Rational Selection of Syngeneic Preclinical Tumor Models for Immunotherapeutic Drug Discovery

Murine syngeneic tumor models are critical to novel immuno-based therapy development, but the molecular and immunologic features of these models are still not clearly defined. The translational relevance of differences between the models is not fully understood, impeding appropriate preclinical model selection for target validation, and ultimately hindering drug development. Across a panel of commonly used murine syngeneic tumor models, we showed variable responsiveness to immunotherapies. We used array comparative genomic hybridization, whole-exome sequencing, exon microarray analysis, and flow cytometry to extensively characterize these models, which revealed striking differences that may underlie these contrasting response profiles. We identified strong differential gene expression in immune-related pathways and changes in immune cell-specific genes that suggested differences in tumor immune infiltrates between models. Further investigation using flow cytometry showed differences in both the composition and magnitude of the tumor immune infiltrates, identifying models that harbor "inflamed" and "non-inflamed" tumor immune infiltrate phenotypes. We also found that immunosuppressive cell types predominated in syngeneic mouse tumor models that did not respond to immune-checkpoint blockade, whereas cytotoxic effector immune cells were enriched in responsive models. A cytotoxic cell-rich tumor immune infiltrate has been correlated with increased efficacy of immunotherapies in the clinic, and these differences could underlie the varying response profiles to immunotherapy between the syngeneic models. This characterization highlighted the importance of extensive profiling and will enable investigators to select appropriate models to interrogate the activity of immunotherapies as well as combinations with targeted therapies in vivo Cancer Immunol Res; 5(1); 29-41. ©2016 AACR.

Comparative study of immune regulatory properties of stem cells derived from different tissues

Allogeneic stem cell (SC)-based therapy is a promising tool for the treatment of a range of human degenerative and inflammatory diseases. Many reports highlighted the immune modulatory properties of some SC types, such as mesenchymal stromal cells (MSCs), but a comparative study with SCs of different origin, to assess whether immune regulation is a general SC property, is still lacking. To this aim, we applied highly standardized methods employed for MSC characterization to compare the immunological properties of bone marrow-MSCs, olfactory ectomesenchymal SCs, leptomeningeal SCs, and three different c-Kit-positive SC types, that is, amniotic fluid SCs, cardiac SCs, and lung SCs. We found that all the analyzed human SCs share a common pattern of immunological features, in terms of expression of activation markers ICAM-1, VCAM-1, HLA-ABC, and HLA-DR, modulatory activity toward purified T, B, and NK cells, lower immunogenicity of inflammatory-primed SCs as compared to resting SCs, and indoleamine-2,3-dioxygenase-activation as molecular inhibitory pathways, with some SC type-related peculiarities. Moreover, the SC types analyzed exert an anti-apoptotic effect toward not-activated immune effector cells (IECs). In addition, we found that the inhibitory behavior is not a constitutive property of SCs, but is acquired as a consequence of IEC activation, as previously described for MSCs. Thus, immune regulation is a general property of SCs and the characterization of this phenomenon may be useful for a proper therapeutic use of SCs.

Clinical-grade mesenchymal stromal cells produced under various good manufacturing practice processes differ in their immunomodulatory properties: standardization of immune quality controls

Clinical-grade mesenchymal stromal cells (MSCs) are usually expanded from bone marrow (BMMSCs) or adipose tissue (ADSCs) using processes mainly differing in the use of fetal calf serum (FCS) or human platelet lysate (PL). We aimed to compare immune modulatory properties of clinical-grade MSCs using a combination of fully standardized in vitro assays. BMMSCs expanded with FCS (BMMSC-FCS) or PL (BMMSC-PL), and ADSC-PL were analyzed in quantitative phenotypic and functional experiments, including their capacity to inhibit the proliferation of T, B, and NK cells. The molecular mechanisms supporting T-cell inhibition were investigated. These parameters were also evaluated after pre-stimulation of MSCs with inflammatory cytokines. BMMSC-FCS, BMMSC-PL, and ADSC-PL displayed significant differences in expression of immunosuppressive and adhesion molecules. Standardized functional assays revealed that resting MSCs inhibited proliferation of T and NK cells, but not B cells. ADSC-PL were the most potent in inhibiting T-cell growth, a property ascribed to interferon-γ-dependent indoleamine 2,3-dioxygenase activity. MSCs did not stimulate allogeneic T cell proliferation but were efficiently lysed by activated NK cells. The systematic use of quantitative and reproducible validation techniques highlights differences in immunological properties of MSCs produced using various clinical-grade processes. ADSC-PL emerge as a promising candidate for future clinical trials.

Adipose-derived stromal cells (ASCs)

Adipose-derived stromal cells (ASCs) are now emerging as a good alternative to bone marrow derived mesenchymal stromal cells (BM-MSC) for cellular therapy. Similarly to BM-MSC, ASCs can be easily isolated as adherent fibroblastoid cell population after processing lipoaspirate samples. Lipoaspiration provides a great number of cells, without extensive manipulation. ASCs express classical mesenchymal markers and only at early passages express CD34. ASCs can differentiate in cells of mesodermal lineages, such as adipocytes, osteocytes and condrocytes. ASCs share with BM-MSC the same ability to inhibit the proliferation of allogeneic, activated immune cells, thus affecting in vivo in animal models the onset and course of rheumatoid arthritis (RA), experimental autoimmune encephalomyelitis (EAE), Crohn's disease (CD), ulcerous colitis (UC) and graft-versus-host disease (GvHD). On the other hand, the main molecular pathway involved in this effect is still unclear. On the basis of this functional property, ASCs are used in different clinical trials to treat RA, CD, UC and GvHD. However, the most promising field of clinical application is represented by bone defect repair. Despite the ability to regenerate injured tissues and to block the progression of inflammatory disorders, some authors reported that ASCs can also induce, in in vivo animal models, the growth and vascularization of solid and hematological tumors. Conversely, ASCs have been shown to hamper tumor cell proliferation, reduce cell viability and induce necrosis. Thus, more accurate studies, collaborative protocols, high standardization of methods, and safety controls are required to exclude transformation of transplanted ASCs.

Immunological properties of embryonic and adult stem cells

The possibility of treating degenerative diseases by stem cell-based approaches is a promising therapeutical option. Among major concerns for the clinical application of stem cells, some derive from the possibility that stem cells may be rejected by the immune system as a consequence of histoincompatibility and that stem cells themselves may interfere with the normal functions of host immune response. Therefore, the immunogenicity and the immunomodulatory properties of stem cells must be carefully addressed. Although these properties are common features of different stem cell types, some peculiarities can be recognized and characterized for their proper clinical use.

Serratus fascia "sandwich" free-tissue transfer for complex dorsal hand and wrist avulsion injuries

The serratus anterior fascia was used as a free-tissue transfer in four patients for the reconstruction of dorsal hand defects. All patients had multiple open metacarpal fractures with extensor tendon injuries. The fascia was used to "sandwich" the extensor tendons in a bed of areolar gliding tissue to avoid adhesions. The mean follow-up was 2 years. There were no complications and all flaps survived completely. All flaps were grafted with meshed split-thickness skin at the time of transfer with a 100 percent take in all cases. A good functional result was noted in all patients. This free-tissue transfer is recommended for complex injuries to the dorsum of the hand associated with soft-tissue defects.

Evaluation of sorivudine (BV-araU) versus acyclovir in the treatment of acute localized herpes zoster in human immunodeficiency virus-infected adults. The Multinational Sorivudine Study Group

The clinical efficacy and safety of sorivudine as treatment for acute cutaneous zoster in human immunodeficiency virus-infected adults was compared with that of acyclovir in a double-blinded randomized study. A total of 125 patients with laboratory-confirmed zoster rash present for < or =72 h were assigned treatment with either 40 mg of sorivudine once daily or 800 mg of acyclovir five times daily, both taken orally for 7 days. Patients were assessed daily until all lesions crusted and then monthly for 6 months for postherpetic neuralgia (PHN) and for 12 months for recurrent or new episodes of zoster. Sorivudine significantly shortened the median period of new vesicle formation from 3.0 to 4.0 days (log rank P = .0001). Sorivudine was effective regardless of duration of rash before treatment. Zoster recurrences and new episodes were experienced by fewer patients assigned sorivudine (11%) than acyclovir (26%, P = .037). No differences were seen in incidence, severity, or duration of either acute neuritis or PHN. Both treatments were well tolerated.

Serum interleukin-6 in acute pancreatitis due to common bile duct stones. A reliable marker of necrosis

In a prospective clinical study we have assessed the value of serum interleukin-6 in comparison with C-reactive protein in discriminating necrotizing from oedematous acute pancreatitis due to common bile duct stones in the first hours of disease. The study comprised 36 patients with acute biliary pancreatitis; inclusion criteria were admission in hospital within 48 hours from the onset of symptoms, availability of contrast enhanced CT scan within 72 hours from admission and presence of common bile duct stones at early ERCP. A sample of serum was taken at hospitalization and interleukin-6 and C-reactive protein were measured. Interleukin-6 levels were significantly higher in necrotizing pancreatitis, being closely related to the extension of necrosis. C-reactive protein showed low efficacy in detecting necrotizing forms, although its levels were higher than in oedematous. We conclude that serum interleukin-6 is a very reliable marker of necrosis in the first 48 hours of acute biliary pancreatitis.

Early prediction of aetiology and severity of acute pancreatitis by serum amylase and lipase assays

OBJECTIVE

To evaluate whether simple pancreatic enzyme assays are useful in the early assessment of aetiology and prognosis of acute pancreatitis.

DESIGN

A retrospective clinical study.

SETTING

Department of Internal Medicine with a Pancreatic Disease Centre.

PATIENTS

The study included 246 patients with acute pancreatitis admitted to our Unit within the first 24 hours from the onset of disease. Amylase and lipase serum levels and lipase/amylase ratio were evaluated.

RESULTS

Serum amylase was higher in patients with necrotizing pancreatitis than oedematous and biliary pancreatitis than alcoholic (p < 0.009 and p < 0.05 respectively), but a high degree of overlap between values was found. No differences were noted in lipase serum levels. Lipase/amylase ratio was not different between patients with alcoholic and nonalcoholic pancreatitis.

CONCLUSIONS

Evaluation of serum amylase and lipase is not useful for assessing aetiology and severity of acute pancreatitis, although amylase may be higher in severe and biliary forms.

Rates and risk factors for adverse events associated with didanosine in the expanded access program

The didanosine Expanded Access Program was the largest AIDS treatment program to prospectively evaluate the safety of an antiretroviral agent among patients with advanced human immunodeficiency virus (HIV) disease in whom therapy with zidovudine was failing. A total of 21,198 patients who had infections refractory to zidovudine or who were intolerant of the drug received didanosine as a buffered powder for oral solution (sachet), with total daily doses of 6.6-10 mg/kg; the median CD4 lymphocyte count was 0.04 x 10(9)/L for this population. At the currently recommended dose (6.6-8.29 mg/[kg.d]), 6-month estimated rates of pancreatitis ranged from 1.2% for patients with AIDS-related complex (ARC) and CD4 lymphocyte counts of > or = 0.1 x 10(9)/L to 6.7% for patients with AIDS and CD4 lymphocyte counts of < 0.05 x 10(9)/L. Laboratory toxicities of World Health Organization grades 3 and 4 developed in fewer than 4% of patients entering the study with normal baseline values; the sole exception was leukopenia, which was documented in 8% of these patients. The results of this program demonstrated that patients with CD4 lymphocyte counts of < 0.10 x 10(9)/L or with a diagnosis of AIDS (defined by the 1987 classification system of the Centers for Disease Control and Prevention) were less tolerant of didanosine and significantly more likely to develop adverse clinical reactions and myelosuppression than other patients.

Soluble interleukin-2 receptor: a new marker in pancreatic adenocarcinoma?

An increase in soluble Interleukin-2 receptor has been observed in several lymphoproliferative diseases and in certain solid neoplasms. Little is known, however, of the serum levels of this marker in pancreatic cancer. We studied the behaviour of the soluble Interleukin-2 receptor in 32 patients with pancreatic cancer versus 17 patients with alcoholic chronic pancreatitis and 24 healthy controls. The results obtained showed a significant statistical difference (Student's "t"-test and Mann Whitney U test) between pancreatic cancer on one hand and chronic pancreatitis plus healthy controls on the other (p < 0.0001).