Melanoma and microbiota: Current understanding and future directions

Over the last decade, the composition of the gut microbiota has been found to correlate with the outcomes of cancer patients treated with immunotherapy. Accumulating evidence points to the various mechanisms by which intestinal bacteria act on distal tumors and how to harness this complex ecosystem to circumvent primary resistance to immune checkpoint inhibitors. Here, we review the state of the microbiota field in the context of melanoma, the recent breakthroughs in defining microbial modes of action, and how to modulate the microbiota to enhance response to cancer immunotherapy. The host-microbe interaction may be deciphered by the use of "omics" technologies, and will guide patient stratification and the development of microbiota-centered interventions. Efforts needed to advance the field and current gaps of knowledge are also discussed.

The role of total neoadjuvant therapy in locally advanced rectal cancer: a survey of specialists attending the All-Ireland Colorectal Cancer Conference 2022 including lead investigators of OPRA, PRODIGE-23 and RAPIDO

BACKGROUND

The treatment of locally advanced rectal cancer (LARC) has evolved following recent landmark trials of total neoadjuvant therapy (TNT)-the delivery of preoperative chemotherapy sequenced with radiation.

AIM

To assess the preferences of colorectal surgery (CRS), radiation oncology (RO) and medical oncology (MO) specialists attending the All-Ireland Colorectal Cancer Conference (AICCC) 2022 regarding the neoadjuvant management of LARC.

METHODS

A live electronic survey explored the preferred treatment approach and TNT regimen for early-, intermediate-, bad-, and advanced-risk categories of rectal cancer according to the European Society of Medical Oncology (ESMO) guidelines. The survey was preceded by an update from lead investigators of TNT trials (OPRA, PRODIGE-23 and RAPIDO), who then participated in a multidisciplinary panel discussion.

RESULTS

Ten CRS, 7 RO and 15 MO (32 of 45 specialists) participated fully in the survey resulting in a response rate of 71%. Ninety-four percent, 76% and 53% of specialists preferred a TNT approach for patients with advanced, bad, and intermediate-risk rectal cancer, respectively. A consolidation TNT regimen of long-course chemoradiotherapy followed by chemotherapy was the most preferred regimen. Upfront surgery was preferred by 77% for early-risk disease.

CONCLUSION

This survey illustrated the general acceptance of TNT by rectal cancer specialists attending the AICCC as a valuable treatment strategy for higher-risk category LARC. Whilst the treatment of LARC changes, it remains best practice to individualize care, incorporating the selective use of TNT as discussed by an MDT and in keeping with the patient's goals of care.

Survival data of PRADO: A phase 2 study of personalized response-driven surgery and adjuvant therapy after neoadjuvant ipilimumab (IPI) and nivolumab (NIVO) in resectable stage III melanoma

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Background: In the OpACIN-neo study, 2 cycles neoadjuvant (neoadj) IPI 1mg/kg + NIVO 3mg/kg (I1N3) have been identified as most favorable dosing scheme with a pathologic response rate (pRR) of 77% and 20% grade 3-4 irAEs. After 24.6 months median follow-up (FU), the 2-year (2y) RFS was 96.9% for patients (pts) with pathologic response versus 35.5% for non-responders (>50% viable tumor; pNR). These data raised the question whether therapeutic lymph node dissection (TLND) could be safely omitted in pts achieving a major pathologic response (MPR; ≤10% viable tumor) in their index node (ILN; largest LN metastasis at baseline), and if additional adjuvant (adj) therapy could improve the outcome of pNR pts. Methods: PRADO is an extension cohort of the phase 2 OpACIN-neo study aiming to confirm the pRR and safety of neoadj I1N3 and to test response-driven subsequent therapy. Pts with stage III melanoma were included to receive 2 cycles neoadj I1N3 after marker placement in the ILN. ILN resection was planned at week 6. Pts that achieved MPR in the ILN did not undergo TLND; pts with partial response (pPR; >10 – ≤50% viable tumor) underwent TLND; and pts with pNR underwent TLND and received adj NIVO or dabrafenib plus trametinib (D+T) for 52 weeks ±radiotherapy (RT). Primary endpoints were pRR in the ILN and RFS at 2y. The 2y RFS rates were calculated using a Kaplan Meier based method. Results: Between Nov 2018 and Jan 2020, 99 patients were enrolled and treated with at least 1 cycle of neoadj I1N3. We previously showed a pRR of 72% (95% CI 62 - 80), including 60 (61%) pts with MPR and 11 (11%) pts with pPR. TLND omission in MPR pts resulted in significant reduced surgical morbidity and improved quality of life. There were 27 non-responders of whom 6 developed distant metastasis before ILN resection. Of the other 21 pNR pts, 7 received adj NIVO, 10 adj D+T, 3 no adj therapy, and 1 was lost to FU. After a median FU of 27.9 months (data cutoff Jan 31, 2022), the estimated 2y RFS rate for MPR pts was 93.3% (95% CI 87.2 – 99.9), with 4/60 pts developing a regional relapse. Distant metastasis-free survival (DMFS) was 100%. Of the 11 pPR pts, 4 developed a relapse (all distant), resulting in a 2y RFS and DMFS rate of 63.6% (95% CI 40.7 – 99.5). The 2y RFS rate of the pNR pts was 71.4% (95% CI 54.5 – 93.6), and DMFS 76.2%. At data cutoff, relapse occurred in 2/7 pNR pts with adj NIVO and 3/10 with adj D+T. Final data cutoff is planned mid Feb, 2022. Conclusions: MPR pts in whom TLND was omitted showed a 2y RFS rate of 93.3% and DMFS of 100%, indicating that the ILN procedure and omitting adj therapy could become a safe approach in these pts. Adj systemic therapy in pNR pts seems to improve RFS as compared to historic control (OpACIN-neo), thus should be considered in this unfavorable pNR group. The DMFS rate of 63.6% observed in the pPR group advocates the consideration of adj therapy also for this subgroup in the future. Clinical trial information: NCT02977052.

Adjuvant treatment of in-transit melanoma: Addressing the knowledge gap left by clinical trials

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Background: Few clinical trials address the efficacy of adjuvant systemic treatment in patients with ITM. This study describes the efficacy of adjuvant systemic therapy of ITM patients beyond the clinical trial setting. Methods: All stage III adjuvant-treated melanoma patients registered in the nationwide Dutch Melanoma Treatment Registry between 01-07-2018 and 31-12-2020 were included. Patients were divided into three groups: patients with ITM only, with ITM and nodal disease, and patients with nodal disease only. Differences in recurrence patterns were analysed. An exploratory analysis was performed for stage III patients who underwent surgical resection without adjuvant treatment. Recurrence-free survival (RFS) and overall survival (OS) at 12-months were assessed. Results: A total of 1037 stage III melanoma patients received adjuvant anti-PD-1 therapy, and 260 underwent surgical resection only. Of the adjuvant-treated patients, 16.9% had ITM only, 15.5% had ITM with nodal disease, and 66.8% had nodal disease only. Of the surgical resection only patients 20.4% had ITM only, 12.3% had ITM with nodal disease and 67.3% had nodal disease only. In the adjuvant-treated patients, 12-months RFS was comparable between patients with ITM only and patients with nodal disease only (71.1% vs. 72.2% respectively, p = 0.95), but significantly lower for patients with ITM and nodal disease (57.1%; ITM with nodal disease vs. ITM-only p = 0.01, and ITM with nodal disease vs. nodal disease only p < 0.01). Locoregional metastases occurred as first recurrence site in 72.7% of ITM-only patients, 42.9% of ITM and nodal disease patients and 38.9% of patients with nodal disease only, while distant recurrences occurred in 18.2% of patients with ITM only, in 36.7% of patients with ITM and nodal disease, and in 42.3% of patients with nodal disease only (p = 0.01). OS at 12-months was significantly higher for ITM-only patients compared to patients with ITM and nodal disease (97.7% vs. 90.6%, p < 0.01), and was better compared to patients with nodal disease only (97.7% vs. 94.4%, p = 0.05). OS at 12-months was comparable for patients with ITM and nodal disease and patients with nodal disease only (p = 0.19). In general, surgery-only ITM patients were older and had a worse performance score. 12-months RFS appeared worse compared to adjuvant-treated ITM patients (36.6% vs. 68.3%). In this group of surgery-only ITM patients OS at 12-months also appeared worse compared to adjuvant-treated ITM patients (89.7% vs. 95.5%). Conclusions: RFS rates in ITM-only patients are similar to non-ITM patients, while RFS in patients with ITM and nodal disease is shorter. Adjuvant-treated patients with ITM without nodal disease less often experience distant recurrences and have a superior OS compared to other adjuvant stage III patients. Our results suggest that other treatment strategies for ITM patients with nodal disease should be considered.

Management of checkpoint inhibitor toxicity and survival in patients with advanced melanoma

9546

Background: Management of checkpoint-inhibitor-induced immune-related adverse events (irAEs) is primarily based on expert opinion. Recent studies have suggested detrimental effects of immunosuppressive treatment with anti-TNF on checkpoint-inhibitor efficacy. Methods: Advanced melanoma patients experiencing grade ≥3 irAEs after treatment with first-line ipilimumab-nivolumab between 2015 and 2021 were included from the Dutch Melanoma Treatment Registry. Progression-free survival (PFS), overall survival (OS) and melanoma-specific survival (MSS) were analyzed according to toxicity management regimen. A cox proportional hazards model was used to account for the confounders age, sex, performance status, lactate dehydrogenase, site of metastases and type of irAE. Results: Out of 771 ipilimumab-nivolumab treated patients, 350 were treated with immunosuppression for severe irAEs. Of these patients, 235 received steroids only and 115 received steroids with second-line immunosuppressants consisting of anti-TNF, mycophenolic acid, tacrolimus and other immunosuppressants. Median PFS was significantly longer for patients treated with steroids (11.3 months) than for patients treated with steroids and second-line immunosuppressants (5.4 months; HR 1.43; 95%CI 1.07-1.90; p = 0.01). Median OS was also significantly longer for the steroids group (46.1 months) than for the steroids and second-line immunosuppressants group (22.5 months; HR 1.64; 95%CI 1.16-2.32; p = 0.005). Results for MSS were similar (not reached versus 28.8 months; HR 1.70; 95%CI 1.16-2.49; p = 0.006). Median PFS, OS and MSS are shown in Table 1. After adjustment for potential confounders, patients treated with steroids + second-line immunosuppressants showed a non-significant trend towards a higher risk of progression (HRadj 1.40; 95%CI 1.00-1.97; p = 0.05), a higher risk of death (HRadj 1.54; 95%CI 1.03-2.30; p = 0.04) and of melanoma-specific death (HRadj 1.62; 95%CI 1.04-2.51; p = 0.032) compared to the steroids group. Conclusions: Second-line immunosuppression for irAEs is associated with impaired PFS, OS, and MSS in advanced melanoma patients treated with first-line ipilimumab-nivolumab, irrespective of being anti-TNF or other second-line immunosuppressants. These findings stress the importance of assessing the effects of differential irAE management strategies, not only in melanoma but also in other tumor types. [Table: see text]

Hospital variation in cancer treatments and survival outcomes of advanced melanoma patients: Nationwide quality assurance in the Netherlands

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Background: The introduction of new systemic treatments for advanced melanoma has markedly changed the outcome of patients with metastatic melanoma. To assure high quality of care for patients treated in Dutch melanoma centers, hospital variation in treatment patterns and outcomes are evaluated in the Dutch Melanoma Treatment Registry. The aim of this study was to assess center variation in treatments and 2-year survival probabilities of patients diagnosed between 2013-2017 in the Netherlands. Methods: We selected patients diagnosed between 2013-2017 with unresectable stage IIIC or IV melanoma, registered in the Dutch Melanoma Treatment Registry. Centers’ performance on 2-year survival was compared by means of a multivariable Cox proportional hazards model with a random effect for center ID. Variation between centers was expressed by median hazard ratios. Therapy with BRAF/MEK inhibitors, anti-PD-1 antibodies or ipilimumab plus nivolumab was added to the Cox proportional hazards model as a time dependent covariate to assess the influence of new systemic therapies on center variation. Results: Between 2013-2017, 3820 patients were diagnosed with unresectable stage IIIC or IV melanoma. For patients diagnosed between 2013-2015, significant center variation in 2-year survival probabilities was observed. Median hazard ratio was 1.17 (95%CI: 1.09-1.31) for patients diagnosed between 2013-2015 after correcting for case-mix and treatment with BRAF/MEK inhibitors, anti-PD-1 antibodies or ipilimumab plus nivolumab. Use of new systemic therapies had a significant effect on up to 2-year survival (hazard ratio = 0.83, 95%CI (0.73-0.94)) with no use of the new systemic therapies as a reference. From 2016 onwards, no significant difference in 2-years survival was observed between centers. Conclusions: The different use of new cancer treatment of metastatic melanoma had an effect on survival outcomes in the Netherlands. A platform such as the Dutch Melanoma Treatment Registry, in which melanoma centers collaborate and have insight in variation in treatment patterns and outcomes between centers, results in fast implementation of new clinical developments across all Dutch melanoma centers.

Is adjuvant treatment for melanoma in clinical practice comparable to trials? The first population-based results

e21523

Background: Little is known about the outcome of adjuvant therapy in melanoma patients beyond the clinical trial setting. The Dutch Melanoma treatment Registry (DMTR) is a population-based registry, set up in July 2013 to monitor the safety and quality of melanoma care. Since 2019, adjuvant treated melanoma patients have also been registered in the DMTR, following approval and reimbursement of adjuvant treatment in the Netherlands in December 2018. Methods: Analyses were performed on melanoma patients treated with adjuvant anti-PD1 therapy included in the DMTR between 01-07-2018 and 31-12-2019. Descriptive statistics were used to analyze patient-, and treatment characteristics, and death as well as relapse rates. Results: Six hundred and fifty-seven patients treated with adjuvant systemic therapy were included in the DMTR. The majority (94%) of these patients was treated with anti-PD1. Twenty percent of the anti-PD1-treated patients developed grade ≥3 toxicity. Of the 279 patients with a minimum follow-up of one year after start of anti-PD1, 170 (61%) prematurely discontinued therapy. Relapse and death occurred in respectively, 38% and 12% of patients within one year of follow-up. Relapse was significantly more frequent in older patients, with high Breslow thickness and ulcerated melanomas. Conclusions: These data show more frequent premature discontinuation of adjuvant anti-PD1 in daily clinical practice than reported in the registration trials. Moreover, incidence of severe toxicity, relapse and death during adjuvant treatment appears higher in the real-world setting.

Efficacy of checkpoint inhibition in advanced acral melanoma

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Background: Recent data in Japanese patients suggest poor outcomes for anti-PD1 in acral melanoma (AM), with no data available on combination treatment. The objective of this study was to analyze the efficacy of anti-PD1 monotherapy and anti-PD1 and anti-CTLA4 combination therapy in these patients. Methods: Our study population consisted of patients registered in the nationwide prospective Dutch Melanoma Treatment Registry between 2014 and 2020. We calculated objective response rate (ORR) in all unresectable stage III and IV AM and nonacral cutaneous melanoma (NAM) patients treated with anti-PD1, and combination anti-PD1 and anti-CTLA4. Progression-free survival (PFS), and overall survival (OS) were estimated for first-line treated patients. A Cox proportional hazard analysis was performed to adjust for potential confounders. Results: Nighty-five AM patients received at least one dose of anti-PD1 monotherapy, of whom 58 (61%) as first-line treatment. ORR was 28% (complete response 11%; partial response 18%). Median PFS and OS in patients with first-line treatment were 5.5 months (95% CI 3.5-8.4) and 14 months (95% CI 9.3-25.0). In patients with NAM (n = 1259) ORR was 48% (complete response 18%; partial response 31%). Six-hundred and eighty-eight (55%) patients received anti-PD1 as first-line treatment. Median PFS was 11.7 months (95% CI 9.1-14.9) and median OS was 24 months (95% CI 20.0-29.3) in these patients. Older age, higher ECOG scores, elevated LDH levels, liver metastasis and brain metastasis were significantly associated with lower OS. After adjustment for covariates, acral subtype remained associated with shorter PFS (Hazard Ratio 1.76, 95% CI 1.25-2.48) and OS (Hazard Ratio 1.70, 95% CI 1.17-2.45). Twenty-four AM patients received at least one dose of anti-PD1 plus anti-CTLA4, of which 15 as first-line treatment. ORR was 25% (complete response 4%; partial response 20%). AM patients treated with first-line combination therapy had a median PFS of 3.8 months (95% CI 2.8-NR) and median OS of 7.63 months (95% CI 6.12-NR). ORR in NAM patients treated with combination therapy (n = 599) was 41% (complete response 8%; partial response 33%). Forty-six percent of these patients were treated in the first-line, with a median PFS of 9.7 months (95% CI 6.6-17.1) and median OS of 21.3 months (95% CI 14.6-36.5). Elevated LDH levels and the presence of BRAF mutation were significantly associated with lower OS. No significant association was found between acral subtype and PFS, or OS after adjustment for covariates. Conclusions: This study shows limited efficacy of anti-PD1 for advanced AM, with clinically relevant lower response rates compared to nonacral melanoma types. Although caution is needed because of relatively small numbers and the observational nature of our study, our data confirm limited efficacy of checkpoint inhibition in AM.

BRAF and NRAS mutation status and response to checkpoint inhibition in advanced melanoma

9558

Background: The ability to analyze tumor mutation profiles has altered the oncology treatment landscape over the past decades. However, little is known about the effect of specific gene mutations on the response to immune checkpoint inhibitors (ICIs) in patients with advanced melanoma. Methods: All unresectable stage IIIc and IV patients with BRAF V600, NRAS mutations and BRAF and NRAS wild-type patients treated with anti-PD-1 or ipilimumab-nivolumab between 2012 and 2020 were included from the Dutch Melanoma Treatment Registry, a nationwide population-based registry. Outcomes were objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). A Cox model was used to analyze the association of possible prognostic factors with PFS and OS. Results: In total 1358 first-line patients treated with anti-PD-1 and 524 treated with ipilimumab-nivolumab were included. Median follow-up was 25.6 months for anti-PD-1 treated patients and 16.3 months for ipilimumab-nivolumab treated patients. The highest ORR, in first-line, to anti-PD-1 was in patients who were BRAF and NRAS wildtype (50.2%), compared to BRAF V600 (43.8%) and NRAS mutated patients (49.8%). ORR to ipilimumab-nivolumab was highest in NRAS mutated patients (44.9%), while ORR was 39.5% for BRAF mutated patients and 40.3% for wild-type patients. Median PFS in the anti-PD-1 treatment regimen was significantly higher (p = 0.049) for double wild-type patients (16.7 months) patients than for BRAF mutated patients (9.9 months) and NRAS mutated patients (11.3 months). PFS was not significantly different (p = 0.11) in the ipilimumab-nivolumab treatment cohort, with a median PFS of 6.5 months for the wild-type group, 10.8 months for the BRAF group, and 9.1 months for the NRAS group. In the anti-PD-1 treated patients, median OS was significantly higher (p < 0.001) for BRAF mutated patients (32.8 months) compared to NRAS (21.0 months) and wild-type patients (23.0 months). For ipilimumab-nivolumab treated patients, median OS was also significantly higher (p < 0.001) for BRAF mutated patients (36.5 months) than for NRAS mutated patients (11.8 months) and wild-type patients (16.1 months). After adjustment for potential confounders, the presence of a BRAF mutation remained associated with lower PFS in the anti-PD-1 treatment cohort and better OS in both treatment cohorts. Higher age, higher ECOG score, elevated LDH levels, liver metastases and brain metastases were associated with worse survival. Conclusions: PFS in first-line PD-1 was significantly higher for double wild-type patients than for BRAF mutant and NRAS mutant patients. PFS in ipilimumab-nivolumab treated patients did not significantly differ between BRAF mutant, NRAS mutant and double wild-type patients. OS was significantly higher for BRAF mutant patients in both treatment strata, which is probably the result of the subsequent BRAF/MEK-inhibition treatment option in this group.

Dutch advanced melanoma care in times of COVID-19

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Background: The COVID-19 pandemic COVID had a severe impact on medical care in The Netherlands. So far, few studies have investigated the influence of COVID-19 on advanced melanoma care nationwide. This study aims to investigate the impact of COVID-19 on the systemic treatment of unresectable stage III and IV advanced melanoma patients in the Netherlands. Methods: Data were obtained from the Dutch Melanoma Treatment Registry (DMTR), a population-based nationwide registry of all stage III and IV melanoma patients amenable for systemic treatment. We compared two patient groups dependent on the date of the first diagnosis of metastasis: during the first COVID-19 wave (March 15th 2020 until May 22nd 2020), and a control group during the same period one year earlier. Furthermore, we divided patients into three geographical regions within the Netherlands (north, middle and south). These regions were based on the maximum number of hospital admissions for COVID-19 patients during the first wave, using data from the National Intensive Care Evaluation (NICE). COVID-19 incidence was highest in the southern part of The Netherlands. We investigated baseline characteristics, type of systemic therapy, time from diagnosis of the irresectable stage III or IV melanoma until the start of systemic therapy, postponement of anti-PD-1 courses in patients actively being treated during the predefined time periods and progression-free survival (PFS) and overall survival (OS) using Kaplan-Meier estimates. Results: During the first COVID-19 wave, 104 patients were diagnosed with advanced melanoma versus 166 patients during the control period in 2019. No significant differences were found in patient and tumor characteristics, type of systemic therapies or in the time from diagnosis until the start of systemic therapy, between the different periods. However, during the first wave, the time between diagnosis until the start of treatment was significantly longer in the southern regions as compared to the northern and middle regions (33 vs 9 and 15 days, p-value < 0.05). Anti-PD-1 antibody treatment courses were postponed in 79 patients (15.5%) during the first wave versus four patients (1.1%) in the control period. Significantly more patients had a postponed course in the south during the first wave compared to the middle and northern regions (30.2% vs 2.7% vs 16.7%, p-value < 0.001). With limited follow-up, thus far no significant differences in PFS and OS were found. Conclusions: Advanced melanoma care in the Netherlands was severely affected by the COVID-19 pandemic. In the south, where COVID-19 incidence was highest in the first wave, the start of systemic treatment for advanced melanoma was more often delayed, and treatment courses were more frequently postponed. Longer follow-up is needed to establish whether this has had an impact on patient outcome.

Toxicity, response, and survival in older adults with metastatic melanoma treated with checkpoint inhibitors

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Background: Checkpoint inhibitors have strongly improved survival of patients with metastatic melanoma. Trials suggest no differences in outcomes between older and younger patients, but only relatively young patients with a good performance status were included in these trials. The aim of this study was to describe treatment patterns and outcomes of older adults with metastatic melanoma, and to identify predictors of outcome. Methods: We included all patients aged ≥65 years with metastatic melanoma between 2013 and 2020 from the Dutch Melanoma Treatment registry (DMTR), in which detailed information on patients, treatments and outcomes is available. We assessed predictors of grade ≥3 toxicity and 6-months response using logistic regression models, and melanoma-specific and overall survival using Cox regression models. Additionally, we described reasons for hospital admissions and treatment discontinuation. Results: A total of 2216 patients were included. Grade ≥3 toxicity did not increase with age, comorbidity or WHO performance status, in patients treated with monotherapy (anti-PD1 or ipilimumab) or combination treatment. However, patients aged ≥75 were admitted more frequently and discontinued treatment due to toxicity more often. Six months-response rates were similar to previous randomized trials (40.3% and 43.6% in patients aged 65-75 and ≥75 respectively for anti-PD1 treatment) and were not affected by age or comorbidity. Melanoma-specific survival was not affected by age or comorbidity, but age, comorbidity and WHO performance status were associated with overall survival in multivariate analyses. Conclusions: Toxicity, response and melanoma-specific survival were not associated with age or comorbidity status. Treatment with immunotherapy should therefore not be omitted solely based on age or comorbidity. However, the impact of grade I-II toxicity in older patients deserves further study as older patients discontinue treatment more frequently and receive less treatment cycles.[Table: see text]

Dabrafenib plus trametinib is effective in the treatment of BRAF V600-mutated metastatic melanoma patients: analysis of patients from the dabrafenib plus trametinib Named Patient Program (DESCRIBE II)

In clinical trials, dabrafenib plus trametinib improved overall survival (OS) compared with single-agent BRAF inhibitors (BRAFi) in patients with BRAF V600-mutant unresectable or metastatic melanoma. We investigated dabrafenib plus trametinib therapy in a compassionate-use setting [Named Patient Program (NPP); DESCRIBE II]. A retrospective chart review of patients with BRAF V600-mutated unresectable stage III/IV melanoma receiving dabrafenib plus trametinib as compassionate use was conducted. Treatment patterns and duration, clinical outcomes, and tolerability were evaluated. Of 271 patients, 92.6% had stage IV melanoma, including 36.5% with brain metastases. Overall, 162 patients (59.8%) were BRAFi naive and 171 (63.1%) received first-line dabrafenib plus trametinib. Among BRAFi-naive patients, the overall response rate (ORR) was 67.3%, median OS (mOS) was 20.0 months, and median progression-free survival (mPFS) was 7.5 months. In BRAFi-naive patients with known brain metastases (n = 62), ORR was 61.3%, mOS was 15.5 months, and mPFS was 6.2 months. Eighty-four patients received BRAFi monotherapy for >30 days and switched to dabrafenib plus trametinib prior to progression. Of these 84 patients, 63 had known disease status at the time of switch, and 22 improved with the combination therapy. No new safety signals were identified, and dabrafenib plus trametinib was well tolerated. Dabrafenib plus trametinib showed substantial clinical activity in NPP patients with BRAF V600-mutated unresectable or metastatic melanoma. Analysis of treatment patterns demonstrated the effectiveness of the combination in patients with brain metastases and across lines of therapy with a well tolerated and manageable safety profile.

Real-world outcomes of advanced melanoma patients not represented in phase III trials

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Background: A large proportion of patients with advanced melanoma is not represented in phase III clinical trials, due to ineligibility. Real-world efficacy evidence of immune- and targeted therapies in these patients is lacking. We aimed to provide insight in survival outcomes of systemically treated patients who were not represented in the phase III trials in order to support clinical decision-making. Methods: Systemically treated ineligible patients with advanced melanoma diagnosed between 2014-2017 were analyzed. Prognostic importance of factors associated with overall survival (OS) was assessed by Kaplan Meier method, Cox regression models, predicted OS probabilities of prognostic subgroups and a conditional inference survival (decision) tree. Results: Of 2,536 systemically treated patients with advanced melanoma, 1,004 (40%) patients were ineligible for phase IIII trials. Ineligible patients had a poorer median OS (mOS) compared to eligible patients (8.8 vs 23 months). Eligibility criteria most strongly correlated with survival in ineligible systemically treated patients with ECOG Performance Score (PS) ≥2 vs PS 0-1 (HR 1.95 (95%CI: 1.52-2.5)), symptomatic brain metastases (BM) vs absent BM (HR 1.71 (95%CI: 1.34-2.18)) and LDH > 500 U/l vs normal (HR 1.89 (95%CI: 1.49-2.41)). All other factors for ineligibility were not associated with OS. By combining ECOG PS, BM and LDH, 18 subgroups were created. The 3-year survival probability of patients with ECOG PS ≤1, asymptomatic BM and normal LDH was 35.1%. Patients with ECOG PS of ≥2 with or without symptomatic BM had a mOS of 6.5 and 11.3 months and a 3-year survival probability of 9.3% and 23.6% respectively. In the decision tree, the covariate with the strongest predictive distinctive character for survival was LDH, followed by ECOG PS. Prognosis of LDH of > 500 U/L is infaust, although still long-term survival is possible (3-year survival probability of 15.3%). The decision tree showed the prognosis of patients with symptomatic BM can be good if ECOG PS is 0 and patients are aged ≤55 years (mOS of 22.3 months). Conclusions: Patients with advanced melanoma not represented in phase III trials treated with systemic therapy can achieve long term survival. LDH was the strongest predictive factor associated with survival, followed by ECOG PS and symptomatic BM. Other factors for ineligibility were not associated with OS. These results, together with the decision tree, can be used to provide insight in outcomes to facilitate the shared decision-making process when comparative studies are not available.

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

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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 < 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 .

Surgery for unresectable stage IIIC and IV melanoma in the era of new systemic therapy

10032

Background: Over the past decade opportunities for surgical treatment in metastatic melanoma patients have re-emerged due to the development of novel systemic therapies. However, selecting patients who will benefit from surgery after systemic therapy is still difficult. The aim of this study is to present data on outcomes of surgery in patients with unresectable stage III and IV melanoma, who have previously been treated with immune checkpoint inhibitors (ICI) or targeted therapy, to provide insight in which patients may benefit from surgery. Methods: Data was extracted from the prospectively collected, nationwide, Dutch Melanoma Treatment Registry (DMTR) onunresectable stage IIIC or advanced/metastatic stage IV melanomapatients who obtained disease control with systemic therapy and underwent subsequent surgery. Disease control was defined as a complete response (CR), partial response (PR) or stable disease (SD). After disease control was achieved with systemic therapy, progressive disease (PD) was allowed as a most recent status of disease prior to surgery, to avoid excluding patients with oligoprogression. Major exclusion criteria were non-cutaneous melanoma and brain metastases. Results: Of 3959 patients in the DMTR database, 154 patients met our inclusion criteria. Of these patients, 79 (51%) were treated with ICI, 61 (40%) with targeted therapy and 9.1% with study or other treatments before surgery. The best response to systemic therapy was a CR in 5.2%, PR in 46.1% and SD in 44.2% of patients. At a median follow-up of 10.0 months (IQR 4-22) after surgery, the median overall survival (OS) had not been reached in our cohort and median progression free survival (PFS) was 9.0 months (95% CI 6.3-11.7). A multivariate cox regression analysis showed that when surgery led to CR or PR, the PFS and OS were better than if surgery led to SD or PD (p < 001). Also, ICI seemed to be more favorable than targeted therapy in both PFS (median of 15 versus 7 months) and OS (median not reached versus 32 months) (p = 0.026 and p = 0.003). Conclusions: We conclude that selected unresectable stage IIIC or stage IV melanoma patients might benefit from surgery after achieving disease control with systemic therapy. Expected residual tumor after surgery could be an important selection criterion. Especially patients undergoing surgery after initial tumor response on ICI have a chance of long-term survival.

First safety and efficacy results of PRADO: A phase II study of personalized response-driven surgery and adjuvant therapy after neoadjuvant ipilimumab (IPI) and nivolumab (NIVO) in resectable stage III melanoma

10002

Background: OpACIN-neo tested 3 dosing schemes of neoadjuvant (neoadj) IPI+NIVO and identified 2 cycles of IPI 1mg/kg + NIVO 3mg/kg (I1N3) as the most favorable with a pathologic (path) response rate (pRR) of 77% and 20% grade 3-4 irAEs. After 17.6 months median FU, 1/64 (2%) patients (pts) with path response vs 13/21 (62%) of the non-responders ( > 50% viable tumor cells; pNR) had relapsed. We hypothesized that therapeutic lymph node dissection (TLND) could be omitted in pts achieving a complete or near-complete path response (≤10% viable tumor cells; major path response, MPR) in the index node (largest LN metastasis: ILN), whereas additional adjuvant (adj) therapy might improve the outcome of pNR pts. Methods: PRADO is an extension cohort of the multi-center phase 2 OpACIN-neo study that aims to confirm the pRR and safety of neoadj I1N3 and to test response-driven subsequent therapy. Pts with RECIST 1.1 measurable clinical stage III melanoma were included to receive 2 cycles of neoadj I1N3 after marker placement in the ILN. ILN resection was planned at wk 6. Pts that achieved MPR in the ILN did not undergo TLND; pts with pPR ( > 10 – ≤50% viable tumor cells) underwent TLND; and pts with pNR underwent TLND and received adj NIVO or targeted therapy (TT) for 52 wks +/- radiotherapy (RT). Primary endpoints were pRR in the ILN and 24-month RFS. Estimated toxicity rates at wk 12 were calculated using a Kaplan Meier based method. Results: Between Nov 16, 2018 and Jan 3, 2020, 99 of 114 screened pts were eligible and enrolled. So far, 86 pts had ≥12 wks FU. 70/99 pts achieved a path response in the ILN (pRR 71%, 95% CI 61% - 79%); 60 (61%) had MPR. TLND was omitted in 58 (97%) of the MPR pts. There were 28 non-responders; 7 developed distant metastasis before ILN resection. To date, 8 of the 21 pNR pts had adj NIVO, 7 had adj TT and 7 had adj RT. The estimated grade 3-4 irAE rate at wk 12 was 24%. Due to toxicity, 10 pts (10%) received only 1 cycle I1N3 and in 3 pts ILN resection was not performed: 2 of these pts underwent TLND at wk 9 and one pt was not evaluated for path response. At data cutoff, the surgery-related grade 1,2 and 3 AE rates were 29%, 10% and 0% in pts who underwent ILN resection only vs 21%, 30% and 9% in pts who underwent subsequent TLND (p = 0.004). At ASCO 2020 all pts will have reached ≥12 wks FU. Conclusions: Neoadj I1N3 treatment induced a high pRR with tolerable toxicity. TLND was omitted in a major subset of pts, reducing surgical morbidity. Longer FU is needed to report safety and RFS when TLND is omitted in MPR pts. Clinical trial information: NCT02977052.

Personalized response-driven adjuvant therapy after combination ipilimumab and nivolumab in high-risk resectable stage III melanoma: PRADO trial

TPS9605

Background: Adjuvant (adj) immune checkpoint inhibition (ICI) improves relapse free survival (RFS) in stage III melanoma patients (pts). However, preclinical and translational data suggest that neo-adjuvant (neoadj) treatment might be favorable due to broader immune activation. The phase 1b OpACIN study comparing neoadj to adj IPI plus NIVO demonstrated a high pathological response rate (pRR) of 78% complicated by 90% gr 3-4 immune-related adverse events (irAEs). The phase 2 OpACIN-neo trial tested safety and efficacy of three different schemes of neoadj IPI+NIVO and identified two cycles of IPI 1mg/kg + NIVO 3mg/kg as well tolerated (20% gr 3-4 irAEs), with a high pRR of 77%. In both trials, none of the pts with a pathologic response have relapsed after a median follow-up of 30 and 8.3 months. In stage IV melanoma, long-term benefit is observed in patients achieving CR with ICI, even after cessation of therapy. This raises the question of whether a therapeutic lymph node dissection (TLND) can be omitted when a deep pathologic response with neoadj IPI+NIVO is achieved. Methods: The aim of this international multi-center investigator-initiated phase 2 PRADO extension study is to confirm the pRR and toxicity of 2 cycles of neoadjuvant IPI 1mg/kg + NIVO 3mg/kg (the preferred OPACIN-neo regimen) and to test response-driven subsequent therapy i.e. omitting surgery and adjuvant ICI based on the pathological response. 100-110 pts with stage IIIB/C melanoma and a measurable lymph node (≥15mm according to RECIST 1.1) will receive two cycles of IPI 1mg/kg + NIVO 3mg/kg after marker placement into the largest lymph node metastasis. After six weeks, pts will undergo resection of the index lymph node. For pCR/near pCR, pts will not undergo TLND; For pPR, pts will undergo TLND; and for pNR, pts will undergo TLND and start adjuvant NIVO or targeted therapy +/- radiotherapy for 52 weeks. Primary endpoints are pRR of marked lymph node and RFS at 24 months. Baseline biopsies, blood samples (week 0, 6, 12) and faeces (week 0, 6) will be collected for translational research analyses. The first patient in this trial was included in October 2018; 22 patients have been enrolled. Clinical trial information: NCT02977052.

Efficacy and safety of nivolumab (NIVO) in patients with advanced melanoma (MEL) and poor prognostic factors who progressed on or after ipilimumab (IPI): Results from a phase II study (CheckMate 172)

9524

Background: In the phase III CheckMate 037 study, NIVO improved the objective response rate and progression-free survival with less toxicity vs chemotherapy in patients (pts) with MEL who progressed after prior IPI treatment. We report the first efficacy and updated safety data from pts with MEL in CheckMate 172, including those with rare melanoma subtypes (uveal, mucosal), brain metastases, or an ECOG performance status (PS) of 2. Methods: In this ongoing phase II, single-arm, open-label, multicenter study, pts with MEL who progressed on or after IPI were treated with NIVO 3 mg/kg Q2W for up to 2 years until progression or unacceptable toxicity (NCT02156804). We report efficacy and updated safety data from 734 treated pts with ≥1 year of follow-up (database lock: November 2016). Results: Of 734 pts, 50% had LDH>ULN, 7% ECOG PS 2, 66% M1c disease, 15% a history of brain metastases, and 23% received ≥3 prior therapies. Overall, 593 pts (81%) received more than 4 doses of NIVO. Overall, response rate at 12 weeks was 32%, with a complete response in 1% (Table). The 1-year overall survival (OS) rate was 63%. Any grade and grade 3/4 treatment-related adverse events (AEs) occurred in 66% and 17% of pts, respectively. Discontinuations due to treatment-related AEs occurred in 4% of pts. The most common treatment-related select (potentially immune-related) AEs were diarrhea (12%), hypothyroidism (9%), and pruritus (7%). Conclusions: CheckMate 172 is the largest study of NIVO efficacy and safety in pts with MEL who progressed on or after IPI. NIVO demonstrated a safety profile consistent with that of prior clinical trials. Efficacy outcomes were encouraging in some difficult-to-treat subgroups of pts with poor prognostic factors, such as mucosal melanoma and brain metastases. Clinical trial information: NCT02156804. [Table: see text]

Effect of extending the original eligibility criteria for the “CROSS” neoadjuvant chemoradiotherapy on toxicity and survival in esophageal cancer

187

Background: Patients with curable esophageal cancer (EC) which proceed beyond the original CROSS eligibility criteria are also treated with neoadjuvant chemoradiotherapy (nCRT). This study assessed the effect of extending the CROSS eligibility criteria for nCRT on treatment related toxicity and overall survival (OS) in EC. Methods: Included were 161 patients with locally advanced EC (T1N1-3/T2-4aN0-3/M0), treated with the CROSS schedule followed by esophagectomy. Group 1 (N = 90) consisted of patients which met the CROSS criteria and patients in group 2 (N = 71) met the extended eligibility criteria, i.e. including a tumor length of > 8 cm (N = 23), > 10% weight loss (N = 35), > 2 – 4 cm extension in the stomach (N = 21), celiac lymph node metastasis (N = 13), and/or age > 75 years (N = 2). We assessed the differences in hematologic toxicity (≥ grade 3) and 90-day postoperative mortality. Moreover, we assessed the prognostic value on OS with multivariate Cox regression analysis. Results: No difference was found in hematologic toxicity and 90-day mortality. The OS differed significantly (P = 0.003), with a median of 37.3 (95% CI 10.56 – 64.0) and 17.2 (95% CI 13.8 – 20.6) months in group I and II, respectively. Pathological N-stage (P = 0.024), ypT-stage (P = 0.044), and group II (P = 0.006) were independent prognostic factors for OS. Conclusions: Extension of the CROSS study eligibility criteria for nCRT did not affect hematologic toxicity and postoperative mortality, but was prognostic for OS.

Impact of current “insufficient” clinical nodal staging on treatment decisions and response to neoadjuvant chemoradiotherapy in esophageal cancer patients

111

Background: Although essential in treatment decision making, clinical nodal (cN) staging in esophageal cancer (EC) remains difficult. We assessed the rate of nodal up- and downstaging and its prognostic value on 5-year disease-free survival (DFS) in EC patients treated with surgery-alone or with neoadjuvant chemoradiotherapy (nCRT). Methods: For this retrospective study, we included 395 EC patients who underwent a curative esophagectomy with or without nCRT between 2000 and 2015. The surgery-alone and nCRT group were matched on clinical T-stage (cT), cN-stage, and histopathological type using propensity score matching ( n=270). Staging consisted of PET with CT, or PET/CT, and endoscopic ultrasonography (n = 235). We compared cN and pathological N-stage (pN) and scored correct, down- and upstaging. The prognostic value of nodal up- and downstaging and localization of node metastases on 5-year DFS were assessed with multivariate Cox regression analysis (factors with a P-value <0.1 on univariate analysis). Results: Nodal upstaging (43.0% vs. 16.3%), correct staging (31.9% vs. 28.1%) and downstaging (25.2% vs. 55.6%) differed between the surgery-alone and nCRT group ( P<0.001). Nodal upstaging was commonly present in adenocarcinoma and cT3-4a tumors. Independent prognostic factors for DFS were pN ( P=0.002) and lymph-angioinvasion ( P=0.016) in the surgery and cN metastasis under the diaphragm ( P=0.012) and lymph node ratio ( P=0.034) in the nCRT group. Conclusions: In esophageal cancer, clinical lymph node staging is still insufficient with >25% nodal downstaging. This inaccuracy might impede assessment of true nodal response to nCRT, affording dubious decisions for a ‘wait-and-see’ strategy.

Baseline Biomarkers for Outcome of Melanoma Patients Treated with Pembrolizumab

PURPOSE

Biomarkers for outcome after immune-checkpoint blockade are strongly needed as these may influence individual treatment selection or sequence. We aimed to identify baseline factors associated with overall survival (OS) after pembrolizumab treatment in melanoma patients.

EXPERIMENTAL DESIGN

Serum lactate dehydrogenase (LDH), routine blood count parameters, and clinical characteristics were investigated in 616 patients. Endpoints were OS and best overall response following pembrolizumab treatment. Kaplan-Meier analysis and Cox regression were applied for survival analysis.

RESULTS

Relative eosinophil count (REC) ≥1.5%, relative lymphocyte count (RLC) ≥17.5%, ≤2.5-fold elevation of LDH, and the absence of metastasis other than soft-tissue/lung were associated with favorable OS in the discovery (n = 177) and the confirmation (n = 182) cohort and had independent positive impact (all P < 0.001). Their independent role was subsequently confirmed in the validation cohort (n = 257; all P < 0.01). The number of favorable factors was strongly associated with prognosis. One-year OS probabilities of 83.9% versus 14.7% and response rates of 58.3% versus 3.3% were observed in patients with four of four compared to those with none of four favorable baseline factors present, respectively.

CONCLUSIONS

High REC and RLC, low LDH, and absence of metastasis other than soft-tissue/lung are independent baseline characteristics associated with favorable OS of patients with melanoma treated with pembrolizumab. Presence of four favorable factors in combination identifies a subgroup with excellent prognosis. In contrast, patients with no favorable factors present have a poor prognosis, despite pembrolizumab, and additional treatment advances are still needed. A potential predictive impact needs to be further investigated. Clin Cancer Res; 22(22); 5487-96. ©2016 AACR.

Hormone receptors as a marker of poor survival in epithelial ovarian cancer

OBJECTIVE

Androgen receptor (AR), estrogen receptor α and β (ERα, ERβ), and progesterone receptor (PR) are potential therapeutic targets in epithelial ovarian cancer. In this study we evaluate the prognostic value of these hormone receptors in ovarian cancer patients.

METHODS

In a prospective multicenter randomized controlled phase II trial 196 ovarian cancer patients were randomized to carboplatin/docetaxel±celecoxib. Of 121 patients sufficient tumor tissue was available for hormone receptor analysis. Tissue micro-arrays were stained for AR, ERα, ERβ, and PR. Cluster analysis was performed to identify subgroups based on hormone receptor expression profile. Receptor expression was correlated to progression-free survival (PFS) and overall survival (OS) in uni- and multivariate analysis.

RESULTS

AR, ERα, ERβ, and PR were expressed in respectively 10%, 31%, 73%, and 19%. In patients with synchronous metastasis tissue available (n=69 patients), discordant receptor expression was observed in 9-32%. ERβ-expression was associated with poor PFS and OS (hazard ratios 1.88 and 1.92). Clustering analysis revealed a subgroup with hormone receptor negative disease that had a favorable PFS and OS.

CONCLUSION

Hormone receptors are expressed in the majority of ovarian cancer tumors and may serve as therapeutic targets. Clustering analysis can reveal subgroups with different outcome, which may prove valuable in selecting patients for endocrine therapy.

A comparison of carboplatin with paclitaxel and cisplatinum with 5-fluorouracil in definitive chemoradiotherapy in esophageal cancer patients

104

Background: In esophageal cancer (EC) patients not eligible for surgery definitive chemoradiation (dCRT) with curative intent using cisplatinum with 5-fluorouracil (5-FU) is the standard regime. Nowadays carboplatin and paclitaxel are also often used. In this study we compared survival and toxicity rates between both regimens. Methods: This multicentre study included 102 patients treated in five centres in the North Netherlands from 1996 till 2008. Forty-seven patients received cisplatinum/5-FU and 55 patients carboplatin/paclitaxel. Results: Overall survival (OS) was not different between the cisplatinum/5-FU and carboplatin/paclitaxel group (P=0.879, Hazard Ratio [HR] 0.97 confidence interval [CI] 0.62-1.51), with a median survival of respectively 16.1 (CI 11.8-20.5) and 13.8 (CI 10.8-16.9) months. Median disease free survival (DFS) was comparable (P=0.760, HR 0.93 CI 0.60-1.45) between the cisplatinum / 5-FU group (11.1 months, CI 6.9-15.3) and the carboplatin/paclitaxel group (9.7 months, CI 5.1-14.4). Groups were comparable except clinical T-stage was higher in the carboplatin/paclitaxel group (P=0.008), but a high clinical T-stage (cT4) was not related to OS and DFS in a univariate analysis (P=0.250 and P=0.201). A higher percentage of patients completed the carboplatin / paclitaxel regimen (82% compared to 57%, P=0.01). Hematological and non-hematological toxicity (≥ grade 3) was significantly lower in the carboplatin / paclitaxel group (4% and 18%) than in the cisplatinum/5-FU (19% and 38%, P=0.001). Conclusions: In this study we show comparable outcome, in terms of DFS and OS for carboplatin/paclitaxel compared to cisplatinum/5-FU as dCRT treatment in EC patients. Toxicity rates were lower in the carboplatin/paclitaxel group together with a higher treatment compliance. Carboplatin/paclitaxel as an alternative treatment for cisplatinum/5-FU is a good candidate regimen for further evaluation.

Preoperative chemoradiotherapy (CRT) in gastric cancer

89

Background: The prognosis of gastric cancer patients remains poor even after radical surgery. Although local control and survival are significantly improved by postoperative CRT, treatment compliance is frequently compromised due to severe toxicity. On the other hand, treatment compliance is good with preoperative chemotherapy (CT) in gastric cancer and preoperative CRT in esophageal cancer. The current study was initiated to investigate the feasibility and efficacy of preoperative CRT for marginally resectable and initially irresectable gastric cancer. Methods: Patients with marginally resectable and initially irresectable gastric cancer, without signs of peritonitis carcinomatosa, stage IB-IV(M0) were treated with CRT. Treatment consisted of irradiation to a total dose of 45 Gy given in 25 fractions of 1.8 Gy combined with concurrent weekly carboplatin (AUC 2) and paclitaxel (50mg/m2) on days 1, 8, 15, 22 and 29 of irradiation, followed by standardized surgery 4-6 weeks after the last irradiation. Results: Between December 2007 and January 2012, 25 patients with stage II-IV(M0) marginally resectable (n=13) or initially irresectable gastric cancer received preoperative CRT. One patient discontinued concurrent CT in the 4th week due to toxicity, but completed radiotherapy, and another patient stopped CRT after the 3rd week due to progressive disease. During CRT, grade III gastrointestinal adverse events (AE) occurred in 3 patients (12%), grade III hematological AE in 3 (12%) and grade III other AE in 2 (8%). Twenty-four patients (96%) were operated following CRT. Surgery-related complications consisted of anastomotic leakage in 3 patients (12%) and bowel perforation in 2 (8%). Postoperative mortality was 4%. A microscopically radical resection was achieved in 18 patients (72%), 8 of whom had initially irresectable gastric cancer. The pathologic complete response rate was 16% (4/25 patients). Conclusions: In this study, preoperative CRT for marginally resectable and initially irresectable gastric cancer was associated with manageable toxicity and resulted in an encouraging pathologic response rate. A multicenter phase II study has recently been initiated.