Pathologic complete response and disease-free survival are not surrogate endpoints for 5-year survival in rectal cancer: an analysis of 22 randomized trials

Early Outcomes of Preoperative Short Course Radiotherapy With Simultaneous Integrated Boost and Response-adapted Chemotherapy for Advanced Rectal Cancer

BACKGROUND AND PURPOSE

Limited evidence exists for dose escalation in neoadjuvant short course radiotherapy (SCRT) for rectal cancer. With enhanced imaging and radiotherapy techniques over the past decades along with the valuable endpoint of pathological complete response (pCR), we believe SCRT with simultaneous integrated boost could potentially provide deeper pathological responses and improve local control.

METHODS AND MATERIALS

Between January 2020 and December 2022, locoregional-advanced rectal cancer patients that were treated with neoadjuvant SCRT with simultaneous integrated boost up to 5.5-6Gy per fraction with five daily fractions followed by response-adapted chemotherapy was retrospectively reviewed. The pCR rates, R0 resection rates, tumor downstaging, toxicities, and early pattern of recurrence are reported.

RESULTS

Among the 76 patients, 67 (88%) were able to undergo curative intent surgery. R0 resection was achieved in 99% (n = 66) of patients with pCR rates of 28% (n = 19). Forty-six percent (n = 31) of patients had significant pathological downstaging (ypT2N0) and 55% (n = 37) of patients had both T and N downstaging. Most common grade 3 or above radiotherapy-related side-effects were proctitis, rectal pain, and dermatitis found in 5% (n = 4), 3% (n = 2) and 3% (n = 2) of patients, respectively. Grade 3 or above surgical complications were observed in 15% (n = 10) of patients. There were no treatment-related deaths. With a median follow-up of 27 months, only 6% (n = 4) had local recurrence after surgery.

CONCLUSIONS

Neoadjuvant short course radiotherapy with simultaneous boost for rectal cancer is feasible with no added toxicities. Patients who underwent surgery achieve a high R0 resection and pCR rates. Early data suggest low rates of locoregional recurrence. Further follow-up and research is needed to validate and optimize the dose, method, and schedule of dose escalation.

Assessment of circulating tumor DNA in patients with locally advanced rectal cancer treated with neoadjuvant therapy

Post-neoadjuvant therapy (post-NAT) and post-surgical circulating tumor DNA (ctDNA) risk stratification may enhance the management of patients with locally advanced rectal cancer (LARC). In this study, we assessed the prognostic value of ctDNA-based MRD detection in LARC patients using a personalized, tumor-informed ctDNA assay. Plasma samples from LARC patients (N = 30) were analyzed retrospectively using the Signatera™ assay. The neoadjuvant rectal (NAR) score was calculated and compared to ctDNA status to predict recurrence risk and survival outcomes. ctDNA-positive patients post-NAT and post-surgery had worse Disease Free Survival (DFS) (HR: 7.82; p = 0.001, HR: 19.65; p = 0.001) when compared to ctDNA-negative patients. In the post-NAT setting, patients who responded to NAT had superior DFS compared to patients who did not clear their ctDNA or showed no radiological response (HR: 24.7, p = 0.001 and HR: 5.1, p = 0.054, respectively). When ctDNA status is used alongside the NAR score in the post-NAT setting, patients who were ctDNA-positive with an intermediate or high NAR score showed significantly worse DFS (HR: 47.5, p < 0.001) compared to ctDNA-negative patients with either a low or intermediate/high NAR score (HR: 9.8, p = 0.0301). Post-NAT ctDNA status, whether used alone or in combination with the NAR score, may predict NAT response, and improve risk stratification.

Significant Pathologic Response Following Neoadjuvant Therapy and Curative Resection in Patients With Rectal Cancer: Surgical and Oncological Outcomes From a Retrospective Cohort Study

AIM

This study evaluated surgical complication rates, recurrence-free survival, overall survival (OS), and stoma status of patients with rectal cancer after significant pathologic response following neoadjuvant treatment and curative resection. Pathologic complete response (pCR) and near-pCR patients constitute patients in our study.

METHODS

Included was a retrospective cohort study of patients with rectal cancer who were diagnosed between July 2011 and September 2022 and who underwent neoadjuvant therapy and surgical resection.

RESULTS

Of 696 patients with rectal cancer, 149 (21.4%) cases achieved significant pathologic response. During the 64 (70.5) months of follow-up, recurrence occurred in 16.1% of patients and distant metastases account for the majority of them. Age (p = 0.014) and receiving adjuvant chemotherapy (p = 0.016) were significantly related to the occurrence of recurrence. The five-year recurrence-free survival (RFS) and OS rates were obtained at 83% and 87%, respectively. Although age and surgical technique were significant factors in univariate Cox regression analysis, none of the candidate variables were significant prognostic factors for RFS in the multiple models. The risk of surgical complications remained in these patients. The most frequent complication attributed to infection (20.8%). Despite the 24.8% presence of permanent stoma at primary surgery, more than 50% of our patients lived without stoma at the last follow-up.

CONCLUSION

Our recurrence rate was about 16%, and it was related to age and adjuvant chemotherapy. These patients achieved over 80% rates of five-year RFS and OS. No significant prognostic factors were found on RFS in the multivariable model. As a matter of course, the risk of surgical complications and permanent stoma has still remained in these patients.

Total Neoadjuvant Therapy for Locally Advanced Rectal Cancer: How to Select the Most Suitable?

Rectal cancer shows specific characteristics in terms of pattern of recurrence, which occurs commonly at both local and distant sites. The standard of care for locally advanced rectal cancer (LARC) including neoadjuvant chemoradiotherapy, followed by surgery based on the total mesorectal excision principles leads to a reduction in the rates of local recurrences to 6-7% at 5 years. However, the outcomes among those with high-risk lesions remain unsatisfactory. On the contrary, neoadjuvant chemoradiotherapy results in long-term morbidities among those with low-risk lesions. Furthermore, the overall survival benefit of neoadjuvant therapy is still a subject to be debated, except for patients with complete or near-complete response to neoadjuvant therapy. Total neoadjuvant therapy (TNT) is a new paradigm of management of high-risk rectal cancer that includes early administration of the most effective systemic therapy either before or after neoadjuvant radiotherapy with or without chemotherapy prior to surgery with or without adjuvant chemotherapy. TNT potentially improves disease-free survival, even though whether it can prolong survival has been debatable. Recently, neoadjuvant chemotherapy only has been proved to be non-inferior to neoadjuvant chemoradiotherapy in patients with low-risk lesions. This review intends to review the current evidences of neoadjuvant therapy and propose a more customized paradigm of management of LARC.

Immunotherapy in Colorectal Cancer - Finding the Achilles' Heel

AbstractColorectal cancer treatment has evolved considerably in the last decade with the development of immunotherapies. Immune checkpoint inhibitor therapies have brisk and durable responses in patients with advanced microsatellite instability-high colorectal cancer, both surgically resectable and unresectable; however, patients with microsatellite stable colorectal cancer in general do not respond to the same therapy. Emerging evidence shows that immune checkpoint inhibitors may elicit responses in subsets of patients with microsatellite stable colorectal cancer, especially when combined with other anticancer agents that can modulate the tumor microenvironment. Therefore, rationally designed therapeutic combinations involving immune checkpoint inhibitors, as well as the development of predictive biomarkers for optimal patient selection, have emerged as two key areas of active research. In addition, other immunotherapeutic agents such as cell-based therapies and bispecific T-cell engagers are beginning to be studied in preclinical and early-phase settings. Although by no means a universal treatment strategy, immunotherapy can elicit responses in microsatellite stable colorectal cancer and further research is needed to extend their benefit to patients with microsatellite stable colorectal cancer. Here, we review the current state of immunotherapeutic regimens for microsatellite stable colorectal cancer.

Early Efficacy End Points in Neoadjuvant Rectal Cancer Trials: Surrogacy Revisited

Trial-level surrogacy is critical before early response endpoints are used to approve new therapies.

Phase II study of capecitabine-based concomitant chemoradiation followed by durvalumab as a neoadjuvant strategy in locally advanced rectal cancer: the PANDORA trial

BACKGROUND

This study investigated the efficacy of chemoradiotherapy (CRT) followed by durvalumab as neoadjuvant therapy of locally advanced rectal cancer.

PATIENTS AND METHODS

The PANDORA trial is a prospective, phase II, open-label, single-arm, multicenter study aimed at evaluating the efficacy and safety of preoperative treatment with durvalumab (1500 mg every 4 weeks for three administrations) following long-course radiotherapy (RT) plus concomitant capecitabine (5040 cGy RT in 25-28 fractions over 5 weeks and capecitabine administered at 825 mg/m2 twice daily). The primary endpoint was the pathological complete response (pCR) rate; secondary endpoints were the proportion of clinical complete remissions and safety. The sample size was estimated assuming a null pCR proportion of 0.15 and an alternative pCR proportion of 0.30 (α = 0.05, power = 0.80). The proposed treatment could be considered promising if ≥13 pCRs were observed in 55 patients (EudraCT: 2018-004758-39; NCT04083365).

RESULTS

Between November 2019 and August 2021, 60 patients were accrued, of which 55 were assessable for the study's objectives. Two patients experienced disease progression during treatment. Nineteen out of 55 eligible patients achieved a pCR (34.5%, 95% confidence interval 22.2% to 48.6%). Regarding toxicity related to durvalumab, grade 3 adverse events (AEs) occurred in four patients (7.3%) (diarrhea, skin toxicity, transaminase increase, lipase increase, and pancolitis). Grade 4 toxicity was not observed. In 20 patients (36.4%), grade 1-2 AEs related to durvalumab were observed. The most common were endocrine toxicity (hyper/hypothyroidism), dermatologic toxicity (skin rash), and gastrointestinal toxicity (transaminase increase, nausea, diarrhea, constipation).

CONCLUSION

This study met its primary endpoint showing that CRT followed by durvalumab could increase pCR with a safe toxicity profile. This combination is a promising, feasible strategy worthy of further investigation.

The neoadjuvant rectal score and a novel magnetic resonance imaging based neoadjuvant rectal score are stage independent predictors of long-term outcome in locally advanced rectal cancer

AIM

Neoadjuvant rectal (NAR) score is an early surrogate for longer-term outcomes in rectal cancer undergoing radiotherapy and resection. In an era of increasing organ preservation, resection specimens are not always available to calculate the NAR score. Post-treatment magnetic resonance imaging (MRI) re-staging of regression is subjective, limiting reproducibility. We explored the potential for a novel MRI-based NAR score (mrNAR) adapted from the NAR formula.

METHODS

Locally advanced rectal cancer patients undergoing neoadjuvant therapy (nCRT) and surgery were retrospectively identified between 2008 and 2020 in a single cancer network. mrNAR was calculated by adapting the NAR formula, replacing pathological (p) stages with post-nCRT MR stages (ymr). Cox regression assessed relationships between clinicopathological characteristics, NAR and mrNAR with overall survival (OS) and recurrence-free survival (RFS).

RESULTS

In total, 381 NAR and 177 mrNAR scores were calculated. On univariate analysis NAR related to OS (hazard ratio [HR] 2.05, 95% confidence interval [CI] 1.33-3.14, p = 0.001) and RFS (HR 2.52, 95% CI 1.77-3.59, p = 0.001). NAR 3-year OS <8 was 95.3%, 8-16 was 88.6% and >16 was 80%. mrNAR related to OS (HR 2.96, 95% CI 1.38-6.34, p = 0.005) and RFS (HR 2.99, 95% CI 1.49-6.00, p = 0.002). 3-year OS for mrNAR <8 was 96.2%, 8-16 was 92.4% and >16 was 78%. On multivariate analysis, mrNAR was a stage-independent predictor of OS and RFS. mrNAR corresponded to NAR score category in only 15% (positive predictive value 0.23) and 47.5% (positive predictive value 0.48) of cases for categories <8 and >16, respectively.

CONCLUSIONS

Neoadjuvant rectal score is validated as a surrogate end-point for long-term outcomes. mrNAR categories do not correlate with NAR but have stage-independent prognostic value. mrNAR may represent a novel surrogate end-point for future neoadjuvant treatments that focus on organ preservation.

The RAPIDO trial-Reduction in disease-related treatment failure does not translate into improved overall survival: a mystery solved!

The initial publication of the RAPIDO trial resulted in widespread adoption of short-course radiotherapy and consolidation chemotherapy in locally advanced rectal cancer. The impressive reduction in disease-related treatment failure did not, however, translate into any overall survival benefit. The recent update of the RAPIDO trial with its 5-year results provides much insight into the actual effect that this approach has on patient outcomes and the detriment in local control leads to the question as to whether this approach can still be considered as standard of care in high-risk rectal cancer.

Randomized controlled trials and alternative study designs in surgical oncology

Surgery is central to the cure of most solid cancers and an integral part of modern multimodal cancer management for early and advanced stage cancers. Decisions made by surgeons and multidisciplinary team members are based on best available knowledge for the defined clinical situation at hand. While surgery is both an art and a science, good decision-making requires data that are robust, valid, representative and, applicable to most if not all patients with a specific cancer. Such data largely comes from clinical observations and registries, and more preferably from trials conducted with the specific purpose of arriving at new answers. As part of the ESSO core curriculum development an increased focus has been put on the need to enhance research literacy among surgical candidates. As an expansion of the curriculum catalogue list and to enhance the educational value, we here present a set of principles and emerging concepts which applies to surgical oncologist for reading, understanding, planning and contributing to future surgeon-led cancer trials.

Total neoadjuvant treatment and organ preservation strategies in the management of localized rectal cancer: A narrative review and evidence-based algorithm

The multimodal approach with total mesorectal excision preceded by neoadjuvant (chemo)radiotherapy represented the mainstay treatment for locally advanced rectal cancer (LARC) for a long time. However, the benefit of adjuvant chemotherapy in terms of distant relapse reduction is limited. Recently, chemotherapy regimens administered before surgery and incorporated with (chemo)radiotherapy in total neoadjuvant treatment protocols have been established as new options in the management of LARC. Meanwhile, patients with clinical complete response to neoadjuvant treatment can benefit from organ preservation strategies, aimed at sparing surgery and long-term post-operative morbidities, while preserving an adequate disease control. However, the introduction of a non-operative management in clinical practice is a matter of debate with some concerns regarding the risk of local recurrence and long-term outcomes. In this review, we discuss how these recent advances are reshaping the multimodal management of localized rectal cancer and propose an algorithm to place them in the clinical practice.

Clinical complete response maintained for more than 5 years after aggressive chemoradiotherapy for advanced rectal cancer with necrotizing fasciitis: a case report

We report the case of a 65-year-old male diagnosed with advanced rectal cancer associated with necrotizing fasciitis (NF). Since radical surgery, total pelvic exenteration with sacrectomy, was rejected because of detrimental effects on quality of life, chemoradiotherapy (CRT) was chosen as anti-cancer treatment after urgent debridement. Although CRT was paused unintentionally just after delivering the total dose of radiation owing to the relapse of NF, the patient has maintained clinical complete response (cCR) without any distant metastasis for >5 years. Advanced rectal cancer is recognized as an NF risk factor. No definitive treatment strategies have been reported for NF-inducing rectal cancer; however, some reports have demonstrated curative extended surgery. Thus, CRT may be a less-invasive treatment option for NF-inducing rectal cancer, whereas severe adverse effects including re-infection after debridement should be closely monitored.

Impact of preoperative chemoradiation with higher dose intensity modulated radiotherapy on pathological complete response for locally advanced rectal cancer: a systematic review

INTRODUCTION

Neoadjuvant chemoradiation (CRT) followed by total mesorectal excision is the current standard-of-care for locally advanced UICC II-III stage rectal cancer (LARC). A pathological complete response (pCR) correlates with survival. Improvements of pCR, including dose escalation, should be explored. The aim of this explorative analysis is to assess the impact on pCR of intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB).

AREAS COVERED

A literature search via PICO (Population, Intervention, Comparison, Outcome) in MEDLINE/PubMed and EMBASE and a systematic review according to PRISMA (Preferred Reporting Items for Systematic Reviews and Metanalysis) methodology were performed. Studies that reported pCR rate in patients with LARC in clinical stage T2N+M0 or cT3/4 N0/+M0 treated with preoperative CRT with SIB-IMRT/VMAT (Volumetric Modulated Arc Therapy) were included. Sixty-two studies were identified, but only eight clinical trials with a total of 311 patients were included . Median follow-up was 16-61 months. pCR reached the value of 38%. Good survival outcomes were observed with a mild toxicity profile.

EXPERT OPINION

Radiotherapy dose intensification in LARC showed a slight increase of pCR compared to historical studies. Prospective evaluations are necessary to define which patients would benefit most.

Three perspectives: the approach to neoadjuvant treatment of rectal cancer according to medical oncologists, radiation oncologists, and surgeons

Background: Two treatment options considered for radiotherapy are short-course radiotherapy and immediate surgery, or chemoradiation with 5-Fluorouracil based chemotherapy and delayed surgery. Aim of the study: Evaluate the real-life treatment approaches of medical, radiation, and surgical oncologists, to neoadjuvant treatment of rectal cancers. Material and methods: An online survey was established via Google Forms. The survey was taken voluntarily by medical oncologists, radiation oncologists, surgical oncologists, and general surgeons. Results: Of those who participated, 183 were medical oncologists, 36 were radiotherapists, and 36 were surgeons. Most of the study population preferred long-course radiation therapy and chemotherapy (85%). Meanwhile, two-thirds of the participants preferred chemotherapy prior to operating. The most frequent chemotherapy cycles for the pre-operative setting were ‘three’ and ‘four-or-more’ (27.8% and 25.1%, respectively). Medical oncologists had a significantly higher tendency to offer chemotherapy between radiation therapy and surgery compared to the other groups. Optimal time of surgery was different between groups, but there was no difference among groups between surgery and the ‘watch & wait’ strategy. Neoadjuvant chemotherapy regimens were significantly different between groups. Conclusions: We found that the new pre-operative chemotherapy regimen with short-course radiotherapy was slowly adopted into current practice. Also, medical oncologists tended to prefer pre-operative chemotherapy in comparison to the other groups.

Total Neoadjuvant Therapy for Rectal Cancer in the CAO/ARO/AIO-12 Randomized Phase 2 Trial: Early Surrogate Endpoints Revisited

Background: Early efficacy outcome measures in rectal cancer after total neoadjuvant treatment are increasingly investigated. We examined the prognostic role of pathological complete response (pCR), tumor regression grading (TRG) and neoadjuvant rectal (NAR) score for disease-free survival (DFS) in patients with rectal carcinoma treated within the CAO/ARO/AIO-12 randomized phase 2 trial. Methods: Distribution of pCR, TRG and NAR score was analyzed using the Pearson’s chi-squared test. Univariable analyses were performed using the log-rank test, stratified by treatment arm. Discrimination ability of non-pCR for DFS was assessed by analyzing the ROC curve as a function of time. Results: Of the 311 patients enrolled, 306 patients were evaluable (Arm A:156, Arm B:150). After a median follow-up of 43 months, the 3-year DFS was 73% in both groups (HR, 0.95, 95% CI, 0.63–1.45, p = 0.82). pCR tended to be higher in Arm B (17% vs. 25%, p = 0.086). In both treatment arms, pCR, TRG and NAR were significant prognostic factors for DFS, whereas survival in subgroups defined by pCR, TRG or NAR did not significantly differ between the treatment arms. The discrimination ability of non-pCR for DFS remained constant over time (C-Index 0.58) but was slightly better in Arm B (0.61 vs. 0.56). Conclusion: Although pCR, TRG and NAR were strong prognostic factors for DFS in the CAO/ARO/AIO-12 trial, their value in selecting one TNT approach over another could not be confirmed. Hence, the conclusion of a long-term survival benefit of one treatment arm based on early surrogate endpoints should be stated with caution.

Complete response and survival outcomes in patients with advanced cancer on immune checkpoint inhibitors

Aim: To evaluate overall survival in advanced cancer patients who achieved complete response (CR) with immune checkpoint inhibitor (ICI) therapy. Methods: This retrospective study included patients with advanced unresectable or metastatic cancer who received at least one cycle of palliative-intent ICI. Best overall response was used to define response groups. Results: 21 (7%) of 322 patients achieved CR. Multivariate analysis demonstrated that CR was independently associated with better overall survival compared with disease progression (hazard ratio: 0.012; 95% CI: 0.002-0.090) and stable disease (hazard ratio: 0.063; 95% CI: 0.009-0.464) as well as a nonsignificant trend toward better overall survival compared with partial response (hazard ratio: 0.169; 95% CI: 0.023-1.252) regardless of cancer type, ICI regimen or ICI line. Conclusion: Patients who achieved CR had longer survival compared with patients who did not achieve CR.

The Prognostic Importance of ctDNA in Rectal Cancer: A Critical Reappraisal

Simple Summary

An individualized treatment approach is necessary to improve survival and quality of life in rectal cancer. Tools to stratify patients are missing, but ctDNA seems to be a good candidate. Current results are sparse, conflicting and characterized by lack of a uniform approach. As the interpretation of results is dependent on the quality of reporting, we aimed to address this issue in our paper. Our results indicate an association between ctDNA status and outcome. In six out of nine papers, bias was low. However, a conclusion is dubious because of the heterogeneity among the studies and lack of standardized methods. Studies addressing these issues are warranted.

Abstract

The treatment of locally advanced rectal cancer (LARC) has evolved during the last decades, but recurrence remains a problem. Circulating tumor DNA (ctDNA) may result in an individualized treatment approach with improved survival and quality of life, but diverging results impede further development. In this systematic review, we addressed the quality of reporting and its impact on the interpretation of ctDNA results. We performed a systematic literature search using subject headings and search terms related to ctDNA and rectal cancer. The Quality of Prognostic Studies (QUIPS) tool was used to assess bias. Nine studies, with substantial heterogeneity, were included in the analysis. Three out of nine articles had moderate or high risk of bias. No association was found between treatment response and ctDNA status at baseline. There was a negative association between ctDNA positivity at baseline, before and after surgery and survival. The ctDNA status may be of importance to the long-term prognosis, but the area of research is new and is short of dedicated studies. There is an obvious need for standardization in ctDNA research, and the issue should be addressed in future research.

Identifying the long-term survival beneficiary of preoperative radiotherapy for rectal cancer in the TME era

This study was to verify the long-term survival efficacy of preoperative radiotherapy (preRT) for locally advanced rectal cancer (LARC) patients and identify potential long-term survival beneficiary. Using the Surveillance, Epidemiology, and End Results (SEER) database, 7582 LARC patients were eligible for this study between 2011 and 2015 including 6066 received preRT and 1516 received surgery alone. Initial results showed that preRT prolonged the median overall survival (OS) of LARC patients (HR 0.86, 95% CI 0.75-0.98, P < 0.05), and subgroup analysis revealed that patients with age > 65 years, stage III, T3, T4, N2, tumor size > 5 cm, tumor deposits, and lymph nodes dissection (LND) ≥ 12 would benefit more from preRT (all P < 0.05). A prognostic predicting nomogram was constructed using the independent risk factors of OS identified by multivariate Cox analysis (all P < 0.05), which exhibited better prediction of OS than the 8th American Joint Cancer Committee staging system on colorectal cancer. According to the current nomogram, patients in the high-risk subgroup had a shorter median OS than low-risk subgroup (HR 2.62, 95% CI 2.25-3.04, P < 0.001), and preRT could benefit more high-risk patients rather than low-risk patients. Hence, we concluded that preRT might bring long-term survival benefits to LARC patients, especially those with high risk.

Surrogate endpoints for early-stage breast cancer: a review of the state of the art, controversies, and future prospects

Drug approval for early-stage breast cancer (EBC) has been historically granted in the context of registration trials based on adequate outcomes such as disease-free survival and overall survival. Improvements in long-term outcomes have made it more difficult to demonstrate the clinical benefit of a new cancer drug in large, randomized, comparative clinical trials. Therefore, the use of surrogate endpoints rather than traditional measures allows for cancer drug trials to proceed with smaller sample sizes and shorter follow-up periods, which reduces drug development time. Among surrogate endpoints for breast cancer, the increase in pathological complete response (pCR) rates was considered appropriate for accelerated drug approval. The association between pCR and long-term outcomes was strongest in patients with aggressive tumor subtypes, such as triple-negative and human epidermal growth factor receptor 2 (HER2)-positive/hormone receptor-negative breast cancers. Whereas in hormone receptor-positive/HER2-negative EBC, the most accepted surrogate markers for endocrine therapy-based trials include changes in Ki67 and the preoperative endocrine prognostic index. Beyond the classic endpoints, further prognostic tools are required to provide EBC patients with individualized and effective therapies, and the neoadjuvant setting provides an excellent platform for drug development and biomarker discovery. Nowadays, the availability of multigene signatures is offering a standardized quantitative and reproducible tool to potentiate the efficacy of standard treatment for high-risk patients and develop de-escalated treatments for patients at lower risk of relapse. In this article, we first evaluate the surrogacies used for long-term outcomes and the underlying evidence supporting the use of each surrogate endpoint for the accelerated or regular drug approval process in EBC. Next, we provide an overview of the most recent studies and innovative strategies in a (neo)adjuvant setting as a platform to accelerate new drug approval. Finally, we highlight some clinical trials aimed at tailoring systemic treatment of EBC using prognosis-related factors or early biomarkers of drug sensitivity or resistance.

Biomarkers in Locally Advanced Rectal Cancer: A Review

Locally advanced rectal cancers (LARC) are the subject of a rapidly evolving treatment paradigm. The critical timepoints where management decisions are required during the care of the LARC patient are: prior to the institution of any treatment, post neoadjuvant therapy and post-surgery. This article reviews the clinical, imaging, blood-based, tissue-based, and molecular biomarkers that can assist clinicians at these timepoints in the patient's management, in prognosticating for their LARC patients or in predicting responses to therapy in the multi-modality neoadjuvant treatment era.

Survival landscape of different tumor regression grades and pathologic complete response in rectal cancer after neoadjuvant therapy based on reconstructed individual patient data

BACKGROUND

Neoadjuvant therapy can lead to different tumor regression grades (TRG) in rectal cancer after neoadjuvant therapy. The purposes of this study are to investigate the relationships among TRG, pathologic complete response (pCR) and long-term survival, on the basis of reconstructed individual patient data (IPD).

METHODS

The PubMed, Embase, Ovid and Cochrane CENTRAL databases were searched. The primary endpoint was to evaluate the survival landscape of different TRGs after neoadjuvant therapy and the secondary endpoint was to evaluate the associations between pCR and survival. IPD were reconstructed with Kaplan-Meier curves.

RESULTS

The 10-year overall survival (OS) and 5-year disease-free survival (DFS) were clearly higher in the pCR group than in the non-pCR (npCR) group (80.5% vs. 48.3, 90.1% vs. 69.8%). Furthermore, the OS and DFS increased with improvement in tumor regression after neoadjuvant therapy. According to the IPD, the pCR group had longer OS (HR = 0.240, 95% CI = 0.177-0.325, p < 0.001) and DFS (HR = 0.274, 95% CI = 0.205-0.367, p < 0.001) than the npCR group. Better tumor regression was associated with better survival outcomes (p < 0.005). Direct calculation of published HR values yielded similar results.

CONCLUSIONS

Our results indicate a positive relationship between better tumor regressions and improved survival benefits among the npCR group and patients with rectal cancer achieving pCR had much longer OS and DFS than patients achieving npCR, presenting a survival landscape of different TRGs and pCR in rectal cancer after neoadjuvant therapy.

Surrogate Endpoints in Oncology: Overview of Systematic Reviews and Their Use for Health Decision Making in Mexico

OBJECTIVES

The use of surrogate endpoints (SEs) for cancer drug approval in health systems is common. The objectives of this study were to identify systematic reviews (SRs) that evaluated the correlation of SEs with overall survival (OS) in cancer drugs to analyze the applications of approved cancer drugs with SEs in Mexico and to apply the validation framework proposed by the Institute for Quality and Efficiency in Health Care (IQWiG).

METHODS

An overview of SRs was conducted according to Cochrane Collaboration methodology. Applications for approved cancer drugs with SEs in Mexico were analyzed. The IQWiG validation framework was applied to evaluate the SEs identified in the overview and in the applications in Mexico.

RESULTS

A total of 85 SRs that assessed 192 SEs for different types of cancer were selected. According to the IQWiG model, only 2.5% of the SEs analyzed in the overview and only one of the applications in Mexico could be used as surrogates for OS because the reliability (methodological quality) of the SRs and the strength of the correlation of SEs with OS was mostly low (92%) and low (correlation coefficient r ≤ 0.7; 50.5%), respectively. Of the total number of cancer drugs approved in Mexico, 19.4% used SEs.

CONCLUSIONS

Most SEs for different types of cancer could not be used as surrogates for OS according to the IQWiG model, and their use for the approval of cancer drugs in Mexico is generally not justified.

Improved response rate in patients with prognostically poor locally advanced rectal cancer after treatment with induction chemotherapy and chemoradiotherapy when compared with chemoradiotherapy alone: A matched case-control study

INTRODUCTION

The addition of induction chemotherapy (ICT) to neoadjuvant chemoradiotherapy (CRT) has the potential to improve outcomes in patients with locally advanced rectal cancer (LARC). However, patient selection is essential to prevent overtreatment. This study compared the complete response (CR) rate after treatment with and without ICT of LARC patients with prognostically poor characteristics.

METHODS

All LARC patients who were treated with neoadjuvant CRT, whether or not preceded by ICT, and who underwent surgery or were considered for a wait-and-see strategy between January 2016 and March 2020 in the Catharina Hospital Eindhoven, were retrospectively selected. LARC was defined as any T4 tumour, or a T2/T3 tumour with extramural venous invasion and/or tumour deposits and/or N2 lymph node status, and/or mesorectal fascia involvement (T3 tumours only). Case-control matching was performed based on the aforementioned characteristics.

RESULTS

Of 242 patients, 178 (74%) received CRT (CRT-group) and 64 patients (26%) received ICT followed by CRT (ICT-group). In the ICT-group, 3 patients (5%) did not receive the minimum of three cycles. In addition, in this selected cohort, compliance with radiotherapy was 100% in the ICT-group and 97% in the CRT-group. The CR rate was 30% in the ICT-group and 15% in the CRT-group (p = 0.011). After case-control matching, the CR rate was 28% and 9%, respectively (p = 0.013).

CONCLUSION

Treatment including ICT seemed well tolerated and resulted in a high CR rate. Hence, this treatment strategy may facilitate organ preservation and improve survival in LARC patients with prognostically poor characteristics.

Complete pathological response in rectal cancer utilising novel treatment strategies for neo-adjuvant therapy: A systematic review

BACKGROUND

Locally advanced rectal cancer is routinely treated with neo-adjuvant long course chemoradiotherapy or short course radiotherapy, followed by total mesorectal excision. Not all patients respond to this treatment and there has been an emergence of novel treatment strategies designed to improve outcomes for these patients. This systematic review aims to assess the current novel neo-adjuvant treatment strategies being utilised in the treatment of patients with rectal cancer and how these impact pathological complete response (pCR) rates.

METHODS

A systematic review of the literature was performed to evaluate pathological response in patients with rectal cancer receiving novel neo-adjuvant therapy. EMBASE and Medline electronic databases were searched for relevant articles. Articles published between January 2008 and February 2019 were retrieved. Included studies underwent critical appraisal and complete pathological response rates were recorded.

RESULTS

Of the initial 1074 articles identified, 217 articles fulfilled the inclusion criteria, of these 60 articles (4359 patients) were included. Neo-adjuvant therapy delivered included novel long course chemoradiation therapy, neoadjuvant chemotherapy alone, addition of a biological agent, total neo-adjuvant therapy, novel short course radiation therapy and studies utilising biomarkers to select patients for therapy. Complete pathological response rates ranged from 0 to 60%.

CONCLUSION

A validated novel neo-adjuvant therapy that significantly increases pCR rates in patients with rectal cancer has not been identified.

Curative therapy for rectal cancer

Introduction: A comprehensive trimodality approach has become the standard of care for patients with locally advanced rectal cancer. However, the sequencing and duration of chemotherapy and chemoradiotherapy around surgery varies between clinical studies and geographical regions. Growing evidence is also mounting for strategies such as total neoadjuvant therapy and non-operative management for carefully selected patients.Areas covered: We provide a perspective review of the current evidence and controversies in the treatment of locally advanced rectal cancer including the recent updates from the 2020 ASCO annual conference.Expert opinion: With ongoing advances in the management of locally advanced rectal cancer, a multidisciplinary team approach is necessary as treatments could involve multiple approaches. Chemoradiotherapy whether short or long course followed by at least 3 months of systemic chemotherapy may be the preferred option to balance local and distant disease control. Albeit the choice of doublet or triplet chemotherapy is still controversial. As total neoadjuvant treatment becomes part of the standard of care in rectal cancer, modification of the surveillance schedule is needed to detect early recurrences which may be limited by resources and availability of services.

Outcome measures in multimodal rectal cancer trials

There is a large variability regarding the definition and choice of primary endpoints in phase 2 and phase 3 multimodal rectal cancer trials, resulting in inconsistency and difficulty of data interpretation. Also, surrogate properties of early and intermediate endpoints have not been systematically assessed. We provide a comprehensive review of clinical and surrogate endpoints used in trials for non-metastatic rectal cancer. The applicability, advantages, and disadvantages of these endpoints are summarised, with recommendations on clinical endpoints for the different phase trials, including limited surgery or non-operative management for organ preservation. We discuss how early and intermediate endpoints, including patient-reported outcomes and involvement of patients in decision making, can be used to guide trial design and facilitate consistency in reporting trial results in rectal cancer.

Total Neoadjuvant Therapy in Rectal Cancer: A Systematic Review and Meta-analysis of Treatment Outcomes

BACKGROUND

The addition of induction chemotherapy to concomitant neoadjuvant chemoradiation in locally advanced rectal cancer could increase pathological downstaging and act on occult micrometastatic disease, leading ultimately to a better outcome. A systematic review was carried out of the existing literature on the treatment outcomes of total neoadjuvant therapy (TNT) on locally advanced rectal cancer. TNT was defined as chemotherapy using cycles of induction and/or consolidation in conjunction with standard chemoradiotherapy prior to surgery.

METHODS

A systematic search of PubMed, Embase, and the Cochrane Library was performed according to the PRISMA statement up until January 2019. The primary endpoints were complete pathologic response (pCR), disease-free survival, and overall survival rates.

RESULTS

A total of 28 studies (3 retrospective and 25 prospective for a total of 3579 patients) were included in the final analysis (n = 2688 treated with TNT and n = 891 with neoadjuvant chemoradiotherapy therapy). The pooled pCR rate was 22.4% (95% CI 19.4%-25.7%) in all patients treated with TNT (n = 27 studies with data available). In n = 10 comparative studies with data available, TNT was found to increase the odds of pCR by 39% (1.40, 95% CI 1.08-1.81, P = 0.01).

CONCLUSIONS

The addition of induction or consolidation chemotherapy to standard neoadjuvant chemoradiotherapy results in a higher pCR rate. Given that the comparative analysis was derived from few randomized publications, large confirmatory trials should be carried out before a strong recommendation is made in favor of TNT.

Pathologic Complete Response Despite Nodal Yield Has Best Survival in Locally Advanced Rectal Cancer

BACKGROUND

Controversy exists regarding the ability of neoadjuvant chemoradiation (nCR) to diminish lymph node yield (LNY) and how that relationship is influenced by tumor response in patients undergoing proctectomy for locally advanced rectal cancer.

MATERIALS AND METHODS

The National Cancer Database was used to identify patients with rectal adenocarcinomas from 2004 to 2014. Patients that received nCR were compared with those that underwent surgery alone. LNY was stratified into <12 and ≥12 groups to determine their differences in stage specific overall survival.

RESULTS

Of 56,812 patients 46.5% underwent surgery alone and 53.5% were administered nCR. There were more patients with LNY<12 in the nCR group compared to surgery alone, across all stages (44.1% versus 36.5%, P < 0.001). nCR improved OS regardless of LNY (P < 0.001). Although patients with LNY≥12 had improved overall survival, patients who had a pathologic complete response (pCR) achieved the greatest survival. In patients that did not achieve a pCR, LNY≥12 was a marker of improved OS but LNY did not impact OS in patients that attained pCR (P < 0.001).

CONCLUSIONS

Although nCR diminished LNY, LNY≥12 improved OS demonstrating the importance of quality total mesorectal excision. However, LNY did not impact patients that achieved pCR. These patients, who achieved the best OS, demonstrated that tumors' biologic response to nCR had the greatest impact on patient outcomes.

Characteristic and outcomes of patients with pathologic complete response after preoperative treatment in borderline and locally advanced pancreatic adenocarcinoma: An AGEO multicentric retrospective cohort

INTRODUCTION

Following publication of improved patients' outcome using first line FOLFIRINOX for metastatic pancreatic adenocarcinoma, many physicians now prescribe it as neo-adjuvant or induction treatment for borderline and locally advanced pancreatic cancer. A pathologic complete response, rarely seen with previous preoperative regimens, is sometimes observed in these patients. The aim of this study was to assess long-term outcomes of patients presenting pathologic complete response after preoperative FOLFIRINOX usually followed by chemo-radiation therapy for non-metastatic pancreatic adenocarcinoma.

MATERIAL AND METHODS

We retrospectively identified all resected patients with pancreatic cancer presenting pathologic complete response after FOLFIRINOX in 9 French centers from the AGEO group between November 2010 and May 2017.

RESULTS

29 patients were enrolled, 14 had borderline, 14 locally advanced and 1 oligo-metastatic pancreatic cancer. M/F ratio was 1.2 and the mean age was 57 years. All patients were treated with FOLFIRINOX (n = 29), de-escalated to gemcitabine (n = 1) and FOLFIRI (n = 2), and 24 (83 %) received radiation therapy after chemotherapy. Objective response rate to preoperative chemotherapy was 66% (RECIST V1.1). Only 8 patients received postoperative chemotherapy. After a median follow-up of 34 months from surgery, the median overall survival was not reached and the median disease free survival was 48 months. The 1-year and 2-year survival rates were 100% for OS and 96% and 72 % for DFS from surgery, 8 of the 9 observed recurrences were distant metastases.

CONCLUSIONS

The promising 1 and 2-year overall survival and disease free survival rates suggest that pathologic complete response is a major prognostic factor in resected pancreatic cancer following preoperative chemo-radiotherapy. A longer follow-up and prospective series are now necessary to confirm these encouraging results and to potentially validate pathologic complete response as a relevant surrogate marker of preoperative treatment efficacy.

The survival benefit of intensified full-dose XELOX chemotherapy concomitant to radiotherapy and then resting-period consolidation chemotherapy in locally advanced rectal cancer

Purpose: To evaluate the effect of an intensified capecitabine and oxaliplatin (XELOX) chemoradiation treatment followed by one cycle of consolidation chemotherapy before surgery in locally advanced rectal cancer (LARC).

Methods and Materials: Patients with histologically confirmed, newly diagnosed, locally advanced rectal adenocarcinoma (cT3-T4 and/or cN+) were enrolled. All patients received 3-dimensional conformal radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT) with a dose 50.4Gy in 25 fraction, with two cycles of concurrent XELOX chemotherapy. Thereafter, another cycle of consolidation chemotherapy with XELOX/FLOFOX was administered during the resting period after completion of concurrent chemoradiation (CRT). Tumor response, toxicities, surgical complications, and long-term clinical outcomes were recorded.

Results: From January 2011 to December 2013, a total of 96 patients were enrolled in the study. All patients completed the treatment plan of concurrent chemoradiation and consolidate chemotherapy. During concurrent chemoradiation, the incidence of grade 3/4 toxicities was leucopenia (2.1%), thrombocytopenia (4.2%), diarrhea (6.3%). 18 patients (18.8%) developed surgical complications. Pathologic complete response (pCR) was achieved in 20 (20.8%) patients. Tumor down-staging occurred in 69 (71.9%) patients and down-staging of nodes occurred in 47 (49.0%) patients. Of these 96 patients, 5-year local recurrence-free survival, metastasis-free survival, disease-free survival and overall survival rates was 98.9%, 84.7%, 83.7% and 82.1%, respectively, with a median follow-up of 4.24years.

Conclusions: The intensified treatment paradigm of XELOX concurrent chemoradiation followed by one cycle of consolidation chemotherapy was well tolerated in our cohort and provided a promising long-term oncologic outcome, which warranted further investigation in a randomize trails.

Neoadjuvant hyperfractionated accelerated radiotherapy plus concomitant 5-fluorouracil infusion in locally advanced rectal cancer: A phase II study

AIM

To evaluate the efficacy and tolerability of neoadjuvant hyperfractionated accelerated radiotherapy (HART) and concurrent chemotherapy in patients with locally advanced infraperitoneal rectal cancer.

METHODS

A total of 30 patients with histopathologically confirmed T2-3/N0+ infraperitoneal adenocarcinoma of rectum cancer patients received preoperative 42 Gy/1.5 Gy/18 days/bid radiotherapy and continuous infusion of 5-fluorouracil (325 mg/m2). All patients were operated 4-8 wk after neoadjuvant concomitant therapy.

RESULTS

In the early phase of treatment, 6 patients had grade III-IV gastrointestinal toxicity, 2 patients had grade III-IV hematologic toxicity, and 1 patient had grade V toxicity due to postoperative sepsis during chemotherapy. Only 1 patient had radiotherapy-related late side effects, i.e., grade IV tenesmus. Complete pathological response was achieved in 6 patients (21%), while near-complete pathological response was obtained in 9 (31%). After a median follow-up period of 60 mo, the local tumor control rate was 96.6%. In 13 patients, distant metastasis occurred. Disease-free survival rates at 2 and 5 years were 63.3% and 53%, and corresponding overall survival rates were 70% and 53.1%, respectively.

CONCLUSION

Although it has excellent local control and complete pathological response rates, neoadjuvant HART concurrent chemotherapy appears to not be a feasible treatment regimen in locally advanced rectal cancer, having high perioperative complication and intolerable side effects. Effects of reduced 5-fluorouracil dose or omission of chemotherapy with the aim of reducing toxicity may be examined in further studies.