The difficulty with measuring the largest melanoma tumour diameter in sentinel lymph nodes

Identification of sentinel node (SN) metastases can set the adjuvant systemic therapy indication for stage III melanoma patients. For stage IIIA patients, a 1.0 mm threshold for the largest SN tumour diameter is used. Therefore, uniform reproducible measurement of its size is crucial. At present, the number of deposits or their microanatomical sites are not part of the inclusion criteria for adjuvant treatment. The goal of the current study was to show examples of the difficulty of measuring SN melanoma tumour diameter and teach how it should be measured. Histopathological slides of SN-positive melanoma patients were retrieved using the Dutch Pathology Registry (PALGA). Fourteen samples with the largest SN metastasis around 1.0 mm were uploaded via tele-pathology and digitally measured by 12 pathologists to reflect current practice of measurements in challenging cases. Recommendations as educational examples were provided. Microanatomical location of melanoma metastases was 1 subcapsular, 2 parenchymal and 11 combined. The smallest and largest difference in measurements were 0.24 mm and 4.81 mm, respectively. 11/14 cases (78.6%) showed no agreement regarding the 1.0 mm cut-off. The median discrepancy for cases ≤5 deposits was 0.5 mm (range 0.24-0.60, n=3) and 2.51 mm (range 0.71-4.81, n=11) for cases with ≥6 deposits. Disconcordance in measuring SN tumour burden is correlated with the number of deposits. Awareness of this discordance in challenging cases, for example, cases with multiple small deposits, is important for clinical management. Illustrating cases to reduce differences in size measurement are provided.

The limited value of sentinel lymph node biopsy in lentigo maligna melanoma: A nomogram based on the results of 29 years of the nationwide dutch pathology registry (PALGA)

BACKGROUND

Lentigo maligna melanoma (LMM) predominantly presents in the head and neck of the elderly. The value of sentinel lymph node biopsy (SLNB) for LMM patients remains to be determined, as the reported average yield of positive lymph nodes is less than 10%. In this nationwide cohort study, we wanted to identify LMM patients with an increased risk of SLNB-positivity.

METHODS

LMM with an SLNB indication according to the 8th AJCC melanoma guidelines were retrospectively identified from the nationwide network and registry of histo- and cytopathology in the Netherlands (PALGA). A penalized (LASSO) logistic regression analysis was performed to determine the optimal combination of clinicopathological factors to predict a positive SLNB.

RESULTS

Between 1991 and 2020, 1989 LMM patients met our inclusion criteria. SLNB was performed in 16.7% (n = 333) and was positive in 7.5% (25/333). The false-negative rate was 21.9%. Clinically detectable regional lymph node (LN) metastases were found in 1.3% (n = 25). Clinicopathological characteristics best predictive for SLNB-positivity (Odds ratio; 95% CI) were age (0.95; 0.91-0.99), ulceration 1.59 (0.44-4.83), T4-stage (1.81; 0.43-6.2), male sex (1.97; 0.79-5.27), (lymph)angioinvasion (5.07; 0.94-23.31), and microsatellites (7.23; 1.56-32.7) (C-statistic 0.75). During follow-up, regional LN recurrences were detected in 4.2% (83/1989) of patients, of which the majority (74/83) had no evidence of regional LN metastases at baseline.

CONCLUSION

Our findings confirm the limited SLNB-positivity in LMM patients. Based on the identified high-risk clinicopathological features, a nomogram was developed to predict the risk of a positive SLNB.

IMPemBra: a phase 2 study comparing pembrolizumab with intermittent/short-term dual MAPK pathway inhibition plus pembrolizumab in patients with melanoma harboring the BRAFV600 mutation

BACKGROUND

Continuous combination of MAPK pathway inhibition (MAPKi) and anti-programmed death-(ligand) 1 (PD-(L)1) showed high response rates, but only limited improvement in progression-free survival (PFS) at the cost of a high frequency of treatment-related adverse events (TRAE) in patients with BRAF^V600-mutated melanoma. Short-term MAPKi induces T-cell infiltration in patients and is synergistic with anti-programmed death-1 (PD-1) in a preclinical melanoma mouse model. The aim of this phase 2b trial was to identify an optimal regimen of short-term MAPKi with dabrafenib plus trametinib in combination with pembrolizumab.

METHODS

Patients with treatment-naïve BRAF^V600E/K-mutant advanced melanoma started pembrolizumab 200 mg every 3 weeks. In week 6, patients were randomized to continue pembrolizumab only (cohort 1), or to receive, in addition, intermittent dabrafenib 150 mg two times per day plus trametinib 2 mg one time per day for two cycles of 1 week (cohort 2), two cycles of 2 weeks (cohort 3), or continuously for 6 weeks (cohort 4). All cohorts continued pembrolizumab for up to 2 years. Primary endpoints were safety and treatment-adherence. Secondary endpoints were objective response rate (ORR) at week 6, 12, 18 and PFS.

RESULTS

Between June 2016 and August 2018, 33 patients with advanced melanoma have been included and 32 were randomized. Grade 3-4 TRAE were observed in 12%, 12%, 50%, and 63% of patients in cohort 1, 2, 3, and 4, respectively. All planned targeted therapy was given in 88%, 63%, and 38% of patients in cohort 2, 3, and 4. ORR at week 6, 12, and 18 were 38%, 63%, and 63% in cohort 1; 25%, 63%, and 75% in cohort 2; 25%, 50%, and 75% in cohort 3; and 0%, 63%, and 50% in cohort 4. After a median follow-up of 43.5 months, median PFS was 10.6 months for pembrolizumab monotherapy and not reached for patients treated with pembrolizumab and intermittent dabrafenib and trametinib (p=0.17). The 2-year and 3-year landmark PFS were both 25% for cohort 1, both 63% for cohort 2, 50% and 38% for cohort 3 and 75% and 60% for cohort 4.

CONCLUSIONS

The combination of pembrolizumab plus intermittent dabrafenib and trametinib seems more feasible and tolerable than continuous triple therapy. The efficacy is promising and appears to be favorable over pembrolizumab monotherapy.

TRIAL REGISTRATION NUMBER

NCT02625337.

IFN-γ signature enables selection of neoadjuvant treatment in patients with stage III melanoma

Neoadjuvant ipilimumab + nivolumab has demonstrated high pathologic response rates in stage III melanoma. Patients with low intra-tumoral interferon-γ (IFN-γ) signatures are less likely to benefit. We show that domatinostat (a class I histone deacetylase inhibitor) addition to anti-PD-1 + anti-CTLA-4 increased the IFN-γ response and reduced tumor growth in our murine melanoma model, rationalizing evaluation in patients. To stratify patients into IFN-γ high and low cohorts, we developed a baseline IFN-γ signature expression algorithm, which was prospectively tested in the DONIMI trial. Patients with stage III melanoma and high intra-tumoral IFN-γ scores were randomized to neoadjuvant nivolumab or nivolumab + domatinostat, while patients with low IFN-γ scores received nivolumab + domatinostat or ipilimumab + nivolumab + domatinostat. Domatinostat addition to neoadjuvant nivolumab ± ipilimumab did not delay surgery but induced unexpected severe skin toxicity, hampering domatinostat dose escalation. At studied dose levels, domatinostat addition did not increase treatment efficacy. The baseline IFN-γ score adequately differentiated patients who were likely to benefit from nivolumab alone versus patients who require other therapies.

Talimogene laherparepvec monotherapy for head and neck melanoma patients

Talimogene laherparepvec (T-VEC) is a modified herpes simplex virus, type 1, intralesionally administered in patients with stage IIIB/C-IVM1a unresectable melanoma. When surgery is not a treatment option in the head and neck region, T-VEC can be an elegant alternative to systemic immunotherapy. Ten patients with metastatic melanoma in the head and neck region started treatment with T-VEC monotherapy at the Netherlands Cancer Institute. We collected data on response, adverse events (AEs), and baseline characteristics. For response evaluation, we used clinical evaluation with photography, 3-monthly PET/computed tomography (PET/CT) using 18F-fluoro-2-D-deoxyglucose, and histological biopsies. Median age at baseline was 78.2 (35-97) years with a median follow-up of 11.6months. Of these 10 patients, 5 had a complete response (CR), 3 had a partial response, 1 had stable disease and 1 showed progressive disease (PD) as their best response. Best overall response rate (ORR) was 80%. Median progression-free survival was 10.8 months (95% confidence interval, 2.2-19.4). Grade 1 AEs occurred in all patients. Mostly, these consisted of fatigue, influenza-like symptoms, and injection site pain. PET-CT and histological biopsies proved to be clinically useful tools to evaluate treatment response for T-VEC monotherapy, confirming pCR or PD to stage IV disease requiring systemic treatment. ORR for T-VEC monotherapy for melanoma in the head and neck region at our institute was 80% with 50% achieving a CR. This realworld data demonstrates promising results and suggests T-VEC can be an alternative to systemic therapy in this select, mostly elderly patient population.

Re-introduction of T-VEC Monotherapy in Recurrent Melanoma is Effective

Talimogene laherparepvec (T-VEC) is a modified herpes simplex virus type 1, which can be administered intralesionally in patients with stage IIIB/C-IVM1a (American Joint Committee of Cancer; AJCC 7th edition) unresectable melanoma. In the case of disease recurrence, T-VEC can be re-introduced for the same category of patients. Five patients with recurrent disease after a prior achieved complete response (CR) recommenced treatment with T-VEC monotherapy at the Netherlands Cancer Institute. We collected data on response, adverse events and baseline characteristics. All 5 patients that were re-treated with T-VEC presented with in-transit metastases on the lower limb. Median age at baseline was 72.1 years with a median follow-up time of 30.4 months. Histologically proven CR was achieved after a median of 8 T-VEC courses on the initial exposure. Duration of response (time between first CR and recurrence) varied between 3.8 and 14.2 months. All 5 patients achieved a histologically and/or positron emission tomography/computed tomography proven CR again after re-introduction of T-VEC with a median of 5 courses. One patient (20%) developed a second recurrence and is currently still on treatment with T-VEC. No patients developed distant metastases. Grade 1 adverse events occurred in all patients. Mostly, these consisted of fatigue, influenza-like symptoms and injection site pain. Response to re-introduction of T-VEC monotherapy in this select patient population is promising. This real world data on re-introduction of T-VEC monotherapy in stage IIIB/C-IVM1a melanoma suggests T-VEC could be a treatment option for chronic disease control.

18F-FDG PET/CT During Neoadjuvant Targeted Therapy in Prior Unresectable Stage III Melanoma Patients: Can (Early) Metabolic Imaging Predict Histopathologic Response or Recurrence?

PURPOSE

The aim of this study was to investigate whether 18F-FDG PET/CT can predict histopathological response or recurrence in BRAF-mutated unresectable locally advanced stage III melanoma treated with neoadjuvant BRAF/MEK inhibition followed by resection and the value of PET in detecting early recurrence after resection.

PATIENTS AND METHODS

Twenty BRAF-mutated, unresectable stage III melanoma patients received BRAF/MEK inhibitors before surgery. 18F-FDG PET/CT was performed at baseline and 2 and 8 weeks after initiation of therapy. After resection, PET/CT was performed at specific time points during 5 years of follow-up. Pathological response was assessed on the dissection specimen. Response monitoring was measured with SUVmax, SUVpeak, MATV, and TLG and according to EORTC and PERCIST criteria.

RESULTS

Pathological response was assessed in 18 patients. Nine patients (50%) had a pathologic complete or near-complete response, and 9 (50%) had a pathologic partial or no response. EORTC or PERCIST response measurements did not correspond with pathologic outcome. SUVmax, SUVpeak, MATV, and TLG at all time points and absolute or percentage change among the 3 initial time points did not differ between the groups.During follow-up, 8 of 17 patients with R0 resection developed a recurrence, 6 recurrences were detected with imaging only, 4 of which with PET/CT in less than 6 months after surgery. PET parameters before surgery did not predict recurrence.

CONCLUSIONS

Baseline 18F-FDG PET or PET response in previous unresectable stage III melanoma patients seems not useful to predict pathologic response after neoadjuvant BRAF/MEK inhibitors treatment. However, PET/CT seems valuable in detecting recurrence early after R0 resection.

The interferon-gamma (IFN-y) signature from baseline tumor material predicts pathologic response after neoadjuvant ipilimumab (IPI) + nivolumab (NIVO) in stage III melanoma

9539

Background: Neoadjuvant IPI + NIVO induces high pathologic response rates (pRR) of 74-78% in macroscopic stage III melanoma. Pathologic response ( < 50% viable tumor) is strongly associated with improved relapse-free survival (RFS); the previous OpACIN-neo study demonstrated a 2-year RFS of 96.9% in patients (pts) with pathologic response, whereas the 2-year RFS in non-responders was 35.5%. These data highlight the need for baseline biomarkers predictive for response and survival. Here, we present the predictive value of the 10-gene IFN-y expression signature algorithm (based on Ayers et al.) for pathologic response and relapse in a cohort of melanoma pts treated with neoadjuvant IPI + NIVO. Methods: Baseline tumor biopsies from lymph node metastases of stage III melanoma pts were used for IFN-y signature assessment. Pts were treated with a maximum of two cycles of neoadjuvant IPI 1mg/kg + NIVO 3mg/kg in the OpACIN-neo (arm B) and PRADO studies. RNA expression analysis was conducted using the nCounter® PanCancer Immune Profiling panel on the NanoString Flex machine (NanoString Technologies), which is clinically applicable due to its fast turn-around-time (two days). An IFN-y signature gene expression score (IFN-y score) was calculated using a NKI-developed algorithm. Association between IFN-y score and pathologic response or event-free survival (EFS) was examined by logistic regression and Cox analyses. The optimal cutoff between a high and low IFN-y score was defined based on a summary receiver operating characteristic (sROC) curve. Results: In total, 103 pts treated in the OpACIN-neo and PRADO studies had baseline tumor material available. Median age was 56 years, 62% was male, and 52% had a high baseline IFN-y score. The pRR of the total cohort was 70% (72/103 pts), including 56% (58/103) major pathologic response (MPR, 0-≤10% viable tumor) and 14% (14/103) partial responses (pPR, 10-≤50% viable tumor). 30% (31/103 pts) had no pathologic response. After a median follow-up of 25.2 months, 26 pts (25.2%) developed a melanoma relapse. The IFN-y score was significantly associated with response (OR 1.061, p < 0.001) and relapse (OR 0. 974, p = 0.029). The pRR was 89% (48/54) in pts with a high IFN-y score versus 49% (24/49) in those with a low IFN-y score (p < 0.001). Pts with a high IFN-y score were also less likely to develop a relapse (11% [6/54] versus 41% [20/49], p = 0.001). Conclusions: Pts with a high IFN-y score in pre-treatment biopsies are more likely to respond to neoadjuvant IPI + NIVO with favorable EFS. A rapid gene expression analysis enables the IFN-y score to be used in daily clinical practice to identify pts who might qualify for treatment escalation or de-escalation. The DONIMI study [NCT04133948] currently investigates different neoadjuvant treatment combinations in stage III melanoma pts based on their intratumoral IFN-y score.

Personalized response-directed surgery and adjuvant therapy after neoadjuvant ipilimumab and nivolumab in high-risk stage III melanoma: the PRADO trial

Neoadjuvant ipilimumab and nivolumab induces high pathologic response rates (pRRs) in clinical stage III nodal melanoma, and pathologic response is strongly associated with prolonged relapse-free survival (RFS). The PRADO extension cohort of the OpACIN-neo trial ( NCT02977052 ) addressed the feasibility and effect on clinical outcome of using pathologic response after neoadjuvant ipilimumab and nivolumab as a criterion for further treatment personalization. In total, 99 patients with clinical stage IIIb-d nodal melanoma were included and treated with 6 weeks of neoadjuvant ipilimumab 1 mg kg-1 and nivolumab 3 mg kg-1. In patients achieving major pathologic response (MPR, ≤10% viable tumor) in their index lymph node (ILN, the largest lymph node metastasis at baseline), therapeutic lymph node dissection (TLND) and adjuvant therapy were omitted. Patients with pathologic partial response (pPR; >10 to ≤50% viable tumor) underwent TLND only, whereas patients with pathologic non-response (pNR; >50% viable tumor) underwent TLND and adjuvant systemic therapy ± synchronous radiotherapy. Primary objectives were confirmation of pRR (ILN, at week 6) of the winner neoadjuvant combination scheme identified in OpACIN-neo; to investigate whether TLND can be safely omitted in patients achieving MPR; and to investigate whether RFS at 24 months can be improved for patients achieving pNR. ILN resection and ILN-response-tailored treatment were feasible. The pRR was 72%, including 61% MPR. Grade 3-4 toxicity within the first 12 weeks was observed in 22 (22%) patients. TLND was omitted in 59 of 60 patients with MPR, resulting in significantly lower surgical morbidity and better quality of life. The 24-month relapse-free survival and distant metastasis-free survival rates were 93% and 98% in patients with MPR, 64% and 64% in patients with pPR, and 71% and 76% in patients with pNR, respectively. These findings provide a strong rationale for randomized clinical trials testing response-directed treatment personalization after neoadjuvant ipilimumab and nivolumab.

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

9501

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.

IMPemBra, a phase 2 study comparing pembrolizumab with intermittent/short‐term dual MAPK pathway inhibition plus pembrolizumab in patients with melanoma harboring the BRAFV600 mutation: Three-year survival data and translational analyses

9552

Background: Continuous combination of MAPK pathway inhibition (MAPKi) and anti-PD-(L)1 showed high response rates, but also high frequency of treatment-related adverse events (TRAE) in BRAFV600-mutated melanoma patients (pts). Short‐time MAPKi already induces T cell infiltration in pts and was synergistic with anti-PD‐1 in a pre-clinical model. This phase 2b trial aimed to identify the optimal duration of MAPKi with dabrafenib + trametinib (D+T) in combination with pembrolizumab (PEM). We have previously shown that no SUSARs were observed, toxicity was related to duration of D+T, and response rates increased after addition of D+T. Here we present 3-year PFS and OS data and results of translational analyses. Methods: In IMPemBra, pts with treatment-naïve BRAFV600E/K mutant advanced melanoma started with PEM 200mg Q3W. After 2 cycles, pts were randomized to continue PEM only (cohort 1) or to receive in addition intermittent dabrafenib 150 mg BID + trametinib 2mg QD for 2 x 1 week (cohort 2), 2 x 2 weeks (cohort 3) or continuous for 6 weeks (cohort 4). All cohorts continued PEM for up to 2 years. Primary endpoints were safety, treatment adherence and immune-activating capacity of the different regimens. Secondary endpoints were objective response rate (ORR) and PFS, OS was an exploratory endpoint. For survival analyses, pts that received D+T (cohort 2-4) were pooled. Results: Thirty-two pts were randomized, 56% were male, 53% had M1c disease and 88% had a LDH level < ULN. No new grade 3-4 TRAE were observed; frequencies were 12%, 12%, 50% and 62% for pts in cohort 1, 2, 3 and 4, respectively. ORRs were 75% in cohort 1 and 2, and 88% in cohort 3 and 4. The frequency of PD1+CD8+ T cells in peripheral blood decreased slightly during treatment and there were no differences between cohorts. In cohort 1 and 2, an increase in IFNγ signature in tumor biopsies was already observed after 6 weeks of PEM, in cohort 3-4 an increase in IFNγ signature was observed in week 9, after addition of D+T. The same pattern was observed for CD8+ T cell infiltration and PD-L1 expression. After a median follow-up of 43.5 months, the median PFS of pts treated with PEM monotherapy was 10.6 months versus 32.3 months for pts treated with PEM plus D+T (p = 0.19). The 3-year PFS rates were 25.0% and 50.0% respectively. Median OS was 40.5 months in the PEM pts and not reached for pts treated with PEM plus D+T (p = 0.32); 3-year OS rates were 62.5% and 70.8% respectively. Conclusions: IMPemBra demonstrated that short-term addition of intermittent D+T to PEM seems a more feasible, tolerable and an effective alternative for the continuous triple combination. In addition, it gives the opportunity to treat with second line targeted therapy after disease progression. Therefore, this regimen should be considered for further investigation in a larger cohort. Clinical trial information: NCT02625337.

Survival update of neoadjuvant ipilimumab + nivolumab in macroscopic stage III melanoma: The OpACIN and OpACIN-neo trials

9572

Background: OpACIN was the first trial testing neoadjuvant ipilimumab (IPI) + nivolumab (NIVO) versus the same combination given adjuvant. An unexpected high pathologic responses of 78% was observed in the neoadjuvant arm with a 2-year relapse-free survival (RFS) rate of 80%. The subsequent OpACIN-neo trial tested 3 different dosing schedules of neoadjuvant IPI + NIVO and identified 2 cycles IPI 1 mg/kg + NIVO 3 mg/kg q3w as most favorable schedule with a pathologic response rate of 77% and 20% grade 3-4 immune-related adverse events. Long-term data on the durability of the pathologic (path) responses upon neoadjuvant checkpoint inhibition are lacking so far. Therefore, we present here the updated RFS and overall survival (OS) data of both trials. Methods: In OpACIN 20 macroscopic stage III melanoma pts were randomized to receive either IPI 3 mg/kg + NIVO 1 mg/kg q3w 4 cycles adjuvant after lymph node dissection or split 2 cycles neoadjuvant and 2 adjuvant. In OpACIN-neo 86 macroscopic stage III melanoma pts were randomized to arm A (2x IPI 3 mg/kg + NIVO 1 mg/kg q3w, n=30), arm B (2x IPI 1 mg/kg + NIVO 3 mg/kg q3w, n=30), or arm C (2x IPI 3 mg/kg q3w followed by 2x NIVO 3 mg/kg q2w, n=26) followed by lymph node dissection in week 6. RFS and OS were estimated using Kaplan Meier method. All comparative efficacy endpoints are descriptive for OpACIN, since the trial was not powered for comparison of the arms. Results: After a median follow-up (FU) of 68.6 months for OpACIN (minimum FU of 59.8 months), median RFS and OS were not reached. Only 1/7 patients (pts) with a pathologic response on neoadjuvant therapy has relapsed. Estimated 5-year RFS and OS rates for the neoadjuvant arm were 70.0% (95%CI: 46.7-100.0) and 90.0% (95%CI: 73.2-100.0) versus 60.0% (95%CI 36.2-99.5) and 70.0% (95%CI: 46.7-100.0) for the adjuvant arm. After a median FU of 46.8 months for OpACIN-neo (minimum FU of 38.2 months), median RFS and OS were not reached. Of pts with path response on neoadjuvant therapy, 3/64 (4.7%) had an event (2 pts relapsed, 1 pt died due to toxicity), versus 14/21 (66.7%) without path response. This resulted in a 3-year RFS rate of 95.3% (95%CI: 90.3-100.0) for responding versus 36.8% (95%CI: 20.4-66.4) for non-responding pts (p<0.001). Of the pts who relapsed after response, 1 had major path response (<10% vital tumor) and 1 a partial response (10-15% vital tumor). Estimated 3-year RFS and OS rates are presented in the Table. Conclusions: Updated data from OpACIN and OpaCIN-neo trials confirm the durability of responses upon neoadjuvant combination checkpoint inhibition in high risk stage III melanoma. Pathologic response remains a reliable surrogate marker for RFS and OS. Clinical trial information: NCT02437279, NCT02977052. [Table: see text]

Representativeness of the Index Lymph Node for Total Nodal Basin in Pathologic Response Assessment After Neoadjuvant Checkpoint Inhibitor Therapy in Patients With Stage III Melanoma

IMPORTANCE

Neoadjuvant checkpoint inhibition in patients with high-risk stage III melanoma shows high pathologic response rates associated with a durable relapse-free survival. Whether a therapeutic lymph node dissection (TLND) can be safely omitted when a major pathologic response in the largest lymph node metastasis at baseline (index lymph node; ILN) is obtained is currently being investigated. A previous small pilot study (n = 12) showed that the response in the ILN may be representative of the pathologic response in the entire TLND specimen.

OBJECTIVE

To assess the concordance of response between the ILN and the total lymph node bed in a larger clinical trial population.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective pathologic response analysis of a multicenter clinical trial population of patients from the randomized Study to Identify the Optimal Adjuvant Combination Scheme of Ipilimumab and Nivolumab in Melanoma Patients (OpACIN) and Optimal Neo-Adjuvant Combination Scheme of Ipilimumab and Nivolumab (OpACIN-neo) trials. Included patients were treated with 6 weeks neoadjuvant ipilimumab plus nivolumab. Patient inclusion into the trials was conducted from August 12, 2015, to October 24, 2016 (OpACIN), and November 24, 2016, and June 28, 2018 (OpACIN-neo). Data were analyzed from April 1, 2020, to August 31, 2021.

MAIN OUTCOMES AND MEASURES

Concordance of the pathologic response between the ILN and the TLND tumor bed. The pathologic response of the ILN was retrospectively assessed according to the International Neoadjuvant Melanoma Consortium criteria and compared with the pathologic response of the entire TLND specimen.

RESULTS

A total of 82 patients treated with neoadjuvant ipilimumab and nivolumab followed by TLND (48 [59%] were male; median age, 58.5 [range, 18-80] years) were included. The pathologic response in the ILN was concordant with the entire TLND specimen response in 81 of 82 patients (99%) and in 79 of 82 patients (96%) concordant when comparing the ILN response with the response in every individual lymph node. In the single patient with a discordant response, the ILN response (20% viable tumor, partial pathologic response) underestimated the entire TLND specimen response (5% viable, near-complete pathologic response). Two other patients each had 1 small nonindex node that contained 80% viable tumor (pathologic nonresponse) whereas all other lymph nodes (including the ILN) showed a partial pathologic response. In these 2 patients, the risk of regional relapse might potentially have been increased if TLND had been omitted.

CONCLUSIONS AND RELEVANCE

The results of this study suggest that the pathologic response of the ILN may be considered a reliable indicator of the entire TLND specimen response and may support the ILN response-directed omission of TLND in a prospective trial.

Technologic (R)Evolution Leads to Detection of More Sentinel Nodes in Patients with Melanoma in the Head and Neck Region

Sentinel lymph node (SN) biopsy (SNB) has proven to be a valuable tool for staging melanoma patients. Since its introduction in the early 1990s, this procedure has undergone several technologic refinements, including the introduction of SPECT/CT, as well as radioguidance and fluorescence guidance. The purpose of the current study was to evaluate the effect of this technologic evolution on SNB in the head and neck region. The primary endpoint was the false-negative (FN) rate. Secondary endpoints were number of harvested SNs, overall operation time, operation time per harvested SN, and postoperative complications. Methods: A retrospective database was queried for cutaneous head and neck melanoma patients who underwent SNB at The Netherlands Cancer Institute between 1993 and 2016. The implementation of new detection techniques was divided into 4 groups: 1993-2005, with preoperative lymphoscintigraphy and intraoperative use of both a γ-ray detection probe and patent blue (n = 30); 2006-2007, with addition of preoperative road maps based on SPECT/CT (n = 15); 2008-2009, with intraoperative use of a portable γ-camera (n = 40); and 2010-2016, with addition of near-infrared fluorescence guidance (n = 192). Results: In total, 277 patients were included. At least 1 SN was identified in all patients. A tumor-positive SN was found in 59 patients (21.3%): 10 in group 1 (33.3%), 3 in group 2 (20.0%), 6 in group 3 (15.0%), and 40 in group 4 (20.8%). Regional recurrences in patients with tumor-negative SNs resulted in an overall FN rate of 11.9% (group 1, 16.7%; group 2, 0%; group 3, 14.3%; group 4, 11.1%). The number of harvested nodes increased with advancing technologies (P = 0.003), whereas Breslow thickness and operation time per harvested SN decreased (P = 0.003 and P = 0.017, respectively). There was no significant difference in percentage of tumor-positive SNs, overall operation time, and complication rate between the different groups. Conclusion: The use of advanced detection technologies led to a higher number of identified SNs without an increase in overall operation time, possibly indicating an improved surgical efficiency. Operation time per harvested SN decreased; the average FN rate remained 11.9% and was unchanged over 23 y. There was no significant change in postoperative complication rate.

Neoadjuvant ipilimumab plus nivolumab in synchronous clinical stage III melanoma

BACKGROUND

Patients with synchronous clinical stage III melanoma can present with primary melanoma lesions, locally recurrent melanoma or in-transit metastases. Neoadjuvant ipilimumab plus nivolumab induces high pathologic response rates and an impressive relapse-free survival in patients with nodal macroscopic stage III melanoma. Whether primary site melanoma and in-transit metastases respond similarly to lymph node metastases with neoadjuvant immunotherapy is largely unknown. Such data would clarify whether surgical excision of these melanoma lesions should be performed before neoadjuvant therapy or whether it could be deferred and performed in conjunction with lymphadenectomy following neoadjuvant immunotherapy.

PATIENTS

Patients with synchronous clinical stage III melanoma were identified from the OpACIN, OpACIN-neo and PRADO neoadjuvant trials, where all patients were treated with ipilimumab plus nivolumab. An additional case treated outside those clinical trials was included.

RESULTS

Seven patients were identified; six patients had a concordant response in primary site melanoma lesions or in-transit metastasis and the lymph node metastases. One patient had concordant progression in both the primary and nodal tumour lesions and developed stage IV disease during neoadjuvant treatment, and thus, no resection was performed.

CONCLUSION

Pathologic response following neoadjuvant ipilimumab plus nivolumab in primary site melanoma lesions or in-transit metastasis is concordant with a response in the lymph node metastases, indicating that there may be no need to perform upfront surgery to these melanoma lesions prior to neoadjuvant treatment.

Pathological response and survival with neoadjuvant therapy in melanoma: a pooled analysis from the International Neoadjuvant Melanoma Consortium (INMC)

The association among pathological response, recurrence-free survival (RFS) and overall survival (OS) with neoadjuvant therapy in melanoma remains unclear. In this study, we pooled data from six clinical trials of anti-PD-1-based immunotherapy or BRAF/MEK targeted therapy. In total, 192 patients were included; 141 received immunotherapy (104, combination of ipilimumab and nivolumab; 37, anti-PD-1 monotherapy), and 51 received targeted therapy. A pathological complete response (pCR) occurred in 40% of patients: 47% with targeted therapy and 33% with immunotherapy (43% combination and 20% monotherapy). pCR correlated with improved RFS (pCR 2-year 89% versus no pCR 50%, P < 0.001) and OS (pCR 2-year OS 95% versus no pCR 83%, P = 0.027). In patients with pCR, near pCR or partial pathological response with immunotherapy, very few relapses were seen (2-year RFS 96%), and, at this writing, no patient has died from melanoma, whereas, even with pCR from targeted therapy, the 2-year RFS was only 79%, and OS was only 91%. Pathological response should be an early surrogate endpoint for clinical trials and a new benchmark for development and approval in melanoma.

Challenges in sentinel node pathology in the era of adjuvant treatment

BACKGROUND

With the approval of adjuvant therapy for stage III melanoma, accurate staging is more important than ever. Sentinel node biopsy (SNB) is an accurate staging tool, yet the presence of capsular nevi (CN) can lead to a false-positive diagnosis.

PATIENTS AND METHODS

Retrospective analysis of the American Joint Committee on Cancer 7th edition stage IIIA melanoma patients who were treated at our institute between 2000 and 2015. SNB slides were reviewed for this study by an expert melanoma pathologist.

RESULTS

Of 159 eligible patients, 14 originally diagnosed with metastatic melanoma merely had CN (8.8%). Another two merely had melanophages (1.3%). Thus, 10.1% of SNs were considered false positive after revision. In 12 patients, the SN tumor burden was originally reported as larger than 1 mm but turned out to be less than 1 mm. Four patients originally reported as SN tumor burden less than 1 mm before revision turned out to have larger than 1 mm. These patients might have been over- or undertreated in the current era of adjuvant therapy for stage III melanoma.

CONCLUSIONS

Distinguishing metastatic melanoma from benign CN and melanophages can be a diagnostic challenge. We plead for an expert pathologists' review, especially when using the SNB + results to determine treatment consequences.

Abstract 3271: 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

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 &lt;60 compared to pts &gt;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.

Abstract 3412: 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

Introduction The outcome of high-risk stage III melanoma patients was poor with a 5-year overall survival (OS) rate of &lt;50%. Adjuvant ipilimumab (IPI) improved the relapse-free survival (RFS) and OS, and adjuvant anti-PD-1 improved the RFS further. Preclinical data suggested that neoadjuvant therapy may be more effective than adjuvant therapy due to broader immune activation. The OpACIN trial compared neoadjuvant IPI plus nivolumab (NIVO) versus adjuvant IPI plus NIVO, while the subsequent OpACIN-neo trial tested three different dosing schedules of neoadjuvant IPI plus NIVO only. Neoadjuvant IPI plus NIVO induced high pathologic response rates of 74-78%. Here, we present the 36- and 18-months RFS update of the OpACIN and OpACIN-neo trial, respectively.

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 &lt;50% viable tumor cells and centrally reviewed by a blinded pathologist. RFS rates were estimated using the Kaplan-Meier method.

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.

SOX10 is as specific as S100 protein in detecting metastases of melanoma in lymph nodes and is recommended for sentinel lymph node assessment

BACKGROUND

Sentinel lymph node (SLN) biopsy remains crucial for melanoma staging. The European Organisation for Research and Treatment of Cancer Melanoma Group recommends performing immunohistochemical stainings for reproducible identification of melanoma metastases. S100 protein (pS100) is a commonly used melanocytic antigen because of its high sensitivity in spite of relatively low specificity. SRY-related HMG-box 10 protein (SOX10) is a transcription factor characterising neural crest-derived cells. It is uniformly expressed mostly in the nuclei of melanocytes, neural, and myoepithelial cells. Pathologists sometimes prefer SOX10 as a melanoma marker, but it has not yet been investigated on a large-scale to confirm that it is reliable and recommendable for routine SLN evaluation.

METHODS

Four hundred one treatment-naïve lymph node (LN) metastatic melanomas were included in high-density tissue microarrays and were assessed for the presence of SOX10 and pS100 by immunohistochemistry. The slides were digitalised, shared and evaluated by a panel of experienced melanoma pathologists.

RESULTS

The vast majority of melanomas were double-positive for pS100 and SOX10 (93.2%); a small percentage of the cases (3.9%) were double-negative melanomas. Discordance between the two markers was observed: 1.9% pS100(-)/SOX10(+) and 0.75% pS100(+)/SOX10(-). SOX10 was not expressed by immune cell types in the LN, resulting in a less controversial interpretation of the staining.

CONCLUSIONS

SOX10 is as equally specific as pS100 for the detection of melanoma metastases in LNs. The interpretation of SOX10 staining is highly reproducible among different centres and different pathologists because of the absence of staining of immune cells.

Identification of the optimal combination dosing schedule of neoadjuvant ipilimumab plus nivolumab in macroscopic stage III melanoma (OpACIN-neo): a multicentre, phase 2, randomised, controlled trial

BACKGROUND

The outcome of patients with macroscopic stage III melanoma is poor. Neoadjuvant treatment with ipilimumab plus nivolumab at the standard dosing schedule induced pathological responses in a high proportion of patients in two small independent early-phase trials, and no patients with a pathological response have relapsed after a median follow up of 32 months. However, toxicity of the standard ipilimumab plus nivolumab dosing schedule was high, preventing its broader clinical use. The aim of the OpACIN-neo trial was to identify a dosing schedule of ipilimumab plus nivolumab that is less toxic but equally effective.

METHODS

OpACIN-neo is a multicentre, open-label, phase 2, randomised, controlled trial. Eligible patients were aged at least 18 years, had a WHO performance status of 0-1, had resectable stage III melanoma involving lymph nodes only, and measurable disease according to the Response Evaluation Criteria in Solid Tumors version 1.1. Patients were enrolled from three medical centres in Australia, Sweden, and the Netherlands, and were randomly assigned (1:1:1), stratified by site, to one of three neoadjuvant dosing schedules: group A, two cycles of ipilimumab 3 mg/kg plus nivolumab 1 mg/kg once every 3 weeks intravenously; group B, two cycles of ipilimumab 1 mg/kg plus nivolumab 3 mg/kg once every 3 weeks intravenously; or group C, two cycles of ipilimumab 3 mg/kg once every 3 weeks directly followed by two cycles of nivolumab 3 mg/kg once every 2 weeks intravenously. The investigators, site staff, and patients were aware of the treatment assignment during the study participation. Pathologists were masked to treatment allocation and all other data. The primary endpoints were the proportion of patients with grade 3-4 immune-related toxicity within the first 12 weeks and the proportion of patients achieving a radiological objective response and pathological response at 6 weeks. Analyses were done in all patients who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, number NCT02977052, and is ongoing with an additional extension cohort and to complete survival analysis.

FINDINGS

Between Nov 24, 2016 and June 28, 2018, 105 patients were screened for eligibility, of whom 89 (85%) eligible patients were enrolled and randomly assigned to one of the three groups. Three patients were excluded after randomisation because they were found to be ineligible, and 86 received at least one dose of study drug; 30 patients in group A, 30 in group B, and 26 in group C (accrual to this group was closed early upon advice of the Data Safety Monitoring Board on June 4, 2018 because of severe adverse events). Within the first 12 weeks, grade 3-4 immune-related adverse events were observed in 12 (40%) of 30 patients in group A, six (20%) of 30 in group B, and 13 (50%) of 26 in group C. The difference in grade 3-4 toxicity between group B and A was -20% (95% CI -46 to 6; p=0·158) and between group C and group A was 10% (-20 to 40; p=0·591). The most common grade 3-4 adverse events were elevated liver enzymes in group A (six [20%)]) and colitis in group C (five [19%]); in group B, none of the grade 3-4 adverse events were seen in more than one patient. One patient (in group A) died 9·5 months after the start of treatment due to the consequences of late-onset immune-related encephalitis, which was possibly treatment-related. 19 (63% [95% CI 44-80]) of 30 patients in group A, 17 (57% [37-75]) of 30 in group B, and nine (35% [17-56]) of 26 in group C achieved a radiological objective response, while pathological responses occurred in 24 (80% [61-92]) patients in group A, 23 (77% [58-90]) in group B, and 17 (65% [44-83]) in group C.

INTERPRETATION

OpACIN-neo identified a tolerable neoadjuvant dosing schedule (group B: two cycles of ipilimumab 1 mg/kg plus nivolumab 3 mg/kg) that induces a pathological response in a high proportion of patients and might be suitable for broader clinical use. When more mature data confirm these early observations, this schedule should be tested in randomised phase 3 studies versus adjuvant therapies, which are the current standard-of-care systemic therapy for patients with stage III melanoma.

FUNDING

Bristol-Myers Squibb.

Inter-observer variation in the histopathology reports of head and neck melanoma; a comparison between the seventh and eighth edition of the AJCC staging system

BACKGROUND

TNM staging of melanoma has recently been altered by the introduction of the 8th edition of the AJCC Cancer Staging manual. The purpose of this study is to analyze the inter-observer variation of histopathology reports and its effect on recommended treatment policy.

METHODS

We retrospectively analyzed 296 cases, diagnosed as primary cutaneous head and neck melanoma (2005-2016), referred to the Netherlands Cancer Institute (NCI) for treatment after prior diagnosis in another hospital (non-NCI). All reports were analyzed for patients demographics, tumor characteristics and histopathologic features.

RESULTS

In 53% and 40% of the cases, the histopathologic parameters were discordant, according to AJCC 7th and 8th edition, respectively. This indicated a perfect inter-observer agreement for the measurement of Breslow thickness (Intraclass correlation coefficient (ICC) = 0.981) and a substantial agreement for subtype (kappa statistic (κ) = 0.648) and ulceration (κ = 0.802), while only moderate for dermal mitotic activity (κ = 0.472). After NCI review, recommended treatment policies were changed in 13% and 11% of the patients when applying TNM 7 and TNM 8, respectively. Scheduling sentinel lymph node biopsy (SLNB) changed in 14 (5%) and 10 (3%) cases when using TNM 7 and TNM 8, respectively.

CONCLUSION

Review by a NCI pathologist of histopathologic parameters of primary cutaneous head and neck melanoma led to significant changes in treatment decision. Introduction of the AJCC 8th edition led to slightly less discordances between NCI and non-NCI reports and consequently smaller impact on treatment planning. Expert review remains indicated when a SLNB is considered for additional staging in selected cases.

Vemurafenib plus cobimetinib in unresectable stage IIIc or stage IV melanoma: response monitoring and resistance prediction with positron emission tomography and tumor characteristics (REPOSIT): study protocol of a phase II, open-label, multicenter study

BACKGROUND

In patients with BRAFV600 mutated unresectable stage IIIc or metastatic melanoma, molecular targeted therapy with combined BRAF/MEK-inhibitor vemurafenib plus cobimetinib has shown a significantly improved progression-free survival and overall survival compared to treatment with vemurafenib alone. Nevertheless, the majority of BRAFV600 mutation-positive melanoma patients will eventually develop resistance to treatment. Molecular imaging with 18F-Fluorodeoxyglucose (18F-FDG) PET has been used to monitor response to vemurafenib in some BRAFV600 mutated metastatic melanoma patients, showing a rapid decline of 18F-FDG uptake within 2 weeks following treatment. Furthermore, preliminary results suggest that metabolic alterations might predict the development of resistance to treatment. 18F-Fluoro-3'-deoxy-3'L-fluorothymidine (18F-FLT), a PET-tracer visualizing proliferation, might be more suitable to predict response or resistance to therapy than 18F-FDG.

METHODS

This phase II, open-label, multicenter study evaluates whether metabolic response to treatment with vemurafenib plus cobimetinib in the first 7 weeks as assessed by 18F-FDG/18F-FLT PET can predict progression-free survival and whether early changes in 18F-FDG/18F-FLT can be used for early detection of treatment response compared to standard response assessment with RECISTv1.1 ceCT at 7 weeks. Ninety patients with BRAFV600E/K mutated unresectable stage IIIc/IV melanoma will be included. Prior to and during treatment all patients will undergo 18F-FDG PET/CT and in 25 patients additional 18F-FLT PET/CT is performed. Histopathological tumor characterization is assessed in a subset of 40 patients to unravel mechanisms of resistance. Furthermore, in all patients, blood samples are taken for pharmacokinetic analysis of vemurafenib/cobimetinib. Outcomes are correlated with PET/CT-imaging and therapy response.

DISCUSSION

The results of this study will help in linking PET measured metabolic alterations induced by targeted therapy of BRAFV600 mutated melanoma to molecular changes within the tumor. We will be able to correlate both 18F-FDG and 18F-FLT PET to outcome and decide on the best modality to predict long-term remissions to combined BRAF/MEK-inhibitors. Results coming from this study may help in identifying responders from non-responders early after the initiation of therapy and reveal early development of resistance to vemurafenib/cobimetinib. Furthermore, we believe that the results can be fundamental for further optimizing individual patient treatment.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02414750. Registered 10 April 2015, retrospectively registered.

[Castleman's disease, a fatal cause of lymph node enlargement and fever]

A 71-year old Turkish man with fever, night sweats and generalized lymphadenopathy was diagnosed as having multicentric Castleman's disease. This is a rare and often fatal cause of lymph node enlargement and fever. Histological investigation confirms the diagnosis, but the morphological features closely resemble reactive lymphadenopathy or lymphoma. Infection with human herpes virus 8 is associated with Castleman's disease, in both hiv-positive and hiv-negative patients. An interleukin-6 mediated immune response against HHV-8 seems to play an important role in the pathogenesis of the multicentric form of Castleman's disease. The disease is usually rapidly progressive, but can have a milder course. There is no standard treatment: usually systemic chemotherapy in combination with steroids is applied..Recently, promising results have been obtained using rituximab and anti-IL-6-receptor antibodies.