Abstract CT101: Phase I safety and bioimaging trial of ifabotuzumab in patients with glioblastoma

Overview Glioblastoma multiforme (GBM) is the most frequent and lethal primary brain neoplasm, with only 10% of patients surviving 5 years.1 EphA3 is a tumor restricted antigen expressed in various solid tumors and the tumor vasculature of 100% of GBM.2,3 Ifabotuzumab is a non-fucosylated IgG1κ humaneered antibody targeting the EphA3 receptor.4 A Phase I study of ifabotuzumab in haematological malignancies showed it was well tolerated and clinically active.5 Here we report on a Phase I dose escalation and biodistribution study of ifabotuzumab in recurrent GBM. Study Design The primary objective is to determine the safety and recommended Phase II dose of ifabotuzumab in GBM patients (pts). Secondary objectives are to determine the biodistribution and pharmacokinetics (PK) of 89Zr- ifabotuzumab, the frequency of EphA3 positive GBM and response rates. On day 1, eligible pts with measurable tumors received a trace (5mg) dose of zirconium labelled ifabotuzumab (89Zr-ifab) followed by sequential PET imaging over 1 week to determine its biodistribution, frequency of in situ EphA3 expression and quantitative tumor uptake. Safety assessments and PK sampling were also undertaken. On day 8, pts commenced weekly ifabotuzumab infusions over 2 hours in one of two cohorts (3.5mg/kg, 5.25 mg/kg). On day 36, pts received both 89Zr-ifab and ifabotuzumab, allowing assessment of receptor occupancy. Response rate (RANO) and survival data were collected. Pts then continued on ifabotuzumab until progression. Results In total, 12 pts have been enrolled, including 6 in the 3.5mg/kg and 6 in the 5.25 mg/kg dose cohorts. Mean age was 51.6 years (±14.24) and 7/12 pts were male. Treatment emergent adverse events included infusion reactions in 4 pts, seizures in 3 pts, cerebral oedema in 1, rash in 1, headaches in 8, eye disorder in 1. Most were considered related to study drug except seizure in 2 pts, headaches and eye disorder. Seizures and infusion reactions were readily managed with increased premedications after the first occurrence. The best response was stable disease for 23 weeks. 89Zr-ifab-PET scans showed rapid, tumor-specific targeting at all known tumor sites and in all pts, but with no normal tissue uptake. MRI scans showed predominant T2/FLAIR changes, occasionally marked, which were consistent with treatment effect of ifabotuzumab on tumor vasculature. The mean ± SD (n=12) PK parameters for first infusion 89Zr-ifab were T½α= 9.03 ± 4.45 hr, T½β = 92.50 ± 65.65 hr, V1 = 3.75 ± 0.67 L, CL= 132.11 ± 70.16 mL/hr. Conclusions: Ifabotuzumab demonstrates highly sensitive, specific and reproducible targeting of the tumor and tumor microenvironment in all patients in this study. The imaging changes suggest direct modulation of the tumor vasculature. Additional studies are planned to evaluate ifabotuzumab as part of an antibody-drug conjugate in various solid tumor types. References: 1. Stupp R, et al, Lancet Oncology 10:459-66, 2009 2. Day BW, et al. Cancer Cell 23:238-48, 2013 3. Vail ME, et al. Cancer Research 74:4470-81, 2014 4. Tomasevic N, et al. Growth Factors 32:223-35, 2014 5. Swords RT, et al. Leukemia Research 50:123-131, 2016

Citation Format: Hui K. Gan, Lawrence Cher, Po Inglis, Zarnie Lwin, Eddie Lau, Christian Wichmann, Alex McDonald, Ashray Gunjur, Uwe Ackermann, Kirsten Remen, Kate Fluck, Gel Bolarnos, Nancy Guo, Sze Ting Lee, Sylvia Gong, Jodie B. Palmer, Kunthi Pathmaraj, Graeme J. O'Keefe, Fiona E. Scott, Bryan W. Day, Andrew W. Boyd, Paul Thomas, Omar Ahmed, Dale Chappell, Cameron Durrant, Andrew M. Scott. Phase I safety and bioimaging trial of ifabotuzumab in patients with glioblastoma [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 CT101.

A clinical trial of non-invasive imaging with an anti-HIV antibody labelled with copper-64 in people living with HIV and uninfected controls

BACKGROUND

A research priority in finding a cure for HIV is to establish methods to accurately locate and quantify where and how HIV persists in people living with HIV (PLWH) receiving suppressive antiretroviral therapy (ART). Infusing copper-64 (64Cu) radiolabelled broadly neutralising antibodies targeting HIV envelope (Env) with CT scan and positron emission tomography (PET) identified HIV Env in tissues in SIV infected non-human primates . We aimed to determine if a similar approach was effective in people living with HIV (PLWH).

METHODS

Unmodified 3BNC117 was compared with 3BNC117 bound to the chelator MeCOSar and 64Cu (64Cu-3BNC117) in vitro to assess binding and neutralization. In a clinical trial 64Cu-3BNC117 was infused into HIV uninfected (Group 1), HIV infected and viremic (viral load, VL >1000 c/mL; Group 2) and HIV infected aviremic (VL <20 c/mL; Group 3) participants using two dosing strategies: high protein (3mg/kg unlabeled 3BNC117 combined with <5mg 64Cu-3BNC117) and trace (<5mg 64Cu-3BNC117 only). All participants were screened for 3BNC117 sensitivity from virus obtained from viral outgrowth. Magnetic resonance imaging (MRI)/PET and pharmacokinetic assessments (ELISA for serum 3BNC117 concentrations and gamma counting for 64Cu) were performed 1, 24- and 48-hours post dosing. The trial (clincialtrials.gov NCT03063788) primary endpoint was comparison of PET standard uptake values (SUVs) in regions of interest (e.g lymph node groups and gastrointestinal tract).

FINDINGS

Comparison of unmodified and modified 3BNC117 in vitro demonstrated no difference in HIV binding or neutralisation. 17 individuals were enrolled of which 12 were dosed including Group 1 (n=4, 2 high protein, 2 trace dose), Group 2 (n=6, 2 high protein, 4 trace) and Group 3 (n=2, trace only). HIV+ participants had a mean CD4 of 574 cells/microL and mean age 43 years. There were no drug related adverse effects and no differences in tissue uptake in regions of interest (e.g lymph node gut, pharynx) between the 3 groups. In the high protein dosing group, serum concentrations of 3BNC117 and gamma counts were highly correlated demonstrating that 64Cu-3BNC117 remained intact in vivo.

INTERPRETATION

In PLWH on or off ART, the intervention of infusing 64Cu-3BNC117 and MRI/PET imaging over 48 hours, was unable to detect HIV-1 env expression in vivo. Future studies should investigate alternative radiolabels such as zirconium which have a longer half-life in vivo.

FUNDING

Funded by the Alfred Foundation, The Australian Centre for HIV and Hepatitis Virology Research with additional support from the Division of AIDS, National Institute of Allergy and Infectious Disease, US National Institutes of Health (USAI126611). JHM and SRL are supported by the Australian National Health and Medical Research Council.

Expression of EGFR and conformational forms of EGFR in malignant pleural mesothelioma and its impact on survival

AIM

Conformational forms of the epidermal growth factor receptor (EGFR) are pro-tumorigenic. The prevalence and impact of conformational forms of EGFR in malignant mesothelioma (MM) is unknown. We investigated expression of EGFR and conformational forms of EGFR by immunohistochemistry using EGFR-targeting monoclonal antibodies (mAb). In addition, EGFR gene amplification was investigated by fluorescent in-situ hybridization (FISH). Findings were correlated with survival.

METHODS

Patients treated between 1988 and 2014 were identified from the thoracic surgery database of the Austin Hospital, Melbourne, Australia. Tissue microarrays (TMAs) were constructed, subjected to wild type (wt) EGFR IHC staining and FISH analysis. Conformational and mutation forms of EGFR were detected by IHC using mAb806, and LMH-151 which detects EGFRVIII. `H-scores` were derived and EGFR expression correlated with survival by Kaplan-Meier and log rank analysis.

RESULTS

WtEGFR expression was seen in 93 % (299/321) of cases with overexpression (defined as an H-score ≥200) seen in more than half of cases (64 %). EGFR overexpression in MM was seen more commonly in the epithelioid subtype. EGFR overexpression was not associated with true EGFR amplification, although multiple copies were appreciated in samples with polysomy. EGFR expression did not correlate with survival. A conformational form of EGFR associated with EGFR dysregulation was found in 8.2 % of cases, and patients with these tumors had a trend towards a poorer outcome. No cases of the EGFRVIII mutation were identified.

CONCLUSION

MM consistently demonstrated high expression of EGFR, with a subset of tumors showing conformational EGFR forms consistent with EGFR dysregulation, but withoutEGFR amplification or EGFR VIII mutation. wtEGFR expression did not influence survival. The impact of EGFR conformation on survival warrants further investigation.

First clinical study of a pegylated diabody 124I-labeled PEG-AVP0458 in patients with tumor-associated glycoprotein 72 positive cancers

Through protein engineering and a novel pegylation strategy, a diabody specific to tumor-associated glycoprotein 72 (TAG-72) (PEG-AVP0458) has been created to optimize pharmacokinetics and bioavailability to tumor. We report the preclinical and clinical translation of PEG-AVP0458 to a first-in-human clinical trial of a diabody. Methods: Clinical translation followed characterization of PEG-AVP0458 drug product and preclinical biodistribution and imaging assessments of Iodine-124 trace labeled PEG-AVP0458 (¹²⁴I-PEG-AVP0458). The primary study objective of the first-in-human study was the safety of a single protein dose of 1.0 or 10 mg/m^{2 124}I-PEG-AVP0458 in patients with TAG-72 positive relapsed/ metastatic prostate or ovarian cancer. Secondary study objectives were evaluation of the biodistribution, tumor uptake, pharmacokinetics and immunogenicity. Patients were infused with a single-dose of ¹²⁴I labeled PEG-AVP0458 (3-5 mCi (111-185 MBq) for positron emission tomography (PET) imaging, performed sequentially over a one-week period. Safety, pharmacokinetics, biodistribution, and immunogenicity were assessed up to 28 days after infusion. Results: PEG-AVP0458 was radiolabeled with ¹²⁴I and shown to retain high TAG-72 affinity and excellent targeting of TAG-72 positive xenografts by biodistribution analysis and PET imaging. In the first-in-human trial, no adverse events or toxicity attributable to ¹²⁴I-PEG-AVP0458 were observed. Imaging was evaluable in 5 patients, with rapid and highly specific targeting of tumor and minimal normal organ uptake, leading to high tumor:blood ratios. Serum concentration values of ¹²⁴I-PEG-AVP0458 showed consistent values between patients, and there was no significant difference in T½α and T½β between dose levels with mean (± SD) results of T½α = 5.10 ± 4.58 hours, T½β = 46.19 ± 13.06 hours. Conclusions: These data demonstrates the safety and feasibility of using pegylated diabodies for selective tumor imaging and potential delivery of therapeutic payloads in cancer patients.

Development of monoclonal anti-PDGF-CC antibodies as tools for investigating human tissue expression and for blocking PDGF-CC induced PDGFRα signalling in vivo

PDGF-CC is a member of the platelet-derived growth factor (PDGF) family that stimulates PDGFRα phosphorylation and thereby activates intracellular signalling events essential for development but also in cancer, fibrosis and neuropathologies involving blood-brain barrier (BBB) disruption. In order to elucidate the biological and pathological role(s) of PDGF-CC signalling, we have generated high affinity neutralizing monoclonal antibodies (mAbs) recognizing human PDGF-CC. We determined the complementarity determining regions (CDRs) of the selected clones, and mapped the binding epitope for clone 6B3. Using the monoclonal 6B3, we determined the expression pattern for PDGF-CC in different human primary tumours and control tissues, and explored its ability to neutralize PDGF-CC-induced phosphorylation of PDGFRα. In addition, we showed that PDGF-CC induced disruption of the blood-retinal barrier (BRB) was significantly reduced upon intraperitoneal administration of a chimeric anti-PDGF-CC antibody. In summary, we report on high affinity monoclonal antibodies against PDGF-CC that have therapeutic efficacy in vivo.

Phase I Imaging and Pharmacodynamic Trial of CS-1008 in Patients With Metastatic Colorectal Cancer

PURPOSE

CS-1008 (tigatuzumab) is a humanized, monoclonal immunoglobulin G1 (IgG1) agonistic antibody to human death receptor 5. The purpose of this study was to investigate the impact of CS-1008 dose on the biodistribution, quantitative tumor uptake, and antitumor response in patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Patients with mCRC who had received at least one course of chemotherapy were assigned to one of five dosage cohorts and infused with a weekly dose of CS-1008. Day 1 and day 36 doses were trace-labeled with indium-111 ((111)In), followed by whole-body planar and regional single-photon emission computed tomography (SPECT) imaging at several time points over the course of 10 days.

RESULTS

Nineteen patients were enrolled. (111)In-CS-1008 uptake in tumor was observed in only 12 patients (63%). (111)In-CS-1008 uptake and pharmacokinetics were not affected by dose or repeated drug administration. (111)In-CS-1008 biodistribution showed gradual blood-pool clearance and no abnormal uptake in normal tissue. No anti-CS-1008 antibody development was detected. One patient achieved partial response (3.7 months duration), eight patients had stable disease, and 10 patients had progressive disease. Clinical benefit rate (stable disease + partial response) in patients with (111)In-CS-1008 uptake in tumor was 58% versus 28% in patients with no uptake. An analysis of individual lesions showed that lesions with antibody uptake were one third as likely to progress as those without antibody uptake (P = .07). Death-receptor-5 expression in archived tumor samples did not correlate with (111)In-CS-1008 uptake (P = .5) or tumor response (P = .6).

CONCLUSION

Death-receptor-5 imaging with (111)In-CS-1008 reveals interpatient and intrapatient heterogeneity of uptake in tumor, is not dose dependent, and is predictive of clinical benefit in the treatment of patients who have mCRC.

Targeted chemoradiation in metastatic colorectal cancer: a phase I trial of 131I-huA33 with concurrent capecitabine

huA33 is a humanized antibody that targets the A33 antigen, which is highly expressed in intestinal epithelium and more than 95% of human colon cancers but not other normal tissues. Previous studies have shown huA33 can target and be retained in a metastatic tumor for 6 wk but eliminated from normal colonocytes within days. This phase I study used radiolabeled huA33 in combination with capecitabine to target chemoradiation to metastatic colorectal cancer. The primary objective was safety and tolerability of the combination of capecitabine and (131)I-huA33. Pharmacokinetics, biodistribution, immunogenicity, and tumor response were also assessed.

METHODS

Eligibility included measurable metastatic colorectal cancer, adequate hematologic and biochemical function, and informed consent. An outpatient scout (131)I-huA33 dose was followed by a single-therapy infusion 1 wk later, when capecitabine was commenced. Dose escalation occurred over 5 dose levels. Patients were evaluated weekly, with tumor response assessment at the end of the 12-wk trial. Tumor targeting was assessed using a γ camera and SPECT imaging.

RESULTS

Nineteen eligible patients were enrolled. The most frequently observed toxicity included myelosuppression, gastrointestinal symptoms, and asymptomatic hyperbilirubinemia. Biodistribution analysis demonstrated excellent tumor targeting of the known tumor sites, expected transient bowel uptake, but no other normal tissue uptake. (131)I-huA33 demonstrated a mean terminal half-life and serum clearance suited to radioimmunotherapy (T1/2β, 100.24 ± 20.92 h, and clearance, 36.72 ± 8.01 mL/h). The mean total tumor dose was 13.8 ± 7.6 Gy (range, 5.1-26.9 Gy). One patient had a partial response, and 10 patients had stable disease.

CONCLUSION

(131)I-huA33 achieves specific targeting of radiotherapy to colorectal cancer metastases and can be safely combined with chemotherapy, providing an opportunity to deliver chemoradiation specifically to metastatic disease in colorectal cancer patients.

Job strain and self-reported health among working women and men: an analysis of the 1994/5 Canadian National Population Health Survey

This paper explores the associations, for working women and men, of high strain jobs with self-rated health in the 1994/95 Canadian National Population Health Survey (NPHS). NPHS data were obtained on men (n = 4230) and women (n = 4043), aged 18-64 who answered an abbreviated version oF the job content questionnaire (JCQ). Using the upper and lower tertiles of psychological demands and decision latitude as cut points we classified workers into high strain and other jobs. Self-rated health was the outcome. We used polytomous logistic regression analyses and controlled for potential personal and home confounders; two risk parameters were estimated: for the odds of reporting poor/fair and good health both vs. very good/excellent health. High strain work was reported by 11% of women and 9% of men. After adjusting for potential confounders, high job strain was consistently associated with worse self-rated health in both models for each gender.

And a doctor shall lead them

With managed care reshaping every aspect of health care, physicians need to assume leadership roles more than ever before. This requires skills they don't teach in medical school.

The mercury emergency and Hamilton school children: a follow-up analysis

In September 1993, children broke into a laboratory in an abandoned scrap metal recycling plant in Hamilton and removed mercury and other materials from the site. They began distribution of the mercury to their peers but this activity was halted once an emergency response was established. This paper focuses on the identification and assessment of children exposed to mercury and the use of Epi Info 6 in the analysis. Approximately 6,000 children were screened and 269 children identified as being exposed or at risk of exposure. We found that distribution of mercury within the school system was swift. Children exhibited a number of risky behaviours with mercury. There were no significant gender differences in these behaviours. The majority of children involved were 10 to 13 years of age. No child exhibited health effects from exposure.

A review of the epidemiology, public health importance, treatment and control of head lice

Head lice are cosmopolitan and endemic. While they are not responsible for the spread of any disease, they are the cause of considerable social distress. They can infest anybody and do not discriminate between class or cleanliness. Head lice are transmitted primarily by direct contact. The only satisfactory method to clear an infestation is by chemical treatment. The most effective pediculicides to date are those which contain permethrin (Nix) or malathion (Prioderm). Compliance with product instructions eliminates the need for nit removal after treatment. Treatment of inanimate objects and the environment should be discouraged. To obtain effective control of head lice, the whole community needs to be involved. Parents must be encouraged to screen themselves and their children regularly in the home, and to treat themselves only when necessary.

Plasmacytoma of the stomach: diagnosis with the aid of immunoperoxidase technique

A gastric tumor, originally diagnosed as a plamacytoma in 1953, but in which the diagnosis was disputed, has been re-examined by the immunoperoxidase staining technique. The demonstration of a single type of immunoglobulin in the tumor cells is considered conclusive evidence of its neoplastic nature. Two further cases of gastrict plasmacytoma encountered in recent months have also been examined by this technique and similar results obtained. The pathology of plasma cell tumors is discussed and a brief review of the literature is added with regard to the management and the overall poor prognosis.