Immune checkpoint inhibitors: Assessment of the performance and the agreement of iRECIST, irRC, and irRECIST

INTRODUCTION

Immunotherapy has become more widely accepted and used by medical oncologists. Radiologists face challenges in assessing tumor response and becoming more involved in the management of treatment. We aimed to assess the agreement between immune-related response criteria (irRC), immune-related RECIST (irRECIST), and immune RECIST (iRECIST) to correlate the response measured by them with overall survival (OS), and to determine the confirmation rate of progressive disease (PD).

METHODS

A total of 43 patients (28 men, 15 women; average age = 54.6 ± 15.7 years) treated with immunotherapy were included in this study. Pairwise agreements between iRECIST, irRC, and irRECIST were calculated using Cohen's kappa statistics. The correlation of the criteria-based response and OS was evaluated using the Kaplan-Meier method and log-rank test. A confirmation rate with 95% confidence intervals (CI) was calculated in patients with PD.

RESULTS

The kappa values between iRECIST and irRC, iRECIST and irRECIST, and irRC and irRECIST were 0.961 (almost perfect; P < 0.001), 0.961 (almost perfect; P < 0.001), and 0.922 (almost perfect; P < 0.001), respectively. The Kaplan-Meier method and log-rank test showed for each criterion a statistically significant correlation with OS (P < 0.05). The confirmation rates of PD for irRC, irRECIST, and iRECIST were 95% (19/20; 95% CI = 76.4-99.1%), 90% (18/20; 95% CI = 69.9-97.2%), and 90.5% (19/21; 95% CI = 71.1-97.4%), respectively.

CONCLUSION

There was an almost perfect and statistically significant agreement between iRECIST, irRC, and irRECIST. The measurements performed with them significantly correlated with the OS; their confirmation rates were similar. iRECIST and irRECIST might be favored over irRC because of their relative ease of use.

The foundations of immune checkpoint blockade and the ipilimumab approval decennial

Cancer immunity, and the potential for cancer immunotherapy, have been topics of scientific discussion and experimentation for over a hundred years. Several successful cancer immunotherapies - such as IL-2 and interferon-α (IFNα) - have appeared over the past 30 years. However, it is only in the past decade that immunotherapy has made a broad impact on patient survival in multiple high-incidence cancer indications. The emergence of immunotherapy as a new pillar of cancer treatment (adding to surgery, radiation, chemotherapy and targeted therapies) is due to the success of immune checkpoint blockade (ICB) drugs, the first of which - ipilimumab - was approved in 2011. ICB drugs block receptors and ligands involved in pathways that attenuate T cell activation - such as cytotoxic T lymphocyte antigen 4 (CTLA4), programmed cell death 1 (PD1) and its ligand, PDL1 - and prevent, or reverse, acquired peripheral tolerance to tumour antigens. In this Review we mark the tenth anniversary of the approval of ipilimumab and discuss the foundational scientific history of ICB, together with the history of the discovery, development and elucidation of the mechanism of action of the first generation of drugs targeting the CTLA4 and PD1 pathways.

Are radiologists ready to evaluate true response to immunotherapy?

Background

Standardized response criteria for evaluating patients radiological imaging have an essential role in oncological management. Immunotherapy, using immune checkpoint inhibitors (ICIs), including drugs targeting cytotoxic T-lymphocyte-associated antigen 4 and programmed cell death protein 1 or its ligand, promise a new role that has demonstrated improvement management in cancers resistant to chemotherapy. This article reviews the literature to understand the most useful response evaluation criteria for optimal patient management under immunotherapy treatment. Areas that warrant further research are described.

Conclusion

In conclusion, ICIs have become more widely accepted and used by medical oncologists. Radiologists face challenges in assessing tumor response and becoming more involved in the management of treatment. The latest published immune-RECIST criteria can be used in response assessment, but further prospective evaluation is needed with registration clinical trials to be definitively validated.

Challenges in assessing solid tumor responses to immunotherapy

With the advent of immunotherapy as an integral component of multidisciplinary solid tumor treatment, we are confronted by an unfamiliar and novel pattern of radiographic responses to treatment. Enlargement of tumors or even new lesions may not represent progression, but rather reflect what will ultimately evolve into a clinically beneficial response. In addition, the kinetics of radiographic changes in response to immunotherapy treatments may be distinct from what has been observed with cytotoxic chemotherapy and radiation. The phenomenon of pseudoprogression has been documented in patients receiving immunotherapeutic agents, such as checkpoint inhibitors and cellular therapies. Currently, there are no clinical response guidelines that adequately account for pseudoprogression and solid tumor responses to immunotherapy in general. Even so, response criteria have evolved to account for the radiographic manifestations of novel therapies. The evolution of World Health Organization (WHO) criteria and Response Evaluation Criteria in Solid Tumors (RECIST), along with the emergence of immune-related response criteria (irRC) and the immune Response Evaluation Criteria in Solid Tumors (iRECIST) reflect the need for new frameworks. This review evaluates the relationship between pseudoprogression, clinical outcomes, and our current understanding of the biology of pseudoprogression. To achieve our goal, we discuss unusual response patterns in patients receiving immunotherapy. We seek to develop a deeper understanding of radiographic responses to immunotherapy such that clinical benefit is not underappreciated in individual patients and during clinical investigation.

[Tumour assessment criteria for immune checkpoint inhibitors]

The development of immune checkpoint inhibitors in thoracic oncology has led to a reconsideration of the rules for radiological tumor assessment. The RECIST criteria are widely used for the assessment of conventional treatments but are not suitable for anti-tumoral immunotherapy. The mechanism of action of this new class of drugs may induce specific patterns of response, which are not fully assessed by the RECIST criteria. Several new criteria have been proposed to better detect these patterns of response. The changes usually include confirmation of progression, new ways of assessing new lesions, and a larger role for clinical assessment. Nevertheless, harmonization and validation of these criteria remains indispensable. In this review, we will detail the different criteria that are currently available, and discuss their strengths and weaknesses.

[Ipilimumab-induced colitis: A new challenge for gastroenterologists]

Many drugs can produce enterocolitis and they should always be included in the differential diagnosis of this clinical picture. Entities such as antibiotic-associated colitis and neutropenic colitis have been known for some time and recently a new type of drug-induced colitis has emerged due to monoclonal antibodies. Ipimumab is a humanized monoclonal antibody against the CTLA4 molecule that is involved in the maturation and regulation of T lymphocyte activation. This drug causes immune activation and has an immune-mediated antitumor effect with excellent results in tumours such as melanoma. However, several immune-related adverse effects may occur in different organs. The most frequently involved site is the gastrointestinal tract, with adverse effects ranging from mild diarrhoea to colitis with systemic involvement, intestinal perforation, and even death. Although no similarities have been found in the pathogenesis with inflammatory bowel disease, treatments have been used in correlation with its autoimmunological profile: anti-TNF alpha corticosteroids have shown clinical efficacy in moderate to severe disease. However the use of anti-TNF treatment has not been defined and the safety profile is unknown. The inclusion of these new therapies in the treatment of several tumours requires familiarity with these entities and their management should be approached as a new challenge for the gastroenterologist. For that reason, we conducted a review of ipilimumab-induced colitis, evaluating essential features of its symptoms, diagnosis and treatment.

The role of immunotherapy in solid tumors: report from the Campania Society of Oncology Immunotherapy (SCITO) meeting, Naples 2014

The therapeutic approach to advanced or metastatic solid tumors, either with chemotherapy or targeted therapies, is mainly palliative. Resistance to chemotherapy occurs very frequently and is one of the most important reasons for disease progression. Immunotherapy has the potential to mount an ongoing, dynamic immune response that can kill tumor cells for an extended time after the conventional therapy has been administered. Such a long-lasting response is potentially able to completely eradicate tumor cells, rather than producing only a temporary killing of cells. The most promising immune-based treatments are monoclonal antibodies that act as checkpoint inhibitors (e.g. ipilimumab and nivolumab), adoptive cell therapy (e.g. T-cells expressing chimeric antigen receptors) and vaccines (e.g. sipuleucel-T). Ipilimumab is currently approved for the treatment of metastatic melanoma and sipuleucel-T is approved for advanced prostate cancer. There is great interest in immunotherapy in other solid tumors, potentially used alone or in a multimodal fashion with chemotherapy and/or biological drugs. In this paper, we review recent advances in immuno-oncology in solid malignancies (except melanoma) as were discussed at the inaugural meeting of the Campania Society of Oncology Immunotherapy (SCITO).

Comparative clinical benefits of systemic adjuvant therapy for paradigm solid tumors

Adjuvant therapy employing cytotoxic chemotherapy, molecularly targeted agents, immunologic, and hormonal agents has shown a significant impact upon a variety of solid tumors. The principles that guide adjuvant therapy differ among various tumor types and specific modalities, but generally indicate a greater impact of therapy in the postsurgical setting of micrometastatic disease, for which adjuvant therapy is commonly pursued, vs. the setting of gross unresectable disease. This review of adjuvant therapies in current use for five major solid tumors highlights the rationale for current effective adjuvant therapy, and draws comparisons between the adjuvant regimens that have found application in solid tumors.

Antigen-specific versus antigen-nonspecific immunotherapeutic approaches for human melanoma: the need for integration for optimal efficacy?

Due to its immunogenecity and evidence of immune responses resulting in tumor regression, metastatic melanoma has been the target for numerous immunotherapeutic approaches. Unfortunately, based on the clinical outcomes, even the successful induction of tumor-specific responses does not correlate with efficacy. Immunotherapies can be divided into antigen-specific approaches, which seek to induce T cells specific to one or several known tumor associated antigens (TAA), or with antigen-nonspecific approaches, which generally activate T cells to become nonspecifically lytic effectors. Here the authors critically review the different immunotherapeutic approaches in melanoma.

Safety and efficacy of combination immunotherapy with interferon alfa-2b and tremelimumab in patients with stage IV melanoma

PURPOSE

We tested the hypothesis that the combination of tremelimumab and interferon alfa-2b acting via different and possibly synergistic mechanisms would overcome tumor immune tolerance and lead to significant and durable clinical responses.

PATIENTS AND METHODS

We conducted a phase II study in which patients were administered tremelimumab 15 mg/kg/course (three cycles [one cycle = 4 weeks]) intravenously every 12 weeks. High-dose interferon alfa-2b (HDI) was administered concurrently, including intravenous induction at 20 MU/m2/d for 5 d/wk for 4 weeks followed by maintenance at 10 MU/m2/d subcutaneously three times a week for 8 weeks per course. From course 2 onward, HDI maintenance was administered subcutaneously.

RESULTS

Thirty-seven patients with American Joint Committee on Cancer stage IV (9M1a, 6M1b, and 22M1c) were enrolled. Two patients had previously treated brain metastases. Grades 3 and 4 toxicities included neutropenia (six patients; 17%), diarrhea/colitis (four patients; 11%), liver enzyme increase (four patients; 11%), rash (four patients; 11%), fatigue (15 patients; 40%), and anxiety/depression (five patients; 14%). Response data were available for 35 patients. The best objective response rate (RR; Response Evaluation Criteria in Solid Tumors) by intention to treat was 24% (90% CI, 13% to 36%; four complete responses [CRs] and five partial responses [PRs] that lasted 6, 6, > 12, > 14, > 18, 20, > 28, 30, and > 37 months, respectively). Fourteen patients (38%) had stable disease (SD) that lasted 1.5 to 21 months. The median progression-free survival was 6.4 months (95% CI, 3.3 to 12.1 months). The median overall survival (OS) was 21 months (95% CI, 9.5 to not reached). There was a weak association between therapy-induced autoimmunity and clinical benefits (CR/PR/SD; P = .0059), baseline C-reactive protein (CRP) less than or equal to 2.7× the upper limit of normal and clinical benefits (P = .0494) and improved probability of survival (P = .0032), and baseline lymphocyte count of at least 1,000/μL and response (CR/PR; P = .0183) and clinical benefits (CR/PR/SD; P = .0255). Biomarker associations were not significant after adjustment for multiple comparisons.

CONCLUSION

HDI can be administered combined with tremelimumab with acceptable toxicity and promising durable antitumor efficacy that warrant further testing in a randomized trial.

Overcoming immunological tolerance to melanoma: Targeting CTLA-4

Abstract The use of immunotherapeutics in melanoma has received much attention, and recent advances to further characterize the regulatory components of the immune system and the importance of co-stimulatory molecules have opened a new area for clinical investigation. Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) serves as a negative regulator of immunity. Recent trials administering fully human anti-CTLA-4 monoclonal antibodies to melanoma patients have demonstrated clinically meaningful responses. Treatment with CTLA-4 blocking antibodies, however, is not without potential toxicities. Autoimmune side-effects, the most common being colitis-associated diarrhea, are frequently associated with clinical responses. In efforts to build upon prior vaccination efforts as well as attempt to offer patients clinically meaningful immune responses with a CTLA-4 blockade but without significant toxicities, we conducted a clinical trial in patients who previously received autologous tumor cells engineered to secrete granulocyte-macrophage colony stimulating factor (GVAX; Cell Genesys, South San Francisco, CA, USA) with periodic infusions of CTLA-4 blocking antibodies. This sequential treatment resulted in clinically significant anti-tumor immunity without grade 3 or 4 toxicity in most patients. Pathological analyses following treatment of pre-existing tumors revealed a linear correlation between tumor necrosis and the ratio of intra-tumoral CD8+ effector cells to FoxP3+ regulatory cells (T(regs)). Effective anti-tumor immunity and serious autoimmunity can be disassociated. Further targeting of anti-tumor T(regs)in combinatorial therapy approaches may be a rich avenue of future investigation.

Novel immunotherapies as potential therapeutic partners for traditional or targeted agents: cytotoxic T-lymphocyte antigen-4 blockade in advanced melanoma

The successful management of advanced melanoma remains an unmet need because of a resolutely poor prognosis and therapeutic options with limited effectiveness. Dacarbazine and fotemustine are the only approved chemotherapeutic agents for advanced melanoma, yet neither alone or in combination regimens has been shown to extend survival in randomized clinical trials. The only agent to be approved for advanced melanoma in the US in more than 30 years is high-dose bolus interleukin-2, but its use is associated with high toxicity and cost, and it has also failed to show a survival benefit. Our expanding knowledge of the complex factors and pathways regulating immune function has led to the advent of novel immunotherapeutic agents. Among these are ipilimumab and tremelimumab - fully human, monoclonal antibodies directed against cytotoxic T-lymphocyte antigen-4 (CTLA-4). The pivotal role of CTLA-4 in regulating T-cell function is established, and a series of preclinical studies provided proof-of-concept evidence of the antitumor activity of anti-CLTA-4 antibodies in combination with vaccines or chemotherapy. Subsequently, anti-CTLA-4 antibodies have shown encouraging results in clinical trials in advanced melanoma. Recent progress in the understanding of melanoma genetics and tumorigenesis has led to potential new therapeutic targets. Molecular targeted agents that inhibit the proliferation and survival of metastatic melanoma cells offer potential partners for anti-CTLA-4 antibodies in combined modality regimens. Novel combinations are reviewed in the context of creating an immunosupportive environment in the host.

Single-institution experience with ipilimumab in advanced melanoma patients in the compassionate use setting: lymphocyte count after 2 doses correlates with survival

BACKGROUND

Ipilimumab is a monoclonal antibody that antagonizes cytotoxic T lymphocyte antigen-4, a negative regulator of the immune system. The authors report on advanced refractory melanoma patients treated in a compassionate use trial of ipilimumab at the Memorial Sloan-Kettering Cancer Center.

METHODS

Patients with advanced refractory melanoma were treated in a compassionate use trial with ipilimumab 10 mg/kg every 3 weeks for 4 doses. Those with evidence of clinical benefit at Week 24 (complete response [CR], partial response [PR], or stable disease [SD]) then received ipilimumab every 12 weeks.

RESULTS

A total of 53 patients were enrolled, with 51 evaluable. Grade 3/4 immune-related adverse events were noted in 29% of patients, with the most common immune-related adverse events being pruritus (43%), rash (37%), and diarrhea (33%). On the basis of immune-related response criteria, the response rate (CR + PR) was 12% (95% confidence interval [CI], 5%-25%), whereas 29% had SD (95% CI, 18%-44%). The median progression-free survival was 2.6 months (95% CI, 2.3-5.2 months), whereas the median overall survival (OS) was 7.2 months (95% CI, 4.0-13.3 months). Patients with an absolute lymphocyte count (ALC) ≥1000/μL after 2 ipilimumab treatments (Week 7) had a significantly improved clinical benefit rate (51% vs 0%; P = .01) and median OS (11.9 vs 1.4 months; P < .001) compared with those with an ALC <1000/μL.

CONCLUSIONS

The results confirm that ipilimumab is clinically active in patients with advanced refractory melanoma. The ALC after 2 ipilimumab treatments appears to correlate with clinical benefit and OS, and should be prospectively validated. Cancer 2010. © 2010 American Cancer Society.

This description of 51 patients with advanced, treatment-refractory melanoma who were enrolled in a compassionate use trial of ipilimumab at Memorial Sloan-Kettering Cancer Center confirms that ipilimumab is active in this disease setting. In addition, the results suggest that the absolute lymphocyte count after 2 ipilimumab treatments (at Week 7) highly correlates with the rate of clinical benefit at Week 24 and overall survival.

Large randomized study of thymosin alpha 1, interferon alfa, or both in combination with dacarbazine in patients with metastatic melanoma

PURPOSE

Thymosin alpha 1 (Talpha1) is an immunomodulatory polypeptide that enhances effector T-cell responses. In this large randomized study, we evaluated the efficacy and safety of combining Talpha1 with dacarbazine (DTIC) and interferon alfa (IFN-alpha) in patients with metastatic melanoma.

PATIENTS AND METHODS

Four hundred eighty-eight patients were randomly assigned to five treatment groups: DTIC+IFN-alpha+Talpha1 (1.6 mg); DTIC+IFN-alpha+Talpha1 (3.2 mg); DTIC+IFN-alpha+Talpha1 (6.4 mg); DTIC+Talpha1 (3.2 mg); DTIC+IFN-alpha (control group). The primary end point was best overall response at study end (12 months). Secondary end points included duration of response, overall survival (OS), and progression-free survival (PFS). Patients were observed for up to 24 months.

RESULTS

Ten and 12 tumor responses were observed in the DTIC+IFN-alpha+Talpha1 (3.2 mg) and DTIC+Talpha1 (3.2 mg) groups, respectively, versus four in the control group, which was sufficient to reject the null hypothesis that P(0) < or = .05 (expected response rate of standard therapy) in these two arms. Duration of response ranged from 1.9 to 23.2 months in patients given Talpha1 and from 4.4 to 8.4 months in the control group. Median OS was 9.4 months in patients given Talpha1 versus 6.6 months in the control group (hazard ratio = 0.80; 9% CI, 0.63 to 1.02; P = .08). An increase in PFS was observed in patients given Talpha1 versus the control group (hazard ratio = 0.80; 95% CI, 0.63 to 1.01; P = .06). Addition of Talpha1 to DTIC and IFN-alpha did not lead to any additional toxicity.

CONCLUSION

These results suggest Talpha1 has activity in patients with metastatic melanoma and provide rationale for further clinical evaluation of this agent.

Guidelines for the evaluation of immune therapy activity in solid tumors: immune-related response criteria

PURPOSE

Immunotherapeutic agents produce antitumor effects by inducing cancer-specific immune responses or by modifying native immune processes. Resulting clinical response patterns extend beyond those of cytotoxic agents and can manifest after an initial increase in tumor burden or the appearance of new lesions (progressive disease). Response Evaluation Criteria in Solid Tumors or WHO criteria, designed to detect early effects of cytotoxic agents, may not provide a complete assessment of immunotherapeutic agents. Novel criteria for the evaluation of antitumor responses with immunotherapeutic agents are required.

EXPERIMENTAL DESIGN

The phase II clinical trial program with ipilimumab, an antibody that blocks CTL antigen-4, represents the most comprehensive data set available to date for an immunotherapeutic agent. Novel immune therapy response criteria proposed, based on the shared experience from community workshops and several investigators, were evaluated using data from ipilimumab phase II clinical trials in patients with advanced melanoma.

RESULTS

Ipilimumab monotherapy resulted in four distinct response patterns: (a) shrinkage in baseline lesions, without new lesions; (b) durable stable disease (in some patients followed by a slow, steady decline in total tumor burden); (c) response after an increase in total tumor burden; and (d) response in the presence of new lesions. All patterns were associated with favorable survival.

CONCLUSION

Systematic criteria, designated immune-related response criteria, were defined in an attempt to capture additional response patterns observed with immune therapy in advanced melanoma beyond those described by Response Evaluation Criteria in Solid Tumors or WHO criteria. Further prospective evaluations of the immune-related response criteria, particularly their association with overall survival, are warranted.

Phase I study of ipilimumab, an anti-CTLA-4 monoclonal antibody, in patients with relapsed and refractory B-cell non-Hodgkin lymphoma

PURPOSE

The growth of non-Hodgkin lymphomas can be influenced by tumor-immune system interactions. Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a negative regulator of T-cell activation that serves to dampen antitumor immune responses. Blocking anti-CTLA-4 monoclonal antibodies improves host resistance to immunogenic tumors, and the anti-CTLA-4 antibody ipilimumab (MDX-010) has clinical activity against melanoma, prostate, and ovarian cancers.

EXPERIMENTAL DESIGN

We did a phase I trial of ipilimumab in patients with relapsed/refractory B-cell lymphoma to evaluate safety, immunologic activity, and potential clinical efficacy. Treatment consisted of ipilimumab at 3 mg/kg and then monthly at 1 mg/kg x 3 months (dose level 1), with subsequent escalation to 3 mg/kg monthly x 4 months (dose level 2).

RESULTS

Eighteen patients were treated, 12 at the lower dose level and 6 at the higher dose level. Ipilimumab was generally well tolerated, with common adverse events attributed to it, including diarrhea, headache, abdominal pain, anorexia, fatigue, neutropenia, and thrombocytopenia. Two patients had clinical responses; one patient with diffuse large B-cell lymphoma had an ongoing complete response (>31 months), and one with follicular lymphoma had a partial response lasting 19 months. In 5 of 16 cases tested (31%), T-cell proliferation to recall antigens was significantly increased (>2-fold) after ipilimumab therapy.

CONCLUSIONS

Blockade of CTLA-4 signaling with the use of ipilimumab is well tolerated at the doses used and has antitumor activity in patients with B-cell lymphoma. Further evaluation of ipilimumab alone or in combination with other agents in B-cell lymphoma patients is therefore warranted.

Immunotherapy of distant metastatic disease

Immunotherapy of metastatic melanoma consists of various approaches leading to specific or non-specific immunomodulation. The use of FDA-approved interleukin (IL)-2 alone, in combination with interferon alpha, and/or with various chemotherapeutic agents (biochemotherapy) is associated with significant toxicity and poor efficacy that does not improve overall survival of 96% of patients. Many studies with allogeneic and autologous vaccines have demonstrated no clinical benefit, and some randomised trials even showed a detrimental effect in the vaccine arm. The ongoing effort to develop melanoma vaccines based on dendritic cells and peptides is driven by advances in understanding antigen presentation and processing, and by new techniques of vaccine preparation, stabilisation and delivery. Several agents that have shown promising activity in metastatic melanoma including IL-21 and monoclonal antibodies targeting cytotoxic T lymphocyte-associated antigen 4 (anti-CTLA-4) or CD137 are discussed. Recent advances of intratumour gene transfer technologies and adoptive immunotherapy, which represents a promising although technically challenging direction, are also discussed.

Melanoma in pediatric, adolescent, and young adult patients

The family practitioner, pediatrician, and dermatologist all have potential roles in the primary prevention, diagnosis, and treatment of localized thin melanomas. Surgical and medical oncologists are often involved when controversy arises over the nature of the skin lesion or whether sentinel lymph node (SLN) biopsies and adjuvant therapy are to be contemplated. This overview of melanoma will deal with the primary and nodal pathology, surgery, and medical therapy of melanoma in pediatric, adolescent, and young adult patients--and will raise areas of controversy that are only recently being addressed in databases of cases from this age group.

A randomized, double-blind, placebo-controlled, phase II study comparing the tolerability and efficacy of ipilimumab administered with or without prophylactic budesonide in patients with unresectable stage III or IV melanoma

PURPOSE

Diarrhea (with or without colitis) is an immune-related adverse event (irAE) associated with ipilimumab. A randomized, double-blind, placebo-controlled, multicenter, multinational phase II trial was conducted to determine whether prophylactic budesonide (Entocort EC), a nonabsorbed oral steroid, reduced the rate of grade >or=2 diarrhea in ipilimumab-treated patients with advanced melanoma.

EXPERIMENTAL DESIGN

Previously treated and treatment-naïve patients (N = 115) with unresectable stage III or IV melanoma received open-label ipilimumab (10 mg/kg every 3 weeks for four doses) with daily blinded budesonide (group A) or placebo (group B) through week 16. The first scheduled tumor evaluation was at week 12; eligible patients received maintenance treatment starting at week 24. Diarrhea was assessed using Common Terminology Criteria for Adverse Events (CTCAE) 3.0. Patients kept a diary describing their bowel habits.

RESULTS

Budesonide did not affect the rate of grade >or=2 diarrhea, which occurred in 32.7% and 35.0% of patients in groups A and B, respectively. There were no bowel perforations or treatment-related deaths. Best overall response rates were 12.1% in group A and 15.8% in group B, with a median overall survival of 17.7 and 19.3 months, respectively. Within each group, the disease control rate was higher in patients with grade 3 to 4 irAEs than in patients with grade 0 to 2 irAEs, although many patients with grade 1 to 2 irAEs experienced clinical benefit. Novel patterns of response to ipilimumab were observed.

CONCLUSIONS

Ipilimumab shows activity in advanced melanoma, with encouraging survival and manageable adverse events. Budesonide should not be used prophylactically for grade >or=2 diarrhea associated with ipilimumab therapy.

The monoclonal antibody to cytotoxic T lymphocyte antigen 4, ipilimumab (MDX-010), a novel treatment strategy in cancer management

BACKGROUND

Cytotoxic T lymphocyte antigen 4 (CTLA-4) is an inhibitory regulator of the T cell immune response against tumor cells. Ipilimumab (MDX-010) is a monoclonal antibody directed against CTLA-4.

OBJECTIVE

To describe the basic mechanism of ipilimumab and discuss data available to date with regards to its safety and efficacy profile.

METHODS

Data from clinical trials including abstracts were reviewed using the PubMed Database as well as the American Society of Clinical Oncology Abstract Database.

CONCLUSIONS

CTLA-4 inhibition with a monoclonal antibody is usually well tolerated and has efficacy as a therapeutic agent in a variety of cancers. The most clinically important toxicities have been related to autoimmune events, and guidelines for treatment of these effects are now available. Preliminary results indicate that therapy with ipilimumab leads to durable responses. Pharmacokinetics and pharmacodynamics are different from those of traditional chemotherapy agents. Phase III studies are currently underway for melanoma.

Costimulatory and coinhibitory receptors in anti-tumor immunity

SUMMARY

Despite the expression of antigens by tumor cells, spontaneous immune-mediated rejection of cancer seems to be a rare event. T-cell receptor engagement by peptide/major histocompatibility complexes constitutes the main signal for the activation of naive T cells but is not sufficient to initiate a productive generation and maintenance of effector cells. Full activation of T cells requires additional signals driven by costimulatory molecules present on activated antigen-presenting cells but rarely on tumors. Following the discovery of B7-1 (CD80), several other costimulatory molecules have been shown to contribute to T-cell activation and have relevance for improving anti-tumor immunity. Moreover, increasing the understanding of coinhibitory receptors has highlighted key additional pathways that can dominantly inhibit anti-tumor T-cell function. Improving positive costimulation, and interfering with negative regulation, continues to represent an attractive immunotherapeutic approach for the treatment of cancer. This review focuses upon those pathways with the highest potential for clinical application in human cancer patients.

Ipilimumab: controversies in its development, utility and autoimmune adverse events

A promising new class of anti-cancer drugs includes antibodies that mediate immune regulatory effects. It has become very clear over the last decade that different types of immune cells and different pathways serve to suppress anti-cancer immunity, particularly in the microenvironment of the tumor. The first examples of immune modulating antibodies are those directed against cytotoxic T lymphocyte antigen-4 (CTLA-4), a molecule present on activated T cells. Human antibodies that abrogate the function of CTLA-4 have been tested in the clinic and found to have clinical activity against melanoma. In this review, we discuss some of the controversies surrounding the potential clinical utility of one of those antibodies, ipilimumab, formerly MDX-010, from Medarex and Bristol Myers Squibb. The optimal dose and schedule of ipilimumab was derived in multiple clinical trials whose latest results are described below. Favorable survival in patients with stage IV melanoma were observed that appear to be associated with unique side effects of the drug called "immune-related adverse events". The management of these side effects is described, and the unusual kinetics of anti-tumor response with ipilimumab as well as a newly proposed schema for assessing anti-tumor responses in patients receiving biologic compounds like ipilimumab, which may supercede RECIST or WHO criteria, are addressed.

Overcoming immunologic tolerance to melanoma: targeting CTLA-4 with ipilimumab (MDX-010)

Targeted biologic therapies such as anti-cytotoxic T lymphocyte antigen (CTLA-4) monoclonal antibodies, either as monotherapy or in combination with chemotherapy or vaccines, have shown great promise in late-stage melanoma, which has a very poor prognosis. Melanoma is relatively resistant to both chemotherapy and radiotherapy. Blockade of CTLA-4, which inhibits T-cell proliferation, promotes stimulation of adaptive immunity and T-cell activation, resulting in eradication of tumor cells. Two human monoclonal antibodies are under investigation in melanoma. Phase II and III clinical trials are currently evaluating the efficacy and safety of ipilimumab (MDX-010, Medarex, Inc., Princeton, NJ, and Bristol-Myers Squibb, Princeton, NJ) and tremelimumab (CP-675,206; Pfizer Pharmaceuticals, New York) in melanoma. Data are available on ipilimumab, which has been explored as monotherapy and in combination with vaccines, other immunotherapies such as interleukin-2, and chemotherapies such as dacarbazine. Overall response rates range from 13% with ipilimumab plus vaccine in patients with stage IV disease to 17% and 22% with ipilimumab plus dacarbazine or interleukin-2, respectively, in patients with metastatic disease. Responses have been durable, and among those experiencing grade 3 or 4 autoimmune toxicities, even higher response rates have been seen--up to 36%. While the optimal dose of ipilimumab has yet to be established, studies also indicate that higher doses may be more effective. Importantly, the lack of an initial clinical response may not predict ultimate treatment failure, because the onset of a response may follow progressive disease or stable disease. Pending results from registration studies with ipilimumab and lessons learned from registration studies conducted with tremelimumab will help to define the role of anti-CTLA-4 blockade in the treatment of metastatic melanoma.

Anti-cytotoxic T-lymphocyte antigen-4 antibody: the first in an emerging class of immunomodulatory antibodies for cancer treatment

PURPOSE

To evaluate the emerging role of immunomodulatory antibodies in cancer treatment. Antibodies (ipilimumab and tremelimumab) targeting cytotoxic T-lymphocyte antigen-4 (CTLA-4), an inhibitory molecule on T cells, represent the vanguard of these new drugs.

DESIGN

We performed a systematic review of the clinical studies examining the clinical activity of anti-CTLA-4 antibodies. We also review the potential mechanisms and toxicities associated with these treatments.

RESULTS

Clinical activity with anti-CTLA-4 monoclonal antibodies (mAbs) has paved the way for additional T-cell immunomodulatory monoclonal antibody (mAb) approaches for the treatment of cancer to be investigated. Because anti-CTLA-4 mAbs target the immune system and not the tumor, they may provide significant potential advantages over traditional antitumor mAbs, chemotherapies, and immunotherapies (ie, vaccines and cytokines). Other antibodies, such as CD137 agonists, CD40 agonists, and PD-1 antagonists, are currently in various stages of preclinical and clinical development.

CONCLUSION

Available clinical data suggest that anti-CTLA-4 mAbs are very different from traditional mAbs, chemotherapies, and immunotherapies in terms of patterns of response, duration of response, and adverse event profile. Ongoing clinical studies aim to establish the efficacy and safety of anti-CTLA-4 mAbs as monotherapy or in combination with other drugs for the treatment of metastatic melanoma and a variety of other cancer types.