Anti-cytotoxic T-lymphocyte Antigen-4 Antibody Research Articles

Re-immunotherapy with nivolumab plus ipilimumab in advanced non-small cell lung cancer patients previously treated with anti-programmed death-1 and/or anti-programmed death ligand-1 antibodies

BackgroundThe role of re-immunotherapy in advanced non-small cell lung cancer (NSCLC) remains unclear. No studies have evaluated the re-immunotherapy regimen including anti-cytotoxic T-lymphocyte antigen-4 antibody for lung cancer treatment. This study aimed to investigate the efficacy and safety of re-immunotherapy with nivolumab plus ipilimumab in patients with advanced NSCLC previously treated with anti-programmed death-1 (PD-1) and/or anti-programmed death ligand-1 (PD-L1) antibodies.MethodsWe retrospectively reviewed patients with advanced or recurrent NSCLC who received immunotherapy with nivolumab plus ipilimumab (without concomitant cytotoxic chemotherapy) between November 2020 and November 2022 at the National Hospital Organization Kyoto Medical Center, Kyoto, Japan. Data were extracted from patients who had previously received immunotherapies with anti-PD-1 and/or anti-PD-L1 antibodies. Treatment responses and adverse events were evaluated.ResultsOf the 67 patients who received immunotherapy with nivolumab plus ipilimumab, 23 were included in final analysis. The objective response rate was 17%, and the disease control rate was 48% for nivolumab plus ipilimumab therapy. The highest grade of immune-related adverse events was grade 3, occurring in 11% of cases.ConclusionRe-immunotherapy with nivolumab plus ipilimumab after anti-PD-1 and/or anti-PD-L1 immunotherapy may be feasible and provide clinical benefit in selected patients. Further prospective studies are warranted to identify the patient population that may benefit from re-immunotherapy.

Increased Risk of Thyroid Dysfunction by PD-1 and CTLA-4 Blockade in Patients Without Thyroid Autoantibodies at Baseline.

Previous studies showed that although the risk of thyroid dysfunction [thyroid immune-related adverse events (irAEs)] induced by anti-programmed cell death-1 antibodies (PD-1-Ab) was as low as 2% to 7% in patients negative for anti-thyroid antibodies (ATAs) at baseline, it was much higher (30%-50%) in patients positive for ATAs. However, whether a similar increase occurs with combination therapy using PD-1-Ab plus anti-cytotoxic T-lymphocyte antigen-4 antibody (CTLA-4-Ab) is unknown. A total of 451 patients with malignancies treated with PD-1-Ab, CTLA-4-Ab, or a combination of PD-1-Ab and CTLA-4-Ab (PD-1/CTLA-4-Abs) were evaluated for ATAs at baseline and for thyroid function every 6 weeks for 24 weeks after treatment initiation and then observed until the last clinical visit. Of the 451 patients, 51 developed thyroid irAEs after immunotherapy [41 of 416 (9.9%) treated with PD-1-Ab, 0 of 8 (0%) treated with CTLA-4-Ab, and 10 of 27 (37.0%) treated with PD-1/CTLA-4-Abs]. The cumulative incidence of thyroid irAEs was significantly higher in patients who were positive vs negative for ATAs at baseline after both PD-1-Ab [28/87 (32.2%) vs 13/329 (4.0%), P < 0.001] and PD-1/CTLA-4-Abs [6/10 (60.0%) vs 4/17 (23.5%), P < 0.05] treatments. The risk of thyroid irAEs induced by PD-1/CTLA-4Abs, which was significantly higher than that induced by PD-1-Ab, in patients negative for ATAs at baseline was not statistically different from that induced by PD-1-Ab in patients positive for ATAs at baseline. This study showed that the incidence of thyroid irAEs was high and not negligible after PD-1/CTLA-4-Abs treatment even in patients negative for ATAs at baseline.

Acute neurological adverse events during immune checkpoint inhibition therapy in patients with melanoma brain metastases.

The common adverse effects of immune checkpoint blockade therapy are well recognised. However, neurological adverse effects of checkpoint inhibitor therapy are less widely appreciated, and their clinical management remains challenging. Therefore, we report our experience of managing acute, life-threatening neurological toxicity during immune checkpoint inhibitor therapy. Five male patients with stage IV melanoma underwent anti-programmed cell death protein 1 therapy (monotherapy or combination therapy with anti-cytotoxic T-lymphocyte antigen-4 antibodies) and developed severe neurological symptoms and signs including headache, hemiparesis and dysarthria. The initial diagnosis of brain metastases actually occurred after initiation of checkpoint inhibitor therapy in three of the patients, whereas two patients had pre-existing central nervous metastases and developed cerebral oedema and haemorrhage during immunotherapy. A rapidly fatal outcome occurred in two patients treated with immunotherapy following the development of BRAF-inhibitor and MEK-inhibitor resistance. Four of the patients died owing to neurological complications, and one achieved a complete cerebral response. Immunotherapy and tumour progression can both result in the development of neurological symptoms and signs, making it difficult to determine causality. However, the temporal relationship between the development of neurological symptoms and the first administration of therapy means that patients should be closely monitored for the development of neurological sequelae, which may even herald the presence of occult brain metastases. The decision on whether to continue immunotherapy must balance the risks of symptom - versus disease progression. However, in our case series, it is encouraging to note that the initial acute neurological symptoms were often transient. Nevertheless, pretherapeutic brain imaging to exclude occult brain metastases and stratify the risk of intracerebral oedema and haemorrhage should be considered.

Increased frequency of acute reactions to iodinated contrast media in cancer patients treated with anti-CTLA-4 immunomodulatory antibodies

Contrast-enhanced computed tomography (CECT) is an indispensable tool in the management of cancer patients. However, this procedure can be complicated by the development of acute adverse reactions (ARs) to iodinated contrast media (ICM). On the basis of the hypothesis that cancer immunotherapy, in particular with immune checkpoint inhibitors, increases the incidence of allergic-like immediate ARs to ICM with respect to “standard” cancer chemotherapy/targeted therapy (CHT) we retrospectively evaluated the incidence of CECT-related immediate ARs in cancer patients undergoing cancer treatments. All patients who underwent at least one CECT scan after starting any cancer treatment between 2006 and 2014 were included in a mono-institutional radiological database. The staff of the Radiology Unit recorded any ARs that occurred within 30 min of the ICM injection and classified them as “allergic-like” or “physiologic” and graded as mild, moderate, or severe according to the American College of Radiology (ACR) Manual on Contrast Media, version 10.1. Fifty-nine of the 3,521 patients included in the database received ipilimumab (Ipi), 75 received cytokines (Cys), and the remaining 3,387 received non-immunologic agents (CHT). Overall, 71 (2%) patients suffered ICM-related ARs. The incidence of ICM-related ARs was higher in Ipi- and Cy-treated patients than in those who received CHT (12%, 5%, and 2%, respectively). Our data show that immunological cancer treatments, particularly Ipi, considerably increase the proportion of patients suffering CECT-related immediate ARs with respect to non-immunologic agents. Although these findings need to be validated in larger prospective studies, they serve as a “wake-up call” for radiologists to closely monitor patients who have previously received cancer immunotherapy with anti-cytotoxic T-lymphocyte antigen-4 antibodies when using ICM in order to reduce the risk of potentially severe immediate ARs.

Regulatory T cell-targeted hybrid nanoparticles combined with immuno-checkpoint blockage for cancer immunotherapy

Immunosuppression in tumor microenvironments induced by regulatory T (Treg) cells is regarded a critical mechanism of tumor immune escape and poses a major impediment to cancer immunotherapy. In this study, we developed tLyp1 peptide-conjugated hybrid nanoparticles for targeting Treg cells in the tumor microenvironment. The tLyp1 peptide-modified hybrid nanoparticles presented good stability and effective targeting to Treg cells, and they enhanced the effect of imatinib in downregulating Treg cell suppression through inhibition of STAT3 and STAT5 phosphorylation. In addition, an in vivo study revealed high tumor accumulation of the hybrid nanoparticle. Specifically, prolonged survival rate, enhanced tumor inhibition, reduced intratumoral Treg cells, and elevated intratumoral CD8+ T cells against tumor were observed when combined with checkpoint-blockade by using anti-cytotoxic T-lymphocyte antigen-4 antibody. This study provided groundwork for a repertoire of nanoparticle-based drugs for targeting and modulating Treg cell function in the tumor microenvironment and for improving antitumor immunotherapy.

Clinical Pharmacology Considerations for the Development of Immune Checkpoint Inhibitors.

Immuno-oncology works through activation of the patient's immune system against cancer, with several advantages over other treatment approaches, including cytotoxic agents and molecular-targeted therapies. The most notable feature of immuno-oncology treatments is the nature of the patient responses achieved, which can be more durable and sustained than with other modalities. Increased understanding of immune system complexity has provided a number of opportunities to advance several strategies for the development of immuno-oncology therapies. This review outlines the clinical pharmacology characteristics and development challenges for the 6 approved immunomodulatory monoclonal antibodies that target 2 immune checkpoint pathways: ipilimumab (an anti-cytotoxic T-lymphocyte antigen-4 antibody) and, more recently, nivolumab and pembrolizumab (both anti-programmed death-1 antibodies) and atezolizumab, avelumab, and durvalumab (all anti-programmed death ligand-1 antibodies). These agents have revealed much about the clinical pharmacology features of immune checkpoint inhibitors as a class, as well as the pharmacometric approaches used to support their clinical development and regulatory approval. The development experiences with these pioneering immuno-oncology agents are likely to serve as useful guides in the discovery, progression, and approval of future drugs or combination of drugs in this class. This review includes summaries of the pharmacokinetics and exposure-response of the immune checkpoint inhibitors approved to date, as well as an overview of some quantitative systems pharmacology approaches. The ability of immuno-oncology to meet its full potential will depend on overcoming development challenges, including the need for clear strategies to determine optimal dose and scheduling for monotherapy as well as combination approaches.

P14.08 Neurological complications of emerging targeted therapies

AbstractIntroduction:The development of new biological and immunotherapeutic agents to treat cancer associates unknown neurological toxicities. Crizotinib (Cri), an anaplastic lymphoma kinase and c-ros oncogene 1 hepatocyte growth factor receptor tyrosine-kinase inhibitor, has been approved for the treatment of advanced ALK-positive non-small cell lung cancer. Ipilimumab (Ipi), an anticytotoxic T-lymphocyte antigen-4 antibody, was the first agent to demonstrate improved survival in patients with metastatic melanoma. This report describes a patient treated with Ipi showing a not previously reported neurological adverse event; and a patient treated with Cri showing atypical brain metastases.Patients and methods:Patient 1(P1): 66-year-old male with a history of irresectable nasal melanoma, started on Ipi plus concomitant radiotherapy on September/2015, obtaining a radiological partial response. Two months later he developed progressive cognitive impairment, urinary incontinence and gait difficulties. A neuroaxis MRI revealed multiple acute and subacute subcentimeter ischemic lesions with contrast enhancement and restricted diffusion with diffuse FLAIR signal changes. CSF reported protein elevation, normal glucose and mild lymphocytic pleocytosis without neoplastic cells. Microbiological cultures and PCRs were negative. Echocardiography was normal. Patient 2(P2): 54-year-old non-smoker female with lung adenocarcinoma (EGFR wild-type and ALK translocation) and spinal metastatic disease at diagnosis, started on Cri after failure of first-line treatment with cisplatin plus pemetrexed. After 16 cycles, an increase in carcinoembryonic antigen was noted without progression of ganglio-pulmonary disease. Although asymptomatic, CNS progression was suspected and follow-up brain MRI reported multiple bilateral supra and infratentorial large cystic lesions with perilesional edema and no contrast enhancement.Results:P1: primary angiitis of the CNS was suspected, although arteriography was unremarkable. He received high-dose metilprednisolone followed by cyclophosphamide bolus. The inflammatory component of CSF and neurological symptoms presented partial improvement but brain MRI showed a dissociate response. P2: PET scan revealed irregular distribution of the radiotracer and hypometabolic lesions. Follow-up brain MRI revealed stabilization with a perfusion-weighted sequence reporting an increase in the relative cerebral blood volume of the bigger cystic lesion. These features led us to the diagnostic of indolent brain metastases.Conclusions:Early recognition of new neurological patterns of toxicity may lead to drug discontinuation or dose adjustment preventing further neurological deterioration. A better knowledge of these toxicities will help differentiate treatment-related complications from metastatic progression.

Managing Cutaneous Side Effects From Targeted Molecular Inhibitors for Melanoma and Nonmelanoma Skin Cancer.

Targeted anticancer therapies can cause cutaneous adverse events different from classical chemotherapeutic toxicities. To review the literature on dermatologic adverse events (DAEs) of targeted molecular inhibitors for melanoma and nonmelanoma skin cancers with a focus on management options. A comprehensive literature search related to the side effects and management of these side effects from vemurafenib, dabrafenib, trametinib (BRAF inhibitors), pembrolizumab (antiprogrammed-death-receptor-1 antibody), imatinib (tyrosine kinase inhibitor), ipilimumab (anticytotoxic T-lymphocyte antigen-4 antibody), cetuximab (epidermal growth factor receptor inhibitor), sorafenib (multikinase inhibitor), and vismodegib (smoothened receptor inhibitor). No large controlled studies specifically examining the management of DAEs of targeted molecular inhibitors exist, although there are case report-based recommendations and algorithms developed by expert panels to manage these adverse events. Many options for managing the cutaneous side effects of targeted molecular inhibitors are similar to those used in general dermatology practice. When used effectively, drug dosing and patient quality of life may be optimized.

Programmed death-1 & its ligands: promising targets for cancer immunotherapy.

Novel strategies for cancer treatment involving blockade of immune inhibitors have shown significant progress toward understanding the molecular mechanism of tumor immune evasion. The preclinical findings and clinical responses associated with programmed death-1 (PD-1) and PD-ligand pathway blockade seem promising, making these targets highly sought for cancer immunotherapy. In fact, the anti-PD-1 antibodies, pembrolizumab and nivolumab, were recently approved by the US FDA for the treatment of unresectable and metastatic melanoma resistant to anticytotoxic T-lymphocyte antigen-4 antibody (ipilimumab) and BRAF inhibitor. Here, we discuss strategies of combining PD-1/PD-ligand interaction inhibitors with other immune checkpoint modulators and standard-of-care therapy to break immune tolerance and induce a potent antitumor activity, which is currently a research area of key scientific pursuit.

Genetic Basis for Clinical Response to CTLA-4 Blockade in Melanoma

BackgroundImmune checkpoint inhibitors are effective cancer treatments, but molecular determinants of clinical benefit are unknown. Ipilimumab and tremelimumab are antibodies against cytotoxic T-lymphocyte antigen 4 (CTLA-4). Anti–CTLA-4 treatment prolongs overall survival in patients with melanoma. CTLA-4 blockade activates T cells and enables them to destroy tumor cells.MethodsWe obtained tumor tissue from patients with melanoma who were treated with ipilimumab or tremelimumab. Whole-exome sequencing was performed on tumors and matched blood samples. Somatic mutations and candidate neoantigens generated from these mutations were characterized. Neoantigen peptides were tested for the ability to activate lymphocytes from ipilimumab-treated patients.ResultsMalignant melanoma exomes from 64 patients treated with CTLA-4 blockade were characterized with the use of massively parallel sequencing. A discovery set consisted of 11 patients who derived a long-term clinical benefit and 14 patients who derived a minimal benefit or no benefit. Mutational load was associated with the degree of clinical benefit (P=0.01) but alone was not sufficient to predict benefit. Using genomewide somatic neoepitope analysis and patient-specific HLA typing, we identified candidate tumor neoantigens for each patient. We elucidated a neoantigen landscape that is specifically present in tumors with a strong response to CTLA-4 blockade. We validated this signature in a second set of 39 patients with melanoma who were treated with anti–CTLA-4 antibodies. Predicted neoantigens activated T cells from the patients treated with ipilimumab.ConclusionsThese findings define a genetic basis for benefit from CTLA-4 blockade in melanoma and provide a rationale for examining exomes of patients for whom anti–CTLA-4 agents are being considered. (Funded by the Frederick Adler Fund and others.)

New Strategies in Lung Cancer: Translating Immunotherapy into Clinical Practice

Recent breakthroughs in translating the early development of immunomodulatory antibodies into the clinic, notably with the anti-cytotoxic T-lymphocyte antigen-4 antibody, ipilimumab, have led to durable benefits and prolonged survival for a subgroup of patients with advanced melanoma. Subsequent studies have shown that related immune checkpoint antibodies, specifically those targeting the programmed death-1 pathway, have activity in non-small cell lung cancer. Non-small cell lung cancer is the commonest cause of cancer death worldwide and this exciting avenue of clinical investigation carries with it great promise and new challenges. In this article, we discuss recent developments in lung cancer immunotherapy, reviewing recent findings from therapeutic vaccine studies and in particular we focus on the refinement of immunomodulation as a therapeutic strategy in this challenging disease.

Indoleamine 2,3-dioxygenase is a critical resistance mechanism in antitumor T cell immunotherapy targeting CTLA-4

The cytotoxic T lymphocyte antigen-4 (CTLA-4)-blocking antibody ipilimumab results in durable responses in metastatic melanoma, though therapeutic benefit has been limited to a fraction of patients. This calls for identification of resistance mechanisms and development of combinatorial strategies. Here, we examine the inhibitory role of indoleamine 2,3-dioxygenase (IDO) on the antitumor efficacy of CTLA-4 blockade. In IDO knockout mice treated with anti-CTLA-4 antibody, we demonstrate a striking delay in B16 melanoma tumor growth and increased overall survival when compared with wild-type mice. This was also observed with antibodies targeting PD-1-PD-L1 and GITR. To highlight the therapeutic relevance of these findings, we show that CTLA-4 blockade strongly synergizes with IDO inhibitors to mediate rejection of both IDO-expressing and nonexpressing poorly immunogenic tumors, emphasizing the importance of the inhibitory role of both tumor- and host-derived IDO. This effect was T cell dependent, leading to enhanced infiltration of tumor-specific effector T cells and a marked increase in the effector-to-regulatory T cell ratios in the tumors. Overall, these data demonstrate the immunosuppressive role of IDO in the context of immunotherapies targeting immune checkpoints and provide a strong incentive to clinically explore combination therapies using IDO inhibitors irrespective of IDO expression by the tumor cells.

Harnessing the Immune System for the Treatment of Non–Small-Cell Lung Cancer

Over the last several years, new therapeutic targets have emerged in immunotherapy, particularly the immune checkpoint pathways. Blocking inhibitory pathways via monoclonal antibodies, such as the anti-cytotoxic T-lymphocyte antigen-4 antibody (ipilimumab), anti-programmed cell death-1 antibody (BMS-936558), and anti-programmed cell death-1 ligand antibody (BMS-936559), has the ability to break down the shield that tumors co-opt for their defense. Vaccines are able to help the immune system develop immune memory that can have long-lasting, tumor-specific effects. Newer vaccines, particularly the tumor cell vaccine, belagenpumatucel-L, and the antigen-specific vaccines, melanoma-associated antigen-A3, liposomal BLP-25, TG4010, and recombinant human epidermal growth factor, are being evaluated in some of the largest trials ever attempted in lung cancer therapy. These therapies alone or in combination may hold the key to making immunotherapy a reality in the treatment of lung cancer.

Improving Drug Uptake and Penetration into Tumors: Current and Forthcoming Opportunities

Improving Drug Uptake and Penetration into Tumors: Current and Forthcoming Opportunities

Radiologic Manifestations of Immune-Related Adverse Events in Patients With Metastatic Melanoma Undergoing Anti–CTLA-4 Antibody Therapy

Monoclonal antibodies against cytotoxic T-lymphocyte antigen 4 (CTLA-4) used for treatment of metastatic melanoma produce inflammatory immune-related adverse events. The purpose of the current study was to retrospectively identify and characterize the radiologic manifestations of immune-related adverse events and to evaluate the possible association between these events and clinical responses to anti-CTLA-4 therapy. We retrospectively reviewed the images and medical records of 119 patients with metastatic melanoma treated with anti-CTLA-4 at our institution and assessed the presence of radiologic manifestations of immune-related adverse events and the clinical responses to therapy. The responses were categorized as progressive or controlled disease. The controlled disease category included stable disease, partial response, and complete response according to the Response Evaluation Criteria in Solid Tumors, version 1.1. Radiologic manifestations of immune-related adverse events were found in 20 patients (16.8%). Clinically evident manifestations included colitis, hypophysitis, thyroiditis, and arthritis. Clinically silent manifestations were benign lymphadenopathy and inflammatory changes in the soft tissues, such as myositis, fasciitis, and retroperitoneal fat haziness. There was a significant association between the incidence of radiologic manifestations of immune-related adverse events and clinical responses to anti-CTLA-4 therapy. The disease control rates were 18% for the entire group, 55% for the group with, and 10% for the group without radiologic manifestations of immune-related adverse events. In three patients (2.5%), lymphadenopathy related to radiologic manifestations of immune-related adverse events was interpreted as suspected metastasis but was proved benign at biopsy. Radiologic manifestations of immune-related adverse events are associated with significant clinical benefit of anti-CTLA-4 therapy. In the era of developing immune checkpoint-targeted therapy for metastatic melanoma, radiologists should be alert to the possibility of these manifestations, which can mimic radiologic disease progression.

New Approaches to the Treatment of Pancreatic Cancer

The development of novel therapeutic strategies for pancreatic adenocarcinoma (PAC) has traditionally been considered particularly challenging for clinical and laboratory investigators due to its aggressive underlying biology and inherent resistance to currently available therapies. More recently, however, advances have been made in the identification of promising therapeutic targets for intervention, along with several key insights into the complex sequence of genetic alterations involved in the evolution of PAC from premalignant precursor lesion to malignant cells with metastatic potential. FOLFIRINOX (5-fluorouracil/leucovorin/irinotecan/oxaliplatin) has recently been identified as a combination cytotoxic therapy associated with a significant survival benefit over single-agent gemcitabine in good performance status patients with advanced disease; it is hoped that a similar benefit will be seen in planned trials of FOLFIRINOX as perioperative therapy. The success of immune therapy with the anti-cytotoxic T-lymphocyte antigen-4 antibody ipilimumab in advanced melanoma has spurred interest in the development of vaccines and immune therapies for other solid tumors. Certainly, the concept of harnessing the power of the immune system for cancer treatment is an attractive concept to patients and clinicians alike. Herein we discuss recent advances in the development of novel therapeutic approaches to PAC, focusing in particular on recent developments in immune and vaccine therapy.

Clinical Studies With Anti–CTLA-4 Antibodies in Non-melanoma Indications

Available medical treatments have limited impact on the survival of patients with advanced cancer; therefore, new therapeutic strategies able to generate more effective host's immune responses against neoplastic cells are being actively pursued. Among these, a recent approach involves targeting of cytotoxic T-lymphocyte antigen-4 (CTLA-4), a key immune checkpoint molecule, by monoclonal antibodies (mAbs). Ipilimumab and tremelimumab represent the prototypes of this new class of immunomodulating mAb and have been extensively tested in metastatic melanoma with highly promising results. The clinical activity observed in melanoma has served as a model to exploit the therapeutic potential of CTLA-4 blockade in a variety of human malignancies. Along this line, early-phase trials with anti-CTLA-4 mAbs have been completed or are ongoing in tumors of different histotype. Results are demonstrating the feasibility, safety, and activity of these agents, thus suggesting a promising therapeutic role to be further investigated in phase II/III trials in a wide range of tumors. This review summarizes the main trials with ipilimumab and tremelimumab in tumors of different histotypes, excluding cutaneous melanoma, which is extensively described in other chapters of this issue of Seminars in Oncology.

The Emerging Toxicity Profiles of Anti–CTLA-4 Antibodies Across Clinical Indications

The promising new class of immunomodulating antibodies directed against cytotoxic T-lymphocyte antigen-4 (CTLA-4) has been extensively tested in clinical trials and found to be active against cutaneous melanoma and other tumor histotypes. Inhibition of CTLA-4 characteristically induces well-identified side effects for which the definition "immune-related adverse events" (irAEs) has been proposed. IrAEs mainly include colitis/diarrhea, dermatitis, hepatitis, and endocrinopathies; uveitis, nephritis, and inflammatory myopathy also have been reported occasionally. These unique side effects are likely a direct result of breaking immune tolerance upon CTLA-4 blockade and are generally mild, reversible, and manageable, following specific treatment guidelines that include symptomatic therapies or systemic corticosteroids. However, patient-physician communication and early treatment are also emerging as critical issues to successfully manage irAEs, thus avoiding major complications. The major experience in identifying and managing CTLA-4 treatment-related side effects has derived from studies in melanoma patients; nevertheless, accumulating clinical experiences are clearly demonstrating that irAEs are class-specific events, and that they are fully overlapping in patients with tumors of different histotypes. This review provides an overview of current safety data on CTLA-4 antagonists and of available strategies to optimize their clinical use in cancer patients.

Immune regulatory antibodies: are they the next advance?

During the past decade, new insights into the mechanisms by which T-cell activation and proliferation are regulated have led to the identification of checkpoint proteins that either up- or down-modulate T-cell reactivity. In the presence of active malignancy, pathophysiologic inhibition of T-cell activity may predominate over stimulation. A number of antibodies have been generated that can block inhibitory checkpoint proteins or promote the activity of activating molecules. In murine models, their use alone or with a vaccine strategy has resulted in regression of poorly immunogenic tumors and cures of established tumors. The prototypical immune regulatory antibodies are those directed against cytotoxic T-lymphocyte antigen-4, a molecule present on activated T cells. In this review, the preclinical rationale and clinical experience with 2 anticytotoxic T-lymphocyte antigen-4 antibodies are extensively discussed, demonstrating that abrogation of an immune inhibitory molecule can result in significant regression of tumors and long-lasting responses. The unique kinetics of antitumor response and the characteristic immune-related side effects of ipilimumab are also discussed. This clinical efficacy of this promising antitumor agent has been evaluated in 2 randomized phase III trials, whose results are eagerly awaited. Programmed death (PD)-1 is another immune inhibitory molecule against which an abrogating human antibody has been prepared. Initial preclinical testing with anti-PD-1 and anti-PD-L1 has shown encouraging results. Stimulatory molecules such as CD40, 41-BB, and OX-40 are also targets for antibody binding and activation, not blockade, and early dose ranging trials with antibodies against all 3 have shown that they can mediate regression of tumors, albeit with their own spectrum of side effects that are different from those that occur with abrogation of immune inhibition.

Phase I Study of Ipilimumab, an Anti–CTLA-4 Monoclonal Antibody, in Patients with Relapsed and Refractory B-Cell Non–Hodgkin Lymphoma

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. 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). 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. 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.