Effect of age on safety and efficacy of novel cancer drugs investigated in early-phase clinical trials.

BACKGROUND: Elderly patients are underrepresented in clinical trials, particularly in early-phase studies. Our study assessed the safety and efficacy of novel anti-cancer treatments investigated in early-phase clinical trials, comparing outcomes between younger and elderly patients. METHODS: This retrospective study analyzed data from patients enrolled in phase I/II trials at our center between January 2014 and April 2021. We evaluated clinicopathologic characteristics, toxicity, and clinical efficacy, categorizing patients into younger (≤ 65 years) and elderly (> 65 years) groups. RESULTS: 419 patients were included with a median age of 56 years. Among these, 107 (26 %) were older than 65 years. Predominant cancers included breast (48 %), lung (10 %), and melanoma (5 %). Patients were treated in 64 trials, predominantly receiving immunotherapy-based (47 %) or targeted therapy-based (45 %) treatment. Elderly presented with poorer ECOG performance status (P = 0.001) and had fewer prior therapy lines (P = 0.01) than younger patients. Grade ≥ 3 adverse events (AEs) were similar across age groups (31 % younger vs 33 % elderly; P = 0.7), including in combination therapy scenarios. However, elderly patients experienced more AEs with antibody-drug conjugates compared to younger counterparts (56 % vs 14 %, P = 0.036) and were more likely to discontinue treatment due to toxicity (15 % vs 7 %; P = 0.011). No significant age-related differences in response rates and survival outcomes were observed across treatment modalities, except for immunotherapy-based regimens for which elderly patients exhibited higher response rates, disease control rates, and prolonged progression-free survival. CONCLUSIONS: Our findings suggest that elderly exhibit comparable safety and efficacy outcomes to younger patients in early-phase clinical trials for new cancer drugs. This underscores the importance of including elderly patients in phase I/II trials to ensure the generalizability of study results and mitigate age-related disparities in cancer treatment access.

Corrigendum: Aromatase inhibitors: the journey from the state of the art to clinical open questions.

[This corrects the article DOI: 10.3389/fonc.2023.1249160.].

Baseline Tumor Size as Prognostic Index in Patients With Advanced Solid Tumors Receiving Experimental Targeted Agents.

BACKGROUND: Baseline tumor size (BTS) has been associated with outcomes in patients with cancer treated with immunotherapy. However, the prognostic impact of BTS on patients receiving targeted therapies (TTs) remains undetermined. METHODS: We reviewed data of patients with advanced solid tumors consecutively treated within early-phase clinical trials at our institution from 01/2014 to 04/2021. Treatments were categorized as immunotherapy-based or TT-based (biomarker-matched or not). BTS was calculated as the sum of RECIST1.1 baseline target lesions. RESULTS: A total of 444 patients were eligible; the median BTS was 69 mm (IQR 40-100). OS was significantly longer for patients with BTS lower versus higher than the median (16.6 vs. 8.2 months, P < .001), including among those receiving immunotherapy (12 vs. 7.5 months, P = .005). Among patients receiving TT, lower BTS was associated with longer PFS (4.7 vs. 3.1 months, P = .002) and OS (20.5 vs. 9.9 months, P < .001) as compared to high BTS. However, such association was only significant among patients receiving biomarker-matched TT, with longer PFS (6.2 vs. 3.3 months, P < .001) and OS (21.2 vs. 6.7 months, P < .001) in the low-BTS subgroup, despite a similar ORR (28% vs. 22%, P = .57). BTS was not prognostic among patients receiving unmatched TT, with similar PFS (3.7 vs. 4.4 months, P = .30), OS (19.3 vs. 11.8 months, P = .20), and ORR (33% vs. 28%, P = .78) in the 2 BTS groups. Multivariate analysis confirmed that BTS was independently associated with PFS (P = .03) and OS (P < .001) but not with ORR (P = .11). CONCLUSIONS: Higher BTS is associated with worse survival outcomes among patients receiving biomarker-matched, but not biomarker-unmatched TT.

Immune-Related Adverse Event Likelihood Score Identifies "Pure" IRAEs Strongly Associated With Outcome in a Phase I-II Trial Population.

BACKGROUND: Immune-related adverse events (IRAE) pose a significant diagnostic and therapeutic challenge in patients treated with immune-oncology (IO) drugs. IRAEs have been suggested to correlate with better outcome, but studies are conflicting. Estimating the true incidence of IRAEs is particularly difficult in the early phase I/II trial setting. A key issue is the lack of IRAE diagnostic criteria, necessary to discriminate "pure" IRAEs from other treatment-related adverse events not sustained by an autoimmune process. METHODS: In patients treated with immune-oncology (IO) drugs in phases I-II trials at our institute, we identified high confidence (HC) or low confidence (LC) IRAEs by clinical consensus. We empirically developed an IRAE likelihood score (ILS) based on commonly available clinical data. Correlation with outcome was explored by multivariate Cox analysis. To mitigate immortal time-bias, analyses were conducted (1) at 2-month landmark and (2) modeling IRAEs as time-dependent covariate. RESULTS: Among 202 IO-treated patients, 29.2% developed >1 treatment-related adverse events (TRAE). Based on ILS >5, we classified patients in no IRAE (n = 143), HC IRAE (n = 24), or LC IRAE (n = 35). hazard ratios (HR) for HC were significantly lower than LC patients (HR for PFS ranging 0.24-0.44, for OS 0.18-0.23, all P < .01). CONCLUSION: ILS provides a simple system to identify bona fide IRAEs, pruning for other treatment-related events likely due to different pathophysiology. Applying stringent criteria leads to lower and more reliable estimates of IRAE incidence and identifies events with significant impact on survival.

Aromatase inhibitors: the journey from the state of the art to clinical open questions.

Breast cancer is a major cause of death among females. Great advances have been made in treating this disease, and aromatase inhibitors (AIs) have been recognized as the cornerstone. They are characterized by high efficacy and low toxicity. The authors reviewed the available literature and defined state-of-the-art AI management. This study was designed to assist clinicians in addressing the need to equally weigh patients' needs and disease control rates in their everyday clinical practice. Today, AIs play a central role in the treatment of hormone receptor-positive breast cancer. In this study, an expert panel reviewed the literature on the use of AIs, discussing the evolution of their use in various aspects of breast cancer, from pre- and postmenopausal early breast cancer to metastatic breast cancer, along with their management regarding efficacy and toxicity. Given the brilliant results that have been achieved in improving survival in everyday clinical practice, clinicians need to address their concerns about therapy duration and the adverse effects they exert on bone health, the cardiovascular system, and metabolism. Currently, in addition to cancer treatment, patient engagement is crucial for improving adherence to therapy and supporting patients' quality of life, especially in a selected subset of patients, such as those receiving an extended adjuvant or combination with targeted therapies. A description of modern technologies that contribute to this important goal is provided.

Fast Mimicking Diets and Other Innovative Nutritional Interventions to Treat Patients with Breast Cancer.

The impact of nutritional patterns on the risk of breast cancer (BC) is well investigated in the oncology literature, including the type of diets and caloric intake. While obesity and elevated body mass index are well-reported critical risk factors of BC occurrence, there is an expanding area of oncology assessing the impact of caloric intake and nutritional patterns in patients with cancer. Caloric restriction and fast mimicking alimentary regimens have been consistently reported to improve survival outcomes based on preclinical models. Moreover, emerging clinical evidence has paved the way for new metabolic approaches for the treatment of BC, in addition to the established therapeutic arsenal or as alternative options. In this chapter, our aim is to discuss the principal strategies of metabolic manipulation through nutritional interventions for patients with BC as an innovative area of cancer therapy.

Safety of COVID-19 mRNA Vaccines in Patients with Cancer Enrolled in Early-Phase Clinical Trials.

Pivotal trials of COVID-19 vaccines did not include cancer patients, with questions remaining about their safety and efficacy in this population. Patients enrolled in early-phase clinical trials receive novel treatments with unknown efficacy and safety profiles. Studies on the safety of COVID-19 vaccines in these patients are urgently required. This is a retrospective, real-world, cohort study of patients receiving anticancer treatments and COVID-19 vaccines between 1 February and 25 June 2021 at the Division of New Drugs Development for Innovative Therapies of the European Institute of Oncology. One hundred thirteen patients were enrolled, 40 in early-phase clinical trials, and 20 under novel immunotherapy agents. Nearly three-quarters of the patients experienced at least one adverse event (AE) after the first dose (1D) (74.3%) and second dose (2D) (72.6%). Most of the AEs were local (67.3% 1D and 61.9% after 2D), while 31.8% (1D) and 38.1% (2D) of the patients had systemic AEs. No AEs above grade 2 were observed. Therefore, COVID-19 vaccines appear to be safe in patients enrolled in early-phase clinical trials, including patients receiving novel immunotherapy compounds. All cancer patients should be prioritized for COVID-19 vaccination, regardless of ongoing treatments or enrollment in early-phase trials.

Clinical efficacy of ribociclib as a first-line therapy for HR-positive, advanced breast cancer.

INTRODUCTION: Breast cancer (BC) remains the most frequently diagnosed cancer and the most common cause of cancer death among women of all races worldwide. Over 80% of BC cases are hormone receptor (HR)-positive, comprised of luminal A and luminal B per molecular subtypes, imposing an urgent need to fully understand the mechanisms behind progression. Ribociclib is a selective cycline-dependent kinase 4 and 6 inhibitor. A phase 1 and a phase 3 trial have established a definitive role of ribociclib as frontline in the treatment of endocrine-sensitive advanced BC. Areas covered: Herein, the authors provide an overview of the data on ribociclib covering all aspects of the drug from its pharmacokinetics to efficacy and safety. The authors also provide their perspectives for the future. Expert opinion: Ribociclib is offering an opportunity to explore a new compound at the crossroads of different molecular activity and cell targets, which focus on endocrine-resistance reversal in multiple settings including early BC. Moreover, its activity against different subtypes of BC is being studied as is its immune-modulating effect. One cautionary note is that, in a market of concomitant similar competitors, a financial discussion will be mandatory.

Entinostat for the treatment of breast cancer.

INTRODUCTION: Breast cancer accounts for 29% of malignant tumors. It is an heterogenous disease covering a spectrum of different molecular subtypes. Epigenetic aberrations may affect gene expression through DNA and histone proteins modifications thus promoting tumor progression and resistance to anti- tumor treatment. Area covered: This article explores the potential role of entinostat in the treatment of breast cancer. The clinical trials evaluating entinostat are discussed, highlighting preclinical data and early-phase clinical studies results. The emerging activity of entinostat in several clinical settings is evaluated by focusing on endocrine-resistant, HER2 positive and triple-negative breast cancer with promising activity in boosting the immune-system. Expert opinion: Entinostat, a synthetic benzamide derivative class I histone deacetylases (HDACs) inhibitor, inhibits cell proliferation and promotes apoptosis in breast cancer. Several results from clinical trials demonstrate that the addition of an epigenetic therapy to antiestrogen therapy may be an effective approach to targeting resistance pathways in breast cancer, particularly in hormone-positive disease. Agents such as entinostat may have a role in immunogenic modulation. Genetic and pharmacological inhibition studies identified HDAC as a key determinant in the reversal of carcinoma immune escape. This offers the rationale for combining HDAC inhibitors with immunotherapy, including therapeutic cancer vaccines.

Strategies to modulate the immune system in breast cancer: checkpoint inhibitors and beyond.

Is breast cancer (BC) immunogenic? Many data suggest that it is. Many observations demonstrated the prognostic role of tumor-infiltrating lymphocytes (TILs) in triple negative (TN) and human epidermal growth factor receptor 2 (HER-2)-positive BC. TNBCs are poorly differentiated tumors with high genetic instability and very high heterogeneity. This heterogeneity enhances the 'danger signals' and select clone variants that could be more antigenic or, in other words, that could more strongly stimulate a host immune antitumor response. The response to chemotherapy is at least partly dependent on an immunological reaction against those tumor cells that are dying during the chemotherapy. One of the mechanisms whereby chemotherapy can stimulate the immune system to recognize and destroy malignant cells is commonly known as immunogenic cell death (ICD). ICD elicits an adaptive immune response. Which are the clinical implications of all 'immunome' data produced in the last years? First, validate prognostic or predictive role of TILs. Second, validate immune genomic signatures that may be predictive and prognostic in patients with TN disease. Third, incorporate an 'immunoscore' into traditional classification of BC, thus providing an essential prognostic and potentially predictive tool in the pathology report. Fourth, implement clinical trials for BC in the metastatic setting with drugs that target immune-cell-intrinsic checkpoints. Blockade of one of these checkpoints, cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) or the programmed cell death 1 (PD-1) receptor may provide proof of concepts for the activity of an immune-modulation approach in the treatment of a BC.

Mechanisms of anorexia-cachexia syndrome and rational for treatment with selective ghrelin receptor agonist.

Cancer cachexia is a multi-organ, multifactorial and often irreversible syndrome affecting many patients with cancer. Cancer cachexia is invariably associated with weight loss, mainly from loss of skeletal muscle and body fat, conditioning a reduced quality of life due to asthenia, anorexia, anaemia and fatigue. Treatment options for treating cancer cachexia are limited. The approach is multimodal and may include: treatment of secondary gastrointestinal symptoms, nutritional treatments, drug, and non-drug treatments. Nutritional counselling and physical training may be beneficial in delaying or preventing the development of anorexia-cachexia. However, these interventions are limited in their effect, and no definitive pharmacological treatment is available to address the relevant components of the syndrome. Anamorelin is a first-in-class, orally active ghrelin receptor agonist that binds and stimulates the growth hormone secretagogue receptor centrally, thereby mimicking the appetite-enhancing and anabolic effects of ghrelin. It represents a new class of drug and an additional treatment option for this patient group, whose therapeutic options are currently limited. In this review we examine the mechanisms of anamorelin by which it contrasts catabolic states, its role in regulation of metabolism and energy homeostasis, the data of recent trials in the setting of cancer cachexia and its safety profile.

Dacarbazine in combination with bevacizumab for the treatment of unresectable/metastatic melanoma: a phase II study.

The combined treatment of dacarbazine with an antiangiogenic drug such as bevacizumab may potentiate the therapeutic effects of dacarbazine in metastatic melanoma (MM). Preliminary antitumour activity of dacarbazine plus bevacizumab is evaluated, together with the toxicity and safety profile, in MM patients. This prospective, open-label, phase II study included patients with previously untreated MM or unresectable melanoma. Patients received dacarbazine and bevacizumab until progressive disease or unacceptable toxicity. The primary efficacy variable was the overall response rate. The secondary efficacy parameters included duration of response, duration of stable disease, time to progression/progression-free survival, time to treatment failure and overall survival. The safety analysis included recordings of adverse events and exposure to study treatment. The intention-to-treat population included 37 patients (24 men and 13 women, mean age 54.2±13.1 years). Overall response rate was 18.9% (seven patients achieved a response) and clinical benefit was 48.6%. In patients who achieved a response, the median duration of response was 16.9 months and the median duration of stable disease was 12.5 months. The median time to progression/progression-free survival and time to treatment failure were 5.5 and 3.1 months, respectively. The median overall survival was 11.4 months. Almost all patients (94.6%) experienced at least one adverse event; however, no new area of toxicity of bevacizumab emerged. The dacarbazine/bevacizumab combination provides benefits compared with dacarbazine monotherapy in historical controls, with an acceptable safety profile. This combination appears to be a valid option in specific subgroups of patients, namely, those triple negative (BRAF, C-KIT and NRAS wild type) or with a BRAF mutation who have already received, or are not eligible for, immunomodulating or targeted agents.

QTc prolongation induced by targeted biotherapies used in clinical practice and under investigation: a comprehensive review.

In anticancer drug development, there has been increasing consideration for the potential of a compound to cause adverse electrocardiographic changes, especially QT interval prolongation, which can be associated with risk of torsades de pointes and sudden death. Irrespective of overt clinical toxicities, QTc assessment can influence decision making during the conduct of clinical studies, including eligibility for protocol therapy, dose delivery or discontinuation, and analyses of optimal dose for subsequent development. Efforts are needed to refine strategies for risk management, avoiding unintended consequences that negatively affect patient access and clinical development of promising new cancer treatments. In this comprehensive review, we will analyze potential effects on QTc prolongations of targeted agents approved by regulatory agencies and under investigation. A thoughtful risk management plan was generated by an organized collaboration between oncologists, cardiologists, and regulatory agencies to support a development program essential for oncology agents with cardiac safety concerns.

Biopsy confirmation of metastatic sites in breast cancer patients: clinical impact and future perspectives.

Determination of hormone receptor (estrogen receptor and progesterone receptor) and human epidermal growth factor receptor 2 status in the primary tumor is clinically relevant to define breast cancer subtypes, clinical outcome,and the choice of therapy. Retrospective and prospective studies suggest that there is substantial discordance in receptor status between primary and recurrent breast cancer. Despite this evidence and current recommendations,the acquisition of tissue from metastatic deposits is not routine practice. As a consequence, therapeutic decisions for treatment in the metastatic setting are based on the features of the primary tumor. Reasons for this attitude include the invasiveness of the procedure and the unreliable outcome of biopsy, in particular for biopsies of lesions at complex visceral sites. Improvements in interventional radiology techniques mean that most metastatic sites are now accessible by minimally invasive methods, including surgery. In our opinion, since biopsies are diagnostic and changes in biological features between the primary and secondary tumors can occur, the routine biopsy of metastatic disease needs to be performed. In this review, we discuss the rationale for biopsy of suspected breast cancer metastases, review issues and caveats surrounding discordance of biomarker status between primary and metastatic tumors, and provide insights for deciding when to perform biopsy of suspected metastases and which one (s) to biopsy. We also speculate on the future translational implications for biopsy of suspected metastatic lesions in the context of clinical trials and the establishment of bio-banks of biopsy material taken from metastatic sites. We believe that such bio-banks will be important for exploring mechanisms of metastasis. In the future,advances in targeted therapy will depend on the availability of metastatic tissue.

Dendritic cell-based vaccines: clinical applications in breast cancer.

Recent evidence suggests that the immune system is involved in the carcinogenesis process and the antitumor immune responses impact the clinical outcome, thus emphasizing the concept of cancer immune surveillance. In this context, dendritic cells (DCs) seem to play a crucial role, as they are the most potent antigen-presenting cells (APCs) and are able to stimulate naive T lymphocytes and to generate memory T lymphocytes. Immunotherapy with DC-based vaccines is a very attractive approach to treat cancer, offering the potential for high tumor-specific cytotoxicity. Although breast cancer (BC) is traditionally considered a poorly immunogenic tumor, increasing numbers of both preclinical and clinical studies demonstrate that vaccination with DCs is capable of inducing an antitumor-specific response, while being well tolerated and safe. However, clinical objective responses are still disappointing and many reasons may explain the difficulty of developing effective DC-based therapies for BC. In this review, we discuss the characteristics of DCs, and the major clinical indications for DC-based immunotherapy in BC with related drawbacks.

Immune approaches to the treatment of breast cancer, around the corner?

Immunotherapy for the treatment of breast cancer can be categorized as either (a) specific stimulation of the immune system by active immunization, with cancer vaccines, or (b) passive immunization, such as tumor-specific antibodies (including immune modulators) or adoptive cell therapy that inhibit the function of, or directly kill, tumor cells. We will present the current information and the future perspectives of immunotherapy in patients with breast cancer, including the prognostic role of tumor infiltrating lymphocytes, immune signatures, targeted therapies modulating the immune system, and tumor antigen cancer vaccines. Active immunotherapy in breast cancer and its implementation into clinical trials have been largely a frustrating experience in the last decades. The concept that the immune system regulates cancer development is experiencing a new era of interest. It is clear that the cancer immunosurveillance process indeed exists and potentially acts as an extrinsic tumor suppressor. Also, the immune system can facilitate tumor progression by sculpting the immunogenic phenotype of tumors as they develop. Cancer immunoediting represents a refinement of the cancer immunosurveillance hypothesis and resumes the complex interaction between tumor and immune system into three phases: elimination, equilibrium, and escape. Major topics in the field of immunology deserve a response: what do we know about tumor immunogenicity, and how might we therapeutically improve tumor immunogenicity? How can we modulate response of the immune system? Is there any gene signature predictive of response to immune modulators? The success of future immunotherapy strategies will depend on the identification of additional immunogenic antigens that can serve as the best tumor-rejection targets. Therapeutic success will depend on developing the best antigen delivery systems and on the elucidation of the entire network of immune signaling pathways that regulate immune responses in the tumor microenvironment.

Monitoring tumor-derived cell-free DNA in patients with solid tumors: clinical perspectives and research opportunities.

Circulating cell-free DNA represents a non-invasive biomarker, as it can be isolated from human plasma, serum and other body fluids. Circulating tumor DNA shed from primary and metastatic cancers may allow the non-invasive analysis of the evolution of tumor genomes during treatment and disease progression through 'liquid biopsies'. The serial monitoring of tumor genotypes, which are instable and prone to changes under selection pressure, is becoming increasingly possible. The "liquid biopsy" provide novel biological insights into the process of metastasis and may elucidate signaling pathways involved in cell invasiveness and metastatic competence. This review will focus on the clinical utility of circulating cell free DNA in main solid tumors, including genetic and epigenetic alterations that can be detected.

High Ki-67 score is indicative of a greater benefit from adjuvant chemotherapy when added to endocrine therapy in luminal B HER2 negative and node-positive breast cancer.

BACKGROUND: The indication of adjuvant chemotherapy for patients with highly proliferative estrogen receptor-positive breast cancer is controversial. We analyzed the predictive value of Ki67 for the efficacy of adjuvant chemotherapy in patients with estrogen receptor-positive, node-positive breast cancer. PATIENTS AND METHODS: We identified 1241 patients with Luminal B early stage breast cancer with 1-3 axillary positive nodes who underwent surgery between 1995 and 2005 at the European Institute of Oncology and received adjuvant hormonotherapy and/or chemotherapy. Differences in the distribution of characteristics according to treatment were evaluated by the Chi-square test. To evaluate the effect of adding chemotherapy to hormonotherapy, the propensity score method was used to match patients' characteristics minimizing bias related to the non-random assignment of treatment. RESULTS: The probability of receiving chemotherapy was significantly associated with age, tumor grade, degree of hormone responsiveness, tumor size and peripheral vascular invasion. The propensity score distribution was statistically different between the two treatment groups (p < 0.0001). The 5-year OS percentages were 95.8% (95% CI, 93.5-97.2) in the hormonotherapy group and 96.2% (95%CI, 94.4-97.4%) in the hormonotherapy/chemotherapy group (log-rank test p-value 0.663). The 5-year DFS percentages were 84.6% (95% CI, 81.0-87.6%) in the hormonotherapy group and 84.2% (95% CI, 81.3-86.7%) in the hormonotherapy/chemotherapy group (log-rank test p-value 0.388). However, when analyzing the 5-year DFS by Ki-67 distribution, Subpopulation Treatment Effect Pattern Plot (STEPP) analysis showed a beneficial effect of chemotherapy in patients with highly proliferative tumor (Ki-67 ≥ 32%). The interaction between Ki-67 and treatment was statistically significant (p = 0.027). CONCLUSIONS: Ki67 expression identifies a subset of patients with Luminal B and node-positive breast cancer who could benefit from addition of adjuvant chemotherapy to hormonotherapy. Dichotomy was observed for Ki67 at 32% level.

Developing an effective breast cancer vaccine: challenges to achieving sterile immunity versus resetting equilibrium.

INTRODUCTION: Evading immune destruction is an emerging hallmark of cancer. Immunotherapy of cancer is categorized as either specific stimulation of the immune system by active immunization, with cancer vaccines, or passive transfer of humor or cellular materials, such as, tumor specific antibodies (including immunomodulators) or adoptive cell therapy that inhibit the function of- or directly kill tumor cells. Modulation of immune response in cancer patients is the result of a balanced activity of T regulators and T effector cells. METHODS AND RESULTS: We will present the current information and the prospects for the future of immunotherapy in patients with breast cancer including tumor antigens for vaccines and targets for monoclonal antibodies and adoptive T-cell therapy. DISCUSSION: Active immunotherapy in breast cancer and its implementation into clinical trials has largely been a frustrating experience in the last decades. After many years of controversy, the concept that the immune system regulates cancer development is experiencing a new resurgence. It is clear that the cancer immunosurveillance process indeed exists and potentially acts as an extrinsic tumor suppressor. It has been also clear that the immune system can facilitate tumor progression by sculpting the immunogenic phenotype of tumors as they develop. Cancer immunoediting represents a refinement of the cancer immunosurveillance hypothesis and resumes the complex interaction between tumor and immune system into three phases: elimination, equilibrium, and escape. CONCLUSION: What do we know about tumor immunogenicity and how might we therapeutically improve tumor immunogenicity? The first vaccine and the first immunomodulating agent were recently approved by the US Food and Drug Administration (FDA) for the treatment of prostate cancer (sipuleucel-T) and melanoma (ipilimumab), respectively. The success of future immunotherapy strategies will depend on the identification of additional immunogenic antigens that can serve as the best tumor-rejection targets. Therapeutic success will depend on developing the best antigen delivery systems and on the elucidation of the entire network of immune signalingsignaling pathways that regulate immune responses in the tumor microenvironment.