Citations

9568 Background: Stage IIB/C cutaneous melanoma is associated with high recurrence risk, however stratification of risk in relation to time after surgery has not been comprehensively evaluated. We evaluated recurrence-free survival (RFS) at key time points, stratified by clinicopathologic factors, to identify patients (pts) at higher recurrence risk and personalize postoperative surveillance strategies. Methods: In this multi-institutional, international retrospective cohort study from the Sentinel Lymph Node Working Group database, we included pts with pathologic T3b/T4a/T4b and N0 disease who underwent surgical resection and sentinel node biopsy from 1994-2025. The type of first recurrence (local, regional, distant) was characterized based on time category (0-12, 12-24, 24-60, and 60+ months after surgery). Restricted mean survival time (RMST) analysis was used to measure the average survival time up to a specified time point (6-, 12-, 24-, and 60-months after surgery), and associations of clinicopathologic variables (age, sex, Breslow thickness, ulceration and lymphovascular invasion [LVI]) with RFS. Results: We included 2514 stage IIB/C pts from 19 sites in 4 countries, with a median follow-up of 53 (stage IIB) and 49 (stage IIC) months. 675 (27%) pts experienced a recurrence (92 [14%] local, 238 [35%] regional and 345 [51%] distant), and 400 (59%) recurrences occurred within 24 months. The proportion of distant recurrences as the first recurrence increased significantly with time, comprising 39%, 50%, 62%, and 59% of recurrences in the 0-12, 12-24, 24-60, and 60+ month time categories respectively (χ 2 p<0.001). No significant differences were observed for the included clinicopathologic variables for 6-month RMST estimates. At 12 months, RMST estimates for thickness ≥4 mm (11.2 vs 11.6 months for thickness 2-3.99 mm, p<0.001) and presence of LVI (10.7 vs 11.4 months, p=0.009) were significantly different. 24-month RMST estimates differed for male sex (20.7 vs 21.5 months vs females, p=0.002), thickness ≥4 mm (20.5 vs 21.9 months, p<0.001), and presence of LVI (19.0 vs 21.1 months, p<0.001). Lastly, 60-month RMST estimates differed for male sex (42.0 vs 45.2 months, p=0.001), thickness ≥4 mm (41.5 vs 46.2 months, p<0.001), LVI (36.0 vs 43.7 months, p<0.001), and age >65 years (41.5 vs 46.4 for age <42, p=0.022). Conclusions: In this real-world, multi-center analysis of pathologic stage IIB/C melanoma pts, recurrence patterns varied based on time after surgery. Breslow thickness, LVI, male sex, and age were significantly associated with earlier recurrence at different time intervals on RMST analysis. Additionally, given that >50% of first recurrences 12+ months after surgery were distant, active surveillance for distant relapses may be warranted.

9524 Background: Unresectable melanoma in-transit metastases (ITM) can pose a significant clinical challenge. Our recently published data comparing first-line treatments for ITM, isolated limb infusion or perfusion (ILI/ILP), immune checkpoint inhibitors (ICI) and intralesional talimogene laherparepvec (TVEC), found superior outcomes with TVEC. However, TVEC was used more often in patients with lower disease burden and earlier stage (IIIB vs. IIIC/D). Therefore, we sought to better investigate these differences with a propensity score-matched (PSM) analysis. Methods: A multi-institutional, international IRB- approved retrospective analysis was conducted for unresectable melanoma ITM from 2016-2022. PSM analysis comparing first-line ILI/ILP, ICI, and TVEC for was performed. Patients were matched for stage, number of ITM, anatomical site, CLND status, gender and age. Kaplan-Meier curves (OS, PFS, DMFS) and Cumulative incidence function (MSS) were used to visualize time-to-event outcomes in the PSM cohort, though both methods do not account for the matched structure. Results: 274 patients were identified, 120 female/154 male; 96 treated with ILI/ILP, 111 with ICI, and 67 with TVEC. Median follow-up was 40 months (range, 1-80). PSM was performed and identified 36 TVEC–ICI pairs and 27 TVEC–ILI pairs. These were combined resulting in a final cohort of 108 observations (45 TVEC, 36 ICI and 27 ILI). The groups were well balanced. No statistical difference was found for metastasis-free survival (DMFS), progression-free survival (PFS), melanoma-specific survival (MSS), and overall survival (OS) between treatment modalities. TVEC was associated with significant improvement in local PFS (median was 2.2 years (y) for ILI/ILP, 1.5y for ICI and not reached for TVEC, p=0.048). While not statistically significant, a clinical benefit was seen in PFS being longer for TVEC (2.1y for TVEC vs. 1.2y for ILI/ILP and 1.1y for ICI; p=0.2) and OS (not reached vs 2.9y for ILI/ILP and 5.2y for ICI; p=0.2). On mixed effect Cox regression proportional hazard model using the matched data set, there were no significant differences in any of the survival and recurrence outcomes. Conclusions: When patients are propensity-matched, there were no significant differences in first-line treatment modalities for unresectable melanoma ITM. Treatment with TVEC did result in clinically meaningful improved overall and local PFS and OS. This supports that selection of ITM therapy should incorporate an individualized approach, incorporating disease distribution, stage, burden, treatment side effects and patient priorities.

Abstract Background Recently, a model to predict 5-year recurrence-free survival (RFS) and melanoma-specific survival (MSS) after sentinel lymph node biopsy (SLNB) was published. The aim of this study was to validate that model in a large independent international cohort. Methods The database of the Sentinel Lymph Node Working Group (SLNWG) was analysed for patients with malignant melanoma who underwent SLNB. Patients with clinical stage III melanoma, a history of other malignancies, or receiving concomitant systemic therapies during follow-up were excluded. The model’s predictive performance was evaluated using discrimination and calibration metrics in the eligible cohort. Decision curve analysis was performed to assess the clinical value of the model. Results The external validation cohort consisted of 6174 patients of the SLNWG from the USA, Europe, and Israel. A positive sentinel node was found in 788 patients (12.8%). The area under the time-dependent receiver operating characteristic (ROC) curve of the external validation was 0.76 (95% c.i. 0.74 to 0.77) for RFS and 0.79 (95% c.i. 0.76 to 0.81) for MSS. The model was well calibrated, as the observed 5-year survival rates aligned closely with the predicted survival rates (calibration slope of 0.98 for RFS and calibration slope of 0.99 for MSS). The model provided a net benefit versus the ‘treat all’ and ‘treat none’ strategies at the predetermined probability threshold for recurrence of 45%. Conclusion The model demonstrated good performance in a large heterogeneous independent cohort, emphasizing its robustness. Decision curve analysis revealed a clear net benefit of the model over a treat all strategy, highlighting its potential for clinical use.

AbstractBackgroundIsolated limb infusion and perfusion (ILI/ILP) has been a mainstay treatment for unresectable melanoma in‐transit metastases (ITM), but increased use of immune checkpoint inhibitors (ICI) and intralesional therapy (talimogene laherparepvec [TVEC]) introduced several different management options. This study compares first‐line ILI/ILP, ICI, and TVEC.MethodsRetrospective review from 12 international institutions included patients treated from 1990 to 2022 with first‐line ILI/ILP, ICI, or TVEC for unresectable melanoma ITM.ResultsA total of 551 patients were treated, with ILI/ILP (n = 356), ICI (n = 125), and TVEC (n = 70) with median follow‐up of 5.5 years. Tumor burden was highest with ILI/ILP and lowest with TVEC (p = .002). Breslow thickness was lowest with TVEC (p = .007). TVEC was mostly used in stage IIIB disease versus IIIC for ILI/ILP and ICI (p = .01). Using ICI as the reference category, TVEC had the highest odds of a complete response (CR) (odds ratio, 1.96; p = .029) and a longer local progression‐free survival (PFS) (hazard ratio [HR], 0.40; p = .003). ILI/ILP had shorter local PFS (HR, 1.72; p = .012), PFS (HR, 1.79; p < .001), distant metastasis‐free survival (DMFS) (HR, 1.75; p = .014), overall survival (HR, 1.82; p = .009), and melanoma‐specific survival (HR, 2.29; p = .004). Stage IIIB disease had longer DMFS (HR, 0.24; p < .001) compared to IIIC/D.ConclusionsTVEC as first‐line therapy for unresectable melanoma ITM was associated with superior CR rates and local PFS. Notably, TVEC was used in patients with a lower Breslow thickness, disease stage, and tumor burden. Therefore, when compared to ILI/ILP and ICI, TVEC should be considered as first‐line therapy for unresectable stage IIIB melanoma ITM with minimal tumor burden and lower Breslow thickness.

9574 Background: Surgery remains the gold standard for resectable melanoma in-transit metastases (ITM). Unresectable ITM is a heterogenous disease with multiple treatment (tx) options including systemic therapies such as immune checkpoint inhibitors (ICI), regional therapies such as isolated limb infusion or perfusion (ILI/P), and intratumoral therapies such as talimogene laherparepvec (IT). Until now, there has been no direct comparison of these first-line tx for unresectable ITM. Methods: A retrospective chart review of patients (pts) with ITM treated first-line with IT, ILI/P, or ICI was performed at 11 institutions. Pts with unresectable ITM, synchronous nodal or distant metastatic disease were excluded. Results: 560 pts (54% women) were identified, 86 received IT, 353 received ILI/P, and 121 received ICI from 1990-2022. ICI pts were youngest, IT pts were oldest (p<0.001). Limb was the most common site of ITM. There was no difference in largest ITM size, but number of lesions (burden of disease (BOD)) was highest in ILI/P pts and lowest in IT pts (p=0.003). Toxicity (tox) requiring <90 days (p<0.001) or > 90 days (p=0.034) of pharmacologic tx as well as tox requiring hospitalization (p<0.001) was greatest in ICI pts. Lymphedema was more likely in ILI/P pts (p=0.016). Median follow-up was much longer for ILI/P pts at 8.0 yrs compared to 2.5 yrs for IT pts and 3.1 yrs for ICI pts. Overall response rate (ORR) was 82.2% in ILI/P pts, significantly higher than IT (72.1%, p=0.047) or ICI pts (63.6%, p<0.001). Overall survival was similar between modalities (p=0.167); however, ILI/P pts had worse progression-free survival (PFS) (p<0.0001) and melanoma-specific survival (MSS) (p=0.003). On multivariable analysis of MSS by number of ITM present, MSS remained worst if ILI/P was used for low BOD, ≤3 ITM (p=0.005), but no difference was seen between tx modalities for higher BOD, >3 ITM (p=0.211). Conclusions: ICI was used more often in younger pts with less BOD, IT in older pts with less BOD, and ILI/P in older pts with high BOD. Short and long-term tox was greater in ICI. ILI/P had the best ORR, but ICI and IT resulted in greater overall MSS. Multidisciplinary consideration of risks and benefits of each modality should guide ITM tx selection. [Table: see text]

Until recently, most patients with sentinel lymph node-positive (SLN+) melanoma underwent a completion lymph node dissection (CLND), as mandated in published trials of adjuvant systemic therapies. Following multicenter selective lymphadenectomy trial-II, most patients with SLN+ melanoma no longer undergo a CLND prior to adjuvant systemic therapy. A retrospective analysis of clinical outcomes in SLN+ melanoma patients treated with adjuvant systemic therapy after July 2017 was performed in 21 international cancer centers. Of 462 patients who received systemic adjuvant therapy, 326 patients received adjuvant anti-PD-1 without prior immediate (IM) CLND, while 60 underwent IM CLND. With median follow-up of 21 months, 24-month relapse-free survival (RFS) was 67% (95% CI 62% to 73%) in the 326 patients. When the patient subgroups who would have been eligible for the two adjuvant anti-PD-1 clinical trials mandating IM CLND were analyzed separately, 24-month RFS rates were 64%, very similar to the RFS rates from those studies. Of these no-CLND patients, those with SLN tumor deposit >1 mm, stage IIIC/D and ulcerated primary had worse RFS. Of the patients who relapsed on adjuvant anti-PD-1, those without IM CLND had a higher rate of relapse in the regional nodal basin than those with IM CLND (46% vs 11%). Therefore, 55% of patients who relapsed without prior CLND underwent surgery including therapeutic lymph node dissection (TLND), with 30% relapsing a second time; there was no difference in subsequent relapse between patients who received observation vs secondary adjuvant therapy. Despite the increased frequency of nodal relapses, adjuvant anti-PD-1 therapy may be as effective in SLN+ pts who forego IM CLND and salvage surgery with TLND at relapse may be a viable option for these patients.

9569 Background: Guidelines addressing melanoma in-transit metastasis (ITM) recommend immune checkpoint inhibitors (ICI) as a first-line treatment option, despite the fact that there are no efficacy data available from prospective trials for exclusively ITM disease. The aim of this study was to analyze the outcome of patients with ITM treated with ICI based on data from a large cohort of patients treated at international high‐volume melanoma centers. Methods: A multicenter retrospective cohort study of patients treated between January 2015 and December 2020 from Australia, Europe, and USA, evaluating treatment with ICI for ITM with or without nodal involvement (AJCC8 N1c, N2c and N3c) and without distant disease (M0). Patients were treated with PD-1 inhibitor (nivolumab or pembrolizumab) and/or CTLA-4 inhibitor (ipilimumab). We assessed response rates, progression-free survival (PFS), melanoma-specific survival (MSS) and overall survival (OS). Results: A total of 287 patients from 21 institutions in 8 countries were included. Immunotherapy was first-line treatment in 64 (22%) patients. Monotherapy with a PD-1 or CTLA-4 inhibitor was given in 233 (81%) and 23 (8%) patients respectively, while 31 (11%) received both in combination. Overall response rate was 56%, complete response (CR) rate 36% and progressive disease (PD) rate 32%. Median PFS was 10 months (95% CI 7.4-12.6 months) with a 1-, 2- and 5-year PFS rate of 48%, 33% and 18% respectively. Median MSS was not reached, and the 1-, 2- and 5-year MSS rates were 95%, 83% and 71% respectively. Conclusions: Systemic immunotherapy is an effective treatment for melanoma ITM. Future studies should evaluate the optimal role for systemic immunotherapy in the context of multimodality therapy including locoregional treatments such as surgery, intralesional therapy, and regional therapies.

Objective: The aim of this study was to determine overall trends and center-level variation in utilization of completion lymph node dissection (CLND) and adjuvant systemic therapy for sentinel lymph node (SLN)-positive melanoma. Summary Background Data: Based on recent clinical trials, management options for SLN-positive melanoma now include effective adjuvant systemic therapy and nodal observation instead of CLND. It is unknown how these findings have shaped practice or how these contemporaneous developments have influenced their respective utilization. Methods: We performed an international cohort study at 21 melanoma referral centers in Australia, Europe, and the United States that treated adults with SLN-positive melanoma and negative distant staging from July 2017 to June 2019. We used generalized linear and multinomial logistic regression models with random intercepts for each center to assess center-level variation in CLND and adjuvant systemic treatment, adjusting for patient and disease-specific characteristics. Results: Among 1109 patients, performance of CLND decreased from 28% to 8% and adjuvant systemic therapy use increased from 29 to 60%. For both CLND and adjuvant systemic treatment, the most influential factors were nodal tumor size, stage, and location of treating center. There was notable variation among treating centers in management of stage IIIA patients and use of CLND with adjuvant systemic therapy versus nodal observation alone for similar risk patients. Conclusions: There has been an overall decline in CLND and simultaneous adoption of adjuvant systemic therapy for patients with SLN-positive melanoma though wide variation in practice remains. Accounting for differences in patient mix, location of care contributed significantly to the observed variation.

BackgroundFor patients with sentinel lymph node (SLN)‐positive cutaneous melanoma, the Second Multicenter Selective Lymphadenectomy trial demonstrated equivalent disease‐specific survival (DSS) with active surveillance using nodal ultrasound versus completion lymph node dissection (CLND). Adoption and outcomes of active surveillance in clinical practice and in adjuvant therapy recipients are unknown.MethodsIn a retrospective cohort of SLN‐positive adults treated at 21 institutions in Australia, Europe, and the United States from June 2017 to November 2019, the authors evaluated the impact of active surveillance and adjuvant therapy on all‐site recurrence‐free survival (RFS), isolated nodal RFS, distant metastasis‐free survival (DMFS), and DSS using Kaplan‐Meier curves and Cox proportional hazard models.ResultsAmong 6347 SLN biopsies, 1154 (18%) were positive and had initial negative distant staging. In total, 965 patients (84%) received active surveillance, 189 (16%) underwent CLND. Four hundred thirty‐nine patients received adjuvant therapy (surveillance, 38%; CLND, 39%), with the majority (83%) receiving anti–PD‐1 immunotherapy. After a median follow‐up of 11 months, 220 patients developed recurrent disease (surveillance, 19%; CLND, 22%), and 24 died of melanoma (surveillance, 2%; CLND, 4%). Sixty‐eight patients had an isolated nodal recurrence (surveillance, 6%; CLND, 4%). In patients who received adjuvant treatment without undergoing prior CLND, all isolated nodal recurrences were resectable. On risk‐adjusted multivariable analyses, CLND was associated with improved isolated nodal RFS (hazard ratio [HR], 0.36; 95% CI, 0.15‐0.88), but not all‐site RFS (HR, 0.68; 95% CI, 0.45‐1.02). Adjuvant therapy improved all‐site RFS (HR, 0.52; 95% CI, 0.47‐0.57). DSS and DMFS did not differ by nodal management or adjuvant treatment.ConclusionsActive surveillance has been adopted for most SLN‐positive patients. At initial assessment, real‐world outcomes align with randomized trial findings, including in adjuvant therapy recipients.Lay Summary For patients with melanoma of the skin and microscopic spread to lymph nodes, monitoring with ultrasound is an alternative to surgically removing the remaining lymph nodes. The authors studied adoption and real‐world outcomes of ultrasound monitoring in over 1000 patients treated at 21 centers worldwide, finding that most patients now have ultrasounds instead of surgery. Although slightly more patients have cancer return in the lymph nodes with this strategy, typically, it can be removed with delayed surgery. Compared with up‐front surgery, ultrasound monitoring results in the same overall risk of melanoma coming back at any location or of dying from melanoma.