Boosting cytotoxicity of adoptive allogeneic NK cell therapy with an oncolytic adenovirus encoding a human vIL-2 cytokine for the treatment of human ovarian cancer

Despite good results in the treatment of hematological malignancies, Natural killer (NK) cells have shown limited effectiveness in solid tumors, such as ovarian cancer (OvCa). Here, we assessed the potential of an oncolytic adenovirus expressing a variant interleukin-2 (vIL-2) cytokine, Ad5/3-E2F-d24-vIL2 (vIL-2 virus), also known as TILT-452, to enhance NK cell therapy efficacy in human OvCa ex vivo. Human OvCa surgical specimens were processed into single-cell suspensions and NK cells were expanded from healthy blood donors. OvCa sample digests were co-cultured ex vivo with NK cells and vIL-2 virus and cancer cell killing potential assessed in real time through cell impedance measurement. Proposed therapeutic combination was evaluated in vivo with an OvCa patient-derived xenograft (PDX) in mice. Addition of vIL-2 virus significantly enhanced NK cell therapy killing potential in treated OvCa co-cultures. Similarly, vIL-2 virus in combination with NK cell therapy promoted the best in vivo OvCa tumor control. Mechanistically, vIL-2 virus induced higher percentages of granzyme B in NK cells, and CD8+ T cells, while T regulatory cell proportions remained comparable to NK cell monotherapy in vivo. Ad5/3-E2F-d24-vIL2 virus treatment represents a promising strategy to boost adoptive NK cell therapeutic effect in human OvCa.

Improving the cytotoxic response of tumor-infiltrating lymphocytes towards advanced stage ovarian cancer with an oncolytic adenovirus expressing a human vIL-2 cytokine

While the presence of tumor-infiltrating lymphocytes (TILs) associates with improved survival prognosis in ovarian cancer (OvCa) patients, TIL therapy benefit is limited. Here, we evaluated an oncolytic adenovirus coding for a human variant IL-2 (vIL-2) cytokine, Ad5/3-E2F-d24-vIL2 (vIL-2 virus), also known as TILT-452, as an immunotherapeutic strategy to enhance TIL responsiveness towards advanced stage OvCa tumors. Fragments of resected human OvCa tumors were processed into single-cell suspensions, and autologous TILs were expanded from said samples. OvCa tumor specimens were co-cultured with TILs plus vIL-2 virus, and cell killing was assessed in real time through cell impedance measurement. Combination therapy was further evaluated in vivo through a patient-derived xenograft (PDX) ovarian cancer murine model. The combination of vIL-2 virus plus TILs had best cancer cell killing ex vivo compared to TILs monotherapy. These results were supported by an in vivo experiment, where the best OvCa tumor control was obtained when vIL-2 virus was added to TIL therapy. Furthermore, the proposed therapy induced a highly cytotoxic phenotype demonstrated by increased granzyme B intensity in NK cells, CD4+ T, and CD8+ T cells in treated tumors. Our results demonstrate that Ad5/3-E2F-d24-vIL2 therapy consistently improved TILs therapy cytotoxicity in treated human OvCa tumors.

Catheter-directed thrombolysis with microplasmin for acute peripheral arterial occlusion (PAO): an exploratory study

AIM

We performed an open-label, dose-ascending, single-centre, Phase IIa study to explore the safety and efficacy of catheter-directed thrombolysis (CDT) with microplasmin for infrainguinal arterial or bypass occlusions.

METHODS

Patients who presented with acute occlusions were subsequently treated with an intrathrombus infusion of five ascending doses of microplasmin: 0.3 mg/kg/h for 4 hours; 0.45 mg/kg/h for 4 hours; 0.6 mg/kg/h for 4 hours; 0.9 mg/kg/h for 4 hours or 0.6 mg/kg/h for 6 hours. Repeat angiograms were obtained to assess the degree of clot lysis. The primary outcome was complete thrombolysis defined as >95% thrombus volume reduction at the end of the microplasmin infusion. Safety evaluation included bleedings, adverse events and coagulation biomarkers.

RESULTS

Complete thrombolysis was obtained in 3 of the 19 treated patients at the end of microplasmin infusion. Thrombus volume reduction between 50% and 95% was achieved with all dosing regimens. Clinically significant distal embolization occurred in 8 patients. One major and two non-major bleedings occurred. Microplasmin depleted α2-anti-plasmin and decreased fibrinogen.

CONCLUSION

Intrathrombus infusion of microplasmin for 4 or 6 hours resulted in significant clot lysis. Distal embolization appeared the most important limitation.

Collaborative Angiographic Patency Trial Of Recombinant Staphylokinase (CAPTORS II)

AIMS

A fibrinolytic agent more effective than streptokinase available for bolus injection with reasonable cost-effectiveness is a desirable goal. Pilot studies with bolus pegulated staphylokinase (PEG-Sak) have revealed excellent Thrombolysis In Myocardial Infarction (TIMI) 3 60-minute flow.

METHODS AND RESULTS

We evaluated patients with acute ST-elevation myocardial infarction within 6 hours of chest pain onset to determine a dose of PEG-Sak that had at least equal efficacy to recombinant tissue plasminogen activator (rt-PA) while maintaining an acceptable safety profile. After the initial study of 38 patients, of whom 27 received PEG-Sak, enrollment was temporarily halted because 3 patients receiving PEG-Sak had intracranial hemorrhage: 1 at a dose of 0.15 mg/kg and 2 at a dose of 0.05 mg/kg. Overall, 378 patients were studied across a PEG-Sak dose range from 0.01 mg/kg to 0.015 mg/kg, and 122 patients received accelerated rt-PA. At the lowest dose of PEG-Sak studied, 0.01 mg/kg, there was suggestive evidence of attenuation of efficacy; the point estimate for TIMI 3 flow was 24% (95% CI 9%-38%). At doses of 0.01875 to 0.0375 mg/kg (n = 314), TIMI 3 flow rates were 33% (95% CI 27%-38%), whereas the TIMI 3 flow was 41% (95% CI 20%-61%) at the highest PEG-Sak dose studied, 0.05 mg/kg (n = 23), which was similar to that found with rt-PA, 41% (95% CI 32%-50%).

CONCLUSION

The efficacy of PEG-Sak, coupled with its ease of administration, provide further impetus for further study in acute myocardial infarction.

Humoral response after administration of E1-deleted adenoviruses: immune privilege of the subretinal space

An important limitation of E1-deleted recombinant adenoviruses in gene therapy is the immune response that they engender and that rapidly destroys transduced cells. Transduced cells of the outer retina appear to be an exception. To determine whether differences in immune sequestration of the outer retina contribute to the increased stability of transgene expression in this tissue, we examined the systemic humoral response to an E1-deleted adenovirus injected into the subretinal space. Subretinal injection of Ad.CMVlacZ in mature immunocompetent mice resulted in minimal circulating antibody production. In contrast, subcutaneous administration of equivalent doses of Ad.CMVlacZ resulted in high-titer antibody production against adenoviral proteins. Circulating antibodies in systemically immunized animals had minimal effect on retinal transgene expression patterns measured 2 weeks after subretinal injection of Ad.CMVlacZ. Histologic examination showed minimal retinal toxicity attributable to subretinal adenovirus in naive or immunized mice, although 3/18 (14%) of eyes from the latter set contained a localized granulomatous infiltrate at the ocular injection site. The data demonstrate that the subretinal space is an immune-privileged site regarding humoral immunity. Further, short-term transduction efficiency is not affected by the presence of anti-adenoviral antibodies. The retina may be a favorable environment for replication-defective virus-mediated genetic therapy.