Stereotactic body radiotherapy plus rucosopasem in locally advanced or borderline resectable pancreatic cancer: GRECO-2 phase II study design

Ablative doses of stereotactic body radiotherapy (SBRT) may improve pancreatic cancer outcomes but may carry greater potential for gastrointestinal toxicity. Rucosopasem, an investigational selective dismutase mimetic that converts superoxide to hydrogen peroxide, can potentially increase tumor control of SBRT without compromising safety. GRECO-2 is a phase II, multicenter, randomized, double-blind, placebo-controlled trial of rucosopasem in combination with SBRT in locally advanced or borderline resectable pancreatic cancer. Patients will be randomized to rucosopasem 100 mg or placebo via intravenous infusion over 15 min, before each SBRT fraction (5 × 10 Gy). The primary end point is overall survival. Secondary end points include progression-free survival, locoregional control, time to metastasis, surgical resection rate, best overall response, in-field local response and acute and long-term toxicity.

Stereotactic body radiotherapy with or without selective dismutase mimetic in pancreatic adenocarcinoma: an adaptive, randomised, double-blind, placebo-controlled, phase 1b/2 trial

BACKGROUND

Stereotactic body radiotherapy (SBRT) has the potential to ablate localised pancreatic ductal adenocarcinoma. Selective dismutase mimetics sensitise tumours while reducing normal tissue toxicity. This trial was designed to establish the efficacy and toxicity afforded by the selective dismutase mimetic avasopasem manganese when combined with ablative SBRT for localised pancreatic ductal adenocarcinoma.

METHODS

In this adaptive, randomised, double-blind, placebo-controlled, phase 1b/2 trial, patients aged 18 years or older with borderline resectable or locally advanced pancreatic cancer who had received at least 3 months of chemotherapy and had an Eastern Cooperative Oncology Group performance status of 0-2 were enrolled at six academic sites in the USA. Eligible patients were randomly assigned (1:1), with block randomisation (block sizes of 6-12) with a maximum of 24 patients per group, to receive daily avasopasem (90 mg) or placebo intravenously directly before (ie, within 180 min) SBRT (50, 55, or 60 Gy in five fractions, adaptively assigned in real time by Bayesian estimates of 90-day safety and efficacy). Patients and physicians were masked to treatment group allocation, but not to SBRT dose. The primary objective was to find the optimal dose of SBRT with avasopasem or placebo as determined by the late onset EffTox method. All analyses were done on an intention-to-treat basis. This study is registered with ClinicalTrials.gov, NCT03340974, and is complete.

FINDINGS

Between Jan 25, 2018, and April 29, 2020, 47 patients were screened, of whom 42 were enrolled (median age was 71 years [IQR 63-75], 23 [55%] were male, 19 [45%] were female, 37 [88%] were White, three [7%] were Black, and one [2%] each were unknown or other races) and randomly assigned to avasopasem (n=24) or placebo (n=18); the placebo group was terminated early after failing to meet prespecified efficacy parameters. At data cutoff (June 28, 2021), the avasopasem group satisfied boundaries for both efficacy and toxicity. Late onset EffTox efficacy response was observed in 16 (89%) of 18 patients at 50 Gy and six (100%) of six patients at 55 Gy in the avasopasem group, and was observed in three (50%) of six patients at 50 Gy and nine (75%) of 12 patients at 55 Gy in the placebo group, and the Bayesian model recommended 50 Gy or 55 Gy in five fractions with avasopasem for further study. Serious adverse events of any cause were reported in three (17%) of 18 patients in the placebo group and six (25%) of 24 in the avasopasem group. In the placebo group, grade 3 adverse events within 90 days of SBRT were abdominal pain, acute cholangitis, pyrexia, increased blood lactic acid, and increased lipase (one [6%] each); no grade 4 events occurred. In the avasopasem group, grade 3-4 adverse events within 90 days of SBRT were acute kidney injury, increased blood alkaline phosphatase, haematoma, colitis, gastric obstruction, lung infection, abdominal abscess, post-surgical atrial fibrillation, and pneumonia leading to respiratory failure (one [4%] each).There were no treatment-related deaths but one late death in the avasopasem group due to sepsis in the setting of duodenal obstruction after off-study treatment was reported as potentially related to SBRT.

INTERPRETATION

SBRT that uses 50 or 55 Gy in five fractions can be considered for patients with localised pancreatic ductal adenocarcinoma. The addition of avasopasem might further enhance disease outcomes. A larger phase 2 trial (GRECO-2, NCT04698915) is underway to validate these results.

FUNDING

Galera Therapeutics.

Radioembolization with Yttrium-90 Glass Microspheres as a First-Line Treatment for Unresectable Intrahepatic Cholangiocarcinoma-A Prospective Feasibility Study

PURPOSE

To evaluate the safety and effectiveness of yttrium-90 (90Y) radioembolization as first-line treatment for unresectable intrahepatic cholangiocarcinoma (ICC).

MATERIALS AND METHODS

This prospective study enrolled patients who had never received chemotherapy, liver embolization, and radiation therapy. The tumors were solitary in 16 patients, multiple in 8 patients, unilobar in 14 patients, and bilobar in 10 patients. Patients underwent transarterial radioembolization with 90Y-labeled glass microspheres. The primary end point was hepatic progression-free survival (HPFS). Secondary end points were overall survival (OS), tumor response, and toxicity.

RESULTS

Twenty-four patients (age, 72.3 years ± 9.3; 12 women) were included in the study. The median delivered radiation dose was 135.5 Gy (interquartile range, 77.6 Gy). The median HPFS was 5.5 months (95% CI, 3.9-7.0 months). Analysis failed to identify any prognostic factor associated with HPFS. Imaging response at 3 months showed 56% disease control, and the best radiographic response was 71% disease control. The median OS from the radioembolization treatment was 19.4 months (95% CI, 5.0-33.7). Patients with solitary ICC had significantly longer median OS than patients with multifocal ICC: 25.9 months (95% CI, 20.8-31.0 months) versus 10.7 months (95% CI, 8.0-13.4 months) (P = .02). Patients with progression on the 3-month imaging follow-up had significantly shorter median OS than patients who had stable disease at 3 months: 10.7 months (95% CI, 0.7-20.7 months) versus 37.3 months (95% CI, 16.5-58.1 months) (P = .003). Two (8%) Grade 3 toxicities were reported.

CONCLUSIONS

First-line treatment of ICC with radioembolization showed promising OS and minimal toxicity, especially in patients with solitary tumor. Radioembolization may be considered as a first-line treatment option for unresectable ICC.

Induction Fluorouracil-Based Chemotherapy and PET-Adapted Consolidation Chemoradiation with Esophagectomy for High-Risk Gastroesophageal Adenocarcinoma

Background: Neoadjuvant chemoradiation with esophagectomy is standard management for locally advanced esophageal adenocarcinoma. Induction chemotherapy with a tailored approach to chemoradiation based on metabolic response to therapy on PET was explored as an alternative strategy in the CALGB 80803 trial. We sought to describe real-world institutional experience implementing this approach outside of a clinical trial. Methods: Patients who were treated with induction fluorouracil-leucovorin-oxaliplatin (FOLFOX) or fluorouracil-leucovorin-oxaliplatin-docetaxel (FLOT) with tailored chemoradiation based on PET response and subsequent esophagectomy were identified from a prospectively maintained database. Primary outcomes were pathologic complete response (pCR) and overall survival (OS) following completion of all therapy. Results: There were 35 patients who completed induction chemotherapy, chemoradiation, and esophagectomy. Thirty-three completed restaging PET following induction chemotherapy with metabolic response seen in 76% (n = 25/33). The pCR rate was 31% (n = 11/35) and the ypN0 rate was 71% (n = 25/35). Among the patients who demonstrated metabolic response to induction FOLFOX/FLOT and subsequently continued fluorouracil-based chemoradiation, the pCR rate was 39% (n = 9/23). The rate of pathologically negative lymph nodes in this group was high (n = 19/23, 83%) with 100% R0 resection rate (n = 23/23). With the median follow-up of 43 months, the median OS was not reached for this group and was significantly longer than the OS for the remainder of the cohort (p = 0.027, p = 0.046 adjusted for clinical stage). Conclusions: Induction FOLFOX/FLOT chemotherapy with evaluation of sensitivity via metabolic response and tailored chemoradiation seems to lead to high pCR and ypN0 rates in high-risk patients with adenocarcinoma of the esophagus and GE junction. This approach in clinical practice seems to recapitulate encouraging results in clinical trials.

Neoadjuvant chemotherapy and stereotactic body radiation therapy for borderline resectable pancreas adenocarcinoma: influence of vascular margin status and type of chemotherapy

BACKGROUND

The influence of chemotherapy type and vascular margin status after sequential chemotherapy and stereotactic body radiation therapy (SBRT) for borderline resectable pancreatic cancer (BRPC) is unknown.

METHODS

A retrospective review was performed on BRPC patients treated with chemotherapy and 5-fraction SBRT from 2009 to 2021. Surgical outcomes and SBRT-related toxicity were reported. Clinical outcomes were estimated by Kaplan-Meier with log rank comparisons.

RESULTS

A total of 303 patients received neoadjuvant chemotherapy and SBRT to a median dose of 40 Gy prescribed to the tumor-vessel interface and median dose of 32.4 Gyto 95% of the gross tumor volume. One hundred and sixty-nine patients (56%) were resected and benefited from improved median OS (41.1 vs 15.5 months, P < 0.001). Close/positive vascular margins were not associated with worse OS or FFLRF. Type of neoadjuvant chemotherapy did not influence OS for resected patients, but FOLFIRINOX was associated with improved median OS in unresected patients (18.2 vs 13.1 months, P = 0.001).

CONCLUSION

For BRPC, the effect of a positive or close vascular margin may be mitigated by neoadjuvant therapy. Shorter duration neoadjuvant chemotherapy as well as the optimal biological effective dose of radiotherapy should be prospectively explored.

FOLFIRINOX or Gemcitabine-based Chemotherapy for Borderline Resectable and Locally Advanced Pancreatic Cancer: A Multi-institutional, Patient-Level, Meta-analysis and Systematic Review

BACKGROUND

Pancreatic cancer often presents as locally advanced (LAPC) or borderline resectable (BRPC). Neoadjuvant systemic therapy is recommended as initial treatment. It is currently unclear what chemotherapy should be preferred for patients with BRPC or LAPC.

METHODS

We performed a systematic review and multi-institutional meta-analysis of patient-level data regarding the use of initial systemic therapy for BRPC and LAPC. Outcomes were reported separately for tumor entity and by chemotherapy regimen including FOLFIRINOX (FIO) or gemcitabine-based.

RESULTS

A total of 23 studies comprising 2930 patients were analyzed for overall survival (OS) calculated from the beginning of systemic treatment. OS for patients with BRPC was 22.0 months with FIO, 16.9 months with gemcitabine/nab-paclitaxel (Gem/nab), 21.6 months with gemcitabine/cisplatin or oxaliplatin or docetaxel or capecitabine (GemX), and 10 months with gemcitabine monotherapy (Gem-mono) (p < 0.0001). In patients with LAPC, OS also was higher with FIO (17.1 months) compared with Gem/nab (12.5 months), GemX (12.3 months), and Gem-mono (9.4 months; p < 0.0001). This difference was driven by the patients who did not undergo surgery, where FIO was superior to other regimens. The resection rates for patients with BRPC were 0.55 for gemcitabine-based chemotherapy and 0.53 with FIO. In patients with LAPC, resection rates were 0.19 with Gemcitabine and 0.28 with FIO. In resected patients, OS for patients with BRPC was 32.9 months with FIO and not different compared to Gem/nab, (28.6 months, p = 0.285), GemX (38.8 months, p = 0.1), or Gem-mono (23.1 months, p = 0.083). A similar trend was observed in resected patients converted from LAPC.

CONCLUSIONS

In patients with BRPC or LAPC, primary treatment with FOLFIRINOX compared with Gemcitabine-based chemotherapy appears to provide a survival benefit for patients that are ultimately unresectable. For patients that undergo surgical resection, outcomes are similar between GEM+ and FOLFIRINOX when delivered in the neoadjuvant setting.

Greco-2: A randomized, phase 2 study of stereotactic body radiation therapy (SBRT) in combination with rucosopasem (GC4711) in the treatment of locally advanced or borderline resectable nonmetastatic pancreatic cancer

TPS766

Background: While treatment of pancreatic cancer has advanced, survival rates remain low. Stereotactic body radiotherapy (SBRT; high dose per fraction radiation) may exhibit improved clinical outcomes in locally advanced pancreatic cancer but carries potential gastrointestinal toxicity risks. Rucosopasem (GC4711) is one of a class of investigational selective dismutase mimetics that rapidly and specifically converts superoxide to hydrogen peroxide. Studies have shown that normal cells tolerate hydrogen peroxide fluxes better than cancer cells. As radiation response modifiers, dismutase mimetics have the potential to increase tumor control of SBRT without compromising radiation safety. In a pilot phase 1/2 trial in patients with pancreatic cancer, avasopasem, a dismutase mimetic related to rucosopasem, nearly doubled median overall survival in patients receiving SBRT vs placebo plus SBRT. Improvements versus placebo were also observed in local tumor control, time to metastases, and progression-free survival. Altogether, these data support the hypothesis that rucosopasem may improve survival and the benefit-risk ratio of SBRT by improving efficacy without increasing gastrointestinal toxicity. Methods: GRECO-2 is a phase 2, multicenter, randomized, double-blind, placebo-controlled study (NCT04698915) to determine the effect of adding rucosopasem to SBRT on overall survival in patients with borderline resectable or locally advanced, unresectable nonmetastatic pancreatic cancer following initial chemotherapy with a FOLFIRINOX-based regimen or a gemcitabine doublet. Approximately 160 patients will be randomized (approximately 35 sites) to receive rucosopasem 100 mg or placebo via IV infusion over 15 minutes, prior to each SBRT fraction (5 x 10 Gy). Patients judged to be resectable will undergo surgical exploration within 8 weeks after SBRT. The primary endpoint is overall survival. Secondary endpoints include progression-free survival, locoregional control, time to metastasis, surgical resection rate, RO resection rate, best overall response, in-field local response, and safety (acute and late toxicities). Exploratory endpoints include PRO-CTCAE and CA19-9 normalization. This trial (NCT04698915) is now enrolling. Clinical trial information: NCT04698915 .

Multi-Institutional Outcomes of Patients Aged 75 years and Older With Pancreatic Ductal Adenocarcinoma Treated With 5-Fraction Ablative Stereotactic Magnetic Resonance Image-Guided Adaptive Radiation Therapy (A-SMART)

PURPOSE

Treatment options for pancreatic ductal adenocarcinoma (PDAC) are commonly limited for patients with advanced age due to medical comorbidities and/or poor performance status. These patients may not be candidates for more aggressive chemotherapy regimens and/or surgical resection leaving few, if any, other effective treatments. Ablative stereotactic MRI-guided adaptive radiation therapy (A-SMART) is both efficacious and safe for PDAC and can achieve excellent long-term local control, however, the appropriateness of A-SMART for elderly patients with inoperable PDAC is not well understood.

METHODS

A retrospective analysis was performed of inoperable non-metastatic PDAC patients aged 75 years or older treated on the MRIdian Linac at 2 institutions. Clinical outcomes of interest included overall survival (OS), progression-free survival (PFS), distant metastasis-free survival (DMFS), and locoregional (LRC). Toxicity was graded according to Common Terminology Criteria for Adverse Events (CTCAE, v5).

RESULTS

A total of 49 patients were evaluated with a median age of 81 years (range, 75-91) and a median follow-up of 14 months from diagnosis. PDAC was classified as locally advanced (46.9%), borderline resectable (36.7%), or medically inoperable (16.3%). Neoadjuvant chemotherapy was delivered to 84% of patients and all received A-SMART to a median 50 Gy (range, 40-50 Gy) in 5 fractions. 1 Year LRC, PFS, and OS were 88.9%, 53.8%, and 78.9%, respectively. Nine patients (18%) had resection after A-SMART and benefited from PFS improvement (26 vs 6 months, P = .01). ECOG PS <2 was the only predictor of improved OS on multivariate analysis. Acute and late grade 3 + toxicity rates were 8.2% and 4.1%, respectively.

CONCLUSIONS

A-SMART is associated with encouraging LRC and OS in elderly patients with initially inoperable PDAC. This novel non-invasive treatment strategy appears to be well-tolerated in patients with advanced age and should be considered in this population that has limited treatment options.

A Practical Workflow for Magnetic Resonance-Guided Stereotactic Body Radiation Therapy to the Pancreas

The increased adoption of stereotactic body radiation therapy has allowed for delivery of higher doses, potentially associated with better outcomes but at the risk of higher toxicity. The intimate association of radiosensitive organs at risk (eg, stomach, duodenum, bowel) has historically limited the delivery of ablative doses to the pancreas. The advent of magnetic resonance-guided radiation therapy with improved soft-tissue contrast allows for gated delivery without an internal target volume and online adaptive replanning to maximize the therapeutic ratio. Patient selection requires additional resources, including increased patient on-table time, physician time, and physics support. Within our center's workflow, integrating an educational video at consultation as well as optimizing biofeedback mechanisms have significantly improved the experience for our patients.

Ablative 5-Fraction Stereotactic MRI-Guided Adaptive Radiotherapy for Oligometastatic Pancreatic Adenocarcinoma

INTRODUCTION

Metastatic pancreatic ductal adenocarcinoma (PDAC) carries a poor prognosis and significant morbidity from local tumor progression. We investigated outcomes among oligometastatic PDAC patients treated with stereotactic magnetic resonance image-guided ablative radiotherapy (SMART) to primary disease.

METHODS

We performed a retrospective multi-institutional analysis of oligometastatic PDAC at diagnosis or with metachronous oligoprogression during induction chemotherapy treated with primary tumor SMART. Outcomes of interest included overall survival (OS), progression-free survival (PFS), freedom from locoregional failure (FFLRF), and freedom from distant failure (FFDF). Acute and late toxicity were reported and in exploratory analyses patients were stratified by the number of metastases, SMART indication, and addition of metastasis-directed therapy.

RESULTS

From 2019 to 2021, 22 patients with oligometastatic PDAC (range: 1-6 metastases) received SMART to the primary tumor with a median follow-up of 11.2 months from SMART. Nineteen patients had de novo synchronous metastatic disease and three had metachronous oligoprogression. Metastasis location most commonly was liver only (40.9%), multiple organs (27.3%), lungs only (13.6%), or abdominal/pelvic nodes (13.6%). All patients received either FOLFIRINOX (64%) or gemcitabine/nab-paclitaxel (36%) followed by SMART (median 50 Gy, 5 fractions) for local control (77%), pain control (14%), or local progression (9%). Additionally, 41% of patients received other metastasis-directed treatments. The median OS from diagnosis and SMART was 23.9 months and 11.6 months, respectively. Calculated from SMART, the median PFS was 2.4 months with 91% of patients having distant progression, and 1-year local control was 68. Two patients (9%) experienced grade 3 toxicities, gastric outlet obstruction, and gastrointestinal bleed without grade 4 or 5 toxicity.

CONCLUSION

There was minimal morbidity of local disease progression after SMART in this cohort of oligometastatic PDAC. As systemic therapy options improve, additional strategies to identify patients who may derive benefits from local consolidation or metastasis-directed therapy are needed.

Developing a Dedicated Leadership Curriculum for Radiation Oncology Residents

The increasing complexity of healthcare emphasizes the need for continued physician leadership and leadership training. This study aims to determine baseline attitudes toward the perceptions and utility of a leadership development curriculum (LDC) for radiation oncology (RO) residents. A novel longitudinal LDC was implemented for RO residents at our institution from 2018 to 2019. Prior to the curriculum, current and past residents in our institution's RO residency program were surveyed on their attitudes towards leadership in healthcare, emotional intelligence competencies, and leadership training interests. After the completion of the LDC, a post-curriculum survey was forwarded to current residents. The response rate was 84% (21 of 24) for the baseline survey and 90% (9 of 10) for the post-curriculum survey. Having a leadership training curriculum during residency was rated as extremely useful, with top training interests involving leading clinical teams, effective communication strategies, and conflict management. After the LDC, the residents reported high satisfaction with the curriculum and utilization of leadership training into their daily work. Our LDC demonstrates significant potential to engage trainees and improve their leadership skills at the graduate medical education level.

The effect of histologic grade on neoadjuvant treatment outcomes in esophageal cancer

BACKGROUND AND OBJECTIVES

The gold standard for locoregional esophageal cancer (LEC) treatment includes preoperative chemoradiation and surgical resection, with possible perioperative or adjuvant systemic therapy. With few data associating histologic grade and prognosis in LEC patients receiving neoadjuvant chemoradiation followed by resection, we seek to evaluate this association.

METHODS

Our institutional esophagectomy database between 1999 and 2019 was queried, selecting esophageal adenocarcinoma patients who completed neoadjuvant therapy (NAT), followed by esophagectomy. Propensity-score matching of low- and high-histologic grade groups was performed to assess survival metrics using initial clinical grade (cG) and final pathologic grade (pG). We performed a multivariable logistic regression to study predictors of pathologic complete response as a secondary objective.

RESULTS

A total of 518 patients met the inclusion criteria. Kaplan-Meier analysis of the matched dataset showed no difference in initial or 5-year recurrence-free survival or overall survival (OS) between cG1 and cG2 versus cG3 based on original grade. When matched according to pG, cG1-2 had improved median survival parameters compared to cG3, with 5-year OS for cG1-2 of 45% versus 27% (p = 0.001). Higher pG, pathologic N stage, and poor response to NAT are predictors of poor survival.

CONCLUSION

Patients with post-NAT pG1-2 demonstrated improved survival. Integrating histologic grade into postneoadjuvant staging may be warranted.

GRECO-2: A randomized, phase 2 study of stereotactic body radiation therapy (SBRT) in combination with rucosopasem (GC4711) in the treatment of locally advanced or borderline resectable nonmetastatic pancreatic cancer

TPS4184

Background: While treatment of pancreatic cancer has advanced, survival rates remain low. Stereotactic body radiotherapy (SBRT; high dose per fraction radiation) may exhibit improved clinical outcomes in locally advanced pancreatic cancer but carries potential gastrointestinal toxicity risks (Zhong 2017). Rucosopasem (GC4711) is one of a class of investigational selective dismutase mimetics that rapidly and specifically converts superoxide to hydrogen peroxide (Riley 2006). Studies have shown that normal cells tolerate hydrogen peroxide fluxes better than cancer cells (Doskey 2016). As radiation response modifiers, dismutase mimetics have the potential to increase tumor control of SBRT without compromising radiation safety (El-Mahdy 2020, Sishc 2021). In a pilot phase 1/2 trial in patients with pancreatic cancer, avasopasem, a dismutase mimetic related to rucosopasem, nearly doubled median overall survival in patients receiving SBRT vs placebo plus SBRT. Improvements versus placebo were also observed in local tumor control, time to metastases, and progression-free survival. Altogether, these data support the hypothesis that rucosopasem may improve survival and the benefit-risk ratio of SBRT by improving efficacy without increasing gastrointestinal toxicity. Materials/Methods: GRECO-2 is a phase 2, multicenter, randomized, double-blind, placebo-controlled study (NCT04698915) to determine the effect of adding rucosopasem to SBRT on overall survival in patients with borderline resectable or locally advanced, unresectable nonmetastatic pancreatic cancer following initial chemotherapy with a FOLFIRINOX-based regimen or a gemcitabine doublet. Approximately 160 patients will be randomized (approximately 35 sites) to receive rucosopasem 100 mg or placebo via IV infusion over 15 minutes, prior to each SBRT fraction (5 x 10 Gy). Patients judged to be resectable will undergo surgical exploration within 8 weeks after SBRT. The primary endpoint is overall survival. Secondary endpoints include progression-free survival, locoregional control, time to metastasis, surgical resection rate, RO resection rate, best overall response, in-field local response, and safety (acute and late toxicities). Exploratory endpoints include PRO-CTCAE and CA19-9 normalization. This trial is now enrolling. Clinical trial information: NCT04698915.

Evaluation of Tumor DNA Sequencing Results in Patients with Gastric and Gastroesophageal Junction Adenocarcinoma Stratified by TP53 Mutation Status

Background

Gastric cancer (GC) and gastroesophageal junction adenocarcinomas (GEJ) are molecularly diverse. TP53 is the most frequently altered gene with approximately 50% of patients harboring mutations. This qualitative study describes the distinct genomic alterations in GCs and GEJs stratified by TP53 mutation status.

Patients and Methods

Tumor DNA sequencing results of 324 genes from 3741 patients with GC and GEJ were obtained from Foundation Medicine. Association between gene mutation frequency and TP53 mutation status was examined using Fisher’s exact test. Functional gene groupings representing molecular pathways suggested to be differentially mutated in TP53 wild-type (TP53WT) and TP53 mutant (TP53MUT) tumors were identified. The association of the frequency of tumors containing a gene mutation in the molecular pathways of interest and TP53 mutation status was assessed using Fisher’s exact test with a P-value of &lt;.01 deemed statistically significant for all analyses.

Results

TP53 mutations were noted in 61.6% of 2946 GCs and 81.4% of 795 GEJs (P &lt; .001). Forty-nine genes had statistically different mutation frequencies in TP53WT vs. TP53MUT patients. TP53WT tumors more likely had mutations related to DNA mismatch repair, homologous recombination repair, DNA and histone methylation, Wnt/B-catenin, PI3K/Akt/mTOR, and chromatin remodeling complexes. TP53MUT tumors more likely had mutations related to fibroblast growth factor, epidermal growth factor receptor, other receptor tyrosine kinases, and cyclin and cyclin-dependent kinases.

Conclusion

The mutational profiles of GCs and GEJs varied according to TP53 mutation status. These mutational differences can be used when designing future studies assessing the predictive ability of TP53 mutation status when targeting differentially affected molecular pathways.

Pathological outcomes of pancreatic adenocarcinoma (PA) after preoperative high biological effective dose (BED) magnetic resonance image-guided radiation therapy (MRgRT)

573

Background: Pre-operative radiotherapy (RT) for PA has the potential to reduce positive surgical margin rates and increase pathologic tumor response, which has been associated with improved survival. Increasing the BED can improve local control and overall survival for patients with unresectable PA. Use of stereotactic body radiation therapy (SBRT) to achieve a higher BED has been limited by toxicity to adjacent radiosensitive structures, but this can be mitigated by MRgRT. We describe our use of MRgRT prior to potentially curative resection of localized PA. Methods: We performed a single institution retrospective analysis of all patients with localized PA who received high BED SBRT on the MR Linac followed by surgical resection with curative intent. Toxicity was evaluated according to Common Terminology Criteria for Adverse Events, version 5.0. Tumor response was evaluated according to the College of American Pathologists tumor regression grading criteria (CAP-TRG), ranging from CAP 0 indicating pathologic complete response to CAP grade 3 indicating no response. Ordinal logistic regression model was used to assess the association between time from RT to surgery and TRG. Follow up included MRI or CT scans at least every three months. Results: We analyzed 26 patients with borderline resectable (80.8%), locally advanced (11.5%), and resectable (7.7%) tumors who received high BED MRgRT followed by surgical resection. Median age at diagnosis was 68 years (34 - 86). Most patients received chemotherapy (80.8%) prior to RT, with 81% of these receiving FOLFINIRNOX and 19% receiving gemcitabine/nab-paclitaxel. All patients received MR-guided high BED SBRT to a median dose of 50 Gy (40 - 50) in 5 fractions. On-table adaptive replanning was performed in 88% of patients, with 74% having all 5 fractions adapted. No acute grade 2+ toxicity associated with RT was observed. The median time to resection was 50 days (37 – 115), and the procedure types included: Whipple (69%), distal (23%), or total pancreatectomy (8%). The R0 resection rate was 96% and no perioperative deaths occurred within 90 days. Complete (0) or near-complete (1) pathologic response was observed in 35% of cases and the time from RT to surgery was positively associated with TRG (R2= 0.22, p = 0.0003). The median follow-up after RT was 16.5 months (3.9- 26.2) during which 9 patients recurred, and 3 patients died of disease. The derived median progression-free survival from RT was 13.2 months. Conclusions: These initial pathology outcomes following high BED MR-guided SBRT are encouraging and suggest that the time from SBRT to surgical resection is associated with response. This finding is consistent with results from other preoperative GI tumor sites and results from prospective studies using high BED SBRT with MRI guidance in combined modality therapy against PA are eagerly awaited.

Multi-institutional outcomes of patients aged 75 years and older with pancreatic ductal adenocarcinoma treated with ablative 5-fraction stereotactic magnetic resonance image-guided adaptive radiation therapy (SMART)

569

Background: Dose escalated radiation therapy (RT) may improve long-term clinical outcomes compared to standard radiation dose for patients with initially inoperable pancreatic ductal adenocarcinoma (PDAC). Favorable outcomes have recently been reported of ablative stereotactic magnetic resonance image-guided adaptive radiation therapy (SMART) delivered in 5 fractions. The appropriateness of ablative SMART inoperable PDAC patients with advanced age (>75 years) is not well understood. Methods: A retrospective analysis was performed of inoperable non-metastatic PDAC patients aged 75 year or older treated on a 0.35T-MR Linac at two institutions. Patients were excluded who did not have at least 3 months follow up after SMART. Fiducial markers were not used. Treatment delivery was typically in breath hold. Most (65.3%) were treated to gross disease only without elective coverage. On-table adaptive replanning was performed for each fraction if needed, primarily to account for interfraction anatomic changes and ensure all organ-at-risk (OAR) constraints were met. Treatment response was defined using RECIST 1.1 criteria and CTCAE v5 criteria was used to assess toxicity. Results: 49 patients were evaluated with median age of 81 years (range 75-91). ECOG performance status (PS) was 0-1 in 89.8%. PDAC was locally advanced (46.9%), borderline resectable (36.7%), or medically inoperable (16.3%). Median CA19-9 at diagnosis was 235.8 U/mL. Most received induction chemotherapy (83.7%), usually gemcitabine/nab-paclitaxel (63.3%) and rarely FOLFIRINOX (12.2%), for a median 3.2 months. Median prescribed dose was 50 Gy (range, 40-50 Gy). Surgery was performed in 18.4% after a median 10 weeks from SMART, all having negative margins. Median follow-up was 14 months from diagnosis. Median and 1-year local control (LC) was 29 months and 88.9%, respectively. Median and 1-year progression free survival (PFS) was 13 months and 53.8%, respectively. Median and 1-year estimated overall survival (OS) was 23 months and 78.9%, respectively. ECOG PS < 2 was the only significant predictor of improved OS on multivariate analysis with a trend towards significance for induction chemotherapy >3 months. Acute and late grade 3+ toxicity rates were 8.2% and 4.1%, respectively. Conclusions: Ablative 5-fraction SMART is associated with encouraging long-term LC and OS among elderly patients with PDAC. This novel treatment strategy is noninvasive, does not require anesthesia, is remarkably well tolerated among patients with advanced age despite the high prescription dose, and therefore should be strongly considered especially among older patients who have limited treatment options.

Delta radiomics analysis of Magnetic Resonance guided radiotherapy imaging data can enable treatment response prediction in pancreatic cancer

Background

Magnetic Resonance Image guided Stereotactic body radiotherapy (MRgRT) is an emerging technology that is increasingly used in treatment of visceral cancers, such as pancreatic adenocarcinoma (PDAC). Given the variable response rates and short progression times of PDAC, there is an unmet clinical need for a method to assess early RT response that may allow better prescription personalization. We hypothesize that quantitative image feature analysis (radiomics) of the longitudinal MR scans acquired before and during MRgRT may be used to extract information related to early treatment response.

Methods

Histogram and texture radiomic features (n = 73) were extracted from the Gross Tumor Volume (GTV) in 0.35T MRgRT scans of 26 locally advanced and borderline resectable PDAC patients treated with 50 Gy RT in 5 fractions. Feature ratios between first (F1) and last (F5) fraction scan were correlated with progression free survival (PFS). Feature stability was assessed through region of interest (ROI) perturbation.

Results

Linear normalization of image intensity to median kidney value showed improved reproducibility of feature quantification. Histogram skewness change during treatment showed significant association with PFS (p = 0.005, HR = 2.75), offering a potential predictive biomarker of RT response. Stability analyses revealed a wide distribution of feature sensitivities to ROI delineation and was able to identify features that were robust to variability in contouring.

Conclusions

This study presents a proof-of-concept for the use of quantitative image analysis in MRgRT for treatment response prediction and providing an analysis pipeline that can be utilized in future MRgRT radiomic studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-021-01957-5.

Chemotherapy Versus Chemotherapy Plus Chemoradiation as Neoadjuvant Therapy for Resectable Gastric Adenocarcinoma: A Multi-institutional Analysis

OBJECTIVE

We compare neoadjuvant chemotherapy (CT) to neoadjuvant chemotherapy plus chemoradiation (CRT) for patients with gastric adenocarcinoma (GA).

SUMMARY OF BACKGROUND DATA

The optimal neoadjuvant therapy regimen for resectable GA is not defined.

METHODS

Utilizing data from 2 high-volume cancer centers, we analyzed patients who underwent surgery for localized GA from 1/1/2000-12/31/2017. Standard CT regimens were used according to treatment period. We compared propensity matched cohorts based on age, sex, race, histology, and clinical stage.

RESULTS

Four-hundred five patients (age 62 ± 12 year, 58% male, 56% White) were analyzed. 231 (57%) received CRT and 174 (43%) received CT. Groups differed based on histopathologic characteristics including preoperative stage (p = 0.013). To control for these differences, propensity matched cohorts of 113 CT and 113 CRT patients were compared. CRT had similar frequencies of microscopically negative resections to CT (93% vs 91%, p = 0.81), but higher rates of complete pathologic response (15% vs 4%, p = 0.003) and lower pathologic stage (p = 0.002). Completion of intended perioperative therapy occurred in 63% of CT and 91% of CRT patients (p < 0.001). Median DFS was 45mo (95%CI: 20-70) in the CT group and 113mo (95%CI: 75-151) in the CRT group (p = 0.018). Median OS was 53mo (95%CI: 30-77) versus 120mo (95%CI: 101-138); p = 0.015.

CONCLUSIONS

In this multi-institutional comparison of neoadjuvant CT and CRT for resectable GA, CRT is associated with higher rates of completed perioperative therapy, higher rates of complete pathologic response, lower pathologic stage, and improved survival.Level of Evidence: Level III.

Impact of histology classification on pathologic treatment response and overall survival in distal esophageal cancer patients: a propensity matched analysis

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) has been linked to superior pathologic treatment response compared to esophageal adenocarcinoma (EAC) after neoadjuvant chemoradiation. However, the impact of histology on survival remains unclear. It has been suggested, based on epidemiologic similarities, that distal EAC should be grouped with gastric cancers as an entity distinct from distal ESCC, but there is little data to support this recommendation. We therefore aim to compare pathologic treatment response (PTR) and overall survival (OS) in patients with distal EAC versus distal ESCC.

METHODS

This retrospective cohort study included patients who underwent esophagectomy for distal esophageal malignancy. Histologic sub-groups were matched (1:1) using a propensity-score matching approach. Pre-operative clinical parameters, oncologic outcomes and survival were compared between groups.

RESULTS

1031 distal EC patients, with a median age of 64.4 years and a male preponderance (86.5%), underwent esophagectomy at our institution between 1999 and 2019. 939 (91.1%) patients had a diagnosis of EAC and 92 (8.9%) had ESCC. A higher proportion of ESCC patients were female (26.1% vs. 12.1%; P < 0.01) and non-white (12.0% vs. 3.8%; P < 0.01). Propensity-score sub-analysis identified 75 matched pairs. Rates of pathologic complete response (58.0% vs. 48.9%; P = 0.67) and OS (43.0 vs. 52.0 months; P = 0.808) were not significantly different between matched groups.

CONCLUSIONS

Although traditionally known to have a better overall PTR compared to EAC, ESCC patients in our large series did not show any improvement in PTR or OS. Treatment recommendations for patients with EAC and ESCC should consider tumor location in addition to histology.

GRECO-2: A randomized, phase 2 study of stereotactic body radiation therapy (SBRT) in combination with GC4711 in the treatment of unresectable or borderline resectable nonmetastatic pancreatic cancer (PC)

TPS4175

Background: While systemic treatment of PC has improved, rates of surgical resection - considered optimum treatment - remain low. Patients with un-resectable or borderline PC still have poor outcomes, with both toxicity and disease progression during induction chemotherapy limiting the number eligible for surgery. SBRT practice to enhance margin negative resection or to provide local control, if inoperable after neoadjuvant therapy, has shifted to higher dose delivery (Mellon 2015, Colbert 2018), but timing and appropriate patient selection are under constant debate. SBRT delivery over 50Gy exhibits superior cell killing compared to conventionally fractionated RT but carries potential GI toxicity risk (Zhong 2017). GC4711 is a selective superoxide dismutase mimetic that converts superoxide to hydrogen peroxide. As radiation response modifiers, dismutase mimetics have the potential to increase tumor control without compromising radiation safety (Sishc, AACR 2019). GC4711 consistently augmented tumor control by SBRT in PC experimental xenograft mouse models. In a pilot phase 1/2 trial (GC4419-101), subjects with locally advanced PC were randomized to receive SBRT plus either the selective dismutase mimetic GC4419 or placebo. This pilot trial has demonstrated acceptable safety with SBRT (5 × 10-11Gy), as well as apparent improvements in survival, surgical resection, locoregional control, and time to distant metastases. Altogether, these data support the hypothesis that GC4711 may improve tumor outcomes and the benefit-risk ratio of 5-fraction SBRT delivering 50Gy by improving efficacy without increasing GI-toxicity. Methods: GRECO-2 is a phase 2, multicenter, randomized, double-blind, placebo-controlled study to determine the effect on overall survival of adding GC4711 to SBRT following 4 months of chemotherapy in subjects with un-resectable or borderline non-metastatic PC. Approximately 160 subjects will be enrolled at over 20 sites to receive GC4711 100 mg or placebo IV given as IV infusion over 15 min, prior to each of 5 SBRT fractions of 10Gy). Subjects judged operable will be explored within 8 weeks after SBRT. All subjects will complete 2 additional months of adjuvant chemotherapy. Primary end point is overall survival and secondary endpoints address resection rates, local and distant disease progression, and safety, while exploratory studies include ctDNA, tumor exome/transcriptome sequencing, and immune profiling, patient-reported symptoms (PRO-CTCAE), CA19.9 normalization, and radiomics. Colbert L, Rebueno N, Moningi S et al Advances in Radiation Oncology (2018) 3, 693-700 Mellon EA, Hoffe SE, Springett GM, et al Acta Oncologica, 2015;54:7 Zhong J, Patel K, Switchenko J, et al. Cancer. 2017 Sep 15;123(18):3486-3493. Sishc BJ, Saha D, Story MD. AACR PADC 2019 C52. Clinical trial information: NCT04698915.

Pretreatment CT and PET radiomics predicting rectal cancer patients in response to neoadjuvant chemoradiotherapy

Background

The purpose of this study was to characterize pre-treatment non-contrast computed tomography (CT) and ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) based radiomics signatures predictive of pathological response and clinical outcomes in rectal cancer patients treated with neoadjuvant chemoradiotherapy (NACR T).

Materials and methods

An exploratory analysis was performed using pre-treatment non-contrast CT and PET imaging dataset. The association of tumor regression grade (TRG) and neoadjuvant rectal (NAR) score with pre-treatment CT and PET features was assessed using machine learning algorithms. Three separate predictive models were built for composite features from CT + PET.

Results

The patterns of pathological response were TRG 0 (n = 13; 19.7%), 1 (n = 34; 51.5%), 2 (n = 16; 24.2%), and 3 (n = 3; 4.5%). There were 20 (30.3%) patients with low, 22 (33.3%) with intermediate and 24 (36.4%) with high NAR scores. Three separate predictive models were built for composite features from CT + PET and analyzed separately for clinical endpoints. Composite features with α = 0.2 resulted in the best predictive power using logistic regression. For pathological response prediction, the signature resulted in 88.1% accuracy in predicting TRG 0 vs. TRG 1-3; 91% accuracy in predicting TRG 0-1 vs. TRG 2-3. For the surrogate of DFS and OS, it resulted in 67.7% accuracy in predicting low vs. intermediate vs. high NAR scores.

Conclusion

The pre-treatment composite radiomics signatures were highly predictive of pathological response in rectal cancer treated with NACR T. A larger cohort is warranted for further validation.

The effect of gender on outcomes in esophageal cancer

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Background: Few epidemiological studies address differences in outcomes by gender in locoregional esophageal cancer (LEC) for which the current standard of care is chemoradiation followed by surgical resection. Although male gender is associated with the majority of LEC cases, we sought to determine if gender could impact clinical presentation as well as surgical and oncologic outcomes in our single institution 20 year experience. Methods: A retrospective query of our institution’s IRB-approved database of patients that had surgical therapy between 2008 and 2019 for esophageal cancer (EC) was performed. Patients were stratified by gender and analyzed based on characteristics such as tumor histology, tumor location, clinical stage at presentation, age at diagnosis, receipt of neoadjuvant therapy, surgical intent, surgical complications, length of post-operative hospital stay, response to neoadjuvant therapy, final pathology, and recurrence. Chi-square, ANOVA and Kaplan Meier survival analysis were performed on the previously defined groups. Results: The cohort studied included 1180 patients with resection for EC. Of those, 1005 (85.2%) had adenocarcinoma, 145 (12.3%) had squamous cell cancer (SCC), 10 (0.8%) had adenosquamous carcinoma, and 20 (1.7%) had other histological variants. There were 985 (83.5%) male patients and 195 (16.5%) female patients. SCC was more common in females (29.2% in females vs. 8.9% in males, p = 0.000) and females tended to have tumor location in the upper thoracic esophagus more often (4.7% in females vs. 0.9% of males, p = 0.000). Additionally, females developed surgical complications more often than males (72.2% vs. 64.7%, p = 0.045). Staging at diagnosis (p = 0.508), receipt of neoadjuvant treatment (p = 0.676), and age at diagnosis (65.3 years in males vs. 66.3 years in females, p = 0.934) had no association with gender. Response to neoadjuvant therapy (p = 0.157) and cancer recurrence (p = 0.434) did not have significant associations with gender. The median overall survival was not statistically significantly different but trended to be longer for females (73.4 months in females [95% CI: 51.5-95.4] vs. 47.0 months in males [95% CI: 39.6-54.5], p = 0.160). Conclusions: Based on our high-volume cancer center study, female patients were more likely to have SCC, upper thoracic esophageal lesions, and surgical complications following resection. While univariate analysis did not demonstrate significant differences in overall survival between genders, there are plans to report additional data after controlling for other variables. Further studies are warranted to validate these findings, given the potential for higher prioritization of an organ preservation approach for this patient population.

Early outcomes of irreversible electroporation after stereotactic body radiation therapy for the treatment of locally advanced pancreatic adenocarcinoma (LAPC): A matched pair analysis

410

Background: Outcomes remain poor for those diagnosed with unresectable pancreatic cancer. SBRT and IRE have independently demonstrated high rates of local control and minimal toxicity for patients with locally advanced pancreatic cancer (LAPC). Data is limited regarding safety and efficacy in the sequential use of both therapies. Materials and Methods: A single institution retrospective matched cohort analysis was performed for patients with non-metastatic pancreatic cancer treated with induction chemotherapy and SBRT followed by IRE, compared with patients of the same cohort who did not receive IRE. Patients were paired based on age, tumor stage, GTV D95, CA19-9 prior to SBRT, and chemotherapy type to mitigate selection bias in surgical candidates. Overall survival (OS), progression free survival (PFS), freedom from local failure (FFLF) and freedom from distant failure (FFDF) were the primary outcomes compared via Kaplan-Meier survival analysis with log-rank methods. Results: From July, 2014 to February, 2020 17 patients received SBRT followed by IRE. These patients were matched with 17 patients who received SBRT from January, 2012 to March, 2019. Most patients received neoadjuvant FOLFIRINOX (82.4%) and were AJCC 8 stage III (79.4%). Median age of the overall cohort was 65.5 years and 50% were male. Median dose delivered to 95% of gross tumor volume was 32.61 Gy, and median pre SBRT CA19-9 value was 70.5 U/mL. There were no statistically significant differences in matched characteristics between the two cohorts. Among the SBRT+IRE, the median time between IRE and SBRT was 66 days (range:49-467 days). The median OS, PFS, FFLF, and FFDF for IRE+SBRT vs. SBRT alone from SBRT was 10.8 vs 15.1 months, 9.6 vs. 15.3 months, 15.7 vs. 15.3 months, 15.9 vs. 14.4 months respectively (all P > .10). 11 patients in the entire cohort experienced toxicity as a result of their radiation therapy (35%), with one G3 GIB and one patient experiencing G3 abdominal pain. Among the 17 patients who underwent IRE, nine patients experienced toxicity (53%). Most of these events were G3, with two G4 intestinal bleeds. There was zero mortality in the 90 day period post operatively. Conclusions: In a retrospective cohort,non-selective delivery ofIRE afterSBRT demonstrated no oncological benefit for patients with unresectable pancreatic adenocarcinoma compared to only SBRT. Compared to historical experiences of IRE alone, there was no increase in overall toxicity with the combination of SBRT and IRE. The optimal timing, sequencing, and indications for IRE and SBRT in LAPC remain unknown and are best assessed prospectively. [Table: see text]

Comprehensive evaluation of genomic alterations in patients with gastric and gastroesophageal adenocarcinoma stratified according to TP53 mutation status

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Background: Gastric (GC) and gastroesophageal adenocarcinomas (GEA) are molecularly diverse. Molecular biomarkers of clinical significance have been identified that impact treatment decision making. TP53 is the most frequently altered gene with approximately 50% of patients harboring mutations. However, TP53 mutations have not yet been confirmed as a target of therapeutic benefit. This study aimed to identify distinct genomic alterations that are dominant in TP53 mutated (MUT) versus wild-type (WT) GC and GEA in order to elucidate alternative therapeutic targets within these subsets. Methods: De-identified data for 3741 patients with GC and GEA was obtained from Foundation Medicine. The data obtained were age, gender, tumor mutational burden (TMB), and the distinct genomic alterations noted on DNA sequencing. The dataset was sorted by TP53 mutation status. Differences in mutation frequency were detected using the Fisher’s exact test of independence with a p-value of < 0.01 designated as the cutoff value for statistical significance. Results: The dataset consisted of 2946 GCs and 795 GEAs. TP53 mutations were present in 65.8% of specimens. 61.6% of GCs and 81.4% of GEAs were TP53 MUT positive (p = < .001). Median TMB score and the frequency of tumors with a TMB score > 10 was similar in both TP53 MUT and WT groups. 49 genes had statistically different mutation frequencies in TP53 MUT vs. WT patients. Top co-occurring genetic alterations in TP53 MUT patients included amplification and point mutations in MYC, CCNE1, MET, ERBB2, and EGFR. Amplification and point mutations in MDM2, CDK4, ARID1A, PIK3CA, and ERBB3 were the top co-occurring genetic alterations in TP53 WT patients. Conclusions: There was a high frequency of TP53 mutations in this group of GC and GEA patients, with a higher incidence of TP53 mutations identified in GEA samples. The mutational profiles of these tumors differed according to TP53 mutation status. These differences may be able to serve as the foundation for future clinical investigations.

Harnessing COVID-Driven Technical Innovations for Improved Multi-Disciplinary Cancer Care in the Post-COVID Era: The Virtual Patient Room

Emergence of the COVID-19 crisis has catalyzed rapid paradigm shifts throughout medicine. Even after the initial wave of the virus subsides, a wholesale return to the prior status quo is not prudent. As a specialty that values the proper application of new technology, radiation oncology should strive to be at the forefront of harnessing telehealth as an important tool to further optimize patient care. We remain cognizant that telehealth cannot and should not be a comprehensive replacement for in-person patient visits because it is not a one for one replacement, dependent on the intention of the visit and patient preference. However, we envision the opportunity for the virtual patient “room” where multidisciplinary care may take place from every specialty. How we adapt is not an inevitability, but instead, an opportunity to shape the ideal image of our new normal through the choices that we make. We have made great strides toward genuine multidisciplinary patient-centered care, but the continued use of telehealth and virtual visits can bring us closer to optimally arranging the spokes of the provider team members around the central hub of the patient as we progress down the road through treatment.

Novel MR-Guided Radiotherapy Elective Rotation for Radiation Oncology Trainees

MR-guided adaptive radiation therapy (RT) is emerging as an integral treatment modality for certain applications and is poised to become an exciting opportunity for greater treatment precision and personalization. However, this is still a relatively nascent technology and only a few institutions and programs have access to this technology for clinical use and trainee education. To increase the diversity of elective offerings and improve the understanding of an MR-guided radiotherapy program, we initiated a unique MR-guided radiotherapy elective rotation for radiation oncology residents. During a representative four-week rotation, 21 simulations were completed by the resident on service. A plurality of simulations were for pancreas stereotactic body radiation therapy (SBRT; 48%) and a majority (71%) of simulations were for adaptive treatments. Additionally, 74 adaptive fractions were completed during this month, of which a significant majority (74%) were for pancreas SBRT. Of the non-adaptive fractions, the majority were for prostate SBRT and intensity-modulated radiation therapy (IMRT). Although many programs may offer training in some aspects of MR-guided radiotherapy as trainees rotate through certain disease sites, we hope this may serve as a blueprint to encourage programs with this technology to fully embrace training in essential competencies related to MR-guided radiotherapy. MR-guided radiotherapy has unique challenges that trainees need to understand to deliver treatment safely: geometric uncertainty, MRI to RT isocenter, and uncertainties with voxel size/tracking.

Small Bowel Adenocarcinoma, Version 1.2020, NCCN Clinical Practice Guidelines in Oncology

Small bowel adenocarcinoma (SBA) is a rare malignancy of the gastrointestinal tract that has increased in incidence across recent years. Often diagnosed at an advanced stage, outcomes for SBA are worse on average than for other related malignancies, including colorectal cancer. Due to the rarity of this disease, few studies have been done to direct optimal treatment, although recent data have shown that SBA responds to treatment differently than colorectal cancer, necessitating a separate approach to treatment. The NCCN Guidelines for Small Bowel Adenocarcinoma were created to establish an evidence-based standard of care for patients with SBA. These guidelines provide recommendations on the workup of suspected SBA, primary treatment options, adjuvant treatment, surveillance, and systemic therapy for metastatic disease. Additionally, principles of imaging and endoscopy, pathologic review, surgery, radiation therapy, and survivorship are described.

Toxicity reduction required for MRI-guided radiotherapy to be cost-effective in the treatment of localized prostate cancer

OBJECTIVE

To determine the toxicity reduction required to justify the added costs of MRI-guided radiotherapy (MR-IGRT) over CT-based image guided radiotherapy (CT-IGRT) for the treatment of localized prostate cancer.

METHODS

The costs of delivering prostate cancer radiotherapy with MR-IGRT and CT-IGRT in conventional 39 fractions and stereotactic body radiotherapy (SBRT) 5 fractions schedules were determined using literature values and cost accounting from two institutions. Gastrointestinal and genitourinary toxicity rates associated with CT-IGRT were summarized from 20 studies. Toxicity-related costs and utilities were obtained from literature values and cost databases. Markov modeling was used to determine the savings per patient for every 1% relative reduction in acute and chronic toxicities by MR-IGRT over 15 years. The costs and quality adjusted life years (QALYs) saved with toxicity reduction were juxtaposed with the cost increase of MR-IGRT to determine toxicity reduction thresholds for cost-effectiveness. One way sensitivity analyses were performed. Standard $100,000 and $50,000 per QALY ratios were used.

RESULTS

The added cost of MR-IGRT was $1,459 per course of SBRT and $10,129 per course of conventionally fractionated radiotherapy. Relative toxicity reductions of 7 and 14% are required for SBRT to be cost-effective using $100,000 and $50,000 per QALY, respectively. Conventional radiotherapy requires relative toxicity reductions of 50 and 94% to be cost-effective.

CONCLUSION

From a healthcare perspective, MR-IGRT can reasonably be expected to be cost-effective. Hypofractionated schedules, such a five fraction SBRT, are most likely to be cost-effective as they require only slight reductions in toxicity (7-14%).

ADVANCES IN KNOWLEDGE

This is the first detailed economic assessment of MR-IGRT, and it suggests that MR-IGRT can be cost-effective for prostate cancer treatment through toxicity reduction alone.

Modeling precision genomic-based radiation dose response in rectal cancer

Aim: Genomic-based risk stratification to personalize radiation dose in rectal cancer. Patients & methods: We modeled genomic-based radiation dose response using the previously validated radiosensitivity index (RSI) and the clinically actionable genomic-adjusted radiation dose. Results: RSI of rectal cancer ranged from 0.19 to 0.81 in a bimodal distribution. A pathologic complete response rate of 21% was achieved in tumors with an RSI <0.31 at a minimal genomic-adjusted radiation dose of 29.76 when modeling RxRSI to the commonly prescribed physical dose of 50 Gy. RxRSI-based dose escalation to 55 Gy in tumors with an RSI of 0.31-0.34 could increase pathologic complete response by 10%. Conclusion: This study provides a theoretical platform for development of an RxRSI-based prospective trial in rectal cancer.

Adaptive dose optimization trial of stereotactic body radiation therapy (SBRT) with or without GC4419 (avasopasem manganese) in pancreatic cancer

TPS4670

Background: Local progression causes up to 30% of deaths from pancreatic cancer (PC) and is also a significant source of morbidity. Stereotactic body radiotherapy (SBRT) offers the potential for improved therapeutic index over standard fractionation, but current regimens of 5 fractions of 5-7 Gy/fraction are constrained by nearby organ tolerance and offer only palliation without improving survival. Safe dose escalation may be necessary to improve SBRT efficacy. Avasopasem, a superoxide dismutase mimetic, selectively converts superoxide (O2•-) to hydrogen peroxide (H2O2) and oxygen. O2•-initiates normal tissue damage due to RT. Avasopasem is in a Phase 3 trial (NCT03689712) to reduce RT-induced oral mucositis in head and neck cancer, based on positive results in a randomized Phase 2 trial for that indication (Anderson, JCO 2019). Avasopasem improved the survival of mice receiving 8.5 Gy x 5 to the upper abdomen. Cancer cells are less tolerant to elevated H2O2, and more tolerant to elevated O2•-, than normal cells, and avasopasem demonstrated mechanism-dependent synergy with high dose-fraction RT in a human tumor xenograft with inducible expression of catalase (Sishc, AACR 2018). Thus, adding avasopasem to SBRT may increase both the efficacy and the safety of the latter. Methods: 48 patients with locally advanced PC, who have completed medically-indicated induction chemotherapy, are randomized 1:1 to placebo or avasopasem, 90 mg IV, prior to each of 5 consecutive daily (M-F) SBRT fractions. A phase I/II Late Onset Efficacy/ Toxicity tradeoff (LO-ET) based adaptive design adaptive model drives assignment of SBRT dose escalation in each arm based on a dual endpoint (Gr 3-4 GI toxicity or death; local stable disease or better) by 90 days post SBRT. The planned dose levels are 10, 11 and 12Gy x 5 fractions (BED10 = 100,112.5 and 132Gy, respectively) as an integrated boost to the gross tumor volume (GTV). Primary endpoint: Maximum tolerated dose of SBRT with avasopasem or placebo. Secondary endpoints progression-free survival, response rate, and acute (90 day) and late (12 month) radiation toxicity with avasopasem vs placebo. Exploratory correlative studies include ctDNA, tumor exome/transcriptome sequencing, and immune profiling. Clinical trial information: NCT03340974 .

Predictors of recurrence and implications for overall survival in borderline resectable pancreatic cancer patients treated with total neoadjuvant therapy: A retrospective cohort study

e16781

Background: Borderline resectable pancreatic ductal adenocarcinoma (BR PDAC) is a subset of pancreatic cancer with unique prognostic implications. A multimodality, neoadjuvant therapy (NAT) approach has known benefits such as downstaging tumors, reducing the risk of a positive margin, and treating micrometastatic disease. Patient selection and therapy sequencing are controversial owing to the high risk of recurrence. Therefore, we aimed to identify factors predicting recurrence and overall survival (OS) in BR PDAC patients undergoing NAT. Methods: We identified BR PDAC patients treated with NAT followed by surgery at Moffitt Cancer Center between 2008-2015. We evaluated clinical, demographic, and perioperative factors to identify predictors of recurrence and OS. Statistical analyses were performed with univariate and multivariable Cox regression models. Results: 117 patients with BR PDAC who received NAT were evaluated; 53 (45%) were female and 64 (55%) were male. Of those, 91 (78%) received gemcitabine/xeloda/taxotere and the remainder received other gemcitabine or 5FU regimens. 107 (91%) patients received neoadjuvant radiation, mainly 5-day dose painted SBRT. Post- NAT CA 19-9 normalized in 39 (33%) and 11 (9%) additional patients normalized after surgery. Pathologic treatment effect was appreciated in 85 (73%) patients and pathologic complete response (pCR) was seen in 18 (15%). 95 (81%) patients initiated adjuvant therapy. In multivariable analysis, the strongest predictor of recurrence was higher log(10) post-operative CA 19-9 (HR 2.29; 95% CI, 1.40-3.75). Time from initiation of NAT to surgery ≥ 5 months also predicted recurrence (HR 2.08; 95% CI, 1.16-3.72). In OS analysis, 71 patients had recurrence after multimodality treatment; 61 (86%) died and 10 (14%) were alive. In multivariable analysis, the strongest predictors of prolonged OS from recurrence were female gender (HR 0.47; 95% CI, 0.26-0.84) and presence of a treatment effect (HR 0.37; 95% CI, 0.15-0.93). Conclusions: We observed treatment effects and pCR comparable to other institutions, supporting a multimodality approach to BR PDAC. Higher post-operative CA 19-9 and time to surgery ≥ 5 months from initiation of NAT were associated with an increased risk of recurrence. These data suggest that timely receipt of surgery after completion of NAT may impact recurrence and OS in BR PDAC.

CT-based radiomic features to predict pathological response in rectal cancer: A retrospective cohort study

INTRODUCTION

Innovative biomarkers to predict treatment response in rectal cancer would be helpful in optimizing personalized treatment approaches. In this study, we aimed to develop and validate a CT-based radiomic imaging biomarker to predict pathological response.

METHODS

We used two independent cohorts of rectal cancer patients to develop and validate a CT-based radiomic imaging biomarker predictive of treatment response. A total of 91 rectal cancer cases treated from 2009 to 2018 were assessed for the tumour regression grade (TRG) (0 = pathological complete response, pCR; 1 = moderate response; 2 = partial response; 3 = poor response). Exploratory analysis was performed by combining pre-treatment non-contrast CT images and patterns of TRG. The models built from the training cohort were further assessed using the independent validation cohort.

RESULTS

The patterns of pathological response in training and validation groups were TRG 0 (n = 14, 23.3%; n = 6, 19.4%), 1 (n = 31, 51.7%; n = 15, 48.4%), 2 (n = 12, 20.0%; n = 7, 22.6%) and 3 (n = 3, 5.0%; n = 3, 9.7%), respectively. Separate predictive models were built and analysed from CT features for pathological response. For pathological response prediction, the model including 8 radiomic features by random forest method resulted in 83.9% accuracy in predicting TRG 0 vs TRG 1-3 in validation.

CONCLUSION

The pre-treatment CT-based radiomic signatures were developed and validated in two independent cohorts. This imaging biomarker provided a promising way to predict pCR and select patients for non-operative management.

Clinical factors associated with the development of postoperative atrial fibrillation in esophageal cancer patients receiving multimodality therapy before surgery

Background

The incidence of esophageal cancer (EC) is increasing in the USA. Neoadjuvant therapy for locally advanced cancers followed by surgical resection is the standard of care. The most common post-esophagectomy cardiac complication is atrial fibrillation (AF). New-onset postoperative AF can require a prolonged hospital stay and may confer an overall poorer prognosis. In this study, we seek to identify clinical factors associated with postoperative AF.

Methods

Query of an IRB approved database of 1,039 esophagectomies at our institution revealed 677 patients with EC from 1999 to 2017 who underwent esophagectomy after neoadjuvant treatment. Age, treatment location (primary vs. other), gender, neoadjuvant radiation type [2D vs. 3D vs. intensity modulated radiation therapy (IMRT)], radiation dose, surgery type (transthoracic vs. transhiatal vs. three field), smoking history, coronary artery disease (CAD), chronic obstructive pulmonary disease (COPD), operative time, blood transfusions, fluid management, and length of stay (LOS) were analyzed in relationship to the development of AF. Statistical analysis was performed with SPSS 24.

Results

The mean age of the entire cohort was 64.3 (range, 28-86 years), with a Caucasian and male preponderance (White: 94.5%; male: 83.6%). Of the 677 patients, 14.9% (n=101) developed postoperative AF. Increasing age (P<0.001), increased radiation dose (P=0.034), operative time (P=0.001), and blood transfusions (P=0.027) were associated with AF. LOS was longer in patients with AF than those without AF (10.5 vs. 10.0 days, P=0.001). On multivariate analysis, increasing age (95% CI: 1.023-1.080, P<0.001) and radiation dose (95% CI: 1.000-1.001, P=0.034) remained significant. None of the other parameters assessed were associated with the development of AF.

Conclusions

Increasing age and radiation dose were associated with the development of postoperative AF in this cohort. This study suggests that older patients or patients receiving higher radiation dose should be monitored more closely in the postoperative setting and potentially referred earlier preoperatively for cardio-oncology assessment. Future study is required to determine if modification of current radiation techniques and cardiac dose constraints in this patient population may be warranted.

Clinical Factors and Outcomes of Octogenarians Receiving Curative Surgery for Esophageal Cancer

BACKGROUND

The incidence of esophageal cancer is increasing in the United States. Although neoadjuvant therapy (NAT) for locally advanced cancers followed by surgical resection is the standard of care, there are no clearly defined guidelines for patients aged ≥79 y.

METHODS

Query of an institutional review board-approved database of 1031 esophagectomies at our institution revealed 35 patients aged ≥79 y from 1999 to 2017 who underwent esophagectomy. Age, gender, tumor location, histology, clinical stage, Charlson Comorbidity Index (CCI), NAT administration, pathologic response rate to NAT, surgery type, negative margin resection status, postoperative complications, postoperative death, length of stay, 30- and 90-d mortality, and disease status parameters were analyzed in association with clinical outcome.

RESULTS

The median age of the octogenarian cohort was 82.1 y with a male preponderance (91.4%). American Joint Committee on Cancer clinical staging was stage I for 20% of patients, stage II for 27% of patients, and stage III for 50% of patients, which was not statistically significant compared with the younger cohort (P = 0.576). Within the octogenarian group, 54% received NAT compared with 67% in the younger group (P = 0.098). There was no difference in postoperative complications (P = 0.424), postoperative death (P = 0.312), and recurrence rate (P = 0.434) between the groups. However, CCI was significantly different between the octogenarian and nonoctogenarian cohort (P = 0.008), and octogenarians had shorter overall survival (18 versus 62 mo, P<0.001). None of the other parameters assessed were associated with clinical outcomes.

CONCLUSIONS

Curative surgery is viable and safe for octogenarians with esophageal cancer. Long-term survival was significantly shorter in the octogenarian group, suggesting the need for better clinical selection criteria for esophagectomy after chemoradiation and that identification of complete responders for nonoperative management is warranted.

Phase I study of preoperative capecitabine and lenvatinib with external radiation therapy in locally advanced rectal adenocarcinoma

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Background: Neoadjuvant chemo-radiation is a standard of care for locally advanced rectal cancer. Patients with pathologic complete response (pCR) have improved outcomes with less local and systemic failure. Dual targeting with platelet derived growth factor (PDGF) and vascular endothelial growth factor receptor (VEGFR) in combination with radiation can escalate tumor response with radiation. Lenvatinib is an oral multi-kinase inhibitor and had shown potent anti-tumor activity in xenograft models cultured with human colorectal cancer (CRC) lines. Methods: Patients with stage II or III rectal cancer, confirmed by endoscopic ultrasound or MRI, were recruited in 3 cohorts of 3 patients per dose level, with an expansion cohort at the MTD. Lenvatinib oral daily dose started at 14 mg (cohort 1) and was escalated to 20 mg (cohort 2) followed by 24 mg (cohort 3). In this 3+3 design, patients received dose escalation of lenvatinib with standard doses of capecitabine (850 mg/m2 PO BID) concurrent with external beam radiation on days 1-5 weekly for 28 treatments. Following completion patients underwent surgery in 6-10 weeks. Results: Twenty patients with median age of 55 were enrolled in 3 cohorts (1 patient was ineligible). There were no dose limiting toxicity at the maximum tested dose of lenvatinib (24 mg). Two patients are still awaiting surgery. 12 patients have undergone low anterior resection and 5 patients have had abdominoperineal resection. Therefore, out of 17 patients, 29.4% (5/17) showed pCR, and downstaging was observed in 71% of the patients (12/17). The mean neoadjuvant rectal cancer score (NAR) was 11.4 and median NAR was 8.43. Six patients had grade 3 adverse events (AEs) (1 rectal pain,1 transaminitis, 2 lymphopenia, 1 HTN, 1 with both leukocytosis and hyponatremia). No grade 4 AEs were noted. Most common AEs were hypertension, rectal pain, nausea, diarrhea, fatigue and dermatitis. No peri operative complications were observed. Conclusions: The study shows that the combination of lenvatinib and capecitabine with radiation is well tolerated in locally advanced rectal cancer with promising mean NAR score. The encouraging results will need to be validated in a randomized study. Clinical trial information: NCT02935309.

Radiation-induced hepatitis masquerading as metastatic disease: the importance of correlating diagnostic imaging with treatment planning

We are presenting a 63-year-old Caucasian male who complained of 2 months of progressive dysphagia. Upper endoscopy discovered a mass in the distal esophagus near the gastroesophageal junction. Biopsy was consistent with adenocarcinoma. Endoscopic ultrasound (EUS) showed extension beyond the muscularis propria, with an enlarged paraesophageal lymph node (T3N1). Initial positron emission tomography (PET)/computed tomography (CT) showed hypermetabolic portocaval lymphadenopathy presumed to be metastatic, but otherwise without distant disease extension. Neoadjuvant treatment included induction FOLFOX followed by 5,600 cGy over 28 fractions in combination with 5-FU and oxaliplatin. Approximately 3.5 weeks after completion, a repeat PET/CT revealed reduced uptake in both the primary esophageal mass and regional lymph nodes. Of note there were several new mass-like foci of hypermetabolism in the liver, specifically the left lobe, concerning for metastatic disease. Image-guided biopsy did not show any identifiable lesions, but sampling was performed based on anatomical landmarks. Pathology revealed benign parenchyma with minimal inflammation and mild reactive regeneration. In light of this, the patient proceeded to undergo definitive resection via robotic Ivor-Lewis esophagectomy with only 1 positive lymph node. Given pleural involvement by the tumor, staging was revised to pT4aN1 with final histology characterized as adenosquamous carcinoma. Postoperative course was fairly uneventful, with a mild exacerbation of his chronic heart failure. The patient was discharged on post-operative day 7, with his feeding tube removed at his 2-week post-operative clinic visit. This scenario is of particular educational value from the standpoint that when the post-treatment PET/CT images are registered to the radiotherapy treatment planning CT and dose, the areas of abnormal uptake in the liver fall within the higher dose regions. Given this and the liver biopsy findings, caution should be exercised before declaring progressive disease following radiotherapy without first reviewing the treatment plan.

Intensity-modulated radiotherapy at high-volume centers improves survival in patients with esophageal adenocarcinoma receiving trimodality therapy

The standard of care trimodality therapy for resectable locally advanced esophageal adenocarcinoma is complex and necessitates multidisciplinary care and expertise. In this work, it is hypothesized that facility clinical volume and utilization of intensity-modulated radiotherapy (IMRT) may influence outcomes. The National Cancer Data Base was queried for patients with cT1-4-N0-3 M0 esophageal adenocarcinoma undergoing trimodality therapy from 2004 to 2013 (n = 2445). All patients received chemoradiation followed by esophagectomy at a Commission on Cancer facility. The facility volume was categorized into tertiles: high-volume centers (HVCs) in the highest 25th percentile of cases per year, intermediate-volume centers (IVCs) with the next highest 25th percentile of cases, and low- and very low-volume centers (LVCs) in the lowest 50th percentile. Overall survival (OS) was estimated using Kaplan-Meier methods and Cox proportional hazard regression. Propensity score matching to balance patient characteristics between volume centers was performed. Subgroup analysis was done comparing IMRT versus 3D conformal radiotherapy. The median follow-up was 26 months. Treatment at an HVC (hazard ratio 0.63, 95% CI 0.49-0.81, P < 0.001) was found to be independently associated with improved overall survival in multivariable analysis. Three-year OS was 58.4%, 46.2%, and 47.5% for HVCs, IVCs, and LVCs, respectively (P < 0.001). Patients at HVCs were more likely to receive IMRT over 3D chemoradiation (CRT; OR 3.45, 95% CI 2.4-5.0, P < 0.001). Patients treated using IMRT at HVCs had improved OS compared to those treated at IVCs or LVCs (HR 0.68, 95% CI 0.52-0.90, P < 0.01), while patients treated with 3D CRT at HVCs had no survival advantage over those at IVCs or LVCs (P = 0.28). Patients with locally advanced esophageal adenocarcinoma treated with IMRT and at HVCs appear to have improved survival.

Impact of sarcopenia on outcomes in patients with rectal carcinoma treated with trimodality therapy

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Background: Sarcopenia has been identified as a negative prognostic factor in several gastrointestinal malignancies. We sought to evaluate whether total psoas area (TPA) was predictive of grade ≥ 3 toxicity, recurrence and overall survival in patients with rectal carcinoma who received tri-modality therapy. Methods: After IRB approval, a retrospective analysis of 112 patients with biopsy-proven rectal cancer treated with neoadjuvant chemoradiation followed by surgery and adjuvant chemotherapy was performed. The L4 vertebra was identified on pre-treatment axial CT and the bilateral psoas muscles were manually contoured to determine the skeletal muscle index, which was normalized by height. Sarcopenia was defined as TPA less than the median of the cohort. (< 1463 mm3/m). Acute toxicity was defined as within 3 months of radiation based on Common Terminology Criteria for Adverse Events version 4. Chi-square was used to assess differences between groups. Time to event analysis was estimated by Kaplan-Meier methods followed by log rank comparison. Predictor variables for outcomes were assessed with Cox regression. Results: Median follow-up was 31 months. Female gender was strongly associated with being sarcopenic (P < 0.001) otherwise no other differences in clinical or treatment characteristics were found. 20 patients (17.8%) developed recurrence (95% distant). Patients with sarcopenia had a decreased risk of recurrence (P = 0.048) as well as a longer time to recurrence from radiation (50 vs. 21.4 months, P = 0.006) and surgery (47.2 vs. 17.9 months, P = 0.006). Gender was not associated with risk of recurrence (p = 0.131). On multivariable analysis, absence of sarcopenia was predictive of time to recurrence following radiation (HR 4.7, 95% CI: 1.2-18.8; P = 0.03). The presence of sarcopenia was not associated with overall survival (P = 0.12) or grade ≥ 3 acute toxicity (P = 0.242). Conclusions: In our cohort, patients with sarcopenia appear to have better tumor control when compared to patients without sarcopenia independent of gender, suggesting this may be a predictor of treatment response. However, sarcopenia was not associated with overall survival or probability of having grade ≥ 3 acute toxicity.

Phase I study of preoperative capecitabine and lenvatinib with external radiation therapy in locally advanced rectal adenocarcinoma

694

Background: Despite routine use of neoadjuvant chemoradiation, patients with advanced rectal tumors experience significant rates of treatment failure and recurrence. Radiation resistance is a particular problem. Dual targeting of PDGF and VEGFR (Vascular endothelial cell growth factor receptor) in combination with radiation can enhance tumor response. Lenvatinib inhibits the kinase activities of VEGFR1-3, FGFR1-4, PDGFRα, KIT, and RET and in vivo results show that it effectively delays the growth of human colorectal xenografts. Methods: This is a phase I clinical trial of lenvatinib in combination with capecitabine administered with radiation. Patients with stage II or III rectal cancer confirmed by endoscopic ultrasound or MRI were eligible for the study. In this 3+3 phase I study with 3 cohorts, patients were treated with escalating doses of lenvatinib administered in combination with standard doses of capecitabine (850 mg/m2 PO BID D1-5 weekly for 5 ½ to 6 weeks) and external beam radiation therapy (180 cGY on D1-5 weekly for 5 ½ to 6 weeks). Patients underwent surgery 6-10 weeks after neoadjuvant therapy. Results: Nine patients have been enrolled in the 3 cohorts with the median age of 51 years. Lenvatinib dosing started at 14 mg PO daily (cohort 1) and was safely escalated to 20 mg PO daily (cohort 2) followed by 24 mg PO daily (cohort 3). There were no DLTs at the maximum tested dose of lenvantinib (24 mg). 5 patients have undergone low anterior resection and 4 have had abdominoperineal resection. The pathological complete response (pCR) rate was 33.33%, and downstaging was observed in 100% of patients. Median neoadjuvant rectal cancer score (NAR) was 8.7. Three pts had grade 3 events (2 hypertension (HTN), 1 lymphopenia) without any grade 4 events. Most common AEs were HTN and fatigue. No perioperative complications were observed. Tissues for all pts have been collected for planned correlative studies. Conclusions: This study shows that the combination of lenvatinib with capecitabine, and EBRT is well tolerated. NAR score and downstaging rates are encouraging. Currently we are enrolling 10 additional pts at the maximum tested dose of lenvatinib to further evaluate efficacy and safety. Clinical trial information: NCT02935309.

Pathologic outcomes of systemic therapy followed by stereotactic body radiation therapy (SBRT) for pancreatic cancer (PC) in a novel lateral decubitus treatment position

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Background: Outcomes of multi-fraction stereotactic body radiotherapy (SBRT) for PC report low rates of toxicity and high local control, improving feasibility for combination with more aggressive systemic therapy regimens. However, SBRT in the ablative range poses risk to adjacent normal structures, excluding this option for tumors within 1 cm of a mucosal organ. In this study, we report our initial experience with treatment in the lateral decubitus position. Methods: An IRB retrospective query identified patients with pancreatic body adenocarcinoma treated with systemic chemotherapy followed by SBRT in the lateral decubitis position. SBRT was delivered to the entire gross disease with 30 Gy in 5 fractions with focal dose escalation up to 40 Gy to the tumor/vessel interface (TVI) as long as constraints were met. Patients were explored for resection if no metastasis or progression on restaging scans. The primary endpoints were pathologic response and margin status. Descriptive analysis was performed with SPSS 24. Results: The median age of the cohort was 68.6 (range, 50-83 yrs), with a white (94%) and male (59%) predominance. Initial staging of the 17 patients who met criteria included 10 (59%) patients diagnosed with borderline resectable disease (BRPC) and 7 (41%) with locally advanced disease (LAPC). 7 (41%) patients were treated with FOLFIRINOX, 5 (29%) with gemcitabine/nab-paclitaxel, 4 (24%) with gemcitabine/capecitabine/docetaxel, and 1 (6%) with gemcitabine/paclitaxel preceding SBRT. A median dose of 40 Gy (range, 33-40 Gy) was delivered to the TVI for all patients. 5 BRCP (29%) and 2 LAPC (12%) patients went to surgery, with 6 of these patients undergoing an R0 resection (86%) and 1 BRPC patient with an R1 resection. Pathologic tumor regression grades by the College of American Pathologists guidelines were 14% Grade 1, 71% Grade 2, and 14% Grade 3. Conclusions: Lateral decubitus treatment expands inclusion of pancreatic body patients for SBRT with focal TVI dose escalation leading to margin negative resection and significant partial tumor response, warranting future studies exploring ablative dosing in this position.

Determining optimal follow up for patients with anal cancer following chemoradiation

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Background: U.S. health care is increasingly defined by over expenditure and inefficiency. Optimizing patient follow-up is critical especially in cancers treated with high control rates. The objective of this study was to assess time to disease recurrence or toxicity in a cohort of patients with anal carcinoma in order to optimize patient care. Methods: 140 patients diagnosed with biopsy-proven, non-metastatic anal carcinoma, treated with chemoradiation utilizing IMRT, were identified from an institutional database at our high volume center. After IRB approval, a retrospective study was conducted that evaluated local recurrence (LR), distant metastasis (DM), overall survival (OS), and late ≥ grade three toxicity (LG3T) based on National Cancer Institute Common Terminology for Adverse Events version 4. Patients were followed post-treatment every three months for two years, every six months in years 3-5 then yearly thereafter with imaging per National Comprehensive Cancer Network recommendations. Results: Median age and follow up is 58 years and 27 months, respectively. Patients were staged based on AJCC 8th edition and 24 patients were stage I (17%), 55 stage II (39%) and 61 stage III (44%). The median radiation dose was 54 Gy (range: 40-62.5), and 11% of patients required a radiation break. The two year LC, DMFS, and OS were 93%, 94% and 89% and 5-year LC, DMFS, OS were 92%, 87% and 85% respectively. In total, there were 29 disease or treatment related events: LR occurred in nine patients, DM in 11 patients, and LG3T in nine patients. Overall, 62% of events occurred within year one and 77 % within two years. Stratified by event type, at two years 79% of LR, 64% of DM and 89% LG3T were identified. At the remaining follow-up points after 2 years there was an event incidence rate of 1.4%. Conclusions: The majority of recurrences/toxicities in patients diagnosed with non-metastatic anal carcinoma after chemoradiation occur within the first year, with 77% of any event occurring before year two. The data from individual time points suggest a reduction in follow-up during years 3-5 may provide adequate surveillance. Considering revisions of the current follow-up recommendations could maximize health care resources while also improving patient quality of life.

Prognostic value of nutritional status for esophageal cancer patients undergoing neoadjuvant therapy and resection

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Background: Malnutrition, linked to decreased patient tolerance to chemotherapy and increased rates of therapy-related toxicity, negatively affects cancer prognosis. Esophageal carcinomas (EC) frequently present with dysphagia and significant weight loss which may be exacerbated by neoadjuvant chemoradiation, placing EC patients at an increased risk of malnutrition. We therefore aim to assess the prognostic value of pre-operative malnutrition for esophageal cancer patients undergoing neoadjuvant therapy (NAT). Methods: Query of our institution’s IRB approved database of 1113 EC patients (pts) identified 725 individuals who underwent NAT followed by resection from 1994-2018. Seventy-six pts were considered to be at higher nutritional risk during NAT, as indicated by significant weight loss and enteral feeding tube requirement (ETF+), while 644 did not receive pre-operative feeding tube placement (ETF–). Clinicopathologic characteristics, post-operative outcomes, and survival were compared between ETF+ and ETF– using various statistical methods. Results: Of the included pts, 83% were male with a median age of 64.5 (28-86) years. Between ETF+ (n = 76) and ETF– (n = 644), pt characteristics were balanced in terms of initial stage, age, histology and tumor location. A higher percentage of ETF+ pts had > 5% weight loss before NAT (32 vs. 6%; p < .01). ETF+ was associated with a significantly worse median survival (27 vs. 77 m; p < .01), but not with increased post-operative length of hospital stay (p = .69), complications (p = .20) or tumor recurrence (p = .89). Although completion of chemotherapy (p = .46) and radiation (p = .49) were comparable between ETF+ and ETF–, tumor response was worse in the ETF+ group (71 vs. 60% non-complete response; p = .02). Conclusions: Our results suggest that baseline malnutrition is a risk factor for poor survival and negatively impacts the efficacy of neoadjuvant therapy in EC patients. Poor response to NAT in malnourished patients may stem from impaired immune function. Future prospective studies should evaluate other parameters for nutritional assessment to further assess the impact of malnutrition on tumor regression and survival after NAT.