To image a genetically engineered mouse model of non-small-cell lung cancer with micro-computed tomography (micro-CT) to measure tumor response to radiation therapy.

METHODS AND MATERIALS

The Cre-loxP system was used to generate primary lung cancers in mice with mutation in K-ras alone or in combination with p53 mutation. Mice were serially imaged by micro-CT, and tumor volumes were determined. A comparison of tumor volume by micro-CT and tumor histology was performed. Tumor response to radiation therapy (15.5 Gy) was assessed with micro-CT.

RESULTS

The tumor volume measured with free-breathing micro-CT scans was greater than the volume calculated by histology. Nevertheless, this imaging approach demonstrated that lung cancers with mutant p53 grew more rapidly than lung tumors with wild-type p53 and also showed that radiation therapy increased the doubling time of p53 mutant lung cancers fivefold.

CONCLUSIONS

Micro-CT is an effective tool to noninvasively measure the growth of primary lung cancers in genetically engineered mice and assess tumor response to radiation therapy. This imaging approach will be useful to study the radiation biology of lung cancer.

Phase-selective image reconstruction of the lungs in small animals using Micro-CT

Gating in small animal imaging can compensate for artifacts due to physiological motion. This paper presents a strategy for sampling and image reconstruction in the rodent lung using micro-CT. The approach involves rapid sampling of free-breathing mice without any additional hardware to detect respiratory motion. The projection images are analyzed post-acquisition to derive a respiratory signal, which is used to provide weighting factors for each projection that favor a selected phase of the respiration (e.g. end-inspiration or end-expiration) for the reconstruction. Since the sampling cycle and the respiratory cycle are uncorrelated, the sets of projections corresponding to any of the selected respiratory phases do not have a regular angular distribution. This drastically affects the image quality of reconstructions based on simple filtered backprojection. To address this problem, we use an iterative reconstruction algorithm that combines the Simultaneous Algebraic Reconstruction Technique with Total Variation minimization (SART-TV). At each SART-TV iteration, backprojection is performed with a set of weighting factors that favor the desired respiratory phase. To reduce reconstruction time, the algorithm is implemented on a graphics processing unit. The performance of the proposed approach was investigated in simulations and in vivo scans of mice with primary lung cancers imaged with our in-house developed dual tube/detector micro-CT system. We note that if the ECG signal is acquired during sampling, the same approach could be used for phase-selective cardiac imaging.

Small numbers of residual tumor cells at the site of primary inoculation are critical for anti-tumor immunity following challenge at a secondary location

Luciferase-transduced B16 murine melanoma cells (luc-B16) inoculated in ear skin do not form tumors but prevent tumor formation by luc-B16 cells injected into the footpad. To determine the requirements for such immunity, we followed the fate of luc-B16 cells following ear injection. Surprisingly, small numbers of viable luc-B16 cells were detected in tumor-free mouse skin for up to 60 days post-inoculation. After 1 week, the number of Foxp3(+)CD4(+)CD25(+) T cells (along with foxp3 mRNA expression) increased rapidly in the injected ear skin. Residual tumor cells in ears were reduced in mice treated with anti-CD25 mAb and in CD4-deficient mice, but increased in CD8-deficient mice. Strikingly, the loss of luc-B16 cells in the ear skin, either spontaneously or following amputation of the injected ear, resulted in significantly enhanced tumor formation by parental and luciferase-expressing B16 cells after footpad injection. These studies suggest that small numbers of tumor cells (possibly regulated by CD4(+)CD25(+) regulatory T cells expressing Foxp3) are required for effective host anti-tumor responses at alternate inoculation sites.

Genetic analysis of the requirement for flp-2, tadV, and rcpB in Actinobacillus actinomycetemcomitans biofilm formation

The tad locus of Actinobacillus actinomycetemcomitans encodes a molecular transport system required for tenacious, nonspecific adherence to surfaces and formation of extremely strong biofilms. This locus is dedicated to the biogenesis of Flp pili, which are required for colonization and virulence. We have previously shown that 11 of the 14 tad locus genes are required for adherence and Flp pilus production. Here, we present genetic and phylogenetic analyses of flp-2, tadV, and rcpB genes in biofilm formation. We show that tadV, predicted to encode prepilin peptidase, is required for adherence. In contrast, targeted insertional inactivation of flp-2, a gene closely related to the prepillin gene flp-1, did not abrogate biofilm formation. Expression studies did not detect Flp2-T7 protein under standard laboratory conditions. We present phylogenetic data showing that there is no significant evidence for natural selection in the available flp-2 sequences from A. actinomycetemcomitans, suggesting that flp-2 does not play a significant role in the biology of this organism. Mutants with insertions at the 3' end of rcpB formed biofilms equivalent to wild-type A. actinomycetemcomitans. Surprisingly, 5' end chromosomal insertion mutants in rcpB were obtained only when a wild-type copy of the rcpB gene was provided in trans or when the Tad secretion system was inactivated. Together, our results strongly suggest that A. actinomycetemcomitans rcpB is essential in the context of a functional tad locus. These data show three different phenotypes for the three genes.

Access as a managed care marketing outcomes measure

As their position in the health care market diminishes, HMOs are feeling the pinch from the competition. Purchasers of health plans have many more options available today than in the past. Employers can select from single or consolidated health plans, plans offered by coalitions, or plans offered by provider systems. Following closely behind the withstanding issue of controlling costs is quality of care and customer satisfaction. The bad press surrounding managed care is making employers demand assurances that employees will receive the best quality of care their money can buy. To assist in this endeavor managed care companies are focusing more on their customers. To this end marketers use report cards to assess purchaser and enrollee satisfactions, with the hope that if they have a happy customer, s/he will be a loyal one. This paper reviews current marketing strategies of managed care companies and their level of usefulness with respect to sustaining customers and hence market share.

Congenital perilymphatic fistula and associated middle ear abnormalities

To specifically determine the frequency and type of middle ear abnormalities associated with perilymphatic fistula (PLF), a retrospective chart review was performed of 94 patients (117 ears) who underwent exploratory tympanotomy for PLF from 1980 to 1989. Of the 117 ears explored, 80 (68.4%) had a PLF, and in 65 (81.3%) of these ears, a middle ear malformation was associated with the PLF. Of these 65 ears in which a congenital middle ear abnormality was observed, a malformed stapes was the most common abnormality seen (39 ears, 60%), followed by a deformed round window (20 ears, 30.8%), a deformed incus (11 ears, 16.9%), and a deformed promontory (2 ears, 3%). Often these malformations coexisted amongst themselves or with inner ear abnormalities. Sixteen children (25 ears) had an inner ear malformation identified on computed tomography (CT); all of these children had a PLF found at the time of surgery. This study demonstrated that 86.3% of the ears found to have a PLF had a deformity of the middle ear, inner ear, or both. A malformation of the stapes, most frequently identified as a deformity of its superstructure (and presumably also the anterior footplate), was the most common congenital middle ear abnormality found to be associated with PLF in children.