18F-Fluciclovine (18F-FACBC) PET imaging of recurrent brain tumors

PURPOSE

The aim of our study was to investigate the efficacy of 18F-Fluciclovine brain PET imaging in recurrent gliomas, and to compare the utility of these images to that of contrast enhanced magnetic resonance imaging (MRI) and to [11C-methyl]-L-methionine (11C-Methionine) PET imaging. We also sought to gain insight into the factors affecting the uptake of 18F-FACBC in both tumors and normal brain, and specifically to evaluate how the uptake in these tissues varied over an extended period of time post injection.

METHODS

Twenty-seven patients with recurrent or progressive primary brain tumor (based on clinical and MRI/CT data) were studied using dynamic 18F-Fluciclovine brain imaging for up to 4 h. Of these, 16 patients also had 11C-Methionine brain scans. Visual findings, semi-quantitative analyses and pharmacokinetic modeling of a subset of the 18F-Fluciclovine images was conducted. The information derived from these analyses were compared to data from 11C-Methionine and to contrast-enhanced MRI.

RESULTS

18F-Fluciclovine was positive for all 27 patients, whereas contrast MRI was indeterminate for three patients. Tumor 18F-Fluciclovine SUVmax ranged from 1.5 to 10.5 (average: 4.5 ± 2.3), while 11C-Methionine's tumor SUVmax ranged from 2.2 to 10.2 (average: 5.0 ± 2.2). Image contrast was higher with 18F-Fluciclovine compared to 11C-Methionine (p < 0.0001). This was due to 18F-Fluciclovine's lower background in normal brain tissue (0.5 ± 0.2 compared to 1.3 ± 0.4 for 11C-Methionine). 18F-Fluciclovine uptake in both normal brain and tumors was well described by a simple one-compartment (three-parameter: Vb,k1,k2) model. Normal brain was found to approach transient equilibrium with a half-time that varied greatly, ranging from 1.5 to 8.3 h (mean 2.7 ± 2.3 h), and achieving a consistent final distribution volume averaging 1.4 ± 0.2 ml/cc. Tumors equilibrated more rapidly (t1/2ranging from 4 to 148 min, average 57 ± 51 min), with an average distribution volume of 3.2 ± 1.1 ml/cc. A qualitative comparison showed that the rate of normal brain uptake of 11C-Methionine was much faster than that of 18F-Fluciclovine.

CONCLUSION

Tumor uptake of 18F-Fluciclovine correlated well with the established brain tumor imaging agent 11C-Methionine but provided significantly higher image contrast. 18F-Fluciclovine may be particularly useful when the contrast MRI is non-diagnostic. Based on the data gathered, we were unable to determine whether Fluciclovine uptake was due solely to recurrent tumor or if inflammation or other processes also contributed.

Identifying hospital-acquired infections using retrospective record review from the Irish National Adverse Events Study (INAES) and European point prevalence survey case definitions

BACKGROUND

Point prevalence surveys (PPSs) collect data on hospital-acquired infections (HAIs) at one point in time but do not provide information on incidence over the entire admission or impact on patients or healthcare resources. Retrospective record review examines the entire admission to determine adverse event prevalence, incidence, preventability, physical impairment and additional length of stay.

AIM

To establish whether European HAI surveillance definitions can be applied to the Irish National Adverse Events Study (INAES) retrospective record review data to determine HAI burden.

METHODS

In the INAES, 1574 admissions were reviewed using a two-stage methodology and 247 adverse events were found. These were examined against European HAI case definitions to determine whether the event was an HAI. Results were compared with the 2011/12 European PPS data for Ireland.

FINDINGS

The prevalence of HAI adverse events in INAES was 4.4% (95% confidence interval (CI) 3.1-6.1%) with an incidence of 3.8 (95% CI 2.5-5.2) HAI adverse events per 100 admissions. The PPS HAI prevalence for Ireland was 5.2%. HAI types and micro-organisms were similar in INAES and the PPS. Approximately three-quarters of INAES HAI adverse events were preventable, 7% caused permanent impairment and 7% contributed to death. A mean of 10 additional bed days were attributed to HAI adverse events, equivalent to €9400 per event.

CONCLUSION

Retrospective record review is an accurate source of information on HAI incidence, preventability and impact that complements PPS prevalence rates. HAI adverse events result in higher costs to the healthcare system than other adverse events.

Strain-specific differences in brain gene expression in a hydrocephalic mouse model with motile cilia dysfunction

Congenital hydrocephalus results from cerebrospinal fluid accumulation in the ventricles of the brain and causes severe neurological damage, but the underlying causes are not well understood. It is associated with several syndromes, including primary ciliary dyskinesia (PCD), which is caused by dysfunction of motile cilia. We previously demonstrated that mouse models of PCD lacking ciliary proteins CFAP221, CFAP54 and SPEF2 all have hydrocephalus with a strain-dependent severity. While morphological defects are more severe on the C57BL/6J (B6) background than 129S6/SvEvTac (129), cerebrospinal fluid flow is perturbed on both backgrounds, suggesting that abnormal cilia-driven flow is not the only factor underlying the hydrocephalus phenotype. Here, we performed a microarray analysis on brains from wild type and nm1054 mice lacking CFAP221 on the B6 and 129 backgrounds. Expression differences were observed for a number of genes that cluster into distinct groups based on expression pattern and biological function, many of them implicated in cellular and biochemical processes essential for proper brain development. These include genes known to be functionally relevant to congenital hydrocephalus, as well as formation and function of both motile and sensory cilia. Identification of these genes provides important clues to mechanisms underlying congenital hydrocephalus severity.

Abstract P5-19-01: Impact of palbociclib plus letrozole on patient-reported general health status compared with letrozole alone in ER+/HER2- advanced/metastatic breast cancer

BACKGROUND: Palbociclib plus letrozole significantly improved progression-free survival (PFS) compared with letrozole plus placebo in treatment-naive postmenopausal patients with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC) in the phase 3 PALOMA-2 trial. Here, we compare patient-reported general health status with extended (max 53 cycles) follow-up (data cut off May31st, 2017) (Pfizer: NCT01740427).

METHODS: PALOMA-2 randomized patients 2:1 to palbociclib + letrozole (n=444) or placebo + letrozole (n=222). Patient-reported outcomes were assessed at baseline, day 1 of cycles 1, 2, and 3, and day 1 of every other cycle from cycle 5 until the end of treatment using the EuroQol 5-Dimension Questionnaire (EQ-5D). The EQ-5D is a standardized measure of health status that consists of a descriptive system comprising the following 5 dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression rated at 3 levels (no, some, or extreme problems) and a single index score for health status (ranges generally from 0 [dead] to 1 [full health]) calculated using a standard algorithm. In addition, a visual analog scale (VAS) measured self-rated health status from 0 (worst imaginable) to 100 (best imaginable). Repeated measures mixed-effects analyses were performed to compare overall index and VAS scores between treatments, controlling for baseline.

RESULTS: Completion rates at baseline were &gt;95% in each group. The mean (SD) scores at baseline were comparable between palbociclib plus letrozole and letrozole alone for the VAS (71.3 [21.2] vs 72.3 [19.8]) and the EQ-5D index scores (0.70 [0.25]) vs (0.73 [0.21]). Median follow up was 38 months for palbociclib plus letrozole and 37 months for letrozole only. No statistically significant difference in overall change from baseline in general health status was observed between the treatment arms. The proportion of patients reporting the presence of a problem at baseline was similar for palbociclib plus letrozole and letrozole, respectively: mobility (39% vs 39%), self-care (12% vs 12%), usual activities (44% vs 39%), pain (69% vs 65%), and anxiety/depression (54% vs 54%). No statistically significant difference in overall mean EQ-5D index scores (0.73 vs. 0.71) was observed between the treatment arms.

CONCLUSION: Addition of palbociclib to letrozole maintained general health status and EQ-5D index scores in ER+ HER2- advanced/metastatic breast cancer with no statistically significant differences observed compared to letrozole alone.

Citation Format: Harbeck N, Dieras V, Finn R, Gelmon KA, Walshe JM, Shparyk Y, Mori A, Lui DR, Bhattacharyya H, Iyer S, Johnston S, Rugo HS. Impact of palbociclib plus letrozole on patient-reported general health status compared with letrozole alone in ER+/HER2- advanced/metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-19-01.

Abstract MS1-2: Targeting CDK 4/6 in breast cancer

For decades, cyclin-dependent kianses (CDKs) have been known to be critical regulators of cell cycle progression leading to the Nobel Prize in 2001 for their identification and characterization. Subsequently, alteration in these and associated proteins have been implicated in cancer. In breast cancer, they have been associated with various molecular subtypes, prognosis, and response to therapy. The concept of blocking CDKs has been around for some time but only recently have they seen clinical success. First generation CDK inhibitors did not demonstrate significant clinical activity and had unacceptable toxicity. In addition to having an appropriate compound, as with other molecular targeted agents, identification of a patient population most likely to benefit is critical to successful clinical development. Palbociclib (PD-0332991, Pfizer) is a first-in-class CDK 4/6 specific inhibitor. Pre-clinical studies identified that ER+ breast cancer models were most sensitive to growth inhibition with palbociclib and identified a synergistic interaction in inhibiting proliferation in combination with anti-estrogens (Finn et al 2009). These data served as a hypotheses for the Phase II Paloma-1/ TRIO 18 study of palbociclib +letrozole vs letrozole alone (Finn et al Lancet Oncolog 2015). Results of this study demonstrated a significant improvement in PFS with the combination and served as the basis for the expedited approval of palbociclib +letrozole as first line therapy for advanced post-menopausal ER+ breast cancer. Most common toxicities were neutropenia, leukopenia and fatigue. Subsequently, a consistent benefit was seen in combination with fulvestrant in more advanced settings (Turner et al NEJM 2015) with a similar toxicity profile. Currently there are several other CDK 4/6 inhibitors in development in breast cancer and other malignancies including abemaciclib (LY2835219, EliLilly) and ribociclib (LEE011, Novartis). In the presentation we will review the rationale for CDK 4/6 inhibition in breast cancer as well as clinical efficacy and toxicity data and the ongoing development of this new class of agent in breast cancer.

Citation Format: Finn R. Targeting CDK 4/6 in breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr MS1-2.

CFAP54 is required for proper ciliary motility and assembly of the central pair apparatus in mice

Motile cilia and flagella play critical roles in fluid clearance and cell motility, and dysfunction commonly results in the pediatric syndrome primary ciliary dyskinesia (PCD). CFAP221, also known as PCDP1, is required for ciliary and flagellar function in mice and Chlamydomonas reinhardtii, where it localizes to the C1d projection of the central microtubule apparatus and functions in a complex that regulates flagellar motility in a calcium-dependent manner. We demonstrate that the genes encoding the mouse homologues of the other C. reinhardtii C1d complex members are primarily expressed in motile ciliated tissues, suggesting a conserved function in mammalian motile cilia. The requirement for one of these C1d complex members, CFAP54, was identified in a mouse line with a gene-trapped allele. Homozygous mice have PCD characterized by hydrocephalus, male infertility, and mucus accumulation. The infertility results from defects in spermatogenesis. Motile cilia have a structural defect in the C1d projection, indicating that the C1d assembly mechanism requires CFAP54. This structural defect results in decreased ciliary beat frequency and perturbed cilia-driven flow. This study identifies a critical role for CFAP54 in proper assembly and function of mammalian cilia and flagella and establishes the gene-trapped allele as a new model of PCD.

Strain-dependent brain defects in mouse models of primary ciliary dyskinesia with mutations in Pcdp1 and Spef2

Hydrocephalus is caused by the accumulation of cerebrospinal fluid (CSF) in the cerebral ventricular system which results in an enlargement of the cranium due to increased intraventricular pressure. The increase in pressure within the brain typically results in sloughing of ciliated ependymal cells, loss of cortical gray matter, and increased gliosis. Congenital hydrocephalus is associated with several syndromes including primary ciliary dyskinesia (PCD), a rare, genetically heterogeneous, pediatric syndrome that results from defects in motile cilia and flagella. We have examined the morphological and physiological defects in the brains of two mouse models of PCD, nm1054 and bgh, which have mutations in Pcdp1 (also known as Cfap221) and Spef2, respectively. Histopathological and immunohistochemical analyses of mice with these mutations on the C57BL/6J and 129S6/SvEvTac genetic backgrounds demonstrate strain-dependent morphological brain damage. Alterations in astrocytosis, microglial activation, myelination, and the neuronal population were identified and are generally more severe on the C57BL/6J background. Analysis of ependymal ciliary clearance ex vivo and CSF flow in vivo demonstrate a physiological defect in nm1054 and bgh mice on both genetic backgrounds, indicating that abnormal cilia-driven flow is not the sole determinant of the severity of hydrocephalus in these models. These results suggest that genetic modifiers play an important role in susceptibility to severe PCD-associated hydrocephalus.

Treatment of the Ppt1(-/-) mouse model of infantile neuronal ceroid lipofuscinosis with the N-methyl-D-aspartate (NMDA) receptor antagonist memantine

The neuronal ceroid lipofuscinoses, a family of neurodegenerative lysosomal storage disorders, represent the most common cause of pediatric-onset neurodegeneration. The infantile form has a devastatingly early onset and one of the fastest-progressing disease courses. Despite decades of research, the molecular mechanisms driving neuronal loss in infantile neuronal ceroid lipofuscinosis remain unknown. We have previously shown that N-methyl-d-aspartate (NMDA)-type glutamate receptors in the Ppt1(-/-) mouse model of this disease exhibit a hyperfunctional phenotype and postulate that aberrant glutamatergic activity may contribute to neural pathology in both the mouse model and human patients. To test this hypothesis, we treated Ppt1(-/-) mice with the NMDA receptor antagonist memantine and assessed their response to the drug using an accelerating rotarod. At 20 mg/kg, memantine treatment induced a delayed but notable improvement in Ppt1(-/-) mice. Much remains to be assessed before moving to patient trials, but these results suggest memantine has potential as a treatment.

Altered glutamate receptor function in the cerebellum of the Ppt1-/- mouse, a murine model of infantile neuronal ceroid lipofuscinosis

The neuronal ceroid lipofuscinoses (NCLs) are a family of devastating pediatric neurodegenerative disorders and currently represent the most common form of pediatric-onset neurodegeneration. Infantile NCL (INCL), the most aggressive of these disorders, is caused by mutations in the CLN1 gene that encodes the enzyme palmitoyl protein thioesterase 1 (PPT1). Previous studies have suggested that glutamatergic neurotransmission may be disrupted in INCL, so the present study investigates glutamate receptor function in the Ppt1(-/-) mouse model of INCL by comparing the sensitivity of cultured wild-type (WT) and Ppt1(-/-) cerebellar granule cells to glutamate receptor-mediated toxicity. Ppt1(-/-) neurons were significantly less sensitive to AMPA receptor-mediated toxicity but markedly more vulnerable to NMDA receptor-mediated cell death. Because glutamate receptor function is regulated primarily by the surface expression level of the receptor, the surface level of AMPA and NMDA receptor subunits in the cerebella of WT and Ppt1(-/-) mice was also examined. Western blotting of surface cross-linked cerebellar samples showed a significantly lower surface level of the GluR4 AMPA receptor subunit in Ppt1(-/-) mice, providing a plausible explanation for the decreased vulnerability of Ppt1(-/-) cerebellar neurons to AMPA receptor-mediated cell death. The surface expression of the NR1, NR2A, and NR2B NMDA receptor subunits was similar in the cerebella of WT and Ppt1(-/-) mice, indicating that there is another mechanism behind the increased sensitivity of Ppt1(-/-) cerebellar granule cells to NMDA toxicity. Our results indicate an AMPA receptor hypofunction and NMDA receptor hyperfunction phenotype in Ppt1(-/-) neurons and provide new therapeutic targets for INCL.

Association between Previous Tuberculous Infection and Cerebal Glioma

An increased incidence of previous infection with tuberculosis has been found in a series of patients with cerebral gliomas, and it is suggested that such an association may be due to defective immunity acting as a common aetiological factor.

Altered sensitivity to excitotoxic cell death and glutamate receptor expression between two commonly studied mouse strains

Alterations in glutamatergic synapse function have been implicated in the pathogenesis of many different neurological disorders, including ischemia, epilepsy, Parkinson's disease, Alzheimer's disease, and Huntington's disease. While studying glutamate receptor function in juvenile Batten disease on the C57BL/6J and 129S6/S(v)E(v) mouse backgrounds, we noticed differences unlikely to be due to mutation difference alone. We report here that primary cerebellar granule cell cultures from C57BL/6J mice are more sensitive to N-methyl-D-aspartate (NMDA)-mediated cell death. Moreover, sensitivity to AMPA-mediated excitotoxicity is more variable and is dependent on the treatment conditions and age of the cultures. Glutamate receptor surface expression levels examined in vitro by in situ ELISA and in vivo by Western blot in surface cross-linked cerebellar samples indicated that these differences in sensitivity likely are due to strain-dependent differences in cell surface receptor expression levels. We propose that differences in glutamate receptor expression and in excitotoxic vulnerability should be taken into consideration in the context of characterizing disease models on the C57BL/6J and 129S6/S(v)E(v) mouse backgrounds.

Abstract P3-10-24: Fibroblast Growth Factor Receptor 1 Amplification and Overexpression in Breast Cancer Tissue Microarrays Using Chromogenic In Situ Hybridization and Immunohistochemistry

Fibroblast growth factor receptors 1 (FGFR1) belongs to a subfamily of receptor tyrosine kinases (RTKs), which are involved in proliferation and apoptosis. FGFR1 amplification and mRNA overexpression occurs in ∼10% of breast cancers and has been associated with poor outcome. However, studies assessing FGFR1 amplification and protein overexpression in a large collection of breast tumors are lacking. In this prospective, we examined a series of primary breast cancers samples derived from the BCIRG trials assembled into 15 tissue microarrays. FGFR1 gene amplification was studied using chromogenic in situ hybridization (CISH) and evaluated with respect to association with level of protein expression and clinicopathological parameters. FGFR1 gene amplification was significantly associated with high protein levels as determined by immunohistochemistry (P&lt;0.0001, 3294 pts with available matched CISH and IHC records). Overall, the incidence of FGFR1 amplification found was 9.7% (160 out of 1646 pts. with available clinicopathological records) without a statistically significant difference between Her2- (78 out 720 pts., 11%) and Her2+ (82 out of 926 pts., 9%) cancers. In both cohorts, the hormone receptor-positive (ER+/PR+) cancers showed statistically significant higher levels of FGFR1 amplification compared to hormone receptor-negative tumors. In the analysis of the association of FGFR1 and the presence of PIK3CA mutations, the incidence of FGFR1 amplificationwas greatly reduced in mutant vs. wt PI3KCA tumors. In these cohorts, a clear relationship between FGFR1 amplification status and clinical outcome was not detected. Data from this large study confirms recently reported incidences of FGFR1 amplification in breast cancer and shows for the first time an association between FGFR1 gene amplification and protein overexpression. Moreover, the lower incidence of FGFR1 amplification in PIK3CA mutated cancers suggests that these are largely exclusive molecular events that could benefit from different targeted therapies.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-10-24.

On the behavior of a capillary surface in a wedge

Estimates above and below are obtained for the height of the equilibrium-free surface of a liquid when the liquid partially fills a cylindrical container whose cross section contains a corner with interior angle 2alpha. The surface is characterized by the condition that its mean curvature be proportional to its height above a reference plane (or, in the case of zero gravity, that the mean curvature be constant), and by the requirement that it meet the container wall with prescribed contact angle gamma. It turns out that the qualitative behavior of such a surface near the vertex changes markedly, according as alpha + gamma < (1/2)pi, or alpha + gamma >/= (1/2)pi. In the former case, the surface is either unbounded or fails to exist, while in the latter case every such surface is bounded. Some experimental comparisons are indicated, and an application to the problem of describing the mechanism of water rise in trees is discussed.The above results describe a limiting case among corresponding properties that hold for surfaces defined over domains with smooth boundaries. This extension is indicated, as well as a formal extension to n-dimensional surfaces; here the interest centers on the fact that it is the mean curvature of an (n-1)-dimensional boundary element that controls the local behavior of the n-dimensional solution surface.

PI3 Kinase Pathway Analysis in Tissue Microarrays Using Laser Capture Microdissection and Immunohistochemistry

Background. During the performance of the BCIRG trials primary patient tumor samples were obtained from paraffin blocks and assembled into 15 tissue microarrays, including 3000 samples from trial 005 (adjuvant taxol in Her2- node positive patients), 2200 in 006 (adjuvant herceptin in Her2+ high risk patients) and 300 in 007 (addition of platinum in Her2+ first line therapy). This array set was prepared prospectively, in anticipation of molecular epidemiologic studies of a variety of targets in relation to outcome. In order to address the potentially important role of the PIK3CA pathway in modulating outcome in different clinical situations we assessed components of the PIK3CA pathway by various methods.Methods. We analysed the expression of PTEN, Cyclin D1, p53 and Stathmin by immunohistochemistry using standard methods. All markers were scored by histoscore. Phospho S6 240 and phospho Akt 473 were assessed simultaneously by quantum dot immunofluorescence using automated image capture and segmentation. PIK3CA mutations were evaluated using SnaPshot analysis of laser captured TMA spots in a subset of approximately 2000 samples.Results. In the samples analyzed PIK3CA mutation had an incidence of 23%, with 9% being mutations in exon 9 and 13% in exon 20, with 0.5% being mutant in both exons. Initial analysis of the results prior to outcome analysis indicated that Stathmin expression, while being a robust marker with good dynamic range, did not appear to correlate with PTEN loss by IHC or with PIK3CA mutation.Conclusions. PIK3CA mutational analysis is feasible from TMA cores and gives mutation incidences similar to the published literature for archival material. Relationships of markers with outcome will be presented.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4043.

Molecular imaging of EGFR kinase activity in tumors with 124I-labeled small molecular tracer and positron emission tomography

Positron emission tomography (PET) with epidermal growth factor receptor (EGFR) kinase-specific radiolabeled tracers could provide the means for noninvasive and repetitive imaging of heterogeneity of EGFR expression and signaling activity in tumors in individual patients before and during therapy with EGFR signaling inhibitors. We developed the synthesis and (124)I-radiolabeling of the (E)-But-2-enedioic acid [4-(3-[(124)I]iodoanilino)-quinazolin-6-yl]-amide-(3-morpholin-4-yl-propyl)-amide (morpholino-[(124)I]-IPQA), which selectively, irreversibly, and covalently binds the adenosine-triphosphate-binding site to the activated (phosphorylated) EGFR kinase, but not to the inactive EGFR kinase. The latter was demonstrated using in silico modeling with crystal structures of the wild type and different gain-of-function mutants of EGFR kinases. Also, this was demonstrated by selective radiolabeling of the EGFR kinase domain with morpholino-[(131)I]-IPQA in A431 human epidermoid carcinoma cells and Western blot autoradiography. In vitro radiotracer accumulation and washout studies demonstrated a rapid accumulation and progressive retention postwashout of morpholino-[(131)I]-IPQA in A431 epidermoid carcinoma and in U87 human glioma cells genetically modified to express the EGFRvIII mutant receptor, but not in the wild-type U87MG glioma cells under serum-starved conditions. Using morpholino-[(124)I]-IPQA, we obtained noninvasive PET images of EGFR activity in A431 subcutaneous tumor xenografts, but not in subcutaneous tumor xenografts grown from K562 human chronic myeloid leukemia cells in immunocompromised rats and mice. Based on these observations, we suggest that PET imaging with morpholino-[(124)I]-IPQA should allow for identification of tumors with high EGFR kinase signaling activity, including brain tumors expressing EGFRvIII mutants and nonsmall-cell lung cancer expressing gain-of-function EGFR kinase mutants. Because of significant hepatobiliary clearance and intestinal reuptake of the morpholino-[(124)I]-IPQA, additional [(124)I]-IPQA derivatives with improved water solubility may be required to optimize the pharmacokinetics of this class of molecular imaging agents.

Targeting Lewis Y (LeY) in small cell lung cancer (SCLC) with a humanized monoclonal antibody, hu3S193

7086

Background: LeY is a blood group antigen with dominant expression on the surface of epithelial tumors, including SCLC, making it a potential target for antibody-based immunotherapy. 3S193, an IgG3 mAb, has demonstrated superior specificity, affinity, and cytotoxicity over other anti-LeY antibodies. A phase I trial of humanized 3S193 (hu3S193) with dosing up to 40 mg/m2 demonstrated tumor targeting without serious toxicities or the development of human antihuman antibodies (Scott et al, ASCO, 2004). Methods: We tested the targeting and pharmacokinetics of hu3S193 in patients with SCLC. Eligibility required progressive SCLC treated with up to three prior chemotherapy regimens, measurable disease not previously irradiated, and tumor samples immunohistochemistry (IHC)-positive for 3S193. Patients received four weekly injections of hu3S193, 5 patients at 10mg/m2 and 5 patients at 20 mg/m2. The first and fourth injections were radiolabeled with 111Indium for gamma camera imaging. Results: Of 40 patients screened, 25/34 (74%) evaluable SCLC tumor samples were 3S193-positive by IHC: 1+ (n = 13), 2+ (n = 3), 3+ (n = 2), 4+ (n = 7). Ten patients were treated with hu3S193; eight completed all four injections (one had disease progression and one is still on treatment). At the lower dose, about 50% of lesions >2 cm diameter visualized on FDG-PET were also seen on 111In SPECT imaging. However, at the higher dose, essentially all FDG avid lesions showed targeting. The mean T1/2 for all infusions was 2.89 ± 0.84 days at 10 mg/m2 (n = 9) and 3.29 ± 0.66 days at 20 mg/m2 (n = 7). No difference was noted in imaging or pharmacokinetics between the first and fourth injections. At the 20 mg/m2 dose, patients experienced grade 2 urticaria (n = 1), grade 1 vomiting (n = 2), and grade 2 hypertension (n = 1) transiently after infusion. No other grade 2 or greater toxicities were observed. No objective responses were observed. Conclusions: SCLC has a high rate of Lewis Y expression. Given the strong tumor targeting, particularly at the higher dose, and the potential for immunomodulatory effects, administration of hu3S193 with chemotherapy would be warranted. Supported by the Ludwig Institute and the Experimental Therapeutics Committee of MSKCC.

No significant financial relationships to disclose.