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Aim: To estimate incidence of stage III melanoma using the American Joint Committee on Cancer (AJCC) staging, 7th and 8th edition. Patients & methods: The SEER US cancer registry was analyzed (2010–2014). AJCC7 stages were recorded in the data; AJCC8 stages were inferred. Results: Of 106,195 melanoma patients, 7669 and 7342 had stage III melanoma by AJCC7 and AJCC8, respectively (95% overlap). Nearly 30% of patients with AJCC7 stage III melanoma were reclassified in a higher stage III group by AJCC8 versus 7% in lower stage group. Regardless of the AJCC edition, incidence of stage III melanoma has increased from 2010 to 2014 both overall and within each stage III group. Conclusion: Providing appropriate management to this growing population of high-risk patients is a priority.

Background In the precheckpoint inhibitor era, high-dose interferon was the only approved adjuvant therapy for high-risk melanoma. In this manuscript, we analyze the recurrence-free survival, overall survival and toxicity profile of adjuvant treatment with interleukin-2 (IL-2) and 5-(3,3-dimethyle-1-triazeno) imidazole-4-carboxamide (DTIC) for resected high-risk melanoma patients. Methods All patients with stage IIB, IIC or stage III melanoma who were treated with DTIC/IL-2 combination therapy at a single institution from 2000 to 2010 were identified from the University of Louisville Hospital medical record. Patients received 6 months of subcutaneous IL-2 (12 × 106 units days 1-4) and intravenous DTIC (750 mg/m2 day 1 of each cycle) every 28 days for 6 cycles. Individual medical records were accessed to collect the data. Results Of the 112 patients treated, all underwent surgical resection and then received adjuvant treatment. A total of 58.7% of the patients were male, 42.2% female; 99% were Caucasian. A total of 79 (72.5%) of the patients were alive at the time of analysis and 57 (47.7%) patients were currently event free. A total of 69 (63.3%) patients completed all 6 months of adjuvant combination treatment with 13.8% of the patients requiring IL-2 and 21.1% of the patients requiring DTIC dose reduction. Five year overall survival was 75.57% with recurrence-free survival of 53.05%. Conclusions For several decades, there has not been an ideal adjuvant treatment for patients with resected high risk melanoma. Our retrospective analysis suggests that combination therapy with DTIC/IL-2 is beneficial and relatively well tolerated as an alternative adjuvant treatment for patients with high-risk melanoma.

The aim of this study was to assess the prognostic importance of lymph node ratio (LNR) in stage III melanoma after complete lymph nodal dissections. From European Organization for Research and Treatment of Cancer randomized trials 18871, 18952, and 18991, 2358 patients had full information on positive and examined lymph nodes (LNs) and were included. Cox proportional hazards models stratified by trial were used to assess the prognostic impact of LNR adjusted for confounders on melanoma-specific survival. Optimal cutoff values for LNR were calculated for each LN dissection site (axillary, inguinal, and neck). LNR (≥ vs.35%: hazard ratio=1.44, 95% confidence interval: 1.23-1.69) and number of positive LNs appeared to be of independent strong prognostic importance. Dissection sites impacted the optimal LNR cutoff: 35% for axillary, 40% for inguinal, and 50% for neck dissections. Combining these into one 'high versus low LNR' resulted in a highly significant multivariately adjusted hazard ratio of 1.48 (95% confidence interval: 1.26-1.74). In subgroup analyses, LNR was only significant in advanced disease (American Joint Committee on Cancer stage N2b, N3; IIIC). LNR was most significant for inguinal dissections, followed by axillary dissections, but seemed less useful in neck dissections. LNR is an independent significant prognostic factor in stage III melanoma patients. Our study showed higher than previously reported cutoffs that differed per dissection site. However, because of conflicting results compared with other studies and apparent limited prognostic impact confined to subgroups, the practical use of LNR seems limited.

BACKGROUND In the previously reported primary analysis of this phase 3 trial, 12 months of adjuvant dabrafenib plus trametinib resulted in significantly longer relapse-free survival than placebo in patients with resected stage III melanoma with BRAF V600E or V600K mutations. To confirm the stability of the relapse-free survival benefit, longer-term data were needed. METHODS We randomly assigned 870 patients who had resected stage III melanoma with BRAF V600E or V600K mutations to receive 12 months of oral dabrafenib (at a dose of 150 mg twice daily) plus trametinib (2 mg once daily) or two matched placebos. The primary end point was relapse-free survival. Here, we report 5-year results for relapse-free survival and survival without distant metastasis as the site of the first relapse. Overall survival was not analyzed, since the required number of events to trigger the final overall survival analysis had not been reached. RESULTS The minimum duration of follow-up was 59 months (median patient follow-up, 60 months for dabrafenib plus trametinib and 58 months for placebo). At 5 years, the percentage of patients who were alive without relapse was 52% (95% confidence interval [CI], 48 to 58) with dabrafenib plus trametinib and 36% (95% CI, 32 to 41) with placebo (hazard ratio for relapse or death, 0.51; 95% CI, 0.42 to 0.61). The percentage of patients who were alive without distant metastasis was 65% (95% CI, 61 to 71) with dabrafenib plus trametinib and 54% (95% CI, 49 to 60) with placebo (hazard ratio for distant metastasis or death, 0.55; 95% CI, 0.44 to 0.70). No clinically meaningful between-group difference in the incidence or severity of serious adverse events was reported during the follow-up period. CONCLUSIONS In the 5-year follow-up of a phase 3 trial involving patients who had resected stage III melanoma with BRAF V600E or V600K mutations, 12 months of adjuvant therapy with dabrafenib plus trametinib resulted in a longer duration of survival without relapse or distant metastasis than placebo with no apparent long-term toxic effects. (Funded by GlaxoSmithKline and Novartis; COMBI-AD ClinicalTrials.gov number, NCT01682083; EudraCT number, 2012-001266-15.).

International audience; Background: Adoptive tumor-infiltrating lymphocytes (TIL) therapy and interleukin-2 (IL-2) have been investigated in melanoma.Aim: To confirm previously observed preventive effects of TIL + IL2 in a subgroup of patients with relapsing metastatic stage III melanoma.Methodology: Open-label, randomized two-group, multicenter five-year trial in adult stage III melanoma patients with only one invaded lymph node after complete resection. Patients received TIL + IL2 or abstention. TIL + IL2 was administered within 8 weeks after lymph node resection and 4 weeks after. Disease-free survival was assessed every 2 months up to month 18, every 3 months up to month 36 and every 4 months up to 5 years. A once-a-year follow-up was scheduled beyond the five-year follow-up. Safety was assessed throughout the trial.Results: Overall, 49 patients accounted for the modified intent-to-treat and 47 for the PP. Slightly more male than female patients participated; mean age was 57.7 ± 11.4 years in the TIL + IL2 group and 53.5 ± 13.0 years in the abstention group. After 5 years of follow-up, 11/26 patients in the TIL + IL2 group and 13/23 in the abstention group had relapsed. There was no statistical difference between the groups (HR: 0.63 CI 95% [0.28-1.41], p = 0.258), nine patients in the TIL + IL2 and 11 in the abstention group died with no significant difference between the two groups (HR: 0.65 CI95% [0.27 - 1.59], p = 0.34). Safety was good.Conclusion: We did not confirm results of a previous trial. However, ulceration of the primary melanoma may be considered predictive of the efficacy of TIL in melanoma in adjuvant setting, in a manner similar to interferon α.

Purpose: There is a need for sensitive, reproducible biomarkers for patients with stage III melanoma to guide clinical decision making. Circulating tumor cells (CTCs) can be detected in patients with melanoma; however, there are limited data regarding their significance in stage III disease. The aim of this study was to determine whether CTCs are associated with early relapse in stage III melanoma. Experimental Design: We prospectively assessed CTCs at first presentation in clinic (baseline) for 243 patients with stage III melanoma. CTCs were measured using the CellSearch System. Relapse-free survival (RFS) was compared between patients with one or more baseline CTC versus those with no CTCs. Log-rank test and Cox regression analysis were applied to establish associations of CTCs with RFS. Results: At least one baseline CTC was identified in 90 of 243 (37%) patients. Forty-five (19%), 67 (28%), 118 (49%), and 13 (5%) patients were stage IIIA, IIIB, IIIC, or IIID, respectively. CTC detection was not associated with substage, or primary tumor characteristics. Multivariable analysis demonstrated that the detection of ≥1 baseline CTC was significantly associated with decreased 6-month RFS [log-rank, P < 0.0001; HR, 3.62, 95% confidence interval (CI), 1.78–7.36; P < 0.0001] and 54-month RFS (log-rank, P = 0.01; HR, 1.69; 95% CI, 1.13–2.54; P = 0.01). Conclusions: ≥1 CTC was independently associated with melanoma relapse, suggesting that CTC assessment may be useful to identify patients at risk for relapse who could derive benefit from adjuvant therapy.

Following publication of the original article [1], the authors reported that one of the authors, Corrado Caracò, has been accidentally omitted from the author list. In this Correction the author has been added to the author list.

Even though both the involvement of regional lymph nodes and the number of metastatic lymph nodes are regarded as major determinants of survival in cutaneous melanoma, the extent of node dissection has been analyzed as an independent prognostic indicator in only a few studies. This study aims to determine how the extent of lymph node excision (EN) might predict the disease relapse and survival in melanoma.A total of 317 patients with stage III melanoma were included in the study and reviewed retrospectively. The patients were divided into 2 groups based on the number of the excised lymph nodes: EN1 for fewer than 10 and EN2 for 10 or more lymph nodes removed.The median number of positive nodes was 1 (range, 1-32). The largest group was N1 (52.4%), which was followed by N2 (29.6%) and N3 (18%). The median number of EN was 13 (range, 1-73). The patients were allocated to EN1 and EN2 as follows: 31.9% and 68.1%, respectively. The rates of EN2 patients were 62.2%, 72.2%, and 78.2% in N1, N2, and N3, respectively. For all patients, the estimated 5- and 10-year relapse-free survival rates were 41% and 39%, respectively; and the estimated 5- and 10-year overall survival rates were 51% and 42%, respectively. Extension of lymph node excision was found to be not prognostic for relapse and survival (P = 0.55 and P = 0.88, respectively).Extension of lymph node excision has no impact on relapse and survival of stage III cutaneous melanomas.

BACKGROUND Comorbidity burden is associated with development of cancer, stage at diagnosis, and treatment outcomes. We evaluated the association between comorbidity burden, receipt of adjuvant immunotherapy, and survival in patients with stage III melanoma. METHODS Using the National Cancer Database, we identified 16,906 patients with stage III melanoma who underwent surgery of the primary site. Outcomes included receipt of adjuvant immunotherapy and overall survival; independent variables included Charlson/Deyo comorbidity index (CDI) and receipt of adjuvant immunotherapy. RESULTS Patients with CDI scores of two or more averaged 30.0% and 30.9% lower adjusted odds of receiving adjuvant immunotherapy relative to patients with a CDI score of zero or one, respectively (P = 0.001 and 0.002, respectively). Longer survival was associated with lower CDI scores (all P

Objectives: Pathological stage III melanoma patients have variable clinical presentation and outcome when divided by substages, and the number of metastatic lymph nodes is the most significant inde...

Aims: To evaluate the cost-effectiveness of adjuvant pembrolizumab relative to observation alone following complete resection of high-risk stage III melanoma with lymph node involvement, from a US ...

International audience; Improved knowledge of sentinel node procedures coupled with the results of adjuvant clinical trials in stage III melanoma have prompted the French Cutaneous Oncology Group to propose new guidelines for the management of stage III melanoma. These guidelines comply with the principles of the evidence-based medicine.

Melanoma is a form of skin cancer that is frequently diagnosed at early stages. In most cases, surgical resection is curative. In case of thicker melanomas (> pT1b) without clinical or instrumental evidence of metastasis, a sentinel lymph node biopsy is recommended for staging purposes. If the lymph nodes are the only site of disease (macroscopic or microscopic> 1mm), configuring stage III, the international guidelines recommend the use of adjuvant therapy with checkpoint inhibitors (nivolumab or pembrolizumab) or targeted therapies (dabrafenib plus trametinib). These drugs have shown a significant increase in recurrence-free survival, although some doubts and open questions remain. Specifically, none of the available treatments has shown a clear benefit in the overall survival rates, the advantages they give in stage IIIA are not well known, and finally there are still no prospective clinical studies identifying the best approach to continue the therapeutic process in case of relapse. Furthermore, there are new opportunities opening up with the upcoming results of the neoadjuvant trials that could revolutionize the treatment of clinically evident stage III melanoma.

9500 Background: The phase 3 double-blind EORTC 1325/KEYNOTE-054 trial evaluated pembrolizumab (pembro) vs placebo in stage III cutaneous melanoma patients (pts) with complete resection of lymph nodes. Pembro improved RFS (hazard ratio [HR] 0.57) and DMFS (HR 0.60) (Eggermont, NEJM 2018, TLO 2021). In the pembro group, the incidence of immune related AE (irAE) grade 1-5 was 37%, and of grade 3-5 was 7%. We present the safety profile, response rate and PFS for the subset of pts who had a recurrence and crossed over or were rechallenged with pembrolizumab, within protocol. Methods: Pts were randomized to receive iv. pembro 200 mg (N=514) or placebo (N=505) every 3 weeks for a total of 18 doses (~1 year). Upon recurrence with no brain metastases, pts with an ECOG PS 0-2 were eligible to enter part 2 of the study, i.e. to receive pembro 200 mg iv. every 3 weeks for a maximum of 2 years, for crossover (those who received placebo) or rechallenge (those who recurred ≥6 months after completing one year of pembro therapy). Treatment was stopped in case of disease progression (RECIST 1.1) or unacceptable toxicity. Results: At the clinical cut-off (16-Oct-2020), 298 (59%) pts had a disease recurrence in the placebo group; 155 pts participated in the crossover part 2 of the trial. A total of 297 (58%) pts completed the 1-yr pembro adjuvant treatment, of whom 47 had a recurrence ≥6 mths from the stop of treatment and 20 entered in the rechallenge part of the trial. Among 175 pts who started pembro in Part 2, 160 discontinued due to completion of therapy (N=24), disease progression (N=88), toxicity (N=20), investigator's decision (N=21), or other reason (N=7); 15 pts were still on-treatment. Results for the 2 groups are provided in the table. The median number of doses was 12 and 5.5, respectively (resp), and the median follow-up was 41 and 19 mts, resp. Among the 175 pts, 51 (29%) had a grade 1-4 irAE (by group: 47 [30%] and 4 [20%] resp) and 11 (6%) a grade 3-4 irAE. Conclusions: Pembrolizumab treatment after crossover yielded a 39% ORR in evaluable pts and an overall 3-yr PFS of ̃32%, but after rechallenge the efficacy was lower. Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA The median PFS (95% CI) from start of Part 2 was 14 (5-27) and 8 (5-15) mts for stage III-resected and III/IV various, resp. Among the 80 stage IV crossover pts with evaluable disease, 31 (39%) had an objective response: 14 (18%) CR, 17 (21%) PR. The 2-yr PFS rate from response was 69% (95% CI 48-83%). For these 80 pts, the median PFS was 6.1 mts and the 3-yr PFS rate was 31% (95% CI 21-41%). Among 9 stage IV rechallenged pts with an evaluable disease, 1 (11%) reached CR, 3 had SD and 5 PD. Clinical trial information: NCT02362594. [Table: see text]

e18758 Background: There are now numerous effective adjuvant immunotherapy options for surgically resected stage III melanoma including novel checkpoint inhibitors and targeted therapies. Current guidelines recommend that the decision to treat stage III melanoma with adjuvant immunotherapy should be individualized and based upon disease burden, patient goals and anticipated therapy tolerance. We sought to assess the contribution of patient, tumor and facility factors on the implementation of immunotherapy in patients with surgically resected stage III melanoma. Methods: Using the National Cancer Database (NCDB), patients from 2012-2017 that underwent excision and were found to have a positive sentinel node were identified. A multivariable mixed effects logistic regression model with a random intercept for site was used to determine the effect of patient, tumor, and facility variables on the probability of immunotherapy. Reference Effect Measures (REM) were used to estimate the variation in immunotherapy use due to unmeasured facility factors (contextual effects) after adjusting for measured patient, tumor, and facility variables. Results: From 2012 to 2017, the percent of patients with stage III melanoma treated with adjuvant immunotherapy increased from 23.7% to 38.5% (p < 0.05). Overall, younger patients and patients with private insurance were more likely to receive immunotherapy. Tumor factors associated with increased use of adjuvant immunotherapy included increasing depth, mitotic rate ³1, ulceration, lymphovascular invasion (LVI), and undergoing a completion lymph node dissection (CLND). Additionally, treatment at a facility with a surgical volume

e21570 Background: Advancements in systemic therapy have reduced recurrence, and the adoption of nodal surveillance in place of dissection has reduced morbidity for patients with Stage III melanoma. The objective of this study was to describe the timing and pattern of recurrence in stage III melanoma patients and evaluate the impact of adjuvant treatment and nodal surveillance. Methods: A multicenter retrospective chart review of patients with pathologically confirmed Stage III cutaneous melanoma seen at either the Juravinski Cancer Centre or Walker Family Cancer Centre in Ontario, Canada from January 1, 2017 to December 31, 2019. Results: There were 137 patients with Stage III melanoma: 18% IIIA, 22% IIIB, 52% IIIC, and 8% Stage IIID as per the 8th American Joint Committee on Cancer (AJCC) 2018 staging system. 103 (75%) patients had sentinel lymph node biopsy (SLNB) only as part of initial surgical therapy, 6 (4%) had SLNB with completion dissection, and 25 (18%) had upfront radical nodal dissection. 67 (49%) patients received adjuvant therapy, of which 50 (74%) had immunotherapy, 17 (25%) received BRAF-targeted therapy, and 1 (1%) had interferon. 54 (39%) patients developed recurrent disease, with a median time to recurrence of 8.5 months (IQR: 4.3-14.9). The recurrence rates were 63% in patients who did not have adjuvant treatment and 37% in those who had adjuvant therapy, with a median time-to-recurrence of 7.5 and 9.0 months respectively. There were 30 (56%) loco-regional recurrences and 24 (44%) distant recurrences. Of the patients with loco-regional recurrence, 26 (87%) had SLNB only compared to 4 (13%) who had upfront or completion dissection. 12 (24%) patients recurred while on adjuvant treatment (7 distant recurrences and 5 loco-regional recurrences), and 8 (13%) patients recurred following completion of adjuvant treatment (5 distant recurrences and 3 loco-regional recurrences). Recurrences were detected by patients, clinicians, CT and nodal US surveillance in 43%, 20%, 28% and 9% of cases, respectively. The majority of loco-regional recurrence was detected clinically (67%) rather than by radiologic surveillance (33%). Of the 30 loco-regional recurrences, 24 underwent surgical resection of the recurrence, 4 had subsequent systemic therapy without surgery, 1 had intra-tumoral injections and 1 had no treatment. Conclusions: Recurrences in Stage III melanoma occur early, often within a year, with higher rates of loco-regional rather than distant disease. Recurrence rates were lower in those who received adjuvant therapy, but the majority of recurrences were detected by patients or clinicians, including loco-regional recurrences in patients who had SLNB only despite surveillance nodal US.

9579 Background: Recently, trials have shown the benefit of adjuvant aPD-1 therapy in macroscopic stage III melanoma patients. This treatment has been incorporated in daily clinical practice, however, a substantial part of patients still does not benefit from this therapy, as they develop recurrences. The aim of this study is to evaluate the results of adjuvant aPD-1 therapy and the potency of the IFNγ signature as a prognostic or predictive marker, as it has proven to be predictive of response in neoadjuvant trials. Methods: Patients participating in an ongoing biobank study and naïve for systemic therapy were included, between 10-2017 and 06-2020, after complete resection of macroscopic stage III melanoma. Approval and reimbursement of adjuvant therapy in the Netherlands started in 12-2018, resulting in 2 cohorts of similar high risk patients: prior to availability of adjuvant aPD-1 (cohort A) and thereafter (cohort B). Data cut-off for clinical data was January 1st 2021. Transcriptome sequencing was performed on samples of stage III melanoma by CeGaT GmbH, IFNγ signature was determined on these data with the median as cut-off. Clinical data were compared between cohort A and B as intention-to-treat population, including patients with a recurrence before adjuvant therapy start (n=10). Results: In total, 99 patients were included: 50 in cohort A and 49 in cohort B. Majority of included patients had thick primary melanomas (Breslow >2mm in 59.6%) and stage IIIC/IIID disease (83.3%) according to AJCC 8th edition. At a median follow-up of 20.6 months (95% confidence interval [CI] 16.6-24.7), median recurrence-free survival (RFS) was 6.1 months (95%CI 3.9-8.4) versus 22.8 months (95%CI 8.7-36.9), significantly in favor of cohort B (p=0.011). Median overall survival (OS) was not reached in both patient groups, but was overall significantly different (p=0.040), favoring cohort B. RNA sequencing was performed in 25 patients who received adjuvant therapy and in 24 who did not, excluding patients with an early recurrence (

9577 Background: The management of patients with resected stage III melanoma has changed in recent years, and real-world data on recurrence patterns and adjuvant therapy responses are scarce. This study assessed adjuvant treatment patterns and outcomes in patients with advanced melanoma by BRAF status and relapse location. Methods: Patients diagnosed with stage III advanced melanoma between January 2011 and February 2020 in the nationwide Flatiron Health electronic health record–derived deidentified database were included if they were ≥18 years, received approved first-line (1L) adjuvant therapy after January 2018 with checkpoint inhibitors (CPIs; eg, nivolumab, pembrolizumab) or targeted therapies (TTs; eg, dabrafenib/trametinib), had 6 months’ follow-up and had ≥1 visit after starting adjuvant therapy (Cohort 1). Patients from Cohort 1 were included in Cohort 2 if they had a recurrence following initiation of adjuvant therapy, and those from Cohort 2 were included in Cohort 3 if they had a distant recurrence and available documented BRAF status at any time. Time to next systemic treatment (TTNT), overall survival (OS) and relapse free survival (RFS) were estimated using Kaplan-Meier (KM) methods from adjuvant therapy start (Cohort 1), first recurrence date (Cohort 2) or first distant recurrence date (Cohort 3). Results: Cohort 1 included 447 patients receiving 1L adjuvant therapy; Cohort 2 included patients after first distant (n = 47) or local (n = 35) relapse; Cohort 3 included distant-recurrent patients with tumors that were BRAF wild type (WT) (n = 22) or BRAF mutant (n = 23). The majority of patients were aged < 65 years. Across cohorts, relative use of TTs vs CPIs was similar: Cohort 1 (4.5% vs 96%), Cohort 2 (2.4% vs 98%) and Cohort 3 (2.2% vs 98%). Nivolumab was the most frequent treatment used across cohorts (84%-88%). In Cohort 1, 1- and 2-year KM probabilities for OS, RFS and TTNT were 93.5%/83.8%, 83.2%/70.6% and 84.0%/62.4%, respectively. In Cohort 2, for patients with local recurrence, 6- and 12-month OS probabilities were 93.4% and 78.8%, respectively, which were substantially higher than those for patients with distant recurrence (64.5% and 46.9%). In Cohort 3, for patients with documented BRAF mutations, 6- and 12-month OS rates from disease recurrence were 79.1% and 49.4%, respectively, which were greater than for those with BRAF-WT tumors (54.1% and 46.3%). Conclusions: Early RFS and OS outcomes for patients with surgically resected Stage III melanoma appear comparable to those reported in randomized clinical studies. The majority of patients with advanced melanoma, including patients who experienced recurrence, initiated treatment with CPIs. OS rates were numerically greater for Cohort 3 patients with BRAF-mutant tumors. Outcomes for patients with distant recurrence after adjuvant therapy remain unfavorable and represent a continued unmet medical need.

9502 Background: Neoadjuvant therapy (NT) for pts with clinical stage III melanoma remains an active area of research interest. Recent NT trial data demonstrates that achieving a pathologic complete response (pCR) correlates with improved relapse-free (RFS) and overall survival (OS). Checkpoint inhibitor (CPI) NT with either high or low dose ipilimumab and nivolumab regimens produces a high pCR rate of 30-45% but with grade 3-4 toxicity rate of 20-90%. In metastatic melanoma (MM), the combination of nivo with rela (anti Lymphocyte Activation Gene-3 antibody) has demonstrated a favorable toxicity profile and responses in both CPI-naïve and refractory MM. We hypothesized that NT with nivo + rela will safely achieve high pCR rates and provide insights into mechanisms of response and resistance to this regimen. Methods: We conducted a multi-institutional, investigator-initiated single arm study (NCT02519322) enrolling pts with clinical stage III or oligometastatic stage IV melanoma with RECIST 1.1 measurable, surgically-resectable disease. Pts were enrolled at 2 sites and received nivo 480mg IV with rela 160mg IV on wks 1 and 5. Radiographic response (RECIST 1.1) was assessed after completion of NT; surgery was conducted at wk 9 and specimens were assessed for pathologic response per established criteria. Pts received up to 10 additional doses of nivo and rela after surgery, with scans every 3 mo to assess for recurrence. The primary study objective was determination of pCR rate. Secondary objectives included safety, radiographic response by RECIST 1.1, event-free survival (EFS), RFS, and OS analyses. Blood and tissue were collected at baseline, at day 15, day 28, and at surgery for correlative analyses. Results: A total of 30 pts (19 males, median age 60) were enrolled with clinical stage IIIB/IIIC/IIID/IV (M1a) in 18/8/2/2 pts, respectively. 29 pts underwent surgery; 1 pt developed distant metastatic disease while on NT. pCR rate was 59% and near pCR ( < 10% viable tumor) was 7% for a major pathologic response (MPR, pCR + near pCR) of 66%. 7% of pts achieved a pPR (10-50% viable tumor) and 27% pNR (≥50% viable tumor). RECIST ORR was 57%. With a median follow up of 16.2 mos, the 1 -year EFS was 90%, RFS was 93%, and OS was 95%. 1-year RFS for MPR was 100% compared to 80% for non-MPR pts (p = 0.016). There were no treatment related gr 3/4 AEs that arose during NT; 26% of pts had a gr 3/4 AE that began during adjuvant treatment. Conclusions: Neoadjuvant and adjuvant treatment with nivo and rela achieved high pCR and MPR rates with a favorable toxicity profile in the neoadjuvant and adjuvant settings. Pts with MPR had improved outcomes compared to non-MPR pts. Translational studies to discern mechanisms of response and resistance to this combination are underway. Clinical trial information: NCT02519322.

e21569 Background: Neoadjuvant immunotherapy with nivolumab 3mg/kg and ipilimumab 1mg/kg for two cycles(N3+I1) or anti-PD1 for 3-8 weeks for clinical stage III melanoma have shown rates of pCR/near-pCR about 60% or 30%, respectively. The prognosis of this group seems to be excellent so far. On the other hand, patients classified as pathological non-response have a worse outcome and early identification of this group may allow us to tailor treatment before surgery. Methods: We conducted a retrospective analysis of patients with clinical stage III melanoma treated with neoadjuvant immune checkpoint blockade who did baseline and pre-operative FDG-PET/CT. The total number of FGD avid lesions and the percentual difference between the maximum SUV per lesion was calculated. The pathological results were correlated to FGD-PET/CT findings. Results: Between January 2019 and January 2021, nine patients with clinical stage III melanoma were identified. Six patients received Nivolumab 3m/kg and Ipilimumab 1mg/kg for two cycles and 3 received anti-PD1 for 60 days. Baseline FDG-PET/CT showed just one avid lesion in 7 patients, 2 avid lesions in one patient and 3 avid lesions in one patient. All known lesions identified by CT scan were also captured by FGD-PET/CT. After the neoadjuvant treatment, 4 patients achieved pCR/near-pCR. All of them were treated with N3+I1. Two of them had metabolic complete response (including the one with 3 PET- avid lesions) and 2 had reduction on FDG concentration (-31% and – 76%). Three patients had absence of response: 100% of viable tumor cells (VTC), all of them with increase in FDG concentration (+12% to + 307%) and appearance of a new lesion in one case. Two out of them were treated with anti-PD1. One patient had partial response (40% of VTC). Interestingly, this patient developed sarcoidosis-like reaction with increase of SUV in the index lesion (+68%) and appearance of mediastinal lymph-nodes. One patient, who had two lesions, presented a mixed response: complete response in one and 90% of VTC in the other. FDG-PET/CT was able to detect both responses (metabolic complete response and increase of FGD concentration of 17%, respectively). Conclusions: Reduction in FGD-PET/CT concentration with no appearance of new lesion(s) is associated with significant pathological response. An increase of SUV or appearance of new lesion(s) should be carefully interpreted.

9551 Background: Recent data suggest that patients with stage III melanoma are at high enough risk for developing CNS metastases to consider routine surveillance neuroimaging (Journal of Clinical Oncology; PMID: 31990608). Given that a subset of stage II patients have a worse prognosis than stage III patients, we investigated the risk of developing brain metastases in stage II disease and compared it to the risk in stage III disease. Methods: We studied a cohort of prospectively enrolled melanoma patients who had protocol driven follow-up at New York University (NYU) Langone Health. We investigated both the incidence and time to development of CNS metastases, and explored whether the frequency of CNS metastases as a first isolated site of distant disease varies among the different stages. Results: The study cohort included a total of 1,102 patients (stage II: n = 619 with median follow-up 56.5 months; stage III: n = 483 with median follow-up 40.9 months). 85/619 (14%) stage II and 91/483 (19%) stage III patients developed CNS metastases (p = 0.03). The estimated 5-year cumulative incidence was 9% in stage IIA, 14% in stage IIB, and 29% in stage IIC patients (p = 0.0001). It was 10% in stage IIIA, 32% in stage IIIB, 23% in stage IIIC, and 49% in stage IIID (p = 0.0001). The CNS was the site of first metastasis for 32/154 (21%) stage II patients who developed distant disease compared to 28/214 (13%) stage III patients (p = 0.06). Conclusions: A subset of stage II patients are at an elevated risk for developing CNS metastases within 5 years of their initial diagnosis, which is comparable to that seen in stage III patients. The frequency of the CNS as a first site of metastasis in stage II melanoma suggests a propensity for brain tropism that cannot only be explained by a generalized pro-metastatic phenotype. Surveillance strategies that incorporate serial neuroimaging should be considered for these individuals.

Melanoma is one of the most aggressive skin cancers. The 5-year survival rate of stage III melanoma patients ranges from 93% (IIIA) to 32% (IIID) with a high risk of recurrence after complete surgery. The introduction of target and immune therapies has dramatically improved the overall survival, but the identification of patients with a high risk of relapse who will benefit from adjuvant therapy and the determination of the best treatment choice remain crucial. Currently, patient prognosis is based on clinico-pathological features, highlighting the urgent need of predictive and prognostic markers to improve patient management. In recent years, many groups have focused their attention on identifying molecular biomarkers with prognostic and predictive potential. In this review, we examined the main candidate biomarkers reported in the literature.

A 51-year old woman with stage III melanoma participated in a phase II clinical trial in which she received subcutaneous rhGM-CSF injections for 3 years. She was in remission by the end of the trial. Seven months after discontinuing GM-CSF she had her first MS event. The unique timeline of rh-GM-CSF injections in a melanoma trial, during which yearly MRI scans showed subtle stable demyelination followed by RRMS onset shortly after discontinuation of treatment, may provide some insight on the role of GM-CSF in MS.

Background In the multicenter investigator-initiated OpACIN-neo trial, patients (pts) with macroscopic stage III melanoma were randomized (stratified by center) to three different dosing schemes of neoadjuvant ipilimumab (IPI) + nivolumab (NIVO). Two cycles IPI 1 mg/kg + NIVO 3 mg/kg was identified as the most favorable regimen with 20% grade 3-4 adverse events and a pathologic response rate (pRR) of 77%. After a median follow-up of 17.7 months, relapses were observed in 1/64 (2%) of the pts with a pathologic response, and in 13/21 (62%) of the non-responders. Post-hoc analyses according to continent of study inclusion were conducted to investigate potential differences between pts treated in Europe (EU) and in Australia (AUS). Methods We evaluated baseline patient characteristics, safety and efficacy in terms of pathologic response in pts treated in EU (n=48) and AUS (n=38). Mutational (mut) load of baseline biopsies was assessed using whole exome sequencing. Multivariate analyses were performed using the logistic regression method. Median follow-up was 18.2 months for EU pts and 16.6 months for AUS pts. Results Baseline characteristics (AUS vs EU) differed in age (median 60 vs 53 year [yr], p=0.017). There were numerically more male pts in the Australian cohort (65.8 vs 50.0%, p=0.142) and more pts with unknown primary melanoma (36.8 vs 20.8%, p=0.100). A numerical higher pRR was observed in AUS pts vs EU pts (84.2% vs 64.7%, OR 2.50, p=0.092). The pRR was significantly higher for older pts (OR per yr 1.059, p=0.003), males (83.7% vs 63.9%, OR 2.90, p=0.041), and pts with higher mut load (OR per mutation 1.002, p=0.014). Mut load was higher in pts with pathologic response (p=0.0013) and in AUS pts (p=0.0003). There was a positive correlation between age and mut load (R=0.26, p=0.043). Multivariate analysis including continent, age, gender and mut load revealed that only mut load was significantly associated with response (OR 1.002, p=0.037).The frequency of grade 3-5 toxicities was the same in pts 60 yr (42.3% vs 32.4%, p=0.353). Conclusion The numerical higher pRR in AUS vs EU melanoma pts upon neoadjuvant IPI + NIVO appears mostly driven by a higher mut load found in the melanomas of AUS pts. AUS pts were older and there was a positive correlation between age and mut load, indicating that the higher mut load in AUS pts might be explained by higher age. It remains to be elucidated if continental variance in sun exposure also contributed to the difference in mut load. The fact that older pts achieve a higher response rate in absence of increased toxicity rates indicates that older pts should not be withheld neoadjuvant IPI + NIVO. Citation Format: Irene L. Reijers, Elisa A. Rozeman, Alexander M. Menzies, Judith M. Versluis, Bart A. van de Wiel, Karolina Sikorska, Hanna Eriksson, Kerwin Shannon, Carolien Bierman, Harm van Tinteren, Maria Gonzalez, Andrew J. Spillane, Robyn P. Saw, Alexander C. van Akkooi, Richard A. Scolyer, Johan Hansson, Georgina V. Long, Christian U. Blank. Different pathologic response rates between Australia and Europe in macroscopic stage III melanoma patients upon neoadjuvant ipilimumab plus nivolumab in the phase II OpACIN-neo trial [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3271.

Introduction The outcome of high-risk stage III melanoma patients was poor with a 5-year overall survival (OS) rate of Methods The phase 1b OpACIN trial randomized 20 stage IIIB/IIIC melanoma patients to receive either 4 cycles of adjuvant IPI 3 mg/kg plus NIVO 1 mg/kg or 2 cycles of neoadjuvant IPI plus NIVO at the same dose followed by 2 cycles adjuvant IPI plus NIVO. In the OpACIN-neo trial, 86 patients were randomized to 2 cycles neoadjuvant in arm A: 2x IPI 3 mg/kg plus NIVO 1 mg/kg q3w (n=30), arm B: 2x IPI 1 mg/kg plus NIVO 3 mg/kg q3w (n=30), and arm C: 2x IPI 3 mg/kg q3w followed immediately by 2x NIVO 3 mg/kg q3w (n=26). Pathologic response was defined as Results After a median follow-up of 36 months for the OpACIN and 18 months for the OpACIN-neo trial, only 1 of 71 patients (1.4%) with a pathologic response on neoadjuvant therapy had relapsed, versus 15 of 23 patients (65.2%) without a pathologic response. The estimated 3-year RFS rate for the neoadjuvant arm was 80% (95% CI: 59%-100%) versus 60% (95% CI: 36%-100%) for the adjuvant arm in the OpACIN trial. The median RFS was not reached in any of the arms within the OpACIN-neo trial. Estimated 18-months RFS rate was 85% (95% CI: 78%-93%) for all patients; for arm A 90% (95% CI: 80%-100%), for arm B 82% (95% CI: 70%-98%) and for arm C 83% (95% CI: 70%-100%). Translational analyses showed that tumor mutational burden and interferon-γ gene expression score at baseline, both separate and combined, can function as predictors of response. Conclusions OpACIN showed for the first time a potential benefit of neoadjuvant versus adjuvant immunotherapy, while OpACIN-neo confirmed the high pathologic response rates which can be achieved by neoadjuvant IPI plus NIVO. Both trials argue for pathologic response as a surrogate markers for RFS. Clinical trial information: NCT02437279, NCT02977052 Citation Format: Christian U. Blank, Judith M. Versluis, Elisa A. Rozeman, Alexander M. Menzies, Irene L. Reijers, Oscar Krijgsman, Esmée P. Hoefsmit, Bart A. van de Wiel, Karolina Sikorska, Carolien Bierman, Petros Dimitriadis, Maria Gonzalez, Annegien Broeks, Ron M. Kerkhoven, Andrew J. Spillane, John B. Haanen, Winan J. van Houdt, Robyn P. Saw, Hanna Eriksson, Alexander C. van Akkooi, Richard A. Scolyer, Ton N. Schumacher, Georgina V. Long. 36-months and 18-months relapse-free survival after (neo)adjuvant ipilimumab plus nivolumab in macroscopic stage III melanoma patients - update of the OpACIN and OpACIN-neo trials [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3412.

e22086 Background: Patients with stage III melanoma are at high risk for recurrence after resection of the primary lesion. The Combi-AD study showed adjuvant therapy with BRAF inhibitor, dabrafenib (D), and MEK inhibitor, trametinib (T), in patients with resected stage III BRAF mutant melanoma offers recurrence free survival benefit at 3 and 4 years compared to placebo. In this study, adverse events led to dose interruption in 66% of patients, dose reduction in 38% of patients, and permanent discontinuation in 26% of patients. This is a retrospective case series of patients with resected stage III melanoma treated with adjuvant BRAF and MEK inhibition reporting toxicities in a real-world population. Methods: Medical records of all patients with resected Stage III melanoma treated with adjuvant D+T by multiple, independent oncologists at our institution between November 2017 and December 2019 were reviewed. Planned treatment was dabrafenib 150 mg bid and trametinib 2 mg daily for 1 year. Primary outcome of interest was development of toxicities. Secondary outcomes included number of treatment interruptions, dose reductions, and total time on combination therapy. Results: Twenty patients were treated with adjuvant D+T during the study period. Eighteen patients (90%) required at least 1 treatment interruption due to adverse events. Eleven patients (55%) required a dose reduction and 14 (70%) permanently discontinued therapy due to an adverse event. The 9 patients who did not require dose reduction had been initiated on a lower dose of dabrafenib (75 mg BID) due to physician experience with toxicities in prior patients. The most common treatment-limiting adverse events were recurrent pyrexia (85%) and liver laboratory abnormalities (50%). Permanent discontinuation was secondary to recurrent pyrexia in 9 patients (45%) and liver laboratory abnormalities in 5 patients (25%). For the 16 patients who completed or discontinued therapy, the median total time on therapy was 76 days, 20.8% of the intended duration. The majority of these patients never reached the FDA labeled combination dose. Conclusions: We report our findings of the side effects of adjuvant D+T to demonstrate the frequency and severity of treatment limiting toxicities in a real-world population, which exceeds what has been reported in clinical trials. Adjuvant D+T is an approved treatment for resected stage III melanoma but requires diligent toxicity assessment and management.

TPS10088 Background: Recent clinical trials of neoadjuvant (neo-adj) ipilimumab combined with nivolumab (OpACIN & OpACIN-neo) in resectable stage III melanoma show that a pathological response ( < 50% viable tumour at the tumour bed as determined by histopathological analysis) is associated with a prolonged relapse-free survival compared to no pathological response. Furthermore, recurrences seldom occur in those who have a pathological response following neo-adj immunotherapy with only 1/71 pts (1.4%) having recurred. In contrast, 15/23 (65.2%) pts with no pathological response have relapsed to date. The NeoPeLe trial will test the hypothesis that the synergistic combination of PD-1 blockade (pembrolizumab) with anti-angiogenic/multiple RTK inhibitor (lenvatinib) will result in a high rate of pathological response in the resected surgical specimen with a low rate of toxicity. Tissue and blood biomarkers are drawn at several timepoints and correlated to clinical and pathological endpoints to explore mechanisms of response and resistance. We will compare pathological response rate, and other clinical outcomes in this study, with previously published neo-adj clinical trials to select the best schedules for larger-scale clinical testing. Across neo-adj studies, we will also analyse the tissue collected to explore determinants of the optimal therapy for individual pts, whilst minimising toxicity. Methods: Eligible pts with stage IIIB/C/D, resectable and measurable (RECIST 1.1) nodal metastatic melanoma will be enrolled to this phase II single-centre trial (n = 20). All pts undergo complete nodal resection (RES) at wk 6 following neo-adj therapy with pembrolizumab (200mg, IV, 3 wkly) and lenvatinib (20mg, oral, daily). Adjuvant therapy with pembrolizumab is given for 46 wks after RES. After 52 wks of the study treatment, pts will be followed for relapse and survival for 5 years. CT and FDG PET/CT are used to measure response and exclude progression in the neo-adj phase, and to monitor for recurrence during adj and post treatment phases. Blood and tumour samples are collected at baseline, day 8, RES and at relapse if feasible. Faecal samples are collected at baseline and before RES. The primary endpoint is the complete pathological response rate at RES following 6 wks of neo-adj therapy. Secondary endpoints include RECIST response, metabolic response, OS, RFS, safety/tolerability, surgical outcomes, quality of life, and biomarker analyses. Clinical trial information: NCTNCT04207086.

10015 Background: Early results of the OpACIN-neo study testing 3 different dosing schedules of neoadjuvant IPI + NIVO demonstrated that 2 cycles IPI 1mg/kg + NIVO 3mg/kg (IPI1NIVO3, arm B) was the most favorable schedule with 20% grade 3-4 immunotherapy-related adverse events (irAEs) and a pathologic response rate (pRR) of 77%. After a median follow-up (FU) of 8.3 months, none of the 64 patients (pts) with a pathologic (path) response ( < 50% viable tumor cells) versus 9/21 (43%) without a path response had relapsed. Here, we present the updated 2-year RFS, EFS and long-term toxicity data. Methods: In the phase 2 multi-center OpACIN-neo trial, 86 stage III melanoma pts with resectable and RECIST 1.1 measurable lymph node metastasis were randomized between 3 different dosing schedules of neoadjuvant IPI + NIVO: arm A: 2x IPI3+NIVO1 Q3W (n = 30), arm B: 2x IPI1+NIVO3 Q3W (n = 30), and arm C: 2x IPI3 Q3W followed by 2x NIVO3 Q2W (n = 26). Lymph node dissection was scheduled at week 6. Primary endpoints were toxicity, radiologic RR and pRR; RFS and EFS were secondary endpoints. Results: After a median FU of 24.6 months, the median RFS and EFS was not reached in any of the 3 arms. In total, 2 pts progressed before surgery, 12 pts relapsed (11 pts without path response and 1 pt with pCR) and 5 pts died (4 due to melanoma and one pt due to toxicity). Estimated 24-months RFS was 84% (95% CI 76-92%) for the total population, 97% (95% CI 93-100%) for pts with a path response and 36% (95% CI 17-74%) for pts without a path response. Estimated 24-months EFS for the total population was 82% (95% CI 74-91%). RFS and EFS did not differ between the arms. Of the 81 pts alive, 55 (68%) have ongoing irAEs; only 2 (3%) pts have ≥ grade 3 irAEs. Most frequent ongoing irAEs were vitiligo (35%), fatigue (14%), sicca syndrome (11%), rash (10%), arthralgia (7%) and endocrine toxicities (20%). 17 pts need hormone replacement therapy: 11 (14%) thyroid hormone and 7 (9%) hydrocortisone. No difference between treatment arms was observed. Ongoing surgery-related AEs were observed in 31 (38%) pts of which lymphedema was seen most frequently (17 pts; 21%). Conclusions: Extended follow-up data shows that 2 cycles of neoadjuvant IPI + NIVO without adjuvant therapy induces durable RFS. While almost no ongoing high-grade irAEs were observed, the majority of pts have low-grade ongoing toxicities. These outcomes strongly support the need to test 2 cycles of neoadjuvant IPI1+NIVO3 versus adjuvant anti-PD-1 in a randomized phase 3 trial. Clinical trial information: NCT02977052.

TPS10087 Background: Previous OpACIN and OpACIN-neo studies, investigating neoadjuvant ipilimumab (IPI) plus nivolumab (NIVO), demonstrated high pathologic response rates (74-78%) and favorable long-term outcomes in patients (pts) achieving pathologic response; at 36 and 18 months follow-up, respectively, only 1/71 (1.4%) pts with response has relapsed. In contrast, pts without pathologic response (pNR) have a poor prognosis; 15/23 (65.2%) have relapsed so far. This emphasizes the need for baseline biomarkers predictive of non-response and new neoadjuvant treatment combinations for these pts. In our previous studies, baseline interferon-gamma (IFN-γ) signature low pts were less likely to respond to neoadjuvant IPI plus NIVO. The DONIMI study tests the combination of NIVO +/- IPI with domatinostat (DOM), a class 1 histone deacetylase inhibitor, according to the IFN-γ signature in the tumor. Based on the signature previously described by Ayers et al. we have developed a neoadjuvant IFN-γ signature algorithm that will be used for the first time to classify pts in this prospective trial. Methods: The aim of this two-center investigator-initiated phase 1b study is to assess the safety and feasibility of neoadjuvant NIVO +/- DOM +/- IPI in 45 stage III melanoma pts with RECIST 1.1 measurable de-novo or recurrent disease. IFN-γ signature high pts (n = 20) will be randomized (stratified by center) to Arm A (2 cycles NIVO 240mg q3wk) or Arm B (2 cycles NIVO 240mg q3wk + DOM 200mg twice daily (BID), d1-14, q3wk). IFN-γ signature low pts (n = 25) will be randomized to Arm C (2 cycles NIVO 240mg q3wk + DOM 200mg BID, d1-14, q3wk) or Arm D (2 cycles NIVO 240mg q3wk + IPI 80mg q3wk + DOM 200mg once daily (OD), d1-14, q3wk). Based on safety data of the first 5 pts in arm D, the remaining pts will be treated with either a higher dosing scheme (200mg BID, d1-14, q3wks), a lower dosing scheme (100mg OD, d1-14, q3wks) or the same dosing scheme (200mg OD, d1-14, q3wks). The primary endpoint is safety and feasibility. A treatment arm will be declared as not feasible if 2/5 or 3/10 pts cannot adhere to the preplanned time of surgery (week 6 +/- 1week) due to treatment-related adverse events. Biopsies (week 0, 3), blood samples (week 0, 3, 6, 12) and feces (week 0, 3, 6) will be collected for translational research. The first patient was enrolled on January 23th, 2020. Clinical trial information: NCT04133948.

e22096 Background: Large randomized trials have proved that targeted therapy (TT) and immunotherapy (IT) can improve RFS for resectable Stage III melanoma. However, there is still a risk around 15%~25% of relapse within 1 year, especially worse for Stage IIID disease. Several neoadjuvant trials have shown a potentiality of long-term relapse-free after a pathologic complete response, especially for immunotherapy. We conducted a prospective study to investigate the impact of preoperative treatment on the anti-tumor efficacy and disease-free survival for Chinese melanoma. Methods: Stage IIID patients with matted nodes were recruited. For BRAF V600E-muted patients, Vemurafenib (V) was given for one months ahead of the surgery. For BRAF-wide-type patients, anti-PD1 antibody, Pembrolizumab(P) or Toripalimab (T) was given one dose per 3 weeks until response or intention-to-progression was observed. Pathologic assessment followed the principles for neoadjuvant therapy established by INMC. Results: Totally seven patients have been recruited. Detail information was listed in Table. Clinical ORR was 71%, however with no pCR observed. One patient in Vemurafenib group occurred brain mets within 1 month after surgery. All four patients in anti-PD1 group were relapse-free so far after median follow-up of 11 months. Conclusions: Preoperative BRAF targeted and anti-PD1 immunotherapy might guarantee a positive impact on anti-tumor response and local disease control for marginally resectable melanoma. However, the pathological criteria for neoadjuvant treatment might not be suitable to evaluate the matted or bulky specimen after preoperative treatment. [Table: see text]

10064 Background: Neoadjuvant ipilimumab and nivolumab induces high pathologic response rates of 74-78% (OpACIN and OpACIN-neo trial), thus the role of Therapeutic Lymph Node Dissections (TLND) in patients with major pathologic responses (MPR: pathological (near) complete response) is now unclear. In the PRADO trial, TLND was omitted in patients with MPR in their index lymph node ((ILN), the largest LN marked prior to neoadjuvant therapy). We sought to determine if less extensive surgery is associated with better Health Related Quality of Life (HRQoL). These are the first results of the comparison of HRQoL between patients undergoing a TLND or less extensive ILN excision. Methods: HRQoL was assessed with the European Organisation for Research and Treatment of Cancer QoL questionnaire-C30 (QLQ-C30). A generalized estimation equation was used to assess the difference in HRQoL outcomes between patients who underwent TLND (pathological non- and partial-responders, pNR/pPR) versus those who did not (pathological (near)complete responders, pNCR/pCR). Differences were adjusted for age, gender and follow-up (FU, in weeks), but not for pathological responses (pNR, pPR, pNCR & pCR). Differences in QLQ-C30 scores were classified as clinically important according to published guidelines. Results: A total of 49 patients from the PRADO study had reached at least 24 weeks FU, and were included in the first explorative analysis. The median age of this study population was 58 years (range, 22-84). Questionnaire completion rates were high: 94% at baseline, 100%, 90%, 88% at week 6, 12 and 24, respectively. Sixteen (33%) patients underwent TLND versus 33 (67%) who had ILN excision only. Over a FU period of 24 weeks, patients who underwent TLND scored significantly lower on global (68 vs 78, adjusted difference (diff) = -9.53, p = .005), physical (84 vs 94 diff = -11.1, p = < .001), emotional (69 vs 83, diff = -11.7, p = .001), role (70 vs 85, diff = -13, p = .004), and social functioning (81 vs 91, diff = -8.9, p = .016) and had a higher symptom burden of fatigue (35 vs 23, diff = 11.1, p = .004), insomnia (38 vs 18, diff = 16.6, p = .002) and financial impact (12 vs 4, diff = 7.9, p = .027) than patients undergoing ILN excision only. These differences were indicated as clinically relevant. Conclusions: First results from PRADO suggest that reducing the extent of surgery following neoadjuvant immunotherapy might result in better HRQoL of high-risk stage III melanoma patients. Clinical trial information: NCT02977052.

e22088 Background: In recent years, adjuvant therapy trials in stage III melanoma have been successful and trials have started with the inclusion of stage IIB/C patients. However, stage IIA melanoma patients are currently not eligible for adjuvant therapy, even though a large part of all melanoma related deaths occur in this patient group. Therefore, a strong clinical need has emerged for diagnostic tools that can identify high-risk patients who currently have no access to adjuvant therapy. Here, we sought to assess the ability of a recently introduced clinicopathologic gene expression model (CP-GEP) (Bellomo et al., JCO Precis Oncol. 2020: in press) to select stage IIA patients at high risk for disease relapse, upon design of a stage-specific operating point. Methods: We assessed the prognostic performance of the CP-GEP model in all 141 stage IIA patients from a Mayo Clinic cohort of 837 consecutive melanoma patients who had a sentinel lymph node biopsy (SLNb) performed within 90 days of their diagnosis. The CP-GEP model combines Breslow thickness and patient age, with the expression of 8 genes in the primary tumor. Moreover, it stratifies patients according to their risk of relapse: CP-GEP High Risk or CP-GEP Low Risk, based on an operating point that was specifically developed for stage IIA. This stage-specific operating point was selected to fulfill the following criteria: hazard ratio RFS > 2 with a p-value < 0.05, and risk groups of similar size. The main clinical endpoint was five-year relapse free survival (RFS). Results: The CP-GEP High Risk group corresponds to 45% (63/141) of all stage IIA patients and captures 62% (18/29) of the total relapses in this substage. Moreover, CP-GEP High Risk patients relapse more frequently than CP-GEP Low Risk patients (RFS of 56% versus 78%; HR, 2.23; P < 0.05). The prognosis for stage IIA CP-GEP High Risk patients in our cohort is worse than for stage IIC/IIIA patients with reported RFS ranging from 63% to 77%. Conclusions: The CP-GEP model can be optimized by designing a stage-specific operating point, to identify a subset of stage IIA patients with an increased risk for disease relapse, not very different from IIC/IIIA patients. Therefore, stage IIA CP-GEP High Risk patients may be considered for inclusion in adjuvant trials. Independent validation studies are ongoing for the newly developed operating point. [Table: see text]

e22039 Background: To date, international consensus concerning the use of PET/CT as a surveillance tool in the follow-up of high-risk melanoma patients after complete resection of disease is lacking. Moreover, with the rise of adjuvant therapy it seems appropriate to investigate the role of this imaging modality to exclude newly developed metastases after resection and prior to starting treatment. The aim of this study was to investigate the use of PET/CT as surveillance tool in the follow-up and prior to adjuvant therapy in asymptomatic patients with complete resection of stage IIIB and IIIC melanoma. Methods: Prospectively two cohorts were set up with stage III melanoma patients with complete resection of disease. In the first cohort (stage IIIB/C AJCC 7th) surveillance PET/CT was performed 6-monthly for two years if patients stayed asymptomatic with normal serum S100B, with a final scan at three years. In the second cohort (stage IIIB/C/D AJCC 8th) patients underwent one screening PET/CT after resection and prior to starting adjuvant treatment. Results: Eighty patients entered follow-up in cohort 1. Of these, the majority did not undergo surveillance scans, because they required treatment for newly detected clinical metastases. Thirty-five patients remained asymptomatic and were included in surveillance cohort one (105 scans) with a median follow-up of 33 months. Twelve patients (34%) developed a recurrence, seven (20%) of which were detected on the first scan at six months. Seven recurrences involved stage IIIC patients, five stage IIIB patients. Sensitivity and specificity were 92% and 100% respectively. Forty-two patients were included in cohort 2. Recurrence was suspected on nine scans, four (10%) of which were true positive. One patient proceeded to undergo a node dissection and then started adjuvant therapy. The other three patients had progressed to stage IV and therefore started radiotherapy and/or systemic immunotherapy. Five (12%) scans were false positive, the suspected lesions were not related to the preceded surgery. The number of scans needed to find one asymptomatic recurrence were 8.8 and 10.5 in cohort one and two, respectively. Conclusions: This study shows that PET/CT is a useful surveillance tool for detecting recurrence in asymptomatic high-risk resected stage III melanoma patients, especially within the first six months after surgery and therefore should be considered when monitoring these patients during follow-up as well as prior to starting adjuvant therapy.

9582 Background: In the COMBI-AD trial (NCT01682083), 12 mo of adjuvant D+T led to significant improvement of RFS vs PBO (hazard ratio [HR], 0.47; P < .001) in pts with resected BRAF V600–mutant stage III melanoma; 3- and 4-year RFS rates were 59% and 54%, respectively. Previous results demonstrated consistent treatment benefit across baseline disease stage according to AJCC edition 7 or 8. Here, we further explored the association between baseline disease characteristics and RFS to identify pt subgroups likely to benefit from adjuvant treatment. Methods: Randomized pts with completely resected BRAF V600E/K–mutant stage III melanoma received 12 mo of adjuvant D (150 mg BID) + T (2 mg QD) or PBO. Within each subgroup, predictive value was explored using Kaplan-Meier analysis, and HRs were calculated using a Pike estimator. Results: Minimum follow-up was 40 mo for 870 enrolled pts (D+T, 438; PBO, 432). Kaplan-Meier analysis demonstrated treatment benefit across all subgroups analyzed. Assessment of RFS by extent of primary tumor (T stage) showed consistent benefit favoring D+T vs PBO (HR [95% CI]; T1, 0.42 [0.25-0.70]; T2, 0.51 [0.34-0.76]; T3, 0.55 [0.39-0.77]; T4, 0.42 [0.29-0.60]). HRs by nodal burden (N stage) also showed consistent treatment benefit (N1, 0.52 [95% CI, 0.37-0.72]; N2, 0.38 [95% CI, 0.28-0.53]; N3, 0.58 [95% CI, 0.41-0.83]). Substantial treatment benefit was observed in pts with baseline in-transit metastases (HR, 0.45 [95% CI, 0.24-0.82]) and those with no in-transit metastases detected at baseline (HR, 0.49 [95% CI, 0.40-0.60]). When RFS was assessed according to melanoma presentation, treatment benefit favoring D+T vs PBO was observed in pts with superficial spreading melanoma (HR, 0.48 [95% CI, 0.35-0.66]) and those with nodular melanoma (HR, 0.53 [95% CI, 0.37-0.75]). Conclusions: These results confirm earlier findings showing that treatment benefit with adjuvant D+T vs PBO is independent of baseline factors. Clinical trial information: NCT01682083.

Objective: To determine the efficacy of pembrolizumab relative to other treatments used in stage III melanoma by conducting a systematic literature review (SLR) and network meta-analysis (NMA). Methods: A SLR was conducted to identify randomized clinical trials (RCTs) evaluating approved adjuvant treatments including interferon-containing regimens, BRAF-inhibitors, and PD-L1 inhibitors in stage III melanoma patients. Relative treatment effects for recurrence-free survival (RFS) were synthesized with Bayesian NMA models that allowed for hazard ratios (HRs) to vary over time. Results: Included studies formed a connected network of evidence composed of eight trials. In high-risk stage III patients, the HR for pembrolizumab vs observation decreased significantly over time with the superiority of pembrolizumab over observation becoming statistically meaningful before 3 months. By 9 months, the HR for pembrolizumab vs observation was statistically significantly lower than the HR for most other treatments vs observation, with the exception of ipilimumab and biochemotherapy due to overlapping 95% credible intervals. In BRAF + patients, pembrolizumab was statistically significantly better than observation after 3 months. The HR for both BRAF-inhibitors vs observation increased significantly over time and pembrolizumab was statistically superior to both BRAF-inhibitors after 15 months. Conclusions: Pembrolizumab results in statistically significantly improved RFS compared to all competing regimens after 9 months, except ipilimumab and biochemotherapy, for the adjuvant treatment of stage III melanoma. However, point estimate HRs vs observation for pembrolizumab are much lower than those for ipilimumab. In BRAF + patients, the advantage of pembrolizumab versus competing interventions increases over time with respect to RFS.

International audience; Les résultats des études sur le ganglion sentinelle et des essais de thérapies ciblées ou d’immunothérapie en situation adjuvante dans le mélanome ont rendu indispensable une actualisation des recommandations de prise en charge des mélanomes de stade III. À la demande du Groupe de cancérologie cutanée de la Société française de dermatologie, une actualisation a donc été réalisée en utilisant les méthodes classiques d’analyse de la littérature selon les principes de la médecine fondée sur les preuves.