Autoimmune Adverse Events Research Articles

Morphological changes of the thyroid gland as a new radiographic marker for lung cancer treatment efficacy of immune checkpoint inhibitors.

Fully human IgG4 programmed cell death-1 (PD-1) immune checkpoint inhibitors are effective against non-small-cell lung cancer (NSCLC). PD-1-targeted antibodies induce autoimmune adverse events that are not caused by conventional chemotherapy. To clarify the association between morphological changes of the thyroid gland and the efficacy of PD-1 immune checkpoint inhibitor treatment for lung cancer. The study enrolled 29 patients who received PD-1 immune checkpoint inhibitor treatment. The thyroid volume was measured using computed tomography (CT) at the following three timepoints: pre-treatment (baseline); three months after the initial administration (early treatment); and at the last CT scan during the observation period (late treatment). Thyroid volume ratios were calculated as follows: early treatment/baseline thyroid volume at CT (E/B-CT ratio) and late treatment/baseline thyroid volume at CT (L/B-CT ratio). Thyroid dysfunction was assessed according to thyroid hormone levels. The E/B-CT ratio was significantly higher in patients with adverse events of grade 3 or higher than in the other patients (P = 0.013). The L/B-CT ratio was significantly lower in patients with thyroid dysfunction than in those without thyroid dysfunction (P = 0.001). Complete response (CR) was achieved in three patients at the time of the final CT. The E/B-CT ratio was significantly higher in patients with CR than in the other patients (1.48 vs. 0.99, P = 0.029). Changes in thyroid volume after administration of PD-1 immune checkpoint inhibitors might be a useful radiographic marker of therapeutic efficacy in patients with lung cancer.

Systematic Review and Meta-analysis of Postlicensure Observational Studies on Human Papillomavirus Vaccination and Autoimmune and Other Rare Adverse Events.

Because of the limited number of subjects in prelicensure studies, autoimmune diseases and other rare adverse effects of vaccines may go undetected. Since 2006, millions of human papillomavirus (HPV) vaccine doses have been distributed and a considerable amount of postlicensure safety data has been generated. The objective of this study was to review available HPV postlicensure safety studies and to summarize risk estimates of autoimmune and other rare diseases. For this systematic review and meta-analysis, we searched literature databases to identify any postlicensure safety studies related to HPV vaccination and autoimmune adverse events from inception to April 16, 2019. Pooled risk estimates were computed using fixed- or random-effects models if at least 2 estimates per disease and per HPV vaccine were available. Twenty-two studies met our inclusion criteria. The studies applied various methodologies and used different types of data sources and outcome definitions. Quadrivalent HPV vaccine (4vHPV) was most commonly assessed. Type 1 diabetes mellitus, immune thrombocytopenia purpura and thyroiditis diseases were most frequently reported. The meta-analysis was conducted on 35 diseases corresponding to 48 pooled risk estimates. Majority of the pooled estimates showed no significant effect (n = 43). Three negative (paralysis, immune thrombocytopenia purpura and chronic fatigue syndrome) and 2 positive (Hashimoto and Raynaud diseases) associations were detected. Our study demonstrated an absence of clear association between HPV vaccines and autoimmune and other rare diseases. The review also highlights the need for more systematic collaborations to monitor rare safety adverse events.

VERY LATE PRESENTATION OF FULMINANT MYOCARDIAL IMMUNE-RELATED TOXICITY IN A PATIENT ON PEMBROLIZUMAB

Immune checkpoint inhibitors (ICI) can manifest as toxicity in the form of autoimmune, breakthrough or immune-related adverse events. A 59-year-old woman presented with worsening dyspnea on exertion for 1 week. Her medical history was significant for non-small cell lung carcinoma treated with

Immune Checkpoint Inhibitor Nephrotoxicity: Update 2020.

Immune checkpoint inhibitors (ICPIs) have transformed the landscape of oncology, but are associated with a variety of autoimmune adverse events, including AKI. ICPI-associated AKI (ICPI-AKI) is emerging as an increasingly frequent cause of AKI in patients with cancer, and poses unique diagnostic and management challenges to clinicians who care for these patients. In this review, we describe the incidence and risk factors for ICPI-AKI, including proton pump inhibitor use, CKD, and combination immunotherapy. We discuss the limitations of the various definitions used for ICPI-AKI in prior studies, and propose a novel classification system (definite, probable, and possible ICPI-AKI) that recognizes the diagnostic uncertainty inherent in many cases. We discuss the key clinicopathologic features and treatment strategies for ICPI-AKI, including the role of kidney biopsy versus empirical treatment with steroids. We also explore the under-studied area of ICPI use in the setting of solid organ transplantation, where nephrologists and oncologists must balance the risk of rejection versus treating the underlying malignancy. Finally, we summarize existing data on the role of ICPI rechallenge after an episode of ICPI-AKI.

Time to dissect the autoimmune etiology of cancer antibody immunotherapy.

Immunotherapy has transformed the treatment landscape for a wide range of human cancers. Immune checkpoint inhibitors (ICIs), monoclonal antibodies that block the immune-regulatory "checkpoint" receptors CTLA-4, PD-1, or its ligand PD-L1, can produce durable responses in some patients. However, coupled with their success, these treatments commonly evoke a wide range of immune-related adverse events (irAEs) that can affect any organ system and can be treatment-limiting and life-threatening, such as diabetic ketoacidosis, which appears to be more frequent than initially described. The majority of irAEs from checkpoint blockade involve either barrier tissues (e.g., gastrointestinal mucosa or skin) or endocrine organs, although any organ system can be affected. Often, irAEs resemble spontaneous autoimmune diseases, such as inflammatory bowel disease, autoimmune thyroid disease, type 1 diabetes mellitus (T1D), and autoimmune pancreatitis. Yet whether similar molecular or pathologic mechanisms underlie these apparent autoimmune adverse events and classical autoimmune diseases is presently unknown. Interestingly, evidence links HLA alleles associated with high risk for autoimmune disease with ICI-induced T1D and colitis. Understanding the genetic risks and immunologic mechanisms driving ICI-mediated inflammatory toxicities may not only identify therapeutic targets useful for managing irAEs, but may also provide new insights into the pathoetiology and treatment of autoimmune diseases.

Combined immune checkpoint inhibitor therapy with nivolumab and ipilimumab causing acute-onset type 1 diabetes mellitus following a single administration: two case reports

BackgroundThe use of immune checkpoint inhibitor (ICI) therapy is becoming a standard of care for several cancers. Monoclonal antibodies targeting cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed cell death protein 1 (PD-1) or its ligand (PD-L1) cause a broad spectrum of autoimmune adverse events. ICI-induced type 1 diabetes mellitus (T1DM) is extremely rare (< 1%) but potentially life-threatening. It appears to be more common with PD-1 blockade (or combination immunotherapy) than with anti-CTLA-4 therapy, often during the first three to six months of therapy.Cases presentationWe report an acute onset T1DM with severe inaugural diabetic ketoacidosis (DKA) and remarkably elevated Glutamic Acid Decarboxylase antibody (GADA) titres following a single administration of combined ICI therapy with nivolumab (anti-PD-1) and ipilimumab (anti-CTLA-4) in two adult patients with advanced metastatic melanoma. In these cases, the time to diabetes onset was remarkably short (two and five weeks), and one presented with fulminous T1DM in a previous long-standing type 2 diabetes mellitus.ConclusionsOncological patients treated with combination therapy of anti-PD-1 and anti-CTLA-4 can develop a particular pattern of T1DM, with very rapid onset within a few weeks after starting ICI therapy, even in the presence of an existing type 2 diabetes. ICI-induced T1DM is a medical emergency in presence of severe inaugural DKA and requires a collaboration between specialists and primary care physicians, as well as patient education, for early diagnosis and supportive care.

Alemtuzumab treatment of multiple sclerosis in real-world clinical practice: A report from a single Italian center

BackgroundAlemtuzumab, is a compound approved for highly active MS, and, in Europe, employed after the use of other disease-modifying treatments (DMTs) with an escalation approach or used as a first therapeutic option. The occurrence of secondary autoimmune adverse events and or infections can differ depending on the employed approach. ObjectiveTo evaluate the efficacy and safety of alemtuzumab in real-world MS population that encompassed patients previously treated with other DMTs. Methods35 patients, treated with alemtuzumab in a single MS Center, were followed for at least 36 months. The study investigated the prevalence of patients reaching the phase of the non-active disease (NEDA-3). All the adverse events were also reported, and correlations assessed. ResultsAt the 36-month follow-up, 66,7% of patients achieved the NEDA-3 status, 90,5% of the patients were relapse-free, 85,7% showed no signs of disability progression, nor signs of MRI activity. Adverse events were observed in 45,7% of the patients and ranked as severe in 23% of them. Cases of autoimmune hemolytic anemia (AIHA), pancytopenia, viral hepatitis E, and noninfectious meningo-encephalomyelitis were found and reported. For these complications, the post hoc analysis showed possible interactive factors and causality related to previous DMT treatments. ConclusionsIn a real-world MS population like the one investigated in our study, alemtuzumab was found to be an effective treatment when employed as an escalation or rescue therapy. The compound exhibits a variable safety profile and frequent adverse events that are likely depending on previous treatments and their impact on the immune system.

Lymphocyte pharmacodynamics are not associated with autoimmunity or efficacy after alemtuzumab

ObjectiveTo examine the association between peripheral blood lymphocyte pharmacodynamics and autoimmune adverse events (AEs) or return of disease activity in alemtuzumab-treated patients with relapsing-remitting MS.MethodsPatients received 2 alemtuzumab courses (12 mg/d IV; 5 days at baseline, 3 days 12 months later) in the 2-year Comparison of Alemtuzumab and Rebif Efficacy in Multiple Sclerosis studies (NCT00530348 and NCT00548405) and could then receive as-needed alemtuzumab or other disease-modifying therapy in a 4-year extension (NCT00930553). Lymphocytes were phenotyped quarterly over 2 years using fluorescence-activated cell sorting. Pharmacodynamic assessments included counts of total lymphocytes, CD3+ T cells, CD4+/CD8+ T cells (total/naive/memory/regulatory [Treg]), and CD19+ B cells (total/immature/mature/memory) and ratios of CD19+ (total/immature/mature/memory) to Treg (CD4+/CD8+) counts. Assessed autoimmune AEs included immune thrombocytopenia, nephropathies, and thyroid events. Efficacy assessments included relapses, 6-month confirmed disability worsening (CDW), and MRI disease activity.ResultsLymphocyte repopulation patterns, including ratios between distinct lymphocyte subsets (e.g., CD19+ to Treg cell count ratios), showed no significant differences over 2 years in patients developing/not developing autoimmune AEs, relapses, CDW, or MRI activity through 6 years following alemtuzumab. Lymphocyte kinetics were also unrelated to multiple autoimmune AEs or extreme clinical phenotypes.ConclusionsRepopulation kinetics of the evaluated peripheral lymphocyte subsets did not predict autoimmune AE occurrence or disease activity, including return of disease activity after 2 alemtuzumab courses. Further study is needed to investigate potential antigen-level markers of treatment response.

The Effect of Antibody Fragments on CD25 Targeted Regulatory T Cell Near-Infrared Photoimmunotherapy.

Regulatory T (Treg) cells play a major role in immune suppression permitting tumors to evade immune surveillance. Depletion of intratumoral Treg cells can result in tumor regression. However, systemic depletion of Tregs may also induce autoimmune adverse events. Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed cell-specific cancer therapy that locally kills specific cells in the tumor. Antibody-photoabsorber (IRDye700DX) conjugates (APC) are injected and bind to the tumor, and subsequent administration of NIR light to the tumor results in rapid cell death only in targeted cells. CD25-targeted NIR-PIT has been shown to induce spatially selective depletion of tumor-associated Treg cells. In this study, we compared the efficacy of an antibody fragment, anti-CD25-F(ab')2, and a full antibody, anti-CD25-IgG, as agents for NIR-PIT. Tumor-bearing mice were divided into four groups: (1) no treatment; (2) anti-CD25-IgG-IR700 i.v. only; (3) anti-CD25-F(ab')2-IR700 i.v. with NIR light exposure; and (4) anti-CD25-IgG-IR700 i.v. with NIR light exposure. Although both CD25-targeted NIR-PITs resulted in significant tumor growth inhibition, the anti-CD25-F(ab')2-IR700 based NIR-PIT was superior to the anti-CD25-IgG-IR700 NIR-PIT. The anti-CD25-F(ab')2-IR700 demonstrated faster clearance from the body than the anti-CD25-IgG-IR700. Sustained circulation of anti-CD25-IgG-IR700 may block IL-2 binding on the activated effector T-cells decreasing immune response. In conclusion, anti-CD25-F(ab')2 based NIR-PIT was more effective in reducing tumor growth than anti-CD25-IgG based NIR-PIT. Absence of the Fc portion of the APC leads to faster clearance and therefore promotes a superior activated T cell response in tumors.

Abstract 3167: Improving and standardizing TMB assay performance

Abstract Determining and using the most effective and safest treatment is of great importance in cancer disease management. Checkpoint inhibitors that target immune regulatory molecules such as PD-1, PD-L1, and CTLA-4, have successfully improved PFS and OS - but only in some patients and for some cancers. In the case of PD-1 and PD-L1 inhibitors, it is believed that PD-L1 expression by a solid tumor allows it to escape attack from the immune system and that by inhibiting the PD-L1/PD-1 interaction immune evasion is no longer possible. This may then cause some of the mutations that give rise to expressed neoantigens to act as targets for T cells and allow for the gradual elimination of the tumor. Since the risk for developing autoimmune adverse events is not insignificant with the use of checkpoint inhibitors, determining which patients are likely to respond favorably to their use is imperative. Similarly, expanding approved uses to new indications also benefits from the identification of populations that are most likely to show improvement in PFS and OS - generally, through clinically-validated biomarkers. Current indications for the use of PD-1 and PD-L1 inhibitors rely on cancer type and several biomarkers. One of these is the expression (or level of expression) of PD-L1 on the tumor. Another - usually in colorectal cancer - is the presence of microsatellite instability (MSI), which indicates that DNA is not being copied with high fidelity and resulting mutations may lead to the emergence of potential neoantigens. While MSI can be assessed by the PCR amplification of several loci, the presence or absence of neoantigens cannot, and they can also be created in the absence of MSI. This has given rise to a potential biomarker - tumor mutational burden (TMB) - that is an assessment of the number of relevant mutations in a tumor. TMB measurement is challenging since different targeted next generation sequencing (NGS) panels look at different regions and percentages of the genome and use different criteria as to what constitutes a relevant mutation. Presently, there is poor correlation between different TMB assays at mutation levels that may be relevant for a companion diagnostic where patients may be denied treatment. Here, we describe the characterization of a panel of reference materials for the assessment, harmonization, and improvement of TMB measurements by NGS assays. The panel is comprised of cancer cell lines and their SNP-matched normals. DNA from unfixed cells was used to establish a baseline truth set of somatic mutations and germline SNPs, and DNA from FFPE cells was used to determine how TMB assessment is affected by fixation artifacts - especially, at lower variant allele frequencies. We present data from high coverage whole exome sequencing - the current gold standard in TMB assessment - and from targeted NGS panels that are more typical of what may be used clinically. We show that accurate measurements at what may be clinically relevant TMB cutoffs remain a challenge. Citation Format: Matthew G. Butler, Yves Konigshofer, Lequan Nguyen, Shikha Kalotra, Omo Clement, Russell K. Garlick, Bharathi Anekella. Improving and standardizing TMB assay performance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3167.

Association between past medical history (PMH) of autoimmune events and adverse events of special interest (AESI).

2565 Background: PD-1/L1 inhibitor therapy has become the standard of care for many advanced solid tumors. A notable limitation of PD-1/L1 inhibitor therapy is the concern for AESI that are likely to be immune related. It is unclear whether a history of autoimmune events is a predisposing risk making these adverse events more likely. We aimed to evaluate the association between autoimmune-associated PMH and AESI on PD-1/L1 inhibitors. Methods: We pooled data across seven pivotal trials for PD-1/L1 inhibitors in urothelial cancer (UC) identifying patients with AESI submitted from 2016 - 2017. AESI were determined using a pooled preferred term list for each trial. Information collected from trials included PMH, AESI events and toxicity grade. Results: In total, 1747 immunotherapy treated patients were identified, with 1068 (61%) having an AESI and 277 (26%) having an autoimmune-related PMH. The most common autoimmune-associated events in the PMH were thyroid disorders (64%), asthma (23%), atopic dermatitis/eczema (6%), irritable bowel syndrome (5%), and psoriasis (4%). AESI occurred in 68% of patients with an autoimmune-related PMH and 60% of patients without an autoimmune-related PMH. The most common AESI in patients with an autoimmune-related PMH were diarrhea (35%), rash (27%), renal disorder (27%), and pruritis (23%). The most common AESI in the general trial population were diarrhea (28%), pruritis (26%), rash (25%), increased creatinine (14%), and elevated AST and ALT (10% and 9%). The majority of events were Grade 1-2 (87% in patients with an autoimmune-related PMH and 84% in the general trial population). Conclusions: Pooled clinical trial data shows a slight numeric increase in AESIs in patients with autoimmune-associated PMH. Limitations include potential lack of consistency of PMH documentation and adverse event reporting. There did not appear to be a pattern of association between PMH and type of AESI event. Grades of AESI events in the population with autoimmune-associated PMH were similar to the general trial population. This suggests that PD-1/L1 inhibitors may be safely administered to patients with UC and a PMH of some autoimmune-associated events. Further exploration is needed.

Cancer immunotherapy with check point inhibitor can cause autoimmune adverse events due to loss of Treg homeostasis

Regulatory T-cells (Tregs) can facilitate immune evasion by tumor cells by dampening anti-tumor immunity. Reduced Teff/Treg ratio and enhanced Treg functional activity have been observed in patients suffering from different types of cancers, and attenuated Treg numbers/functions can serve as prognostic indicators. Normally, Tregs play an essential role in the maintenance of immune tolerance and prevention of autoimmunity. The most common immune checkpoint blockers (ICB) targeting co-inhibitory receptors such as anti-CTLA4 (ipilimumab and tremelimumab) and anti-PD1 (pembrolizumab and nivolumab)/anti-PD-L1 (atezolizumab) have achieved unprecedented success in cancer treatment by facilitating an effective anti-tumor immune response, at least in part, by blocking Treg mediated immunosuppression. While ICBs have shown remarkable success in cancer immunotherapy, immune-related adverse events (IRAEs) arising from ICB have forced consideration of ways to maintain immune homeostasis post ICB treatment. Preclinical models of IRAEs have shown a negative correlation between Treg numbers and IRAEs. Therefore, understanding the "ying-yang" role of Tregs in the regulation of autoimmunity and anti-tumor immunity is critical to provoking an effective anti-tumor response while maintaining immune homeostasis. Studies aimed at developing effective approaches to minimize IRAEs without compromising anti-tumor immunity are underway. Herein, we discuss 1) the critical role of key co-inhibitory receptors on Treg homeostasis and tumor tolerance; 2) how co-receptor blockade by cancer immunotherapy can lead to autoimmune adverse events; and 3) recently emerging management strategies to minimize autoimmune adverse events arising from ICB.

Preliminary Clinical Results of a Phase 1 Study Evaluating the Safety and Anti-Tumor Activity of ACTR707 in Combination with Rituximab in Subjects with Relapsed or Refractory CD20+ B-Cell Lymphoma

Preliminary Clinical Results of a Phase 1 Study Evaluating the Safety and Anti-Tumor Activity of ACTR707 in Combination with Rituximab in Subjects with Relapsed or Refractory CD20+ B-Cell Lymphoma

Efficacy and Toxicity of JCAR014 in Combination with Durvalumab for the Treatment of Patients with Relapsed/Refractory Aggressive B-Cell Non-Hodgkin Lymphoma

Efficacy and Toxicity of JCAR014 in Combination with Durvalumab for the Treatment of Patients with Relapsed/Refractory Aggressive B-Cell Non-Hodgkin Lymphoma

CADD-23. PD-L1 CHECKPOINT BLOCKADE USING A SINGLE-CHAIN VARIABLE FRAGMENT TARGETING PD-L1 DELIVERED BY RETROVIRAL REPLICATING VECTOR (TOCA 521) ENHANCES ANTI-TUMOR EFFECT IN CANCER MODELS

Conventional interventions for treating glioblastoma (GBM) patients has had limited success, with a median overall survival of 15–17 months. Recently, immune checkpoint inhibitors (CPIs) showed long-term response rates from 20–30% in some tumors, but no consistent clinical benefit with these agents has been demonstrated so far in GBM patients. We propose and provide preliminary evidence for a strategy using retroviral replicating vectors (RRV) to deliver CPI agents selectively to cancer cells that may circumvent such issues. An RRV encoding a single-chain variable fragment targeting PD-L1 (RRV-scFv-PDL1, Toca 521) binds to both mouse and human PD-L1 by competitive ELISA and competes for target occupancy with a commercially available monoclonal antibody against cell surface PD-L1. A dose-dependent bystander effect is observed with scFv PD-L1 protein expressed from RRV-scFv-PDL1 infected tumor cells showing saturated receptor binding to the cell surface PD-L1 of bystander cells when co-cultured with as low as 10% scFv PD-L1 expressing cells. In addition, the immune functional activity of scFv PD-L1 to reverse PD-1/PD-L1 mediated immune suppression was observed in a co-culture system in vitro and further supported by in vivo mouse models. Such models included a syngeneic orthotopic glioma showing that tumors infected with RRV-scFv-PDL1 conferred robust and durable immune-mediated antitumor activity superior to systemically administered anti-PD-1/anti-PD-L1 monoclonal antibodies. These results support the concept that RRV-scFv-PDL1 CPI strategy may provide an improved safety and efficacy profile compared to systemic monoclonal antibodies. The superior anti-tumor activity of RRV-scFv-PDL1 may be due to consistent high levels of scFv PD-L1 within the tumor microenvironment. This localized delivery approach with less concern for autoimmune adverse events may be therapeutically beneficial as an immuno-oncology agent either alone or in combination.

Belatacept and Autoimmune Adverse Events

Belatacept is widely used to prevent rejection in kidney transplants with its excellent tolerability profile. Here, we report a severe psoriasis manifesting in a kidney transplant recipient raising the possibility of belatacept-induced autoimmunity. Our patient was a 42-year-old man with an end-stage renal disease secondary to anti neutrophil cytoplasmic antibody-associated vasculitis. In January 2014, more than 2 years after receiving rituximab as treatment, he underwent primary renal transplantation (with 1 B mismatch). Immunosuppressive induction therapy consisted of anti-IL2R (basiliximab), whereas maintenance therapy consisted of mycophenolic acid and tacrolimus delivered at their standard regular dosages. On day 10 postoperation, a graft biopsy revealed marked thrombotic microangiopathy. Tacrolimus toxicity was suspected and tacrolimus was substituted with belatacept (5 mg/kg monthly) with an excellent result (serum creatinine, 100 μmol/L). In September 2014, physical examination revealed psoriatic plaques, confirmed by skin biopsy. Topical treatment with calcipotriol was introduced. In July 2016, because of a deterioration in his skin condition, we decided to stop mycophenolic acid and commence ciclosporin. Despite an initial improvement, the psoriasis progressively deteriorated (Figure 1). Therapeutic strategies were constrained, because in this transplant recipient, phototherapy and most biologic therapies were contraindicated. In February 2017, we decided to stop belatacept and reintroduce mycophenolic acid. A few weeks after its discontinuation, the plaques progressively disappeared, and complete resolution was finally observed.FIGURE 1: Diffuse well-demarcated psoriasis form plaques.Several factors suggest a casual association between this exposure and the development of the lesions: (i) our patient had neither a personal nor familial history of psoriasis; (ii) its onset at 7 months of costimulation blockade could be plausible (see below); (iii) rapid improvement was observed after its removal; (iv) a biological plausibility to explain this effect can be found. Psoriasis has been reported in patients with rheumatoid arthritis treated with abatacept.1 Regarding the pooled safety data of the BENEFIT trials, a similar frequency of autoimmune-related adverse events (AEs) between belatacept-treated recipients and ciclosporin-treated controls has been observed. However, psoriasis was the most common autoimmune disorder to manifest in belatacept-treated patients, whereas hyperthyroidism was the most frequent to manifest in controls. In the susceptible patient, belatacept could dysregulate immunity in different ways. First, by inhibiting regulatory T (Treg) cells either quantitatively or qualitatively.2 Indeed, abatacept and belatacept are both CTLA4-Ig fusion proteins antagonizing CD80-86, the ligand for CD28 (essential to Treg generation and maintenance) and CTLA-4 (crucial for Treg functions). Second, belatacept blocks the CTLA-4 inhibitory pathway on memory T cells. Belatacept-resistant rejection is thought to be due to alloreactive memory T cells, which are less dependent on CD28 signaling for their activation and are regulated by CTLA-4 intrinsic mechanisms.3 Krummey and Cheeseman4 demonstrated that interleukin 17-secreting T helper (Th17) cells are especially sensitive to CTLA-4 coinhibition and resistant to costimulation blockade. Psoriasis and inflammatory bowel disease, for which a belatacept-induced case has been recently reported,5 are both Th17 mediated. Pharmacovigilance in the “real life” transplant setting often yields new safety concerns about rare drug-related adverse events. Transplant community physicians should be aware that the use of belatacept after kidney transplantation may be implicated in psoriasis occurrence. Patient data were obtained from the DIVAT clinical cohort (divat.fr) ethically approved: N8CNIL 891735 version 2, August 2004.

Abstract 2711: Development of a new innovative multifunctional immune checkpoint inhibitor

Abstract Blockade of PD-1, PD-L1 or CTLA-4 is an attractive strategy for Immuno-Oncology (I-O) therapy. Moreover, combination approaches, which inhibit non-redundant pathways of PD-1/PD-L1 and CTLA-4, have been reported to show enhanced anti-tumor activity as well as improved progression-free survival in clinical trials of melanoma. The use of immune checkpoint blockade (ICB) drugs, however, can lead to severe or life-threatening complications of autoimmune disorders such as diabetes, thyroiditis, pulmonary fibrosis and vitiligo. Therefore, new innovations are critical to overcome possibilities of unintended immunoactivation and minimize drug cross-reactions and complications. Here, we designed and synthesized a novel alkylating Pyrrole-Imidazole (PI) polyamide with indole-seco-CBI capable of disrupting expressions of human PD-1, PD-L1 and CTLA-4 genes (CCC07-01) by binding to a common motif. Our initial evaluation process confirmed that the induction of tumor- and tumor-environment-specific combinatorial ICB therapy was possible by only a single agent. CCC07-01 administration significantly suppressed PD-1, PD-L1 and CTLA-4 mRNA and protein expressions at low nanomolar doses (15, 10, 5 nM respectively) in several cell lines. Furthermore, logP characterization experiments found CCC07-01 to be sufficiently lipophilic that enhanced the molecule's capability to accumulate and be retained in tumor tissues. Additionally, elevated doses of CCC07-01 induced substantial cytotoxicity in SW480, RKO and A2058 cancer cells (IC50=27, 12 and 11 nM, respectively) but primary cells derived from normal human tissues were not affected. These results illuminated the therapeutic possibility of CCC07-01 through, at low doses, its anti-tumor effect in tumor microenvironments and generalized cytotoxicity at increased dosage levels. CCC07-01's enhanced retention in tumor may also contribute to lower risks of triggering adverse autoimmune events compared to other ICB approaches. Preliminary results from human RKO colon carcinoma xenograft NGS mice, following the engraftment of human HLA-matched peripheral blood mononuclear cells (PBMC), showed significant tumor reduction 14 days after the injection of CCC07-01 (2.3 mg/kg, p &amp;lt; 0.05) and displayed detectable amounts of predominant effector memory CD8 T cells in the spleen 14 days post-administration (9.2 mg/kg, p &amp;lt; 0.05). The approach of simultaneously targeting elements in immune checkpoints, as demonstrated by CCC07-01, can lead to new therapeutic opportunities and reduce healthcare costs by curbing undesired autoimmune complications. Together with Zenyaku Kogyo, we envision a breakthrough in the field of current antibody-based ICB therapy as we continue to evolve and improve the use of PI polyamides as a viable candidate for ICB. Citation Format: Hiroki Nagase, Keiko Fukushima, Asuka Hattori, Mayu Shinohara, Atsushi Takatori, Takayoshi Watanabe, Nobuko Koshikawa, Takahiro Inoue, Jason Lin, Yoshinao Shinozaki. Development of a new innovative multifunctional immune checkpoint inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2711.

Use of immune checkpoint inhibitors in thymic epithelial tumors

Thymic malignancies represent a heterogeneous group of rare thoracic cancers, which may be aggressive and difficult to treat. Thymic carcinomas are more aggressive tumours with frequent metastatic spread to lymph nodes and distant sites. In this setting, the use of immune checkpoint inhibitors has been considered a potential strategy for the treatment of those tumors. Overall, while immune checkpoint inhibitors targeting PD-1 or PD-L1 show promising efficacy, with response rates and duration of response in line with reported studies in other solid tumours, toxicity remains a major concern, despite systematic baseline workup for autoimmunity, with frequent occurrence of severe auto-immune adverse events. Therefore, immunotherapy is currently not a standard-of-care in thymic epithelial tumors, and should be further studied in clinical trials.

Long-amplicon TCRβ repertoire sequencing to reveal human T-cell receptor variable gene polymorphism: Implications for the prediction and interpretation of immunotherapy outcome.

129 Background: Human T cell antigen receptors play a critical role in protective immune responses but are also implicated in autoimmune disease and immune-mediated adverse events during immunotherapy. The antigen specificity of the T cell receptor is determined in part by the sequence of the CDR and Framework regions encoded by the TCRB variable gene. Previous studies of population sequencing data indicate that current antigen receptor allele databases, such as IMGT, fail to capture a significant portion of human variation. Here we use long-amplicon multiplex sequencing of rearranged TCRB receptors to validate putative novel human variable gene alleles previously recovered from 1000 genomes data. Methods: TCRB rearrangements were amplified from cDNA from 85 Caucasians undergoing treatment for melanoma using AmpliSeq-based multiplex Framework 1 and Constant gene primers to produce ~330bp amplicons. Samples were sequenced using the Ion Torrent S5 530 chip to produce ~1.5M raw reads per sample. Ion Reporter was used for clonotyping and identification of variable gene sequences absent from the IMGT database. Putatively novel sequences were compared to those reported in the Lym1k database of alleles recovered from 1000 genomes data. Results: We identified 15 novel variable gene alleles that are absent from the IMGT database and result in amino acid changes to the CDR or Framework regions of the TCR. Typically, a single individual was found to be heterozygous for a novel variant, though we note two instances where multiple individuals possessed a novel variant. We also identified novel variable gene alleles that are absent from the Lym1k database, potentially due to challenges in inferring receptor alleles from short-read population sequencing studies. Conclusions: We find evidence for significant human diversity in TCRB variable gene alleles beyond what is currently represented in the IMGT database. TCRB sequencing using multiplex Framework 1 and Constant gene targeting primers is ideally suited for studying the role of TCRB polymorphism in autoimmune disease and immune-mediated adverse events during immunotherapy.

Management of immune thrombocytopenia in multiple sclerosis patients treated with alemtuzumab: a Belgian consensus

Alemtuzumab (Lemtrada®) is a humanized monoclonal antibody indicated for the treatment of adult patients with relapsing–remitting multiple sclerosis with active disease defined by clinical or imaging features. Alemtuzumab demonstrated superior efficacy over active comparator in both treatment naive patients and those with inadequate response to prior therapy. Alemtuzumab is associated with a consistent and manageable safety and tolerability profile. Treatment with alemtuzumab for multiple sclerosis increases the risk for autoimmune adverse events including immune thrombocytopenia (ITP). Complete blood counts with differential should be obtained prior to initiation of treatment and at monthly intervals thereafter for 48 months after the last infusion. After this period of time, testing should be performed based on clinical findings suggestive of ITP. If ITP onset is confirmed, appropriate medical intervention should be promptly initiated, including immediate referral to a specialist. This paper presents the consensus of Belgian multiple sclerosis specialists and hematologists to guide the treating physician with practical recommendations.