Single-agent anti-PD-1 or combined with ipilimumab in patients with mucosal melanoma: an international, retrospective, cohort study

BACKGROUND

Mucosal melanoma (MM) is a rare melanoma subtype with distinct biology and poor prognosis. Data on the efficacy of immune checkpoint inhibitors (ICIs) is limited. We determined the efficacy of ICIs in MM, analysed by primary site and ethnicity/race.

PATIENTS AND METHODS

Retrospective cohort study from 25 cancer centres in Australia, Europe, USA and Asia. Patients with histologically confirmed MM were treated with anti-PD1+/-ipilimumab. Primary endpoints were response rate (RR), progression-free survival (PFS), overall survival (OS) by primary site (naso-oral, urogenital, anorectal, other), ethnicity/race (Caucasian, Asian, Other) and treatment. Univariate and multivariate Cox proportional hazard model analyses were conducted.

RESULTS

In total, 545 patients were included: 331 (63%) Caucasian, 176 (33%) Asian and 20 (4%) Other. Primary sites included 113 (21%) anorectal, 178 (32%) urogenital, 206 (38%) naso-oral and 45 (8%) other. 348 (64%) received anti-PD1 and 197 (36%) anti-PD1/ipilimumab. RR, PFS and OS did not differ by primary site, ethnicity/race or treatment. RR for naso-oral was numerically higher for anti-PD1/ipilimumab (40%, 95% CI 29-54%) compared with anti-PD1 (29%, 95% CI 21-37%). 35% of patients that initially responded progressed. Median duration of response (mDOR) was 26 months (95% CI 18-NR [Not Reached]). Factors associated with short PFS were ECOG PS ≥3 (p<0.01), LDH >ULN (p=0.01), lung metastases (p<0.01) and ≥1 previous treatments (p<0.01). Factors associated with short OS were ECOG PS ≥1 (p<0.01), LDH >ULN (p=0.03), lung metastases (p<0.01) and ≥1 previous treatments (p<0.01).

CONCLUSIONS

MM has poor prognosis. Treatment efficacy of anti-PD1+/-ipilimumab was similar and did not differ by ethnicity/race. Naso-oral primaries had numerically higher response to anti-PD1/ipilimumab, without difference in survival. The addition of ipilimumab did not show greater benefit over anti-PD1 for other primary sites. In responders, mDOR was short and acquired resistance was common. Other factors, including site and number of metastases were associated with survival.

Acral lentiginous melanoma histotype predicts outcome in clinical stage I-II melanoma patients: an International multicenter study

BACKGROUND

In the American Joint Committee on Cancer (AJCC) classification, acral lentiginous melanoma (ALM) histotype ALM is not included as an independent prognostic factor; in small series its negative prognostic impact on disease-free survival (DFS) and overall survival (OS) has been linked to the greater Breslow thickness (BT).

PATIENTS AND METHODS

The study was carried out at four referral melanoma centers (three Italian and one Polish). Clinical consecutive patients with stage I-II melanoma, who were diagnosed, treated, and followed up between January 1998 and March 2018 in annotated specific databases were included.

RESULTS

Overall, 6734 were evaluable, 4349 with superficial spreading melanoma (SSM), 2132 with nodular melanoma (NM), and 253 with ALM. At univariable analysis, a statistically significant worse DFS [hazard ratio (HR) 2.72, 95% confidence interval (CI) 2.24-3.30; P < 0.001] and OS (HR 2.67, 95% CI 2.15-3.32; P < 0.001) were found in patients with ALM compared with SSM. Similarly, the NM histotype was associated with a worse prognosis compared with the SSM histotype (DFS: HR 2.29, 95% CI 2.08-2.52; P < 0.001 and OS: HR 2.21, 95% CI 1.99-2.46; P < 0.001). At multivariable analysis, after adjusting for age, sex, BT, ulceration, and the sentinel lymph node status, a statistically significant worse DFS [adjusted HR (aHR; ALM versus SSM) 1.25, 95% CI 1.02-1.52; P = 0.028] was confirmed for patients with ALM. For patients with NM, instead, no impact of histology was found in terms of DFS [aHR (NM versus SSM) 1.04, 95% CI 0.93-1.15; P = 0.513] and OS [aHR (NM versus SSM) 0.96, 95% CI 0.86-1.08; P = 0.548].

CONCLUSIONS

ALM is associated with a worse long-term DFS. Our results could have important clinical implications for patients' stratification in future clinical trials and the incorporation of ALM histotype in the new AJCC classification as an independent prognostic factor.