Reversible Thrombocytopenia Research Articles

Reversible Thrombocytopenia of Functional Platelets after Nose-Horned Viper Envenomation Is Induced by a Snaclec.

Profound and transient thrombocytopenia of functional platelets without bleeding was observed in patients envenomed by Vipera a. ammodytes (Vaa). This condition was rapidly reversed by administration of F(ab)2 fragments of immunoglobulin G targeting the whole venom, leaving platelets fully functional. To investigate the potential role of snake venom C-type lectin-like proteins (snaclecs) in this process, Vaa-snaclecs were isolated from the crude venom using different liquid chromatographies. The purity of the isolated proteins was confirmed by Edman sequencing and mass spectrometry. The antithrombotic effect was investigated by platelet agglutination and aggregation assays and blood coagulation tests. Using flow cytometry, the platelet activation and binding of Vaa-snaclecs to various platelet receptors was analyzed. Antithrombotic efficacy was tested in vivo using a mouse model of vascular injury. Two Vaa-snaclecs were purified from the venom. One of them, Vaa-snaclec-3/2, inhibited ristocetin-induced platelet agglutination. It is a covalent heterodimer of Vaa-snaclec-3 (α-subunit) and Vaa-snaclec-2 (β-subunit). Our results suggest that Vaa-snaclec-3/2 induces platelet agglutination and consequently thrombocytopenia by binding to the platelet receptor glycoprotein Ib. Essentially, no platelet activation was observed in this process. In vivo, Vaa-snaclec-3/2 was able to protect the mouse from ferric chloride-induced carotid artery thrombosis, revealing its applicative potential in interventional angiology and cardiology.

Reversible thrombocytopenia of functional platelets after the nose-horned viper venom envenomation is induced by a snaclec

Reversible thrombocytopenia of functional platelets after the nose-horned viper venom envenomation is induced by a snaclec

Navitoclax safety, tolerability, and effect on biomarkers of senescence and neurodegeneration in aged nonhuman primates

Alzheimer's disease (AD) is the most common global dementia and is universally fatal. Most late-stage AD disease-modifying therapies are intravenous and target amyloid beta (Aβ), with only modest effects on disease progression: there remains a high unmet need for convenient, safe, and effective therapeutics. Senescent cells (SC) and the senescence-associated secretory phenotype (SASP) drive AD pathology and increase with AD severity. Preclinical senolytic studies have shown improvements in neuroinflammation, tau, Aβ, and CNS damage; most were conducted in transgenic rodent models with uncertain human translational relevance. In this study, aged cynomolgus monkeys had significant elevation of biomarkers of senescence, SASP, and neurological damage. Intermittent treatment with the senolytic navitoclax induced modest reversible thrombocytopenia; no serious drug-related toxicity was noted. Navitoclax reduced several senescence and SASP biomarkers, with CSF concentrations sufficient for senolysis. Finally, navitoclax reduced TSPO-PET frontal cortex binding and showed trends of improvement in CSF biomarkers of neuroinflammation, neuronal damage, and synaptic dysfunction. Overall, navitoclax administration was safe and well tolerated in aged monkeys, inducing trends of biomarker changes relevant to human neurodegenerative disease.

Examination of in vitro and in vivo antitumor activity of PARP1 selective inhibitor D0112-005.

e15115 Background: The approved PARP inhibitors have demonstrated efficacy in ovarian, breast, prostate, and pancreatic cancers, particularly in homologous recombination repair (HRR)-deficient tumors, including BRCA mutant tumors. The severe hematological toxicity of first-generation PARPi in combination with chemotherapy is due to the lack of selectivity for PARP2. So, we developed selective PARP1 inhibitor D0112-005 with the aim to improve safety and efficacy. Methods: The selectivity of D0112-005 on PARP1, PARP2 was measured by chemiluminescent assay kit and PARP trap™ assay kit. The anti-proliferative ability of D0112-005 was evaluated by CCK-8 in BRCA mutant cell lines. In vivo anti-tumor effect of D0112-005 was evaluated in MDA-MB-436 BRCA1 mutant xenograft model. The potential for hematologic toxicity was evaluated in rats for 28 days repeat-dose and dogs for 14 days repeat-dose. Results: D0112-005 is a highly potent and selective inhibitor of PARP1 with 2000-fold selectivity for PARP1 over PARP2 and PARP3. D0112-005 trapped PARP1-DNA with an EC50 value of 6.49 nM. In contrast, the EC50 of PARP2-DNA trapping was 430μM. These data demonstrate that D0112-005 is a potent and selective PARP1 trapper. D0112-005 showed high anti-proliferation activity against BRCA mutant MDA-MB-436 and HCC1395 cell lines, with IC50 values of 2.06 nM and 2.446 nM, respectively. In the MDA-MB-436 BRCA1m xenograft model, a dose-dependent anti-tumor effect was observed after 21 days administration, with TGIs of 38.77%, 106.7% and 111.73% at the dose of 0.1, 0.3 or 1 mg/kg once daily by oral, respectively. In the 1 mg/kg group, the anti-tumor efficacy was maintained after 14 days of drug withdrawal. D0112-005 showed well tolerance without bodyweight loss. In rat 28 days repeat dose study, D0112-005 100mg/kg had less changes on hematologic parameters compared with Olaparib. The main toxic reaction of D0112-005 (10mg/kg) was reversible thrombocytopenia in dog 14 days repeated toxicity study. Conclusions: D0112-005 potently and selectively inhibits PARP1 resulting in excellent anti-tumor activity in vivo and in vitro, which also good safety profile in the repeated toxicity study in rats and dogs.

Preclinical and Early Clinical Results Indicate a Role for the Oral p300/CBP Inhibitor Inobrodib (CCS1477) in T-Cell Lymphoma

Inobrodib (CCS1477) is a potent, selective, and orally bioavailable inhibitor of the bromodomains of CBP and EP300, two homologous histone acetyltransferases with critical roles in cellular growth and differentiation. Lymphomas can harbor multiple putative predictive biomarkers for inobrodib, including deleterious mutations in CBP/EP300 that convey synthetic lethality and expression of the lineage transcription factors IRF4 and GATA3. The preclinical efficacy of inobrodib was assessed in a range of solid cancer and hematological cancer cell lines. Select models, including multiple myeloma, acute myeloid leukaemia, and lymphoma cell lines were sensitive to submicromolar concentrations of inobrodib. These in vitro results were extended to xenograft models in which inobrodib demonstrated dose-dependent efficacy. Based on these results, we initiated a clinical trial to test the safety and efficacy of inobrodib in advanced hematological malignancies (NCT04068597). Dose escalation was conducted in multiple myeloma patients and select B and T-cell lymphomas. The safety profile was similar to other hematological and solid tumour indications with readily manageable and reversible thrombocytopenia as the main toxicity. The recommended phase 2 dose was established at 35mg bidaily on a 4 days on/3 days off intermittent schedule. Initial data in peripheral T cell lymphoma - not otherwise specified (PTCL-NOS) shows a potential benefit with objective responses in 3 of 4 patients as of data cut-off date (20 Jul 2023). These included a complete metabolic response in a patient (with previously refractory disease) continuing on treatment for over 1.5 yrs and 2 patients with minor responses. Translational investigations indicate that responders all express IRF4 and GATA3, but do not harbour CBP/EP300 mutations. Together these data support the further development of inobrodib for the treatment of peripheral T cell lymphoma. Expansion continues with a focus on T-cell lymphomas, which may be driven by IRF4 and GATA3.

Selinexor in Combination with R-GDP for Patients with Relapsed/Refractory B-Cell Lymphoma: Final Results of 18 Patients Treated at RP2D of Selinexor in the Selinda Phase Ib Lysa Study

Background: Salvage chemotherapy followed by high-dose therapy (HDT) and autologous stem-cell transplantation (ASCT) is an option to treat young patients (pts) with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL). A complete remission before ASCT is the most important prognosis factor for a better outcome. Selinexor is a first-in-class, oral selective inhibitor of nuclear export which, through XPO1 blockade, causes nuclear accumulation and activation of tumor suppressor proteins, reduction in oncoproteins and cancer cell apoptosis. Selinexor has been approved by the US Food and Drug Administration for the treatment of R/R DLBCL, including de novo or transformed from follicular lymphoma (FL) pts after ≥2 therapies. The phase Ib SELINDA (EUDRACT 2015-005612-15) study assessed safety and efficacy of selinexor, in combination with R-GDP for pts with R/R B-cell lymphoma. Patients & methods: Eligible pts <70 years with R/R B-cell lymphoma after first or second treatment failure received every 21 days (d) 3 cycles of rituximab 375 mg/m² on D1, dexamethasone 40 mg on D1 to 4, cisplatin 75 mg/m² D1 and gemcitabine 1000 mg/m² on D1 and 8 (R-GDP) in combination with escalating doses of selinexor. Two dose levels of selinexor, 40mg and 60mg, were evaluated via 3+3 design. Initial dosing of selinexor for dose level 1 (DL1) was 40 mg on D1, 3, 8, 10. The dosing was modified to 40mg and 60mg on D1, 8, 15 for DL1 and DL2, respectively. The primary endpoint of SELINDA was the determination of the recommended phase 2 dose (RP2D) of selinexor in combination with R-GDP. Secondary and exploratory endpoints were safety, efficacy, and feasibility of ASCT after selinexor-R-GDP. Results: The R2PD for selinexor in combination with R-GDP was established as 40mg on days 1, 8, and 15 (Maerevoet, IMCL 2021#176). Between January 2017 and January 2021, 32 pts received selinexor-R-GDP. We focused on the 18 pts who received the R2PD: 15 had DLBCL, 2 FL, 1 marginal zone lymphoma. In this cohort, median age was 61 years (range 44-69); 14 pts (78%) had stage III/IV, 6 had disease refractory to last treatment, 12 had relapsed. Thirteen pts received 1 previous line of treatment before inclusion, 5 pts received 2 previous lines. Four pts prematurely discontinued treatment: 2 for thrombocytopenia, 1 for COVID, 1 for disease progression. Major adverse events (AEs) in >10% of pts were reversible neutropenia (55 %), thrombocytopenia (44 %), and nausea (22%). No fatal AEs were observed. One patient is not evaluated, 7 pts (39%) achieved a complete metabolic response (CMR), 5 pts (28%) partial metabolic response (PMR) and 5 pts (28%) stable disease or progressive disease. According to Lugano criteria's, overall response rate (ORR) assessed at the end of treatment was 67%. Nine of the 15 pts (60 %) with DLBCL had metabolic response (CMR: 4, PMR: 5). Per protocol, peripheral stem cell collection and ASCT were optional, 4 pts of this RP2D cohort proceeded to high dose therapy with BEAM conditioning and ASCT. For this RP2D cohort, the 1-year overall survival is 72.2% and the 1 Year-PFS is 45%. The median duration of response was not reached (95%CI: 0.4-NA) (figure 1) Conclusion: This study established the safety profile of weekly 40mg of selinexor in combination with R-GDP for R/R B cell lymphoma with an ORR of 67%, the median DOR is not reached. Reversible AEs were as expected for a platinum combination regimen. An ongoing randomized phase 2 study comparing R-GDP with or without selinexor in pts with R/R DLBCL will further evaluate the safety and efficacy of the combination. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The efficacy, toxicity and survival of salvage retreatment PRRT with 177Lu-DOTATATE in patients with progressive NET following initial course of PRRT.

To evaluate the efficacy, toxicity and survival of salvage peptide receptor radionuclide therapy (PRRT) with indigenous, direct-route 177Lu-labelled-DOTATATE in metastatic Nueroendocrine tumor (NET) patients who showed an objective response or disease stabilization following initial course of 177Lu-DOTATATE PRRT cycles and eventually developed progressive disease after a time-interval of more than 1 year; the variables influencing survival and response of salvage PRRT were also examined. A total of 26 progressive metastatic NET patients who received salvage PRRT with indigenous 177Lu-DOTATATE, were evaluated. Response was assessed under three broad categories as clinical symptomatic, biochemical and imaging (both molecular and morphological imaging). The Kaplan-Meier product-limit method was used to calculate progression-free survival (PFS) and overall survival (OS). Toxicity of salvage PRRT was evaluated by NCI-CTCAE v. 5.0 criteria (included complete blood counts, renal and liver function tests). Association between various variables and response and survival were analyzed using the χ2 test. Out of the 26 patients, the complete follow-up data were not available for four patients, where only survival information was available. Thus, a total of 22 patients (median age: 55 years, range: 38-68 years, 12 men and 10 women) were included and analyzed retrospectively in study. The cumulative dose of initial course of PRRT (I-PRRT) with indigenous 177Lu-DOTATATE ranged from 800 mCi (29.6 GBq) to 1231 mCi (45.54 GBq) per patient {mean administered cumulative dose of 964 mCi (35.66 GBq) per patient}, and the salvage PRRT with indigenous 177Lu-DOTATATE comprised of a mean dose of 170 mCi (6.29GBq) per patient. The disease control rate of 68.1%, 77.3%, 63.6% and 63.6% were observed after salvage PRRT on clinical symptomatic, biochemical, molecular and morphological imaging response respectively. The median PFS after salvage PRRT was 17 months. The median OS was not attained after I-PRRT (OS-i) and salvage PRRT (OS-s). Estimated OS-i rate was 68% at 108 months and OS-s rate was 82% at 18 months. None of the patients developed Grade 3/4 hematotoxicity, nephrotoxicity and hepatotoxicity or AML/MDS after I-PRRT and salvage PRRT at median follow-up of 72 months and 12 months respectively. The highest level of toxicity was Grade 2 [seen as reversible anemia, thrombocytopenia and nephrotoxicity in 3 (13.5%), 1 (4.5%) and 2 patients (9%) respectively]. The significant p-value was not observed for any variable association. With limited therapeutic options available for progressive NET after I-PRRT and in the absence of high-grade toxicity after 177Lu-DOTATATE salvage PRRT, retreatment with PRRT may be considered as a relatively safe therapeutic option for these patients. This study examined salvage retreatment PRRT with indigenous "direct-route" 177Lu-DOTATATE and registered its safety and survival benefits, indicating this could be an effective therapeutic option in this clinical setting.

Abstract CT513: Phase I study of IBI322 (anti-CD47/PD-L1 bispecific antibody) monotherapy therapy in patients with advanced solid tumors in China

Abstract Background: IBI322 is an anti-CD47/PD-L1 bispecific antibody that blocks both the PD-1/PD-L1 and CD47/SIRP-α pathways. By an “imbalanced” design with a lower binding affinity to CD47 and a higher binding affinity to PD-L1, preclinical models showed IBI322 blocks CD47 on CD47+/PD-L1+ tumors more selectively than a regular CD47 monoclonal antibody does, with minimal impact on RBCs. We conducted first-in-human, phase I study of IBI322 monotherapy in patients with advanced solid tumors. Here, we report the results from early dose escalation/expansion part of the study. Methods: Eligible patients (18-75 years of age, ECOG PS 0-1) had locally advanced, recurrent, or metastatic solid tumors without available therapies to confer clinical benefit. The dose escalation (0.01 to 45 mg/kg, QW/Q2W/Q3W, IV) followed an accelerated titration and a standard 3+3 design. Dose expansion part was conducted at 10-30mg/kg Q2-3W groups. The primary objectives of this study were to evaluate the safety, tolerability and preliminary anti-tumor activity (per RECIST v1.1) of IBI322. Results: As the data cut-off date on October 12, 2021, 58 patients were enrolled (age: 53±11.7 years, 37 [63.8%] males, ECOG PS 1: n=38 [65.5%], previously ICI treated: n=15 [25.9%]). Only one DLT of grade 4 reversible thrombocytopenia was observed at 20mg/kg Q2W group. Treatment-related adverse events (TRAEs) of any grade occurred in 43 (74.1%) patients. The most frequent TRAEs including anemia (31.0%), thrombocytopenia (22.4%), and pyrexia (15.5%). Grade ≥3 TRAEs occurred in 13 (22.4%) patients, the most frequent Grade ≥3 TRAE was thrombocytopenia (12.1%). All thrombocytopenia was asymptomatic, transient, and reversible within 10 days. No thrombocytopenia led to any hemorrhage. Investigator-determined immune-related adverse events occurred in 10 (17.2%) patients. Two (3.4%) patients experienced infusion reaction. Among 20 patients treated at active doses (≥10 mg/kg) and with at least one tumor assessment, 4 (20%) achieved PR, and 7 (35%) achieved SD. Among 9 patients with NSCLC (including 4 patients failed on prior ICI treatment) who were treated at active doses (≥10 mg/kg), 3 (33.3%) achieved PR, and 5 (55.6%) achieved SD. As of data cut-off date, all these 4 patients achieved PR mentioned above still remained on IBI322 monotherapy. Conclusion: IBI322 monotherapy showed a manageable safety profile with a promising anti-tumor activity in heavily treated patients with advanced malignancies. Study is ongoing to further evaluate IBI322 monotherapy and in combination with other regimen in various types of solid tumor. Clinical trial information: NCT04328831, NCT04912466 Citation Format: Jie Wang, Yuping Sun, Qian Chu, Jianchun Duan, Rui Wan, Zhijie Wang, Jun Zhao, Haoyuan Li, Yingmei Guo, Yuling Chen, Yan Wang. Phase I study of IBI322 (anti-CD47/PD-L1 bispecific antibody) monotherapy therapy in patients with advanced solid tumors in China [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT513.

Selinexor in Combination with R-GDP for Patients with Relapsed/Refractory B-Cell Lymphoma: Results of the Selinda Phase Ib Lysa Study

Selinexor in Combination with R-GDP for Patients with Relapsed/Refractory B-Cell Lymphoma: Results of the Selinda Phase Ib Lysa Study

Phase 1 study of ibrutinib and the CXCR4 antagonist ulocuplumab in CXCR4-mutated Waldenström macroglobulinemia

AbstractMYD88 and CXCR4 mutations are common in Waldenström macroglobulinemia (WM). Mutated CXCR4 (CXCR4Mut) impacts BTK-inhibitor response. We conducted a phase 1 trial of the CXCR4-antagonist ulocuplumab with ibrutinib in this first-ever study to target CXCR4Mut in WM. Ibrutinib was initiated at 420 mg/d with cycle 1 and continued until intolerance or progression; ulocuplumab was given cycles 1 to 6, with a 3 + 3 dose-escalation design. Each cycle was 4 weeks. Thirteen symptomatic patients, of whom 9 were treatment-naive patients were enrolled. Twelve were evaluable for response. At best response, their median serum immunoglobulin M declined from 5574 to 1114 mg/dL; bone marrow disease decreased from 65% to 10%, and hemoglobin increased from 10.1 to 14.2 g/dL (P < .001). The major and VGPR response rates were 100% and 33%, respectively, with VGPRs observed at lower ulocuplumab dose cohorts. Median times to minor and major responses were 0.9 and 1.2 months, respectively. With a median follow-up of 22.4 months, the estimated 2-year progression-free survival was 90%. The most frequent recurring grade ≥2 adverse events included reversible thrombocytopenia, rash, and skin infections. Ulocuplumab dose-escalation did not impact adverse events. The study demonstrates the feasibility of combining a CXCR4-antagonist with ibrutinib and provides support for the development of CXCR4-antagonists for CXCR4Mut WM. This trial was registered at www.clinicaltrials.gov as #NCT03225716.

Reversible thrombocytopenia during hibernation originates from storage and release of platelets in liver sinusoids

Immobility is a risk factor for thrombosis due to low blood flow, which may result in activation of the coagulation system, recruitment of platelets and clot formation. Nevertheless, hibernating animals—who endure lengthy periods of immobility—do not show signs of thrombosis throughout or after hibernation. One of the adaptations of hemostasis in hibernators consists of a rapidly reversible reduction of the number of circulating platelets during torpor, i.e., the hibernation phase with reduction of metabolic rate, low blood flow and immobility. It is unknown whether these platelet dynamics in hibernating hamsters originate from storage and release, as suggested for ground squirrel, or from breakdown and de novo synthesis. A reduction in detaching forces due to low blood flow can induce reversible adhesion of platelets to the vessel wall, which is called margination. Here, we hypothesized that storage-and-release by margination to the vessel wall induces reversible thrombocytopenia in torpor. Therefore, we transfused labeled platelets in hibernating Syrian hamster (Mesocricetus auratus) and platelets were analyzed using flow cytometry and electron microscopy. The half-life of labeled platelets was extended from 20 to 30 h in hibernating animals compared to non-hibernating control hamsters. More than 90% of labeled platelets were cleared from the circulation during torpor, followed by emergence during arousal which supports storage-and-release to govern thrombocytopenia in torpor. Furthermore, the low number of immature platelets, plasma level of interleukin-1α and normal numbers of megakaryocytes in bone marrow make platelet synthesis or megakaryocyte rupture via interleukin-1α unlikely to account for the recovery of platelet counts upon arousal. Finally, using large-scale electron microscopy we revealed platelets to accumulate in liver sinusoids, but not in spleen or lung, during torpor. These results thus demonstrate that platelet dynamics in hibernation are caused by storage and release of platelets, most likely by margination to the vessel wall in liver sinusoids. Translating the molecular mechanisms that govern platelet retention in the liver, may be of major relevance for hemostatic management in (accidental) hypothermia and for the development of novel anti-thrombotic strategies.

Intratumoral nanoplexed poly I:C BO-112 in combination with systemic anti-PD-1 for patients with anti-PD-1-refractory tumors.

Intratumoral therapies, especially Toll-like receptor agonists, can trigger both the innate and adaptive immune systems. BO-112 is a nanoplexed form of polyinosinic:polycytidylic acid (poly I:C) that induces local and systemic immunotherapeutic effects in mouse models. In a multicenter phase 1 clinical trial, repeated intratumoral administrations of BO-112 induced an increase in tumor cell necrosis and apoptosis, as well as augmented immune reactivity according to gene expression profiling. The first three cohorts receiving BO-112 as a monotherapy resulted in a recommended dose of 1 mg that could be safely repeated. Two grade 3 to 4 adverse reactions in the form of reversible thrombocytopenia were reported. In a fourth cohort of 28 patients with tumors that had primary resistance to anti-programmed cell death protein-1 (PD-1), the combination of intratumoral BO-112 with nivolumab or pembrolizumab was also well tolerated, and 3 patients (2 with melanoma and 1 with renal cell carcinoma) achieved partial responses, with 10 more patients having stable disease at 8 to 12 weeks. Thus, local BO-112 combined with a systemic anti-PD-1 agent might be a strategy to revert anti-PD-1 resistance.

Abstract 3021: Integrated pharmacokinetic (PK)/pharmacodynamic (PD) modeling leveraging PK, biomarker, and safety data to support dose and schedule selection for the BET inhibitor BMS-986158

Abstract Background: BMS-986158 is a potent, selective, and orally bioavailable small-molecule inhibitor of the bromodomain and extraterminal (BET) family of transcription modulators being evaluated in patients with various tumors in a phase 1 clinical study (NCT02419417). An integrated PK/PD analysis leveraging PK, biomarker, and safety data from the phase 1 study was performed to support dose and schedule (Sch) selection further clinical studies with BMS-986158. Methods: Five doses (0.75-4.5 mg) and 3 dosing regimens (Sch A: 5 days on, 2 days off over 21 days; Sch B: 14 days on, 7 days off; Sch C: 7 days on, 14 days off) were evaluated. Reversible thrombocytopenia (TTP) was the primary safety signal observed, and peripheral gene expression modulation was a PD biomarker indicative of drug target engagement. BMS-986158 serum PK was characterized with a 2-compartment population PK (PPK) model. A semimechanistic PK/PD model describing the platelet-reducing effect with BMS-986158 was developed to characterize platelet profiles for individual patients and to simulate and project the incidence of TTP at different doses and dosing regimens. The association of BMS-986158 exposure with expression modulation of select peripheral BET target genes, including HEXM1 and CCR2, was also examined. Results: BMS-986158 exhibited linear PK with rapid oral absorption (Tmax ≈ 2-4 h) and a terminal half-life of ≈ 60 h over the dose range of 0.75-4.5 mg. PPK modeling and simulation suggested that at the same dose level, Sch A led to comparable Cmax, with a higher Ctrough and Cavg at steady state compared with Sch B and C across the dosing interval. The semimechanistic PK/PD model predicted a higher incidence rate of TTP with Sch A than Sch C at the same dose level, and the predictions agreed with observed primary safety data from the phase 1 study. The model predicted grade 4 TTP incidence rates of 24% (95% CI, 21%-26%) and 43% (95% CI, 38%-45%) at 4.5 and 6 mg, respectively, with Sch A. This suggests that 4.5 mg would be the maximum tolerated dose, given that a 6 mg dose was predicted to exceed the target dose-limiting toxicity (DLT) rate of grade 4 TTP at 27%. The exploratory analysis of BMS-986158 exposure and expression of selected peripheral genes associated with the BET pathway suggested a direct association between BMS-986158 exposure and the magnitude of peripheral gene expression modulation. Conclusions: An integrated PK/PD analysis of BMS-986158 incorporating incidence of reversible TTP and modulation of peripheral BET target genes identified a maximum dose of 4.5 mg at Sch A for further clinical development. With the assumption that sustained gene expression modulation is desirable for BMS-986158 efficacy, Sch A, which provides sustained drug exposure, is recommended to enable continuous BET target gene expression modulation. Citation Format: Xi (Cindy) Chen, Lora Hamuro, Shodeinde Coker, John Hilton, Jennifer R. Diamond, Capucine Baldini, Mark Voskoboynik, Mihaela Cristea, William Edenfield, Kezi Unsal-Kacmaz, Donald Jackson, Abraham Apfel, Ke Xu, Li Zhu, Amit Roy, Akintunde Bello, Ronald Fleming, Paul Statkevich. Integrated pharmacokinetic (PK)/pharmacodynamic (PD) modeling leveraging PK, biomarker, and safety data to support dose and schedule selection for the BET inhibitor BMS-986158 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3021.

Abstract CT153: SDX-7320 elicits improvements in tumor-related and metabolic biomarkers: Results of a phase 1 dose-escalation study in patients with advanced refractory or late-stage solid tumors

Abstract Background and Rationale: Metabo-oncology is the study of specific tumor types whose growth and/or metastasis is accelerated by metabolic dysfunction, often associated with hyper-adiposity. In this setting the metabolic hormones leptin, adiponectin and insulin are potential mediators. SDX-7320 is a novel methionine aminopeptidase type 2 inhibitor (MetAP2) being developed for use in combination with other anti-cancer agents to treat the metabo-oncology patient population. Study Design: This first-in-human study used a 3+3 design with dose expansion at the RP2D. Measurements included standard assessments of safety, tolerability, as well as inhibition of MetAP2 in whole blood, plasma levels of protein biomarkers and drug exposure. Tumor response was measured using RECIST v.1.1. Results: 32 patients with an average of 5.3 prior treatment regimens were dosed. Sub-cutaneous dosing of SDX-7320 began at 1.7 mg/m2 once per week (Q7D, 28 days/cycle) and was escalated to 49 mg/m2. Repeated Q7D administration at 49 mg/m2 resulted in dose-limiting (G3-G4) thrombocytopenia. Expansion at 49 mg/m2 confirmed thrombocytopenia as the dose-limiting toxicity (DLT), reversible upon cessation of dosing. Dose-escalation was re-initiated at 36 mg/m2 every two weeks (Q14D). Repeated dosing at 65 mg/m2 (Q14D) resulted in G3 reversible thrombocytopenia. Expansion at 49 mg/m2 (Q14D) confirmed that this was the maximum tolerated dose (MTD) on a Q14D schedule. No deaths or Grade 5 TEAEs attributable to SDX-7320 were reported. Six patients had a combined total of 9 Grade 3/4 TEAEs considered by the Investigator to be at least possibly SDX-7320-related: thrombocytopenia (4 patients) and single cases of anemia, anorexia, fatigue, QTc prolonged, and vasculitis. Fourteen patients (44% had stable disease &amp;gt2 cycles and three patients had stable disease for ≥6 cycles. Inhibition of MetAP2 in whole blood was 100% at all doses evaluated while the time to reach 100% inhibition was inversely related to dose. When stratified for elevated baseline levels, the following biomarkers declined after initiating SDX-7320 (average of each patient's maximum % change relative to baseline +/- SD): bFGF (-53 +/- 76%), VEGF-C (-35 +/- 39%), and insulin (-55 +/- 30%). Without stratification, leptin levels declined (-51 +/-29%) and levels of adiponectin increased after SDX-7320 (+74 +/- 63% relative to baseline). Conclusions and Next Steps : SDX-7320 was well-tolerated with prolonged stable disease in an open-label, phase I first-in-human study. Improvements were observed in both tumor-related and metabolic biomarkers. Additional studies of SDX-7320 (in combination with other anti-cancer agents) in patients with solid tumors sensitive to metabolic hormones are scheduled. SDX-7320 is the first novel agent in clinical development to treat the metabo-oncology patient population. Citation Format: Monica M. Mita, Johanna Bendell, Alain C. Mita, Michael Gordon, Jasgit Sachdev, Bradley J. Carver, James Shanahan, Benjamin Mayes, Kris Awerkamp, David Browning, Neal Salomon, Kimberly Sullivan, Alfred Anderson-Villaluz, Joe Johnson, John S. Petersen, David J. Turnquist, Peter Cornelius. SDX-7320 elicits improvements in tumor-related and metabolic biomarkers: Results of a phase 1 dose-escalation study in patients with advanced refractory or late-stage solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT153.

Abstract 1742: Inhibition of BET signaling leads to reversible GATA1-associated repression of hematopoietic progenitors: translation from preclinical assessment to clinical development

Abstract Bromodomain and extraterminal (BET) proteins recognize acetylated lysine residues for the purpose of transcriptional regulation of genes, including those involved in stem cell renewal and oncogenes such as MYC. Inhibition of BET proteins BRD2, BRD3, BRD4, and BRDT represents a promising treatment option for patients with cancer. However, little is known about the consequence of BET inhibition on normal stem cell renewal processes, such as hematopoiesis. This study explored the mechanistic effects of BET inhibition on bone marrow (BM) hematopoiesis. Rats treated with BET inhibitors JQ1, BMS-X, or BMS-986158 for 4 days in vivo showed dose-dependent pan-cellular BM atrophy and reduction of hematopoietic progenitors of myeloid and erythroid lineage (combination of anti-rat CD45, CD11b, anti-granulocyte, CD71, anti-erythroid, and CD90 via flow cytometry) and consequential reductions in circulating platelet and reticulocyte counts, with complete reversibility within 10 days of stopping treatment with BET inhibitors. Primary rat BM stem and progenitor cells treated with BET inhibitors in vitro were evaluated with the colony-forming unit assay and resulted in dose-dependent reduction of multiple lineage progenitor colonies, especially the erythroid and megakaryocyte lineages. To further elucidate pathways involved in BET-related BM atrophy, erythropoiesis and thrombopoiesis genes regulated by GATA1, a BRD-associated transcription factor, from rat BM, as well as rat and human whole-blood samples exposed to BET inhibitor(s) were evaluated via RNAseq and RT-PCR. Dose-dependent responses in genes involved in erythropoiesis (Alas2, ABCme, PBG-D, HMBS) and thrombopoiesis (NFE2, PF4, GP1Bb, MPL) were observed after 4 days of treatment with BMS-986158. In a clinical trial (NCT02419417), patients with solid tumors treated with BMS-986158 demonstrated reversible thrombocytopenia and downregulation of NFE2, PF4, and HMBS expression, similar to that observed in rats. GATA1 was also downregulated in rat BM, with target engagement in rat and human demonstrated by the induction of HEXIM1 transcription, a pharmacodynamic (PD) biomarker of growth inhibition and apoptosis induced by BRD4 inhibition. Overall, our results suggest inhibition of BET signaling causes target-related, dose-dependent repression of hematopoietic progenitors through alterations of GATA1-associated erythropoiesis and thrombopoiesis regulation in rat BM and human blood samples, and these effects are reversible on cessation of BET inhibitor treatment. This is the first in vivo study demonstrating the mechanism of BET inhibition resulting in GATA1-associated repression of hematopoietic progenitors that is correlated to clinical pharmacokinetics and PD (Chen X, et al. AACR 2020) and is translatable from preclinical evaluation to clinical experience. Citation Format: Cindy Zhang, Ke Xu, Julie Panzica-Kelly, Jennifer Price, Denise Bounous, Shodeinde Coker, Kezi Unsal-Kacmaz, Danielle Greenawalt, Ashvinikumar Gavai, Ronald Fleming, Karen Augustine-Rauch, Richard Westhouse. Inhibition of BET signaling leads to reversible GATA1-associated repression of hematopoietic progenitors: translation from preclinical assessment to clinical development [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1742.

Preliminary Report of MANIFEST, a Phase 2 Study of CPI-0610, a Bromodomain and Extraterminal Domain Inhibitor (BETi), in Combination with Ruxolitinib, in JAK Inhibitor (JAKi) Treatment Naïve Myelofibrosis Patients

Preliminary Report of MANIFEST, a Phase 2 Study of CPI-0610, a Bromodomain and Extraterminal Domain Inhibitor (BETi), in Combination with Ruxolitinib, in JAK Inhibitor (JAKi) Treatment Naïve Myelofibrosis Patients

Abstract CT056: A Phase Ia/IIa trial of AVID100, an anti-EGFR antibody-drug conjugate

Abstract Background AVID100, a rationally designed anti-EGFR-DM1 conjugate, showed potent activity in preclinical models, including cancer cell lines resistant to approved anti-EGFR monoclonal antibodies. In addition, AVID100 showed increased toxicity on tumor cells compared to the unconjugated antibody. There was no increased AVID100-mediated toxicity on keratinocytes. Methods In the completed Phase Ia segment, 24 patients with advanced or metastatic epithelial malignancies without available standard of care therapy and likely to express EGFR were enrolled into sequential dose-escalation cohorts to assess safety, tolerability, pharmacokinetic (PK) parameters, and to identify the recommended Phase II dose (R2PD) of 2 hour infusions on an every 3 week schedule. In the ongoing Phase IIa segment, preliminary antitumor activity is being assessed in expansion cohorts of patients with high EGFR expression, including triple-negative breast cancer (TNBC) (2+ expression in ≥75% or 3+ in ≥50% of tumor cells) or either squamous cell carcinoma of the head and neck (SCCHN) or squamous non-small cell lung carcinoma (sqNSCLC) (3+ expression in ≥ 50% of tumor cells). The DAKO PharmDx assay was validated and used for screening intensity of EGFR protein expression. Results During Phase Ia, no Cycle 1 dose limiting toxicities (DLTs) were observed in Cohorts 1-6 at doses (N) of 20 (1), 40 (1), 80 (3), 120 (3), 180 (3), and 220 (6) mg/m2. In Cohort 7 (6) (270 mg/m2; ~ 7.3 mg/kg) two patients experienced Cycle 1 DLTs (G3 asymptomatic lipase elevation, G4 reversible thrombocytopenia), exceeding the maximally tolerated dose. A third patient developed G3 reversible pneumonitis. As a result, 220 mg/m2 (~6 mg/kg) was selected as the R2PD. Tumor types in greater than one patient included: colorectal (13), breast (4), and ovarian (2). Preliminary PK results at the R2PD revealed exposure exceeding preclinically predicted therapeutic levels. Cmax increased proportionally with dose, plasma half-life was ~50 hours at the R2PD, and clearance decreased with increasing doses with saturation observed between 180-270 mg/m2. Safety and tolerability were acceptable. Other treatment-related adverse events included: infusion-related reactions that were ameliorated by premedication and infusion prolongation, rash, nausea, vomiting, fatigue, headache, anorexia, mucositis, punctate keratitis, diarrhea, elevated amylase, reversible transaminase and alkaline phosphatase elevations without other evidence of hepatotoxicity, hypomagnesemia, and hypokalemia. Prolonged disease stabilization was observed in 3 of these patients not selected for EGFR overexpression (colorectal, ovarian, cervical). Conclusions AVID100 is a well-tolerated anti-EGFR-DM1 conjugate with evidence for exposure levels at or above those observed for cetuximab and ado-trastuzumab emtansine. Antitumor activity is currently being evaluated in EGFR-overexpressing patients in Phase IIa. Citation Format: Nehal Lakhani, Sreenivasa Chandana, Anthony Tolcher, Yvette Cole, Karla Rivas, Sandra Sinclair, Paul I. Nadler, Debra L. Wood, Kyri P. Papadopoulos. A Phase Ia/IIa trial of AVID100, an anti-EGFR antibody-drug conjugate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT056.

A CD117-Amanitin Antibody Drug Conjugate (ADC) Effectively Depletes Human and Non-Human Primate Hematopoietic Stem and Progenitor Cells (HSPCs): targeted Non-Genotoxic Conditioning for Bone Marrow Transplant

Current regimens for patient preparation, or conditioning, prior to bone marrow transplantation (BMT) limit the use of this curative procedure due to regimen-related mortality and morbidities. To address this, we developed a CD117-ADC to specifically deplete recipient HSPCs. CD117 is an ideal target for an ADC-based approach to patient preparation as it is selectively expressed on HSPCs. In addition, CD117 is frequently overexpressed on in acute myelogenous leukemia (AML). Thus, a CD117-ADC may enable curative treatment while potentially improving disease control prior to and following transplant. We developed a potent CD117 antibody conjugated to amanitin (AM), an RNA polymerase inhibitor, that depletes primary human CD34+ cells in vitro with an IC50 of 21pM (Fig. 1A). The ADC was designed to have a fast half-life, allowing the HSPC ablating ADC to clear prior to stem cell transplant. Humanized NSG mice treated with the anti-CD117-AM had >95% depletion of human HSPCs in bone marrow following a single dose of 0.1 mg/kg (Fig. 1B). The specificity of anti-CD117-AM was confirmed by the persistence of peripheral human lymphocytes, indicating the ability to maintain adaptive immunity. In addition, a single dose of anti-CD117-AM extended survival of NSG mice challenged with CD117+ patient derived xenografts (PDX), demonstrating potent anti-tumor effects. We treated NHPs with the cross-reactive anti-CD117-AM to determine if the ADC could deplete HSPCs in immune-competent animals. Dose-dependent decreases in phenotypic HSPCs and colony-forming units (CFUs) were observed in the bone marrow 7 days after dosing, with >95% HSPC depletion after a single dose of 0.3 mg/kg (Fig. 1C, 1D). Depletion was target- and AM-dependent, as the antibody alone and isotype-AM had no effect. In the periphery a transient decrease in reticulocytes was observed at day 4 with a neutrophil nadir at day 18. WBC and lymphocytes were within normal range throughout. Transient off-target effects consisted of reversible thrombocytopenia (Day 4-8) and reversible and mild liver enzyme levels (Day 4-10). Fractionated dosing achieved similar efficacy with reduced off-target effects. As expected, the fast half-life anti-CD117-AM was rapidly cleared (t1/215-18 h), providing appropriate pharmacokinetics for BMT. In summary, anti-CD117-AM can selectively deplete HSPCs in humanized NSG mice and NHP. In addition, the ADC exhibited potent anti-tumor activity in AML PDX models. This strategy could preserve the adaptive immune system with delayed onset of neutrophil nadir, potentially shortening the period of neutropenia during BMT. Targeted non-genotoxic conditioning with ADCs could provide a significant improvement to current approaches to patient preparation with an acceptable safety profile prior to BMT and gene therapies.

Anidulafungin induced reversible thrombocytopenia in a patient: A case report

Anidulafungin is a semisynthetic antifungal agent which is an echinocandin. Here, we presented elderly patient developed reversible severe thrombocytopenia due to anidulafungin. A 75-year-old man was admitted to the ICU with signs of hypovolemic shock and acute anemia. Amikacin therapy 15 mg/kg/day was started with the diagnosis of pneumonia due to the growth Acinetobacter baumannii. Amikacin therapy was discontinued in the treatment day 3 and began to colistin 2 mg/kg every 8 hours and imipenem 7 mg/kg every 6 hours. On hospital day 17, fluconazole 200mg/day was added to treatment due to candida albicans growth in blood culture and colistin-imipenem treatment was discontinued in the treatment. Candida albicans produced in control blood culture on floconazole therapy day 5 and the treatment was continued. Because of the increasing procalcitonin and CRP levels, liver enzyme elevation and fever 38.5 Co on fluconazole therapy day 6, anidulafungin therapy 200 mg was switched on fluconazole promptly. The dosage of anidulafungin was continued to 100 mg/day. Platelet counts was found to be six thousands anidulafungin therapy day 4. So treatment was terminated and liposomal amphotericin B treatment was started. Five days after the cessation of treatment with anidulafungin, platelets value was found to be over 100 thousand. Antifungal therapy was discontinued on liposomal amphotericin B therapy day 14, due not to the growth of microorganism in control blood culture. The patient who continue to be treated in intensive care, died due to multiorgan failure at 66 days. In conclusion; clinicians may consider monitoring platelets periodically, particularly in patients with hematologic disorders who use antibiotics and / or antifungal agents.

Short-Infusion Trabectedin in Heavily Pretreated Ovarian Cancer Patients: A Single-Institution Experience

Objective: The aim of this study was to assess the efficacy and tolerability of trabectedin given every 10 days as a single agent in recurrent ovarian cancer after 3 prior regimens. Method: Trabectedin 0.6 mg/m² was administered as a 3-h infusion every 10 days on a 21-day cycle. The study population was compared to patients treated with weekly paclitaxel 80 mg/m² intravenously on days 1, 8, 15, and 22 every 4 weeks. Results: We identified 34 patients previously submitted to at least 3 lines of chemotherapy who received single-agent trabectedin between 2010 and 2015. They were matched with a historical series of 34 patients who received weekly paclitaxel. No significant differences in response rate were found. Median progression-free survival was 4 months; 5 months in the trabectedin group and 4 months in the paclitaxel group. Overall survival (OS) was 13 months for the trabectedin group and 7 months for the paclitaxel group (p = 0.015). Patients who received platinum after trabectedin had a significant OS increase compared to those who received platinum after paclitaxel (18 vs. 9 months, respectively; p = 0.009). The most frequent drug-related grade 3/4 toxicities were reversible hepatic toxicity, neutropenia, anemia, thrombocytopenia, and gastrointestinal toxicity. Conclusion: Single-agent trabectedin every 10 days is an active treatment with a manageable toxicity profile in heavily pretreated advanced relapsed ovarian cancer patients.