Early Signs Of Antitumor Activity Research Articles

Updated results from first-in-human phase 1 dose-escalation trial of TAK-102, a GPC3-targeted armored CAR T cells, in patients with advanced solid tumors.

2543 Background: Glypican 3 (GPC3) is a member of the glypican family of heparan sulfate proteoglycans that are attached to the cell surface by a glycosylphosphatidylinositol anchor. High GPC3 expression rates are reported in numerous cancer types with a high unmet medical need, including hepatocellular carcinoma (HCC). TAK-102 is a GPC3-targeted autologous chimeric antigen receptor T cell (CAR-T) immunotherapy armored with IL-7 and CCL19. The addition of IL-7 and CCL19 to the construct was designed to support the expansion of memory subsets and persistence of CAR-T cells. We hypothesized TAK-102 would help overcome the challenges associated with an immunosuppressive tumor microenvironment that limit the activity of nonarmored CAR-T therapies in solid tumors. Methods: The first-in-human, Phase 1 dose escalation study evaluated TAK-102 in patients (pts) with GPC3-expressing solid tumors who were refractory or intolerant to standard treatments. TAK-102 was administered via a single infusion to 3 dose cohorts after lymphodepleting chemotherapy (LDC; consisting of fludarabine and cyclophosphamide): dose level (DL) 1 (starting cohort), 1x107 CAR+ cells/body; DL2, 1x108 CAR+ cells/body; DL3, 5x108 CAR+ cells/body. Objectives included evaluation of safety, dose-limiting toxicity (DLT), recommended phase 2 dose, cellular kinetic (CK) parameters, tumor markers, cytokine/chemokine and antitumor activity based on RECIST 1.1. Results: Eleven pts were enrolled and infused TAK-102 (DL1: 3 pts, DL2: 3 pts, DL3: 5 pts): 1 gastric neuroendocrine carcinoma, 2 liposarcoma, 8 HCC. Five pts achieved stable disease (SD), HCC (GPC3 H-Score: 36) . In patients achieving SD, the greatest reduction in tumor size was 26.4%. No DLTs or neurotoxicity were observed. Six pts experienced cytokine release syndrome (Grade1: 5 pts, Grade2: 1 pt); all cases were manageable. AFP was measured as a tumor marker for HCC. Among 8 pts with HCC, 4 had SD after treatment with TAK-102 and 3 showed a decrease or stabilization of AFP levels corresponding to their clinical status. CK profiles for pts were assessed by flow cytometry and qPCR-based assays. Overall, there was improvement in TAK-102 exposure (Cmax, AUC) when escalating from DL1 to DL2. There was a slight decrease in Tmax from DL2 to DL3. Homeostatic cytokine (IL-7) spiked post-LDC and showed no further increase after TAK-102 infusion across all the DLs. There was dose-dependency observed in peak CCL19, IFN-γ and IL-6 levels. Conclusions: TAK-102, an armored CAR-T, is well tolerated and has a manageable safety profile with some early signs of anti-tumor activity. For CK, TAK-102 exposure (Cmax, AUC) showed improvement from DL1 to DL2, and slight decrease in Tmax from DL2 to DL3. Dose-dependency was observed in peak CCL19, IFN-γ and IL-6 levels, which may point towards increased signal of activity from DL1 to DL3. Clinical trial information: NCT04405778 .

Safety, pharmacokinetics (PK), pharmacodynamics (PD) and efficacy of KT-253, a targeted protein degrader of MDM2, in patients with relapsed/refractory (R/R) solid tumors, lymphoma, high grade myeloid malignancies and acute lymphoblastic leukemia (ALL).

3084 Background: The tumor suppressor p53 is mutated in approximately 50% of cancers. In those cancers with wild-type p53, its activity is controlled by mouse double minute 2 (MDM2), an E3 ligase that tags p53 for degradation. KT-253 is a novel, highly potent heterobifunctional MDM2 degrader that upregulates p53 activity and overcomes the p53-MDM2 feedback loop, resulting in >200-fold higher potency compared to MDM2 inhibitors. In preclinical PDX models of sensitive p53WT solid tumors, AML and ALL, KT-253 robustly activates p53, induces apoptosis, and results in tumor regressions with every 3-week dosing. The ability to rapidly induce an acute apoptotic response and dose intermittently may result in a therapeutic index that has eluded previous MDM2 targeting agents. Methods: The ongoing open-label Phase 1 study evaluates safety, PK, PD and preliminary efficacy of IV KT-253 administered on Day 1 of 21-day cycles. Patients (pts) with advanced (≥2 prior therapies) solid tumors (ST)/lymphomas (Arm A) and relapsed/refractory (R/R) high grade myeloid malignancies (AML, high/very-high risk myelodysplastic syndrome (MDS), MDS/myeloproliferative neoplasms) and ALL (Arm B) are eligible. Blood samples are collected for KT-253 PK/PD analyses. Results: As of 26 January 2024, 18 pts have been treated, 13 in Arm A dose levels (A: DL) 1-4 and 5 in Arm B dose levels (B: DL) 1-2, with mean number of 3 and 2 doses, respectively. The most common solid tumor types were Merkel cell carcinoma ((MCC) n=3), adenoid cystic carcinoma ((ACC) n=2) and uveal melanoma (n=2). Arm B included 5 pts with R/R AML. The median age was 61 years (yrs) (range 42, 81) in Arm A and 66 yrs (range 57, 70) in Arm B. The most common adverse events (AEs) in > 20% of pts included nausea, fatigue, headache, and vomiting. There was 1 DLT of AEs leading to discontinuation that included Grade (G) 2 nausea and fatigue in A: DL4. There were no neutropenia or thrombocytopenia AEs in either arm. KT-253 related SAEs included G3 hypotension in a pt with decreased oral intake (A: DL1). Overall best response: 1 CR (B: DL2, AML); 2 PRs (A: DL1, MCC; B: DL1, AML); 3 SD (A: DL1, fibromyxoid sarcoma; DL2, ACC; DL3, renal cell cancer). PD data from A: DL1-4 and B: DL1-2 demonstrated rapid upregulation of plasma GDF-15 protein and upregulation of CDKN1A and PHLDA3 mRNA levels in blood. KT-253 demonstrated dose-dependent increase in plasma exposure with levels approximating efficacious doses. Conclusions: KT-253 results in potent upregulation of p53-dependent biomarkers and has demonstrated early signs of anti-tumor activity including objective responses in MCC and AML at doses that are well tolerated. Dose escalation is ongoing at DL4 in Arm A and at DL2 in Arm B and analyses from additional pts will be presented at the meeting. Clinical trial information: NCT05775406 .

Abstract SY12-01: Targeting validated but un-drugged oncogenes with small molecule protein degraders

Abstract SY12-01: Targeting validated but un-drugged oncogenes with small molecule protein degraders

The HER2-directed antibody-drug conjugate DHES0815A in advanced and/or metastatic breast cancer: preclinical characterization and phase 1 trial results

Approved antibody-drug conjugates (ADCs) for HER2-positive breast cancer include trastuzumab emtansine and trastuzumab deruxtecan. To develop a differentiated HER2 ADC, we chose an antibody that does not compete with trastuzumab or pertuzumab for binding, conjugated to a reduced potency PBD (pyrrolobenzodiazepine) dimer payload. PBDs are potent cytotoxic agents that alkylate and cross-link DNA. In our study, the PBD dimer is modified to alkylate, but not cross-link DNA. This HER2 ADC, DHES0815A, demonstrates in vivo efficacy in models of HER2-positive and HER2-low cancers and is well-tolerated in cynomolgus monkey safety studies. Mechanisms of action include induction of DNA damage and apoptosis, activity in non-dividing cells, and bystander activity. A dose-escalation study (ClinicalTrials.gov: NCT03451162) in patients with HER2-positive metastatic breast cancer, with the primary objective of evaluating the safety and tolerability of DHES0815A and secondary objectives of characterizing the pharmacokinetics, objective response rate, duration of response, and formation of anti-DHES0815A antibodies, is reported herein. Despite early signs of anti-tumor activity, patients at higher doses develop persistent, non-resolvable dermal, ocular, and pulmonary toxicities, which led to early termination of the phase 1 trial.

Abstract PR013: First-in-human dose-expansion study of NBF-006, a novel investigational siRNA targeting GSTP, in patients with KRAS-mutated non-small cell lung cancer

Abstract Background Glutathione S-transferase Pi (GSTP) has an important role in detoxification and anti-oxidative damage response. Additionally, GSTP has a chaperone function which regulates key oncogenic pathways such as the KRAS and JNK. Since alternative or redundant pathways could compensate for the inhibition of a single kinase, targeting multiple pathways could lead to more effective therapy. NBF-006 is a novel drug product comprised of GSTP siRNA encapsulated within a proprietary lipid nanoparticle. It is designed to deliver siRNA to localized and metastatic lung tumors. As GSTP downregulation leads to inhibition of KRAS signaling through modulation of both MAPK and PI3K pathways, NBF-006 is being developed to treat KRAS mutant tumors. NBF-006-001 is a first-in-man dose escalation (Part A) and expansion (Part B) study evaluating safety, tolerability, PK, and preliminary efficacy of NBF-006 administered intravenously over 70 minutes, QW4 followed by a 2-week rest period. Part A of the study enrolled 21 patients with advanced non-small cell lung cancer (NSCLC), pancreatic, or colorectal cancer. No DLTs or treatment-related SAEs were observed. NSCLC disease control rate of 55% (6/11) was observed in heavily pre-treated patient population, warranting further investigations. Results from advanced KRAS-mutated NSCLC patients enrolled in NBF-006-001 are reported here. Results Thirty-four KRAS-mutated NSCLC patients received treatment at 0.6 mg/kg [n=12], 1.2 mg/kg [n=11], or 1.6 mg/kg [n=11]. NBF-006 was well tolerated with no treatment-related grade 4-5 AEs, SAEs, or DLTs. Two grade 3 events were assessed as possibly related to study treatment, anemia and bilateral pleural effusions (both at 0.6 mg/kg). The most common (>10 % of patients) NBF-006-related AEs were Grade 1 or 2 infusion related reactions (low grade IRRs) (20.6 %) and nausea (11.8 %). There was no dose relationship in the number of AEs or any observed AEs. Low grade IRRs (n=8 in seven patients), occurred in the first cycle of therapy and were generally well-managed. Only one patient discontinued study therapy due to recurring IRR. Substantial cytokine elevation was only noted in this patient. No clinically meaningful complement activation nor ADA response has been observed. PK analysis indicated a mean terminal half-life of 41 (± 13) hours with no accumulation. Cmax and AUC demonstrated dose-proportionality up to 1.2 mg/kg and no apparent increase in exposure at 1.6 mg/kg. Patients had received 1-7 prior lines of therapy (average 2.6; 1 line [n=10], 2 lines [n=9], and ≥ 3 lines [n=15] respectively). Two patients (treated at 1.2 and 1.6 mg/kg) experienced a durable PR, 14 patients experienced SD. One patient with PR and one patient with a mixed response stayed on study for >12 months. Conclusion The expansion part of the NBF-006-001 study confirmed the favorable safety profile of NBF-006 and demonstrated early signs of antitumor activity in KRAS-mutated NSCLC. The results suggest that further clinical development of NBF-006, alone or in combination with standard therapy, is warranted. Citation Format: Hirva Mamdani, Alberto Chiappori, Lyudmila Bazhenova, Alexander Spira, Wade Iams, Minal Barve, Anthony W Tolcher, Eli Gabayan, Andrae Vandross, Annie Huynh, Yael Cohen-Arazi, Zachary Albaugh, Joachim Gullbo, Sonya Zabludoff. First-in-human dose-expansion study of NBF-006, a novel investigational siRNA targeting GSTP, in patients with KRAS-mutated non-small cell lung cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr PR013.

Preliminary Safety, Pharmacokinetics, Pharmacodynamics and Clinical Activity of KT-333, a Targeted Protein Degrader of STAT3, in Patients with Relapsed or Refractory Lymphomas, Large Granular Lymphocytic Leukemia, and Solid Tumors

Background: KT-333is a first-in-class, potent, highly selective, heterobifunctional small molecule degrader of the signal transducer and activator of transcription 3 (STAT3) protein. Aberrant activation of STAT3 resulting from activating mutations or deregulated cytokine signaling underlies various malignancies including peripheral T-cell lymphomas (PTCL), cutaneous T-cell lymphoma (CTCL), and large granular lymphocytic leukemia (LGL-L). Approximately 70% of human cancers including hematological malignancies and solid tumors exhibit increased levels of phosphorylated STAT3 (pSTAT3), a biomarker of pathway activation. In non-clinical studies, treatment with KT-333 resulted in durable tumor regressions with weekly (QW) or once every two weeks IV administration in STAT3-dependent T cell lymphomas. STAT3 degradation also sensitized immunocompetent mouse models of solid and liquid cancers to anti-PD1(ASH 2021, SITC 2021). Methods: The ongoing open-label, Phase 1a/1b study is evaluating the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and preliminary clinical activity of KT-333 administered as a QW IV infusion on Day 1, 8, 15 and 22 (28-day cycle) in patients (pts) with B- and T-cell lymphomas, Hodgkin's lymphoma and advanced solid tumors (ST) relapsed/refractory (R/R) to at least two prior systemic therapies and LGL-L and T-cell prolymphocytic leukemia R/R to at least one prior therapy. Cycle 1 and 2 blood samples are collected for KT-333 plasma concentrations and to measure changes in STAT3 protein expression in peripheral blood mononuclear cells (PBMCs) using targeted mass spectrometry. Whole blood RNA sequencing measures mRNA levels of STAT3 regulated targets. Plasma levels of inflammatory biomarkers are measured with Luminex. STAT3 degradation and other related biomarker changes in tumor are assessed in patients with accessible tumors. (NCT05225584). Results: As of July 10, 2023, 21 pts were treated at five dose levels (DL) in Phase 1a with a mean number of 5.8 doses. Pts included B-cell non-Hodgkin's lymphoma (n=1: DL5), Hodgkin's lymphoma (HL) (n=1: DL4), CTCL (n=3: DL1, 2 and 4), PTCL (n=1: DL2), LGL-L (n=2: DL5) and ST (n=13: DL1-4) with median age of 61 years (range 30,77) and ECOG performance status of 0 (n=7) or 1 (n=14). No DLTs and no KT-333 related serious adverse events (SAE) were reported. The most common AEs were Grade 1 and 2 and included constipation, fatigue, nausea and anemia. Best response among pts evaluable for response at data cut-off (not including CTCL or HL pts at DL4 or any DL5 pts) included one partial response after two cycles in a CTCL pt at DL2 and SD after two cycles in three ST pts treated at DL3 and DL4. PD data in blood available for DL1-4 demonstrated robust, dose-dependent, and sustained STAT3 degradation in PBMC. The mean maximum degradation of STAT3 by targeted mass spectrometry over the first two weeks in Cycle 1 by DL was (% (range; n)): DL1: 69.9% (52.6% to 84.1%; n=4), DL2: 73.5% (65.5% to 80.7%; n=3), DL3: 79.9% (72.3% to 90.4 %; n=3) and DL4: 86.6% (78.9% to 95.9 %; n=4) with absolute quantification of STAT3 peptides falling below lower limit of quantification of the assay for one pt in DL3 and two in DL4. STAT3 pathway inhibition in blood was demonstrated via transcriptional downregulation of a canonical JAK/STAT3 target, SOCS3, which correlated with changes in STAT3 protein levels. KT-333 also resulted in dose-dependent downregulation of STAT3-regulated inflammatory biomarkers C-reactive protein and serum amyloid A protein in plasma. KT-333 demonstrated linear PK with plasma exposure increasing with dose and reaching levels close to those predicted to be efficacious. Conclusion: The emerging clinical data demonstrate that KT-333 is a potent degrader of STAT3 as demonstrated in PBMCs at doses that are well tolerated. These data provide the first evidence of STAT3 targeted protein degradation in humans with associated STAT3 pathway inhibition, along with potential early signs of antitumor activity, highlighting the potential of heterobifunctional degraders for targeting previously undruggable transcription factors implicated in diseases. Based on non-clinical data and PK/PD modeling, the high levels of degradation achieved so far are expected to be clinically efficacious in STAT3-dependent malignancies. Accrual is ongoing, and analyses from additional patients will be presented at the meeting.

First-in-human dose-escalation study of NBF-006, a novel investigational siRNA targeting GSTP, in patients with non-small cell lung, pancreatic, or colorectal cancer.

3084 Background: Glutathione S-transferase Pi (GSTP) has an important role in detoxification and anti-oxidative damage response. Additionally, GSTP has a chaperone function which regulates key oncogenic pathways such as the KRAS and JNK pathways. Targeting multiple pathways could lead to more effective therapy than agents inhibiting single downstream kinase pathways (i.e., a MEK inhibitor), as alternative or redundant pathways could compensate for the inhibition of a single kinase. NBF-006 is a novel drug product containing a GSTP siRNA encapsulated within a lipid nanoparticle. It has been designed to deliver siRNA to tumors of the lung and common sites of metastatic spread (liver and marrow) which has been demonstrated in preclinical efficacy models. Methods: NBF-006-001 is a first-in-man (FIM) dose escalation study evaluating safety, tolerability, and PK of NBF-006 administered intravenously over 70 minutes, QW4 followed by a 2-week rest period in patients with advanced non-small cell lung (NSCLC), pancreatic (PANC), or colorectal cancer (CRC). Results: Twenty-one patients (11 NSCLC, 5 CRC, and 5 PANC) received treatment in a standard 3+3 dose escalation design (0.15 mg/kg [n=2], 0.3 mg/kg [n=3], 0.6 mg/kg [n=3], 1.2 mg/kg [n=6], and 1.6 mg/kg [n=7]). NBF-006 was well tolerated with no treatment-related grade 4-5 AEs, SAEs nor DLTs. Only one grade 3 event (WBC decrease) was assessed as possibly related. The most common NBF-006-related AEs were Grade 1 or 2 arthralgia, diarrhea, fatigue, and vomiting (11% each). There was no dose relationship in the number of AEs or any observed AEs. No meaningful complement activation, cytokine elevation nor ADA response has been observed to date (20 patients). One patient had 2 infusion related reactions (Grade 1 and 2). PK analysis indicated a terminal half-life ranging from 26 to 55 hours with no accumulation. Cmax and AUC demonstrated dose-proportionality up to 1.2 mg/kg and no additional increase in exposure at 1.6 mg/kg. NSCLC patients had an average and median number of prior lines of therapy of 4 and 3, respectively, with a range from 1-7 prior lines. One patient with NSCLC (treated at 1.6 mg/kg) experienced a durable partial response and progressed after ten months on the study. Four additional patients with NSCLC experienced stable disease, and two of these stayed on study treatment for >6 months (both treated at 1.2 mg/kg). One patient remains on treatment. CRC and PANC patients had an average/median of 4 and 3 prior lines, respectively. In CRC and PANC, stable disease for 24 weeks was the best response (n=1 each). Conclusions: This FIM study with NBF-006 demonstrated a favorable safety profile with early signs of antitumor activity in NSCLC. No DLTs or treatment-related SAEs were observed. Dose expansion in NSCLC is ongoing and will not be presented. Clinical trial information: NCT03819387 .

453O DS-7300 (B7-H3 DXd antibody-drug conjugate [ADC]) shows durable antitumor activity in advanced solid tumors: Extended follow-up of a phase I/II study

B7-H3 overexpression correlates with poor prognosis in many cancers. DS-7300 is a B7-H3–directed ADC with a topoisomerase I inhibitor payload (DXd). The DS-7300 dose finding study (NCT04145622) showed that DS-7300 was generally well tolerated with early signs of antitumor activity. We present extended follow-up data for a larger cohort of participants (pt) with selected tumor types.

Intratumoral administration of CD1c (BDCA-1)+ and CD141 (BDCA-3)+ myeloid dendritic cells in combination with talimogene laherparepvec in immune checkpoint blockade refractory advanced melanoma patients: a phase I clinical trial

BackgroundIntratumoral (IT) myeloid dendritic cells (myDCs) play a pivotal role in initiating antitumor immune responses and relicensing of anti-tumor cytotoxic T lymphocytes within the tumor microenvironment. Talimogene laherparepvec (T-VEC) induces...

Abstract 1363: Preclinical development of bispecific CAR-T cells for canine B cell malignancies

Abstract Chimeric antigen receptor (CAR)-T cells targeting CD19 have revolutionized the treatment of B cell malignancies in people. However, post-treatment loss of CD19 has emerged as an adaptive mechanism of resistance. Pet dogs that develop tumors spontaneously in an immune competent setting represent a compelling parallel population of patients to study next generation cancer immunotherapies. Comparative trials at the University of Pennsylvania are investigating the activity of canine CAR-T cells targeting either CD19 or CD20 in canine B cell lymphoma patients and have revealed a favorable safety profile with early signs of anti-tumor activity. Aligned with experiences in human trials, expansion of CD20-negative B cells has been observed in dogs treated with anti-CD20 CAR-T cells. Bispecific CAR-T cells that simultaneously target two antigens to mitigate antigen escape have encouraging efficacy profiles in human patients. Thus, we designed a dual-targeting CAR specific for canine B cell antigens. A second-generation canine CAR construct targeting both CD19 and CD20 with a 28z signaling domain was cloned into the MSGV1 backbone. Chimeric retrovirus encoding RD114 and VSV-G envelope proteins and the CAR construct was made using GP2-293 cells. Jurkat NFAT-GFP reporter cells and primary T cells from dogs diagnosed with high grade B cell lymphoma were retrovirally transduced with bispecific CARs. Antigen specific reactivity was assessed against cell lines with variable CD19 and CD20 expression patterns. The CD19-CD20 CAR was efficiently transduced, with stable expression in both Jurkat and primary canine T cells. Jurkat reporters revealed dual-specific CAR signaling after co-culture with CD19+ and/or CD20+ target cells. Primary canine CAR-T cells expanded in vitro and exhibited CAR-specific proliferation and cytotoxicity against CD19+ CD20+ target cells. Preclinical manufacture of functional, bispecific anti-CD19 anti-CD20 canine CAR-T cells is feasible. A clinical trial recruiting dogs diagnosed with B cell cancer will assess safety and efficacy of this approach in vivo, with the aim of establishing the dog as a compelling model to appraise the ability of bispecific CAR-T cells to overcome therapeutic failures secondary to antigen loss. Citation Format: Matthew J. Atherton, Antonia Rotolo, Nicola J. Mason. Preclinical development of bispecific CAR-T cells for canine B cell malignancies [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 1363.

A phase Ia/Ib, dose-escalation/expansion study of BI 907828 in combination with BI 754091 (ezabenlimab) and BI 754111 in patients (pts) with advanced solid tumors.

3095 Background: Preclinical data show that combining a murine double minute 2–tumor protein 53 (MDM2–p53) antagonist with immune checkpoint inhibitors produces anti-tumor effects in multiple tumor types. This Phase Ia/Ib study (NCT03964233) is assessing BI 907828, a MDM2–p53 antagonist, combined with immune checkpoint inhibitors in TP53 wild-type cancers. Methods: In Phase Ia (dose escalation), pts with advanced/metastatic solid tumors received escalating doses of BI 907828 guided by a Bayesian Logistic Regression Model (starting dose 10 mg orally) plus ezabenlimab 240 mg (anti-PD-1 antibody) and BI 754111 600 mg (anti-LAG-3 antibody) every 21 days (q3w). Primary endpoint was the maximum tolerated dose (MTD) of BI 907828 based on the number of pts with dose-limiting toxicities (DLTs) during cycle one. During Phase Ia, other studies indicated a lack of added efficacy when BI 754111 was combined with ezabenlimab; therefore, the study design was updated to switch the dose escalation to the doublet combination of BI 907828 plus ezabenlimab. Results: A total of 11 pts received the triplet combination at 10/20/30/45 mg dose levels (DL; n = 3/3/3/2 respectively); all have discontinued treatment. No DLTs were reported in cycle one; MTD was not reached. As of 20th January 2022, 15 pts have received the doublet combination at 30/45 mg DLs (n = 10/5 respectively). One pt (45 mg) had a DLT during cycle one: G2 neutropenia. Four DLTs were reported after cycle one: G3 anemia (30 mg); G2 thrombocytopenia (45 mg); and G3 neutropenia and G4 thrombocytopenia (45 mg). G≥3 adverse events occurred in eight pts; most commonly anemia (n = 6), thrombocytopenia (n = 4) and lymphopenia (n = 3). There were no notable safety findings with BI 907828 45 mg q3w, the recommended dose for expansion (RDE) for BI 907828 monotherapy. Nine of the 15 pts who received doublet therapy were evaluable for response; four had a confirmed partial response (PR; 30 mg, n = 1; 45 mg, n = 3), two biliary tract carcinoma, one urothelial carcinoma, and one myxoid liposarcoma; one had an unconfirmed PR (30 mg) with adenocarcinoma (primary site intrahepatic cholangiocarcinoma). Four pts with liposarcoma and gastric cancer had stable disease. MTD will be reported. In Phase Ib, pts will receive the RDE of BI 907828 plus 240 mg ezabenlimab (q3w). Pts will be recruited to two cohorts: soft tissue sarcomas (liposarcoma, undifferentiated pleomorphic sarcoma, myxofibrosarcoma, synovial sarcoma and leiomyosarcoma) and selected MDM2-amplified tumors (NSCLC, gastric adenocarcinoma, urothelial carcinoma, and biliary tract carcinoma). Primary endpoints are progression-free survival and objective response (RECIST 1.1). Conclusions: The doublet combination of BI 907828 plus ezabenlimab showed a manageable safety profile and early signs of anti-tumor activity. Eleven pts remain on treatment; recruitment is ongoing. Clinical trial information: NCT03964233.

Abstract P5-17-08: A phase Ib/II study of leronlimab combined with carboplatin in patients with CCR5+ metastatic triple-negative breast cancer (mTNBC)

Abstract Background C-C Chemokine Ligand type-5 (CCR5) is overexpressed in >95% of TNBC and has been correlated with disease progression. Moreover, enhancement of DNA repair signaling by CCR5 activation may contribute to chemotherapy resistance. Therefore, blocking CCR5 may result in increased immune response against tumor cells and synergize with chemotherapy. Leronlimab (PRO 140) is a humanized monoclonal antibody to CCR5. Preclinical data showed leronlimab binds human CCR5, blocks CCR5-mediated signaling, and CCL5-induced breast cancer cell invasion. The therapeutic antibody leronlimab has been administered to over 800 healthy and HIV-1 infected individuals with good tolerance and without obvious dose-related toxicity, making it an ideal partner for chemotherapy combinations in TNBC. Methods In this ongoing phase 1B/2 study, patients with CCR5+ mTNBC with ≤2 line of therapy in the metastatic setting (no prior carboplatin) are treated with weekly subcutaneous leronlimab (3 dose levels, 3+3 dose escalation) and a fixed dose of carboplatin AUC 5 on day 1 with a 21-day dose-limiting toxicity (DLT) window, followed by expansion in 30 patients with CCR5+ mTNBC who are naïve to chemotherapy in the metastatic setting or who have failed first-line combination of chemotherapy (excluding carboplatin) and a checkpoint inhibitor in the metastatic setting. CCR5 positivity is centrally assessed by IHC and defined as >10% CCR5 staining in primary or metastatic tumor cells and/or high predominance of CCR5+ tumor-infiltrating leukocytes (TIL). Primary objectives are safety, tolerability, determination of maximum tolerated dose, and determination of the recommended phase 2 dose (RP2D). Results Fifteen patients had archived tumor tissue assessed for CCR5 expression, with 12 being CCR5 positive (median expression 20%, range 0 - 100%, and 7 out of 12 high CCR5+ TILs) . A total of ten patients (median age 51 years; median 2 prior therapies) have been enrolled at 3 dose levels (350, 525, and 700 mg). In the second cohort, 1 additional patient was inadvertently enrolled. All patients completed the DLT assessment period and no DLTs have been observed. Patients received between 3 and 27 doses of leronlimab with the number of cycles ranging from 1 to 9. Five patients remain on treatment. The most common treatment-emergent adverse events (TEAEs) by any grade were: fatigue (6/10), headache (4/10), constipation (3/10), and nausea (3/10). The following grade ≥3 TEAEs were reported: neutropenia, anemia, thrombocytopenia, hyponatremia, hypertension, diarrhea and headache. Serious Adverse Events were reported in 2 patients (grade 2 sepsis and grade 3 headache). The following leronlimab treatment related adverse events (TRAEs) occurred (all grade 1): injection site reaction in cohort 1, fatigue (n=2) and headache in cohort 2. Three carboplatin TRAEs ≥3 were reported in one patient in cohort 1: thrombocytopenia, anemia and leukopenia. Two out of seven patients eligible for response achieved a confirmed partial response, and 4 patients stable disease. Conclusions Leronlimab, in combination with carboplatin, has been well-tolerated in all 3 dose levels with early signs of anti-tumor activity in patients with CCR5+ mTNBC. The study is currently enrolling patients at the RP2D dose of leronlimab 700mg in combination with carboplatin AUC 5 in the phase 2 part of the trial. Clinical trial information: NCT03838367 Citation Format: Massimo Cristofanilli, Namita Chittoria, Sima Ehsani, Hallgeir Rui, Milana Dolezal, Lisette Stork-Sloots, Femke de Snoo, Christopher Recknor, Vandana Abramson. A phase Ib/II study of leronlimab combined with carboplatin in patients with CCR5+ metastatic triple-negative breast cancer (mTNBC) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-17-08.

Abstract P1-18-17: Phase I study of cfi-402257, an oral ttk inhibitor, in patients with advanced solid tumors with breast cancer expansion cohorts

Abstract Background: TTK (also known as Mps1), a dual-specificity serine-threonine kinase, is critical for the spindle assembly checkpoint (SAC), chromosome alignment and error correction in mitosis. Inhibition of TTK causes premature mitotic exit with unattached chromosomes, resulting in chromosomal missegregation, aneuploidy and cell death. CFI-402257 is a potent (Ki = 0.09 nM, IC50 = 1.2 nM), highly selective and orally active inhibitor of TTK. Robust suppression of tumor growth was achieved upon oral dosing of single agent CFI-402257 in ER+/HER2- and triple negative breast cancer (TNBC) cell line and patient derived xenograft models. CFI-402257 demonstrated enhanced cytotoxicity in CDK4/6 inhibitor resistant ER+ breast cancer cell line models compared to parental cell lines, including those with RB1 loss. Methods: This multi-center Phase I dose escalation study (3+3 design) was designed to determine the safety, tolerability and maximum tolerated dose (MTD) of CFI-402257 and evaluate anti-tumor activity at the RP2D. CFI-402257 was dosed once daily on a continuous schedule in 28-day cycles at a starting dose of 5mg based on preclinical toxicology. Dose escalation included patients with advanced solid tumors and dose expansion at the RP2D into three expansion cohorts - Cohort A advanced solid tumors, Cohort B advanced ER+ or TNBC with 1-4 prior lines of chemotherapy for metastatic disease and Cohort C ER+/HER2- breast cancer in combination with Fulvestrant (500mg IM Day 1, 15 and 29 and then every 28 days) who have had prior treatment with an aromatase inhibitor in combination with a CDK4/6 inhibitor (>= 3 months) and =<1 prior chemotherapy for metastatic disease. Results: As of May 25, 2021, 66 patients had been enrolled, majority (76%) of patients received >3 prior therapies before study entry and 37% of patients’ (23/66) primary malignancy was breast cancer. The maximum administered dose was 294 mg and the study has continued enrolling at the recommended phase 2 dose of 168 mg with grade 3 Neutropenia, grade 3 Febrile Neutropenia and grade 3 Colitis as the dose limiting toxicities. Only 1/6 patients experienced a DLT at 168 mg (grade 3 Neutropenia, >7 days) The most common treatment emergent AEs (Gd3, >5%) were Neutropenia (15.6%), Anaemia (7.8%), Hypophosphataemia and Febrile Neutropenia (6.3%). PR’s confirmed by the Investigator have been seen to date in 33% of the cohort C subjects (2/6 patients), with an additional two cPR’s seen in the breast cancer population (ER+/HER2-) from the expansion cohorts. Conclusion: CFI-402257 is generally well tolerated and continues to enroll at 168mg daily with a manageable AE profile and early signs of anti-tumor activity. Enrollment in the expansion cohorts is ongoing and updated safety and efficacy data for the previously treated ER+/HER2- population will be presented at the time of the meeting. A multi-center phase II clinical trial is planned. Citation Format: John Hilton, Daniel J Renouf, David W Cescon, Aaron R Hansen, Albiruni RA Razak, Lee-Anne Stayner, Trisha Denny, Graham Fletcher, Tak W Mak, Mark Bray, Philippe L Bedard. Phase I study of cfi-402257, an oral ttk inhibitor, in patients with advanced solid tumors with breast cancer expansion cohorts [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-18-17.

Investigational immunomodulatory drugs for enhancement of triple negative breast cancer (TNBC) immunotherapy: early phase development

ABSTRACT Introduction Immunotherapy through the blockade of PD1-PDL1 axis has shown to improve outcomes in advanced and early triple negative breast cancer (TNBC). To further enhance immune-stimulation, and ultimately improve patient outcomes, a wide variety of next-generation immunotherapies (NGIO) is being developed for this disease. Areas covered In the present article, we discuss the immune landscape of TNBC and recapitulate the rationale and available clinical evidence of NGIO under early phase development for TNBC, highlighting challenges and opportunities in this emerging field of research. Expert opinion Multiple immunotherapeutic strategies beyond PD-(L)1 blockade have been tested for TNBC, including the targeting of further inhibitory checkpoints, the agonism of costimulatory molecules, the intratumoral administration of immunotherapies and cancer vaccines. Most of these strategies have demonstrated to be safe in early clinical trials, with some exhibiting early signs of antitumor activity. To optimally harness the potential of NGIO, a refined patient selection based on emerging immune biomarkers will be required, through an adaptation of immunotherapeutic strategies based on patient and tumor characteristics. More mature data from ongoing clinical trials, added to the progressively increasing knowledge on breast cancer immune landscape, will hopefully clarify the role of NGIO for the treatment of TNBC.

First-in-human dose escalation of ALPN-202, a conditional CD28 costimulator and dual checkpoint inhibitor, in advanced malignancies.

2547 Background: Strong preclinical rationale has emerged for combining checkpoint inhibition (CPI) with T cell costimulatory agonists, particularly CD28, a critical T cell costimulatory molecule recently recognized as a key target of checkpoint inhibition. ALPN-202 is a variant CD80 vIgD-Fc fusion that mediates PD-L1-dependent CD28 costimulation and inhibits the PD-L1 and CTLA-4 checkpoints. It has demonstrated superiority to CPI-only therapies in tumor models, while demonstrating favorable safety in preclinical toxicology studies. Methods: This is a cohort-based, open-label dose escalation and expansion study of ALPN-202 in adults with advanced solid tumors or lymphoma (NCT04186637). Subjects with cancers refractory to standard therapies (including approved CPIs), or cancers without available standard or curative therapy are eligible. After two planned single-subject cohorts, a standard 3+3 dose escalation has been implemented with two dose schedules in parallel, Q1W and Q3W. Objectives include evaluation of safety and tolerability, PK, PD and preliminary anticancer activity of ALPN-202. Disease assessments are evaluated by RECIST v1.1 for solid tumors or by Lugano Classification for lymphoma. Results: As of January 2021, 20 subjects with advanced malignancies have received ALPN-202. Dose-dependent PK and target saturation have been preliminarily observed. So far, ALPN-202 has been well tolerated at dose levels ranging from 0.001 to 1 mg/kg weekly, with no DLTs. Low-grade skin toxicities (grade 1-2 rash) have been observed in 4 subjects (20%). Among 11 evaluable subjects, an unconfirmed partial response has been observed in one subject with colorectal carcinoma, while stable disease has been observed in 5 subjects with colorectal carcinoma, mesothelioma (2), cholangiocarcinoma, and renal cell carcinoma -- for a preliminary clinical benefit (PR+SD) rate of 100% (4/4) at dose levels of 0.3 mg/kg and higher, or 54% (5/11) overall (table). The meeting presentation will update this data, which is expected to include the conclusion of Q1W dose escalation, as well as immune correlates. Conclusions: First-in-human dose escalation with ALPN-202 has been well tolerated at doses capable of engaging CD28 costimulation in vivo in association with dual PD-L1/CTLA-4 checkpoint inhibition, with early signs of anti-tumor activity. These findings suggest that CD28 agonism can be safely achieved in humans, and further suggest that dose expansion with ALPN-202 is warranted to assess the relevance of controlled CD28 costimulation as a novel approach to cancer immunotherapy. Clinical trial information: NCT04186637. [Table: see text]

Chimeric Antigen Receptor-Glypican-3 T-Cell Therapy for Advanced Hepatocellular Carcinoma: Results of Phase I Trials.

Our preclinical studies demonstrated the potential of chimeric antigen receptor (CAR)-glypican-3 (GPC3) T-cell therapy for hepatocellular carcinoma (HCC). We report herein the first published results of CAR-GPC3 T-cell therapy for HCC. In two prospective phase I studies, adult patients with advanced GPC3+ HCC (Child-Pugh A) received autologous CAR-GPC3 T-cell therapy following cyclophosphamide- and fludarabine-induced lymphodepletion. The primary objective was to assess the treatment's safety. Adverse events were graded using the Common Terminology Criteria for Adverse Events (version 4.03). Tumor responses were evaluated using the RECIST (version 1.1). A total of 13 patients received a median of 19.9 × 108 CAR-GPC3 T cells by a data cutoff date of July 24, 2019. We observed pyrexia, decreased lymphocyte count, and cytokine release syndrome (CRS) in 13, 12, and nine patients, respectively. CRS (grade 1/2) was reversible in eight patients. One patient experienced grade 5 CRS. No patients had grade 3/4 neurotoxicity. The overall survival rates at 3 years, 1 year, and 6 months were 10.5%, 42.0%, and 50.3%, respectively, according to the Kaplan-Meier method. We confirmed two partial responses. One patient with sustained stable disease was alive after 44.2 months. CAR T-cell expansion tended to be positively associated with tumor response. This report demonstrated the initial safety profile of CAR-GPC3 T-cell therapy. We observed early signs of antitumor activity of CAR-GPC3 T cells in patients with advanced HCC.

A phase Ib clinical trial on intratumoral administration of autologous CD1c (BDCA-1)+ myeloid dendritic cells (myDC) in combination with ipilimumab (IPI) and avelumab (AVE) plus intravenous low-dose nivolumab (NIVO) in patients with advanced solid tumors.

e14012 Background: Intratumoral (IT) myDC play a pivotal role in initiating antitumor immune responses and "re-licensing” of antitumor cytotoxic T-lymphocytes within the tumor microenvironment. IT injection of anti-PD-L1 IgG1 mAb AVE and anti-CTLA-4 IgG1 mAb IPI may reduce the number of regulatory T cells and lyse PD-L1+ tumor cells, thereby releasing tumor antigens that can be captured and processed by IT co-administered CD1c (BDCA-1)+ myDC, reinvigorating the cancer immunity cycle. Methods: Patients (pts) with advanced solid tumors who failed standard therapy were eligible for IT injections of ≥1 non-visceral metastasis with IPI (max total dose of 10 mg) and AVE (max total dose of 40 mg) plus IV NIVO (10 mg) on day 1 followed by IT injection of autologous, non-substantially manipulated CD1c (BDCA-1)+ myDC on day 2. Administration of AVE, IPI, and NIVO was repeated every 14 days thereafter. Primary endpoints were safety and feasibility. Repetitive FNA cytology/IHC of treated lesions was performed. Results: In this ongoing trial, 6 pts (3x melanoma, 1x epithelial ovarian carcinoma, 2x triple negative breast carcinoma) were treated with IT injection of a median of 27,2x106 (range 10-43x106) CD1c (BDCA-1)+ myDC and a median of 5 (range 2-10) study drug administrations. At time of this analysis 3 pts are evaluable for response: an ongoing PR ( > 8 months) was documented in a melanoma pt who previously progressed on PD-1 and CTLA-4 inhibitors. In 2 other melanoma pts regression of the injected metastases coincided with progression of non-injected metastases. Adverse events consisted of transient grade(G)2 local pain at injection site in 2 pts, G1 pruritus in 2 pts, G2 pneumonitis in 1 pt, G1 rash in 1 pt, and pruritus and redness of the skin overlaying the injected lesion in 1 pt. Analysis of cytology/IHC results is ongoing. Conclusions: IT injection of autologous CD1c (BDCA-1)+ myDC with IT co-injection of AVE and IPI plus IV low-dose NIVO is feasible and tolerable and resulted in encouraging early signs of anti-tumor activity in injected as well as non-injected lesions. Clinical trial information: NCT03707808.

Phase 1 dose escalation study of XMT-1536, a novel NaPi2b-targeting antibody-drug conjugate (ADC), in patients (pts) with solid tumors likely to express NaPi2b.

3010 Background: XMT-1536 is a Dolaflexin ADC targeting the sodium-phosphate cotransporter NaPi2b, expressed in ovarian, non-squamous lung, papillary thyroid, endometrial, papillary renal and salivary duct cancers. Methods: In this ongoing Phase 1 study, pts with solid tumors likely to express NaPi2b, who progressed on standard therapy, are treated with intravenous XMT-1536 using a 3+3 design with a modified Fibonacci escalation. NaPi2b expression by IHC is being examined retrospectively in archived tumors. Primary objectives in dose escalation are safety and tolerability and determination of maximum tolerated dose (MTD) and recommended Phase 2 dose (RP2D). (ClinicalTrials.gov NCT03319628). Results: As of Jan. 28, 2019, 36 pts (22 ovarian, 7 endometrial, 4 NSCLC, 3 other) have received treatment with XMT-1536. Treatment was initially given every 3 weeks (q3w); 20 pts were treated in dose cohorts from 3 to 40 mg/m2. There was one DLT of reversible AST elevation at 40 mg/m2. The dosing interval was then changed to every 4 weeks (q4w), and dose escalation was restarted at 20 mg/m2. There was one DLT of reversible AST elevation at 30 mg/m2 on the q4w schedule. Further followup and dose escalation are ongoing. The most common (≥10% of patients) treatment-related adverse events (TRAEs) have been nausea, fatigue, headache, increased AST, anorexia, increased alkaline phosphatase, fever, increased GGT, myalgia, and vomiting. Grade 3 TRAEs were reversible AST increases in 3 patients and increased GGT, decreased lymphocytes, and systolic congestive heart failure in 1 patient each. Treatment-related serious AEs of fever and systolic congestive heart failure occurred in 1 patient each. Among patients dosed at 20 mg/m2 or higher who had restaging scans (n=20), there were 2 PR, in ovarian cancer pts at 30 mg/m2 q3w and 20 mg/m2 q4w, and 11 SD, with disease control maintained for up to 24 weeks. Patient-level results for NaPi2b expression will be presented. The systemic exposure of total payload showed approximately dose-proportional increase. Plasma concentration of free drug payload and its active metabolite were low. Conclusions: XMT-1536 has been well-tolerated up to the 30 mg/m2 dose level with early signs of anti-tumor activity. Dose escalation continues in pts with advanced solid tumors likely to express NaPi2b. Clinical trial information: NCT03319628.

P1.07-002 G1T28, a Cyclin Dependent Kinase 4/6 Inhibitor, in Combination with Topotecan for Previously Treated Small Cell Lung Cancer: Preliminary Results

Chemotherapy-induced bone marrow and immune system toxicity causes significant acute and long-term consequences. G1T28 is a potent and selective CDK4/6 inhibitor (CDK4/6i) in development to reduce chemotherapy-induced myelosuppression and preserve immune system function in small cell lung cancer (SCLC) patients. Hematopoietic stem and progenitor cells (HSPC) are dependent upon CDK4/6 for proliferation, and preclinical models demonstrated that transient G1T28-induced G1 cell cycle arrest renders them resistant to chemotherapy cytotoxicity, allowing faster hematopoietic recovery, preservation of long-term stem cell and immune system function, and enhancement of chemotherapy anti-tumor activity. Objectives of this ongoing multicenter Phase 1b/2a study are to assess the dose limiting toxicities (DLTs), safety, hematological profile, PK, and anti-tumor activity of G1T28 in combination with topotecan (NCT02514447). The study consists of a limited open-label, dose-finding portion (Part 1; up to 40 patients), and an open-label, single-arm expansion portion (Part 2; 28 patients). Eligible patients had histologically/cytologically confirmed SCLC, adequate organ function, ECOG performance status 0-2, 1-2 prior lines of chemotherapy, and no symptomatic brain metastases. G1T28, at a starting dose of 200 mg/m2 (derived from the Phase 1a healthy volunteer study and expected to maintain HSPC G1 arrest beyond topotecan exposure), was administered IV prior to IV topotecan on days 1-5 every 21-days. 21 patients (median age 68, 5 females, 20 white and 1 African-American) have been enrolled across 5 cohorts. DLTs due to Grade 3/4 myelotoxicity occurred in the first two cohorts and were associated with supra-therapeutic topotecan exposures due to decreased topotecan clearance by G1T28. Reducing the topotecan dose achieved exposures in the therapeutic range and was well tolerated. No episodes of febrile neutropenia or bleeding have occurred to date. For the 17 evaluable patients, there were 5 PR, 8 SD, and 4 PD. In the 6 platinum refractory patients there were 1 PR, 3 SD, and 2 PD. G1T28, a novel CDK4/6i, combined with topotecan for previously treated SCLC patients has been well tolerated, without any episodes of febrile neutropenia or bleeding. There are encouraging early signs of anti-tumor activity, with a response rate of 29% overall (36%, 4/11 in sensitive and 17%, 1/6 in refractory) and a clinical benefit rate (CR+PR+SD) of 76% overall (82%, 9/11 in sensitive and 67%, 4/6 in refractory). This novel approach, allowing the administration of chemotherapy with preservation of hematopoietic function and cellular immunity, could potentially improve treatment outcomes of patients with CDK4/6-independent tumors. Updated data will be presented.

Ginkgo biloba extract in combination with sorafenib is clinically safe and tolerable in advanced hepatocellular carcinoma patients

BackgroundSorafenib is the only therapy shown to improve overall survival in advanced hepatocellular carcinoma (HCC). However, the clinical efficacy of sorafenib is limited. Combination therapy targeting multiple signaling pathways may improve outcomes. Ginkgo biloba extract (GBE) has exhibited antitumor activity in multiple human cancers. Hypothesis/purposeThis study was designed to evaluate the tolerability and effectiveness of GBE combined with sorafenib in patients with advanced HCC. Study designPatients with advanced HCC were treated with increasing doses of GBE in combination with sorafenib. MethodsWe first determined the maximum tolerated dose (MTD) of GBE, then the patients were treated with GBE at the MTD to evaluate its safety and efficacy. 27 patients were enrolled in the first part of our study and treated with sorafenib 400mg twice daily (BID) and increasing doses (cohort 1: 60mg, cohort 2: 120mg, cohort 3: 240mg, cohort 4: 360mg) of GBE once daily (QD). An additional group of 32 new patients next to the 27 described before were accrued for the second part of our study, and all these 32 patients were eligible for the evaluation of toxicity and efficacy. ResultsNo patient in cohort 1 and 2 experienced a dose-limiting toxicity (DLT). One of the ten patients in cohort 3 experienced a DLT. DLT occurred in two of the three initial patients in cohort 4. Cohort 3 (GBE 240mg QD plus sorafenib 400mg BID) was considered to be the MTD. Three patients had a partial response, 21 had stable disease, and 8 had progressive disease. The median times to progression and overall survival were 2.5 and 11.6 months, respectively. Compared with previous study, the toxicities of the combination therapy were similar with those observed in sorafenib monotherapy, GBE in combination with sorafenib slightly improved OS. ConclusionsThe combination of GBE (240mg QD) and standard dose sorafenib (400mg BID) is safe and tolerable among patients with advanced HCC. Early signs of antitumor activity may warrant further development of this combination.