Dose-limiting Toxicity Evaluation Period Research Articles

Abstract CT084: A phase 1 study of LY4101174 (ETx-22), an antibody-drug conjugate targeting nectin-4, in patients with advanced or metastatic urothelial cancer and other solid tumors (trial in progress)

Abstract Background: Nectin-4 is a cell adhesion molecule expressed in multiple tumor types.1 Enfortumab vedotin (EV), an antibody-drug conjugate (ADC) comprising a fully humanized nectin-4 antibody conjugated to the microtubule inhibitor, monomethyl auristatin E (MMAE), is approved for the treatment of advanced urothelial cancer (UC). However, skin toxicity, peripheral neuropathy, and hyperglycemia are clinically significant toxicities with EV. LY4101174 (ETx-22) is a next-generation nectin-4 targeting ADC comprising a humanized IgG1 Fc-silent monoclonal antibody linked to the topoisomerase I inhibitor, exatecan, via a maleimide-ß-glucuronide poly-sarcosine linker with improved stability and a homogeneous drug-antibody ratio (DAR) of 8. Preclinically, LY4101174 has demonstrated robust in vivo efficacy in tumor models across a range of nectin-4 expression levels and in the nectin-4-MMAE ADC treated resistant tumor model.2 Methods: LOXO-ENC-23001 is a global, open-label, multi-center, first-in-human phase 1 study of LY4101174 in patients (pts) with advanced or metastatic solid tumors known to express nectin-4. LY4101174 will be administered intravenously and evaluated initially on either every 2 weeks or 3 weeks schedule. Eligible pts (≥18 years) must have good performance status (ECOG PS 0-1) with metastatic UC, head and neck squamous cell carcinoma, esophageal, pancreatic, prostate, non-small cell lung, cervical, ovarian, or triple-negative breast cancer, and must have received or not be a candidate for available standard therapies. The study will be conducted in 2 phases: phase 1a dose escalation/dose optimization and phase 1b dose expansion. Dose escalation will utilize a Bayesian optimal interval design. Additional pts will be allowed to backfill to previously cleared dose levels that demonstrate therapeutically relevant exposures or direct evidence of clinical activity. The dose-limiting toxicity evaluation period will be 21 or 28 days based on dosing schedules. Phase 1b dose expansion cohorts will enroll pts with selected tumor types: mUC with no prior EV treatment (cohort B1), mUC with prior EV treatment (cohort B2), and other selected non-UC tumors (cohort C). Primary objectives are to determine the recommended phase 2 dose (RP2D) and assess the safety of LY4101174. Key secondary objectives are to evaluate the pharmacokinetic profile, immunogenicity, and antitumor activity of LY4101174 per RECIST v1.1. Nectin-4 expression and other biomarker data will be generated and correlated with clinical activity. 1Challita-Eid PM et al. 2016 Cancer Res 76(10):3003-13. 2Azim H et al. 2023 Mol Cancer Ther 22(12_Suppl):B128. Citation Format: Jonathan Rosenberg, Renaud Sabatier, Armelle Viceneux, Thibault de La Motte Rouge, Stephane Champiat, Loic Lebellec, Philippe Barthélémy, Guru Sonpavde, Xin Gao, Scot Niglio, Tian Zhang, Craig Gedye, Matthew Galsky, Matthew Milowsky, Melissa Reimers, Andrew Weickhardt, Enrique Grande, Daniel E. Castellano, Mehmet Bilen, Amita Patnaik, Robert Zerbib, Minna Balbas, Xiaojian Xu, Kaitlyn Aptaker, Arjun V. Balar, Ahmad H. Awada. A phase 1 study of LY4101174 (ETx-22), an antibody-drug conjugate targeting nectin-4, in patients with advanced or metastatic urothelial cancer and other solid tumors (trial in progress) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT084.

Abstract CT100: Safety and efficacy of AZD8853, an anti-growth and differentiation factor 15 (GDF15) antibody, in patients (pts) with advanced/metastatic solid tumors: First-in-human study

Abstract Background: GDF15 is overexpressed in solid tumors, with immunosuppressive effects on dendritic cells (DCs), T cells and myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment. AZD8853 is an IgG1 monoclonal antibody that neutralizes GDF15. This Phase 1/2a, open-label study assessed AZD8853 monotherapy in previously treated advanced/metastatic non-small-cell lung cancer, microsatellite-stable colorectal cancer (MSS-CRC) and urothelial carcinoma (UC) (NCT05397171). Methods: Eligible pts were ≥18 years old with ≥1 measurable lesion per RECIST v1.1 and ECOG PS 0/1. AZD8853 was given IV Q3W until disease progression, unacceptable toxicity or consent withdrawal. The primary objective was safety including dose-limiting toxicities (DLTs). Secondary objectives included efficacy, pharmacokinetics (PK) and pharmacodynamics (PD [free serum GDF15]). Exploratory objectives included peripheral immune PD. Results: During dose escalation, 16 pts (15 MSS-CRC, 1 UC) received AZD8853 (300 mg, n=3; 1000 mg, n=6; 3000 mg, n=7). By June 6, 2023, all pts discontinued treatment and the study. Thirteen pts (81.3%) had treatment-emergent adverse events (TEAEs; Table); the most common were diarrhea (31.3%), abdominal pain (31.3%) and decreased appetite (25%). Eight pts (50%) had Grade ≥3 TEAEs and 6 (37.5%) had serious TEAEs; none treatment-related. There were no DLTs. No pts had responses by RECIST; 5 (31.3%) had stable disease and 11 (68.8%) had disease progression as best response. AZD8853 PK was linear with a half-life of 5-10 days, supporting Q3W dosing. GDF15 suppression was transient. There was no evidence of ctDNA clearance or a dose-dependent change in peripheral immune cells including CD8+ and CD4+ T cells, DCs and MDSCs. Conclusions: AZD8853 was well tolerated. No objective responses or PD effects were seen and GDF15 suppression was not sustained, therefore no further development is planned. TABLE 1. NAND Table. AZD8853 safety AZD8853 300 mg 1000 mg 3000 mg Total Safety, n (%) N=3 N=6 N=7 N=16 TEAEs 3 (100) 4 (66.7) 6 (85.7) 13 (81.3) Grade ≥3 TEAEs 1 (33.3) 3 (50.0) 4 (57.1) 8 (50.0) TRAEs 1 (33.3) 0 2 (28.6) 3 (18.8) Grade ≥3 TRAEs 0 0 0 0 Serious TEAEs 1 (33.3) 3 (50.0) 2 (28.6) 6 (37.5) TEAEs leading to discontinuation of AZD8853 0 1 (16.7)* 0 1 (6.3) TEAEs leading to death 0 1 (16.7)* 0 1 (6.3) DLTs, n (%) N=3 N=6 N=6 † N=15 DLTs 0 0 0 0 *Death due to serious AE of cardiac arrest, unrelated to AZD8853; pt had a history of coronary artery disease, coronary stenting, and pulmonary embolism.†One pt discontinued due to clinical progression prior to completing the DLT evaluation period and was not included in the DLT-evaluable set. DLTs, dose-limiting toxicities; TEAEs, treatment-emergent adverse events, TRAEs, treatment-related adverse events Citation Format: Benedito A. Carneiro, Olumide Gbolahan, Albiruni Abdul Razak, John F. Hilton, Arthur Lambert, John Hood, Michael Pluta, Veronique Bragulat, Elhan Sanai, Rakesh Kumar, Duncan Jodrell, Patricia LoRusso. Safety and efficacy of AZD8853, an anti-growth and differentiation factor 15 (GDF15) antibody, in patients (pts) with advanced/metastatic solid tumors: First-in-human study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT100.

Phase 1b Trial of Irak 1/4 Inhibition for Low-Risk Myelodysplastic Syndrome Refractory/Resistant to Prior Therapies: A Trial in Progress

Background and Significance: Chronic stimulation of both the interleukin-1 receptor (IL-1R) and toll-like receptors (TLRs) in myeloid progenitors is thought to promote a proinflammatory environment in the bone marrow that causes persistent cytopenia in patients with low-risk myelodysplastic syndrome (LR-MDS). The serine/threonine kinases IRAK1 and IRAK4 are critical for the signaling downstream of IL-1R and most TLRs that promotes production of proinflammatory cytokines and NLRP3 inflammasome-driven pyroptosis, leading to bone marrow inflammation and cell death. Therefore, inhibition of IRAK1/4 is a potential target for the treatment of LR-MDS by decreasing inflammation and cell death within the bone marrow, allowing for restoration of hematopoiesis. R289 is a prodrug that is converted to the active drug R835 in the gastrointestinal (GI) tract. R835 is a potent and selective inhibitor of IRAK1 and IRAK4 kinases that inhibits TLR and IL-1R-dependent proinflammatory cytokine production in multiple cell types. In vivo, R835 blocks TLR4 and IL-1R-dependent systemic cytokine release in mice. The safety and pharmacokinetic properties of R289/R835 were evaluated in a phase 1 study in healthy volunteers (Study C-906289-001). R289 was well tolerated with no serious or severe adverse events (AEs) reported. Most AEs were mild and transient; the most common AEs (mild/moderate) were headache and GI disturbance. Overall, the phase 1 trial results supported the further study of R289. An open-label phase 1b study to determine the tolerability and preliminary efficacy of R289 for patients with LR-MDS refractory to prior therapies is currently recruiting patients. Study Design and Methods: The R289 phase 1b study (NCT05308264) is an open label, single arm, multi-center study, which includes a dose escalation phase (up to 12 patients) and a dose expansion phase (up to 10 patients). Inclusion criteria for both phases will include patients ≥18 years with a definitive diagnosis of low-risk MDS (International Prognostic Scoring System-R ≤3.5) and ≤5% bone marrow myeloblasts. Patients must be relapsed or refractory/resistant or intolerant to prior MDS therapies. Exclusion criteria include prior MDS treatment(s) within 4 weeks of study treatment, clinically significant anemia (from iron deficiency, hemolysis, or GI bleeding), and chronic myelomonocytic leukemia. Dose Escalation Phase: A 3+3 dose escalation design will be used to determine the maximum tolerated dose (MTD). An initial R289 dose of 250 mg qd, will be given orally, with or without food, progressing to 500 mg qd with dose limiting toxicity (DLT) assessed at both doses. The DLT evaluation period will be 28 days. After completion, patients not experiencing DLTs may remain at their respective dose levels as long as they demonstrate continued clinical benefit without toxicity. Dose Expansion Phase: Up to 10 additional patients with LR-MDS will be enrolled, with R289 administered to all patients at a dose not exceeding the MTD determined in the dose escalation phase. The primary endpoint of the study is safety and tolerability of R289, assessed by incidence of AEs, discontinuation/interruption of R289 due to AEs, and incidence of DLTs. Secondary endpoints include preliminary efficacy, assessed by red blood cell transfusion independence by Week 24 (% achieving ≥50% reduction in transfusions), and pharmacokinetics of R289. Change from baseline in plasma biomarkers, including C-reactive protein and TNFα, and bone marrow biomarkers will be assessed. Statistical analyses will be primarily descriptive. Tabulations will be produced for disposition, demographics, disease characteristics, safety, pharmacokinetics, pharmacodynamics, and clinical activity. For analyses of clinical activity, such as proportion of patients with RBC transfusion independence, complete responder rate, overall response rate, and proportion of subjects with hematologic improvements, the summary will be produced separately for the dose escalation phase and dose expansion phase. For the dose escalation phase, data will be summarized by dose level and overall. The trial is currently recruiting at 9 US sites. The study has enrolled 7 patients in the dose escalation phase.

A Phase I, Single-Arm, Open Label, Dose Escalation, Multicenter Study of Off-the-Shelf Natural Killer (NK) Cells (SAR445419) in Patients with Relapsed/Refractory Acute Myeloid Leukemia (R/R AML)

Background and Significance: SAR445419 (SAR'419) is an allogeneic, off-the-shelf, donor-derived, natural killer (NK) cell investigational immunotherapy. NK cells in SAR'419 are expanded ex vivo using PM21 particles expressing membrane-bound interleukin-21 and 4-1BB ligand from the plasma membranes of feeder cells (Ciurea et al, Leukemia, 2022). Ex vivo, PM21 expansion allows for large numbers of hyperactive NK cells to be generated and administered, thereby increasing therapeutic potential to patients. It is hypothesized that mature, fully functional NK cells expanded ex vivo will have superior anti-tumor activity, favorable safety profile, and can induce remissions, enabling patients to receive curative allogeneic hematopoietic stem cell transplantation (HSCT), thereby improving outcomes in patients with R/R AML. Two phase 1/2 dose-escalation and expansion studies (NCT01787474, NCT02809092) of ex vivo expanded haploidentical donor NK cells infused as 6 doses over a course of 2 weeks, after fludarabine and cytarabine chemotherapy, demonstrated this approach to be feasible with favorable safety profile in patients with R/R AML. This study aims to determine the candidate dose(s), evaluate safety, tolerability, and preliminary anti-tumor activity of SAR'419 administered after fludarabine and cytarabine chemotherapy for adult patients with R/R AML. Study Design and Methods: This is a phase 1, single-arm, dose escalation study (NCT05712278). The primary objective is to determine the candidate dose(s) based on the evaluation of dose-limiting toxicities (DLTs). The DLT evaluation period is from start of chemotherapy (Day -6) until 28 days after the first administration of SAR'419, starting at the lowest dose. Eligible patients will be administered fludarabine, 30 mg/m 2/day and cytarabine, 2 g/m 2/day (Day -6 to Day -2) for 5 days followed by 6 doses of SAR'419 (intravenous) given thrice weekly over 2 weeks beginning on Day 1. Approximately 12 DLT-evaluable patients will be enrolled. The treatment period will start from the first administration of chemotherapy (Day -6) until end of treatment on Day 56, and subsequently patients will have follow-up visits every 2 months. Dose escalation will be guided by the modified toxicity probability interval 2 design. Key secondary objectives include characterization of overall safety, tolerability, HSCT rate, impact of SAR'419 on infection, and preliminary anti-leukemic activity of SAR'419 (as per international working group criteria). Biomarkers in whole blood (including serum and plasma) and bone marrow (aspirates-liquid, and biopsy-solid) will be evaluated to assess the impact of SAR'419 treatment. Key inclusion criteria are adult participants with confirmed diagnosis of R/R AML according to World Health Organization classification, including participants with relapsed AML in the bone marrow after allogeneic HSCT (including those who have received donor lymphocyte infusions); with or without concomitant or with isolated central nervous system or extramedullary disease who have received at least 1 prior line of therapy for AML. Key exclusion criteria are participants with a second primary malignancy requiring active therapy (adjuvant hormonal therapy is allowed); with known acquired immunodeficiency syndrome or human immunodeficiency virus disease requiring antiretroviral treatment or having active hepatitis B or C infection, or symptomatic severe acute respiratory syndrome coronavirus 2 infection; and who are receiving >10 mg/day of oral prednisone or equivalent. In the safety analyses, all DLT modeling will be performed on the DLT-evaluable population or those who experienced a DLT. All other safety analyses will be performed on the safety population using descriptive statistics. This study is actively recruiting at this time and is being conducted in the United States.

CTIM-14. PHASE 1 SAFETY LEAD-IN AND RANDOMIZED OPEN-LABEL PERIOPERATIVE STUDY OF VORASIDENIB COMBINED WITH PEMBROLIZUMAB IN RECURRENT OR PROGRESSIVE ENHANCING IDH1-MUTANT ASTROCYTOMAS: SAFETY LEAD-IN RESULTS

Abstract Isocitrate dehydrogenase 1 mutations (mIDH1) occur in ~80% of grade 2/3 gliomas. Vorasidenib (VOR), an oral, brain-penetrant, dual inhibitor of mIDH1/2 enzymes, is an investigational treatment for mIDH gliomas. A neoadjuvant perioperative study in grade 2/3 mIDH gliomas suggested VOR renders the tumor immune microenvironment amenable to immune checkpoint blockade. This study (NCT05484622) evaluates safety/tolerability of VOR plus pembrolizumab to determine the recommended combination dose (RCD) (safety lead-in phase), and CD3+ T-cell infiltration in tumors following preoperative treatment (perioperative phase). Seven patients with recurrent or progressive enhancing grade 2/3 astrocytoma with an IDH1-R132H mutation were dosed in the safety lead-in phase: median age 39 (range, 34–60) years, 3 (43%) female, 6 (86%) grade 3 at screening. Patients received VOR 40 mg orally once daily (QD) plus pembrolizumab 200 mg intravenously once every 3 weeks (Q3W). As of April 29, 2023, patients received a median of 2 (range, 2–5) cycles with six (86%) ongoing; one (14%) discontinued due to disease progression. No dose-limiting toxicities (DLTs), adverse events (AEs) leading to study drug discontinuation, or AEs of special interest (AESI, elevated liver transaminases) were reported during the DLT evaluation period. Six (86%) patients experienced a treatment-related AE, none of which were grade ≥ 3. One (14%) patient experienced a serious, related AE of dysphasia (leading to VOR and pembrolizumab interruption) that subsequently resolved; both drugs were resumed. After the data cut-off, one patient (14%) experienced a grade 2 AESI. Based on safety review committee evaluation, VOR 40 mg QD + pembrolizumab 200 mg Q3W was confirmed as the RCD for the recently initiated perioperative phase. In this phase, ~60 patients will be randomized 1:1:1 to the RCD, VOR 40 mg QD alone, or no treatment prior to surgery. All patients can receive the RCD post-surgery. Funding: Servier and Merck & Co., Inc.

Results of a Phase 1 Trial Testing the Novel Combination Therapy of Venetoclax and Ruxolitinib in Relapsed/Refractory Acute Myeloid Leukemia Patients

Introduction : A functional small molecule screen on a large cohort of primary AML patient samples revealed that the combination of Ruxolitinib (Rux) and Venetoclax (Ven) exhibited ex vivo efficacy and synergy in both newly diagnosed and R/R AML. This observation motivated a Phase I multi-center trial to evaluate Rux+Ven in R/R AML, for which we now report complete toxicity and efficacy data for 30 subjects. Methods: This study was designed to identify a maximum tolerated or recommended Phase II dose (RP2D) and evaluate the overall safety and preliminary efficacy of Rux+Ven therapy. Eligible subjects were ≥18 years old with R/R AML. There was no restriction on the number of previous therapies or prior exposure to Ven or Rux. We included subjects with prior allogeneic transplant if GVHD was controlled and prior MDS (≥75 years old or having poor cardiac or kidney function) who progressed on a hypomethylating agent (HMA) but had no primary AML therapy. In cohorts of 3 to 4, subjects were assigned to receive Rux+Ven at 1 of 6 dose levels according to the “keyboard” Bayesian toxicity probability interval design applied to a target dose-limiting toxicity (DLT) rate of 30%. DLTs were defined as non-disease-related, Grade ≥3 non-hematologic toxicities, with exceptions for nausea, vomiting, infections, febrile neutropenia episodes, and electrolyte abnormalities that resolved within 48 hours. Hematologic DLT was specified as Grade 4 neutropenia after 42 days in the absence of disease. The DLT evaluation period covered the first cycle. Subjects could continue study therapy after two 28-day cycles if they had a response (ie, CR/CRi or MLFS) or were otherwise deriving clinical benefit. Results : This Phase 1 study has completed enrollment (n=30), with all but one patient off-treatment as of June 2023. Baseline patient characteristics are summarized in Table 1. Median age was 69 (range 29-84), 40% of subjects had ≥3 prior therapies, and 43% had prior Ven. At enrollment, 30% had prior MDS, 24% had mutated TP53 (of 25 patients with available data), and 47% had CD56+ blasts. The numbers of patients treated by dose level (DL) were: 3 on DL0 (200 mg qd Ven; 10 mg bid Rux), 4 on DL1 (400 mg qd Ven; 10 mg bid Rux), 3 on DL2 (400 mg qd Ven; 20 mg bid Rux), and 20 on DL3 (400 mg qd Ven; 30 mg bid Rux), the highest dose level of the study. Per prescribing guidelines, the cycle 1 Rux doses of 15 subjects and Ven doses of 20 subjects were reduced because of a concomitant CYP3A inhibitor. The regimen was well-tolerated. As no DLTs were observed, DL3 is the RP2D. The median (interquartile range) duration of therapy was 55 (36-93) days. The most common grade ≥3 hematologic AEs, regardless of attribution, were thrombocytopenia (50%; which was 30% at study enrollment), anemia (40%; 40% at enrollment), neutropenia (37%; 10% at enrollment), febrile neutropenia (33%), and leukopenia (33%; 7% at enrollment). Six subjects had a Grade 5 AE: 4 were unrelated to study drug (2 death NOS, 1 lung infection, 1 respiratory failure) and 2 were potentially related to Ven (1 sepsis, 1 neutropenic pneumonia). Over the first 2 cycles of study therapy, the Clinical Benefit Rate (CBR; defined as the proportion of subjects obtaining at least stable disease) was 63% (95% CI: 44%-80%). Morphologic leukemia-free state (MLFS) was achieved in 20% (95% CI: 8%-39%) and Composite Complete Remission in 10% (95% CI: 2%-27%). Median overall survival (OS) was 3.7 months (95% CI: 2.3-6.5), with 23% (95% CI: 10%-39%) alive 1 year after commencing Rux+Ven. Two participants were exceptional responders: the first achieving MLFS and receiving 16 cycles of study therapy and the second having a complete remission and remaining on-treatment after 31 cycles. Pre-Rux+Ven CD56 expression on blasts correlated with worse response (all 6 ≥MLFS patients were CD56-; Fig 1) and overall survival (HR=2.37, p=0.044; Table 1). Correlative studies such as ex vivo drug assessment, genomic analysis, CyTOF, and single-cell imaging will be presented to enhance this finding. Conclusion: The novel, all-oral combination of Rux+Ven in R/R AML patients was well-tolerated with no DLTs and an encouraging 63% CBR over cycles 1-2. Negative CD56 was a biomarker of response, although additional work is required to determine if this is a broad association with Ven-based therapies or unique to the Rux+Ven combination. The tolerable toxicity profile of Rux+Ven makes it a promising combination to test with HMAs in high-risk AML patients.

OS09.2.A REGORAFENIB IN COMBINATION WITH TEMOZOLOMIDE WITH OR WITHOUT RADIOTHERAPY IN PATIENTS WITH NEWLY DIAGNOSED MGMT-METHYLATED, IDH WILDTYPE GLIOBLASTOMA: A PHASE I DOSE-FINDING STUDY (REGOMA-2, EUDRA CT N° 2021-001604-15)

Abstract BACKGROUND Glioblastoma (GBM) is associated with the activation of multiple signaling pathways, including the receptor tyrosine kinases, VEGFR, FGFR and PDGFR. The potential response to anti-angiogenic agents makes GBM an attractive target for regorafenib (REG). Antitumor activity of REG in recurrent GBM patients was shown in the phase II REGOMA trial. Interestingly, in “in vivo” studies, beneficial effects were observed with the combination of REG and temozolomide (TMZ) in subcutaneous xenografts. MATERIAL AND METHODS This phase I open-label multicentric study in progress is evaluating the addition of REG to standard of care treatment with TMZ as adjuvant therapy (cohort A), and in combination with TMZ + radiotherapy (RT) as concomitant therapy (cohort B), in newly diagnosed MGMT-methylated, IDH wildtype GBM patients. Primary objectives are: to determine the safety and tolerability of REG and to establish the maximum tolerated dose (MTD) of REG in these two cohorts. Secondary objectives are: the assessment of pharmacokinetics of REG, TMZ, and possible pharmacokinetic interactions between TMZ and REG in cohort A; the assessment of preliminary antitumor activity; the evaluation of quality of life during the treatment. The dose escalation is being explored according to a “3 + 3” design, starting from cohort A and following 3 dose levels of REG [80 mg, 120 mg and 160 mg]. After finding the MTD in cohort A, the cohort B dose escalation will start, exploring escalating oral doses of REG in combination with concomitant TMZ + RT (60 Gy/30 fractions). In the adjuvant phase of cohort B, REG will be given with TMZ at MTD shown in the prior adjuvant phase dose escalation.The DLT (dose-limiting toxicity) evaluation period will be two cycles from the start of cycle 1 of adjuvant phase (in cohort A) and from day 1 to the last day of the concomitant phase (in cohort B). Recruitment started in May 2022; Level 1 in cohort A (3 patients) has been completed without DLT. Approximately 36 subjects will be enrolled.

Phase 1b clinical study of IRAK 1/4 inhibition for low-risk myelodysplastic syndromes refractory/resistant to prior therapies.

TPS7085 Background: Chronic stimulation of both interleukin-1 receptor (IL-1R) and toll-like receptors (TLRs) in myeloid progenitors is thought to cause a bone marrow proinflammatory environment responsible for persistent cytopenia in patients with low-risk (LR)-MDS. IRAK1 and IRAK4 are serine/threonine kinases that are critical for the downstream signaling of IL-1R and most TLRs resulting in the production of proinflammatory cytokines and NLRP3 inflammasome-driven pyroptosis leading to bone marrow inflammation and cell death. Thus, IRAK1/4 inhibition is a potential target for the treatment of LR-MDS by decreasing inflammation and cell death within the bone marrow allowing the restoration of hematopoiesis. R289 is a prodrug that is converted to the active drug R835 in the gastrointestinal (GI) tract. R835 is a potent and selective inhibitor of IRAK1 and IRAK4 kinases and inhibits TLR and IL-1R-dependent proinflammatory cytokine production in multiple cell types. In vivo, R835 blocks TLR4 and IL-1R-dependent systemic cytokine release in mice. The safety and pharmacokinetic properties of R289/R835 were evaluated in a phase 1 healthy volunteer study (Study C-906289-001). R289 was well tolerated with no serious or severe adverse events (AEs) reported. Most AEs were mild and transient; the most common AEs (mild/moderate) were headache and GI disturbance. Overall, the trial supported the advancement of R289 into further studies. An open-label Phase 1b study to determine the tolerability and preliminary efficacy of R289 for patients with LR-MDS refractory to prior therapies is currently enrolling patients. Methods: The current study (NCT05308264) includes a dose escalation phase (up to 12 patients) and a dose expansion phase (up to 10 patients). Inclusion criteria for both phases will include patients ≥18 years with a definitive diagnosis of LR-MDS. Exclusion criteria will include prior treatment for MDS that concluded <4 weeks prior to study treatment. Dose Escalation Phase: Dose escalation will utilize a 3+3 design to determine the maximum tolerated dose (MTD). R289 tablets can be taken orally with or without food. Dose limiting toxicity (DLT) will be assessed at each dose level. The DLT evaluation period will be 28 days. After completion of the DLT evaluation period, patients who do not experience DLTs may remain on treatment at their respective dose level if they continue to demonstrate clinical benefit without toxicity. Dose Expansion Phase: Up to 10 additional patients with LR-MDS will be enrolled; the primary endpoint of the study will be the safety and tolerability of R289. The secondary endpoints will include an assessment of preliminary efficacy and characterization of the pharmacokinetics of R289. R289 will be administered to all patients at a dose not to exceed the MTD determined in the Dose Escalation Phase. The trial is currently recruiting at 8 US sites. Clinical trial information: NCT05308264 .

Safety and efficacy of inetetamab in combination with pyrotinib in HER2 mutant patients with non-small cell lung cancer (NSCLC): An open-label, phase Ib trial.

9105 Background: Currently, limited targeted therapies are available for HER2 mutant NSCLC patients. Previous studies have shown the antitumor activity of pyrotinib in advanced NSCLC patients with HER2 mutations. Inetetamab is a recombinant humanized anti-HER2 monoclonal antibody. Whether inetetamab combined with pyrotinib could show manageable safety and more active antitumor activity remains unknown. This study was designed to evaluate the safety and efficacy of inetetamab in combination with pyrotinib in HER2 mutant patients with advanced NSCLC. Methods: This study was an open-label, phase Ib study. The HER2 mutant patients with locally advanced or metastatic NSCLC were assigned to receive inetetamab combined with pyrotinib. The study consisted of dose-escalation part and dose-expansion part. During dose-escalation period, the parallel "3+3" dose-escalation design was used to determine the dose-limiting toxicity (DLT). Inetetamab was administered every 3 weeks (8 mg/kg loading dose for cycle 1, followed by 6 mg/kg in subsequent cycles) with pyrotinib (dose-escalation part, 240mg QD, 320mg QD; dose-expansion part, 320mg QD). Primary endpoint of the study was DLT dosage and safety. The DLT was assessed during the 21-day DLT evaluation period after the first dose. Secondary endpoints included objective response rate (ORR), disease control rate (DCR), progression free survival and overall survival. Results: Between August 6, 2021, and August 25, 2022, 48 patients were enrolled. No DLT occurred during pyrotinib 240mg and 320mg escalation period. Therefore, pyrotinib 320mg was chosen as expansion dose. The most common treatment-related adverse events (TRAEs) were diarrhea (66.7% [2/3] in pyrotinib 240mg group, 95.6% [43/45] in pyrotinib 320mg group), rash (66.7% [2/3] in pyrotinib 240mg group, 22.2% [10/45] in pyrotinib 320mg group) and vomiting (0 in pyrotinib 240mg group, 24.4% [11/45] in pyrotinib 320mg group). TRAEs were generally Grade (G) 1-2. Only 7 patients reported G3 TRAE (1 in pyrotinib 240mg group, 6 in pyrotinib 320mg group). The preliminary efficacy was shown in the table below. The ORR and DCR of group receiving inetetamab with pyrotinib 240mg were 0% and 66.7%, respectively. The ORR and DCR of inetetamab with pyrotinib 320mg group were 36.6% and 85.4% respectively. The relationship between different mutation subtypes or co-mutations and efficacy will be updated during the conference reports. Conclusions: The preliminary data of inetetamab in combination with pyrotinib showed manageable safety and compelling antitumor activity in advanced NSCLC patients harboring HER2 mutations. Clinical trial information: NCT05016544 . [Table: see text]

A phase I, first-in-human study of TAK-164, an antibody–drug conjugate, in patients with advanced gastrointestinal cancers expressing guanylyl cyclase C

PurposeGuanylyl cyclase C (GCC) is highly expressed in several gastrointestinal malignancies and preclinical studies suggest that it is a promising target for antibody-based therapeutics. This phase I trial assessed the safety and tolerability of TAK-164, an investigational, anti-GCC antibody–drug conjugate (NCT03449030).MethodsThirty-one patients with GCC-positive, advanced gastrointestinal cancers received intravenous TAK-164 on day 1 of 21-day cycles. Dose escalation proceeded based on cycle 1 safety data via a Bayesian model.ResultsMedian age was 58 years (range 32–72), 25 patients (80.6%) had colorectal carcinoma, and median number of prior therapies was four. No dose-limiting toxicities (DLTs) were reported during cycle 1 DLT evaluation period. After cycle 2 dosing, 3 patients reported dose-limiting treatment-emergent adverse events (TEAEs): grade 3 pyrexia and grade 5 hepatic failure (0.19 mg/kg), grade 4 hepatic failure and platelet count decreased (0.25 mg/kg), grade 3 nausea, grade 4 platelet and neutrophil count decreased (0.25 mg/kg). The recommended phase II dose (RP2D) was 0.064 mg/kg. Common TAK-164-related TEAEs included platelet count decreased (58.1%), fatigue (38.7%), and anemia (32.3%). There was a dose-dependent increase in TAK-164 exposure over the range, 0.032–0.25 mg/kg. TAK-164 half-life ranged from 63.5 to 159 h. One patient (0.008 mg/kg) with high baseline GCC expression had an unconfirmed partial response.ConclusionsTAK-164 appeared to have a manageable safety profile at 0.064 mg/kg. Hepatic toxicity was identified as a potential risk. The RP2D of 0.064 mg/kg was considered insufficient to derive clinical benefit; there are no plans for further clinical development.Clinical Trial RegistrationNCT03449030.

CTNI-15. REGORAFENIB IN COMBINATION WITH TEMOZOLOMIDE WITH OR WITHOUT RADIOTHERAPY IN PATIENTS WITH NEWLY DIAGNOSED MGMT-METHYLATED, IDH WILDTYPE GLIOBLASTOMA: A PHASE I DOSE-FINDING STUDY (REGOMA-2)

Abstract Glioblastoma (GBM) has activation of multiple signaling pathways in the tumor microenvironment, including the receptor tyrosine kinases, VEGFR, FGFR and PDGFR. The potential response to anti-angiogenic agents makes GBM an attractive target for regorafenib (REG). Antitumor activity of REG in recurrent GBM patients was shown in the REGOMA trial. Interestingly, in “in vivo” studies, beneficial effects were observed with the combination of REG and temozolomide (TMZ) in subcutaneously xenografts. This phase I open-label multicentric study will evaluate the addition of REG to standard of care treatment with TMZ as adjuvant therapy (cohort A), and in combination with TMZ+RT as concomitant therapy (cohort B), in newly diagnosed MGMT-methylated, IDH wildtype GBM patients. Primary objectives are: to determine the safety and tolerability of REG and to establish the maximum tolerated dose (MTD) of REG in those two cohorts. Secondary objectives are: assessment of pharmacokinetics of REG, TMZ and possible pharmacokinetic interactions between TMZ and REG (cohort A); assessment of preliminary antitumor activity; evaluation of quality of life during the treatment. The dose escalation will be explored according to a “3 + 3” design, starting from cohort A and following 3 dose levels of REG [80 mg, 120 mg and 160 mg; level -1 40 mg will be evaluated in case of Dose-Limiting Toxicity (DLT) during REG 80 mg]. After finding the MTD in cohort A, the cohort B dose escalation will start, exploring escalating oral doses of REG in combination with concomitant TMZ+RT (60 Gy/30 fractions); in the adjuvant phase of cohort B, REG will be given (in association to TMZ) at MTD shown in the prior adjuvant phase dose escalation.The DLT evaluation period will be two cycles from the start of cycle 1 of adjuvant or from day 1 to last day of the concomitant phase. Approximately 36 subjects will be enrolled.

Trial in progress update on ENGOT-cx8/GOG-3024/innovaTV 205: Addition of a new cohort with first-line (1L) tisotumab vedotin (TV) + pembrolizumab (pembro) + carboplatin (carbo) ± bevacizumab (bev) in recurrent/metastatic cervical cancer (r/mCC).

TPS5603 Background: Despite the use of platinum-taxane doublets ± bev in eligible patients (pts), overall survival (OS) outcomes for pts with r/mCC remain poor. With the US approval of pembro + chemotherapy ± bev in the 1L setting for r/mCC with ≥1% of programmed death ligand 1–positive cells in the tumor, an unmet need remains for pts who do not meet this threshold and for pts who progress or are intolerant to standard treatment (tx). TV is a tissue factor–directed antibody–drug conjugate that has been granted accelerated approval in the United States for the tx of adults with r/mCC with disease progression on or after chemotherapy. To develop more effective treatments, we investigated TV in combination with agents with known activity in cervical cancer. We conducted a 2-part, multicohort phase 1b/2 trial, ENGOT-cx8/GOG-3024/innovaTV 205 (NCT03786081), to evaluate TV in combination with bev, pembro, or carbo. The phase 1b dose-escalation phase of innovaTV 205 established the recommended phase 2 dose (RP2D) and the feasibility of these doublet combinations (Monk et al, IGCS 2021). Moreover, we recently reported encouraging antitumor activity from the dose-expansion cohort of TV + carbo (1L; confirmed objective response rate [ORR], 55%; median duration of response [DOR], 8.3 mo) and TV + pembro (second-line; confirmed ORR, 38%; median DOR, 13.8 mo) (Vergote et al, ESMO 2021). The current report describes the design of a new, ongoing dose expansion cohort in the innovaTV 205 study to evaluate the combinations of TV, pembro, and carbo ± bev. Methods: A new cohort has been added to the innovaTV 205 study, comprising adult pts with recurrent or stage IVB squamous, adenosquamous, or adenocarcinoma of the cervix with no prior systemic therapy and an Eastern Cooperative Oncology Group score of 0 or 1. Pts will be treated with the RP2D of TV (2.0 mg/kg) + carbo (AUC 5 mg/mL), pembro (200 mg), and bev (15 mg/kg) every 3 weeks or with TV + carbo (AUC 5 mg/mL) and pembro (200 mg). To assess the regimen’s initial tolerability, there will be a dose-limiting toxicity evaluation period that will consist of completion of 1 tx cycle of 21 days for 6 pts enrolled to receive the quadruplet combination. The primary endpoint of this dose expansion phase is confirmed ORR per RECIST v1.1; secondary endpoints include DOR, time to response, progression-free survival, OS, and safety. Enrollment is ongoing in the United States and Europe, with additional sites planned globally. Clinical trial information: NCT03786081.

NCI 9938: Phase I clinical trial of ATR inhibitor berzosertib (M6620, VX-970) in combination with irinotecan in patients with advanced solid tumors.

3012 Background: Ataxia telangiectasia and Rad3 related (ATR) is activated in response to replication stress from topoisomerase 1 inhibitors. Selective ATR inhibition with berzosertib potentiates the efficacy of irinotecan in colorectal mouse xenograft models. We hypothesized that berzosertib in combination with irinotecan is well tolerated, modulates the DNA damage repair response to irinotecan, and the combination is associated with clinical activity. Methods: This phase I study utilized a modified Storer’s up and down dose escalation design. Dose Levels (DLs) combined berzosertib 60 to 270 mg/m2 with irinotecan 180 mg/m2, every 2 weeks in a 4-week cycle. The primary endpoint was identification of the maximum tolerated dose (MTD) and recommended phase II dose (RP2D). Activity, pharmacokinetics (PK), and pharmacodynamics (PD) were secondary endpoints. The identification of molecular subpopulations sensitized to the combination was exploratory. Results: Between July 2016 and July 2021, 51 patients (pts) enrolled, of whom 50 received treatment. Pts most commonly had colorectal cancer (CRC, 39%), pancreatic cancer (24%), small cell lung cancer (SCLC, 6%) and non-small cell lung cancer (6%). The median number of prior lines of therapy was 4 (range, 2 to 11). In Stage I, 1 of 3 evaluable pts experienced dose-limiting toxicity (DLT) of grade 3 lung infection at DL3 (berzosertib 180 mg/m2 - irinotecan 180 mg/m2), and Stage II was initiated enrolling cohorts of 5 pts. In Stage II, 4 of the first 11 pts treated at DL4 (berzosertib 270 mg/m2 - irinotecan 180 mg/m2) were unable to complete the DLT evaluation period due to clinically significant toxicity not meeting DLT criteria: grade 2 diarrhea (1 pt), grade 3 diarrhea (1 pt), and grade 3 neutrophil decrease (2 pts). The protocol was amended to limit dose escalation beyond DL4. At DL4, 1 of 21 evaluable pts experienced DLT (grade 4 febrile neutropenia). Most common treatment-related grade ≥ 3 toxicities were neutrophil decrease (34%), lymphocyte decrease (30%), WBC decrease (28%), anemia (20%), diarrhea (16%), fatigue (8%) and hypokalemia (8%). 2 partial responses were observed, occurring in pts with pancreatic cancer and ATM alterations: 32% decrease in an ATM E11828/ATM K1109* tumor lasting 15.3 months and 68% decrease in an ATM R3008H/germline ATM R1882* tumor ongoing at 11 months. An additional pt with ATM S214fs*40 mutant colorectal cancer (CRC) experienced a 26% decrease lasting 7.5 months. Conclusions: Berzosertib 270 mg/m2 - irinotecan 180 mg/m2 was declared the RP2D. The combination is associated with manageable side effects and promising disease activity in ATM mutant solid tumors. PK and PD studies are in process. Tumor biopsy studies are planned in a 15 pt dose expansion cohort at DL4, enrolling pts with CRC, pancreatic cancer, SCLC and DNA damage repair deficient tumors. Clinical trial information: NCT02595931.

Safety and efficacy of MIKE-1 in patients with advanced pancreatic cancer: a study protocol for an open-label phase I/II investigator-initiated clinical trial based on a drug repositioning approach that reprograms the tumour stroma

BackgroundCancer-associated fibroblasts (CAFs) are an important component of the tumour microenvironment. Recent studies revealed CAFs are heterogeneous and CAF subset(s) that suppress cancer progression (cancer-restraining CAFs [rCAFs]) must exist in addition to well-characterised cancer-promoting CAFs (pCAFs). However, the identity and specific markers of rCAFs are not yet reported. We recently identified Meflin as a specific marker of rCAFs in pancreatic and colon cancers. Our studies revealed that rCAFs may represent proliferating resident fibroblasts. Interestingly, a lineage tracing experiment showed Meflin-positive rCAFs differentiate into α-smooth muscle actin-positive and Meflin-negative CAFs, which are generally hypothesised as pCAFs, during cancer progression. Using a pharmacological approach, we identified AM80, a synthetic unnatural retinoid, as a reagent that effectively converts Meflin-negative pCAFs to Meflin-positive rCAFs. We aimed to investigate the efficacy of a combination of AM80 and gemcitabine (GEM) and nab-paclitaxel (nab-PTX) in patients with advanced pancreatic cancer.MethodsThe phase I part is a 3 + 3 design, open-label, and dose-finding study. The dose-limiting toxicity (DLT) of these combination therapies would be evaluated for 4 weeks. After the DLT evaluation period, if no disease progression is noted based on the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 or if the patient has no intolerable toxicity, administration of AM80 with GEM and nab-PTX would be continued for up to 24 weeks. The phase II part is an open-label, single-arm study. The maximum tolerated dose (MTD) of AM80 with GEM and nab-PTX, determined in phase I, would be administered until intolerable toxicity or disease progression occurs, up to a maximum of 24 weeks, to confirm efficacy and safety.The primary endpoints are frequency of DLT and MTD of AM80 with GEM and nab-PTX in the phase I part and response rate based on the RECIST in the phase II part. Given the historical control data, we hope that the response rate will be over 23% in phase II.DiscussionStrategies to convert pCAFs into rCAFs have been developed in recent years. We hypothesised that AM80 would be a promising enhancer of chemosensitivity and drug distribution through CAF conversion in the stroma.Trial registrationClinicaltrial.gov: NCT05064618, registered on 1 October 2021.jRCT: jRCT2041210056, registered on 27 August 2021.

CTIM-29. CLINICAL EVALUATION OF CHLOROTOXIN-DIRECTED CAR T CELLS FOR PATIENTS WITH RECURRENT GLIOBLASTOMA

Abstract Chlorotoxin (CLTX), a peptide component of scorpion venom, exhibits selective and broad binding to glioblastoma (GBM) and other tumors with minimal activity against non-malignant cells. We have developed a novel CAR that utilizes CLTX as the tumor targeting domain. Preclinical studies established that CLTX-CAR T cells target GBM through recognition of a receptor complex incorporating membrane-bound matrix metalloprotease-2 (MMP-2). Here, we report initial clinical findings for our phase I trial evaluating safety and bioactivity of CLTX-CAR T cells in patients with MMP2+ recurrent GBM (NCT04214392). Weekly infusions of CLTX-CAR T cells are delivered locoregionally, either directly into the tumor cavity (ICT; Arm 1), or in combination with intracerebroventricular (ICV) delivery (dual ICT/ICV; Arm 2). At this interim analysis, four participants have received at least three cycles of CLTX-CAR T cells ICT (Arm 1; 3-8 cycles) at dose level 1 (DL1; 4M, 20M, 20M CAR T cells per cycle). None of the participants experienced dose limiting toxicity (DLT) during the DLT evaluation period of 28-days, although one participant experienced a serious adverse event of grade 3 cerebral edema, possibly attributed to CAR T cells. Overall, Arm 1-DL1 was well-tolerated, and the next patient cohort will be treated on Arm 2-DL1 (dual ICT/ICV; 8M, 40M, 40M CAR T cells per cycle), as per protocol design. Disease response was assessed by RANO, overall survival, and time to progression; three of four participants achieved a best response of stable disease. Liquid biopsy detected persistent CAR T cells in the tumor cavity throughout treatment, suggesting that the therapeutic cells are not immunogenic. Ongoing studies are evaluating biomarkers of response and resistance, including CAR T cell activation and inflammatory cytokines. This clinical study provides first-in-human evidence for the safety and feasibility of CLTX-CAR T cells as a new class of toxin-based CARs for treatment of GBM.

Novel Combination Therapy of Venetoclax and Ruxolitinib in the Treatment of Patients with Relapsed/Refractory Acute Myeloid Leukemia

Novel Combination Therapy of Venetoclax and Ruxolitinib in the Treatment of Patients with Relapsed/Refractory Acute Myeloid Leukemia

Subcutaneous Epcoritamab in Patients with Relapsed/Refractory Chronic Lymphocytic Leukemia: Preliminary Results from the Epcore CLL-1 Trial

Background: Small molecules such as Bruton tyrosine kinase (BTK) and B-cell lymphoma 2 (BCL2) inhibitors have transformed the management of chronic lymphocytic leukemia (CLL). However, such treatments are not curative, and patients (pts) with relapsed or refractory (R/R) CLL following multiple targeted treatments present an emergent challenge with very limited therapeutic options. In addition, success rates of autologous T-cell-based therapies in CLL have been disappointing. In vitro data in CLL cells suggest potentially high efficacy of bispecific T-cell engagers (Martens et al, J Immunother Cancer 2020), but clinical data are extremely limited.Epcoritamab (GEN3013; DuoBody ®-CD3×CD20) is a bispecific antibody that can induce potent activation and cytotoxic activity of CD4+ and CD8+ T cells to specifically eliminate CD20-expressing cells (van der Horst et al, Blood Cancer J 2021). In the first-in-human trial in R/R B-cell non-Hodgkin lymphoma (B-NHL; EPCORE NHL-1; NCT03625037), epcoritamab showed manageable safety and meaningful antitumor activity across a range of aggressive and indolent B-NHLs. The most common treatment-emergent adverse events (AEs) were pyrexia (69%), cytokine release syndrome (CRS; 59%), and injection-site reaction (47%); CRS events were all grade 1-2 and most occurred in cycle 1 (Clausen et al, J Clin Oncol 2021). However, as CLL is characterized by presence of (high numbers of) circulating tumor cells, acquired T-cell dysfunction, and variable expression of CD20, data obtained in B-NHL are difficult to extrapolate to CLL. Herein we present the first results from the dose-escalation part of a phase 1b/2 trial evaluating epcoritamab in pts with R/R CLL.Methods: In this open-label, multicenter, phase 1b/2 trial, toxicity and efficacy of epcoritamab are investigated in adults with R/R CLL (EPCORE CLL-1; NCT04623541). Eligible pts previously received ≥2 lines of systemic antineoplastic therapy, including treatment with (or intolerance to) a BTK inhibitor. Epcoritamab is subcutaneously administered via 1-mL injections in 4-week cycles as follows: once weekly in cycles 1-3, every 2 weeks in cycles 4-9, and monthly in cycles ≥10 until progression or unacceptable toxicity. Step-up dosing during cycle 1 (ie, priming dose followed by an intermediate dose, then full doses) is used in combination with steroid prophylaxis to reduce the risk of CRS. In the dose-escalation part, pts with R/R CLL received epcoritamab at 2 full-dose levels (24 and 48 mg) according to a modified 3+3 design. Primary end points of the dose-escalation part included dose-limiting toxicities (DLTs) during the first 28-day treatment cycle and the incidence and severity of AEs, CRS, immune effector cell-associated neurotoxicity syndrome (ICANS), and tumor lysis syndrome (TLS).Results: The first pt was enrolled on November 30, 2020. As of July 12, 2021, 7 pts with R/R CLL received epcoritamab subcutaneously administered at 2 full-dose levels: 24 mg (n=3) and 48 mg (n=4). Six pts completed the DLT evaluation period, and 5 pts had a full response assessment. Pts had received a median of 4 lines of prior therapy (range, 2-5). Six of 7 pts had poor-risk features of del(17p), TP53 mutations, or both. Three of 7 pts had bulky disease.No DLTs occurred at 24 or 48 mg. The most common treatment-emergent AEs (>30%) were CRS (100%), fatigue (71%), injection-site reaction (43%), and nausea (43%). All pts experienced CRS in the first cycle, but no CRS events were higher than grade 2. No cases of ICANS were observed. TLS was not observed. Antileukemic activity has been observed at both dose levels, with partial responses in 3 of 5 pts. Updated clinical and pharmacokinetic data, including data for additional pts treated with epcoritamab, will be presented.Conclusions: These data suggest that epcoritamab is well tolerated in pts with R/R CLL at dose levels up to 48 mg and has clinical activity in pts with high-risk features. The expansion part of this study in pts with R/R CLL and Richter syndrome will open later this year. DisclosuresKater: Janssen, AstraZeneca: Other: Ad Board, steering committee, Research Funding; BMS, Roche/Genentech: Other: Ad Board, , Research Funding; Genmab, LAVA: Other: Ad Board, Steering Committee; Abbvie: Honoraria, Other: Ad Board, Research Funding. Niemann: CSL Behring, Genmab, Takeda, Octapharma: Consultancy; Abbvie, AstraZeneca, Janssen: Consultancy, Research Funding; Novo Nordisk Foundation: Research Funding. Hutchings: Roche: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Novartis: Research Funding; Incyte: Research Funding; Janssen: Honoraria, Research Funding; Genmab: Consultancy, Honoraria, Research Funding; Celgene: Research Funding; Genentech: Honoraria, Research Funding. Chen: Genmab: Current Employment. Rios: Genmab: Current Employment. Palenski: AbbVie: Current Employment. Li: Genmab: Current Employment. Mato: AbbVie: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; MSKCC: Current Employment; Genmab: Research Funding; Johnson and Johnson: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; LOXO: Consultancy, Research Funding; Nurix: Research Funding; DTRM BioPharma: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding; BeiGene: Consultancy, Research Funding; Acerta/AstraZeneca: Consultancy, Research Funding; AstraZeneca: Consultancy; Sunesis: Consultancy, Research Funding.

FLT3-Mutated Acute Myeloid Leukemia Using a Novel Regimen of Gemtuzumab Ozogamicin and Midostaurin in Combination with Standard Cytarabine and Daunorubicin Induction Therapy

FLT3-Mutated Acute Myeloid Leukemia Using a Novel Regimen of Gemtuzumab Ozogamicin and Midostaurin in Combination with Standard Cytarabine and Daunorubicin Induction Therapy

434P CodeBreaK 101 subprotocol H: Phase Ib study evaluating combination of sotorasib (Soto), a KRASG12C inhibitor, and panitumumab (PMab), an EGFR inhibitor, in advanced KRAS p.G12C-mutated colorectal cancer (CRC)

Soto, a specific, irreversible KRASG12C inhibitor, has monotherapy clinical activity in KRAS p.G12C-mutated solid tumors, with an objective response rate of 7.1% for heavily pretreated CRC in the CodeBreaK 100 phase I trial. KRASG12C blockade can lead to accumulation of activated EGFR. Combining Soto with an EGFR inhibitor may produce synergistic antitumor activity. The safety and efficacy of Soto with PMab, a monoclonal antibody specific to EGFR, in KRAS p.G12C-mutated CRC are being evaluated in this ongoing phase Ib study (NCT04185883). This study includes a dose exploration phase to identify a safe/tolerable daily oral dose of Soto with PMab (6mg/kg IV Q2W) in patients (pts) with previously treated mCRC, and a dose expansion phase. Dose exploration is reported. As of 4/23/21, 8 pts (5 female, median age: 60.5 yrs [range: 31-79]) were enrolled in dose exploration with 960 mg QD Soto and 6mg/kg IV Q2W PMab. Median number of lines of therapy for metastatic disease was 3.5 (range 1-10); 5 pts had prior Soto. Median treatment (tx) duration was 4.4 months (range: 1.4, 8.8). No dose limiting toxicities (DLTs) were observed during the DLT evaluation period (first 28 days). Tx-related adverse events (TRAEs) of any grade related to Soto or PMab were reported for 4 and 8 pts, respectively. No grade 4 or fatal TRAEs occurred. Two pts had PMab TRAEs leading to dose modification of PMab (1–dermatitis acneiform, 1–dry skin, rash, hypokalemia, hypomagnesemia) and 1 pt had a Soto TRAE leading to dose modification of Soto (diarrhea). There was 1 confirmed partial response, 5 stable disease (SD), 1 progressive disease (PD), and 1 not evaluated but with clinical PD. Of pts with prior Soto, 4 had decrease in sum of target lesions; 4 had SD and 1 with PD developed new lesions despite a decrease in size of target lesions. Sotorasib exposures were similar to those observed in monotherapy study. Combination of Soto (960 mg QD) and PMab (6mg/kg IV Q2W) was safe and tolerable with promising efficacy in heavily pretreated pts with KRAS p.G12C-mutated CRC. AEs are consistent with known AEs for Soto and PMab. Updated safety and efficacy data will be presented.

Abstract CT215: A Phase 1 Study of INCB057643 Monotherapy in Patients with Relapsed or Refractory Myelofibrosis (INCB 57643-103)

Abstract Background: Many neoplasms including myelofibrosis (MF) are associated with activation of transcription factors that regulate oncogenic processes. These may respond to inhibition of bromodomain and extra-terminal domain (BET) protein. In the first-in-human study INCB 57643-101, the BET inhibitor INCB057643, was generally safe and tolerable as monotherapy, and demonstrated preliminary efficacy in patients (pts) with MF as monotherapy or combined with the JAK inhibitor, ruxolitinib (Falchook G, et al. Clin Cancer Res. 2020). This phase 1, open-label, two-part dose confirmation and expansion study further evaluates the safety and tolerability of INCB057643 monotherapy in pts with relapsed/refractory MF (INCB 57643-103; NCT04279847). Methods: Eligible pts must be ≥18 y with histologically confirmed primary or secondary MF (post-polycythemia vera, post-essential thrombocythemia), have received ≥1 prior therapy including ruxolitinib, have no known clinically beneficial therapy available, have intermediate-2/high risk disease by Dynamic International Prognostic Scoring System, have ECOG PS 0-2, life expectancy ≥24 wks, and willing to provide a bone marrow biopsy and/or aspirate at baseline (or archival sample obtained after most recent therapy). Exclusion criteria include prior BET inhibitor or anticancer treatment within specified intervals before first dose; concurrent anticancer therapy; allogeneic hematopoietic stem cell transplant (allo-HSCT) ≤6 months before enrollment; active graft versus host disease or immunosuppressive therapy after allo-HSCT ≤2 wks before first-dose; significant and uncontrolled disease (eg, gastrointestinal, cardiovascular); history of bleeding disorders, high risk of bleeding, or abnormal hematologic, hepatic, renal, coagulation, or metabolic laboratory values. In part 1, ≤6 pts will receive oral INCB057643 4 mg once-daily (QD) continuously. Doses will be deemed tolerable if ≤2 pts experience dose-limiting toxicities (DLTs) and ≤2 pts discontinue due to treatment-related adverse events (TRAEs) during the DLT evaluation period. Part 2 will further characterize safety and tolerability as well as evaluate preliminary efficacy of INCB057643 in ≤9 pts. The starting dose will be 4 mg QD if tolerated in Part 1, and 2 mg QD if not. Treatment may continue if clinically beneficial and discontinuation criteria are not met. The primary objective is to determine safety and tolerability of INCB057643 monotherapy. Secondary objectives are to evaluate anemia response by International Working Group-Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) and European LeukemiaNet Consensus Report (ELN), transfusion dependence, spleen volume, rate and duration of spleen response by IWG-MRT and ELN, and impact on quality of life. Pts will be assessed every 3 cycles and will receive follow-up for safety for 30-35 days after last dose. Citation Format: Pankit Vachhani, Christine Lihou, Gongfu Zhou, Fred Zheng. A Phase 1 Study of INCB057643 Monotherapy in Patients with Relapsed or Refractory Myelofibrosis (INCB 57643-103) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT215.