Phase I study of the anti-endothelin B receptor antibody-drug conjugate DEDN6526A in patients with metastatic or unresectable cutaneous, mucosal, or uveal melanoma.

Background Endothelin B receptor (ETBR) is involved in melanoma pathogenesis and is overexpressed in metastatic melanoma. The antibody-drug conjugate DEDN6526A targets ETBR and is comprised of the humanized anti-ETBR monoclonal antibody conjugated to the anti-mitotic agent monomethyl auristatin E (MMAE). Methods This Phase I study evaluated the safety, pharmacokinetics, pharmacodynamics, and anti-tumor activity of DEDN6526A (0.3-2.8 mg/kg) given every 3 weeks (q3w) in patients with metastatic or unresectable cutaneous, mucosal, or uveal melanoma. Results Fifty-three patients received a median of 6 doses of DEDN6526A (range 1-49). The most common drug-related adverse events (>25% across dose levels) were fatigue, peripheral neuropathy, nausea, diarrhea, alopecia, and chills. Three patients in dose-escalation experienced a dose-limiting toxicity (infusion-related reaction, increased ALT/AST, and drug-induced liver injury). Based on cumulative safety data across all dose levels, the recommended Phase II dose (RP2D) for DEDN6526A was 2.4 mg/kg intravenous (IV) q3w. The pharmacokinetics of antibody-conjugated MMAE and total antibody were dose-proportional at doses ranging from 1.8-2.8 mg/kg. A trend toward faster clearance was observed at doses of 0.3-1.2 mg/kg. There were 6 partial responses (11%) in patients with metastatic cutaneous or mucosal melanoma, and 17 patients (32%) had prolonged stable disease ≥6 months. Responses were independent of BRAF mutation status but did correlate with ETBR expression. Conclusion DEDN6526A administered at the RP2D of 2.4 mg/kg q3w had an acceptable safety profile and showed evidence of anti-tumor activity in patients with cutaneous, mucosal, and uveal melanoma. ClinicalTrials.gov identifier: NCT01522664.

Elevated levels of tumour apolipoprotein D independently predict poor outcome in breast cancer patients.

AIMS: Apolipoprotein D (ApoD) is a protein that is regulated by androgen and oestrogen, and is a major constituent of breast cysts. Although ApoD has been reported to be a marker of breast cancer, its prognostic importance in invasive breast cancer is unclear. The aim of this study was to investigate the relationship between ApoD protein expression, oestrogen receptor-α (ERα) expression and androgen receptor (AR) expression in predicting breast cancer outcome. METHODS AND RESULTS: ApoD levels were measured by the use of immunohistochemistry and video image analysis on tissue sections from a breast cancer cohort (n = 214). We assessed the associations of ApoD expression with disease-free survival (DFS), metastasis-free survival (MFS), and overall survival (OS). We also assessed the relationship between ApoD expression, AR expression and ERα expression in predicting OS. ApoD expression (>1% ApoD positivity) was found in 72% (154/214) of tissues. High ApoD positivity (≥20.7%, fourth quartile) was an independent predictor of MFS and OS, and conferred a 2.2-fold increased risk of developing metastatic disease and a 2.1-fold increased risk of breast cancer-related death. ApoD positivity was not associated with AR or ERα nuclear positivity. However, patients with (≥1%) ERα-positive cancers with low (<20.7%) ApoD positivity, or those showing high (≥78%) AR positivity and low (<20.7%) ApoD positivity had better OS than other patient groups. CONCLUSIONS: ApoD expression could be used to predict breast cancer prognosis independently of ERα and AR expression.

Pembrolizumab versus ipilimumab in advanced melanoma (KEYNOTE-006): post-hoc 5-year results from an open-label, multicentre, randomised, controlled, phase 3 study.

BACKGROUND: Pembrolizumab improved progression-free survival and overall survival versus ipilimumab in patients with advanced melanoma and is now a standard of care in the first-line setting. However, the optimal duration of anti-PD-1 administration is unknown. We present results from 5 years of follow-up of patients in KEYNOTE-006. METHODS: KEYNOTE-006 was an open-label, multicentre, randomised, controlled, phase 3 study done at 87 academic institutions, hospitals, and cancer centres in 16 countries. Patients aged at least 18 years with Eastern Cooperative Oncology Group performance status of 0 or 1, ipilimumab-naive histologically confirmed advanced melanoma with known BRAFV600 status and up to one previous systemic therapy were randomly assigned (1:1:1) to intravenous pembrolizumab 10 mg/kg every 2 weeks or every 3 weeks or four doses of intravenous ipilimumab 3 mg/kg every 3 weeks. Treatments were assigned using a centralised, computer-generated allocation schedule with blocked randomisation within strata. Exploratory combination of data from the two pembrolizumab dosing regimen groups was not protocol-specified. Pembrolizumab treatment continued for up to 24 months. Eligible patients who discontinued pembrolizumab with stable disease or better after receiving at least 24 months of pembrolizumab or discontinued with complete response after at least 6 months of pembrolizumab and then progressed could receive an additional 17 cycles of pembrolizumab. Co-primary endpoints were overall survival and progression-free survival. Efficacy was analysed in all randomly assigned patients, and safety was analysed in all randomly assigned patients who received at least one dose of study treatment. Exploratory assessment of efficacy and safety at 5 years' follow-up was not specified in the protocol. Data cutoff for this analysis was Dec 3, 2018. Recruitment is closed; the study is ongoing. This study is registered with ClinicalTrials.gov, number NCT01866319. FINDINGS: Between Sept 18, 2013, and March 3, 2014, 834 patients were enrolled and randomly assigned to receive pembrolizumab (every 2 weeks, n=279; every 3 weeks, n=277), or ipilimumab (n=278). After a median follow-up of 57·7 months (IQR 56·7-59·2) in surviving patients, median overall survival was 32·7 months (95% CI 24·5-41·6) in the combined pembrolizumab groups and 15·9 months (13·3-22·0) in the ipilimumab group (hazard ratio [HR] 0·73, 95% CI 0·61-0·88, p=0·00049). Median progression-free survival was 8·4 months (95% CI 6·6-11·3) in the combined pembrolizumab groups versus 3·4 months (2·9-4·2) in the ipilimumab group (HR 0·57, 95% CI 0·48-0·67, p<0·0001). Grade 3-4 treatment-related adverse events occurred in 96 (17%) of 555 patients in the combined pembrolizumab groups and in 50 (20%) of 256 patients in the ipilimumab group; the most common of these events were colitis (11 [2%] vs 16 [6%]), diarrhoea (ten [2%] vs seven [3%]), and fatigue (four [<1%] vs three [1%]). Any-grade serious treatment-related adverse events occurred in 75 (14%) patients in the combined pembrolizumab groups and in 45 (18%) patients in the ipilimumab group. One patient assigned to pembrolizumab died from treatment-related sepsis. INTERPRETATION: Pembrolizumab continued to show superiority over ipilimumab after almost 5 years of follow-up. These results provide further support for use of pembrolizumab in patients with advanced melanoma. FUNDING: Merck Sharp & Dohme.

Standard-dose pembrolizumab in combination with reduced-dose ipilimumab for patients with advanced melanoma (KEYNOTE-029): an open-label, phase 1b trial.

BACKGROUND: Reduced-dose nivolumab in combination with standard-dose ipilimumab improves objective response and progression-free survival compared with standard-dose ipilimumab alone, but increases toxicity. We assessed the safety and anti-tumour activity of standard-dose pembrolizumab in combination with reduced-dose ipilimumab. METHODS: In this open-label, phase 1b trial, we recruited patients from 12 medical centres in Australia, New Zealand, and the USA. Eligible patients were aged at least 18 years, had advanced melanoma, had an Eastern Coooperative Oncology Group performance status of 0 or 1, had measurable disease according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, had adequate organ function, had resolution of toxic effects of the most recent previous chemotherapy to grade 1 or less, had no active autoimmune disease requiring systemic steroids or immunosuppressive agents, had no active non-infectious pneumonitis, had no uncontrolled thyroid dysfunction or diabetes, had no active brain metastases, and had not received previous immune checkpoint inhibitor therapy. Patients received intravenous pembrolizumab 2 mg/kg plus intravenous ipilimumab 1 mg/kg every 3 weeks for four doses, followed by intravenous pembrolizumab 2 mg/kg every 3 weeks for up to 2 years or disease progression, intolerable toxicity, withdrawal of consent, or investigator decision. The primary endpoint was safety and tolerability. The proportion of patients achieving an objective response assessed per RECIST version 1.1 by independent central review and overall survival were secondary endpoints. We also assessed progression-free survival. The primary endpoint was assessed in all patients who received at least one dose of combination therapy. Activity was assessed in all enrolled patients. This trial is registered with ClinicalTrials.gov, number NCT02089685. Enrolment into this cohort is closed, but patients are still being monitored for safety and anti-tumour activity. FINDINGS: Between Jan 13, 2015, and Sept 17, 2015, we enrolled and treated 153 patients. As of the Oct 17, 2016, cutoff date, median follow-up was 17·0 months (IQR 14·8-18·8). 110 (72%) of 153 patients received all four pembrolizumab plus ipilimumab doses; 64 (42%) remained on pembrolizumab monotherapy. 110 grade 3-4 treatment-related adverse events occurred in 69 (45%) patients. No treatment-related deaths occurred. Treatment-related adverse events led to discontinuation of pembrolizumab and ipilimumab in 22 (14%) patients, including 17 (11%) who discontinued both treatments for the same event and five (3%) who discontinued ipilimumab for one event and later discontinued pembrolizumab for another. 12 (8%) patients discontinued ipilimumab only and 14 (9%) discontinued pembrolizumab only because of treatment-related adverse events. 158 immune-mediated adverse events of any grade occurred in 92 (60%) patients, and 50 immune-mediated adverse events of grade 3-4 occurred in 42 (27%) patients; the most common immune-mediated adverse events were hypothyroidism (25 [16%]) and hyperthyroidism (17 [11%]). 93 (61% [95% CI 53-69]) patients achieved an objective response. Estimated 1 year progression-free survival was 69% (95% CI 60-75), and estimated 1 year overall survival was 89% (95% CI 83-93). INTERPRETATION: Standard-dose pembrolizumab given in combination with four doses of reduced-dose ipilimumab followed by standard-dose pembrolizumab has a manageable toxicity profile and provides robust anti-tumour activity in patients with advanced melanoma. These data suggest that standard-dose pembrolizumab plus reduced-dose ipilimumab might be a tolerable, efficacious treatment option for patients with advanced melanoma. A randomised phase 2 trial of alternative dosing strategies of this combination is underway. FUNDING: Merck & Co, Inc.

Programmed death ligand 1 expression in triple-negative breast cancer is associated with tumour-infiltrating lymphocytes and improved outcome.

AIMS: Triple-negative breast cancer (TNBC) patients generally have a poor outcome; there is a pressing need to identify more effective therapeutic strategies. Clinical trials targeting programmed death 1/programmed death ligand 1 (PD1/PDL1) in melanoma and non-small-cell lung cancer have reported high response rates, and tumoral PDL1 expression has been suggested as a potential biomarker to enrich for patient response to these treatments. There are only very limited data to date reporting the expression of PDL1 in TNBC. METHODS AND RESULTS: PDL1 immunohistochemistry was performed on 161 primary TNBCs and assessed in the tumour as well as immune cells in the stromal compartment. PDL1 expression was very common in TNBC, expressed in the tumour cell membrane (64%), cytoplasm (80%) and stromal (93%) cellular compartments. Cytoplasmic tumoral expression of PDL1 was associated with a lower risk of breast cancer-specific death [hazard ratio (HR) 0.45, P = 0.035] while stromal PDL1 expression was associated with a lower rate of deaths from all causes (HR 0.305, P = 0.0042). Membranous expression of PDL1 was not associated with outcome. While both PDL1 expression and tumour-infiltrating lymphocytes were associated with a better outcome, only lymphovascular invasion and high tumour-infiltrating lymphocytes were independently prognostic for breast cancer-specific death. CONCLUSION: While PDL1 expression is frequent in TNBC, it was not independently prognostic. There were differences in outcome depending on the cellular compartment of PDL1 expression. These data provide further impetus for investigating the utility of immune checkpoint therapies in TNBC, given the clinical significance of tumour-infiltrating lymphocytes (TILs) and PDL1 expression in this cohort.

Recruitment of regulatory T cells is correlated with hypoxia-induced CXCR4 expression, and is associated with poor prognosis in basal-like breast cancers.

INTRODUCTION: Basal-like breast cancers behave more aggressively despite the presence of a dense lymphoid infiltrate. We hypothesised that immune suppression in this subtype may be due to T regulatory cells (Treg) recruitment driven by hypoxia-induced up-regulation of CXCR4 in Treg. METHODS: Immunoperoxidase staining for FOXP3 and CXCL12 was performed on tissue microarrays from 491 breast cancers. The hypoxia-associated marker carbonic anhydrase IX (CA9) and double FOXP3/CXCR4 staining were performed on sections from a subset of these cancers including 10 basal-like and 11 luminal cancers matched for tumour grade. RESULTS: High Treg infiltration correlated with tumour CXCL12 positivity (OR 1.89, 95% CI 1.22 to 2.94, P = 0.004) and basal phenotype (OR 3.14, 95% CI 1.08 to 9.17, P = 0.004) in univariate and multivariate analyses. CXCL12 positivity correlated with improved survival (P = 0.005), whereas high Treg correlated with shorter survival for all breast cancers (P = 0.001), luminal cancers (P < 0.001) and basal-like cancers (P = 0.040) that were confirmed in a multivariate analysis (OR 1.61, 95% CI 1.02 to 2.53, P = 0.042). In patients treated with hormone therapy, high Treg were associated with a shorter survival in a multivariate analysis (OR 1.78, 95% CI 1.01 to 3.15, P = 0.040). There was a tendency for luminal cancers to show CXCL12 expression (102/138, 74%) compared to basal-like cancers (16/27, 59%), which verged on statistical significance (P = 0.050). Up-regulation of CXCR4 in Treg correlated with the basal-like phenotype (P = 0.029) and tumour hypoxia, as indicated by CA9 expression (P = 0.049). CONCLUSIONS: Our data show that in the setting of hypoxia and CXCR4 up-regulation in Treg, CXCL12 expression may have the negative consequence of enhancing Treg recruitment and suppressing the anti-tumour immune response.

The expression of the ubiquitin ligase SIAH2 (seven in absentia homolog 2) is mediated through gene copy number in breast cancer and is associated with a basal-like phenotype and p53 expression.

INTRODUCTION: The seven in absentia homolog 2 (SIAH2) protein plays a significant role in the hypoxic response by regulating the abundance of hypoxia-inducible factor-α; however, its role in breast carcinoma is unclear. We investigated the frequency and expression pattern of SIAH2 in two independent cohorts of sporadic breast cancers. METHODS: Immunohistochemical evaluation of SIAH2protein expression was conducted in normal breast tissues and in tissue microarrays comprising ductal carcinoma in situ (DCIS) and a cohort of invasive breast carcinomas. Correlation analysis was performed between SIAH2 and clinicopathological variables and intrinsic breast cancer subgroups and validated in a cohort of 293 invasive ductal carcinomas. Promoter methylation, gene copy number and mRNA expression of SIAH2 were determined in a panel of basal-like tumors and cell lines. RESULTS: There was a significant increase in nuclear SIAH2 expression from normal breast tissues through to DCIS and progression to invasive cancers. A significant inverse correlation was apparent between SIAH2 and estrogen receptor and progesterone receptor and a positive association with tumor grade, HER2, p53 and an intrinsic basal-like subtype. Logistic regression analysis confirmed the significant positive association between SIAH2 expression and the basal-like phenotype. No SIAH2 promoter methylation was identified, yet there was a significant correlation between SIAH2 mRNA and gene copy number. SIAH2-positive tumors were associated with a shorter relapse-free survival in univariate but not multivariate analysis. CONCLUSIONS: SIAH2 expression is upregulated in basal-like breast cancers via copy number changes and/or transcriptional activation by p53 and is likely to be partly responsible for the enhanced hypoxic drive through abrogation of the prolyl hydroxylases.

Enhanced RAD21 cohesin expression confers poor prognosis and resistance to chemotherapy in high grade luminal, basal and HER2 breast cancers.

INTRODUCTION: RAD21 is a component of the cohesin complex, which is essential for chromosome segregation and error-free DNA repair. We assessed its prognostic and predictive power in a cohort of in situ and invasive breast cancers, and its effect on chemosensitivity in vitro. METHODS: RAD21 immunohistochemistry was performed on 345 invasive and 60 pure in situ carcinomas. Integrated genomic and transcriptomic analyses were performed on a further 48 grade 3 invasive cancers. Chemosensitivity was assessed in breast cancer cell lines with an engineered spectrum of RAD21 expression. RESULTS: RAD21 expression correlated with early relapse in all patients (hazard ratio (HR) 1.74, 95% confidence interval (CI) 1.06 to 2.86, P = 0.029). This was due to the effect of grade 3 tumors (but not grade 1 or 2) in which RAD21 expression correlated with early relapse in luminal (P = 0.040), basal (P = 0.018) and HER2 (P = 0.039) groups. In patients treated with chemotherapy, RAD21 expression was associated with shorter overall survival (P = 0.020). RAD21 mRNA expression correlated with DNA copy number, with amplification present in 32% (7/22) of luminal, 31% (4/13) of basal and 22% (2/9) of HER2 grade 3 cancers. Variations in RAD21 mRNA expression in the clinical samples were reflected in the gene expression data from 36 breast cancer cell lines. Knockdown of RAD21 in the MDA-MB-231 breast cancer cell line significantly enhanced sensitivity to cyclophosphamide, 5-fluorouracil and etoposide. The findings for the former two drugs recapitulated the clinical findings. CONCLUSIONS: RAD21 expression confers poor prognosis and resistance to chemotherapy in high grade luminal, basal and HER2 breast cancers. RAD21 may be a novel therapeutic target.

Novel Clinician-Lead Intervention to Address Fear of Cancer Recurrence in Breast Cancer Survivors.

PURPOSE: Fear of cancer recurrence (FCR) affects 50%-70% of cancer survivors. This multicenter, single-arm study sought to determine the participant-rated usefulness of an oncologist-delivered FCR intervention. METHODS: Women who completed treatment for early breast cancer (could be receiving endocrine therapy) with baseline FCR > 0 were invited to participate. FCR was measured using a validated 42-item FCR Inventory. The brief oncologist-delivered intervention entailed (1) FCR normalization; (2) provision of personalized prognostic information; (3) recurrence symptoms education, (4) advice on managing worry, and (5) referral to psycho-oncologist if FCR was high. FCR, depression, and anxiety were assessed preintervention (T0), at 1 week (T1), and 3 months (T2) postintervention. The primary outcome was participant-rated usefulness. Secondary outcomes included feasibility and efficacy. RESULTS: Five oncologists delivered the intervention to 61/255 women invited. Mean age was 58 ± 12 years. Mean time since breast cancer diagnosis was 2.5 ± 1.3 years. Forty-three women (71%) were on adjuvant endocrine therapy. Of 58 women who completed T1 assessment, 56 (97%) found the intervention to be useful. FCR severity decreased significantly at T1 (F = 18.5, effect size = 0.39, P < .0001) and T2 (F = 24, effect size = 0.68, P < .0001) compared with baseline. There were no changes in unmet need or depression or anxiety. Mean consultation length was 22 minutes (range, 7-47 minutes), and mean intervention length was 8 minutes (range, 2-20 minutes). The intervention was perceived as useful and feasible by oncologists. CONCLUSION: A brief oncologist-delivered intervention to address FCR is useful and feasible, and has preliminary efficacy in reducing FCR. Plans for a cluster randomized trial are underway.

PI3K pathway activation in breast cancer is associated with the basal-like phenotype and cancer-specific mortality.

Breast cancer is a common malignancy with current biological therapies tailored to steroid hormone (ER, PR) and HER2 receptor status. Understanding the biological basis of resistance to current targeted therapies and the identification of new potential therapeutic targets is an ongoing challenge. The PI3K pathway is altered in a high proportion of breast cancers and may contribute to therapeutic resistance. We undertook an integrative study of mutational, copy number and expression analyses of key regulators of the PI3K pathway in a cohort of 292 invasive breast cancer patients with known treatment outcomes. The alterations identified in this cohort included PIK3CA mutations (12/168, i.e. 7%), PIK3CA copy number gain (28/209, i.e. 14%), PTEN loss (73/258, i.e. 28%) and AKT activation (62/258, i.e. 24%). Overall at least 1 parameter was altered in 72% (139/193) of primary breast cancers. PI3K pathway activation was significantly associated with ER negative (p = 0.0008) and PR negative (p = 0.006) status, high tumor grade (p = 0.032) and a "basal-like" phenotype (p = 0.01), where 92% (25/27) of tumors had an altered pathway. In univariate analysis, PI3K pathway aberrations were associated with death from breast cancer; however, this relationship was not maintained in multivariate analysis. No association was identified between an activated pathway and outcome in tamoxifen- or chemotherapy-treated patients. We concluded that >70% of breast cancers have an alteration in at least 1 component of the PI3K pathway and this might be exploited to therapeutic advantage especially in "basal-like" cancers.

Loss of STARD10 expression identifies a group of poor prognosis breast cancers independent of HER2/Neu and triple negative status.

The phospholipid transfer protein STARD10 cooperates with c-erbB signaling and is overexpressed in Neu/ErbB2 breast cancers. We investigated if STARD10 expression provides additional prognostic information to HER2/neu status in primary breast cancer. A published gene expression dataset was used to determine relationships between STARD10 and HER2 mRNA levels and patient outcome. The central findings were independently validated by immunohistochemistry in a retrospective cohort of 222 patients with breast cancer with a median follow-up of 64 months. Kaplan-Meier and Cox proportional hazards analyses were used for univariate and multivariate analyses. Patients with low STARD10 or high HER2 tumor mRNA levels formed discrete groups each associated with a poor disease-specific survival (p = 0.0001 and p = 0.0058, respectively). In the immunohistochemical study low/absent STARD10 expression i.e. < or = 10% positive cells was observed in 24 of 222 (11%) tumors. In a univariate model, low/absent STARD10 expression was significantly associated with decreased patient survival (p = 0.0008). In multivariate analyses incorporating tumor size, tumor grade, lymph node status, ER, PR and HER2 status, low STARD10 expression was an independent predictor of death from breast cancer (HR: 2.56 (95% CI: 1.27-5.18), p = 0.0086). Furthermore, low/absent STARD10 expression, HER2 amplification and triple negative status were independent prognostic variables. Loss of STARD10 expression may provide an additional marker of poor outcome in breast cancer identifying a subgroup of patients with a particularly adverse prognosis, which is independent of HER2 amplification and the triple negative phenotype.

High Notch1 protein expression is an early event in breast cancer development and is associated with the HER-2 molecular subtype.

AIMS: Activation of Notch signalling results in hyperplasia and tumorigenesis in murine mammary epithelium. However, there is little information regarding the expression of Notch1 in premalignant lesions and early breast cancer. We investigated expression of Notch1 in breast cancer development and its association with molecular subtypes. METHODS AND RESULTS: Immunohistochemical expression of Notch1 was determined in a murine model of mammary carcinogenesis and in breast tissue from two cohorts of breast cancer patients, the first (n=222) comprising a histological progression series and the second an outcome series of 228 patients with operable invasive ductal carcinoma. Enhanced expression of Notch1 protein was an early event in both murine and human breast cancer development with progressive increases in expression with the development of hyperplasia and malignancy. High Notch1 was not prognostic in the outcome cohort. There was, however, a highly significant association of high Notch1 protein with the HER-2 molecular subtype of breast cancer (P=0.008). CONCLUSIONS: These data demonstrate that aberrant Notch regulation is an early event in mammary carcinogenesis and is associated with the HER-2 molecular subtype of breast cancer, and suggest the Notch signalling pathway may be a potential therapeutic target worthy of further investigation.

Long-term Follow-up of Standard-Dose Pembrolizumab Plus Reduced-Dose Ipilimumab in Patients with Advanced Melanoma: KEYNOTE-029 Part 1B.

PURPOSE: Combination therapy with reduced-dose programmed death 1 inhibitor plus standard-dose cytotoxic T-lymphocyte-associated antigen 4 inhibitor demonstrated efficacy, but substantial toxicity, in melanoma. We present long-term results of part 1B of KEYNOTE-029, which assessed safety and efficacy of standard-dose pembrolizumab plus reduced-dose ipilimumab in advanced melanoma. PATIENTS AND METHODS: Part 1B was an expansion cohort of the open-label, phase Ib portion of KEYNOTE-029. Eligible patients had advanced melanoma and no previous immune checkpoint inhibitor therapy. Patients received pembrolizumab 2 mg/kg (amended to 200 mg) every 3 weeks plus ipilimumab 1 mg/kg every 3 weeks (four cycles), then pembrolizumab alone for up to 2 years. Primary end point was safety; secondary end points included objective response rate (ORR), progression-free survival (PFS), duration of response (DOR), and overall survival (OS). RESULTS: A total of 153 patients received at least one dose of pembrolizumab plus ipilimumab. At a median follow-up of 36.8 months, 71.9% had received four doses of ipilimumab and 30.7% had completed 2 years of pembrolizumab; 26.1% completed both treatments. Treatment-related adverse events occurred in 96.1% (47.1% grade 3/4; no deaths), leading to discontinuation of one or both study drugs in 35.9%. ORR was 62.1% with 42 (27.5%) complete and 53 (34.6%) partial responses. Median DOR was not reached; 36-month ongoing response rate was 84.2%. Median PFS and OS were not reached; 36-month rates were 59.1% and 73.4%, respectively. CONCLUSIONS: Standard-dose pembrolizumab plus reduced-dose ipilimumab demonstrated robust antitumor activity, durable response, and favorable long-term survival with manageable toxicity.