CTLA-4 Blockade Research Articles

Distinct Cytokine Signatures in Thyroiditis Induced by PD-1 or CTLA-4 Blockade: Insights from a New Mouse Model.

Background: The pathogenesis of thyroiditis caused by immune-checkpoint inhibitors (ICIs) such as antiprogrammed death receptor-1 (PD-1) and anticytotoxic T lymphocyte antigen-4 (CTLA-4) is incompletely understood. To gain mechanistic insights, we developed a mouse model of ICI-related thyroiditis and assessed the clinical, hormonal, and cytokine profiles. Methods: Forty NOD-H2h4 mice, 112 days old at the start of the experiments, were divided into two sequential cohorts. In the first one (No. = 21), mice were injected with both anti-PD-1 and anti-CTLA-4 checkpoint inhibitors while drinking either regular water or iodine-supplemented water. In the second cohort (No. = 19), mice were injected with either anti-PD-1 or anti-CTLA-4 while drinking iodine-supplemented water. Mice were sacrificed two months after the initial injection to collect thyroid gland for histopathology (to assess thyroiditis severity) and flow cytometry (to identify immune cell subsets and tissue-resident memory T cell markers). Mice were also studied before sacrifice to determine thyroid area and structure (by ultrasound), thyroid function (serum total thyroxine, thyrotropin, thyroid antibodies), and cytokine profile (by bead-based Luminex technology). Results: Thyroiditis was more severe upon PD-1 than CTLA-4 blockade (p = 0.01) and significantly correlated with the number of CD45+ cells infiltrating the thyroid (cumulative odds ratio [OR] 1.2 [95% confidence interval, CI 1.1-1.3], p < 0.001, that is 20% greater odds of a higher severity score for every 170-unit increase in CD45 infiltrating cells). Thyroiditis was instead more prevalent (100% vs. 63%, p < 0.01) in the anti-CTLA-4 mice, which also showed a larger thyroid area (17 ± 8.2 mm) than those treated with anti-PD-1 (11 ± 4.2 mm) and controls (p < 0.01). Serum IL-6 was markedly increased upon PD-1 blockade (40 pg/mL at baseline, 198 pg/mL on day 172), an increase not seen in the anti-CTLA-4 group (p = 0.01). IL-6 mirrored thyroiditis severity, with highest serum values found in greatest histopathology scores (cumulative OR 1.1 [CI 1.02-1.15], p = 0.009). GM-CSF and MIP1β increased more in the anti-CTLA-4 group (p < 0.001 for both), whereas the other cytokines did not differ among the treatment groups. Conclusions: The study reports a mouse model of thyroiditis induced by PD-1 blockade and, comparing it to the anti-CTLA-4 model, uncovers distinctive histopathological, sonographic, hormonal, and immunological features, offering biomarkers, such as serum IL-6, that could be used in the clinical setting.

Combined CTLA-4 and PD-L1 blockade in patients with chemotherapy-naïve metastatic castration-resistant prostate cancer is associated with increased myeloid and neutrophil immune subsets in the bone microenvironment

BackgroundImmune checkpoint therapy (ICT) has low response rates in patients with metastatic castration-resistant prostate cancer (mCRPC), in part due to few T cells in the tumor microenvironment (TME). Anti-cytotoxic T...

Immune landscape in vulvar cancer-draining lymph nodes indicates distinct immune escape mechanisms in support of metastatic spread and growth

BackgroundTherapeutic immune intervention is highly dependent on the T-cell priming and boosting capacity of tumor-draining lymph nodes (TDLN). In vulvar cancer, in-depth studies on the immune status of (pre)metastatic TDLN...

S2707 A Case of Fatal Immune Checkpoint Inhibitor Mediated Hepatitis

Introduction: Immune checkpoint inhibitors (ICPI) have become mainstays of therapy for advanced malignancies including melanoma, lung cancer, and renal cell carcinoma. Although they have shown promising mortality benefit, their risk of serious immune-related toxicities, including hepatitis, is increasingly documented in the literature. Case Description/Methods: A 27-year-old man with stage IV renal cell carcinoma on nivolumab/ipilimumab was transferred from state prison for acute transaminitis and hyperbilirubinemia. Prison records showed AST 3267, ALT 2236, and total bilirubin 5.9, increased from AST 113 and ALT 156 two weeks prior. On presentation the patient endorsed generalized abdominal pain and fatigue. Sclera were icteric and the abdomen was diffusely tender to palpation without organomegaly. Abdominal ultrasound revealed mild hepatomegaly, elevated hepatic artery velocity, and numerous gallstones. Broad work up to exclude other etiologies of liver failure was negative. Treatment included high-dose solumedrol, mycophenolate mofetil, n-acetylcysteine, and ursodiol. Transaminases improved but bilirubin worsened to >34. Repeat abdominal ultrasounds showed no biliary obstruction. An MRCP was non-diagnostic due to procedural intolerance. Hospital course was complicated by encephalopathy, septic shock from bacteremia, renal failure and disseminated intravascular coagulation. The patient was not a transplant candidate due to metastatic malignancy. He transitioned to comfort-oriented measures and expired within 24 hours. Discussion: ICPI mediated hepatitis is typically asymptomatic and occurs 6-14 weeks following treatment initiation, as was the case in our patient. Treatment is guided by the severity of hepatic injury as represented by transaminase and bilirubin levels (Grades 1-4) and typically involves medication discontinuation and steroid administration. Severe disease is also treated with mycophenolate mofetil. Acute hepatitis occurs in less than 5-10% of patients receiving a single ICPI, with 1-2% experiencing grade 3-4 hepatitis. However, grade 3-4 hepatitis has been observed in approximately 20% of patients receiving ipilimumab + nivolumab, consistent with previous findings that combination CTLA-4 and PD-1 blockade is associated with more frequent and more severe immune-related toxicities. This case illustrates a rare but important complication of dual ICPI therapy that, if not promptly diagnosed and treated, can be fatal.Figure 1.: Mechanisms of Action of Ipilimumab and Nivolumab.

Targeting TIGIT for Immunotherapy of Cancer: Update on Clinical Development.

Immune checkpoint blockers have dramatically improved the chances of survival in patients with metastatic cancer, but only a subset of the patients respond to treatment. Search for novel targets that can improve the responder rates and overcome the limitations of adverse events commonly seen with combination therapies, like PD-1 plus CTLA-4 blockade and PD-1/PD-L1 plus chemotherapy, led to the development of monoclonal antibodies blocking T-cell immunoglobulin and ITIM domain (TIGIT), a inhibitory checkpoint receptor expressed on activated T cells and NK cells. The strategy showed potential in pre-clinical and early clinical studies, and 5 molecules are now in advanced stages of evaluation (phase II and above). This review aims to provide an overview of clinical development of anti-TIGIT antibodies and describes the factors considered and thought process during early clinical development. Critical aspects that can decide the fate of clinical programs, such as origin of the antibody, Ig isotype, FCγR binding, and the dose as well as dosing schedule, are discussed along with the summary of available efficacy and safety data from clinical studies and the challenges in the development of anti-TIGIT antibodies, such as identifying patients who can benefit from therapy and getting payer coverage.

860MO Preoperative durvalumab (D) with or without tremelimumab (T) for resectable head and neck squamous cell carcinoma (HNSCC)

Although antibodies that block PD-1/PD-L1 axis improve survival in patients with recurrent and/or metastatic HNSCC, safety and efficacy of neoadjuvant immunotherapy with PD-L1 with or without CTLA-4 blockade has not been explored. Here, we evaluate the safety and efficacy of a single dose of preoperative D with or without T (D+/-T) in patients with resectable HNSCC. Patients with locally advanced but resectable HNSCC were eligible. Enrolled patients were randomized into D or D+T, stratified by primary site and human papilloma (HPV) infection status. A single dose of preoperative D (1500mg) or D+T (1500mg+75mg) was administered, with surgery planned 2 to 8 weeks later for curative resection. Postoperative (chemo) radiation was prescribed based on standard guidelines, followed by maintenance with D every 4 weeks for 1 year. The primary objective was to determine the local recurrence rate. Secondary endpoints included pathologic response, safety, tolerability, survival outcome, and exploration of immune dynamics. As of May 14, 2021 for interim analysis, a total of 44 patients were enrolled and received surgical resection with available data for pathologic response (D: 20 patients, D+T: 24 patients). Oropharyngeal cancer was most common (n=22), followed by hypopharyngeal (n=9), oral cavity (n=8), and laryngeal cancer (n=5). Human papilloma virus-mediated cancer was observed in 20 patients (45.4%). Neaoadjuvant D+/-T had an acceptable safety profiles and was not associated with delays in surgery or unexpected adverse events. Tumor shrinkage was observed in 31 patients (70.5%), with 16.0% of average tumor shrinkage (95% CI; 4.7% to 27.3%) in the overall population. Major pathologic response (no more than 10% of viable tumor cells) was achieved in 3 patients (6.8%), including 2 cases with pathologic complete response (4.5%). During median follow-up duration of 176 days after surgery, local recurrence was documented in 2 patients (4.5%). These early data suggested that preoperative D+/-T was safe and feasible and had the potential to provide clinical benefits for patients with resectable HNSCC. The trial is ongoing and the updated outcomes with immune correlates will be presented with ESMO.

1069P Granulomatous and sarcoid-like immune adverse events following CTLA4 and PD1 blockade adjuvant therapy of high-risk melanoma: A combined analysis of ECOG-ACRIN E1609 and SWOG S1404 phase III trials

Treatment with immune checkpoint inhibitors (ICIs) has been linked to granulomatous and sarcoid-like lesions (GSL) affecting the skin, lungs, thoracic lymph nodes, eyes and other organs. Accurate diagnosis and reporting of such rare events are essential to clinical practice and patient care.

A Sampling of Highlights from the Literature: Article Recommendations from Our Deputy and Senior Editors.

TIM-3 blockade leads to increased DNA sensing by cGAS–STING (by Kissiovd via Wikimedia Commons)TIM-3 blocking antibodies, which are showing promise in cancer clinical trials, can reverse T-cell exhaustion, but their effects on other immune cells are less clear. de Mingo Pulido et al. show that blocking TIM-3 promotes HMGB1-dependent endocytosis of extracellular DNA by classical dendritic cells. This activates the cyclic GMP-AMP synthase (cGAS) and stimulator of IFN genes (STING) pathway, leading to type I IFN and subsequently CXCL9 production. This pathway is required for the antitumor effects of TIM-3 blockade and paclitaxel in a mouse breast cancer model. The study provides new understanding of the mechanisms underlying TIM-3–targeted therapy.de Mingo Pulido Á, …, Ruffell B. Immunity 2021 Jun 8;54:1154–67.e7.TRMs in the lungs provide a niche that promotes tumor progression (from Nephron via Wikimedia Commons)Increased understanding of the diversity of macrophages in tumors is needed to effectively target the cells therapeutically. Using single-cell RNA sequencing, Casanova-Acebes et al. find four myeloid populations in human non–small cell lung carcinoma and in a mouse model of lung adenocarcinoma. The tissue-resident macrophage (TRM) population is reduced in mouse and human tumors compared with normal lung tissues. TRMs accumulate close to tumor cells early in tumor formation, promoting epithelial–mesenchymal transition, tumor-cell invasiveness, and regulatory T-cell responses. The data identify TRMs as potential targets for preventing and treating early-stage lung cancer.Casanova-Acebes M, …, Merad M. Nature 2021 Jun 16. DOI: 10.1038/s41586-021-03651-8.CD8+ TIL function is impaired by uptake of oxidized lipids via CD36 (from Victor A. Drover via Wikipedia)Lipid accumulation is a common metabolic characteristic of the tumor microenvironment (TME). Xu et al. show that oxidized lipids are prevalent in the TME in two mouse tumor models. Oxidized lipids are taken up by CD8+ tumor-infiltrating lymphocytes (TIL) via CD36, which is expressed at elevated levels on terminally exhausted PD-1+TIM-3+CD8+ TILs. Uptake of oxidized lipids induces lipid peroxidation and p38 MAPK activation, which reduces IFNγ and TNF production. Ablation of Cd36 and overexpression of glutathione peroxidase 4 (GPX4), which suppresses lipid peroxidation, restore CD8+ TIL function, highlighting the potential for targeting this pathway for cancer immunotherapy.Xu S, …, Kaech SM. Immunity 2021 Jul 13;54:1561–77.e7.ILC2s are a new potential therapeutic target in melanoma (by Julio C. Valencia, NCI Center for Cancer Research)Group 2 innate lymphoid cells (ILC2) in the skin can have both protumorigenic and antitumorigenic properties, but their effects in the melanoma tumor microenvironment (TME) are not well-known. Jacquelot et al. show that ILC2s infiltrate melanomas and are associated with a favorable prognosis in patients. In mouse models, ILC2-derived GM-CSF recruits eosinophils into the TME, boosting antitumor responses. However, infiltrating ILC2s also express PD-1, contributing to immunosuppression. Blockade of PD-1 in combination with IL33, an activating cytokine, unleashes ILC2/eosinophil antitumor immunity in the TME. The data highlight the potential to target ILC2s in melanoma to improve antitumor responses.Jacquelot N, …, Belz GT. Nat Immunol 2021 Jul 1;22:851–64.The liver microenvironment can switch on and off dormant tumor cells (by Firstfreddy via Wikimedia Commons)How disseminated tumor cells “turn on” after dormancy to seed metastases remains unclear. Correia et al. demonstrate a key role for NK cells in preventing breast tumor cells from exiting dormancy and forming metastases in the liver. Administration of IL15 maintains IFNγ in the microenvironment and is required for keeping tumor cells in a dormant state. A reduction in NK cells in the liver, as well as a concurrent accumulation of activated hepatic stellate cells (HSC), precedes tumor-cell exit from dormancy. This process is mediated by HSC-derived CXCL12, which induces NK-cell quiescence through interactions with CXCR4. The study provides insight into how tissue environments can permit or prevent progression of metastases.Correia AL, …, Bentires-Alj M. Nature 2021 Jun 2;594:566–71.Tregs in the TME can self-regulate via a feedback loop (photo by A. Benavides)How regulatory T cells (Treg) are regulated in the tumor microenvironment (TME) is not fully understood. Marangoni et al. find that conventional dendritic cells (cDC) in the TME can present tumor-associated antigens to pre-enriched polyclonal Tregs. These Tregs are maintained in the TME via transient T-cell receptor signals received during short-lived, unstable interactions with cDCs, a process maintained by a CTLA-4–dependent feedback loop that regulates Treg activation and proliferation via CD28. Blockade of CTLA-4 stabilizes Treg–cDC interactions, promoting Treg expansion. The data highlight that further intervention may be needed during immune checkpoint blockade of CTLA-4 so that immune-suppressive cell types are not promoted.Marangoni F, …, Mempel TR. Cell 2021 Jun 21. DOI: 10.1016/j.cell.2021.05.027.

Randomized phase II trial of durvalumab (anti-PDL1) and tremelimumab (anti-CTLA4) administered in combination versus sequentially for the treatment of recurrent platinum-resistant non-clear cell ovarian cancer (NCT03026062)

<h3>Objectives:</h3> Single agent immune checkpoint blockade (ICB) has demonstrated response rates of 5-15% in patients with recurrent high-grade ovarian cancer (HGOC), with another 15-40% of patients achieving stable disease. Combination ICB using ipilimumab and nivolumab resulted in improved response rates in a mixed population with platinum resistant and sensitive disease. The objective of the current trial was to evaluate sequential versus combination CTLA4 and PDL1 blockade strategies for extending progression free survival (PFS) in patients with platinum resistant/refractory HGOC. <h3>Methods:</h3> Patients were required to have pathologically confirmed platinum resistant or refractory epithelial ovarian cancer, no prior immunotherapy, and PS=0-1 for enrollment. The current abstract includes data only on subjects with high grade serous ovarian cancer (HGSOC), as enrollment of patients with clear cell histology is still ongoing. The primary endpoint was PFS and response was assessed using modified RECIST v1.1. Unlimited numbers of prior regimens were allowed. Patients were adaptively randomized to sequential arm: tremelimumab (3mg/kg q4 weeks x 4 doses) followed by durvalumab (1.5g IV q4 weeks for up to 9 doses) upon progression, or the combination arm: tremelimumab (1mg/kg IV plus durvalumab 1.5g IV q4wk for up to 4 doses followed by durvalumab monotherapy for up to 9 doses). For the Bayesian adaptive randomization, the probability of being assigned to an arm was proportional to the likelihood the arm had better PFS, such that patients were more likely to be randomized to the more effective arm. <h3>Results:</h3> A total of 61 subjects were adaptively randomized to sequential treatment (n=38) or combination therapy (n=23). 46 (79%) patients had wild-type breast cancer gene (<i>BRCA</i>). Median prior lines of therapy was 4 (range: 1-10). There was no difference in median PFS in the sequential arm (1.84 months; 95% CI: 1.77 – 2.17)) compared with the combination arm (1.87 months; 95% CI: 1.77 – 2.43), p=0.402. Similarly, median OS in the sequential and combination arms were 10.61 months (5.95 – 15.34) and 7.26 (4.24 – 15.57), respectively (p=0.810). In the sequential arm no objective responses were observed, although 12 patients (31.6%) exhibited stable disease. In the combination arm, 2 patients had partial response (8.7%) while one additional patient (4.4%) had stable disease. The adverse event profile was consistent with that previously reported for immune checkpoint therapy. <h3>Conclusions:</h3> There was no difference in the median PFS between the combination and sequential durvalumab plus tremelimumab treatment strategy arms in a heavily pretreated population of patients with platinum resistant/refractory HGOC. Response rates were comparable to prior reports, though the combination regimen did not add significant benefit as has been previously described with combination of ipilimumab/nivolumab. Further exploration into subpopulations that may have increased benefit from ICB is warranted.

Gut microbiota signatures are associated with toxicity to combined CTLA-4 and PD-1 blockade.

Treatment with combined immune checkpoint blockade (CICB) targeting CTLA-4 and PD-1 is associated with clinical benefit across tumor types, but also a high rate of immune-related adverse events. Insights into biomarkers and mechanisms of response and toxicity to CICB are needed. To address this, we profiled the blood, tumor and gut microbiome of 77 patients with advanced melanoma treated with CICB, with a high rate of any ≥grade 3 immune-related adverse events (49%) with parallel studies in pre-clinical models. Tumor-associated immune and genomic biomarkers of response to CICB were similar to those identified for ICB monotherapy, and toxicity from CICB was associated with a more diverse peripheral T-cell repertoire. Profiling of gut microbiota demonstrated a significantly higher abundance of Bacteroides intestinalis in patients with toxicity, with upregulation of mucosal IL-1β in patient samples of colitis and in pre-clinical models. Together, these data offer potential new therapeutic angles for targeting toxicity to CICB.

Cutaneous adverse events associated with immune checkpoint blockade: A systematic review and meta-analysis.

Dermatological toxicity is the most common immune-related adverse events (irAEs) following immune checkpoint inhibitors (ICIs). A better understanding of this side effect enables early recognition, diagnosis and management in clinical practice. We did a systematic review and meta-analysis of literature published on ClinicalTrials.gov, Pubmed, Embase, and Cochrane Library to assess the differences in cutaneous irAEs among ICIs, the effect from dosage and combined treatment on the incidence, and the predictive values for prognosis. A total of 46 eligible RCTs involving 28,569 patients were included. This study indicates that cutaneous irAEs are dose-independent and agent-specific immune reactions with the highest risk observed in CTLA-4 blockade and might not a surrogate prognostic indicator.

Abstract 1568: A2aR inhibition enhances the antitumor activity of CTLA4 blockade in mouse Pten-deficient prostate cancer

Abstract Extracellular adenosine impairs immune function in tumors and limits the efficacy of anti-CTAL4 immune checkpoint blockade. We previously showed that adenosine 2A receptor (A2aR) blockade with AZD4635 moderately inhibited tumor growth, in part by improving antigen presentation and cytotoxic T cell (CTL) activity in mouse Pten-deficient prostate cancer. Here, we continue to investigate the antitumor activity of AZD4635 and its effects when combined with CTLA4 blockade (aCTLA4) in preclinical models of Pten-deficient prostate cancer. Prostate tumors from Pten conditional knockout (KO) mice treated with aCTLA4 for five days had increased expression levels of adenosinergic genes. Furthermore, gene expression, flow cytometric and IHC analyses showed increased T regulatory cell differentiation and accumulation that was offset with the addition of AZD4635. Moreover, expression levels of genes associated with Th 1 cell differentiation and T cell-mediated cytotoxicity were increased in AZD4635/aCTLA4 treated tumors. Adding AZD4635 to a four-week regimen of aCTLA4 therapy improved the antitumor response by two-fold in an early-stage intervention model of Pten-deficient prostate cancer. Androgen deprivation (AD) has the potential to promote T cell infiltration in prostate tumors and using the AZD4635/aCTLA4 treatment combination as neoadjuvant therapy to AD via surgical castration led to a greater antitumor response. The antitumor activity of this treatment combination was further examined and confirmed in a subcutaneous syngeneic genome-derived allograft model using tumor-bearing conditional Pten-deficient knockout mice grafted with Pten-deficient CRPC tumor fragments. In a Pten/Trp53 conditional double knockout (DKO) mouse model of advanced prostate cancer, the AZD4635/aCTLA4 treatment combination did not improve overall survival rates. However, when AZD4635/aCTLA4 was used as neoadjuvant therapy to AR inhibition with the anti-androgen apalutamide, it improved median survival time from 21 days in monotherapy treated mice to 34 days in AZD4635/aCTLA4 treated mice. These results provide preclinical evidence to support the rational combination of A2AR blockade with AZD4635 and aCTLA4 immune checkpoint inhibition for PTEN-deficient prostate cancer. Citation Format: Marco A. De Velasco, Yurie Kura, Noriko Sako, Naomi Ando, Kazuko Sakai, Alwin Schuller, Kazutoshi Fujita, Masahiro Nozawa, Kazuhiro Yoshimura, Kazuto Nishio, Hirotsugu Uemura. A2aR inhibition enhances the antitumor activity of CTLA4 blockade in mouse Pten-deficient prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1568.

Chemoradiation triggers antitumor Th1 and tissue resident memory-polarized immune responses to improve immune checkpoint inhibitors therapy

BackgroundMultiple synergistic combination approaches with cancer drugs are developed to overcome primary resistance to immunotherapy; however, the mechanistic rationale to combine chemoradiotherapy (CRT) with immune checkpoint inhibitors remains elusive.MethodsThis study...

Leveraging Big Data of Immune Checkpoint Blockade Response Identifies Novel Potential Targets

We here report a large-scale comparative meta-analysis of genomics and gene expression signatures of immune checkpoint blockade (ICB) responses in over 3,500 patients across 12 tumor types. Non-synonymous tumor mutational burden (nsTMB), as well as 22 out of 39 reported gene expression signatures, were significantly associated with pan-cancer ICB responses. Strikingly, the predictive value of a de novo gene expression signature (PredictIO_100), composed of the top 100 genes most significantly associated with ICB responses at pan-cancer level, was superior to nsTMB and other gene expression signatures. Two genes within PredictIO_100, F2RL1 (encoding protease-activated receptor-2) and RBFOX2 (encoding RNA binding motif protein 9), were concurrently associated with worse ICB clinical outcomes, T cell dysfunction in ICB-naive patients and resistance to dual PD-1/CTLA-4 blockade in preclinical models. Our study underlines the relative impact of candidate biomarkers of ICB responses and identifies F2RL1 and RBFOX2 as potential therapeutic targets to overcome ICB resistance.

Post-Transplant Cyclophosphamide Improves Progression Free Survival after Allogeneic Hematopoietic Stem Cell Transplantation in AML/MDS Patients with Prior CTLA-4 or PD-1 Blockade

Checkpoint inhibitors, anti-PD-1 and anti-CTLA-4 monoclonal antibodies are being increasingly used with encouraging results in patients (pts) with AML and MDS. The recipients of these agents may become candidates for allogeneic stem cell transplantation (SCT). However, a relatively high rate of grade III-IV acute graft versus host disease (GvHD) has been reported in lymphoma pts with prior PD-1 and CTLA-4 blockade using standard GvHD prophylaxis. We retrospectively analyzed 18 AML and 6 MDS pts treated with an anti-PD-1 (nivolumab) or anti-CTLA-4 antibody (ipilimumab) at some point prior to SCT at our institution over the last 3 years, and examined the impact of GvHD prophylaxis regimen on the outcome. Median age was 55 years; 22 (85%) were treated with PD-1 blockade prior to SCT (10 in combination with azacitidine and 12 with idarubicin + cytarabine), and 4 with CTLA-4 blockade (3 in combination with azacitidine and 1 alone). The number of treatment cycles were GvHD prophylaxis was either post-transplant cyclophosphamide in addition to tacrolimus and +/- mycophenolate mofetil (post-Cy group) or tacrolimus and methotrexate/mycophenolate mofetil (no post-Cy group). The post-Cy group included 3 matched unrelated (MUD), 3 matched related (MRD) and 4 haploidentical donors while the no post-Cy group had 12 MUDs, 2 MRD and 2 cord blood recipients. Disease and transplant characteristic were comparable between the two groups with the exception that more pts with post-Cy had ≥4 cycles of PD-1 or CTLA-4 blockade prior to SCT (60% vs. 25%, p=0.09), and a longer than 60 day interval between checkpoint inhibitor therapy and SCT (70% vs. 25%, p=0.03). Median follow-up of survivors was 4.5 months (range, 0.5-18). There were 2 primary graft failure with an incidence of 8%. The incidences of grades II-IV and III-IV acute GvHD (aGvHD) at day 100 were 48% and 20% respectively in the whole cohort. The number of treatment cycles with PD-1 and CTLA-4 antibody prior to SCT and the time interval from last checkpoint antibody therapy to SCT did not have an impact on the rate of aGvHD. The use of post-Cy as GvHD prophylaxis (14% vs. 60%, p=0.1) decreased while the use of MUD increased (69% vs 0%, p=0.01) the incidence of grade II-IV aGvHD by day 100. However, there was a significant negative association between the use MUD and post-Cy as GvHD prophylaxis as few pts with MUD received post-Cy compared with the rest of the study cohort (20% vs. 64%, p=0.02). Despite this, there was still a trend of lower incidence of grade II-IV aGvHD by day 100 among MUD recipients with post-Cy compared with no post-Cy (33% vs. 75%, HR=0.4, p=0.3). Other transplant outcomes of interest were also improved in post-Cy group compared with no post-Cy group (Table 1). Progression free survival was 100% in pts with post-Cy compared with 63% in no post-Cy (p=0.05) (Figure 1). No deaths were observed in post-Cy group and causes of death were disease progression in 3, aGvHD in one, infection in two, graft rejection in one patient who had no post-Cy as GVHD prophylaxis. Despite the increased rate of aGvHD; MUD recipients had comparable outcomes of PFS (64% vs. 67%, p=0.7), transplant-related mortality (15% vs. 21%, p=0.5) and overall survival (70% vs. 67%, p=0.4) compared with the rest of the cohort. In conclusion, SCT after PD-1 or CTLA-4 blockade appears feasible. Our results indicate 1) a high rate of grade III-IV aGvHD in MUD recipients who did not receive post-Cy and 2) improved PFS with the use of post-Cy independent of the donor type after the use of PD-1 or CTLA-4 blockade. The use of post-Cy as the GvHD prophylaxis deserves further investigation to improve the tolerability of SCT after the use PD-1 or CTLA-4 blockade. Disclosures Oran: AROG: Research Funding; Celgene: Research Funding; Astex: Research Funding. Jabbour: Bristol-Myers Squibb: Consultancy. DiNardo: Novartis: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Agios: Honoraria, Research Funding. Sharma: Jounce: Consultancy, Other: stock, Patents & Royalties: Patent licensed to Jounce; Astellas: Consultancy; EMD Serono: Consultancy; Amgen: Consultancy; Astra Zeneca: Consultancy; GSK: Consultancy; Consetellation: Other: stock; Evelo: Consultancy, Other: stock; Neon: Consultancy, Other: stock; Kite Pharma: Consultancy, Other: stock; BMS: Consultancy. Kantarjian: ARIAD: Research Funding; Amgen: Research Funding; Pfizer: Research Funding; Delta-Fly Pharma: Research Funding; Bristol-Meyers Squibb: Research Funding; Novartis: Research Funding. Daver: Jazz: Consultancy; Pfizer Inc.: Consultancy, Research Funding; Daiichi-Sankyo: Research Funding; Kiromic: Research Funding; Otsuka America Pharmaceutical, Inc.: Consultancy; Incyte Corporation: Honoraria, Research Funding; Karyopharm: Consultancy, Research Funding; Bristol-Myers Squibb Company: Consultancy, Research Funding; Novartis Pharmaceuticals Corporation: Consultancy; Sunesis Pharmaceuticals, Inc.: Consultancy, Research Funding; Immunogen: Research Funding.

Explant Modeling of the Immune Environment of Head and Neck Cancer.

Patients exhibit distinct responses to immunotherapies that are thought to be linked to their tumor immune environment. However, wide variations in outcomes are also observed in patients with matched baseline tumor environments, indicating that the biological response to treatment is not currently predictable using a snapshot analysis. To investigate the relationship between the immune environment of tumors and the biological response to immunotherapies, we characterized four murine head and neck squamous cell carcinoma (HNSCC) models on two genetic backgrounds. Using tumor explants from those models, we identified correlations between the composition of infiltrating immune cells and baseline cytokine profiles prior to treatment. Following treatment with PD-1 blockade, CTLA-4 blockade, or OX40 stimulation, we observed inter-individual variability in the response to therapy between genetically identical animals bearing the same tumor. These distinct biological responses to treatment were not linked to the initial tumor immune environment, meaning that outcome would not be predictable from a baseline analysis of the tumor infiltrates. We similarly performed the explant assay on patient HNSCC tumors and found significant variability between the baseline environment of the tumors and their response to therapy. We propose that tumor explants provide a rapid biological assay to assess response to candidate immunotherapies that may allow matching therapies to individual patient tumors. Further development of explant approaches may allow screening and monitoring of treatment responses in HNSCC.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Romidepsin (HDACi) plus cisplatin and nivolumab triplet combination in patients with metastatic triple negative breast cancer (mTNBC).

1076 Background: Histone deacetylase inhibitors (HDACi) upregulate genes involved in antigen presentation machinery and increase expression of natural killer group 2, member D ligands (NKG2DL), thus resulting in enhanced tumor cell recognition and response to PD-1/CTLA-4 blockade. Cisplatin and HDACi combination synergistically induces cytotoxicity, apoptosis, and DNA damage. This phase I-II trial investigated combination of romidepsin (HDACi) plus cisplatin and nivolumab (PD-1 inhibitor) in mTNBC. Patients and Methods: Eligible patients had mTNBC with any number of prior chemotherapies. Phase I was 3+3 dose-escalation design with three dose levels of romidepsin (8, 10, 12mg/m2, D2, 9) plus cisplatin 75mg/m2 D 1 every 21 days. Phase II treatment included romidepsin plus cisplatin plus nivolumab 360mg every 21 days and was designed according to Simon’s two stage minimax design. Primary endpoints were recommended phase 2 dose (RP2D) and objective response rate (ORR). Additional endpoints included safety, PFS, and pharmacokinetics. Results: 51 patients were enrolled (N=13 phase I, N=38 phase II) between 2015-2020. 69% had received ≥1 prior metastatic chemotherapy, 47% had prior platinum, 53% had liver metastasis, 12% had BRCA1/2 mutation, and 11% had PD-L1 positive disease. There were no dose limiting toxicities in phase I. The RP2D was romidepsin 12mg/m2 D2,9 + cisplatin 75mg/m2 D1 + nivolumab 360mg D1 every 21 days. Thrombocytopenia (G3:27%, G4:0%), neutropenia (G3:25%, G4:0%), anemia (G3:22%, G4:0%), nausea (G3:22%, G4:0%), and vomiting (G3:20%, G4:0%) were the most common grade 3/4 adverse events. 21% of patients had immune AEs (G3-4:8%). Among 34 evaluable phase II patients, ORR was 44% (Table), median PFS was 4.4 months, and 1-year PFS was 23%. Median OS was 10.3 months and 1-year OS was 43%. No pharmacokinetic interactions were detected with co-administration of romidepsin-cisplatin-nivolumab. Conclusions: The triplet combination of romidepsin plus cisplatin and nivolumab was well tolerated and shows encouraging efficacy in pretreated mTNBC, including in patients with PD-L1 negative disease and in those with liver metastasis. Correlative biomarker work is ongoing. This combination warrants further evaluation in larger studies. Clinical trial information: NCT02393794 .[Table: see text]

Impact of pharmacodynamic biomarkers in immuno-oncology (IO) phase 1 clinical trials.

2653 Background: Pharmacodynamic biomarkers (PD) are considered fundamental for go/no-go decisions in phase 1 trials. Despite an increase in the availability of blood-based biomarker assays, the requirement of invasive non-diagnostic research tumor biopsies for trial eligibility remains common. In the immuno-oncology (IO) era, the impact of PD analysis for the confirmation of biologic activity and recommended phase 2 dose (RP2D) has not been investigated. Methods: Phase 1 studies from 01/2014 to 12/2018 were reviewed. Among 12053 abstracts screened, a total of 143 phase I-IO trials were identified. Characteristics of studies that included on-treatment PD biomarkers (tissue-derived, blood-based and radiomic) were extracted and analyzed. Outcomes from the biomarker data in terms of proof of mechanism/biologic activity and statistically significant correlation with clinical benefit (objective response or survival) were collected. Authors’ statements on the influence of PD results on RP2D were also noted. Results: Out of 143 phase 1 IO trials, 107 (75%) were monotherapy. The most frequent IO evaluated were vaccines (41%), cell therapy (16%), immunomodulators (13%) and cytokines (7%). Of the 36 combination studies, 20 (61%) included a second IO drug while 16 (39%) included molecular-targeted agents. Only 18 of 143 studies (12%) did not report any PD data. Of the remaining 125 studies, tissue-derived PD (t-PD) biomarkers alone, blood-based PD (b-PD) biomarkers alone, both t-PD and b-PD biomarkers, and imaging biomarkers were tested in 3 (2%), 97 (78%), 25 (20%), and 7 (6%), respectively. Demonstration of proof of mechanism/biologic activity only were reported in 16/28 (57%), 80/122 (66%) and 4/7 (57%) of the t-PD, b-PD and imaging biomarker studies, respectively. Significant correlation with clinical benefit was reported in 2/28 (7%), 7/122 (6%) and 0/7 (0%) of the t-PD, b-PD and imaging biomarker studies, respectively; these involved 4 vaccines (1 in combination with PD1 blockade), 1 cell therapy and 1 oncolytic virus (in combination with CTLA4 blockade). Among 35 b-PD studies with negative results, 5 also performed t-PD biomarkers, all with negative results. Notably, 3 out of 10 t-PD studies with negative results reported concurrent positive b-PD results. Based on the published reports, authors stated that biomarker results helped with RP2D determination in 16/28 (57%) of t-PD and 78/122 (64%) of b-PD studies. Conclusions: Our results suggest that in the IO era, most studies perform PD analysis, with similar proportions of t-PD and b-PD showing proof of mechanism/biologic activity. IO PD biomarkers have limited correlation with clinical benefit. Many authors considered IO PD biomarkers to be relevant in RP2D decisions, but this needs confirmation by other measures of impact. With continued technological developments utilizing circulating biomarkers, b-PD may ultimately replace many t-PD tests in future IO studies.

Somatic mutations predict immune-related adverse events (irAEs) and survival following CTLA4 blockade in melanoma patients.

e21584 Background: Predicting immune-related adverse events (irAEs) resulting from immune checkpoint inhibitors (ICIs) as well as the likelihood of clinical benefit is an area of great interest. irAEs have been associated with clinical outcome measures and we were interested in examining somatic mutations that may correlate with irAEs and subsequently with relapse free survival (RFS) and overall survival (OS). Methods: Our irAEs of interest for this analysis were rash and colitis based on prior data and these were tested for association with RFS and overall OS. Nonsynonymous somatic mutations were identified utilizing tumor and matched blood samples from 22 metastatic melanoma patients treated with neoadjuvant ipilimumab. Whole exome sequencing was performed using the SOLiD 5500 Next-Generation Sequencing platform. Somatic mutations were identified by subtraction of germline variants. Total mutational burden was assessed, and individual mutations were correlated with irAEs and with clinical outcome. Results: MUC16 was the most commonly mutated gene (82%). Of notable known oncogenic mutations, BRAF was the most common (50%) followed by NRAS (23%). Among known oncogenic signaling pathways, enrichment was most common in RTK-RAS (58%), followed by NOTCH and WNT. Development of colitis showed a strong trend in association with RFS. Development of rash indicated a similar trend. 20 different statistically significant mutations (p &lt; 0.05) were identified among patients with colitis and these were also associated with OS and RFS. Notably, PTPRO mutation status (known to antagonize PDL1 expression) appeared protective against colitis and associated with worse RFS and OS. Similarly, ADGB mutation was significantly associated with developing rash and also associated with improved RFS and OS. Correcting for TMB in a multivariate model confirmed the associations. Conclusions: Somatic mutations were found to be associated with the irAEs of rash and colitis and with clinical outcome following ipilimumab treatment of melanoma. Our findings warrant further investigation and validation in independent cohorts.