Spatial transcriptomics reveals discrete tumour microenvironments and autocrine loops within ovarian cancer subclones.

High-grade serous ovarian carcinoma (HGSOC) is genetically unstable and characterised by the presence of subclones with distinct genotypes. Intratumoural heterogeneity is linked to recurrence, chemotherapy resistance, and poor prognosis. Here, we use spatial transcriptomics to identify HGSOC subclones and study their association with infiltrating cell populations. Visium spatial transcriptomics reveals multiple tumour subclones with different copy number alterations present within individual tumour sections. These subclones differentially express various ligands and receptors and are predicted to differentially associate with different stromal and immune cell populations. In one sample, CosMx single molecule imaging reveals subclones differentially associating with immune cell populations, fibroblasts, and endothelial cells. Cell-to-cell communication analysis identifies subclone-specific signalling to stromal and immune cells and multiple subclone-specific autocrine loops. Our study highlights the high degree of subclonal heterogeneity in HGSOC and suggests that subclone-specific ligand and receptor expression patterns likely modulate how HGSOC cells interact with their local microenvironment.

Drug-regulated CD33-targeted CAR T cells control AML using clinically optimized rapamycin dosing.

Chimeric antigen receptor (CAR) designs that incorporate pharmacologic control are desirable; however, designs suitable for clinical translation are needed. We designed a fully human, rapamycin-regulated drug product for targeting CD33+ tumors called dimerizaing agent-regulated immunoreceptor complex (DARIC33). T cell products demonstrated target-specific and rapamycin-dependent cytokine release, transcriptional responses, cytotoxicity, and in vivo antileukemic activity in the presence of as little as 1 nM rapamycin. Rapamycin withdrawal paused DARIC33-stimulated T cell effector functions, which were restored following reexposure to rapamycin, demonstrating reversible effector function control. While rapamycin-regulated DARIC33 T cells were highly sensitive to target antigen, CD34+ stem cell colony-forming capacity was not impacted. We benchmarked DARIC33 potency relative to CD19 CAR T cells to estimate a T cell dose for clinical testing. In addition, we integrated in vitro and preclinical in vivo drug concentration thresholds for off-on state transitions, as well as murine and human rapamycin pharmacokinetics, to estimate a clinically applicable rapamycin dosing schedule. A phase I DARIC33 trial has been initiated (PLAT-08, NCT05105152), with initial evidence of rapamycin-regulated T cell activation and antitumor impact. Our findings provide evidence that the DARIC platform exhibits sensitive regulation and potency needed for clinical application to other important immunotherapy targets.

TRACEBACK: Testing of Historical Tubo-Ovarian Cancer Patients for Hereditary Risk Genes as a Cancer Prevention Strategy in Family Members.

PURPOSE: Tubo-ovarian cancer (TOC) is a sentinel cancer for BRCA1 and BRCA2 pathogenic variants (PVs). Identification of a PV in the first member of a family at increased genetic risk (the proband) provides opportunities for cancer prevention in other at-risk family members. Although Australian testing rates are now high, PVs in patients with TOC whose diagnosis predated revised testing guidelines might have been missed. We assessed the feasibility of detecting PVs in this population to enable genetic risk reduction in relatives. PATIENTS AND METHODS: In this pilot study, deceased probands were ascertained from research cohort studies, identification by a relative, and gynecologic oncology clinics. DNA was extracted from archival tissue or stored blood for panel sequencing of 10 risk-associated genes. Testing of deceased probands ascertained through clinic records was performed with a consent waiver. RESULTS: We identified 85 PVs in 84 of 787 (11%) probands. Familial contacts of 39 of 60 (65%) deceased probands with an identified recipient (60 of 84; 71%) have received a written notification of results, with follow-up verbal contact made in 85% (33 of 39). A minority of families (n = 4) were already aware of the PV. For many (29 of 33; 88%), the genetic result provided new information and referral to a genetic service was accepted in most cases (66%; 19 of 29). Those who declined referral (4 of 29) were all male next of kin whose family member had died more than 10 years before. CONCLUSION: We overcame ethical and logistic challenges to demonstrate that retrospective genetic testing to identify PVs in previously untested deceased probands with TOC is feasible. Understanding reasons for a family member's decision to accept or decline a referral will be important for guiding future TRACEBACK projects.

Transcriptomic analysis of patient plasma reveals circulating miR200c as a potential biomarker for high-grade serous ovarian cancer.

BACKGROUND: High-grade serous tubo-ovarian cancer (HGSC) is the most common histological subtype of epithelial ovarian cancer, and highly lethal. Currently there is no effective screening test and prognosis is poor as the majority of cases are diagnosed at the advanced stage. Cell free RNAs including microRNAs (miRNAs) are dysregulated in ovarian cancer tissue and are detectable in the circulation. This study aimed to determine whether circulating cell free miRNAs may be potential biomarkers for the detection of HGSC. METHODS: Plasma was collected from women with HGSC (Grade 3, n = 24), and benign ovarian masses (n = 24). RNA was extracted from patient plasma and subjected to miRNA targeted next generation sequencing (NGS). A subsequent validation cohort was assessed using plasma collected from women with HGSC (n = 14) and controls (with a benign ovarian mass; n = 15). RNA was extracted and assessed using quantitative RT-PCR. RESULTS: Differential gene expression (DGE) of the NGS data revealed a significant increase in the miRNA, miR200c, in the circulation of women with HGSC (p less than 0.05) compared to controls. In the validation cohort miR200c expression by qPCR was found to also be increased in the circulation of women with HGSC compared to controls (p = 0.0023). CONCLUSIONS: Circulating miR200c may be a promising candidate biomarker for the detection of HGSC. Further larger cohort studies exploring earlier stages are needed to determine whether circulating miR200c may be a sensitive and specific biomarker of tubo-ovarian cancer.

MCM3 is a novel proliferation marker associated with longer survival for patients with tubo-ovarian high-grade serous carcinoma.

Tubo-ovarian high-grade serous carcinomas (HGSC) are highly proliferative neoplasms that generally respond well to platinum/taxane chemotherapy. We recently identified minichromosome maintenance complex component 3 (MCM3), which is involved in the initiation of DNA replication and proliferation, as a favorable prognostic marker in HGSC. Our objective was to further validate whether MCM3 mRNA expression and possibly MCM3 protein levels are associated with survival in patients with HGSC. MCM3 mRNA expression was measured using NanoString expression profiling on formalin-fixed and paraffin-embedded tissue (N = 2355 HGSC) and MCM3 protein expression was assessed by immunohistochemistry (N = 522 HGSC) and compared with Ki-67. Kaplan-Meier curves and the Cox proportional hazards model were used to estimate associations with survival. Among chemotherapy-naïve HGSC, higher MCM3 mRNA expression (one standard deviation increase in the score) was associated with longer overall survival (HR = 0.87, 95% CI 0.81-0.92, p < 0.0001, N = 1840) in multivariable analysis. MCM3 mRNA expression was highest in the HGSC C5.PRO molecular subtype, although no interaction was observed between MCM3, survival and molecular subtypes. MCM3 and Ki-67 protein levels were significantly lower after exposure to neoadjuvant chemotherapy compared to chemotherapy-naïve tumors: 37.0% versus 46.4% and 22.9% versus 34.2%, respectively. Among chemotherapy-naïve HGSC, high MCM3 protein levels were also associated with significantly longer disease-specific survival (HR = 0.52, 95% CI 0.36-0.74, p = 0.0003, N = 392) compared to cases with low MCM3 protein levels in multivariable analysis. MCM3 immunohistochemistry is a promising surrogate marker of proliferation in HGSC.

Getting the MOST out of follow-up: a randomized controlled trial comparing 3 monthly nurse led follow-up via telehealth, including monitoring CA125 and patient reported outcomes using the MOST (Measure of Ovarian Symptoms and Treatment concerns) with routine clinic based or telehealth follow-up, after completion of first line chemotherapy in patients with epithelial ovarian cancer.

BACKGROUND: Physical symptoms, anxiety, depression, fear of recurrence, sexual dysfunction, and social withdrawal are common in women after treatment for ovarian cancer. Most patients would like and need help dealing with these symptoms. The traditional model of follow-up care is unstructured and largely focused on diagnosing recurrent disease, and most oncologists lack skills to identify and manage psychosocial issues. No high quality prospective clinical trials have been conducted to determine the optimal follow-up regimen or the cost effectiveness of ovarian cancer surveillance strategies. PRIMARY OBJECTIVES: To assess emotional wellbeing, acceptability, safety, and cost effectiveness of nurse led follow-up via telehealth for women with ovarian cancer following completion of primary treatment. STUDY HYPOTHESIS: We hypothesize that compared with routine clinic based follow-up, nurse led follow-up via telehealth, including serum CA125 monitoring and completion of a patient reported outcome instrument, the Measure of Ovarian Symptoms and Treatment concerns-Surveillance (MOST-S26), will improve emotional wellbeing in women with ovarian cancer; be feasible, safe, acceptable, and not delay the time to diagnosis of recurrent disease; will result in greater patient satisfaction; will identify more patients with psychological distress, lead to better care, and improved psychological outcomes; and be cost-effective. TRIAL DESIGN: Phase II multicenter randomized trial comparing 3 monthly nurse led telehealth consultations that include serum CA125 monitoring and completion of the MOST-S26, with routine clinic based follow-up. The allocation ratio will be 1:1. MAJOR INCLUSION/EXCLUSION CRITERIA: Eligible patients will be women with high grade epithelial ovarian cancer who have normalized serum CA125 (to <35 kU/L) at completion of first line chemotherapy. PRIMARY ENDPOINTS: Emotional wellbeing at 12 months. SAMPLE SIZE: 150 patients. ESTIMATED DATES FOR COMPLETING ACCRUAL AND PRESENTING RESULTS: July 2023. Results expected in 2025, 24 months after the last participant is enrolled. TRIAL REGISTRATION: ACTRN12620000332921.

Nonclinical Development of SRK-181: An Anti-Latent TGFß1 Monoclonal Antibody for the Treatment of Locally Advanced or Metastatic Solid Tumors.

Checkpoint inhibitors offer a promising immunotherapy strategy for cancer treatment; however, due to primary or acquired resistance, many patients do not achieve lasting clinical responses. Recently, the transforming growth factor-ß (TGFß) signaling pathway has been identified as a potential target to overcome primary resistance, although the nonselective inhibition of multiple TGFß isoforms has led to dose-limiting cardiotoxicities. SRK-181 is a high-affinity, fully human antibody that selectively binds to latent TGFß1 and inhibits its activation. To support SRK-181 clinical development, we present here a comprehensive preclinical assessment of its pharmacology, pharmacokinetics, and safety across multiple species. In vitro studies showed that SRK-181 has no effect on human platelet function and does not induce cytokine release in human peripheral blood. Four-week toxicology studies with SRK-181 showed that weekly intravenous administration achieved sustained serum exposure and was well tolerated in rats and monkeys, with no treatment-related adverse findings. The no-observed-adverse-effect levels levels were 200 mg/kg in rats and 300 mg/kg in monkeys, the highest doses tested, and provide a nonclinical safety factor of up to 813-fold (based on Cmax) above the phase 1 starting dose of 80 mg every 3 weeks. In summary, the nonclinical pharmacology, pharmacokinetic, and toxicology data demonstrate that SRK-181 is a selective inhibitor of latent TGFß1 that does not produce the nonclinical toxicities associated with nonselective TGFß inhibition. These data support the initiation and safe conduct of a phase 1 trial with SRK-181 in patients with advanced cancer.

Excisional treatment comparison for in situ endocervical adenocarcinoma (EXCISE): A phase 2 pilot randomized controlled trial to compare histopathological margin status, specimen size and fragmentation after loop electrosurgical excision procedure and cold knife cone biopsy.

OBJECTIVE: Adenocarcinoma in situ (AIS) of the cervix is a precursor to cervical adenocarcinoma. When AIS is detected by cervical screening an excision biopsy is mandatory to exclude invasion. We aimed to compare margins status, specimen size and fragmentation after loop electrosurgical excision procedure (LEEP) and 'cold knife cone biopsy' (CKC). METHODS: The EXCISE Trial was an investigator-initiated, multicenter, open-label, parallel-group, phase 2, randomized study. Patients were enrolled at seven hospitals in Australia and New Zealand. We randomly assigned women aged ≥18 to ≤45 years with screen detected AIS to LEEP or CKC. Co-primary endpoints were margin status, specimen size and fragmentation. Analysis was by intention-to-treat. RESULTS: Between August 2, 2017 and September 6, 2019, 40 patients were randomly assigned 2:1 to LEEP or CKC. Margin status was evaluable in 36 cases. The proportion of patients with involved margins did not differ between groups. 25 of 26 LEEP and all 14 CKC biopsies were excised as single specimens (p = 1·00). There were no differences in specimen dimensions. Patients in the CKC group had more post-operative complications (64.3% compared to 15.4% for LEEP p = ·00). There were no differences in grade three complications (p = ·65). CONCLUSIONS: LEEP was not associated with a greater likelihood of positive margins, specimen fragmentation or smaller excision compared to CKC when performed according to a standardized protocol. However, the study was not powered to establish non-inferiority of LEEP and a definitive phase 3 trial to compare margin status and rates of treatment failure after LEEP and CKC is warranted.

A combination of the immunohistochemical markers CK7 and SATB2 is highly sensitive and specific for distinguishing primary ovarian mucinous tumors from colorectal and appendiceal metastases.

Primary ovarian mucinous tumors can be difficult to distinguish from metastatic gastrointestinal neoplasms by histology alone. The expected immunoprofile of a suspected metastatic lower gastrointestinal tumor is CK7-/CK20+/CDX2+/PAX8-. This study assesses the addition of a novel marker SATB2, to improve the diagnostic algorithm. A test cohort included 155 ovarian mucinous tumors (105 carcinomas and 50 borderline tumors) and 230 primary lower gastrointestinal neoplasms (123 colorectal adenocarcinomas and 107 appendiceal neoplasms). All cases were assessed for SATB2, PAX8 CK7, CK20, and CDX2 expression on tissue microarrays. Expression was scored in a 3-tier system as absent, focal (1-50% of tumor cells) and diffuse ( >50% of tumor cells) and then categorized into either absent/present or nondiffuse/diffuse. SATB2 and PAX8 expression was further evaluated in ovarian tumors from an international cohort of 2876 patients (expansion cohort, including 159 mucinous carcinomas and 46 borderline mucinous tumors). The highest accuracy of an individual marker in distinguishing lower gastrointestinal from ovarian mucinous tumors was CK7 (91.7%, nondiffuse/diffuse cut-off) followed by SATB2 (88.8%, present/absent cut-off). The most effective combination was CK7 and SATB2 with accuracy of 95.3% using the 3-tier interpretation, absent/focal/diffuse. This combination outperformed the standard clinical set of CK7, CK20 and CDX2 (87.5%). Re-evaluation of outlier cases confirmed ovarian origin for all but one case. The accuracy of SATB2 was confirmed in the expansion cohort (91.5%). SATB2 expression was also detected in 15% of ovarian endometrioid carcinoma but less than 5% of other ovarian histotypes. A simple two marker combination of CK7 and SATB2 can distinguish lower gastrointestinal from ovarian primary mucinous tumors with greater than 95% accuracy. PAX8 and CDX2 have value as second-line markers. The utility of CK20 in this setting is low and this warrants replacement of this marker with SATB2 in clinical practice.

Clinical Pharmacology Tools and Evaluations to Facilitate Comprehensive Dose Finding in Oncology: A Continuous Risk-Benefit Approach.

Targeted therapies are now considered an integral component in the treatment armamentarium for many malignancies, and the approach to developing these drugs needs to be refined from the previous cytotoxic paradigm of toxicity-guided dose finding and identification of maximum tolerated dose to a paradigm driven by target activity. Moving away from the toxicity-driven dose finding and justification model requires an integrated approach in order to adequately characterize the risk-benefit of a drug. This approach starts with understanding the importance of collecting samples for pharmacokinetic and pharmacodynamic assessments in all phases of clinical development to fully characterize the pharmacokinetics and identify covariates and then correlating exposure to key markers of safety and efficacy in pharmacometric analyses to perform a robust risk-benefit assessment and establish the right dose. In addition, for oral agents, decisions on administering the drug with respect to food can impact dose among other clinical trial outcomes such as tolerability and patient compliance. Understanding the importance of model-based drug development as a decision-making tool to support drug development through incorporation of all relevant data allows for a robust risk-benefit assessment at key decision points. Utilization of clinical pharmacology tools and assessments throughout development will provide the key components of a successful oncology development program.

Discovery and Optimization of HKT288, a Cadherin-6-Targeting ADC for the Treatment of Ovarian and Renal Cancers.

Despite an improving therapeutic landscape, significant challenges remain in treating the majority of patients with advanced ovarian or renal cancer. We identified the cell-cell adhesion molecule cadherin-6 (CDH6) as a lineage gene having significant differential expression in ovarian and kidney cancers. HKT288 is an optimized CDH6-targeting DM4-based antibody-drug conjugate (ADC) developed for the treatment of these diseases. Our study provides mechanistic evidence supporting the importance of linker choice for optimal antitumor activity and highlights CDH6 as an antigen for biotherapeutic development. To more robustly predict patient benefit of targeting CDH6, we incorporate a population-based patient-derived xenograft (PDX) clinical trial (PCT) to capture the heterogeneity of response across an unselected cohort of 30 models-a novel preclinical approach in ADC development. HKT288 induces durable tumor regressions of ovarian and renal cancer models in vivo, including 40% of models on the PCT, and features a preclinical safety profile supportive of progression toward clinical evaluation.Significance: We identify CDH6 as a target for biotherapeutics development and demonstrate how an integrated pharmacology strategy that incorporates mechanistic pharmacodynamics and toxicology studies provides a rich dataset for optimizing the therapeutic format. We highlight how a population-based PDX clinical trial and retrospective biomarker analysis can provide correlates of activity and response to guide initial patient selection for first-in-human trials of HKT288. Cancer Discov; 7(9); 1030-45. ©2017 AACR.This article is highlighted in the In This Issue feature, p. 920.

New Insights in Tissue Distribution, Metabolism, and Excretion of [3H]-Labeled Antibody Maytansinoid Conjugates in Female Tumor-Bearing Nude Rats.

For antibody drug conjugates (ADCs), the fate of the cytotoxic payload in vivo needs to be well understood to mitigate toxicity risks and properly design the first in-patient studies. Therefore, a distribution, metabolism, and excretion (DME) study with a radiolabeled rat cross-reactive ADC ([(3)H]DM1-LNL897) targeting the P-cadherin receptor was conducted in female tumor-bearing nude rats. Although multiple components [total radioactivity, conjugated ADC, total ADC, emtansine (DM1) payload, and catabolites] needed to be monitored with different technologies (liquid scintillation counting, liquid chromatography/mass spectrometry, enzyme-linked immunosorbent assay, and size exclusion chromatography), the pharmacokinetic data were nearly superimposable with the various techniques. [(3)H]DM1-LNL897 was cleared with half-lives of 51-62 hours and LNL897-related radioactivity showed a minor extent of tissue distribution. The highest tissue concentrations of [(3)H]DM1-LNL897-related radioactivity were measured in tumor. Complimentary liquid extraction surface analysis coupled to micro-liquid chromatography-tandem mass spectrometry data proved that the lysine (LYS)-4(maleimidylmethyl) cyclohexane-1-carboxylate-DM1 (LYS-MCC-DM1) catabolite was the only detectable component distributed evenly in the tumor and liver tissue. The mass balance was complete with up to 13.8% ± 0.482% of the administered radioactivity remaining in carcass 168 hours postdose. LNL897-derived radioactivity was mainly excreted via feces (84.5% ± 3.12%) and through urine only to a minor extent (4.15% ± 0.462%). In serum, the major part of radioactivity could be attributed to ADC, while small molecule disposition products were the predominant species in excreta. We show that there is a difference in metabolite profiles depending on which derivatization methods for DM1 were applied. Besides previously published results on LYS-MCC-DM1 and MCC-DM1, maysine and a cysteine conjugate of DM1 could be identified in serum and excreta.

Unexpected hepatotoxicity in a phase I study of TAS266, a novel tetravalent agonistic Nanobody® targeting the DR5 receptor.

PURPOSE: TAS266 is a novel agonistic tetravalent Nanobody(®) targeting the DR5 receptor. In preclinical studies, TAS266 was more potent than a cross-linked DR5 antibody or TRAIL. This first-in-human study was designed to evaluate the safety and tolerability, maximum tolerated dose, pharmacokinetics, pharmacodynamics, immunogenicity, and preliminary efficacy of TAS266. METHODS: Adult patients with advanced solid tumors were to receive assigned doses of TAS266 (3, 10, 15, or 20 mg/kg) intravenously on days 1, 8, 15, and 22 of a 28-day treatment cycle. RESULTS: Grade ≥3 elevations in aspartate aminotransferase and/or alanine aminotransferase levels, occurring during cycle 1 in three of four patients at the 3 mg/kg dose level, were attributed to TAS266 and led to early study termination. Liver enzyme levels quickly returned to grade ≤1 following TAS266 discontinuation. Evidence of preexisting antibodies able to bind to TAS266 was found in the three patients who experienced these dose-limiting toxicities. Immunogenic responses remained elevated and strengthened at end-of-treatment (EOT). In the one patient who did not develop hepatotoxicity, no evidence of immunogenicity was observed at baseline or following administration of 4 TAS266 doses; however, incipient positive immunogenicity was observed at the EOT visit. CONCLUSION: TAS266 was associated with unexpected, significant but reversible hepatotoxicity. Although the underlying mechanism is not fully elucidated, factors including the molecule's high potency, immunogenicity to TAS266, and possibly increased DR5 expression on hepatocytes further enhancing the activity of the Nanobody(®) may have contributed to enhanced DR5 clustering and activation of hepatocyte apoptosis.

Multivalent nanobodies targeting death receptor 5 elicit superior tumor cell killing through efficient caspase induction.

Multiple therapeutic agonists of death receptor 5 (DR5) have been developed and are under clinical evaluation. Although these agonists demonstrate significant anti-tumor activity in preclinical models, the clinical efficacy in human cancer patients has been notably disappointing. One possible explanation might be that the current classes of therapeutic molecules are not sufficiently potent to elicit significant response in patients, particularly for dimeric antibody agonists that require secondary cross-linking via Fcγ receptors expressed on immune cells to achieve optimal clustering of DR5. To overcome this limitation, a novel multivalent Nanobody approach was taken with the goal of generating a significantly more potent DR5 agonist. In the present study, we show that trivalent DR5 targeting Nanobodies mimic the activity of natural ligand, and furthermore, increasing the valency of domains to tetramer and pentamer markedly increased potency of cell killing on tumor cells, with pentamers being more potent than tetramers in vitro. Increased potency was attributed to faster kinetics of death-inducing signaling complex assembly and caspase-8 and caspase-3 activation. In vivo, multivalent Nanobody molecules elicited superior anti-tumor activity compared to a conventional DR5 agonist antibody, including the ability to induce tumor regression in an insensitive patient-derived primary pancreatic tumor model. Furthermore, complete responses to Nanobody treatment were obtained in up to 50% of patient-derived primary pancreatic and colon tumor models, suggesting that multivalent DR5 Nanobodies may represent a significant new therapeutic modality for targeting death receptor signaling.

A Phase IB multicentre dose-determination study of BHQ880 in combination with anti-myeloma therapy and zoledronic acid in patients with relapsed or refractory multiple myeloma and prior skeletal-related events.

Dickkopf-1 (DKK1), expressed by myeloma cells, suppresses osteoblast function and plays a key role in bone disease in multiple myeloma. BHQ880, a human neutralizing IgG1 anti-DKK1 monoclonal antibody, is being investigated for its impact on multiple myeloma-related bone disease and as an agent with potential anti-myeloma activity. The primary objectives of this Phase IB study were to determine the maximum tolerated dose (MTD) of BHQ880 and to characterize the dose-limiting toxicity (DLT) of escalating doses in combination with anti-myeloma therapy and zoledronic acid. Twenty-eight patients were enrolled and received BHQ880 at doses of 3-40 mg/kg. No DLTs were reported, therefore, the MTD was not determined. The recommended Phase II dose was declared as 10 mg/kg, based mainly on saturation data. There was a general trend towards increased bone mineral density (BMD) observed over time; specific increases in spine BMD from Cycle 12 onwards irrespective of new skeletal-related events on study were observed, and increases in bone strength at the spine and hip were also demonstrated in some patients. BHQ880 in combination with zoledronic acid and anti-myeloma therapy was well tolerated and demonstrated potential clinical activity in patients with relapsed or refractory multiple myeloma.

Safety, pharmacokinetics, and pharmacodynamics of the DR5 antibody LBY135 alone and in combination with capecitabine in patients with advanced solid tumors.

PURPOSE: We evaluated the safety, maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics, biologic activity, and antitumor efficacy of the DR5 antibody, LBY135 ± capecitabine. EXPERIMENTAL DESIGN: Escalating LBY135 was administered every 21 days, alone (Arm1) or with capecitabine (Arm2), to patients with advanced solid tumors. RESULTS: In Arm1 (n = 40), LBY135 (0.3-40 mg/kg) resulted in no dose-limiting toxicities (DLTs); adverse events (AEs) included fatigue, hypotension, abdominal pain, dyspnea, and nausea. Stable disease (SD) was observed in 21/38 (55.3 %) patients. In Arm2 (n = 33), LBY135 (1-40 mg/kg) plus capecitabine resulted in 3 DLTs (each grade 3): dehydration and mucosal inflammation (1 mg/kg), colitis (20 mg/kg), and diarrhea (40 mg/kg). AEs included fatigue, nausea, dyspnea, and vomiting. Partial response was observed in 2 patients (rectal and breast cancer) and SD in 12/27 (44.4 %) patients. Mean elimination half-life of LBY135 ± capecitabine at saturation of clearance (≥10 mg/kg) ranged between 146 h and 492 h. Immunogenicity was detected in 16/73 (22 %) patients, of which 6 patients experienced reduced LBY135 exposure with repeat dosing. M30/M65 levels were not predictive for LBY135 response. FDG-PET responses were not consistently associated with RECIST responses. CONCLUSIONS: LBY135 was well tolerated up to 40 mg/kg, the maximal dose administered; no MTD for LBY135 ± capecitabine was defined. Clearance was saturated at doses ≥10 mg/kg.

American Association of Pharmaceutical Scientists National Biotechnology Conference Short Course: Translational Challenges in Developing Antibody-Drug Conjugates: May 24, 2012, San Diego, CA.

The American Association of Pharmaceutical Scientists (AAPS) National Biotechnology Conference Short Course "Translational Challenges in Developing Antibody-Drug Conjugates (ADCs)," held May 24, 2012 in San Diego, CA, was organized by members of the Pharmacokinetics, Pharmacodynamics and Drug Metabolism section of AAPS. Representatives from the pharmaceutical industry, regulatory authorities, and academia in the US and Europe attended this short course to discuss the translational challenges in ADC development and the importance of characterizing these molecules early in development to achieve therapeutic utility in patients. Other areas of discussion included selection of target antigens; characterization of absorption, distribution, metabolism, and excretion; assay development and hot topics like regulatory perspectives and the role of pharmacometrics in ADC development. MUC16-targeted ADCs were discussed to illustrate challenges in preclinical development; experiences with trastuzumab emtansine (T-DM1; Genentech) and the recently approved brentuximab vedotin (Adcetris; Seattle Genetics) were presented in depth to demonstrate considerations in clinical development. The views expressed in this report are those of the participants and do not necessarily represent those of their affiliations.

A phase 1 study of lucatumumab, a fully human anti-CD40 antagonist monoclonal antibody administered intravenously to patients with relapsed or refractory multiple myeloma.

In this open-label, multicentre, phase 1 study a fully human anti-CD40 antagonist monoclonal antibody, lucatumumab, was evaluated in patients with relapsed/refractory multiple myeloma (MM). The primary objective was to determine the maximum tolerated dose (MTD) based on dose-limiting toxicities (DLTs). Secondary objectives included safety, pharmacokinetics, pharmacodynamics and antimyeloma activity. Twenty-eight patients, enrolled using a standard '3 + 3' dose escalation, received one or two (n = 3) cycles of lucatumumab 1·0, 3·0, 4·5 or 6·0 mg/kg once weekly for 4 weeks. Common lucatumumab-related adverse events were reversible, mild-to-moderate infusion reactions. Severe adverse events were anaemia, chills, hypercalcaemia and pyrexia (7% each). DLTs included grade 4 thrombocytopenia, grade 3 increased alanine aminotransferase and grade 4 increased lipase (n = 1 each). The MTD was 4·5 mg/kg. At doses ≥3·0 mg/kg, sustained receptor occupancy (≥87%), observed throughout weekly infusions up to 5 weeks after the last infusion, correlated with an estimated half-life of 4-19 d. Twelve patients (43%) had stable disease, and one patient (4%) maintained a partial response for ≥8 months. These findings indicate that single-agent lucatumumab was well tolerated up to 4·5 mg/kg with modest clinical activity in relapsed/refractory MM, warranting further study as a combination therapy.

Phase I study of the anti-CD40 humanized monoclonal antibody lucatumumab (HCD122) in relapsed chronic lymphocytic leukemia.

Lucatumumab is a fully humanized anti-CD40 antibody that blocks interaction of CD40L with CD40 and also mediates antibody-dependent cell-mediated cytotoxicity (ADCC). We evaluated lucatumumab in a phase I clinical trial in chronic lymphocytic leukemia (CLL). Twenty-six patients with relapsed CLL were enrolled on five different dose cohorts administered weekly for 4 weeks. The maximally tolerated dose (MTD) of lucatumumab was 3.0 mg/kg. Four patients at doses of 4.5 mg/kg and 6.0 mg/kg experienced grade 3 or 4 asymptomatic elevated amylase and lipase levels. Of the 26 patients enrolled, 17 patients had stable disease (mean duration of 76 days, range 29-504 days) and one patient had a nodular partial response for 230 days. Saturation of CD40 receptor on CLL cells was uniform at all doses post-treatment but also persisted at trough time points in the 3.0 mg/kg or greater cohorts. At the MTD, the median half-life of lucatumumab was 50 h following the first infusion, and 124 h following the fourth infusion. In summary, lucatumumab had acceptable tolerability, pharmacokinetics that supported chronic dosing and pharmacodynamic target antagonism at doses of 3.0 mg/kg, but demonstrated minimal single-agent activity. Future efforts with lucatumumab in CLL should focus on combination-based therapy.

Inhibition of tumorigenesis driven by different Wnt proteins requires blockade of distinct ligand-binding regions by LRP6 antibodies.

Disregulated Wnt/beta-catenin signaling has been linked to various human diseases, including cancers. Inhibitors of oncogenic Wnt signaling are likely to have a therapeutic effect in cancers. LRP5 and LRP6 are closely related membrane coreceptors for Wnt proteins. Using a phage-display library, we identified anti-LRP6 antibodies that either inhibit or enhance Wnt signaling. Two classes of LRP6 antagonistic antibodies were discovered: one class specifically inhibits Wnt proteins represented by Wnt1, whereas the second class specifically inhibits Wnt proteins represented by Wnt3a. Epitope-mapping experiments indicated that Wnt1 class-specific antibodies bind to the first propeller and Wnt3a class-specific antibodies bind to the third propeller of LRP6, suggesting that Wnt1- and Wnt3a-class proteins interact with distinct LRP6 propeller domains. This conclusion is further supported by the structural functional analysis of LRP5/6 and the finding that the Wnt antagonist Sclerostin interacts with the first propeller of LRP5/6 and preferentially inhibits the Wnt1-class proteins. We also show that Wnt1 or Wnt3a class-specific anti-LRP6 antibodies specifically block growth of MMTV-Wnt1 or MMTV-Wnt3 xenografts in vivo. Therapeutic application of these antibodies could be limited without knowing the type of Wnt proteins expressed in cancers. This is further complicated by our finding that bivalent LRP6 antibodies sensitize cells to the nonblocked class of Wnt proteins. The generation of a biparatopic LRP6 antibody blocks both Wnt1- and Wnt3a-mediated signaling without showing agonistic activity. Our studies provide insights into Wnt-induced LRP5/6 activation and show the potential utility of LRP6 antibodies in Wnt-driven cancer.