Short-course Radiotherapy Research Articles

Neoadjuvant chemotherapy with or without oxaliplatin after short-course radiotherapy in high-risk rectal cancer: A subgroup analysis from a prospective study.

To evaluate the role of oxaliplatin in neoadjuvant chemotherapy delivered after short-course irradiation. Using oxaliplatin in the above setting is uncertain. A subgroup of 136 patients managed by short-course radiotherapy and 3 cycles of consolidation chemotherapy within the framework of a randomised study was included in this post-hoc analysis. Sixty-seven patients received FOLFOX4 (oxaliplatin group) while oxaliplatin was omitted in the second period of accrual in 69 patients because of protocol amendment (fluorouracil-only group). Grade 3+ acute toxicity from neoadjuvant treatment was observed in 30% of patients in the oxaliplatin group vs. 16% in the fluorouracil-only group (p=0.053). The corresponding proportions of patients having radical surgery or achieving complete pathological response were 72% vs. 77% (odds ratio [OR]=0.88; 95% confidence interval [CI]: 0.39-1.98; p=0.75) and 15% vs. 7% (OR=2.25; 95% CI: 0.83-6.94; p=0.16), respectively. The long-term outcomes were similar in the two groups. Overall and disease-free survival rates at 5 years were 63% vs. 56% (p=0.78) and 49% vs. 44% (p=0.59), respectively. The corresponding numbers for cumulative incidence of local failure or distant metastases were 33% vs. 38% (hazard ratio [HR]=0.89; 95% CI: 0.52-1.52; p=0.68) and 33% vs. 33% (HR=0.78; 95% CI: 0.43-1.40; p=0.41), respectively. Our findings do not support adding oxaliplatin to three cycles of chemotherapy delivered after short-course irradiation.

Delivery of Personalized Care for Locally Advanced Rectal Cancer: Incorporating Pathological, Molecular Genetic, and Immunological Biomarkers Into the Multimodal Paradigm.

Approximately one-third of all newly diagnosed colorectal cancer (CRC) is composed of rectal cancer, with the incidence rising in younger patients. The principal neoadjuvant treatments consist of neoadjuvant short-course radiotherapy and long-course chemoradiation. Locally advanced rectal cancer (LARC) is particularly challenging to manage given the anatomical constrictions of the pelvis and the risk for local recurrence. In appropriately treated patients, 5- and 10-year overall survival is estimated at 60 and 50%, respectively. The prognosis for LARC has improved in recent years with more access to screening, advances in surgical techniques, and perioperative care. Furthermore, the refinement of the multidisciplinary team with combined-modality management strategies has improved outcomes. These advancements have been augmented by significant improvements in the understanding of the underlying tumor biology. However, there are many instances where patient outcomes do not match those for their tumor stage and accurate prognostic information for individual patients can be difficult to estimate owing to the heterogeneous nature of LARC. Many new combinations of chemotherapy with radiotherapy, including total neoadjuvant therapy with targeted therapies that aim to diminish toxicity and increase survival, are being evaluated in clinical trials. Despite these advances, local recurrence and distant metastasis remain an issue, with one-third of LARC patients dying within 5 years of initial treatment. Although much of the new pathological, molecular genetics, and immunological biomarkers allow refinement in the classification and prognostication of CRC, the relative importance of each of these factors with regards to the development and progression of LARC remains incompletely understood. These factors are often insufficiently validated and seldom consider the individual characteristics of the host, the tumor and its location, the local available expertise, or the probable location of recurrence. Appreciating the mechanisms behind these differences will allow for a more comprehensive, personalized approach and more informed treatment options, leading to ultimately superior outcomes. This review aims to first outline the current multidisciplinary context in which LARC care should be delivered and then discuss how some key prognosticators, including novel histopathological, molecular genetics, and immunological biomarkers, might fit into the wider context of personalized LARC management in the coming years.

Abstract CT234: Phase I study of epacadostat added to preoperative chemoradiation in patients with locally advanced rectal cancer

Abstract Background: Epacadostat is an orally active, potent and selective inhibitor of indoleamine 2, 3-dioxygenase 1 (IDO1). IDO1 inhibition enhances cytotoxic T cell activation by dendritic cells, and significantly decreases regulatory T cell proliferation. We developed preclinical data supporting combination of epacadostat with radiation therapy in rectal cancer. In rectal cancer samples obtained from patients who received hypofractionated radiation, IDO1 was overexpressed in tumor tissue as compensatory response after radiation in both microsatellite stable and unstable cell lines. IDO1 inhibition with epacadostat selectively reduced survival of cancer cells and enhanced radiosensitivity without impacting normal epithelial cells. Epacadostat in addition to radiation showed both increased tumor cytotoxicity and enhanced immune activation in tumor microenvironment in a syngeneic mouse model of colorectal cancer. Literature also supports the choice of high dose, hypofractionated radiation to induce a more favorable anti-tumor immune response. Therefore, we hypothesized that IDO1 expression is a mechanism of radioresistance in rectal cancer and IDO1 inhibition is a safe and well-tolerated combination therapy to enhance tumor radiosensitivity. Methods: Patients with locally advanced rectal cancer who are candidates for neoadjuvant therapy using short-course radiation and chemotherapy are included in this study. Primary objective of the study is to determine the recommended phase II dose (RP2D) of epacadostat for combination with short course radiation and chemotherapy in preoperative treatment of locally advanced rectal cancer. This study includes dose-escalation part of patients receiving epacadostat with radiation and chemotherapy (n=6-18) followed by dose-expansion (n=up to 27 including those treated at RP2D during escalation). Two dose levels of epacadostat (300mg and 600mg orally twice daily) will be explored. Epacadostat will be combined with short-course radiation (5Gy x 5 fractions) followed by 6 cycles of CAPOX chemotherapy, until the day of surgery for a total of approximately 24 weeks of therapy. Research biopsies of tumor and adjacent non-tumor tissue along with blood sample collection will be performed before and after the radiation, and at the time of surgery. Tryptophan pathway metabolites, immune checkpoint biomarkers, markers of cell death, proliferation and potentially prognostic molecular biomarkers will be measured in tumor tissues before and after radiation therapy. In addition, patient-derived organoid and xenograft models from rectal biopsy samples will be used to determine the success rate of organoid generation, to evaluate treatment response and to characterize molecular changes to identify potential predictors of response and mechanisms of resistance. Enrollment began in November 2019. NCT03516708 Citation Format: Haeseong Park, Ebunoluwa Otegbeye, Hyun Kim, Matthew Mutch, Katrina Pedersen, Manik Amin, Benjamin Tan, Nikolaos Trikalinos, Kian-Huat Lim, Olivia Aranha, Rama Suresh, Shahed Badiyan, Matthew Silviera, Lauren Henke, Paul Wise, Steven Hunt, Jonathan Mitchem, Esther Lu, Andrea Wang-Gillam, Matthew Ciorba. Phase I study of epacadostat added to preoperative chemoradiation in patients with locally advanced rectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT234.

Prognostic Significance of Neoadjuvant Rectal Scores in Preoperative Short-Course Radiotherapy and Long-Course Concurrent Chemoradiotherapy for Patients with Locally Advanced Rectal Cancer.

This study aimed to investigate the prognostic factors and the utility of the neoadjuvant rectal (NAR) score for patients who have locally advanced rectal cancer (LARC) treated with preoperative short-course radiotherapy (SRT) or long-course concurrent chemoradiotherapy (CRT). Of 314 consecutive stage 2 or 3 rectal cancer patients enrolled from January 2006 to December 2017, 205 underwent preoperative SRT (2500cGy/5 fractions), and 109 underwent preoperative CRT (4200-5080cGy/21-28 fractions) after total mesorectal excision (TME). The study calculated NAR scores using the following equation: [5 pN - 3(cT - pT) + 12]2/9.61. The multivariate analysis showed that age above 65years, pT4, pN2, NAR scores higher than 16, and distance from anal verges (< 8cm) were significant prognostic factors for overall survival (OS), whereas, pN2, NAR scores lower than 16, and distance from anal verges (< 8cm) were significant prognostic factors for disease-free survival (DFS) and distant metastasis (DM). The patients with an NAR score higher than 16, had a 5-year OS rate of 67.6%, a DFS rate of 56.9%, a locoregional recurrence (LRR) rate of 7.7%, and a DM rate of 35% compared with corresponding rates of 87.6%, 76.7%, 5.4%, and 7.2% for the patients with an NAR score of 16 or lower (p < 0.001 for OS, < 0.001 for DFS, 0.25 for LRR, and < 0.001 for DM). For patients who undergo SRT or CRT for LARC, a higher NAR score is associated with worse OS and DFS and higher DM rates at 5years. The NAR score could be used as a short-term surrogate end point after neoadjuvant therapy for LARC.

Short-course radiotherapy promotes pro-inflammatory macrophages via extracellular vesicles in human rectal cancer.

BackgroundTumor-associated macrophages (TAM) constitute the most abundant immune cells in the tumor stroma initiating pro-inflammatory (M1) or immunosuppressive (M2) responses depending on their polarization status. Advances in tumor immunotherapy call for a detailed understanding of potential immunogenic mechanisms of irradiation routinely applied in rectal cancer patients.MethodsTo test the effects of radiotherapy on TAM, we ex vivo irradiated tissue samples of human rectal cancer and assessed the phenotype by flow cytometry. We furthermore evaluated the distribution of leucocyte subsets in tissue sections of patients after short-course radiotherapy and compared findings to non-pretreated rectal cancer using an immunostaining approach. Organotypic assays (OTA) consisting of macrophages, cancer-associated fibroblast and cancer cell lines were used to dissect the immunological consequences of irradiation in macrophages.ResultsWe demonstrate that short-course neoadjuvant radiotherapy in rectal cancer patients is associated with a shift in the polarization of TAM towards an M1-like pro-inflammatory phenotype. In addition, ex vivo irradiation caused an increase in the phagocytic activity and enhanced expression of markers associated with stimulatory signals necessary for T-cell activation. In OTA we observed that this alteration in macrophage polarization could be mediated by extracellular vesicles (EV) derived from irradiated tumor cells. We identified high mobility group box 1 in EV from irradiated tumor cells as a potential effector signal in that crosstalk.ConclusionsOur findings highlight macrophages as potential effector cells upon irradiation in rectal cancer by diminishing their immunosuppressive phenotype and activate pro-inflammation. Our data indicate that clinically applied short-term radiotherapy for rectal cancer may be exploited to stimulate immunogenic macrophages and suggest to target the polarization status of macrophages to enhance future immunotherapeutic strategies.

Practical recommendation for treatment of patients with colon cancer during covid-19 pandemic

Restrictions on the cancer care in an epidemic are observed in the most countries of the world. The first small publications gave information of the increased susceptibility of cancer patients to a new infection which led to the postpone of elective surgery, initiation of adjuvant therapy, and the transfer of specialist consultations to telemedicine. The cases of infections of medical personnel, as well as the reassignment of clinical units and clinics that previously assisted cancer patients to the treatment of patients with COVID-19, also contributed. This article presents the experience of treating viral infections in cancer patients from different countries. On the example of colon cancer, treatment approaches are considered that, in conditions of increased epidemic danger, will allow our patients to provide effective antitumor treatment. We recommend to use short course of radiotherapy with chemotherapy in patients with locally-advanced rectal tumors; short course of adjuvant chemotherapy in stage 3 colon cancer; rational decisions for choosing regimen in 1st and subsequent lines of systemic therapy in patients with metastatic disease.

The UPMC Hillman Cancer Center Approach to the Management of Colorectal Cancer During the COVID-19 Pandemic Era

The UPMC Hillman Cancer Center Approach to the Management of Colorectal Cancer During the COVID-19 Pandemic Era

Temozolomide and seizure outcomes in a randomized clinical trial of elderly glioblastoma patients.

Tumor-related epilepsy may respond to chemotherapy. In a previously-published multi-centre randomized clinical trial of 562 elderly glioblastoma patients, temozolomide plus short-course radiotherapy conferred a survival benefit over radiotherapy alone. Seizure outcomes were not reported. We performed an unplanned secondary analysis of this trial's data. The trial design has been previously reported. Seizures were recorded by clinicians as adverse events and by patients in quality of life questionnaires. A Chi-square test of seizure rates between the two groups (α = 0.05) and a Kaplan-Meier estimator of time-to-first self-reported seizure were planned. Almost all patients were followed until they died. In the radiotherapy alone group, 68 patients (24%) had a documented or self-reported seizure versus 83 patients (30%) in the temozolomide plus radiotherapy group, Chi-square analysis showed no difference (p = 0.15). Patients receiving radiotherapy alone tended to develop seizures earlier than those receiving temozolomide plus radiotherapy (p = 0.054). Patients with seizures had shorter overall survival than those without seizures (hazard ratio 1.24, p = 0.02). This study was not powered to detect differences in seizure outcomes, but temozolomide seemed to have minimal impact on seizure control in elderly patients with glioblastoma. NCT00482677 2007-06-05.

Should Short-Course Neoadjuvant Radiation Therapy Be Applied for Low-Lying Rectal Cancer? A Systematic Review and Meta-Analysis of the Randomized Trials

National Comprehensive Cancer Network guidelines recommend either long-course chemoradiation (LC) or short-course radiation (SC, 5 × 5 Gy) for rectal cancer before total mesorectal excision. However, they do not recommend SC for low-lying tumors. As early toxicity of SC is lower than that of LC, and postoperative complications as well as late toxicity are similar, the probable reason is a notion that for low-lying tumors LC may be more effective than SC in assuring local control. A systematic review and meta-analysis of the randomized trials comparing SC with LC was performed to test the hypothesis that for low-lying tumors, LC is superior to SC in reducing the risk of local failure. The systematic search identified 4 trials including, in total, 421 patients with tumors <5 cm from the anal verge; 221 were randomized to SC and 200 to LC. The meta-analysis showed that the difference in local failure rate between SC and LC was insignificant; the pooled odds ratio was 0.87, 95% confidence interval 0.53 to 1.44, P = .59. Heterogeneity between trials was insignificant; I2 = 0.0%, P = .47. Our meta-analysis does not support the notion that LC given before total mesorectal excision is superior to SC in reducing the risk of local failure in low-lying tumors.

P-130 Short course pelvic radiotherapy for localized and oligometastatic rectal adenocarcinoma: The Mayo Clinic experience

Variations in practice amongst radiation oncologists exist on the choice between short-course radiotherapy (SCRT) and long-course chemoradiation as neoadjuvant therapy for rectal cancer. Few data are available on clinical outcomes of SCRT based on a cohort with modern staging and radiotherapy (RT) techniques.

P-14 Dose escalated short-course radiotherapy in rectal cancers: Is this the way forward?

Locally advanced rectal cancer merits neoadjuvant treatment, either with chemoradiotherapy (CRT) or short-course radiotherapy (SCPRT), followed by total mesorectal excision (TME) with negative margins to avoid locoregional recurrences and improve survival. Pathological complete response (pCR) following radiotherapy correlates with better local control, disease-free survival, and overall survival. The non-inferiority of SCPRT to CRT is now accepted. However, strategies to improve pCR in SCPRT have not been established.

Trimodal Therapy Approaches for Localized Rectal Cancer

Excellent long-term outcomes and manageable toxicity are being achieved with contemporary treatment strategies for rectal cancer. Short-course radiotherapy is now an acceptable standard. Total neoadjuvant therapy (TNT), which incorporates induction or consolidation chemotherapy, has improved the delivery of treatment regiments. TNT is now a standard of care, although the sequencing of radiation and chemotherapy in TNT, appropriate amount of chemotherapy in TNT, and addition of irinotecan to the regimen are still being debated. Nonoperative management of rectal cancer appears to be a safe option for select patients, but it is not yet an NCCN recommendation. In addition, the omission of radiation is being evaluated as a treatment option in some cases.

Accelerated Hypofractionated Whole Breast Radiotherapy for Early Breast Cancer; ARandomized Phase III Clinical Trial

To compare the cosmetic outcome and acute cutaneous, cardiac, and pulmonary toxicity profile of accelerated hypofractionated and conventional whole breast radiotherapy (WBRT).This was a blocked randomized, clinical trial on women with early-stage node-negative invasive breast cancer after breast conservation surgery (BCS) with clear margins randomly assigned to receive WBRT either at a conventional dose of 50.0 grays (Gy) in 25 fractions (the conventional group) or at a dose of 42.5 Gy in 16 fractions (the hypofractionated group). Boost irradiation was permitted in both groups. Data were analyzed by SPSS V21.0 using Mann–Whitney U, independent-samples t- and Chi-Square/Fisher's exact tests at the level of P≤0.05.The median follows up was 16 months. Forty-one patients in the conventional WBRT arm and 45 patients in the hypofractionated WBRT group were enrolled. No significant difference was observed in terms of left and right ventricle systolic dysfunction and diastolic dysfunction. Pulmonary function tests after 6 and 12 months follow up, were comparable in both groups (P=0.2). Skin toxicity during and after treatment was acceptable in both groups. Breast size change in the conventional and the hypofractionated WBRT groups was 14.3% and 7.1%, respectively (P=0.6). Excellent or good cosmetic outcome was similar in both groups.The results of our study support the use of accelerated hypofractionated WBRT in women with invasive breast cancer less than five cm and node-negative after breast-conserving surgery, which provides a more convenient shorter course of radiotherapy with a comparable cosmetic outcome and cutaneous, cardiac, and pulmonary toxicity profile.

Short-course versus long-course neoadjuvant chemoradiotherapy in patients with rectal cancer: preliminary results of a randomized controlled trial.

PurposeColorectal cancer is becoming an increasing concern in the middle-aged population of Iran. This study aimed to compare the preliminary results of short-course and long-course neoadjuvant chemoradiotherapy treatment for rectal cancer patients.Materials and MethodsIn this clinical trial we recruited patients with rectal adenocarcinoma located from 5 cm to 15 cm above the anal verge. Patients in group I (short-course) received three-dimensional conformational radiotherapy with a dose of 25 Gy/5 fractions in 1 week plus concurrent XELOX regimen (capecitabine 625 mg/m2 from day 1–5 twice daily and oxaliplatin 50 mg/m2 on day 1 once daily). Patients in group II (long-course) received a total dose of 50–50.4 Gy/25–28 fractions for 5 to 5.5 weeks plus capecitabine 825 mg/m2 twice daily. Both groups underwent consolidation chemotherapy followed by delayed surgery at least 8 weeks after radiotherapy completion. The pathological response was assessed with tumor regression grade.ResultsIn this preliminary report on complications and pathological response, 66 patients were randomized into two study groups. Mean duration of radiotherapy in groups I and II was 5 ± 1 days (range, 5 to 8 days) and 38 ± 6 days (range, 30 to 58 days). The median follow-up was 18 months. Pathological complete response was achieved in 32.3% and 23.1% of patients in the short-course and long-course groups, respectively (p = 0.558). Overall, acute grade 3 or higher treatment-related toxicities occurred in 24.2% and 22.2% of patients in group I and II, respectively (p = 0.551). No acute grade 4 or 5 adverse events were observed in either group except one grade 4 hematologic toxicity that was seen in group II. Within one month of surgery, no significant difference was seen regarding grade ≥3 postoperative complications (p = 0.333).ConclusionFor patients with rectal cancer located at least 5 cm above the anal verge, short-course radiotherapy with concurrent and consolidation chemotherapy and delayed surgery is not different in terms of acute toxicity, postoperative morbidity, complete resection, and pathological response compared to long-course chemoradiotherapy.

Short-Course Radiotherapy in Locally Advanced Rectal Cancer.

INTRODUCTION:To date, we do not know the best therapeutic scheme in locally advanced rectal cancer when patients are older or have comorbidities.METHODS:In 2009, we established a prospective treatment protocol that included short-course preoperative radiotherapy (RT) with standard surgery +/− chemotherapy in frail patients, mostly older than 80 years or with comorbidities.RESULTS:We included 87 patients; the mean follow-up was 43.5 months (0.66–106.3). Disease-specific survival and disease-free survival at 36 months were 86.3% and 82.8%; at 60 months, they were 78.2% and 78%, respectively, with a local recurrence rate of 2.5%. The rate of late radiotoxicity was 9% in the form of sacral insufficiency fracture and small bowel obstruction with one death. The interval before surgery varied according to the involvement of the mesorectal fascia, but it was less than 2 weeks in 45% of cases. The rate of R0 was 95%. Surgical complications included abdominal wound dehiscence (3.5%), anastomotic leak (2.4%), and reoperations (11.5%). Downstaging was observed in 51% of the cases, regardless of the interval before surgery.DISCUSSION:Therapeutic outcomes in our group of elderly patients and/or patients with comorbidities with neoadjuvant short-course RT are such as those of the general population treated with neoadjuvant RT-chemotherapy, all with acceptable toxicity. Therefore, this treatment scheme, with short-course preoperative RT, would be the most appropriate in this group of patients.

A Prospective Observational Study Comparing Long-Course Conventional Neoadjuvant Chemoradiotherapy with Short-Course Radiotherapy Followed by Consolidation Chemotherapy with Delayed Surgery in Locally Advanced Rectal Cancer.

Background Polish and Australian randomized studies compared short-course radiotherapy (RT) with immediate surgery and long-course chemoradiotherapy (CRT) with delayed surgery. In these studies, similar long-term survival and local control have been reported for both these approaches, but pathological complete response (pCR) is not better with short-course RT. Moreover, studies have shown better tumor downstaging with delayed surgery. In this context, the use of short-course RT with delayed surgery may have some advantages and needs to be tested in clinical trials. Patients and Methods This was a two-arm, prospective, observational study, in which preoperative short-course RT followed by two cycles of chemotherapy was compared with the conventional neoadjuvant CRT in locally advanced rectal cancer. The primary end points were the rate of complete response and toxicity profile. The secondary end points were the rate of R0 resection, overall survival, and progression-free survival. The data obtained from the two arms were analyzed using Pearson’s chi-square test to determine the statistical significance between the two treatment arms. Results The pCR rate was 6.7% in the study arm and 0 in the control arm ( p = 0.343). The RO resection rates were 92.8 and 92.3% in the study and control arms, respectively. The rates of grade 3and 4 acute toxicity in the study and control arms were 14.2 and 61.5%, respectively ( p = 0.011). The rates of grade 3 and 4 late toxicity in the study and control arms were 21.4 and 15.3%, respectively ( p = 0.686). Conclusions The pCR rates and the late toxicities in both arms are comparable. The major advantages of the 5 × 5 Gy regimen with chemotherapy in a neoadjuvant setting are a significant reduction in acute toxicities and better patient compliance along with similar efficacy as that of the standard regimen.

Predictive factors of complete pathological response in patients with locally advanced rectal cancer.

Patients with locally advanced rectal cancer who achieve pathologic complete response (pCR) following neoadjuvant therapy have better long-term outcomes and could be spared from the perioperative and long-term morbidity of rectal resection. The aim of this study was to identify factors that predict the ability to achieve pCR at completion of conventional neoadjuvant therapy, therefore determining their suitability for non-surgical management. A retrospective analysis was performed on data obtained from a prospectively maintained colorectal neoplasia database. Patients treated for biopsy-proven primary rectal adenocarcinoma between January 1, 2010, and February 28, 2018, who received neoadjuvant radiotherapy or chemoradiotherapy and had undergone surgical resection, were included in this study. Five-year oncologic outcome data was also obtained for 144 patients. Clinicopathological tumour characteristics and treatment regimens were analysed for correlation to clinical outcome. Three hundred fifty-four patients met inclusion criteria for this study. We identified significant differences between patients achieving a pCR and those that did not for tumour type (adenocarcinoma vs. mucinous/signet ring; p = 0.008), pre-treatment serum CEA level (</≥ 2.5 μg/L; p = 0.003), neoadjuvant therapy type (short-course radiotherapy and long-course chemoradiotherapy; p = 0.008) and preoperative lymph node status (node-negative versus node-positive disease; p = 0.031). Additionally, this is the first report to our knowledge to identify a significant correlation with pCR and the degree of tumour fixity (mobile vs. fixed/tethered; p = 0.038). This retrospective analysis identified factors that significantly impact a patients' ability to achieve a pCR, which may prove useful for prospectively selecting patients suitable for non-surgical management of disease.

Outcomes of rectal cancer patients treated using Polish II neoadjuvant short course radiation therapy and chemotherapy approach in comprehensive cancer center.

e16088 Background: Neoadjuvant short-course (SC) radiation (RT) followed by fluoropyrimidine based chemotherapy prior to surgery (Polish II approach) is a less utilized treatment in the United States for rectal cancer. Based on data suggesting equivalent or improved outcomes at lower cost compared to the long course neoadjuvant chemoradiation, our team started utilizing this approach for rectal cancer management at Simmons Comprehensive Cancer Center. We aim to document our experience with Polish II approach at NCI-designated comprehensive cancer center program. Methods: A retrospective review of stage I-IV rectal cancer patients, seen at an academic center or the Dallas County safety net hospital and treated at Simmons Comprehensive Cancer Center from Nov 2017 to Dec 2019. Patients were treated with neoadjuvant SC-RT followed by 3 cycles of FOLFOX prior to surgery and followed by adjuvant FOLFOX. Descriptive data for demographic, radiation, chemotherapy and surgery, hospitalizations, 30 day post-surgery admission, time to relapse, and laboratory parameters was collected. Results: Thirty-nine patients met the inclusion criteria (average age 58 years; 74% men/26% women). Forty-six percent of patients were Hispanic, 28.2% White, 15.4% African American and 7.7% Asian. The majority of patients had stage IIIB (46.2%), followed by IIIC (17.9%), IIA (12.8%), IIIA (7.7%), while rest were stage I, IVA or unknown (5.1%). All patients received 5 x 5 SC-RT, 100% completed 3 cycles of planned neoadjuvant FOLFOX (12.8% received 4-8 cycles) and 36/39 (92%) of patients underwent planned surgery. Median duration from SC-RT to chemotherapy was 12 days, and from chemotherapy to surgery was 37 days. Hospitalization occurred in 3 patients (7.7%) during neoadjuvant therapy, and in 8 patients (20.5%) within 30 days post-surgery. Complete pathological response was seen in 6 patients (16.6%) and near-complete pathological response in 3 patients (8.3%). Relapse occurred in 10.3% patients at time of data acquisition. Grade 3 and 4 neutropenia, anemia, and thrombocytopenia in neoadjuvant phase was observed in 8.6%, 25.7%, and 2.8% patients, respectively. Conclusions: In rectal cancer patients treated at a comprehensive cancer center, neoadjuvant Polish-II approach was feasible and well tolerated. Pathological response rates were comparable to historical data. SC-RT based neo-adjuvant therapy approach should be favored due to lower pelvic radiation dose, tolerance and convenience to patients.

Short-course radiotherapy followed by chemotherapy before TME in locally advanced rectal cancer: The randomized RAPIDO trial.

4006 Background: Local control in locally advanced rectal cancer (LARC) has improved. However, systemic relapses remain high even with postoperative chemotherapy, possibly due to low compliance. Short-course radiotherapy (SCRT) followed by delayed surgery with, in the waiting period, chemotherapy, may lead to better compliance, downstaging and fewer distant metastases. The main objective of the international multicenter phase III RAPIDO trial is to decrease Disease-related Treatment Failure (DrTF), defined as locoregional failure, distant metastasis, a new primary colon tumor or treatment-related death, by reducing the risk of systemic relapse without compromising local control. Methods: MRI-diagnosed LARC patients with either cT4a/b, extramural vascular invasion, cN2, involved mesorectal fascia or enlarged lateral lymph nodes considered to be metastatic were randomly assigned to SCRT (5x5 Gy) with subsequent six cycles of CAPOX or nine cycles of FOLFOX4 followed by total mesorectal excision (TME) (experimental arm) or, capecitabine-based chemoradiotherapy (25-28 x 2.0-1.8 Gy) followed by TME and optional, predefined by hospital policy, postoperative eight cycles of CAPOX or twelve cycles of FOLFOX4 (standard arm). Results: Between June 2011 and June 2016, 920 patients were randomized. Pathological complete response rates were 27.7% vs 13.8% (OR 2.40 [1.70 – 3.39]; p &lt; 0.001) in the experimental and standard arms, respectively. At three years, cumulative probability of DrTF was 23.7% in the experimental arm and 30.4% in the standard arm (HR 0.76 [0.60 – 0.96]; p = 0.02). Probability at three years of distant metastasis and locoregional failure were, in the experimental and standard arms, 19.8% vs 26.6% (HR 0.69 [0.53 – 0.89]; p = 0.004) and 8.7% vs 6.0% (HR 1.45 [0.93 – 2.25]; p = 0.10), respectively. No differences in DrTF between hospitals with or without policy for postoperative chemotherapy were found (p = 0.37). Overall health ( p = 0.192), quality of life ( p = 0.125) and low anterior resection syndrome score ( p = 0.136) were comparable between the two treatment arms. Conclusions: A lower rate of DrTF, as a result of a lower rate of distant metastases, in high-risk LARC patients can be achieved with preoperative short-course radiotherapy, followed by chemotherapy and TME than by conventional chemoradiotherapy. In addition, the high pCR rate, achieved with the experimental treatment regimen can contribute to organ preservation. This treatment can be considered as a new standard of care. Clinical trial information: NCT01558921 .

Phase II study of durvalumab plus total neoadjuvant therapy (TNT) in locally advanced rectal cancer: The GEMCAD-1703 DUREC trial.

TPS4122 Background: In clinical stages II and III (cT3-4 and/or N+), preoperative chemoradiotherapy (CRT) or short-course radiation followed by total mesorectal escision (TME) have been the standard of care for the last 15 years. Induction chemotherapy (CT) before CRT (strategy known as TNT) results in fewer toxic effects and improved compliance. TNT may release tumor-neoantigens with platinum-based induction CT, and radiotherapy has the potential ability to induce an immunogenic cell death and counteract an immune-suppressive tumor microenvironment that provides the rationale for combining with immunotherapies. In addition, the presence of tumor infiltrating lymphocytes has been demonstrated in patients with rectal cancer treated with neoadjuvant CRT, reinforcing the rational for immune check-point inhibitors in this setting. We hypothesize that combining TNT with durvalumab (an optimized monoclonal antibody directed against programmed cell death-1 ligand 1) would improve outcome. Methods: DUREC is a multicenter, single-arm, open-label, phase Ib/II study for patients with magnetic resonance (mr) image middle or distal third, mrT3c-d/T4/N2 rectal adenocarcinoma. Treatment: Patients will receive 6 cycles of modified FOLFOX6 prior to CRT (capecitabine with 50.4 Gy in 28 fractions) and TME, combined with durvalumab 1500 mg every 4 weeks during induction CT, CRT and waiting period until surgery. To assess the tolerability and toxicity profile we plan to perform a run-in treatment phase including the first 6 patients in the study, holding recruitment until all of them will be operated and 30-days post-surgery period completed. If ≤ 2 durvalumab-related dose-limiting toxicities (DLTs) are observed, recruitment will continue. The primary objective is pathological complete response (pCR) rate. Secondary endpoints include toxicity, tumor regression grade, R0 resections, clear circumferential margins, surgical complications, NAR score, disease-free survival and a biomarker program on tumor tissue, blood samples and stool microbiota. Statistical design: 58 evaluable patients (assuming a P0 of 16% and a P1 of 30%, with 0.1 alpha and 0.1 beta); Study started recruitment on December 2019. Clinical trial information: 2018-004835-56 .