Leonardo Giovannoni

Expression of the oncofetal ED-B containing fibronectin isoform in hematologic tumors enables ED-B targeted 131I-L19SIP radioimmunotherapy in Hodgkin lymphoma patients

Current treatment of hematologic malignancies involves rather unspecific chemotherapy, frequently resulting in severe adverse events. Thus, modern clinical research focuses on compounds able to discriminate malignant from normal tissues. Being expressed in newly formed blood vessels of solid cancers but not in normal mature tissues, the extradomain B of fibronectin (ED-B FN) is a promising target for selective cancer therapies. Using immunohistology with a new epitope retrieval technique for paraffin-embedded tissues, ED-B FN expression was found in biopsies from more than 200 Hodgkin and non-Hodgkin lymphoma patients of nearly all entities, and in patients with myeloproliferative diseases. ED-B FN expression was nearly absent in normal lymph nodes (n = 10) and bone marrow biopsies (n = 9). The extent of vascular ED-B FN expression in lymphoma tissues was positively correlated with grade of malignancy. ED-B FN expression was enhanced in lymph nodes with severe lymphadenopathy and in some hyperplastic tonsils. The in vivo accessibility of ED-B FN was confirmed in 3 lymphoma patients, in whom the lymphoma lesions were visualized on scintigraphy with (131)I-labeled L19 small immunoprotein ((131)I-L19SIP). In 2 relapsed Hodgkin lymphoma patients(131)I-L19SIP radioimmunotherapy induced a sustained partial response, qualifying ED-B FN as a promising target for antibody-based lymphoma therapies.

The tumour-targeting human L19-IL2 immunocytokine: Preclinical safety studies, phase I clinical trial in patients with solid tumours and expansion into patients with advanced renal cell carcinoma

BACKGROUND L19-IL2, a tumour-targeting immunocytokine composed of the recombinant human antibody fragment L19 (specific to the alternatively-spliced EDB domain of fibronectin, a well characterised marker of tumour neo-vasculature) and of human IL2, has demonstrated strong therapeutic activity in animal cancer models. This phase I/II trial was performed to evaluate safety, tolerability, recommended phase II dose (RD) and early signs of activity of L19-IL2. PATIENTS AND METHODS Five cohorts of patients with progressive solid tumours (n=21) received an intravenous infusion of L19-IL2 (from 5 to 30 Mio IU IL2 equivalent dose) on days 1, 3 and 5 every 3 weeks. This treatment cycle was repeated up to six times. In the following expansion phase, patients with metastatic renal cell carcinoma (RCC) (n=12) were treated at the RD of L19-IL2. Clinical data and laboratory findings were analysed for safety, tolerability and activity. RESULTS Preclinical studies in rats and monkeys did not raise any safety concerns. The RD was defined to be 22.5 Mio IU IL2 equivalent. Pharmacokinetics of L19-IL2 was dose proportional over the tested range, with a terminal half-life of 2-3h. Toxicities were manageable and reversible with no treatment-related deaths. We observed stable disease in 17/33 patients (51%) and 15/18 with mRCC (83%) after two cycles. Median progression-free survival of RCC patients in the expansion phase of the study was 8 months (1.5-30.5). CONCLUSIONS L19-IL2 can be safely and repeatedly administered at the RD of 22.5 Mio IU IL2 equivalent in advanced solid tumours. Preliminary evaluation suggests clinical activity of L19-IL2 in patients with mRCC.

A Dose-Escalation and Signal-Generating Study of the Immunocytokine L19-IL2 in Combination with Dacarbazine for the Therapy of Patients with Metastatic Melanoma

Purpose: L19-IL2 is an immunocytokine composed of an antibody fragment specific to the EDB domain of fibronectin, a tumor angiogenesis marker, and of human interleukin-2 (IL2). L19-IL2 delivers IL2 to the tumor site exploiting the selective expression of EDB on newly formed blood vessels. Previously, the recommended dose of L19-IL2 monotherapy was defined as 22.5 million international units (Mio IU) IL2 equivalents. In this study, safety and clinical activity of L19-IL2 in combination with dacarbazine were assessed in patients with metastatic melanoma. Experimental Design: The first 10 studied patients received escalating doses of L19-IL2 on days 1, 3, and 5 in combination with 1 g/m2 of dacarbazine on day 1 of a 3-weekly therapy cycle. Subsequently, 22 patients received L19-IL2 at recommended dose plus dacarbazine. Up to six treatment cycles were given, followed by a maintenance regimen with biweekly L19-IL2. Results: The recommended dose of L19-IL2 in combination with dacarbazine was defined as 22.5 Mio IU. Toxicity was manageable and reversible, with no treatment-related deaths. Twenty-nine patients were evaluable for efficacy according to Response Evaluation Criteria in Solid Tumors (RECIST). In a centralized radiology analysis, eight of 29 (28%) patients achieved a RECIST-confirmed objective response, including a complete response still ongoing 21 months after treatment beginning. The 12-month survival rate and median overall survival of the recommended dose–treated patients (n = 26) were 61.5% and 14.1 months, respectively. Conclusions: The repeated administration of L19-IL2 in combination with dacarbazine is safe and shows encouraging signs of clinical activity in patients with metastatic melanoma. This combination therapy is currently evaluated in a randomized phase II trial with patients with metastatic melanoma. Clin Cancer Res; 17(24); 7732–42. ©2011 AACR.

Antibody-Mediated Delivery of Interleukin-2 to the Stroma of Breast Cancer Strongly Enhances the Potency of Chemotherapy

Purpose: There is an interest in the discovery of biopharmaceuticals, which are well tolerated and which potentiate the action of anthracyclines and taxanes in breast cancer therapy. Experimental Design: We have produced a recombinant fusion protein, composed of the human antibody fragment scFv(F16) fused to human interleukin-2 (F16-IL2), and tested its therapeutic performance in the MDA-MB-231 xenograft model of human breast cancer. The F16 antibody is specific to the alternatively spliced A1 domain of tenascin-C, which is virtually undetectable in normal tissues but is strongly expressed in the neovasculature and stroma of breast cancer. Results: When used as monotherapy, F16-IL2 displayed a strikingly superior therapeutic benefit compared with unconjugated recombinant IL-2. The administration of doxorubicin either before (8 days, 24 h, or 2 h) or simultaneously with the injection of F16-IL2 did not decrease the accumulation of immunocytokine in the tumor as measured by quantitative biodistribution analysis. Therapy experiments, featuring five once per week coadministrations of 20 μg F16-IL2 and doxorubicin, showed a statistically significant reduction of tumor growth rate and prolongation of survival at a 4 mg/kg doxorubicin dose but not at a 1 mg/kg dose. By contrast, combination of F16-IL2 with paclitaxel (5 and 1 mg/kg) exhibited a significant therapeutic benefit compared with paclitaxel alone at both dose levels. F16-IL2, alone or in combination with doxorubicin, was well tolerated in cynomolgus monkeys at doses equivalent to the ones now used in clinical studies. Conclusions: F16-IL2 may represent a new useful biopharmaceutical for the treatment of breast cancer.

Antibody-Based Delivery of Interleukin-2 to Neovasculature Has Potent Activity Against Acute Myeloid Leukemia

Neovascular structures in acute myeloid leukemia can be targeted using a cognate antibody fused to human interleukin-2. The Blood Mobile For solid tumors, new blood vessel formation—angiogenesis—is thought to be critical to bring oxygen and nutrients to all parts of the tumors, and targeting these new vessels has long been a focus of cancer therapy development. However, angiogenesis-targeting therapy has been relatively neglected in the context of blood-borne tumors like leukemias. Now, Gutbrodt et al. find that targeting neovascular structures found in the bone marrow of patients with acute myeloid leukemia (AML) has activity against blood-borne cancers as well. The authors observed that AML patients have increased blood vessel density in the bone marrow, and that these vessels could be stained by clinical-stage human antibodies against tumor angiogenesis markers. They then took this observation into mouse models and found that if they fused interleukin-2 to the targeting antibody, they could inhibit AML progression. The effect was further enhanced by combination with the chemotherapeutic cytarabine. Indeed, this effect was long-lasting in immunocompetent mice and was mediated by both natural killer and CD8+ T cells. Early results from clinical trials support these results in human patients, although further trials are needed to confirm efficacy. Acute myeloid leukemia (AML) is a rapidly progressing disease that is accompanied by a strong increase in microvessel density in the bone marrow. This observation prompted us to stain biopsies of AML and acute lymphoid leukemia (ALL) patients with the clinical-stage human monoclonal antibodies F8, L19, and F16 directed against markers of tumor angiogenesis. The analysis revealed that the F8 and F16 antibodies strongly stained 70% of AML and 75% of ALL bone marrow specimens, whereas chloroma biopsies were stained with all three antibodies. Therapy experiments performed in immunocompromised mice bearing human NB4 leukemia with the immunocytokine F8-IL2 [consisting of the F8 antibody fused to human interleukin-2 (IL-2)] mediated a strong inhibition of AML progression. This effect was potentiated by the addition of cytarabine, promoting complete responses in 40% of treated animals. Experiments performed in immunocompetent mice bearing C1498 murine leukemia revealed long-lasting complete tumor eradication in all treated mice. The therapeutic effect of F8-IL2 was mediated by both natural killer cells and CD8+ T cells, whereas CD4+ T cells appeared to be dispensable, as determined in immunodepletion experiments. The treatment of an AML patient with disseminated extramedullary AML manifestations with F16-IL2 (consisting of the F16 antibody fused to human IL-2, currently being tested in phase 2 clinical trials in patients with solid tumors) and low-dose cytarabine showed significant reduction of AML lesions and underlines the translational potential of vascular tumor–targeting antibody-cytokine fusions for the treatment of patients with leukemia.

Isolated Limb Perfusion With the Tumor-Targeting Human Monoclonal Antibody-Cytokine Fusion Protein L19-TNF Plus Melphalan and Mild Hyperthermia in Patients with Locally Advanced Extremity Melanoma

L19‐TNF is a tumor‐targeting immunocytokine composed of the human L19 antibody binding to extra domain B (ED‐B) of fibronectin of newly formed blood vessels, and of human TNF. This exploratory trial evaluates safety and clinical activity of L19‐TNF plus melphalan‐containing isolated limb perfusion (ILP) in extremity melanoma patients.

Radioimmunotherapy with Radretumab in Patients with Relapsed Hematologic Malignancies

We present here a systematic analysis of lymphoma and MM patients recruited into 2 clinical trials or treated with radretumab according to compassionate use, describing the biodistribution, dosimetry, safety, and clinical activity of radretumab. Methods: Uptake in lymphoma lesions, safety, and clinical activity of radretumab radioimmunotherapy (R-RIT) were evaluated in 18 relapsed lymphoma or multiple myeloma patients. Results: In 14 of 18 patients, selective tumor uptake was found; 11 of 15 lymphoma patients, including 9 of 11 with Hodgkin lymphoma (HL), were eligible for R-RIT (a priori criteria–based target-to-bone marrow ratio > 10:1 for EudraCT no. 2005-000545 or > 4:1 for EudraCT no. 2007-007241-12 at dosimetric imaging). Two HL and 1 diffuse large B cell lymphoma patient achieved complete response; 1 HL patient had partial response. Both multiple myeloma patients receiving R-RIT experienced stabilization of disease. Therefore, the overall objective response rate was 40%. Uncomplicated grade 3–4 thrombocytopenia or leukocytopenia was observed in 5 R-RIT patients, lasting 4–129 d. Conclusion: R-RIT showed a favorable benefit and risk profile in advanced relapsed lymphoma patients and induced complete response in 2 heavily pretreated, relapsed HL patients and in 1 diffuse large B cell lymphoma patient. These results warrant further exploration of R-RIT in larger phase II clinical trials.

Intralesional Treatment of Stage III Metastatic Melanoma Patients with L19-IL2 Results in Sustained Clinical and Systemic Immunologic Responses

Weide and colleagues show that intralesional therapy using the immunocytokine L19–IL2 elicited a high rate of clinical and systemic immune responses in patients with stage III melanoma and report their observation of favorable distant metastasis-free and overall survival in these patients after treatment. L19–IL2 is a recombinant protein comprising the cytokine IL2 fused to the single-chain monoclonal antibody L19. In previous studies, intralesional injection with IL2 has shown efficacy for the locoregional treatment of cutaneous/subcutaneous metastases in patients with advanced melanoma. The objectives of this study were to investigate whether (i) intralesional delivery of a targeted form of IL2 would yield similar results, with reduction of injection frequency and treatment duration; and (ii) systemic immune responses were induced by the local treatment. Patients with stage IIIB/IIIC melanoma and cutaneous/subcutaneous injectable metastases received weekly intratumoral injections of L19–IL2 at a maximum dose of 10 MIU/week for 4 consecutive weeks. Tumor response was evaluated 12 weeks after the first treatment. Twenty-four of 25 patients were evaluable for therapy-induced responses. A complete response (CR) by modified immune-related response criteria (irRC) of all treated metastases was achieved in 6 patients (25%), with long-lasting responses in most cases (5 patients for ≥24 months). Objective responses were documented in 53.9% of all index lesions [44.4% CR and 9.5% partial responses (by irRC)], and 36.5% of these remained stable, while 9.5% progressed. Toxicity was comparable with that of free IL2, and no serious adverse events were recorded. A significant temporary increase of peripheral regulatory T cells and natural killer cells, sustained increase of absolute CD4+ lymphocytes, and decrease of myeloid-derived suppressor cells were observed upon treatment. Finally, we recorded encouraging data about the progression time to distant metastases and overall survival. Cancer Immunol Res; 2(7); 668–78. ©2014 AACR.

The antibody-based targeted delivery of TNF in combination with doxorubicin eradicates sarcomas in mice and confers protective immunity

Background:Soft-tissue sarcomas are a group of malignancies of mesenchymal origin, which typically have a dismal prognosis if they reach the metastatic stage. The observation of rare spontaneous remissions in patients suffering from concomitant bacterial infections had triggered the clinical investigation of the use of heat-killed bacteria as therapeutic agents (Coley’s toxin), which induced complete responses in patients in the pre-chemotherapy era and is now known to mediate substantial elevations in serum TNF levels.Methods:We designed and developed a novel immunocytokine based on murine TNF sequentially fused to the antibody fragment F8 (specific to extra-domain A of fibronectin). The antitumor activity was studied in two syngeneic murine sarcoma models.Results:The L19 antibody (specific to extra-domain B of fibronectin) has shown by SPECT imaging procedures to selectively localise on sarcoma in a patient with a peripheral nerve sheath tumour, and immunohistochemical analysis of human soft-tissue sarcoma samples showed comparable antigen expression of EDA and EDB. The antibody-based pharmacodelivery of TNF by the fusion protein ‘F8–TNF’ to oncofetal fibronectin in sarcoma-bearing mice leads to complete and long-lasting tumour eradications when administered in combination with doxorubicin, the first-line drug for the treatment of sarcomas in humans. Doxorubicin alone did not display any therapeutic effect in both tested models of this study. The cured mice had acquired protective immunity against the tumour, as they rejected subsequent challenges with sarcoma cells.Conclusion:The findings of this study provide a rationale for the clinical study of the fully human immunocytokine L19-TNF in combination with doxorubicin in patients with soft-tissue sarcoma.

Phase 0 Microdosing PET Study Using the Human Mini Antibody F16SIP in Head and Neck Cancer Patients

The aim of this microdosing phase 0 clinical study was to obtain initial information about pharmacokinetics, biodistribution, and specific tumor targeting of the antitenascin-C mini antibody F16SIP. Methods: Two milligrams of F16SIP, labeled with 74 MBq of 124I, were intravenously administered to patients with head and neck cancer (n = 4) scheduled for surgery 5–7 d later. Immuno-PET scans were acquired at 30 min and 24 h after injection. For pharmacokinetic analysis, blood samples were taken at different time points after infusion. Tissue uptake was extracted from whole-body PET scans. In addition, ex vivo radioactivity measurements of blood and of biopsies from the surgical specimens were performed. Results: 124I-F16SIP was well tolerated. Uptake was visible mainly in the liver, spleen, kidneys, and bone marrow and diminished over time. Tumor uptake increased over time, with all 4 tumors visible on 24-h PET images. The tumor-to-blood ratio was 7.7 ± 1.7 at the time of surgery. Pharmacokinetic analysis revealed good bioavailability of 124I-F16SIP. Conclusion: Performing a microdosing immuno-PET study appeared feasible and demonstrated adequate bioavailability and selective tumor targeting of 124I-F16SIP.The results of this study justify further clinical exploration of 124I-F16SIP-based therapies.