Novel oncolytic adenovirus expressing enhanced cross-hybrid IgGA Fc PD-L1 inhibitor activates multiple immune effector populations leading to enhanced tumor killing in vitro, in vivo and with patient-derived tumor organoids

Background

Despite the success of immune checkpoint inhibitors against PD-L1 in the clinic, only a fraction of patients benefit from such therapy. A theoretical strategy to increase efficacy would be to arm such antibodies with Fc-mediated effector mechanisms. However, these effector mechanisms are inhibited or reduced due to toxicity issues since PD-L1 is not confined to the tumor and also expressed on healthy cells. To increase efficacy while minimizing toxicity, we designed an oncolytic adenovirus that secretes a cross-hybrid Fc-fusion peptide against PD-L1 able to elicit effector mechanisms of an IgG1 and also IgA1 consequently activating neutrophils, a population neglected by IgG1, in order to combine multiple effector mechanisms.

Methods

The cross-hybrid Fc-fusion peptide comprises of an Fc with the constant domains of an IgA1 and IgG1 which is connected to a PD-1 ectodomain via a GGGS linker and was cloned into an oncolytic adenovirus. We demonstrated that the oncolytic adenovirus was able to secrete the cross-hybrid Fc-fusion peptide able to bind to PD-L1 and activate multiple immune components enhancing tumor cytotoxicity in various cancer cell lines, in vivo and ex vivo renal-cell carcinoma patient-derived organoids.

Results

Using various techniques to measure cytotoxicity, the cross-hybrid Fc-fusion peptide expressed by the oncolytic adenovirus was shown to activate Fc-effector mechanisms of an IgA1 (neutrophil activation) as well as of an IgG1 (natural killer and complement activation). The activation of multiple effector mechanism simultaneously led to significantly increased tumor killing compared with FDA-approved PD-L1 checkpoint inhibitor (Atezolizumab), IgG1-PDL1 and IgA-PDL1 in various in vitro cell lines, in vivo models and ex vivo renal cell carcinoma organoids. Moreover, in vivo data demonstrated that Ad-Cab did not require CD8+ T cells, unlike conventional checkpoint inhibitors, since it was able to activate other effector populations.

Conclusion

Arming PD-L1 checkpoint inhibitors with Fc-effector mechanisms of both an IgA1 and an IgG1 can increase efficacy while maintaining safety by limiting expression to the tumor using oncolytic adenovirus. The increase in tumor killing is mostly attributed to the activation of multiple effector populations rather than activating a single effector population leading to significantly higher tumor killing.

Abstract 1867: Characterization in patient derived tumor organoids of novel oncolytic adenoviruses expressing enhanced cross-hybrid IgGA Fc PD-L1 inhibitors

Despite the success of immune checkpoint inhibitors in the clinic, they only benefit a fraction of patients. A theoretical strategy to increase efficacy would be to enhance such antibodies with Fc-mediated effector mechanisms. Current IgG1 antibodies are excellent activators of natural killer cells yet neglect a crucial effector population, neutrophils. Hence, we designed a cross-hybrid Fc-fusion peptide against PD-L1 able to elicit simultaneously effector mechanisms of an IgG1 but also IgA1, consequently activating neutrophils, in order to combine multiple effector mechanisms. Moreover, to prevent toxicities, these Fc-fusion peptides were cloned in oncolytic adenoviruses whose replication is restricted to the tumor. Our oncolytic adenoviruses were able to selectively infect tumor cells, secrete the cross-hybrid Fc-fusion peptides able to bind to PD-L1 and activate multiple immune components enhancing tumor cytotoxicity compared to FDA-approved immune checkpoint inhibitors. We validated this in various human and murine cancer cell lines and also renal cell carcinoma patient derived organoids from four patients. In conclusion, our cross-hybrid Fc-fusion peptides demonstrate that activating multiple immune effector populations increases tumor cytotoxicity potentially leading to improved clinical outcomes.

Citation Format: Firas Hamdan, Erkko Ylösmäki, Jacopo Chiaro, Yvonne Giannoula, Maeve Long, Manlio Fusciello, Sara Feola, Beatriz Martins, Michaela Feodoroff, Gabriella Antignani, Otto Kari, Moon Hee Lee, Petrus Järvinen, Harry Nisen, Anna Kreutzman, Satu Mustjoki, Thomas G McWilliams, Mikaela Grönholm, Vincenzo Cerullo. Characterization in patient derived tumor organoids of novel oncolytic adenoviruses expressing enhanced cross-hybrid IgGA Fc PD-L1 inhibitors [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 1867.

Complement activation in tear fluid during occupational mold challenge

INTRODUCTION

Indoor air quality is important in occupational healthcare when evaluating the health risks of a work environment. Components of the classical and alternative complement pathways are present in ocular tissues and fluids. The authors determined the levels of complement components C1INH, C3, and C4 in sera and C3a in tear fluids of normal persons and of those who were exposed to molds.

METHODS

Nine patients environmentally exposed to molds and 6 controls were selected from the Indoor Air Clinic of the Skin and Allergy Hospital. Tear fluid samples were collected from patients during the exposure to molds and after 2 weeks without mold exposure. At the same time, conjunctival cytology samples were obtained from each patient. Tear fluid was taken from 6 control subjects. All had negative skin prick tests to common environmental allergens.

RESULTS

In 4 patients subjective eye symptoms and tear fluid C3a levels decreased during 2 weeks of sick leave as did conjunctival eosinophils but other inflammatory cells were unchanged.

CONCLUSION

Elevated complement C3a levels in tear fluids may be influenced by environmental exposure to molds. According to the authors' clinical experience, eosinophilia is not a consistent finding in patients exposed to molds. However, molds may cause eosinophilic inflammation in the eye.

Tolerance to different kinds of contact lenses in young atopic and non-atopic wearers

PURPOSE

To study tolerance to three types of soft and onetype of rigid gas permeable (RGP) contact lens in young atopic and non-atopic subjects starting to wear contact lenses.

METHODS

A prospective study was conducted in 73 young subjects (mean age: 18.7 years, range: 11-37 years). Each subject was allotted at random to one of four groups. Each group of subjects used a different type of contact lens for a year. Tolerance was determined by means of self-assessment by the subjects, ophthalmologic methods, and cytology. The study was conducted on a blind basis. The investigators assessing tolerance did not know what kind of lens a patient had been wearing.

RESULTS

Fifty-six percent of subjects who had used soft contact lenses, but only 14% of RGP lens users described their lenses as very comfortable to wear. Sixty-three percent of non-atopic subjects but only 47% of atopic subjects described their lenses as very comfortable to wear. No differences were found between the three types of soft contact lens. Four cases of giant papillary conjunctivitis (GPC) and two cases of macropapillary reaction were recorded. No connections with atopy, type of lens, or lens care solution were found.

CONCLUSIONS

Higher percentages of users of soft contact lenses than users of RGP contact lenses described their lenses as very comfortable to wear. Wearing of all types of lenses was associated with follicular or papillary reactions in some subjects. Young people can wear contact lenses safely only if monitoring takes place at least twice a year.

Topical lomefloxacin twice daily compared with fucidic acid in acute bacterial conjunctivitis

Forty-five patients with presumed acute bacterial conjunctivitis were treated in an investigator-masked randomized multicenter study with either lomefloxacin 0.3% or fucidic acid 1% eye drops twice daily. Clinical signs and symptoms were rated by slit-lamp examination and conjunctival swab cultures were performed to evaluate clinical and microbiological efficacy. A total of 57 ocular isolates were tested for susceptibility to nine antibiotics. A significant decrease in clinical symptomatology was achieved by both treatments with a gradual improvement over the treatment period of 7-9 days. Bacteriological recovery was frequently achieved already at the first control visit (day 3-5), but the recovery rate was statistically significant (p = 0.014) only in the lomefloxacin group. The relatively high in vitro resistance rate (46%) to fucidic acid was not reflected by lower clinical efficacy. Two unrelated adverse events (one in each treatment group) and minimal local intolerance problems were observed in both treatment groups. A significantly higher incidence of burning sensation was observed with fucidic acid than with lomefloxacin (p < 0.01). All four treatment failures in the study occurred in the fucidic acid group. Lomefloxacin 0.3% ophthalmic solution demonstrated a high efficacy and good tolerance in the management of acute bacterial conjunctivitis.

Occupational conjunctivitis associated with type IV allergy to methacrylates

On rare occasions, exposure to methacrylates (MAs) may induce mucosal symptoms. Three patients, two dental laboratory workers and one hearing aid laboratory worker, are presented. All three had allergic contact dermatitis from MAs which disappeared after avoidance of contact with uncured MA compounds. Two of the patients, the dental laboratory assistant and the hearing aid worker, had also developed symptoms of conjunctivitis. Both were exposed to chemically curable and light-curable MAs. The association between their conjunctivitis and type IV allergy to MAs was supported by the following observations: 1) sensitization to several MAs including methylMA, 2-hydroxyethylMA, ethyleneglycol diMA, triethyleneglycoldiMA, tetrahydrofurfuryldiMA, and 1,4-butanedioldiMA, as well as to pentaerythritol triacrylate; 2) simultaneous appearance of their eye symptoms and allergic contact dermatitis; 3) high exposure to MAs because of disturbances of ventilation; 4) disappearance of the eye symptoms during holidays; and 5) opthalmologist's findings of follicular conjunctivitis with some papillae, eosinophilia, and lymphocytosis in conjunctival scrapings corresponding to allergic contact conjunctivitis. In addition, the activation of eosinophils in the conjunctival scrapings was demonstrated with the monoclonal antibody technique, and an elevated level of eosinophilic cationic protein was found in the tear fluid. Our cases suggest that conjunctivitis may be caused by type IV allergy to MAs, although type I allergy (even though prick tests were negative), other hypersensitivity mechanisms, or irritation cannot be excluded. 4H-Gloves seem to give adequate hand protection even to allergic patients. More attention should be paid to ventilation systems if MA exposure occurs. In some cases, patients with eye symptoms need to be patch tested.

Is atopy a risk factor for the use of contact lenses?

We studied the tolerance of soft contact lenses (CL) in 24 atopic (16 with hay fever) and 52 non-atopic subjects with a mean age of 20 years. They were examined when they first came to an ophthalmologist to have CL and re-examined after an average of 1.7 years. All subjects were allowed to use CL throughout the year, including the pollen season. Of the 76 subjects, 31 (41%) reported some kind of eye symptoms during the use of CL. Six subjects (8%) had stopped using CL because of symptoms. Altogether, in 29/76 subjects (38%) some objective sign was detected in the examination, confirming the subjective symptoms (conjunctivitis 16, keratoconjunctivitis 8, increased limbal blood vessels 4, and eczema palpebrae 1). Fourteen of the 24 atopics (58%) had experienced symptoms compared with 17 of the 52 non-atopics (33%) (p = 0.034). Eleven atopics had seasonal eye symptoms, and eight of them (73%) had problems with CL use. Eosinophils and neutrophils found in the conjunctival scrapings at the first examination appeared to predict poor CL tolerance when the occurrence of symptoms in different groups was first compared by bivariate analysis. The risk factors that could predict poor CL tolerance were also evaluated, with logistic regression analysis controlling potential confounders. History of an atopic condition increased 5-fold the risk of experiencing various external eye symptoms during the use of CL. We conclude that seasonal atopic allergy is a especially risk factor for wearing soft contact lenses, and their use should be restricted during the season.

Conjunctival eosinophilia in atopic and non-atopic external eye symptoms

We studied the occurrence in an ophthalmological office practice of conjunctival eosinophilia in 333 normal subjects (mean age 26 years) and in 152 atopic and 484 non-atopic patients (mean age 40 years) with various external eye symptoms. Eosinophils were present in 131/636 patients (21%) and in 22/333 asymptomatic normal subjects (7%). In those patients with conjunctival eosinophilia, a history of some kind of atopic condition was obtained only in 53/131 (40%). When the patients were characterized according to the presence of both eosinophilia and atopy, eosinophilia without signs of atopy was observed in 7-15% in different diagnostic groups. Patients with conjunctivitis or blepharoconjunctivitis had a fourfold risk for eosinophilia compared to normal subjects (odds ratios 4.52 and 4.09, confidence intervals 2.02, 10.12 and 2.40, 6.99), when atopy, sex, age, time of the examination and presence of bacteria were included as potential confounders in the regression model. We conclude that a considerable portion of patients with external eye symptoms, and especially with various forms of conjunctivitis, show eosinophilic inflammation without any evidence of atopic background. They can be labelled as having 'intrinsic' eosinophilic conjunctivitis analogously to the classification used in patients with intrinsic rhinitis and asthma. The etiology of this common nonatopic syndrome remains to be established.

Atopic conjunctivitis. A cytologic examination

Tarsal conjunctival scrapings of the lower and upper eyelids of 21 atopic, pollen allergic patients with conjunctivitis were examined three times; during a symptom-free period, during a challenge test and during the pollen season. Eosinophils were also counted from the conjunctival fluid of 17 patients, but only of 12 patients during the challenge. The controls were 10 atopic patients without conjunctivitis (K0), 31 normal persons (K1), who were examined routinely in the course of a spectacle prescription and 45 patients with acute conjunctivitis (K2) of other than allergic origin. A statistically significant difference in the occurrence of eosinophils in the scrapings was found between the pollen allergic patients and the normal control patients but not between patients with atopic or non-atopic conjunctivitis. During the challenge test, the occurrence of eosinophils in the scrapings increased for at least an hour after the challenge had become positive. In the pollen allergic patients eosinophils were equally abundant during the symptom-free and pollen seasons. It is concluded that the occurrence of eosinophils in the conjunctival scraping is not a reliable clinical indicator of allergy.

Allergic conjunctivitis, total and specific IgE in the tear fluid

Twenty-three patients with allergic conjunctivitis caused by birch, timothy or mugwort pollen were examined for the presence of total and specific IgE in the tear fluid. In thirteen of the 23 patients IgE could be shown in the tears. Specific IgE antibodies against the causative pollens were present in the tear fluid of 8 of the patients. The relation between serum and tear IgE on one hand and serum and tear albumin on the other hand suggests local production of the specific IgE antibody.