Real-World Toxicity of Conventional Versus Hypofractionated Definitive Prostate Radiotherapy across a Large, Diverse, Academic and Community-Based Enterprise

PURPOSE/OBJECTIVE(S)

Over the past 10-15 years there has been increasing adoption of moderate hypofractionation (HF) for definitive prostate radiotherapy as compared to conventional fractionation (CF). Based on several randomized trials hypofractionation results in equivalent treatment efficacy with similar rates of long-term toxicity. However, some studies suggest higher acute GI toxicity with moderate hypofractionation. We sought to compare the rates of toxicity between these two groups across our enterprise including 16 community-based practices and one academic NCI-designated comprehensive cancer center.

MATERIALS/METHODS

We retrospectively extracted radiation treatment intent from our network-wide clinical pathways for patients diagnosed with prostate cancer between 3/2019 and 10/2022. Patients treated after prostatectomy and those treated with brachytherapy or SBRT were excluded. For the remaining 1529 patients treated with either conventional fractionation or moderate hypofractionation, we identified and merged physician-graded toxicity data using CTCAE version 5.0 recorded in their electronic medical record at each weekly on-treatment visit and follow-up. A total of 1051 patients had toxicity data available. Rates of toxicities were then compared between the cohort of patients who received CF and those who HF using the Chi-square test.

RESULTS

Of the 1051 patients, 450 (43%) received CF and 601 (57%) received HF. These patients were treated by 40 different radiation oncologists (median patients per physician = 18, interquartile range = 7-35). Median age in the CF and HF cohorts was 71 (IQR: 66-76) and 71 (IQR: 66-77; p = 0.51), respectively. The CF cohort had more patients with Gleason 8+ disease (39% vs 19%; p<0.01), PSA >20 (26% vs 11%; p<0.01), or T3a+ (18% vs 8%; p<0.01). Rates of any grade 2+ toxicity were significantly higher in patients who received HF at 45.8% vs 39.6% for those treated with CF (p = 0.04). However, the respective rates of any grade 3+ toxicity were no different at 2.0% vs. 1.8% (p = 0.80). The difference in grade 2 toxicities appeared to be primarily driven by the rates of urinary frequency at 27.1% vs. 17.8% (p<0.01) and prostatic obstruction 14.8% vs. 10.2%, p = 0.03). Rates of grade 2 diarrhea were worse with MF at 5.3% vs. 2.8% for CF (p = 0.04). There were no significant differences between HF and CF in the rates of grade 2 dysuria (6% vs 5.2%), urinary urgency (6.5% vs. 4.2%), proctitis (3.0% vs. 3.6%), urinary incontinence (0.5% vs. 1.3%), rectal bleeding (0.3% vs. 0%), hematuria (0% vs. 0.4%), and fatigue (14.1% vs. 15.1%).

CONCLUSION

In this large network-wide analysis, toxicity was slightly increased among patients with prostate cancer treated with HF compared to CF, consistent with published randomized data. However, the increased toxicity appeared to be primarily GU rather than GI. This study demonstrates the feasibility of analyzing impacts of treatment decisions on a large scale using real-world data through an integrated network of practices.

Evaluation of 68Ga-Fibroblast Activation Protein Inhibitor vs. 18F-FDG as a Novel Radiotracer for Biologically Guided Radiation Therapy

PURPOSE/OBJECTIVE(S)

Real-time biology guided radiation therapy (BgRT) uses real-time positron emissions from a PET tracer during treatment to guide targeted radiation to cancerous lesions. Fibroblast activation protein alpha (FAP) is highly expressed on cancer-associated fibroblasts in tumors with low expression in normal tissues. While 18F-FDG-PET requires fasting and has background in the liver and brain, 68-Gallium labeled FAP inhibitor (FAPI) does not require fasting and has less background uptake. The goal of this study was to investigate the utility of FAPI as a potential universal fiducial for BgRT. We hypothesized that 68Ga-FAPI would be a better radiotracer than 18F-FDG, as assessed by the Normalized Minimal kBq/mL and the Normal Target Signal (NTS), two parameters used to gauge the suitability of BgRT.

MATERIALS/METHODS

PET-CTs were obtained for 50 patients with pancreatic, liver, lung, head & neck, and cervical cancer using 18F-FDG and 68Ga-FAPI (n = 10 for each). Four DICOM images were obtained per patient (FDG PET + CT, FAPI PET + CT). Radiation oncologists delineated the gross tumor volume (GTV) on PET images. A separate set of auto-contours were generated from the PET using an auto-threshold of 40% maximum SUV for all tumors. A 1 cm expansion was added to the GTV to create a ring around the physician-generated contours and auto-contours. The following parameters were measured: GTV volume, SUV max of GTV, SUV mean of GTV, Normalized Minimal kBq/mL within the GTV, and NTS (= SUV max/Ring SUV mean). Values were compared using paired t-test. For the BgRT product with similar calculations, the required Normalized Minimal kBq/mL is > 5 kBq/mL; the required NTS is > 2.7 for treatment planning and > 2.0 for BgRT delivery.

RESULTS

The Normalized Minimal kBq/mL for FAPI was > 5 kBq/mL for all tumors and greater for auto-contoured GTVs compared to physician-contoured GTVs. The mean NTS for the auto-contours for all tumor sites was > 2.0. In addition, there was a statistically significant increase in the NTS for FAPI compared to FDG in pancreatic, liver and head & neck cancers. In pancreatic cancer, there was a statistically significant increase in Normalized Minimal kBq/mL for FAPI compared to FDG (26.0 vs 14.2) (p = 0.01) and the SUVmax of FAPI was almost double that of FDG (15.9 vs 8.2) (p = 0.01). FAPI had no background in the liver, but had high background in the uterus, suggesting it may have a role in liver cancer but not cervical cancer.

CONCLUSION

This is the first study demonstrating the potential superiority of 68Ga-FAPI compared to 18F-FDG as a biologic fiducial for BgRT when treating pancreatic, liver and head & neck cancers, with a similar efficacy for lung cancer. Our results indicate that auto-contoured GTVs generate a higher NTS than physician-contoured GTVs but all are > 2.0. In addition, the Normalized Minimal kBq/mL for auto-contours is > 5 kBq/mL for all tumors. As hypothesized, FAPI-based BgRT is most likely to be successful when treating tumors with significant desmoplastic stroma, such as pancreatic cancer.

Spatiotemporal Optimization of Pelvic Radiation Therapy

PURPOSE/OBJECTIVE(S)

Conformal and adaptive Radiation Therapy (RT) remains critical in the treatment of locally advanced pelvic cancers despite acute and late bowel complications. This work introduces spatiotemporal optimization of pelvic RT including mathematical modelling of intestinal radiobiology to evaluate a novel treatment planning approach for fractionated pelvic RT.

MATERIALS/METHODS

A single-plan fractionated RT delivery has n-fractions at dose/fraction = d and has biologically effective dose BED = nd ( 1 + d / [α/β] ) - ln(2) ([T - Tk] / [αTp]), where Tk and Tp are the kickoff time and doubling time of repopulation, and T is the time to deliver all fractions (including off-days). We present a parameterization of the repopulation BED-term to estimate a range of daily recovered BED including uncertainties in α and Tp. Recovery of BED as currently formulated is independent of the delivered dose; however, the assumption of spatiotemporal optimization is that a regional reduction of dose during RT by mixing treatment plans is critical to allow for normal tissue healing. We evaluate an achievable spatiotemporal optimization treatment planning strategy for an advanced stage prostate and a cervical cancer patient using 25-fraction delivery over 5-weeks and 4-weekends (T = 33 days) and propose 3 treatment plans: (1) a conformal "clinical standard" plan, (2) a right-bowel sparing plan, and (3) a left-bowel sparing plan. The plans are optimized to ensure no increased dose in opposing bowel or normal organs at risk (OARs).

RESULTS

For radiobiological parameters ranging from α = 0.2-0.35/Gy, α/β = 2-3 Gy, Tk = 5-10 days, and Tp = 3-7 days, parameterization shows daily BED recovery of 0.44±0.08 Gy (range = 0.28-0.69 Gy), or an average of 4Gy BED recovery for 5-days treatment surrounded by 2 weekends. Conservatively evaluating the 3.6Gy BED distribution in treatment planning may identify regions for complete recovery (after Tk days). In a prostate 3-plan set, the right- and left- bowel sparing plans deliver equivalent mean dose to targets and OARs to within 5cGy/fx. The clinical plan includes 298cc of bowel under 14Gy, but this same bowel will be spared throughout treatment. Delivery of the clinical plan in week 1 to achieve Tk days, followed by alternating the left and right plan each week has the potential to reduce BED to zero for an additional 116cc of bowel using the left-sparing plan in weeks 2 and 4, and 91cc using the right-bowel sparing plan in weeks 3 and 5. The cervical cancer plan-set was more challenging due to right-sided nodal volumes and higher clinical bowel dose; OAR mean dose variations were >8cGy/fx in a few organs, but the left- and right- sided sparing plans results in 394 cc and 139cc, respectively of unique spared bowel at the 3.6Gy/week threshold to potentially reach zero BED during treatment.

CONCLUSION

A novel spatiotemporal optimization of pelvic RT has the potential to preserve bowel, allow for increased intra-treatment intestinal tissue regeneration, and reduce radiation-induced complications.

Pilot Study of a Novel Ring Gantry-Based PET/CT Linear Accelerator in Patients with Prostate Cancer Receiving [18F]-DCFPyL for PSMA PET Imaging

PURPOSE/OBJECTIVE(S)

The RefleXion X1® system is a hybrid PET imaging-radiotherapy system that uses real-time positron emissions from a PET tracer to deliver biologically guided radiotherapy (BgRT). This study (NCT05470699) evaluated the hypothesis that the X1 PET imaging subsystem would be able to detect [18F]-DCFPyL PSMA PET signal sufficient to generate a deliverable BgRT plan in patients with prostate cancer.

MATERIALS/METHODS

Patients with prostate cancer scheduled for a diagnostic [18F]-DCFPyL PSMA PET scan as part of standard of care were eligible. Upon completion of the diagnostic PSMA PET scan, images were transferred to the radiotherapy planning system for target identification and contouring. If at least one PET avid tumor lesion was identified, the patient was then scanned on the X1 unit. BgRT planning was performed on each X1 scanned patient. The target lesion volume, activity concentration (AC) and normalized target signal (NTS) were acquired. Successful and deliverable BgRT plans required that the target AC was ≥ 5 kBq/ml and NTS ≥ 2.7.

RESULTS

Twenty-six patients underwent [18F]-DCFPyL PET scans (13 with rising PSA after surgery or radiotherapy, 6 with known metastases and 7 with newly diagnosed high-risk prostate cancer). Median (range) PSA was 3.40 (0.04-122). In 16 patients a PET avid tumor was identified and contoured for planning (4 lymph nodes, 5 bone, 6 prostate gland, and 1 prostate bed). In 13 patients the target lesion was visualized on the X1 PET scan, while in 3 patients the target lesion was too close to the bladder to be clearly visualized. BgRT planning was feasible and met standard of care published SBRT organ dose constraints in 8 patients (3 prostate gland, 3 bone, 2 lymph nodes). BgRT planning was not feasible in 8 patients due to insufficient AC, low NTS or proximity of the target lesion to the PET avid bladder. The accompanying table compares median (range) target volume, AC and NTS for feasible versus not feasible plans.

CONCLUSION

This is the first study to investigate the feasibility of using [18F]-DCFPyL PET imaging for BgRT plan generation on the X1 system in patients with prostate cancer. Lesions that are relevant to radiotherapy of prostate cancer can be visualized including lymph node and bone metastases. A dedicated BgRT workflow with PSMA PET imaging on the X1 at 60 minutes post injection will result in higher target AC and will optimize BgRT planning. PET avid lesions < 1 cm or close to the bladder may make BgRT planning challenging. [18F]-DCFPyL-guided BgRT is technically feasible using the RefleXion X1. BgRT using targeted PET radiopharmaceuticals to biologically guide external beam radiotherapy represents a promising new dimension in radiation oncology and warrants further investigation.

Are All Prognostic Stage IB Breast Cancers Equivalent?

PURPOSE/OBJECTIVE(S)

The 8th edition of the American Joint Committee on Cancer (AJCC) has recognized the prognostic influence of histologic grade and biomarker status for breast cancer (BC). Contemporary BC staging includes both anatomic tumor extent and prognostic stage. However, prognostic stage IB remains heterogeneous and includes patients with locally advanced anatomic pathologic stage IIIA-B (pT3N1 or pT1-3N2, G1-2) hormone-receptor positive/HER2-negative BC (LA-HR+/HER2-) as well as patients with early-stage anatomic clinical/pathologic stage IA (T1cN0, G2-3) triple-negative BC (ES-TNBC). We hypothesized that although both are classified as prognostic stage IB BC, overall survival (OS) is worse for LA-HR+/HER2- compared to ES-TNBC.

MATERIALS/METHODS

We used the National Cancer Database to identify patients with surgically-resected LA-HR+/HER2- BC (pT3N1 or pT1-3N2, grade 1-2) and those with ES-TNBC (T1N0, grade 2-3) from 2004-2017. Patients were excluded if receptor status, tumor grade, and/or TNM staging data were unknown. HR+/HER2- patients treated with neoadjuvant therapy were also excluded. The primary endpoint was OS. Multivariable Cox regression analysis was used to evaluate differences in OS between LA-HR+/HER2- BC and ES-TNBC (adjusting for baseline patient demographic characteristics) in the entire cohort and in the subset of patients that received appropriate treatment based on anatomic stage: radiation (RT), chemotherapy (CT) and hormone therapy for LA-HR+/HER2- BC and CT or CT+RT for ES-TNBC treated with mastectomy or lumpectomy, respectively. We report hazard ratios (HR) with 95% confidence intervals (CI) with p<0.05 considered statistically significant.

RESULTS

A total of 45,818 patients met inclusion criteria (N = 17,359 with LA-HR+/HER2- BC and N = 28,459 with ES-TNBC). Over 75% of the LA-HR+/HER2- BC patients have anatomic pathologic stage IIIB disease (pT1-3N2, G1-2). With a median follow-up of 56 months, the 6-year OS rates were 86.1% (LA-HR+/HER2-) vs. 90.4%patients (ES-TNBC) which corresponded to a 63% relative increased risk of death in LA-HR+/HER2- patients compared to ES-TNBC patients (HR = 1.63, 95% CI 1.53-1.73, p<0.0001) after adjusting for all covariates. Approximately 66% (N = 11,533) LA-HR+/HER2- and 69% (N = 19,512) ES-TNBC received appropriate therapy. The 6-year OS was 91.8% (LA-HR+/HER2-) vs. 93.3% (ES-TNBC) which corresponded to a 35% increased risk of death in the LA-HR+/HER2- patients compared to ES-TNBC (adjusted HR = 1.35, 95% 1.24-1.48, p<0.0001). Other covariates associated with OS were age, income, insurance status, facility type, and ethnicity/race.

CONCLUSION

We found that LA-HR+/HER2- BC has significantly worse OS compared to ES-TNBC despite both being classified as prognostic stage IB, even when accounting for treatments delivered. The categorization of pT3N1 or pT1-3N2, G1-2 HR+/HER2- BC as prognostic stage IB needs to be reconsidered in order to provide patients with more accurate information regarding expected OS.

Omission of Adjuvant Radiotherapy in Low-Risk Elderly Males with Breast Cancer

PURPOSE/OBJECTIVE(S)

Randomized clinical trials demonstrate that lumpectomy + hormone therapy (HT) without radiation therapy (RT) yields equivalent survival and acceptable local-regional outcomes in elderly women with early-stage, node-negative (T1-2N0) hormone-receptor positive (HR+) breast cancer. Whether these data apply to men with the same inclusion criteria remains unknown. We hypothesized that outcomes in males would be comparable to those seen in females, with RT not conferring an overall survival (OS) benefit over HT alone.

MATERIALS/METHODS

We conducted a retrospective matched-cohort study using the National Cancer Database for males ≥65 years with pathologic T1-2N0 (≤3 cm) HR+ breast cancer treated with breast conserving surgery with negative margins from 2004-2019. Patients who received chemotherapy, had nodal or distant metastases, or unknown follow-up were excluded. Adjuvant treatment was classified as HT alone, RT alone, or HT+RT. Due to limitations of survival analysis on retrospective data, male patients were matched with female patients to determine comparable outcomes based on age (± 3 years), Charlson Deyo comorbidity score, T-stage, and adjuvant treatment. Survival analysis was performed using Cox regression and Kaplan-Meier analysis. To adjust for confounding, inverse probability of treatment weighting (IPTW) was used.

RESULTS

A total of 523 patients met inclusion criteria, with 24.4% receiving HT, 16.3% receiving RT, and 59.2% receiving HT+RT. Median follow-up was 6.9 years (IQR: 5.0-9.4 years). Unadjusted 5-yr OS rates in the HT, RT, and HT+RT cohorts were 79.2% (95% CI 70.7-85.5%), 80.9% (95% CI 70.3-88.0%), and 93.3% (95% CI 89.7-95.7%), respectively. Adjusted 10-yr OS rates in the HT, RT, and HT+RT cohorts were 82.3% (95% CI 78.6-85.5%), 83.6% (95% CI 80.0-86.7%), and 92.8% (95% CI 90.1-94.8%), respectively. On unadjusted multivariable Cox regression analysis (MVA), relative to HT, receipt of HT+RT was associated with improvements in OS (HR: 0.603; 95% CI: 0.410-0.888; p = 0.01). RT alone was not associated with improved OS (HR: 1.116; 95% CI: 0.710-1.755; p = 0.633). On adjusted MVA, relative to HT, receipt of HT+RT was associated with improvements in OS (HR: 0.551; 95% CI: 0.370-0.820; p = 0.003). Again, RT alone was not associated with improved OS (HR: 0.991; 95% CI: 0.613-1.604; p = 0.972). Other factors associated with OS included age, Charlson Deyo score, T stage, and grade. Overall, in the matched women, the same trends were found as in the men, the best survival was in HT+RT, but no difference in OS between HT vs. RT.

CONCLUSION

Among men ≥65 years old with T1-2N0 HR+ breast cancer, RT alone did not confer an OS benefit over HT alone. Combined RT+HT did yield improvements in OS, though there are likely significant unmeasured confounders contributing to these outcomes in patients treated with the most aggressive approach. Our findings support that RT omission may be a reasonable option in elderly men with T1-2N0 HR+ breast cancer treated with lumpectomy + HT.

Dosimetric Plan Evaluation of Biology Guided Radiotherapy Using [18F]-DCFPyL PSMA Radiotracer in Patients with Prostate Cancer

PURPOSE/OBJECTIVE(S)

The X1 system represents a cutting-edge solution in radiotherapy delivery, with its capability to perform Biology Guided Radiotherapy (BgRT). The system utilizes real-time positron emission tomography (PET) signal as biological fiducials to provide tracked dose delivery and is initially available for use with [18F]-Fluorodeoxyglucose (FDG). The aim of this research study is to assess the quality of BgRT treatment plans for prostate cancer using patients' PSMA PET images obtained on the X1 system.

MATERIALS/METHODS

Sixteen patients with at least one PET-avid tumor identified on their whole-body diagnostic PSMA PET scan were selected. These patients were scanned on X1 following their diagnostic scan without additional radiotracer administration. Based on the X1 PET images, a BgRT plan was created for each patient, with the prescription dose determined by the location of treatment sites. The planning objectives of organs-at-risk (OARs) were established in accordance with the 2018 Timmerman guidelines. Target coverage objective was the dose covering 95% (D95%) of the planning target volume (PTV) to be higher than 100%. The following parameters were analyzed: PTV D95%, the minimal dose (Dmin) of gross tumor volume (GTV), plan maximum dose (Dmax), conformity index (CI), gradient index (GI), and maximum point dose (D0.03cc) to the nearest OARs. The X1 BgRT planning system also generated dose volume histogram (DVH) bounds, which model variations in BgRT delivery. The low boundary of GTV Dmin, representing the minimum GTV dose in the worst-case scenario, was recorded.

RESULTS

BgRT plans were created for all patients, except for one where the target signal was indistinguishable from the bladder. The prescription dose was 2700 cGy or 3000 cGy in 3 fractions for lymph node lesions, 2400 cGy to 3000 cGy in 3 fractions for bone metastasis, and 4500 cGy in 5 fractions for lesions in prostate. All plans met the dose constraints for OARs as per the Timmerman guidelines. The Dmax of all plans was 129.9% ± 6.9% (mean ± standard deviation). The PTV D95% and GTV Dmin were 101.7% ± 1.0% and 111.0% ± 7.6%, respectively. The low boundary of GTV Dmin was 95.9% ± 5.8%. The CI and GI were 1.22 ± 0.11 and 9.40 ± 2.12, respectively. The D0.03cc to nearest OARs was 84.6% ± 25.4%. The estimated treatment time was 699 ± 228 seconds.

CONCLUSION

This study is a pioneering effort to evaluate the quality of BgRT plans for prostate cancer patients using the [18F]-DCFPyL PSMA radiotracer. Our results showed that all BgRT plans met the planning objectives defined in the Timmerman protocol. BgRT with [18F]-DCFPyL represents a promising treatment modality for patients with prostate cancer. Further research is needed to validate this approach, including a comprehensive assessment of the dosimetric and tracking accuracy through physical measurements.

Machine Learning and Explainable Artificial Intelligence to Predict Occult Pelvic Nodal Metastases in Prostate Cancer

PURPOSE/OBJECTIVE(S)

Determination of risk of occult pelvic lymph node involvement (LNI) in patients with cN0 prostate cancer is critical for determination of optimal treatment options. Though several nomograms exist, machine learning (ML) approaches might enable physicians to better assess individual risk by incorporating multiple clinical risk factors. Herein, we developed a ML model to predict occult LNI, and explained its composition using an explainable artificial intelligence (XAI) framework.

MATERIALS/METHODS

Patients with cN0 prostate adenocarcinoma diagnosed from 2018-2020 were identified in the National Cancer Database. The query was limited to patients with known clinical staging and biopsy results who did not receive neoadjuvant therapy prior to pelvic nodal examination. Occult LNI was defined as pN1 disease based on surgical evaluation, with a minimum of 10 nodes examined. Five ML models were trained to predict LNI. Variables incorporated into the model were age, core biopsy results, Gleason scores, preoperative prostate specific antigen (PSA), and clinical T-stage. Model performance, measured using area under the receiver operator characteristic curve (AUC) on a holdout testing dataset, was compared to multivariable logistic regression. The best-performing model was explained using SHapley Additive exPlanation (SHAP) values. To permit more clinically-meaningful statistical interpretation, using a novel approach SHAP values were converted into odds ratios (OR), confidence intervals (CI), and p-values.

RESULTS

A total of 23,131 patients met inclusion criteria; 2,676 (11.6%) had occult LNI. The Extreme Gradient Boosting model outperformed all other models with an AUC of 0.82 (95% CI: 0.78-0.86) compared to 0.80 (95% CI: 0.76-0.84) for logistic regression. Increasing PSA (OR: 1.031; p<0.001), number of positive biopsy cores (OR: 1.055; p<0.001), and percent positive biopsy cores (OR: 1.01; p<0.001) were all associated with increased risk of LNI. Based on observation of SHAP dependence plots, risk of LNI plateaued at PSA>20 ng/dL and >11 positive cores, while no plateau was observed for percent positive biopsy cores. Relative to T1c disease, patients with T3b were at highest risk of LNI (OR: 1.461; p = 0.003). Gleason score of 9 was associated with significant risk of LNI (Ref: Gleason 6; OR: 1.891; p<0.001). This was primarily driven by the primary Gleason score; primary Gleason 5 disease was associated with significant risk of LNI (Ref: Gleason 3; OR: 1.915; p<0.001) while a secondary Gleason score of 5 was the only grade with significant increased risk of LNI (Ref: Gleason 3; OR: 1.185; p = 0.004). Age and number of cores examined were not significant predictors of LNI.

CONCLUSION

Our ML achieved improved performance relative to logistic regression at predicting occult LNI. XAI provided insight into the inner-working of the ML model. ML can be used to identify patients at risk for occult LNI and therefore inform clinical decision-making.

Patterns of Care for Patients with Locally Advanced Rectal Cancer Treated with Total Neoadjuvant Therapy between 2016-2020: An NCDB Analysis

PURPOSE/OBJECTIVE(S)

Treatment for locally advanced rectal cancer (LARC), defined as T3/4 or any T with N+ disease, typically requires multi-modality management consisting of radiation (RT), chemotherapy (CHT), and surgery. Despite emerging evidence that total neoadjuvant therapy (TNT) is the preferred treatment of LARC, it remains unknown what proportion of patients are receiving TNT in the United States. Our objective was to (1) determine the proportion of patients with LARC receiving TNT over time, (2) determine the most common method in which TNT is being delivered, and (3) determine what factors are associated with a lower likelihood of receiving TNT in the United States.

MATERIALS/METHODS

Retrospective data was obtained from the National Cancer Database (NCDB) for patients diagnosed with rectal cancer between 2016-2020. Patients were excluded if they had M1 disease, T1-2 N0 disease, incomplete staging information, non-adenocarcinoma histology, received RT to a non-rectum site, or received a non-definitive RT dose. Patients were determined to have received TNT if they (1) received RT and multi-agent (MA)-CHT prior to surgery, (2) had an interval of >180 days from the onset of neoadjuvant therapy to surgery if they received long course (LC)-chemoradiation (CRT) (based on 35 days for LC-CRT + 112 days for 8 cycles of MA-CHT + 30 days to surgery), or (3) had an interval of >150 days from the onset of neoadjuvant therapy to surgery if they received short course (SC)-RT (based on 5 days for SC-RT + 112 days for 8 cycles of MA-CHT + 30 days to surgery). Data were analyzed using linear regression, Chi-square test, and binary logistic regression.

RESULTS

Of the 26,375 patients included, the median age was 60 (range 21-90) years, with the majority of patients being <65 years old (65.6%), male (62.1%), and non-Hispanic white (77.0%). A total of 5,003 (19.0%) patients received TNT, and 21,372 (81.0%) patients received classical combined modality therapy (CMT). The proportion of patients receiving TNT increased significantly over time, from 6.1% in 2016, 9.0% in 2017, 15.3% in 2018, 25.8% in 2019, to 34.6% in 2020 (slope = 7.36, 95% CI 4.58-10.15, R2 = 0.96, p = 0.040). The most common TNT regimen was MA-CHT followed by LC-CRT (73.2% of cases from 2016-2020). The proportion of patients receiving SC-RT as part of TNT significantly increased from 2.8% in 2016, 1.7% in 2017, 4.6% in 2018, 7.3% in 2019, to 13.7% in 2020 (slope = 2.74, 95% CI 0.37-5.11, R2 = 0.82, p = 0.035). On multivariate analysis, factors associated with a lower likelihood of TNT use included age >65 (OR 0.66, 95% CI 0.61-0.71, p<0.001), female gender (OR 0.92, 95% CI 0.86-0.98, p = 0.014), Black race (OR 0.87, 95% CI 0.77-0.98, p = 0.024), and T3 N0 disease (OR 0.60, 95% CI 0.52-0.70, p<0.001).

CONCLUSION

TNT utilization rates have significantly increased in recent years, from 6.1% in 2016 to 34.6% in 2020. The observed trend appears to be in line with the recent National Comprehensive Cancer Network (NCCN) guidelines recommending TNT as the preferred approach.

Discovery and characterization of prolactin neutralizing monoclonal antibodies for the treatment of female-prevalent pain disorders

Prolactin (PRL) has recently been demonstrated to elicit female-selective nociceptor sensitization and increase pain-like behaviors in female animals. Here we report the discovery and characterization of first-in-class, humanized PRL neutralizing monoclonal antibodies (PRL mAbs). We obtained two potent and selective PRL mAbs, PL 200,031 and PL 200,039. PL 200,031 was engineered as human IgG1 whereas PL 200,039 was reformatted as human IgG4. Both mAbs have sub-nanomolar affinity for human PRL (hPRL) and produce concentration-dependent and complete inhibition of hPRL signaling at the hPRL receptor (hPRLR). These two PRL mAbs are selective for hPRL as they do not inhibit other hPRLR agonists such as human growth hormone or placental lactogen. They also cross-react with non-human primate PRL but not with rodent PRL. Further, both mAbs show long clearance half-lives after intravenous administration in FcRn-humanized mice. Consistent with their isotypes, these mAbs only differ in binding affinities to Fcγ receptors, as expected by design. Finally, PL 200,019, the murine parental mAb of PL 200,031 and PL 200,039, fully blocked stress-induced and PRL-dependent pain behaviors in female PRL-humanized mice, thereby providing in vivo preclinical proof-of-efficacy for PRL mAbs in mechanisms relevant to pain in females.

A Human IgSF Cell-Surface Interactome Reveals a Complex Network of Protein-Protein Interactions

Cell-surface protein-protein interactions (PPIs) mediate cell-cell communication, recognition, and responses. We executed an interactome screen of 564 human cell-surface and secreted proteins, most of which are immunoglobulin superfamily (IgSF) proteins, using a high-throughput, automated ELISA-based screening platform employing a pooled-protein strategy to test all 318,096 PPI combinations. Screen results, augmented by phylogenetic homology analysis, revealed ∼380 previously unreported PPIs. We validated a subset using surface plasmon resonance and cell binding assays. Observed PPIs reveal a large and complex network of interactions both within and across biological systems. We identified new PPIs for receptors with well-characterized ligands and binding partners for “orphan” receptors. New PPIs include proteins expressed on multiple cell types and involved in diverse processes including immune and nervous system development and function, differentiation/proliferation, metabolism, vascularization, and reproduction. These PPIs provide a resource for further biological investigation into their functional relevance and may offer new therapeutic drug targets.

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Human IgSF interactome reveals complex network of cell-surface protein interactions

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Phylogenetic homology analysis predicts protein-protein interactions

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∼380 previously unknown protein-protein interactions identified

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Deorphanization of receptors and new binding partners for well-studied receptors

Complications of intracavitary brachytherapy for gynecologic cancers and their management: A comprehensive review

Intracavitary gynecologic brachytherapy in the form of tandem-based brachytherapy and vaginal cylinder-based brachytherapy represents a fundamental component of the treatment of women with cervical or uterine cancer due to the ability to deliver a therapeutic dose of radiation with sharp dose falloff. This results in highly effective treatment in terms of oncologic outcomes with an overall favorable toxicity profile. Still, complications and side effects of brachytherapy do exist. While advances in brachytherapy techniques have led to a significant decrease in the rates of toxicity, a thorough understanding of the potential complications is crucial to ensuring optimal outcomes for women with gynecologic cancer undergoing brachytherapy. Use of equivalent dose at 2 Gy per fraction (EQD2) models has allowed incorporation of external beam radiotherapy dose to the brachytherapy dose leading to development of consolidated dose constraints for organs-at-risk in the modern era. This manuscript offers a comprehensive review of potential complications associated with intracavitary brachytherapy for gynecologic cancer including predictive factors, mitigation tactics, and management strategies.

Treatment selection and survival outcomes in Early-Stage peripheral T-Cell lymphomas: does anaplastic lymphoma kinase mutation impact the benefit of consolidative radiotherapy?

The role of consolidative radiotherapy (RT) is less substantiated in uncommon peripheral T-cell lymphomas (PTCLs). Anaplastic lymphoma kinase (ALK) mutation sub-categorizes PTCLs, with ALK (+) having a distinctly favorable prognosis. We aimed to use the National Cancer Database to examine the potential role of RT in PTCLs and if ALK mutation can be used to predict the benefit of consolidative RT after multi-agent chemotherapy (combined modality therapy). We identified 3670 stage I-II PTCL patients treated with multi-agent chemotherapy alone or combined modality therapy (CMT) between 1998-2012. After adjusting for immortal-time and indication bias, CMT was associated with better OS than multi-agent chemotherapy alone for ALK (-) patients (HR 0.69, 95% CI 0.52-0.92, p = .01); no significant difference was noted for ALK (+) (HR 1.03, 95% CI 0.75-1.41, p = .85). CMT is associated with improved OS for ALK (-) PTCLs; while no such benefit was seen for the ALK (+) subgroup.

Race-driven survival differential in women diagnosed with endometrial cancers in the USA

OBJECTIVE

African American women are increasingly being diagnosed with advanced and type II histology endometrial cancers. Outcomes have been observed to be worse in African American women, but whether or not race itself is a factor is unclear. We sought to evaluate the rates of diagnosis and outcomes on a stage-by-stage basis with respect to race using a large national cancer registry database.

METHODS

The National Cancer Data Base was searched for patients with surgically staged non-metastatic endometrial cancer between 2004 and 2015. Women were excluded if surgical stage/histology was unknown, there was no follow-up, or no information on subsequent treatment. Pairwise comparison was used to determine temporal trends and Cox hazards tests with Bonferroni correction were used to determine overall survival.

RESULTS

A total of 286 920 women were diagnosed with endometrial cancer and met the criteria for analysis. Median follow-up was 51 months (IQR 25.7-85.3). In multivariable models, in women with stage I disease, African American women had a higher risk of death than Caucasian women (HR 1.262, 95% CI 1.191 to 1.338, p<0.001) and Asian/Pacific Islander women had a lower risk of death than Caucasian women (HR 0.742, 95% CI 0.689 to 0.801, p<0.001). This held for African American women with stage II type I and type II disease (HR 1.26, 95% CI 1.109 to 1.444, p<0.001 and HR 1.235, 95% CI 1.098 to 1.388, p<0.001) but not for Asian/Pacific Islander women. African American women with stage IIIA-B disease also had a higher risk of death for type I and type II disease versus Caucasian women (HR 1.221, 95% CI 1.045 to 1.422, p=0.010 and HR 1.295, 95% CI 1.155 to 1.452, p<0.001). Asian/Pacific Islander women had a lower risk of death than Caucasian women with type I disease (HR 0.783, 95% CI 0.638 to 0.960, p=0.019) and type II disease (HR 0.790, 95% CI 0.624 to 0.999, p=0.05). African American women with stage IIIC1-2 had a higher risk of death with type I disease (HR 1.343, 95% CI 1.207 to 1.494, p<0.001) and type II disease (HR 1.141, 95% CI 1.055 to 1.233, p=0.001) whereas there was no significant difference between Caucasian women and Asian/Pacific Islander women.

CONCLUSION

Race appears to play an independent role in survival from endometrial cancer in the USA, with African American women having worse survival on a stage-for-stage basis compared with Caucasian women.

Declining brachytherapy utilization for cervical cancer patients - Have we reversed the trend?

OBJECTIVE

Studies examining temporal trends in cervical brachytherapy use are conflicting and examined different health insurance populations. This study examined brachytherapy utilization over time by health insurance type and whether reported declines in brachytherapy have reversed.

METHODS

The National Cancer Database (NCDB) was queried for patients with FIGO IIB-IVA cervical cancer treated with definitive chemoradiotherapy between 2004 and 2014, identifying 17,442 patients. Brachytherapy utilization over time and by insurance type and other sociodemographic factors were compared using binary logistic regression. A sensitivity analysis was done in a sub-cohort of patients using the boost modality variable in the NCDB.

RESULTS

Brachytherapy utilization declined during 2008-10 (52.6%) compared to 2004-2007 (54.4%; odds ratio [OR] 0.93, 95% confidence interval [CI] 0.86-1.01) and declines were disproportionately larger for patients with government insurance (49.4% vs 52.3%, respectively) than privately-insured patients (57.6% vs 58.9%, respectively). However, rates of brachytherapy use subsequently recovered during 2011-14 in all insurance groups (58.0%, OR 1.24, 95% CI 1.16-1.34) and was especially improved for Medicaid (OR 1.44, 95% CI 1.26-1.65) and uninsured patients (OR 1.28, 95% CI 1.03-1.57). Sensitivity analysis using the boost modality variable confirmed these trends.

CONCLUSIONS

In patients with FIGO IIB-IVA cervical cancer treated with definitive chemoradiotherapy from 2004 to 2014, brachytherapy utilization declined during the late 2000s and disproportionately affected patients with government insurance, but subsequently recovered in the early 2010s. Since government insurance covers vulnerable patient populations at-risk for future declines in brachytherapy use, proposed alternative payment models should incentivize cervical brachytherapy to solidify gains in brachytherapy utilization.

Drivers of 30- and 90-day Postoperative Death After Neoadjuvant Chemoradiation for Esophageal Cancer

BACKGROUND

Neoadjuvant chemoradiation, followed by esophagectomy, is a standard of care for locally advanced esophageal cancers. The ChemoRadiOtherapy plus Surgery versus Surgery alone (CROSS) trial reported a 30-day mortality rate of 6%. We sought to evaluate 30- and 90-day mortality in similar patients in the United States and identify predictors of higher mortality rates.

METHODS

The National Cancer Database was used to identify patients with cT3-4/N+ esophageal cancers treated with neoadjuvant chemoradiation followed by esophagectomy. Bivariate univariable and multivariable regression analysis was used to identify predictors of 30- and 90-day mortality.

RESULTS

We identified 7691 patients. Readmission within 30 days of surgery occurred in 6.0% of patients. Mortality was 2.9% at 30 days and 7.2% at 90 days. Positive surgical margins conferred a more than doubled risk of 30- and 90-day mortality, 5.5% vs 2.7% and 14.6% vs 6.8% (both P < .001). Facility surgical volume impacted 30-day mortality, whereas readmission was associated with 90-day mortality, both exceeding 10% (P = .004 and P = .001, respectively). In patients undergoing minimally invasive surgery converted to open, 90-day mortality was 12.1% (P < .01). For patients 69 years and older, 90-day mortality was also 12.1% (P < .001). Patients who underwent esophagectomy more than 45 days from completion of chemoradiation also had higher 90-day mortality at 8.3% vs 6.2% (P < .001).

CONCLUSIONS

Postoperative death at 30 and 90 days after neoadjuvant chemoradiation and esophagectomy appears to be on par with randomized data. Positive surgical margins, squamous cell carcinomas, age 69 and older, readmission within 30 days, and conversion from a minimally invasive operation to an open operation all carry a 90-day mortality risk exceeding 10%.

Early mortality of stage IV non-small cell lung cancer in the United States

Background: Early mortality is a major deterrent to oncologic management, often preventing delivery of therapy or leading to administration of treatment that offers limited benefit from aggressive interventions. Due to more recent progress in therapeutic options for stage IV non-small cell lung cancer (NSCLC) patients, identifying those at high risk of early mortality (within 30 days) could have implications for treatment selection. Because early mortality following diagnosis of metastatic non-small cell lung cancer (NSCLC) is not well-characterized, this investigation evaluated national trends and predictors thereof. Material and methods: The National Cancer Database was queried for cases of pathologically confirmed metastatic NSCLC with complete vital status and clinical information, diagnosed between 2006 and 2014. Multivariable logistic regression ascertained factors associated with 30-day mortality. Results: Of 346,681 patients, 45,861 (13%) experienced early mortality over the past decade, which remained relatively constant over time. Predictors of early mortality included advancing age (>65 years), male gender, Caucasian race, non-private insurance, lower income, greater comorbidities, residence in metropolitan and/or lesser-educated areas, treatment at community centers, patients with no prior history of cancer and regional differences (p < .01 for all). Early mortality was highest in patients older than 80 years with multiple comorbidities (29%). The majority of patients (71%) who died within 30 days did not receive any therapy. Conclusions: A fair proportion of NSCLC patients experience early mortality, which has not decreased over time. The majority of patients with early mortality do not receive treatment. Prognostic factors for early mortality should be considered during initial evaluation and subsequent follow-up of these patients. Doing so may impact systemic treatment selection by medical oncologists, management of (oligo)metastatic disease by radiation and surgical oncologists and cost-effective administration of these therapies in the stage IV NSCLC population.

A High-Throughput System for Transient and Stable Protein Production in Mammalian Cells

Recombinant protein expression and purification is an essential component of biomedical research and drug discovery. Advances in automation and laboratory robotics have enabled the development of highly parallel and rapid processes for cell culture and protein expression, purification, and analysis. Human embryonic kidney (HEK) cells and Chinese hamster ovary (CHO) cells have emerged as the standard host cell workhorses for producing recombinant secreted mammalian proteins by using both transient and stable production strategies. In this chapter we describe a fully automated custom platform, Protein Expression and Purification Platform (PEPP), used for transient protein production from HEK cells and stable protein production from CHO cells. Central to PEPP operation is a suite of custom robotic and instrumentation platforms designed and built at GNF, custom cell culture ware, and custom scheduling software referred to as Runtime. The PEPP platform enables cost-effective, facile, consistent production of proteins at quantities and quality useful for early stage drug discovery tasks such as screening, bioassays, protein engineering, and analytics.

Outcomes after definitive re-irradiation with 3D brachytherapy with or without external beam radiation therapy for vaginal recurrence of endometrial cancer

BACKGROUND

Limited outcome data exists on salvage re-irradiation for vaginal relapse of previously-irradiated endometrial cancer. We report our 10-year experience with management of vaginal recurrence using definitive intent re-irradiation brachytherapy with or without EBRT.

METHODS

A retrospective review was performed on 22 patients treated with definitive-intent re-irradiation brachytherapy ± EBRT for vaginal recurrence of endometrial cancer. The cumulative rectosigmoid and bladder D2cc (EQD2) were limited to <75 Gy and <90 Gy, respectively. Kaplan-Meier and Cox proportional hazards modeling were used to estimate survival. Severe (grade 3 or higher) radiation-related toxicities, defined according to CTCAE v4, were recorded.

RESULTS

Prior radiation therapy consisted of vaginal brachytherapy (54.5%), pelvic EBRT (22.7%), or combination pelvic EBRT and brachytherapy (22.7%). Median re-irradiation interval was 26.6 months. Salvage re-irradiation consisted of EBRT with brachytherapy in 50.0% and brachytherapy alone in 50.0%. Median HR-CTV D90 (EQD2) was 64.5 Gy (IQR: 49.6-75.8). Median cumulative D2cc for bladder, rectum, and sigmoid were 72.1 Gy (range: 30.3-81.8), 70.6 Gy (range: 32.0-80.5), and 52.7 Gy (range: 29.6-75.3), respectively. At a median follow-up of 27.6 months, 3-year local control, regional control, disease-free survival, and overall survival rates were 65.8%, 76.6%, 40.8%, and 68.1%, respectively. There were no grade ≥ 3 acute or late rectosigmoid or bladder toxicities.

CONCLUSION

Re-irradiation with 3D conformal brachytherapy for vaginal recurrence is feasible and safe as long as cumulative dose to surrounding normal organs is limited, and offers a chance to potentially salvage 40% of patients presenting with vaginal recurrence in the setting of prior pelvic radiation.

Image-based multichannel vaginal cylinder brachytherapy for the definitive treatment of gynecologic malignancies in the vagina

PURPOSE

Brachytherapy is integral to vaginal cancer treatment and is typically delivered using an intracavitary single-channel vaginal cylinder (SCVC) or an interstitial brachytherapy (ISBT) applicator. Multi-channel vaginal cylinder (MCVC) applicators allow for improved organ-at-risk (OAR) sparing compared to SCVC while maintaining target coverage. We present clinical outcomes of patients treated with image-based high dose-rate (HDR) brachytherapy using a MCVC.

METHODS AND MATERIALS

Sixty patients with vaginal cancer (27% primary vaginal and 73% recurrence from other primaries) were treated with combination external beam radiotherapy (EBRT) and image-based HDR brachytherapy utilizing a MCVC if residual disease thickness was 7 mm or less after EBRT. All pts received 3D image-based BT to a total equivalent dose of 70-80 Gy.

RESULTS

The median high-risk clinical target volume was 24.4 cm³ (interquartile range [IQR], 14.1), with a median dose to 90% of 77.2 Gy (IQR, 2.8). After a median follow-up of 45 months (range, 11-78), the 4-year local-regional control, distant control, DFS, and OS rates were 92.6%, 76.1%, 64.0%, and 67.2%, respectively. The 4-year LRC rates were similar between the primary vaginal (92%) and recurrent (93%) groups (p = 0.290). Pts with lymph node positive disease had a lower rate of distant control at 4 years (22.7% vs. 89.0%, p < 0.001). There were no Grade 3 or higher acute complications. The 4-year rate of late Grade 3 or higher toxicity was 2.7%.

CONCLUSIONS

Clinical outcomes of pts with primary and recurrent vaginal cancer treated definitively in a systematic manner with combination EBRT with image-guided HDR BT utilizing a MCVC applicator demonstrate high rates of local control and low rates of severe morbidity. The MCVC technique allows interstitial implantation to be avoided in select pts with ≤7 mm residual disease thickness following EBRT while maintaining excellent clinical outcomes with extended 4-year follow-up in this rare malignancy.

Long-Term Survivorship Following Stereotactic Radiosurgery Alone for Brain Metastases: Risk of Intracranial Failure and Implications for Surveillance and Counseling

BACKGROUND

Historically, survival for even highly select cohorts of brain metastasis patients selected for SRS alone is <2 yr; thus, limited literature on risks of recurrence exists beyond 2 yr.

OBJECTIVE

To investigate the possibility that for subsets of patients the risk of intracranial failure beyond 2 yr is less than the commonly quoted 50% to 60%, wherein less frequent screening may be appropriate.

METHODS

As a part of our institutional radiosurgery database, we identified 132 patients treated initially with stereotactic radiosurgery (SRS) alone (± pre-SRS surgical resection) with at least 2 yr of survival and follow-up from SRS. Primary study endpoints were rates of actuarial intracranial progression beyond 2 yr, calculated using the Kaplan-Meier and Cox regression methods.

RESULTS

The median follow-up from the first course of SRS was 3.5 yr. Significant predictors of intracranial failure beyond 2 yr included intracranial failure before 2 yr (52% vs 25%, P < .01) and total SRS tumor volume ≥5 cc (51% vs 25%, P < .01). On parsimonious multivariate analysis, failure before 2 yr (HR = 2.2, 95% CI: 1.2-4.3, P = .01) and total SRS tumor volume ≥5 cc (HR = 2.3, 95% CI: 1.2-4.3, P = .01) remained significant predictors of intracranial relapse beyond 2 yr.

CONCLUSION

Relapse rates beyond 2 yr following SRS alone for brain metastases are low in patients who do not suffer intracranial relapse within the first 2 yr and with low-volume brain metastases, supporting a practice of less frequent screening beyond 2 yr. For remaining patients, frequent (every 3-4 mo) screening remains prudent, as the risk of intracranial failure after 2 yr remains high.

Disparities Predict for Higher Rates of Cut-through Hysterectomies in Locally Advanced Cervical Cancer

OBJECTIVES

The treatment of choice for locally advanced cervical cancer is definitive chemoradiation (CRT). Hysterectomy is not indicated due to higher-rates of cut-through resections leaving gross disease behind, requiring additional therapy with increasing morbidity and no benefit in overall survival (OS). The objectives of this study were to determine factors associated with cut-through hysterectomies and evaluate OS outcomes.

MATERIALS AND METHODS

The National Cancer Database (NCDB) was queried for patients 18 years and older with clinical Federation of Gynecology and Obstetrics stage IB2 to IVA. All patients underwent upfront hysterectomy and had known margin status. Cut-through hysterectomy was classified as presence of microscopic or macroscopic disease at the margin.

RESULTS

A total of 11,638 patients were included; 993 (8.5%) had positive margins. In patients with positive margins, 560 (56.4%) received postoperative CRT and 148 (14.9%) underwent postoperative radiation. Five-year OS was worse for those with cut-through resections when compared with those with negative margins, 66.0% versus 86.7%, respectively (hazard ratios, 3.08; P<0.001). Under multiple logistic regression, African American race (odds ratio [OR], 1.45; P=0.001), older age (OR per year increase, 1.03; P<0.001), patients with government insurance (OR, 1.21; P=0.019), and those treated at community practices (OR, 1.31; P=0.001) were more likely to undergo cut-through hysterectomies.

CONCLUSIONS

A review of national patterns of care over the past decade confirms women with positive margins after hysterectomy for cervical cancer have significantly worse OS. Disparities in surgical results for women with cervical cancer exist. In response, further causality evaluation and corrective action are warranted to address these inequalities.

Stereotactic body radiation therapy for benign spine tumors: is dose de-escalation appropriate?

OBJECTIVE Akin to the nonoperative management of benign intracranial tumors, stereotactic body radiation therapy (SBRT) has emerged as a nonoperative treatment option for noninfiltrative primary spine tumors such as meningioma and schwannoma. The majority of initial series used higher doses of 16-24 Gy in 1-3 fractions. The authors hypothesized that lower doses (such as 12-13 Gy in 1 fraction) might provide an efficacy similar to that found with the dose de-escalation commonly used for intracranial radiosurgery to treat acoustic neuroma or meningioma and with a lower risk of toxicity. METHODS The authors identified 38 patients in a prospectively maintained institutional radiosurgery database who were treated with definitive SBRT for a total of 47 benign primary spine tumors between 2004 and 2016. SBRT consisted of 9-21 Gy in 1-3 fractions using the CyberKnife (n = 11 [23%]), Synergy S (n = 21 [45%]), or TrueBeam (n = 15 [32%]) radiosurgery platform. For a comparison of SBRT doses, patients were dichotomized into 1 of 2 groups (low-dose or high-dose SBRT) using a cutoff biologically effective dose (BED_10Gy) of 30 Gy. Tumor control was calculated from the date of SBRT to the last follow-up using Kaplan-Meier survival analysis, with comparisons between groups completed using a log-rank method. To account for potential indication bias, a propensity score analysis was completed based on the conditional probabilities of SBRT dose selection. Toxicity was graded using Common Terminology Criteria for Adverse Events version 4.0 with a focus on grade 3+ toxicity and the incidence of pain flare. RESULTS For the 38 patients, the most common histological findings were meningioma (15 patients), schwannoma (13 patients), and hemangioblastoma (7 patients). The median age at SBRT was 58 years (range 25-91 years). The 47 treated lesions were located in the cervical (n = 18), thoracic (n = 19), or lumbosacral (n = 10) spine. Five (11%) lesions were lost to follow-up after SBRT. The median follow-up duration for the remaining 42 lesions was 54 months (range 1.2-133 months). Six (16%) patients (with a total of 8 lesions) experienced pain flare after SBRT; no significant predictor of pain flare was identified. No grade 3+ acute- or late-onset complication was noted. The 5-year local control rate was 76% (95% CI 61%-91%). No significant difference in local control according to dose, fractionation, previous radiation, surgery, tumor histology, age, treatment platform, planning target volume, or spine level treated was found. The 5-year local control rates for low- and high-dose treatments were 73% (95% CI 53%-93%) and 83% (95% CI 61%-100%) (p = 0.52). In propensity score-adjusted multivariable analysis, no difference in local control was identified (HR 0.30, 95% CI 0.02-5.40; p = 0.41). CONCLUSIONS Long-term follow-up of patients treated with SBRT for benign spinal lesions revealed no significant difference between low-dose (BED_10Gy ≤ 30) and high-dose SBRT in local control, pain-flare rate, or long-term toxicity.

Utilizing clinical pathways and web-based conferences to improve quality of care in a large integrated network using breast cancer radiation therapy as the model

Background

Clinical pathways outline criteria for dose homogeneity and critical organ dosimetry. Based upon an internal audit showing suboptimal compliance with dosimetric parameters in whole breast irradiation (WBI), we conducted a mandatory web-based teaching conference for the network. This study reports the impact of this initiative on subsequent treatment plans.

Methods

Radiation treatment plans were collected for the 10 most recent patients receiving WBI at 16 institutions within the UPMC Hillman Cancer Center network. Subsequently, a web-based conference was conducted to educate staff physicians, physicists, and dosimetrists with goals for dose homogeneity and critical organ dosimetry. Six months post-conference, another 10 plans were collected from each site and compared to pre-conference plans for deviations from dosimetric criteria.

Results

Dose homogeneity significantly improved after the conference with breast V_105% decreasing from 15.6% to 11.2% (p = 0.004) and breast V_110% decreasing from 1.3% to 0.04% (p = 0.008). A higher percentage of cases were compliant with dosimetric criteria, with breast V_105% > 20% decreasing from 22.5% to 7.5% of cases (p = 0.0002) and breast V_110% > 0% decreasing from 13.8% to 4.4% of cases (p = 0.003).

Conclusions

Implementation of a web-based teaching conference helped improve adherence to clinical pathway dosimetric guidelines for WBI. In radiation oncology networks, this may be an effective model to ensure quality in routine practice and can be extrapolated to other disease sites.

Single-institutional outcomes of adjuvant brachytherapy for Stage I endometrial cancer-Are outcomes consistent with randomized studies?

PURPOSE

Vaginal brachytherapy (VBT) alone has been shown to be a viable adjuvant treatment strategy for most patients with Stage I endometrioid endometrial cancer. We sought to examine our institutional data following practice pattern changes resulting from the publications of GOG-99 and PORTEC-2.

METHODS AND MATERIALS

We retrospectively analyzed women who underwent adjuvant VBT after surgical staging for Stage 1 endometrioid endometrial cancer at our institution from 2007 to 2014.

RESULTS

We identified 297 women. Median time to last followup or death was 52.3 months (interquartile range: 32.3-72.3 months). By International Federation of Gynecology and Obstetrics 2009 staging, 162 patients (54.5%) had Stage IA and 128 (43.1%) had Stage IB disease. Ninety-nine (33.3%) patients had Grade 1, 153 (51.5%) had Grade 2, and 45 (15.2%) had Grade 3 disease. According to GOG-249 and PORTEC-2 criteria, 167 (56.2%) and 127 (42.7%) patients were with high-intermediate-risk disease. Two women had Stage IB Grade 3 disease. The most common high-dose-rate-VBT regimen was 2100 cGy/three fractions to a depth of 5 mm. Four (two acute and two late) (1.3%) Grade 3 genitourinary toxicities were reported: three episodes of vaginal dehiscence (after second course of VBT, 2 months after completion of VBT, and 1 year after completion of VBT) and one episode of radiation necrosis. Twenty-one (7%) women recurred: three recurred in the vagina, two recurred in the pelvic lymph nodes, and 16 recurred distantly.

CONCLUSIONS

Outcomes appear consistent with published randomized data in women with high-intermediate-risk endometrial cancer who are treated with brachytherapy alone. Recurrence and complication rates were minimal.

Challenges in the Analysis of Outcomes for Surgical Compared to Radiotherapy Treatment of Prostate Cancer

BACKGROUND/AIM

Prostate cancer can be treated with radical prostatectomy (RP), external-beam radiotherapy (EBRT), or brachytherapy (BT). These modalities have similar cancer-related outcomes. We used an innovative method to analyze the cost of such treatment.

MATERIALS AND METHODS

We queried our Institution's Insurance Division [University of Pittsburgh Medical Center (UPMC) Health Plan] beneficiaries from 2003-2008, who were diagnosed with prostate cancer and also queried the UPMC tumor registry for all patients with prostate cancer treated at our Institution. In a de-identified manner, data from the Health Plan and Tumor Registry were merged.

RESULTS

A total of 354 patients with non-metastatic disease with treatment initiated within 9 months of diagnosis were included (RP=236, EBRT=55, and BT=63). Radiotherapy-treated patients tended to be older, higher-risk, and have more comorbidities. Unadjusted median total health care expenditures during the first year after diagnosis were: RP: $16,743, EBRT: $47,256, and BT: $23,237 (p<0.0005). A propensity score-matched model comparing RP and EBRT demonstrated median total health care expenditures during year one: RP: $8,189, EBRT: $10,081; p=0.48. In a propensity-matched model comparing RP and BT, the median total health care expenditures during year one were: RP: $18,143, BT: $26,531; p=0.015 and per year during years 2 through 5 from diagnosis were: RP: $5,913, BT: $6,110; p=0.68.

CONCLUSION

This pilot study demonstrates the feasibility of combining healthcare costs from the payer's perspective with clinical data from a Tumor Registry within an IDFS and represents a novel approach to investigating the economic impact of cancer treatment.

Exceptional Eight-year Response to Stereotactic Radiosurgery Monotherapy for Multiple Brain Metastases

Breast cancer represents the second leading cause of brain metastases in women. Once diagnosed, brain metastases have been associated with a rapidly progressive and universally poor prognosis. Breast cancer patients, particularly those with advantageous disease characteristics, may achieve extended survival. This extended life expectancy highlights the importance of effective intracranial treatments that minimize treatment-related late toxicity.

Whole brain radiation therapy (WBRT) remains a standard of care palliative option; however, concerns remain regarding the late neurocognitive effects. Stereotactic radiosurgery (SRS) provides dose-escalated radiation therapy over a shortened course, maintaining equivalent survival and minimizing normal brain tissue exposure.

Herein, we present a breast cancer patient who demonstrated an exceptional response and remained functionally independent following 12 SRS courses targeting 14 unique brain metastases over eight years. The case illustrates the efficacy of SRS alone, as well as the comparable utility of multiple SRS treatment techniques (Gamma Knife (AB Elekta, Stockholm, Sweden), CyberKnife (Accuray, Sunnyvale, California), and TrueBeam (Varian Medical Systems, Palo Alto, California)).

Stereotactic body radiotherapy for locally-advanced unresectable pancreatic cancer-patterns of care and overall survival

BACKGROUND

Unresectable pancreatic cancer remains a challenging disease to treat. Stereotactic body radiotherapy (SBRT) allows for a higher biologically equivalent dose in an abbreviated course more convenient for patients and the integration of systemic therapy. We sought to investigate utilization trends and survival outcomes for patients treated with pancreatic SBRT versus conventionally fractionated radiotherapy (CFRT).

METHODS

We engaged the National Cancer Database (NCDB) from 1998-2012 and identified locally-advanced unresectable patients with histologically confirmed, non-metastatic, pancreatic adenocarcinoma who received radiotherapy. Patients who received CFRT (1.5-4.0 Gy per fraction to a dose of ≥45 Gy, n=11,879) were compared to those who received SBRT (6-15 Gy per fraction to a dose of ≥20 Gy, n=474).

RESULTS

Median follow-up was 11.0 months (18.4 months for survivors). SBRT utilization increased from 0.2% to 7.4% from 1998 to 2012 (P<0.05). On multivariable analysis, factors predictive for preferential utilization of SBRT over CFRT were later year of diagnosis, age ≥75 years, increased facility volume, and no chemotherapy in the initial treatment plan. Unadjusted median survival was 11.2 months for CFRT vs. 12.6 months for SBRT (P=0.002). Results were consistent in the propensity matched model. Variables predictive for improved survival on multivariable analysis were diagnosis after 2010, younger age, lower comorbidity score, tumor size <3 cm, nodal stage zero, and receipt of chemotherapy (P<0.05).

CONCLUSIONS

SBRT utilization has increased significantly and is associated with a small absolute improvement in overall survival (OS) compared to CFRT. The decreased treatment time, without apparent compromise in survival, makes SBRT an attractive option for patients with unresectable pancreatic cancer warranting further research.

Assessing Changes in the Activity Levels of Breast Cancer Patients During Radiation Therapy

BACKGROUND

Radiation therapy (RT) is often delivered after lumpectomy for women with breast cancer. A common perceived side effect of RT is fatigue, yet its exact effect on activity levels and sleep is unknown. In this study we analyzed the change in activity levels and sleep using an activity tracking device before, during, and after RT for women with early stage breast cancer and ductal carcinoma in situ who underwent adjuvant RT.

PATIENTS AND METHODS

After institutional review board approval, activity levels were quantified before, during, and after RT with measurements of steps, miles walked, calories burned, and sleep metrics in 10 women fitted with activity trackers. All data were uploaded and tabulated on a secure database. Multivariable linear regressions were used to evaluate changes in these variables over time during the RT course.

RESULTS

Median step count was 5047 per day (range, 2741-15,508) and distance traveled was 1.6 miles per day (range, 0.9-5.3). Step count, distance, and calories decreased by an average of 54 steps per day, 0.02 miles per day, and 3 calories per day (median calories 1822; range, 1461-2712) during RT, respectively. These changes were statistically significant (P < .001), but not clinically relevant. There was no significant change in sleep (average 6.8 hours per night; range, 5.5-8.3).

CONCLUSION

RT has a minimal effect on activity or sleep in women undergoing treatment for breast cancer. Activity levels varied greatly between patients in a population of women undergoing hypofractionated RT. Because increased activity levels correlate with improved outcomes, further studies evaluating attempts to increase physical activity during as well as after treatment with radiation are warranted.

Differences in urethral dosimetry between CT and MR imaging in multichannel vaginal cylinder brachytherapy

PURPOSE

In image-based brachytherapy (IBBT), the dosimetry of small structures may be particularly sensitive to changes in contouring between imaging modalities. We therefore sought to characterize differences in urethral dosimetry in vaginal brachytherapy based on contouring on MRI vs. CT.

METHODS AND MATERIALS

We retrospectively identified our most recent 15 patients treated with intracavitary brachytherapy for distal vaginal malignancies. On T2-weighted MRI, both the lumen and urethral wall were contoured. On CT, the urethral lumen alone was contoured, as the wall is indistinguishable from surrounding tissue. High-dose-rate (HDR) IBBT plans were generated for all patients.

RESULTS

Mean urethral volume was higher on MRI than CT at 3.7 cc vs. 1.1 cc (p < 0.0005). As a result, there were statistically significant increases on MRI in D_0.1cc and D_0.5cc, as well as EQD2 D_0.1cc and EQD2 D_0.5cc when applied to a full course of treatment (45 Gy EBRT + 25 Gy IBBT).

CONCLUSIONS

We have quantified the expected differences in urethral volume and dosimetry when contoured on MRI vs. CT. Inclusion of the urethral wall on MRI, with its average thickness of 2.2 mm, likely more accurately reflects the true organ at risk and results in an increase in reported dose compared to CT.

Brachytherapy boost for prostate cancer: Trends in care and survival outcomes

PURPOSE

Androgen suppression combined with elective nodal and dose-escalated radiation therapy recently demonstrated an improved biochemical failure-free survival in men who received external beam radiation therapy (EBRT) plus a brachytherapy boost (BB) compared with dose-escalated external beam radiotherapy (DE-EBRT). We sought to analyze the factors predictive for use of EBRT + BB as compared with DE-EBRT and report resulting survival outcomes on a national level using a hospital-based registry.

METHODS AND MATERIALS

We identified 113,719 men from the National Cancer Database from 2004 to 2013 with intermediate- or high-risk prostate cancer who were treated with EBRT + BB or DE-EBRT. We performed univariate and multivariate analyses of all available factors potentially predictive of receipt of treatment selection. Survival was evaluated in a multivariable model with propensity adjustment.

RESULTS

For intermediate-risk patients, utilization of BB decreased from 33.1% (n = 1742) in 2004 to 12.5% (n = 766) in 2013 and for high-risk patients, utilization dropped from 27.6% (n = 879) to 10.8% (n = 479). Numerous factors predictive for use of BB were identified. Cox proportional hazards analysis was performed-adjusting for age, Charlson-Deyo comorbidity score, T stage, prostate-specific antigen, Gleason score, and sociodemographic factors-and demonstrated BB use was associated with a hazard ratio of 0.71 (95% confidence interval, 0.67-0.75; p < 0.0005) and 0.73 (95% confidence interval, 0.68-0.78; p < 0.0005) for intermediate- and high-risk patients, respectively.

CONCLUSIONS

There has been a concerning decline in the utilization of BB for intermediate- and high-risk prostate cancer patients despite an association with improved on overall survival. Numerous factors predictive for use of BB have been identified.

Results of a Single Institution Experience with Dose-Escalated Chemoradiation for Locally Advanced Unresectable Non-Small Cell Lung Cancer

Background

We determined factors associated with morbidity and outcomes of a series of non-small cell lung cancer (NSCLC) patients treated with dose-escalated chemoradiotherapy at the University of Pittsburgh Lung Cancer Program.

Methods and materials

The records of 170 stage III NSCLC patients treated with definitive intent were retrospectively reviewed. All patients received four-dimensional CT simulation scan and had respiratory gating if tumor movement exceeded 5 mm. Overall survival (OS), locoregional control (LRC), and freedom from distant metastasis (FFDM) were calculated using log-rank and Cox regression analysis.

Results

For the present series of patients, median follow-up was 36.6 months, median survival 27.4 months, and the 2- and 4-year OS was 56.0 and 30.7%, respectively. The 4-year LRC and FFDM were 43.9 and 40.7%, respectively. No benefit was associated with irradiation doses above 66 Gy in OS (p = 0.586), LRC (p = 0.440), or FFDM (p = 0.230). On univariate analysis, variables associated with worse survival included: clinical stage IIIB (p = 0.037), planning target volume (PTV) over 450 cc (p < 0.001), heart V₃₀ over 40% (p = −0.048), and esophageal mean dose over 20% (p = 0.024), V₅ (p = −0.015), and V₆₀ (p = −0.011). On multivariable analysis, PTV above 450 cc (52.2 vs. 25.3 months, p < 0.001) and esophageal V₆₀ >20% (43.8 vs. 21.3 months, p = −0.01) were associated with lower survival. Grade 2 or higher acute lung toxicity and esophagitis were detected in 9.5 and 59.7%, respectively of patients. Grade 2 or higher acute lung toxicity was reduced if lung V₅ was ≤65 (7.4 vs. 23.8%, p = 0.03). Grade 2 or higher acute esophagitis was reduced if V₆₀ ≤ 20% (62 vs. 81.3%, p = 0.018). The use of intensity-modulated radiation therapy was more frequent in stage IIIB compared to stage IIIA patients (56.5 vs. 39.5%, p = 0.048) and was associated with a higher lung V₅ and V₁₀.

Conclusion

The outcomes of a program of dose-escalated chemoradiotherapy for unresectable stage IIIA and IIIB NSCLC patients were consistent with other studies and showed no benefit to radiation doses above 66 Gy. Furthermore, maintaining low esophageal V₆₀ and lung V₅ were associated with lower morbidity and mortality.

Secretion from bacterial versus mammalian cells yields a recombinant scFv with variable folding properties

Escherichia coli (E. coli) is the most commonly used organism for expressing antibody fragments such as single chain antibody Fvs (scFvs). Previously, we have utilized E. coli to express well-folded scFvs for characterization and engineering purposes with the goal of using these engineered proteins as building blocks for generating IgG-like bispecific antibodies (BsAbs). In the study, described here, we observed a significant difference in the secondary structure of an scFv produced in E. coli and the same scFv expressed and secreted from chinese hamster ovary (CHO) cells as part of a BsAb. We devised a proteolytic procedure to separate the CHO-derived scFv from its antibody-fusion partner and compared its properties with those of the E. coli-derived scFv. In comparison to the CHO-derived scFv, the E. coli-derived scFv was found trapped in a misfolded, but monomeric state that was stable for months at 4 °C. The misfolded state bound antigen in a heterogeneous fashion that included non-specific binding, which made functional characterization challenging. This odd incidence of obtaining a misfolded scFv from bacteria suggests careful characterization of the folded properties of bacterially expressed scFvs is warranted if anomalous issues with antigen-binding or non-specificity occur during an engineering campaign. Additionally, our proteolytic methodology for obtaining significant levels of intact scFvs from highly expressed IgG-like antibody proteins serves as a robust method for producing scFvs in CHO without the use of designed cleavage motifs.

A stable IgG-like bispecific antibody targeting the epidermal growth factor receptor and the type I insulin-like growth factor receptor demonstrates superior anti-tumor activity

The epidermal growth factor receptor (EGFR) and the type I insulin-like growth factor receptor (IGF-1R) are two cell surface receptor tyrosine kinases known to cooperate to promote tumor progression and drug resistance. Combined blockade of EGFR and IGF-1R has shown improved anti-tumor activity in preclinical models. Here, we report the characterization of a stable IgG-like bispecific antibody (BsAb) dual-targeting EGFR and IGF-1R that was developed for cancer therapy. The BsAb molecule (EI-04), constructed with a stability-engineered single chain variable fragment (scFv) against IGF-1R attached to the carboxyl-terminus of an IgG against EGFR, displays favorable biophysical properties for biopharmaceutical development. Biochemically, EI-04 bound to human EGFR and IGF-1R with sub nanomolar affinity, co-engaged the two receptors simultaneously, and blocked the binding of their respective ligands with similar potency compared to the parental monoclonal antibodies (mAbs). In tumor cells, EI-04 effectively inhibited EGFR and IGF-1R phosphorylation, and concurrently blocked downstream AKT and ERK activation, resulting in greater inhibition of tumor cell growth and cell cycle progression than the single mAbs. EI-04, likely due to its tetravalent bispecific format, exhibited high avidity binding to BxPC3 tumor cells co-expressing EGFR and IGF-1R, and consequently improved potency at inhibiting IGF-driven cell growth over the mAb combination. Importantly, EI-04 demonstrated enhanced in vivo anti-tumor efficacy over the parental mAbs in two xenograft models, and even over the mAb combination in the BxPC3 model. Our data support the clinical investigation of EI-04 as a superior cancer therapeutic in treating EGFR and IGF-1R pathway responsive tumors.

Stable IgG-like bispecific antibodies directed toward the type I insulin-like growth factor receptor demonstrate enhanced ligand blockade and anti-tumor activity

Bispecific antibodies (BsAbs) target multiple epitopes on the same molecular target or different targets. Although interest in BsAbs has persisted for decades, production of stable and active BsAbs has hindered their clinical evaluation. Here, we describe the production and characterization of tetravalent IgG-like BsAbs that combine the activities of allosteric and competitive inhibitors of the type-I insulin-like growth factor receptor (IGF-1R). The BsAbs, which were engineered for thermal stability, express well, demonstrate favorable biophysical properties, and recognize both epitopes on IGF-1R. Only one BsAb with a unique geometry, denoted BIIB4-5scFv, was capable of engaging all four of its binding arms simultaneously. All the BsAbs (especially BIIB4-5scFv) demonstrated enhanced ligand blocking over the single monoclonal antibodies (mAbs), particularly at high ligand concentrations. The pharmacokinetic profiles of two IgG-like BsAbs were tested in nude mice and shown to be comparable with that of the parental mAbs. The BsAbs, especially BIIB4-5scFv, demonstrated an improved ability to reduce the growth of multiple tumor cell lines and to inhibit ligand-induced IGF-1R signaling in tumor cells over the parental mAbs. BIIB4-5scFv also led to superior tumor growth inhibition over its parental mAbs in vivo. In summary, BsAbs that bridge multiple inhibitory mechanisms against a single target may generally represent a more effective strategy for intervention in oncology or other indications compared with traditional mAb therapy.

Combination of two insulin-like growth factor-I receptor inhibitory antibodies targeting distinct epitopes leads to an enhanced antitumor response

The insulin-like growth factor-I receptor (IGF-IR) is a cell surface receptor tyrosine kinase that mediates cell survival signaling and supports tumor progression in multiple tumor types. We identified a spectrum of inhibitory IGF-IR antibodies with diverse binding epitopes and ligand-blocking properties. By binding distinct inhibitory epitopes, two of these antibodies, BIIB4 and BIIB5, block both IGF-I and IGF-II binding to IGF-IR using competitive and allosteric mechanisms, respectively. Here, we explored the inhibitory effects of combining BIIB4 and BIIB5. In biochemical assays, the combination of BIIB4 and BIIB5 improved both the potency and extent of IGF-I and IGF-II blockade compared with either antibody alone. In tumor cells, the combination of BIIB4 and BIIB5 accelerated IGF-IR downregulation and more efficiently inhibited IGF-IR activation as well as downstream signaling, particularly AKT phosphorylation. In several carcinoma cell lines, the antibody combination more effectively inhibited ligand-driven cell growth than either BIIB4 or BIIB5 alone. Notably, the enhanced tumor growth-inhibitory activity of the BIIB4 and BIIB5 combination was much more pronounced at high ligand concentrations, where the individual antibodies exhibited substantially reduced activity. Compared with single antibodies, the BIIB4 and BIIB5 combination also significantly further enhanced the antitumor activity of the epidermal growth factor receptor inhibitor erlotinib and the mTOR inhibitor rapamycin. Moreover, in osteosarcoma and hepatocellular carcinoma xenograft models, the BIIB4 and BIIB5 combination significantly reduced tumor growth to a greater degree than each single antibody. Taken together, our results suggest that targeting multiple distinct inhibitory epitopes on IGF-IR may be a more effective strategy of affecting the IGF-IR pathway in cancer.