Direct Tumor Targeting Research Articles

CTNI-18. RESULTS FROM A PHASE 1 STUDY OF SONODYNAMIC THERAPY WITH WHOLE HEMISPHERIC LOW INTENSITY NON-ABLATIVE ULTRASOUND IN PATIENTS WITH RECURRENT HIGH GRADE GLIOMA

Abstract We report the first use of a novel device that delivers non-ablative low intensity diffuse ultrasound (LIDU) across the entire hemisphere in combination with the oral sonosensitizing agent 5-ALA for the treatment of recurrent high grade glioma. LIDU in combination with 5-ALA focally targets tumor cells with sonodynamic therapy (SDT), causing selective tumor cell death across the entire hemisphere via 1) direct tumor targeting and 2) stimulation of immunogenic cell death. In this 3x3 clinical trial designed for safety (n=12, NCT05362409), two patients were enrolled after multiple recurrences and seven patients had multifocal or multicentric disease. Treatments were delivered monthly for a minimum of four sessions. A treatment duration of 120 minutes was established after dose escalation and expansion. SDT delivered via a novel device and in conjunction with 5-ALA was well tolerated, with no duration-limiting toxicities or serious related adverse events. Compared to historical data, we observed a significant increase in overall survival (mOS of 14.0+ months, with 7 of 12 patients still alive at the time of this submission and final median OS not yet achieved). A Phase 2b randomized, multicenter, double-blind, placebo-controlled study has been planned to commence in 2025 to assess the safety and efficacy of LIDU with sonosensitization in patients with newly diagnosed GBM.

Targeting CD70 using CAR NK cells to enhance NK cells cytolytic effect against osteosarcoma

Abstract Background: Cure rates for osteosarcoma (OS) have not improved in >30 years and no new effectivetherapies have been identified for metastatic disease. Natural killer (NK) cells have become an attractive tool for cancer immunotherapy. Efficay is improved by direct tumor targeting introducing a specific chimeric antigen receptor (CAR). Emerging knowledge suggests CD70 to be a viable candidate as expression is higher in lung metastases and it has been correlated with tumor escape from immune surveillance. Objective: To assess whether using CD70 CAR-NK cells we can enhance trafficking, homing and proliferation of NK cells and therefore therapeutic efficacy against OS. Methods: We analyzed the cBioportal database to verify CD70 expression in OS. Surface expression of CD70 on human OS cell lines and normal osteoblasts was determined by flow cytometry. CD70 CAR constructs were sequenced, verified and transduced into NK cells. CD70 CAR NK and control NK cells cytolytic activity against OS cells was evaluated by IncuCyte. In vitrocytokine release was measured upon CD70 CAR NK/NK cells exposure to OS cells (IsoPlexis). Results: Database analysis confirmed OS CD70 gene amplification. Flow cytometry showed variable expression of CD70 on OS cells and no expression on human osteoblasts. There was an increase in CD70 CAR NK percent lysis against OS cells at the highest effector:target ratios compared to control NK cells. We found a predominant release in the chemoattractive/stimulatory cytokines upon OS cells exposure to CD70 CAR NK cells. Conclusion: CD70 has immunotherapy potential against OS. CD70 CAR NK cells have increased cytolytic activity against OS cells in vitro. Cytolytic activity may be influenced by the release of specific cytokines.

Tumor-targeting engineered probiotic Escherichia coli Nissle 1917 inhibits colorectal tumorigenesis and modulates gut microbiota homeostasis in mice

AimsPreliminary studies have identified the use of probiotics as a potential treatment strategy against colorectal cancer (CRC). However, natural probiotics lack direct tumor-targeting and tumor-killing activity in the intestine. This study aimed to construct a tumor-targeting engineered probiotic to combat CRC. Main methodsStandard adhesion assay was performed to analyze the adherence ability of tumor-binding protein HlpA to CT26 cells. CCK-8 assay, Hoechst 33258 staining and flow cytometry analysis were used for examining cytotoxicity of tumoricidal protein azurin toward CT26 cells. An engineered probiotic Ep-AH harboring azurin and hlpA genes was developed using Escherichia coli Nissle 1917 (EcN) chassis. Antitumor effects of Ep-AH were evaluated in the azoxymethane (AOM) and dextran sodium sulfate salt (DSS)-induced CRC mice. Moreover, analysis of gut microbiota was conducted via fecal 16S rRNA gene sequencing and shotgun metagenomic sequencing. Key findingsAzurin caused a dose-dependent increase of apoptosis in CT26 cells. Ep-AH treatment reversed weight loss (p < 0.001), fecal occult blood (p < 0.01), and shortening of colon length (p < 0.001) than model group, as well as reducing tumorigenesis by 36 % (p < 0.001). Both Ep-H and Ep-A (EcN expressing HlpA or azurin) were less effective than Ep-AH. Furthermore, Ep-AH enriched the members of beneficial bacteria (e.g., Blautia and Bifidobacterium) and reversed abnormal changes of genes associated with several metabolic pathways (e.g., lipopolysaccharide biosynthesis). SignificanceThese results demonstrated that Ep-AH had excellent therapeutic benefits on cancer remission and gut microbiota modulation. Our study provides an effective strategy for anti-CRC treatment.

Abstract 1538: Revisiting the dogma of antibody drug conjugates (ADCs): Emerging data challenge the benefit of linker stability and the primacy of payload delivery

Abstract Antibody drug conjugates (ADCs) are an effective class of cancer therapeutics which have become more prominent after eight FDA approvals in the past three years. ADCs are envisioned to enable the selective delivery of a potent drug to cells that express the antibody target while sparing normal tissues, and thus to improve the therapeutic window by both increasing the maximum tolerated dose (MTD) and decreasing the minimum efficacious dose (MED) of the conjugated drug. Mounting clinical evidence does not support this simplified paradigm [1]. Herein we focus on three prominent issues in ADC development: 1. Alternative mechanisms over and above direct tumor targeting are likely to contribute to ADC therapeutic benefits in the clinic [2]. The responses to certain ADCs in patients with different levels of target antigen expression reveal some target-independent antitumor effects, suggesting the possibility that circulating payload may contribute to efficacy. 2. The preclinical optimization of ADCs is based on efficacy and tolerability in non-human animal studies. Fundamental differences in biology and translatability between species potentially overemphasize the importance of linker stability. 3. Clinical data, although limited, does not support the idea that increased ADC stability drives substantial therapeutic benefit. None of the 13 approved ADCs are completely ‘stable’ in circulation, and more stable drug-linkers have been associated with alternative toxicity profiles and no significant improvement in MTD. Novel meta-analyses and case studies assembled and integrated from &amp;gt;40 approved or clinically active ADCs and &amp;gt;70 discontinued ADCs will be presented in support of these three perspectives. The ADCs included in the analysis differ in terms of payload class, linker type, conjugation chemistry, drug-to-antibody ratio, and antibody target. Gaining a better understanding of the mechanism(s) of action of effective ADCs and the interrelationship between ADC structural components and their pharmacokinetics and pharmacodynamics is critical to inform the next generation of ADCs.

Abstract P063: Novel prodrugs coupled with albumin nanoparticle encapsulation improves antitumor effects of the nucleoside analog gemcitabine

Abstract Nucleoside analogs such as gemcitabine have been widely used to treat many solid tumors. Despite their near universal use and well understood mechanisms of action, this class of chemotherapeutic agents has notable shortcomings including rapid metabolism, limited systemic exposure, acquired resistance, and dose-limiting toxicities. Albumin-based nanoparticles offer several advantages for drug delivery including direct tumor targeting, low risk of immunogenicity, and ease of synthesis and manufacturing. We have modified numerous nucleoside drugs of clinical significance to form new prodrugs and use nanoparticle encapsulation in an attempt to improve the therapeutic index of the parent drugs. Different prodrugs of gemcitabine were designed to evade drug resistance mechanisms, and methods were developed to form stable lyophilized nanoparticle formulations. Nanoparticles were characterized by particle size (~40-65 nm) and polydispersity, and dose-dependent effects on the proliferation of human tumor cell lines were compared to the response to the parent drug gemcitabine. To evaluate effects in vivo, nanoparticle formulations were dosed intravenously (IV) to immunocompromised mice bearing patient-derived xenografts (PDx). The prodrug JTX-836 (IC50=0.46 nM) was ~10x more potent against BxPC-3 pancreatic adenocarcinoma cells than the parent gemcitabine (IC50 = 5.2 nM) in vitro. IV dosing of JTX-836 albumin nanoparticle formulation improved tumor growth inhibition in PDx models of both pancreatic ductal adenocarcinoma (CTG-0282 TumorGraft, Champions Oncology) and ovarian cancer (CTG-1180, Champions Oncology) when compared to IV gemcitabine dosing. These results demonstrate the potential for nanoparticle encapsulation of prodrugs to improve the antitumor activity of existing nucleoside analog therapeutics and support continued development of albumin-based delivery of gemcitabine for the treatment of human cancer. Citation Format: Neil Raheja, Jason Kahana, Robin Jackman, Curtis Monnig. Novel prodrugs coupled with albumin nanoparticle encapsulation improves antitumor effects of the nucleoside analog gemcitabine [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P063.

Updated Results from a Phase Ib Study of Isatuximab Plus Pomalidomide (Pom) and Dexamethasone (dex) in Relapsed/Refractory Multiple Myeloma (RRMM)

Updated Results from a Phase Ib Study of Isatuximab Plus Pomalidomide (Pom) and Dexamethasone (dex) in Relapsed/Refractory Multiple Myeloma (RRMM)

A Phase Ib Study of Isatuximab in Combination with Bortezomib, Cyclophosphamide, and Dexamethasone (VCDI) in Patients with Newly Diagnosed Multiple Myeloma Non-Eligible for Transplantation

Abstract Background: Isatuximab (ISA) is an anti-CD38 monoclonal antibody with multiple modes of action for killing tumor cells through direct tumor targeting and immune cell engagement. It has demonstrated strong potentiation when combined with bortezomib in a multiple myeloma (MM) xenograft model (Deckert J et al, Clin Cancer Res 2014:20:4754). The combination of bortezomib, cyclophosphamide, and dexamethasone (dex) (VCD) is an effective regimen, commonly used in newly diagnosed MM (NDMM) (Leiba M et al, Br J Haematol 2014:166:702). Here, we report initial data from a Phase Ib study of ISA plus VCD (VCDI) in patients (pts) with NDMM (NCT02513186). Methods: This dose-escalation (DE) and expansion study enrolled pts with NDMM ineligible for transplantation. Treatment consisted of 2 phases: induction and maintenance. Induction (one 6-week cycle [cycle (C)1] followed by eleven 4-week cycles [C2-12]): ISA (10 or 20 mg/kg, sequentially enrolled) weekly during C1, then every 2 weeks; subcutaneous bortezomib (1.3 mg/m2) on Days (D)1, 4, 8, 11, 22, 25, 29, and 32 (C1), then weekly (C2-12); cyclophosphamide (300 mg/m2) weekly (C1) then on D1, 8, and 15 (C2-C12); dex (20 mg) on D1, 4, 8, 11, 15, 22, 25, 29, and 32 (C1) then D1, 2, 8, 9, 15, 16, 22, and 23 (aged Results: Enrolment is now complete; 17 pts were treated with VCDI. During the DE phase, 4 pts were treated at 10 mg/kg and 4 pts at 20 mg/kg. Based on initial safety (no DLTs occurred at either dose; MTD was not reached) and pharmacokinetic (PK) data, ISA 10 mg/kg was chosen as the recommended dose for the expansion cohort and 9 additional pts were treated at this dose (total 13 pts at 10 mg/kg). Median age was 71 (68-80) years. At baseline, 1, 1, and 15 pts were ISS Stage I, II, and III, respectively. At data cut-off (Dec 31, 2016), pts across both doses had been treated for a median of 3.0 (0.5-14.0) months (mo). Two pts discontinued treatment due to an adverse event (AE) (10 mg/kg: Grade [Gr] 3 bronchospasm and Gr 3 infusion-associated reaction [IAR]; 20 mg/kg: sudden death [during C1, not treatment related]) and 1 pt (10 mg/kg) discontinued due to disease progression. ISA dose omission was required in 5/13 (38%) pts at 10 mg/kg (Gr 2 bronchitis, Gr 2 mesenteric vein thrombosis, Gr 3 respiratory tract infection, Gr 3 hypertension, Gr 3/4 neutropenia) and none at 20 mg/kg. Dose omission of bortezomib, cyclophosphamide, and dex was required in 7, 5, and 8 pts, respectively. All pts experienced ≥1 AE. Most frequent AEs across both doses (any Gr; excluding laboratory abnormalities): IARs, 8 pts (47%); back pain, 7 pts (41%); nausea, 5 pts (29%); bronchitis, 5 pts (29%); peripheral neuropathy, hypertension, diarrhea, constipation, peripheral edema, and rash, 4 pts each (24%). Gr ≥3 AEs were reported in 11 (65%) pts and serious AEs (SAEs) in 4 (24%) pts (Gr 3 bronchospasm, Gr 2 mesenteric vein thrombosis, Gr 3 dorsal pain, Gr 5 sudden death). Except Gr 3 bronchospasm, no SAEs were treatment related. Nine IARs occurred in 8 pts, all in the first infusion. IARs were Gr 1/2 in all but 1 pt (Gr 3 bronchospasm). Gr 3/4 hematologic abnormalities (laboratory assessment): lymphopenia (8/16 evaluable pts), leukopenia (3/16), neutropenia (3/16), thrombocytopenia (1/16), anemia (1/16). From 15 efficacy-evaluable pts the ORR was 87% (13/15), including 2 stringent CRs, 3 CRs, 4 very good partial responses (VGPRs), and 4 partial responses. Two pts achieved a best response of stable disease, lasting 5 and 12 cycles, respectively. Median time to first response was 1.5 mo. Median duration of response in the DE phase was 11.1 mo, and 14 (82.4%) pts are continuing on treatment. ISA PK appeared unaffected by co-administration with VCD. Conclusions: These data suggest that VCDI is generally well tolerated with many pts demonstrating at least VGPR. Safety and efficacy data (including minimal residual disease status) with longer-term follow-up will be presented at the meeting. Funding: Sanofi Disclosures Ocio: Novartis: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; AbbVie: Consultancy; Pharmamar: Consultancy; Seattle Genetics: Consultancy; Array Pharmaceuticals: Research Funding; Mundipharma: Research Funding; Celgene: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Sanofi: Research Funding; BMS: Honoraria; Janssen: Honoraria. Bringhen: JJ: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria; BMS: Honoraria. Oliva: Celgene: Honoraria; Takeda: Honoraria. Rodriguez-Otero: BMS: Consultancy, Research Funding, Speakers Bureau; Celgene: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau. Kanagavel: Sanofi: Employment. Oprea: Sanofi RD Sanofi: Other: Stock holder. Wei: Sanofi RD Celgene: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Janssen: Honoraria.

Neutrophils as Emerging Immunotherapeutic Targets: Indirect Treatment of Tumors by Regulating the Tumor Immune Environment Based on a Sialic Acid Derivative-Modified Nanocomplex Platform

Tumor cells are dependent on their microenvironment; thus, targeting the non-cancerous components of the tumor might lead to the development of new treatment methods. Neutrophils, which are important inflammatory cells in the tumor microenvironment (TME), significantly affect tumor cell proliferation, metastasis, angiogenesis, and immune regulation. Direct tumor targeting method results in a nanoparticle tumor distribution lower than 0.7%; therefore, targeted regulation of tumor associated neutrophil-related pathways is expected to become a new tumor therapeutic approach. Here, a sialic acid and cholesterol derivative (SA-CH) was synthesized and modified on the surface of nanocomposites to express a novel colchicine derivative (SA-EPG-BCS) for targeted immunotherapy. The interaction between the amphiphilic egg phosphatidylglycerol (EPG) structure and a newly synthesized low-toxic colchicine derivative (BCS) enables a high encapsulation rate, which greatly reduces the BCS toxicity. SA-CH modification improves the ability of the preparation to target peripheral blood neutrophils and exhibits effective anti-tumor activity in vitro and in vivo. Immunohistochemical and pathological section analyses further confirmed that SA-EPG-BCS significantly inhibited neutrophil accumulation in the tumor site, without eliciting unwanted effects. Therefore, the neutrophil migration blocking strategy using an SA-modified colchicine derivative nanocomplex, which treats the tumor indirectly by regulating the tumor immune microenvironment, may become a potential approach for cancer immunotherapy.

Model Based Approach to Evaluate Isatuximab Monthly Dosing Regimen in Relapsed/Refractory Multiple Myeloma Patients

Background: Isatuximab (Isa) is a CD38 monoclonal antibody with multiple modes of action for killing tumor cells through direct tumor targeting and immune cell engagement (Moreno, Clin Cancer Res, 2019). The addition of Isa to pomalidomide (P) and dexamethasone (d) was associated with a significant and clinically meaningful benefit in progression-free survival (PFS) in heavily pre-treated patients with relapsed/refractory multiple myeloma (RRMM) (ICARIA-MM, NCT02514668) (Attal, Lancet, 2019). Isa, in combination with Pd, is approved in the United States, the European Union, Canada, Australia, Switzerland, and Japan for the treatment of adult patients with RRMM who have received at least two prior therapies including lenalidomide and a proteasome inhibitor. Aim: The objectives were to characterize the relationship between serum M-protein kinetics and PFS in RRMM using data from the Phase 3 ICARIA-MM study and to simulate expected longitudinal serum M-protein and PFS when switching to a hypothetical monthly dosing regimen after 6 months. Methods: A joint model of serum M-protein dynamics and PFS was developed using data from 256 evaluable ICARIA-MM patients. Patients received Isa intravenously at 10 mg/kg once weekly (QW) for 4 weeks, then every other week (Q2W) for 28-day cycles in combination with standard Pd (Isa-Pd) or Pd alone in the control arm. A tumor growth inhibition model was used to describe the serum M-protein kinetics under treatment effects of Isa-Pd or Pd alone, in which Isa exposure was predicted using individual PK parameters obtained from the population PK analysis (Fau, Population Approach Group in Europe, 2019) and Pd exposure was predicted from K-PD model using dosing history. Trial simulations were then performed using individual PK/PD parameters of ICARIA-MM patients to evaluate whether efficacy is maintained after switching to a monthly dosing regimen. Results: The joint model identified the instantaneous changes (slope) in serum M-protein as the best on-treatment predictor for PFS and also identified baseline patient characteristics impacting serum M-protein kinetics (serum albumin and serum β2 microglobulin on the baseline serum M-protein levels and the non-IgG type on the serum M-protein growth rate, the serum M-protein slope), and PFS (presence of plasmacytomas). Non-IgG MM patients have similar behavior on serum M-protein kinetics for the first 60 weeks even with higher exposure and similar progression free survival compared to IgG MM patients supporting the non-dose adjustment based on IgG status. Clinical trial simulation of the ICARIA-MM Isa-Pd regimen demonstrated that switching all patients on treatment at 6 months to a monthly Isa regimen would shorten the median time to progression (TTP) (i.e. increase in serum M-protein greater than 25% and an absolute increase greater than 5 g/L compared to nadir) by 4.1 weeks and would shorten median PFS by 2.3 weeks (from 14.03 to 13.45 months). Based on TTP criteria, patients with no risk of earlier progression (57.7%) due to 6 months switch tend to have lower baseline tumor burden (lower serum M-protein and lower percent of bone marrow plasma cell) and better prognostic factors (higher glomerular filtration rate, higher albumin, lower β2 microglobulin). At 6 months, 85% of these patients had predicted stable "at least" VGPR status. Conclusions: Trial simulations supported the choice of the approved isatuximab 10 mg/kg QW/Q2W regimen and showed that switching to a monthly Isa regimen after 6 months may reduce clinical benefit in overall population. However, a subpopulation of patients with good prognosis and obtaining stable at least VGPR status by 6 months may switch to a monthly regimen after 6 months without compromising disease progression risk; this hypothesis will be tested in a prospective clinical trial. Model-based drug development has been successfully applied to support treatment decisions in RRMM patients. Disclosures Thai: Sanofi: Current Employment. Gaudel-Dedieu:Sanofi: Current Employment. Cerou:Sanofi: Current Employment. Sebastien:Sanofi: Current Employment. van de Velde:Sanofi: Current Employment, Current equity holder in publicly-traded company. Semiond:Sanofi: Current Employment. Veyrat-Follet:Sanofi: Current Employment.

Exposure-Response Analyses and Disease Modeling for Selection and Confirmation of Optimal Dosing Regimen of Isatuximab in Combination Treatment in Patients with Multiple Myeloma

Background: Isatuximab (Isa) is an anti-CD38 monoclonal antibody with multiple modes of action for killing tumor cells through direct tumor targeting and immune cell engagement. Exposure-Response (E-R) analysis and disease modelling of tumor burden were performed to evaluate the relationship between Isa exposure and efficacy outcomes. This analysis also supports the Isatuximab dosing regimen selection/confirmation when administered in combination in relapsed/refractory multiple myeloma (RRMM) patients. Methods: To determine the optimal dose for the Phase 3 ICARIA-MM study, E-R analyses were conducted in 44 and 52 RRMM evaluable patients from two Phase 1 trials of Isa in combination with pomalidomide/dexamethasone (Pd) (NCT02283775) or with lenalidomide/dexamethasone (Rd) (NCT01749969), respectively. Isa was administered intravenously at doses from 3 to 20 mg/kg every 2 weeks or weekly for 4 weeks then every 2 weeks (QW/Q2W). In the E-R analyses, several Isa exposure parameters were tested to evaluate if they were predictors of response (partial response [PR] or better). Baseline covariates were also considered in the model to evaluate potential confounding effects. In addition, a second type of analysis was performed on 2 pooled datasets of 153 (single agent and combination with Pd) and 162 (single agent and combination with Rd) evaluable RRMM patients: disease response was also captured by modeling the dynamics of the serum M-protein using a joint model of tumor growth inhibition and drop-out. Trial simulations were then performed to evaluate different dosing regimens of interest. To confirm the dose, E-R analyses were conducted in 297 evaluable RRMM patients from the phase 3 trial (ICARIA-MM; NCT02990338) comparing Isa-Pd (N=148) and Pd (N=149). Isa was administered intravenously at 10 mg/kg QW/Q2W in the Isa-Pd arm. Cox and Weibull (Progression-Free Survival [PFS]) or logistic regression (overall response rate [ORR]) models were used. Results: In the two combination Phase 1 trials, Isa appeared to be well tolerated with no clear dose response relationship between 10 and 20 mg/kg. E-R analyses suggested that higher Isa exposure represented by log Ctrough at 4 weeks (CT4W) was associated with increased ORR. Both models predicted an increased ORR with decreased beta-2 microglobulin and lower number of prior lines of therapy (Rd only), together with higher log CT4W. Clinical trial simulations showed that the probability of success to reach the targeted ORR was high with 10 mg/kg QW/Q2W for both Pd (83% for ORR ≥60%) and Rd (96% for ORR ≥50%). Serum M-protein reduction was greater at doses ≥10 mg/kg compared to doses &lt;10 mg/kg, with minimal differences between 10 and 20 mg/kg QW/Q2W. These analyses supported the rationale for 10 mg/kg QW/Q2W selection for the Phase 3 combination study. In the Phase 3 ICARIA-MM study, the E-R analysis showed that higher CT4W was associated with higher ORR (predicted ORR below and above the median CT4W being 52% and 72%, respectively). The final model also included time since diagnosis and Revised International Staging System (R-ISS) stage at baseline and an interaction between time since diagnosis and R-ISS; ORR increased as time since diagnosis increased and decreased with higher R-ISS stage. For PFS, in addition to CT4W, the model included plasmacytomas, serum albumin level and R-ISS at baseline. The predicted distribution of PFS indicated that patients with greater Isa CT4W had longer PFS, patients with R-ISS Stage III and plasmacytomas had shorter PFS. Matched analyses to Pd indicated that even patients with concentrations ≤median CT4W benefited from Isa treatment (PFS hazard ratio: 0.773). Conclusion: Model-based drug development was successfully applied to support Phase 3 Isa dosing regimen selection for use in combination with Pd in RRMM patients. E-R and clinical data from the Phase 3 ICARIA-MM study confirmed the efficacy and safety of 10 mg/kg QW/Q2W dose/regimen selected. Disclosures Rachedi: Sanofi: Employment. Koiwai:Sanofi: Employment. Gaudel-Dedieu:Sanofi: Employment. Sebastien:Sanofi: Employment. Thai:Sanofi: Employment. El-Cheikh:Sanofi: Employment. Brillac:Sanofi: Employment. Fau:Sanofi: Employment. Nguyen:Sanofi: Employment. Liu:Sanofi: Employment. Campana:Sanofi: Employment. van de Velde:Sanofi: Employment. Semiond:Sanofi: Employment.

PF645 EXPOSURE‐RESPONSE ANALYSIS &amp; DISEASE MODELING FOR SELECTION OF OPTIMAL DOSING REGIMEN OF ISATUXIMAB AS SINGLE AGENT IN PATIENTS WITH MULTIPLE MYELOMA

Background:Isatuximab is an anti‐CD38 monoclonal antibody with multiple modes of action for killing tumor cells through direct tumor targeting and immune cell engagement [1].Aims:Exposure‐Response (E‐R) analysis and disease modelling of tumor burden were performed to evaluate the relationship between isatuximab exposure and efficacy outcome and to support dosing regimen selection for isatuximab as a single agent in relapsed/refractory multiple myeloma (RRMM) patients.Methods:The E‐R analyses were conducted in 194 RRMM patients evaluable for pharmacokinetics (PK) from two monotherapy trials, a phase 1/2 trial (NCT01084252)[2] and a phase 1 trial (NCT02514668). Isatuximab was administered intravenously at doses from 1 to 20 mg/kg once a week or every 2 weeks. Several isatuximab exposure parameters were tested and their association with the probability of achieving an objective response (CR, VGPR or PR) was examined by logistic regression modeling. Baseline covariates were also considered in the model to reduce their potential confounding effects. Disease progression was captured in a subset of 122 evaluable patients with the dynamics of the serum M‐protein and accounted for dropout using a joint model. Trial simulations were then performed to evaluate different dosing regimens of interest using both models.Results:The E‐R relationship was best described by Emax model, in which Ctrough at 4 weeks and percent of bone marrow plasma cells were significant predictors of overall response rate (ORR). Patients with bone marrow plasma cells lower than 50% were more likely to respond. For a given bone marrow plasma cell value, higher probability of response to treatment was obtained with higher Ctrough at 4 weeks. Longitudinal data of M‐protein was adequately described by a tumor growth inhibition model [3,4] and provided more insights into the response of patients over time. Therefore, a high loading dose of 20 mg/kg weekly over 4 weeks was chosen for maximizing the tumor response and a maintenance dose of 20 mg/kg every 2 weeks appeared sufficient to sustain efficacy. Clinical trial simulation demonstrated that this dosing regimen presented a probability of success of 76% to reach 30% ORR (5,000 trials with 100 patients) and would allow 52% reduction of serum M‐protein from baseline at 2 months of treatment. In addition, isatuximab appeared to be well tolerated at this dose level.Summary/Conclusion:Model‐based drug development has been successfully applied to support phase II isatuximab monotherapy dosing regimen selection in RRMM patients. This approach increases both the robustness of dose selection decision making and the chances of success for future clinical trials.

Preliminary Results from a Phase I Study of Isatuximab (ISA) in Combination with Bortezomib, Lenalidomide, Dexamethasone (VRd), and in Patients with Newly Diagnosed Multiple Myeloma (NDMM) Non-Eligible for Transplant

Preliminary Results from a Phase I Study of Isatuximab (ISA) in Combination with Bortezomib, Lenalidomide, Dexamethasone (VRd), and in Patients with Newly Diagnosed Multiple Myeloma (NDMM) Non-Eligible for Transplant

Promising Clinical Efficacy and Toxicity Profile of Isatuximab Based Regimens for Treatment of Newly Diagnosed and Relapsed/Refractory Multiple Myeloma: A Systematic Review

Introduction:Despite the recent advancements in the treatment of multiple myeloma (MM), there is a constant need of newer therapies in order to treat the complex issue of the disease relapse and refractory disease. Isatuximab (ISA) is a non-Food and Drug Administration (FDA) anti-CD38 monoclonal antibody that acts through immune cell engagement and direct tumor targeting. We report efficacy & toxicity of ISA in newly diagnosed MM ((NDMM) as well as relapsed, refractory MM (RRMM) patients (pts).Methods:Following Prisma guidelines, we performed a comprehensive literature search on articles published after January 2012 using PubMed, Embase, Cochrane Library, Web of Science and Clinicaltrials.gov. On initial search, 246 articles were found and after a detailed screening, 6 completed and 11 ongoing phase I/II/III studies were included.Results:A total of 249 pts were included. Two hundred thirty-four pts had RRMM while 15 pts had NDMM, overall response rate (ORR) was 37.60% and 87% respectively. In a phase I trial involving 34 pts with RRMM, single-agent ISA (1-20 mg/kg) was given. The median age of pts was 64 years (y) [range (r) = 38-85]. The overall response rate (ORR) was 24% with a partial response (PR) in 18% pts. The most common adverse events (AEs) were nausea (34%), fatigue (49%), fever (29%) and headache (26%) and upper respiratory infection (23%). In a phase II trial, 97 pts with RRMM were stratified into 4 groups. Single-agent ISA [3mg/kg, every 2 week,(Q2W); 10 mg/kg, Q2W - every 4 weeks (Q4W); 10 mg/kg (Q2W), 20 mg/kg (QW-Q2W)] was given. The median age of pts was 62.5 y (r = 38-85). The ORR was 9%, 20%, 29% and 24% respectively. The cumulative ORR was 20.6%. The median time to first response was 1.4 months (M) while the median duration of response was 6.6 M. The most common AEs were nausea (33%), fatigue (30%), diarrhea (26%) and cough (24%). In a phase Ib trial, 57 pts with RRMM were stratified into 5 groups. ISA [3 mg/kg (Q2W); 5 mg/kg (Q2W); 10 mg/kg (Q2W); 10 mg/kg (QW-Q2W); 20 mg/kg (QW-Q2W)] in combination with lenalidomide (R) (25mg), and dexamethasone (D) (40 mg) was given. The median age of pts was 61 y (r = 42-76). The median time since the initial diagnosis was 4 y. The ORR was 33%, 67%, 63%, 50%, and 50% respectively. The cumulative ORR was 56% with complete response (CR) in 3.8 % pts, very good partial response (VGPR) in 32.7 % pts and PR in 19.2 % pts. The progression-free survival (PFS) was 8.5 M (r=4.73-16.59). The most common grade 3 and 4 AEs were neutropenia (60%), lymphopenia (58%), leukopenia (53%), anemia (25%), thrombocytopenia (38%), pneumonia (9%), fatigue (7%), and dyspnea (4%). In another phase Ib trial, 36 pts with RRMM were stratified into 3 groups. ISA (5 mg/kg; 10 mg/kg, 20 mg/kg) in combination with pomalidomide (P) (4 mg), and D (40 mg) was given. The ORR was 63%, 55%, and 50% respectively. The cumulative ORR was 55.5%. The median time to first response was 4.1 weeks (W) while the median duration of response was 33.1 W. The most common grade 3 AEs were neutropenia (81%), lymphopenia (75%), and leukopenia (75%). In another phase Ib trial involving 10 pts with RRMM, ISA (10-20 mg/kg) in combination with carfilzomib (CFZ) (27 mg) was given. The median number of prior lines of therapy was 4.5 (2-8). The ORR was 80% with VGPR in 20% pts and PR in 60% pts. The most common grade 3 and 4 AEs were lymphopenia (64%), anemia (9%), and neutropenia (9%). In a phase Ib trial involving 15 pts with NDMM, ISA (10 mg) in combination with bortezomib (V) (1.3 mg/m2) and cyclophosphamide (CY) (300 mg/m2) was given. The median age of pts was 71 y (r= 68-80). The ORR was 87% with CR in 33% pts, VGPR in 27% pts, and PR in 27% pts. The median time to first response was 1.5 M while the median duration of response was 11 M. The most common grade 3 and 4 AEs were lymphopenia (50%), leucopenia (18%), neutropenia (8%), anemia (6%) and thrombocytopenia (6%).Conclusion:In RRMM pts, ISA as a single agent has shown weaker efficacy when compared to combination regimens i.e. ORR 21% vs. 58%. The best result was seen when ISA was used in combination with CFZ demonstrating an ORR of 80%. In NDMM pts, combination regimens have shown excellent efficacy with an ORR of 87%. Nausea and fatigue were the major AEs reported with the monotherapy while neutropenia, leucopenia, and lymphopenia were the major AEs reported with the combination regimens. Further studies involving a larger population are required to gather evidence in favor of the improved efficacy and to evaluate AEs. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Development of Bispecific Antibody Derivatives for Cancer Immunotherapy.

Development of antibody-based immunotherapeutics has progressed from direct tumor-targeting, with antibodies such as rituximab, to blocking of immune checkpoints to reactivate antitumor immunity. In addition, bispecific antibodies/antibody fragments are also of great interest in cancer therapy, as these constructs have the ability to redirect immune effector cells to cancer targets and, thereby, enhance therapeutic efficacy. A number of bispecific antibody formats have been reported, with the first FDA-approved bispecific antibody being blinatumomab, a so-called bispecific T cell engager (BiTE), which redirects and potently activates T cell immune responses. Recently, we described an additional novel bispecific antibody derivative, termed RTX-CD47, which was designed to inhibit the innate immune checkpoint CD47-SIRPα only on -positive cancer cells. RTX-CD47 contains two antibody fragments in tandem and has monovalent binding specificity for CD47 and . Only upon dual binding to and CD47 RTX-CD47 blocks CD47 "Don't eat me" signaling. Here, we provide a detailed protocol for the construction and functional evaluation of such a bispecific antibody derivative.

Phase I dose-escalation study of 225Ac-J591 for progressive metastatic castration resistant prostate cancer (mCRPC).

TPS399 Background: PC is a radiosensitive disease. PSMA is overexpressed in advanced PC with upregulation by androgen receptor (AR) pathway dysregulation; limited expression exists in other organs. A series of sequential studies of beta-emitting radiolabeled anti-PSMA monoclonal antibody (mAb) J591 have demonstrated accurate targeting, efficacy with dose-response effect, and safety with predictable, reversible dose-limiting myelosuppression. Alpha emitters are significantly more potent with a shorter range than beta emitters. Though there is no direct tumor-targeting, the bone-targeting alpha emitter Ra223 is approved. Anecdotal reports of PSMA small molecule targeted alpha emitters have hinted at efficacy but are limited by xerostomia and in mouse models may lead to long-term renal damage. Intact mAb J591 has comparatively no to minimal distribution in salivary glands and kidneys. Preclinical studies demonstrated purity, immunoreactivity, and stability with efficacy in a xenograft model [AACR 2017]. Methods: Men with progressive mCRPC following at least 1 potent AR-targeted agent (e.g. abi/enza) and docetaxel (or unfit/refuse chemo) without limit of # prior therapies (excluding beta-emitting bone-targeted radioisotopes) provided adequate organ function will undergo imaging with 68Ga-PSMA-11 PET/CT followed by a single dose of 225Ac-J591. Single-subject cohorts will be enrolled until grade &gt; 1 attributable toxicity, then transition to 3+3 design. Cohort 1 = 13.3 KBq/kg with planned escalation up to 93.3 KBq/kg of 225Ac with fixed 20 mg J591. Dose-limiting toxicity (DLT) is defined as attributable grade 4 heme toxicity or grade 3/4 non-heme toxicity. Planned cohort expansion will occur at recommended phase 2 dose (RP2D) in a 2-stage design. The primary endpoint is determination of DLT and RP2D. Secondary endpoints include toxicity, PSA decline rate, RECIST response, PFS, rPFS, OS, and patient reported outcomes (FACT-P and BPI-SF). Correlatives include baseline/follow up PSMA imaging, CTC count (CellSearch) changes, tissue and circulating genomic assessment, and immune studies. Enrollment began in October, 2017. Clinical trial information: NCT03276572.

Abstract 2136: Inhibiting cancer growth by targeting the TNFR2 oncogene with TNFR2 antagonistic antibodies

Abstract Background: Although antibody targeting of the HER2 oncogene represents an outstanding clinical treatment and a success story showing direct cancer killing with antibodies, many oncogenes are intracellular and are not expressed broadly, whether on a single or multiple tumor types. The recently discovered TNFR2 oncogene is broadly expressed on many human tumors. Colon cancer cells, multiple myeloma cells, renal cell carcinoma cells, Hodgkin’s lymphoma cells, ovarian cancer epithelial cells and cutaneous non-Hodgkin’s lymphoma cells can aberrantly express the TNFR2 receptor as an oncogene for growth. For non-cutaneous T cell lymphomas, the genetic basis of the TNFR2 deregulation has recently been tied to constitutive overexpression of TNFR2 from frequent gene duplications or cytoplasmic TNFR2 mutations that confer constitutive agonism, i.e. tumor expansion. These features make TNFR2 an advantageous molecular target for direct tumor targeting. Methods: We designed monoclonal antibodies to target the TNFR2 oncogene and directly kill human tumor cells. TNFR2-directed antibodies were screened for their ability to induce the death of rapidly growing tumor cells, such as ovarian cancer cells (i.e., OVCAR3). Results: Novel dominant anti-TNFR2 antibody candidates (TNFR2 antagonistic antibodies) did not require Fc binding for activity, expressed dominance over TNF-mediated agonism, and hampered intracellular NF-κB activation and phosphorylation obligatory for TNFR2 signaling and cell growth of tumor cells. Even low doses of TNFR2 antagonists rapidly and directly killed TNFR2 oncogene-expressing ovarian cancer cells. Examination of the structural biology of these dominant TNFR2 antagonist antibodies uncovered a unique and stabilizing TNFR2 receptor formation, anti-parallel dimeric TNFR2, which inhibits intracellular signaling, cannot bind TNF, cannot be cleaved to create soluble TNFR2 and is exponentially more active on the dividing cells of cancer. Conclusions: TNFR2 is a unique and broadly expressed human oncogene that can potentially be targeted to directly stop the growth of cancer cells (including ovarian cancer cells) by antibody-induced cell death. The creation of dominant TNFR2 antagonism provides a unique, non-signaling complex that has implications for the therapeutic targeting of TNF superfamily receptors, especially TNFR2. Citation Format: Heather Torrey, John Butterworth, Toshiyuki Mera, Yoshiaki Okubo, Limei Wang, Danielle Baum, Audrey Defusco, Sara Plager, Sarah Warden, Daniel Huang, Eva Vanamee, Rosemary Foster, Denise L. Faustman. Inhibiting cancer growth by targeting the TNFR2 oncogene with TNFR2 antagonistic antibodies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2136. doi:10.1158/1538-7445.AM2017-2136

Preliminary Results From a Phase Ib Study of Isatuximab in Combination with Pomalidomide (Pom) and Dexamethasone (Dex) in Relapsed and Refractory Multiple Myeloma (RRMM)

Preliminary Results From a Phase Ib Study of Isatuximab in Combination with Pomalidomide (Pom) and Dexamethasone (Dex) in Relapsed and Refractory Multiple Myeloma (RRMM)

Preliminary Results from a Phase Ib Study of Isatuximab in Combination with Pomalidomide and Dexamethasone in Relapsed and Refractory Multiple Myeloma

Preliminary Results from a Phase Ib Study of Isatuximab in Combination with Pomalidomide and Dexamethasone in Relapsed and Refractory Multiple Myeloma

Updated data from a phase II dose finding trial of single agent isatuximab (SAR650984, anti-CD38 mAb) in relapsed/refractory multiple myeloma (RRMM).

8005Background: Isatuximab (ISA) is a humanized anti-CD38 monoclonal antibody with multiple modes of action for killing tumor cells through direct tumor targeting and immune cell engagement. Here, ...

AAVP displaying octreotide for ligand-directed therapeutic transgene delivery in neuroendocrine tumors of the pancreas

Patients with inoperable or unresectable pancreatic neuroendocrine tumors (NETs) have limited treatment options. These rare human tumors often express somatostatin receptors (SSTRs) and thus are clinically responsive to certain relatively stable somatostatin analogs, such as octreotide. Unfortunately, however, this tumor response is generally short-lived. Here we designed a hybrid adeno-associated virus and phage (AAVP) vector displaying biologically active octreotide on the viral surface for ligand-directed delivery, cell internalization, and transduction of an apoptosis-promoting tumor necrosis factor (TNF) transgene specifically to NETs. These functional attributes of AAVP-TNF particles displaying the octreotide peptide motif (termed Oct-AAVP-TNF) were confirmed in vitro, in SSTR type 2-expressing NET cells, and in vivo using cohorts of pancreatic NET-bearing Men1 tumor-suppressor gene KO mice, a transgenic model of functioning (i.e., insulin-secreting) tumors that genetically and clinically recapitulates the human disease. Finally, preclinical imaging and therapeutic experiments with pancreatic NET-bearing mice demonstrated that Oct-AAVP-TNF lowered tumor metabolism and insulin secretion, reduced tumor size, and improved mouse survival. Taken together, these proof-of-concept results establish Oct-AAVP-TNF as a strong therapeutic candidate for patients with NETs of the pancreas. More broadly, the demonstration that a known, short, biologically active motif can direct tumor targeting and receptor-mediated internalization of AAVP particles may streamline the potential utility of myriad other short peptide motifs and provide a blueprint for therapeutic applications in a variety of cancers and perhaps many nonmalignant diseases as well.