Adjuvant Nivolumab versus Placebo in Muscle-Invasive Urothelial Carcinoma.

BACKGROUND: The role of adjuvant treatment in high-risk muscle-invasive urothelial carcinoma after radical surgery is not clear. METHODS: In a phase 3, multicenter, double-blind, randomized, controlled trial, we assigned patients with muscle-invasive urothelial carcinoma who had undergone radical surgery to receive, in a 1:1 ratio, either nivolumab (240 mg intravenously) or placebo every 2 weeks for up to 1 year. Neoadjuvant cisplatin-based chemotherapy before trial entry was allowed. The primary end points were disease-free survival among all the patients (intention-to-treat population) and among patients with a tumor programmed death ligand 1 (PD-L1) expression level of 1% or more. Survival free from recurrence outside the urothelial tract was a secondary end point. RESULTS: A total of 353 patients were assigned to receive nivolumab and 356 to receive placebo. The median disease-free survival in the intention-to-treat population was 20.8 months (95% confidence interval [CI], 16.5 to 27.6) with nivolumab and 10.8 months (95% CI, 8.3 to 13.9) with placebo. The percentage of patients who were alive and disease-free at 6 months was 74.9% with nivolumab and 60.3% with placebo (hazard ratio for disease recurrence or death, 0.70; 98.22% CI, 0.55 to 0.90; P<0.001). Among patients with a PD-L1 expression level of 1% or more, the percentage of patients was 74.5% and 55.7%, respectively (hazard ratio, 0.55; 98.72% CI, 0.35 to 0.85; P<0.001). The median survival free from recurrence outside the urothelial tract in the intention-to-treat population was 22.9 months (95% CI, 19.2 to 33.4) with nivolumab and 13.7 months (95% CI, 8.4 to 20.3) with placebo. The percentage of patients who were alive and free from recurrence outside the urothelial tract at 6 months was 77.0% with nivolumab and 62.7% with placebo (hazard ratio for recurrence outside the urothelial tract or death, 0.72; 95% CI, 0.59 to 0.89). Among patients with a PD-L1 expression level of 1% or more, the percentage of patients was 75.3% and 56.7%, respectively (hazard ratio, 0.55; 95% CI, 0.39 to 0.79). Treatment-related adverse events of grade 3 or higher occurred in 17.9% of the nivolumab group and 7.2% of the placebo group. Two treatment-related deaths due to pneumonitis were noted in the nivolumab group. CONCLUSIONS: In this trial involving patients with high-risk muscle-invasive urothelial carcinoma who had undergone radical surgery, disease-free survival was longer with adjuvant nivolumab than with placebo in the intention-to-treat population and among patients with a PD-L1 expression level of 1% or more. (Funded by Bristol Myers Squibb and Ono Pharmaceutical; CheckMate 274 ClinicalTrials.gov number, NCT02632409.).

Treatment of muscle-invasive urothelial cancer with nivolumab (CheckMate 274 study): a plain language summary.

WHAT IS THIS SUMMARY ABOUT?: This is a summary of a paper published in a medical journal that describes the results of a study called CheckMate 274. This study looked at a new treatment for muscle-invasive urothelial cancer, a type of cancer found in the urinary tract that has spread from the inner lining of the urinary tract or bladder and into the surrounding muscle wall where it can then spread to other parts of the body. The standard treatment for muscle-invasive urothelial cancer is surgery to remove affected parts of the urinary tract. However, cancer returns in more than half of people after this surgery. Adjuvant therapy is given to people after surgery with muscle-invasive urothelial cancer with a goal to reduce the risk of the cancer coming back; however, at the time this study started, there was no standard adjuvant treatment. WHAT HAPPENED IN THE STUDY?: In the CheckMate 274 study, researchers compared nivolumab with a placebo as an adjuvant treatment for people with muscle-invasive urothelial cancer. The aim of the study was to understand how well nivolumab worked to reduce the chance of the cancer returning after surgery. The study also looked at what side effects (unwanted or unexpected results or conditions that are possibly related to the use of a medication) people had with treatment. WHAT DO THE RESULTS MEAN?: The results showed that people who received nivolumab versus placebo: Survived longer before the cancer was detected again, including people who had programmed death ligand-1 (shortened to PD-L1) on their cancer cells. Survived longer before a secondary cancer outside of the urinary tract was detected. Experienced no differences in health-related quality of life (the impact of the treatment on a person's mental and physical health). Had similar side effects to the people who received nivolumab in other studies. Clinical Trial Registration: NCT02632409 (ClinicalTrials.gov).

Phase I clinical trial of temozolomide and methoxyamine (TRC-102), an inhibitor of base excision repair, in patients with advanced solid tumors.

Temozolomide (TMZ) generates DNA adducts that are repaired by direct DNA and base excision repair mechanisms. Methoxyamine (MX, TRC-102) potentiates TMZ activity by binding to apurinic and apyrimidinic (AP) sites after removal of N3-methyladenine and N7-methylguanine, inhibiting site recognition of AP endonuclease. We conducted a phase I trial to determine the maximum tolerated dose and dose-limiting toxicities (DLTs) of intravenous MX when given with oral TMZ. Patients with advanced solid tumors and progression on standard treatment were enrolled to a standard 3 + 3 dose escalation trial assessing escalating doses of TMZ and MX. Tumor response was assessed per RECIST and adverse events (AEs) by CTCAEv3. Pharmacokinetics (PK) of MX and COMET assays on peripheral blood mononuclear cells were performed. 38 patients were enrolled-median age 59.5 years (38-76), mean number of cycles 2.9 [1-13]. No DLTs were observed. Cycle 1 grade 3 AEs included fatigue, lymphopenia, anemia, INR, leukopenia, neutropenia, allergic reaction, constipation, psychosis and paranoia. Cycle 2-13 grade 4 AEs included thrombocytopenia and confusion. A partial response was seen in 1 patient with a pancreatic neuroendocrine tumor (PNET) and six additional patients, each with different tumor types, demonstrated prolonged stable disease. MX PK was linear with dose and was not affected by concomitant TMZ. TMZ 200 mg/m2 daily × 5 may be safely administered with MX 150 mg/m2 intravenously once on day 1 with minimal toxicity. Further studies assessing this drug combination in select tumor types where temozolomide has activity may be warranted.

Bempegaldesleukin plus nivolumab in untreated, unresectable or metastatic melanoma: Phase III PIVOT IO 001 study design.

Nivolumab, a PD-1 inhibitor, has demonstrated prolonged survival benefit in patients with advanced melanoma. Bempegaldesleukin (BEMPEG; NKTR-214), a first-in-class CD122-preferential IL-2 pathway agonist, provides sustained signaling through the IL-2ßγ receptor, which activates effector T and natural killer cells. In the Phase I/II PIVOT-02 trial, the combination of bempegaldesleukin plus nivolumab was well-tolerated and demonstrated clinical activity as first-line therapy in metastatic melanoma. Here, we describe the design of and rationale for the Phase III, global, randomized, open-label PIVOT IO 001 trial comparing bempegaldesleukin plus nivolumab with nivolumab alone in patients with previously untreated, unresectable or metastatic melanoma. Primary end points include objective response rate, progression-free survival and overall survival. Key secondary end points include further investigation of safety/tolerability, previously assessed in the PIVOT-02 trial. Clinical Trial Registration: NCT03635983 (ClinicalTrials.gov).

Immune checkpoint inhibitor-induced sarcoidosis-like granulomas.

Immune checkpoint inhibitors targeting the cytotoxic T lymphocyte-associated antigen-4 and programmed cell death-1 receptors have transformed the treatment of melanoma and other cancers. These therapies are associated with a number of side effects, including immune-related adverse events. Sarcoidosis-like granulomas (SLGs) are important immune checkpoint inhibitor-related reactions to recognize as SLGs can mimic disease progression and accordingly impact treatment decisions. We systematically review reports of immune checkpoint inhibitor-induced SLGs in cancer patients and discuss potential underlying pathophysiological mechanisms.

Soft Tissue Sarcoma, Version 2.2018, NCCN Clinical Practice Guidelines in Oncology.

Soft tissue sarcomas (STS) are rare solid tumors of mesenchymal cell origin that display a heterogenous mix of clinical and pathologic characteristics. STS can develop from fat, muscle, nerves, blood vessels, and other connective tissues. The evaluation and treatment of patients with STS requires a multidisciplinary team with demonstrated expertise in the management of these tumors. The complete NCCN Guidelines for STS provide recommendations for the diagnosis, evaluation, and treatment of extremity/superficial trunk/head and neck STS, as well as intra-abdominal/retroperitoneal STS, gastrointestinal stromal tumors, desmoid tumors, and rhabdomyosarcoma. This portion of the NCCN Guidelines discusses general principles for the diagnosis, staging, and treatment of STS of the extremities, superficial trunk, or head and neck; outlines treatment recommendations by disease stage; and reviews the evidence to support the guidelines recommendations.

A phase 2 trial of dasatinib in patients with locally advanced or stage IV mucosal, acral, or vulvovaginal melanoma: A trial of the ECOG-ACRIN Cancer Research Group (E2607).

BACKGROUND: KIT-directed tyrosine kinase inhibitors such as imatinib have demonstrated benefits in KIT-mutant (KIT+) mucosal, acral, vulvovaginal, and chronically sun-damaged (CSD) melanoma. Dasatinib has superior preclinical activity in comparison with other tyrosine kinase inhibitors against cells with the most common KIT mutation, exon 11L576P . The ECOG-ACRIN E2607 trial assessed dasatinib in patients with these melanoma subtypes. METHODS: Patients received 70 mg of oral dasatinib twice daily. The primary objective for this 2-stage phase 2 trial was response rate. Stage I was open to KIT+ and wild-type KIT (KIT-) mucosal, acral, and CSD melanoma (n = 57). Stage II accrued only KIT+ tumors (n = 30). To enrich the trial for KIT+ tumors, vulvovaginal melanoma was added, and CSD melanoma was removed from eligibility. Secondary objectives included progression-free survival (PFS), overall survival (OS), and safety. RESULTS: From May 2009 to December 2010, the first stage enrolled 57 patients. Among the evaluable patients, 3 of 51 (5.9%) achieved a partial response: all were KIT-. Stage II closed early because of slow accrual (November 2011 to December 2015). In stage II, 4 of 22 evaluable patients (18.2%) had a partial response; the median duration was 4.2 months. The median PFS was 2.1 months (n = 73; 95% confidence interval [CI], 1.5-2.9 months). The median OS was 7.5 months (95% CI, 6.0-11.9 months). In exploratory analyses, no differences were seen in PFS or OS with the KIT status or subtype. Dasatinib was discontinued because of adverse events in 9 of 75 patients (12%). CONCLUSIONS: The dasatinib response rate among KIT+ melanoma patients was low. In view of its clinical activity, it is recommended that imatinib remain the KIT tyrosine kinase inhibitor of choice for unresectable KIT+ melanoma. Cancer 2017;123:2688-97. © 2017 American Cancer Society.

Soft Tissue Sarcoma, Version 2.2016, NCCN Clinical Practice Guidelines in Oncology.

Soft tissue sarcomas (STS) are rare solid tumors of mesenchymal cell origin that display a heterogenous mix of clinical and pathologic characteristics. STS can develop from fat, muscle, nerves, blood vessels, and other connective tissues. The evaluation and treatment of patients with STS requires a multidisciplinary team with demonstrated expertise in the management of these tumors. The complete NCCN Guidelines for Soft Tissue Sarcoma (available at NCCN.org) provide recommendations for the diagnosis, evaluation, and treatment of extremity/superficial trunk/head and neck STS, as well as intra-abdominal/retroperitoneal STS, gastrointestinal stromal tumor, desmoid tumors, and rhabdomyosarcoma. This manuscript discusses guiding principles for the diagnosis and staging of STS and evidence for treatment modalities that include surgery, radiation, chemoradiation, chemotherapy, and targeted therapy.

Update on primary mucosal melanoma.

Mucosal melanomas are aggressive cancers of mucosal surfaces with clinical and pathologic characteristics distinct from cutaneous melanomas, warranting different staging systems and treatment approaches. Surgical resection is performed frequently for the primary tumor, although the utility of lymph node surgery and radiation therapy is not established. Therapies targeted against C-KIT activating mutations, identified in many mucosal melanomas, are emerging as promising treatments.

What is the role of chemotherapy in the treatment of melanoma?

The approval of ipilimumab and inhibitors of the BRAF pathway for the treatment of melanoma has provided multiple therapeutic options for patients. Although these new agents improve survival compared with chemotherapy alone, the majority of patients will progress and will receive chemotherapy at some point in the course of their disease. Whether the clinical efficacy of chemotherapy can be improved by targeting resistance mechanisms is an area of active investigation. In addition, chemotherapy may be of use modulating the efficacy of the newer agents.

Current systemic therapies for melanoma.

BACKGROUND: Systemic agents are used in melanoma for adjuvant therapy and to treat metastatic disease. Currently, interferon-α is the only agent approved for adjuvant therapy. Six drugs are FDA approved for metastatic disease: dacarbazine, interleukin-2 (IL-2), vemurafenib, ipilimumab, dabrafenib, and trametinib. Vemurafenib and ipilimumab were approved in 2011, whereas dabrafenib and trametinib were approved in 2013. OBJECTIVE: This review will update the practicing dermatologist on the differences in efficacy, adverse events, and cost of systemic therapies available for the treatment of melanoma. MATERIALS AND METHODS: This article is a review of the current literature on systemic therapies for advanced melanoma. Key search words included "advanced melanoma," "systemic therapy," and "adjuvant therapy" with particular focus on the past 20 years. RESULTS: Before 2011, dacarbazine and IL-2 were the only FDA approved therapies for metastatic melanoma, and IFN-α is the only approved agent for adjuvant therapy. The new agents vemurafenib, ipilimumab, dabrafenib, and trametinib are the first to have improved overall survival in Phase III studies in comparison with other systemic therapies. CONCLUSION: Despite new developments, there remains a significant need for better therapies with improved long-term efficacy and decreased toxicity.

CpG methylation as a tool to characterize cell-free Kaposi sarcoma herpesvirus DNA.

We studied the presence of Kaposi sarcoma herpesvirus sequences in cell-free DNA (cfDNA) isolated from the blood of patients with AIDS-related Kaposi sarcoma (KS) and primary effusion lymphoma (PEL). The use of paramagnetic beads linked to methyl-CpG binding domain protein allowed separation of virion and cell-derived DNA. Only virion DNA was detected in the blood of KS patients, whereas cell-derived DNA was detected in a patient with AIDS-related PEL. The difference in the origins of cfDNA in these settings may in part reflect very different proliferative indices in KS and PEL tumor tissue.

Immune adverse events (irAEs) with adjuvant ipilimumab in melanoma, use of immunosuppressants and association with outcome: ECOG-ACRIN E1609 study analysis.

BACKGROUND: The impact of immune-related adverse events (irAEs) occurring from adjuvant use of immunotherapy and of their management on relapse-free survival (RFS) and overall survival (OS) outcomes is currently not well understood. PATIENTS AND METHODS: E1609 enrolled 1673 patients with resected high-risk melanoma and evaluated adjuvant ipilimumab 3 mg/kg (ipi3) and 10 mg/kg (ipi10) versus interferon-α. We investigated the association of irAEs and of use of immunosuppressants with RFS and OS for patients treated with ipilimumab (n=1034). RESULTS: Occurrence of grades 1-2 irAEs was associated with RFS (5 years: 52% (95% CI 47% to 56%) vs 41% (95% CI 31% to 50%) with no AE; p=0.006) and a trend toward improved OS (5 years: 75% (95% CI 71% to 79%) compared with 67% (95% CI 56% to 75%) with no AE; p=0.064). Among specific irAEs, grades 1-2 rash was most significantly associated with RFS (p=0.002) and OS (p=0.003). In multivariate models adjusting for prognostic factors, the most significant associations were seen for grades 1-2 rash with RFS (p<0.001, HR=0.70) and OS (p=0.01, HR=0.71) and for grades 1-2 endocrine+rash with RFS (p<0.001, HR=0.66) and OS (p=0.008, HR=0.7). Overall, grades 1-2 irAEs had the best prognosis in terms of RFS and OS and those with grades 3-4 had less RFS benefits and no OS advantage over no irAE. Patients experiencing grades 3-4 irAE had significantly higher exposure to corticosteroids and immunosuppressants than those with grades 1-2 (92% vs 60%; p<0.001), but no significant associations were found between corticosteroid and immunosuppressant use and RFS or OS. In investigating the impact of non-corticosteroid immunosuppressants, although there were trends toward better RFS and OS favoring cases who were not exposed, no significant associations were found. CONCLUSIONS: Rash and endocrine irAEs were independent prognostic factors of RFS and OS in patients treated with adjuvant ipilimumab. Patients experiencing lower grade irAEs derived the most benefit, but we found no significant evidence supporting a negative impact of high dose corticosteroids and immunosuppressants more commonly used to manage grades 3-4 irAEs.

Evaluation of six CTLA-4 polymorphisms in high-risk melanoma patients receiving adjuvant interferon therapy in the He13A/98 multicenter trial.

PURPOSE: Interferon is approved for adjuvant treatment of patients with stage IIb/III melanoma. The toxicity and uncertainty regarding survival benefits of interferon have qualified its acceptance, despite significant durable relapse prevention in a fraction of patients. Predictive biomarkers that would enable selection of patients for therapy would have a large impact upon clinical practice. Specific CTLA-4 polymorphisms have previously shown an association with response to CTLA-4 blockade in patients with metastatic melanoma and the development of autoimmunity. EXPERIMENTAL DESIGN: 286 melanoma patients and 288 healthy controls were genotyped for six CTLA-4 polymorphisms previously suggested to be important (AG 49, CT 318, CT 60, JO 27, JO30 and JO 31). Specific allele frequencies were compared between the healthy and patient populations, as well as presence or absence of these in relation to recurrence. Alleles related to autoimmune disease were also investigated. RESULTS: No significant differences were found between the distributions of CTLA-4 polymorphisms in the melanoma population compared with healthy controls. Relapse free survival (RFS) and overall survival (OS) did not differ significantly between patients with the alleles represented by these polymorphisms. No correlation between autoimmunity and specific alleles was shown. The six polymorphisms evaluated where strongly associated (Fisher's exact p-values < 0.001 for all associations) and significant linkage disequilibrium among these was indicated. CONCLUSION: No polymorphisms of CTLA-4 defined by the SNPs studied were correlated with improved RFS, OS, or autoimmunity in this high-risk group of melanoma patients.

Evolving impact of long-term survival results on metastatic melanoma treatment.

Melanoma treatment has been revolutionized over the past decade. Long-term results with immuno-oncology (I-O) agents and targeted therapies are providing evidence of durable survival for a substantial number of patients. These results have prompted consideration of how best to define long-term benefit and cure. Now more than ever, oncologists should be aware of the long-term outcomes demonstrated with these newer agents and their relevance to treatment decision-making. As the first tumor type for which I-O agents were approved, melanoma has served as a model for other diseases. Accordingly, discussions regarding the value and impact of long-term survival data in patients with melanoma may be relevant in the future to other tumor types. Current findings indicate that, depending on the treatment, over 50% of patients with melanoma may gain durable survival benefit. The best survival outcomes are generally observed in patients with favorable prognostic factors, particularly normal baseline lactate dehydrogenase and/or a low volume of disease. Survival curves from melanoma clinical studies show a plateau at 3 to 4 years, suggesting that patients who are alive at the 3-year landmark (especially in cases in which treatment had been stopped) will likely experience prolonged cancer remission. Quality-of-life and mixture-cure modeling data, as well as metrics such as treatment-free survival, are helping to define the value of this long-term survival. In this review, we describe the current treatment landscape for melanoma and discuss the long-term survival data with immunotherapies and targeted therapies, discussing how to best evaluate the value of long-term survival. We propose that some patients might be considered functionally cured if they have responded to treatment and remained treatment-free for at least 2 years without disease progression. Finally, we consider that, while there have been major advances in the treatment of melanoma in the past decade, there remains a need to improve outcomes for the patients with melanoma who do not experience durable survival.

Phase III Study of Adjuvant Ipilimumab (3 or 10 mg/kg) Versus High-Dose Interferon Alfa-2b for Resected High-Risk Melanoma: North American Intergroup E1609.

PURPOSE: Phase III adjuvant trials have reported significant benefits in both relapse-free survival (RFS) and overall survival (OS) for high-dose interferon alfa (HDI) and ipilimumab at 10 mg/kg (ipi10). E1609 evaluated the safety and efficacy of ipilimumab at 3 mg/kg (ipi3) and ipi10 versus HDI. PATIENTS AND METHODS: E1609 was a phase III trial in patients with resected cutaneous melanoma (American Joint Committee on Cancer 7th edition stage IIIB, IIIC, M1a, or M1b). It had 2 coprimary end points: OS and RFS. A 2-step hierarchic approach first evaluated ipi3 versus HDI followed by ipi10 versus HDI. RESULTS: Between May 2011 and August 2014, 1,670 adult patients were centrally randomly assigned (1:1:1) to ipi3 (n = 523), HDI (n = 636), or ipi10 (n = 511). Treatment-related adverse events grade ≥ 3 occurred in 37% of patients receiving ipi3, 79% receiving HDI, and 58% receiving ipi10, with adverse events leading to treatment discontinuation in 35%, 20%, and 54%, respectively. Comparison of ipi3 versus HDI used an intent-to-treat analysis of concurrently randomly assigned patient cases (n = 1,051) and showed significant OS difference in favor of ipi3 (hazard ratio [HR], 0.78; 95.6% repeated CI, 0.61 to 0.99; P = .044; RFS: HR, 0.85; 99.4% CI, 0.66 to 1.09; P = .065). In the second step, for ipi10 versus HDI (n = 989), trends in favor of ipi10 did not achieve statistical significance. Salvage patterns after melanoma relapse showed significantly higher rates of ipilimumab and ipilimumab/anti-programmed death 1 use in the HDI arm versus ipi3 and ipi10 (P ≤ .001). CONCLUSION: Adjuvant therapy with ipi3 benefits survival versus HDI; for the first time to our knowledge in melanoma adjuvant therapy, E1609 has demonstrated a significant improvement in OS against an active control regimen. The currently approved adjuvant ipilimumab dose (ipi10) was more toxic and not superior in efficacy to HDI.

Rational design of anti-GITR-based combination immunotherapy.

Modulating T cell homeostatic mechanisms with checkpoint blockade can efficiently promote endogenous anti-tumor T cell responses1-11. However, many patients still do not benefit from checkpoint blockade12, highlighting the need for targeting of alternative immune pathways13. Glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) is an attractive target for immunotherapy, owing to its capacity to promote effector T cell (Teff) functions14,15 and hamper regulatory T cell (Treg) suppression16-20. On the basis of the potent preclinical anti-tumor activity of agonist anti-GITR antibodies, reported by us and others16,21,22, we initiated the first in-human phase 1 trial of GITR agonism with the anti-GITR antibody TRX518 ( NCT01239134 ). Here, we report the safety profile and immune effects of TRX518 monotherapy in patients with advanced cancer and provide mechanistic preclinical evidence to rationally combine GITR agonism with checkpoint blockade in future clinical trials. We demonstrate that TRX518 reduces circulating and intratumoral Treg cells to similar extents, providing an easily assessable biomarker of anti-GITR activity. Despite Treg reductions and increased Teff:Treg ratios, substantial clinical responses were not seen. Similarly, in mice with advanced tumors, GITR agonism was not sufficient to activate cytolytic T cells due to persistent exhaustion. We demonstrate that T cell reinvigoration with PD-1 blockade can overcome resistance of advanced tumors to anti-GITR monotherapy. These findings led us to start investigating TRX518 with PD-1 pathway blockade in patients with advanced refractory tumors ( NCT02628574 ).

Effects of the administration of high-dose interleukin-2 on immunoregulatory cell subsets in patients with advanced melanoma and renal cell cancer.

PURPOSE: High-dose recombinant human interleukin-2 (IL-2) therapy is of clinical benefit in a subset of patients with advanced melanoma and renal cell cancer. Although IL-2 is well known as a T-cell growth factor, its potential in vivo effects on human immunoregulatory cell subsets are largely unexplored. EXPERIMENTAL DESIGN: Here, we studied the effects of high-dose IL-2 therapy on circulating dendritic cell subsets (DC), CD1d-reactive invariant natural killer T cells (iNKT), and CD4(+)CD25(+) regulatory-type T cells. RESULTS: The frequency of both circulating myeloid DC1 and plasmacytoid DC decreased during high-dose IL-2 treatment. Of these, only a significant fraction of myeloid DC expressed CD1d. Although the proportion of Th1-type CD4(-) iNKT increased, similarly to DC subsets, the total frequency of iNKT decreased during high-dose IL-2 treatment. In contrast, the frequency of CD4(+)CD25(+) T cells, including CD4(+)Foxp3(+) T cells, which have been reported to suppress antitumor immune responses, increased during high-dose IL-2 therapy. However, there was little, if any, change of expression of GITR, CD30, or CTLA-4 on CD4(+)CD25(+) T cells in response to IL-2. Functionally, patient CD25(+) T cells at their peak level (immediately after the first cycle of high-dose IL-2) were less suppressive than healthy donor CD25(+) T cells and mostly failed to Th2 polarize iNKT. CONCLUSIONS: Our data show that there are reciprocal quantitative and qualitative alterations of immunoregulatory cell subsets with opposing functions during treatment with high-dose IL-2, some of which may compromise the establishment of effective antitumor immune responses.