Jon Arnason

Idelalisib given front-line for treatment of chronic lymphocytic leukemia causes frequent immune-mediated hepatotoxicity

Idelalisib is a small-molecule inhibitor of PI3Kδ with demonstrated efficacy for the treatment of relapsed/refractory chronic lymphocytic leukemia (CLL). To evaluate idelalisib as front-line therapy, we enrolled 24 subjects in a phase 2 study consisting of 2 months of idelalisib monotherapy followed by 6 months of combination therapy with idelalisib and the anti-CD20 antibody ofatumumab. After a median follow-up period of 14.7 months, hepatotoxicity was found to be a frequent and often severe adverse event. A total of 19 subjects (79%) experienced either grade ≥1 ALT or AST elevation during the study, and 13 subjects (54%) experienced grade ≥3 transaminitis. The median time to development of transaminitis was 28 days, occurring before ofatumumab introduction. Younger age and mutated immunoglobulin heavy chain status were significant risk factors for the development of hepatotoxicity. Multiple lines of evidence suggest that this hepatotoxicity was immune mediated. A lymphocytic infiltrate was seen on liver biopsy specimens taken from 2 subjects with transaminitis, and levels of the proinflammatory cytokines CCL-3 and CCL-4 were higher in subjects experiencing hepatotoxicity. All cases of transaminitis resolved either by holding the drug, initiating immunosuppressants, or both, and rates of recurrent toxicity were lower in patients taking steroids when idelalisib was reinitiated. A decrease in peripheral blood regulatory T cells was seen in patients experiencing toxicity on therapy, which is consistent with an immune-mediated mechanism. These results suggest that caution should be taken as drugs within this class are developed for CLL, particularly in younger patients who have not received prior disease-specific therapy. This study was registered at www.clinicaltrials.gov as #NCT02135133.

Lenalidomide enhances anti-myeloma cellular immunity

Lenalidomide is an effective therapeutic agent for multiple myeloma that exhibits immunomodulatory properties including the activation of T and NK cells. The use of lenalidomide to reverse tumor-mediated immune suppression and amplify myeloma-specific immunity is currently being explored. In the present study, we examined the effect of lenalidomide on T-cell activation and its ability to amplify responses to a dendritic cell-based myeloma vaccine. We demonstrate that exposure to lenalidomide in the context of T-cell expansion with direct ligation of CD3/CD28 complex results in polarization toward a Th1 phenotype characterized by increased IFN-γ, but not IL-10 expression. In vitro exposure to lenalidomide resulted in decreased levels of regulatory T cells and a decrease in T-cell expression of the inhibitory marker, PD-1. Lenalidomide also enhanced T-cell proliferative responses to allogeneic DCs. Most significantly, lenalidomide treatment potentiated responses to the dendritic cell/myeloma fusion vaccine, which were characterized by increased production of inflammatory cytokines and increased cytotoxic lymphocyte-mediated lysis of autologous myeloma targets. These findings indicate that lenalidomide enhances the immunologic milieu in patients with myeloma by promoting T-cell proliferation and suppressing inhibitory factors, and thereby augmenting responses to a myeloma-specific tumor vaccine.

Individualized vaccination of AML patients in remission is associated with induction of antileukemia immunity and prolonged remissions

A personalized DC/AML fusion cell vaccine promotes the expansion of leukemia-specific T cells and prolonged remission in patients. Immune cells join leukemia then beat it Acute myeloid leukemia (AML) is an aggressive hematologic cancer. The only curative treatment available for this disease is hematopoietic stem cell transplantation, which can result in donor immune cells helping to eradicate the cancer. Unfortunately, this procedure is not always effective and is itself associated with numerous complications and risk of death. Rosenblatt et al. have identified a potentially better way to stimulate an immune response against AML by fusing patients’ own leukemia cells with dendritic cells. The resulting fusion cells were very effective at presenting tumor antigens to T cells, resulting in a strong antitumor T cell response and prolonged survival in human patients. We developed a personalized cancer vaccine in which patient-derived acute myeloid leukemia (AML) cells are fused with autologous dendritic cells, generating a hybridoma that potently stimulates broad antitumor responses. We report results obtained from the first 17 AML patients, who achieved remission after chemotherapy and were then serially vaccinated to target minimal residual disease and prevent relapse. Vaccination was well tolerated and induced inflammatory responses at the site of administration, characterized by the dense infiltration of T cells. Vaccination was also associated with a marked rise in circulating T cells recognizing whole AML cells and leukemia-specific antigens that persisted for more than 6 months. Twelve of 17 vaccinated patients (71%; 90% confidence interval, 52 to 89%) remain alive without recurrence at a median follow-up of 57 months. The results demonstrate that personalized vaccination of AML patients in remission induces the expansion of leukemia-specific T cells and may be protective against disease relapse.

MUC1 Is a Potential Target for the Treatment of Acute Myeloid Leukemia Stem Cells

Acute myeloid leukemia (AML) is a malignancy of stem cells with an unlimited capacity for self-renewal. MUC1 is a secreted, oncogenic mucin that is expressed aberrantly in AML blasts, but its potential uses to target AML stem cells have not been explored. Here, we report that MUC1 is highly expressed on AML CD34(+)/lineage(-)/CD38(-) cells as compared with their normal stem cell counterparts. MUC1 expression was not restricted to AML CD34(+) populations as similar results were obtained with leukemic cells from patients with CD34(-) disease. Engraftment of AML stem cell populations that highly express MUC1 (MUC1(high)) led to development of leukemia in NOD-SCID IL2Rgamma(null) (NSG) immunodeficient mice. In contrast, MUC1(low) cell populations established normal hematopoiesis in the NSG model. Functional blockade of the oncogenic MUC1-C subunit with the peptide inhibitor GO-203 depleted established AML in vivo, but did not affect engraftment of normal hematopoietic cells. Our results establish that MUC1 is highly expressed in AML stem cells and they define the MUC1-C subunit as a valid target for their therapeutic eradication.

Effectiveness and Safety of Tocilizumab, an Anti–Interleukin-6 Receptor Monoclonal Antibody, in a Patient With Refractory GI Graft-Versus-Host Disease

A 22-year-old white man with idiopathic, severe aplastic anemia underwent an allogeneic stem-cell transplantation from a human leukocyte antigen–matched sibling on June 4, 2008. Pretransplantation course was complicated by Klebsiella bacteremia and Clostridium difficile infection. The conditioning regimen consisted of cyclophosphamide 200 mg/kg and horse antithymocyte globulin 9 mg/kg and graft-versus-host disease (GVHD) prophylaxis with tacrolimus and methotrexate 5 mg/m on days 1, 3, 6, and 11. On day 12, 1 day before engraftment, he developed stage 3 acute cutaneous GVHD. The skin rash completely resolved after starting prednisone 1 mg/kg. On day 32, he developed abdominal pain, nausea, vomiting, and watery diarrhea with a volume of 5 to 6 L per day and a recurrence of the maculopapular skin rash. He was treated with methylprednisolon 2 mg/kg and denileukin diftitox 4.5 mg/kg on days 1 to 5 and 8 and was enrolled onto a clinical trial for acute GVHD with mesenchymal stem cells versus placebo. A duodenal biopsy was consistent with GVHD. Abdominal cramping and diarrhea volume did not improve, and he then received additional immunosuppressive agents, including infliximab 10 mg/kg two times per week then once per week for four more doses and mycophenalate mofitil 1,000 mg two times per day, sirolimus 4 mg once daily, budesonide 3 mg two times per day, and photophoresis two times per week. By day 96, the patient was producing 600 mL of stool per day and being treated with methyprednisolone 50 mg once daily; budesonide, tacrolimus, and sirolimus; inflixamab once per week; and photophoresis twice per week. He had a GVHD Activity Index of 74, which correlates with a probability of mortality of 75% at day 200. During this period, an exhaustive effort was made to rule out other causes of diarrhea, such as cytomegalovirus (CMV), noravirus, cryptosporidial, mycobacterial, and fungal infections as well as mycophenalate toxicity. Diarrhea and cramping were relatively controlled, and prednisone was slowly tapered to 30 mg once per day; tacrolimus, budesonide, and sirolimus continued to be administered. However, on day 222, the patient experienced progressive abdominal pain and diarrhea with an increase in volume to 12 L per day. Colonic biopsies were consistent with GVHD without evidence of an infectious etiology. Again, he was treated with a series of immunosuppressive agents, including rabbit thymoglobulin 3 mg/kg, dacluzimab 5 mg/kg, and photopheresis and methotrexate 10 mg once per week. Diarrhea continued at a volume of 4 to 5 L a day. On day 295, repeat duodenal biopsies demonstrated preservation of villous architecture with mild regenerative changes in the deep crypt region (Fig 1A) and numerous apoptotic epithelial cells in the deep crypts (Fig 1B, black arrows). The colonic mucosal biopsy samples showed crypt architectural distortion in the absence of increased inflammation and apoptotic epithelial cells scattered throughout the crypts; some had the exploding appearance typical of GVHD (Figs 1C, 1D [black arrows]). As a result of the intense immune suppression, he experienced CMV and Epstein-Barr virus (EBV) reactivation and proven pulmonary Aspergillosis, and he became narcotic dependent. Because of the refractoriness of the patient to all known treatments for GVHD, we requested tocilizimab (TCZ) for compassionate use after carefully considering the rare but serious adverse effects of lower GI perforation and viral reactivation that have been reported in clinical trials. Institutional review board approval and informed consent were obtained. On the basis of a regimen that had been studied in patients with Crohn’s disease, we administered TCZ 8 mg/kg every 2 weeks for eight infusions beginning on day 413. After the first infusion, the patient reported a subjective improvement in abdominal cramping, diarrhea volume, and frequency. He continued to improve after each infusion (Fig 2, course of diarrhea in response to treatment for GVHD; black arrows, the first and last dose of toclizumab; MMF, mycophenolate mofetil; MTX, methotrexate; ATG, antithymocyte globulin). In addition, he stopped requiring intravenous hydration (2 L of normal saline daily before TCZ), parenteral electrolyte supplements, as well as platelet and red cell transfusion support. CMV and EBV polymerase chain reactions remained undetectable, and pulmonary aspergillosis was resolved with oral voriconazole 200 mg two times per day. On day 499, a repeat colonic biopsy was performed, which revealed reversion of the crypt architecture to near normal and rare shrunken apoptotic epithelial cells in the colonic crypts (Figs 1E, 1F [black arrow]). The patient received his last dose of TCZ on November 5, 2009. On November 20, 2009, he presented with a complaint of nausea and vomiting for 1 day. A computed tomography scan of the abdomen was interpreted as pneumoperitoneum and pneumoretroperitoneum around the colon and duodenum suspicious for a bowel perforation. A laparoscopic exploration did not find gas in the peritoneum or peritonitis or any other evidence of perforation. He improved spontaneously in a few days, and this episode was thought to be an ileus induced by narcotic dependence, which had occurred multiple times during his extensive course of treatment. The patient continued to be free of diarrhea and abdominal cramps 8 months after the completion of one course of TCZ and was undergoing immunosuppressive maintenance with prednisone 20 mg once per day and oral mycophenolate mofetil. Furthermore, his narcotic requirements decreased by 75% of the baseline before TCZ treatment. Patients with acute GVHD unresponsive to initial treatment with high-dose glucocorticosteroids have a 40% overall response rate to second-line immunomodulatory agents. Published response rates to acute GVHD therapy with tertiary therapies are in the range of 35%, and survival rates are approximately 10% at 1 year. Preclinical studies have implicated interleukin (IL) -6 as a key mediator of the inflammation responsible for the development of GVHD. TCZ is a humanized anti–IL-6 receptor monoclonal antibody that blocks IL-6 receptor signaling and trans-signaling; it has shown remission-inducing efficacy with a well-characterized safety profile in JOURNAL OF CLINICAL ONCOLOGY D I A G N O S I S I N O N C O L O G Y VOLUME 28 NUMBER 30 OCTOBER 2

Haemophagocytic lymphohistiocytosis in adults: a multicentre case series over 7 years.

Haemophagocytic lymphohistiocytosis (HLH) is a syndrome of uncontrolled immune activation that has gained increasing attention over the past decade. Although classically known as a familial disorder of children caused by mutations that affect cytotoxic T‐cell function, an acquired form of HLH in adults is now widely recognized. This is often seen in the setting of malignancy, infection or rheumatological disorders. We performed a retrospective review across 3 tertiary care centres and identified 68 adults with HLH. The average age was 53 years (range 18–77 years) and 43 were male (63%). Underlying disorders included malignancy in 33 patients (49%), infection in 22 (33%), autoimmune disease in 19 (28%) and idiopathic HLH in 15 (22%). Patients were treated with disease‐specific therapy and immunomodulatory agents. After a median follow‐up of 32·2 months, 46 patients had died (69%). The median overall survival was 4 months (95% CI: 0·0–10·2 months). Patients with malignancy had a worse prognosis compared to those without (median survival 2·8 months versus 10·7 months, P = 0·007). HLH is a devastating disorder with a high mortality. Further research is needed to improve treatment and outcomes.

Mucin 1 is a potential therapeutic target in cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is an aggressive neoplasm with limited treatments for patients with advanced disease. The mucin 1 C-terminal subunit (MUC1-C) oncoprotein plays a critical role in regulating cell proliferation, apoptosis, and protection from cytotoxic injury mediated by reactive oxygen species (ROS). Although CTCL cells exhibit resistance to ROS-induced apoptosis, the expression and functional significance of MUC1 in CTCL have not been previously investigated. Present studies demonstrate that MUC1-C is overexpressed in CTCL cell lines and primary CTCL cells but is absent in resting T cells from healthy donors and B-cell lymphoma cells. We have developed a cell-penetrating peptide that disrupts homodimerization of the MUC1-C subunit necessary for its nuclear translocation and downstream signaling. We show that treatment of CTCL cells with the MUC1-C inhibitor is associated with downregulation of the p53-inducible regulator of glycolysis and apoptosis and decreases in reduced NAD phosphate and glutathione levels. In concert with these results, targeting MUC1-C in CTCL cells increased ROS and, in turn, induced ROS-mediated late apoptosis/necrosis. Targeting MUC1-C in CTCL tumor xenograft models demonstrated significant decreases in disease burden. These findings indicate that MUC1-C maintains redox balance in CTCL cells and is thereby a novel target for the treatment of patients with CTCL.

MUC1 inhibition leads to decrease in PD-L1 levels via upregulation of miRNAs

The PD-L1/PD-1 pathway is a critical component of the immunosuppressive tumor microenvironment in acute myeloid leukemia (AML), but little is known about its regulation. We investigated the role of the MUC1 oncoprotein in modulating PD-L1 expression in AML. Silencing of MUC1 in AML cell lines suppressed PD-L1 expression without a decrease in PD-L1 mRNA levels, suggesting a post-transcriptional mechanism of regulation. We identified the microRNAs miR-200c and miR-34a as key regulators of PD-L1 expression in AML. Silencing of MUC1 in AML cells led to a marked increase in miR-200c and miR-34a levels, without changes in precursor microRNA, suggesting that MUC1 might regulate microRNA-processing. MUC1 signaling decreased the expression of the microRNA-processing protein DICER, via the suppression of c-Jun activity. NanoString (Seattle, WA, USA) array of MUC1-silenced AML cells demonstrated an increase in the majority of probed microRNAs. In an immunocompetent murine AML model, targeting of MUC1 led to a significant increase in leukemia-specific T cells. In concert, targeting MUC1 signaling in human AML cells resulted in enhanced sensitivity to T-cell-mediated lysis. These findings suggest MUC1 is a critical regulator of PD-L1 expression via its effects on microRNA levels and represents a potential therapeutic target to enhance anti-tumor immunity.

Alemtuzumab use in relapsed and refractory chronic lymphocytic leukemia: a history and discussion of future rational use

In this review, we outline the clinical experience with single-agent alemtuzumab as a treatment for relapsed and refractory chronic lymphocytic leukemia (CLL) in both prospective and retrospective trials and describe the multiagent use of the drug with the goal of updating clinicians on recent developments and possible future rational combinations. Alemtuzumab, an antibody targeting the lymphocyte-specific surface marker CD52, is an approved agent for the treatment of CLL. Despite its demonstrated efficacy, likely secondary to concerns regarding infectious complications, it is most commonly used in the relapsed and refractory setting. Given alemtuzumab’s unique mechanism of action it has been demonstrated to have activity in disease that is refractory to both alkylating agents and purine analogs. Furthermore, it has activity in TP53-mutated disease, which has the worst prognosis of any subset of CLL. Alemtuzumab has greater efficacy on circulating disease relative to nodal disease. Rational combinations are attempting to use these attributes to increase response rates in patients with relapsed and refractory disease.

MUC1 mediated induction of myeloid-derived suppressor cells in patients with acute myeloid leukemia.

Myeloid-derived suppressor cells (MDSCs) play a critical role in promoting immune tolerance and disease growth. The mechanism by which tumor cells evoke the expansion of MDSCs in acute myeloid leukemia (AML) has not been well described. We have demonstrated that patients with AML exhibit increased presence of MDSCs in their peripheral blood, in comparison with normal controls. Cytogenetic studies demonstrated that MDSCs in patients with AML may be derived from leukemic or apparently normal progenitors. Engraftment of C57BL/6 mice with TIB-49 AML led to an expansion of CD11b+ Gr1+ MDSCs in bone marrow and spleen. Coculture of the AML cell lines MOLM-4, THP-1 or primary AML cells with donor peripheral blood mononuclear cells elicited a cell contact-dependent expansion of MDSCs. MDSCs were suppressive of autologous T-cell responses as evidenced by reduced T-cell proliferation and a switch from a Th1 to a Th2 phenotype. We hypothesized that the expansion of MDSCs in AML is accomplished by tumor-derived extracellular vesicles (EVs). Using tracking studies, we demonstrated that AML EVs are taken-up myeloid progenitor cells, resulting in the selective proliferation of MDSCs in comparison with functionally competent antigen-presenting cells. The MUC1 oncoprotein was subsequently identified as the critical driver of EV-mediated MDSC expansion. MUC1 induces increased expression of c-myc in EVs that induces proliferation in the target MDSC population via downstream effects on cell cycle proteins. Moreover, we demonstrate that the microRNA miR34a acts as the regulatory mechanism by which MUC1 drives c-myc expression in AML cells and EVs.