Dose-limiting Toxicity Evaluation Research Articles

Safety results of Q-1802, a Claudin18.2/PD-L1 bsABs, in patients with relapsed or refractory solid tumors in a phase 1 study.

2568 Background: Q-1802 is a humanized bispecific antibody that targets both the tumor -specific antigen CLDN18.2 and the immune checkpoint PD-L1. Methods: This is a first-in-human, phase 1a/1b, multicenter, dose escalation and dose expansion study of Q-1802 administered intravenously to adult pts with resistant/refractory advanced or metastatic solid tumors who had failed standard therapies. Monotherapy of Q-1802 was conducted in 20-30 enrolled subjects. In the dose escalation phase (phase 1a), an accelerated titration followed by a 3+3 design was used to assess the safety and tolerability of Q-1802 monotherapy (dose range 0.1 mg/kg to 20 mg/kg); and determine the maximum tolerated dose (MTD). Q-1802 was administered Q3w on a 21-day treatment cycle and dose limiting toxicity (DLT) observation period. Tumor assessments per RECIST v1.1 were performed once every 6 weeks (2 cycles). Q-1802 PK and PD analyses were performed. Results: As of Jan 20, 2022, a total of 9 patients (median age 57y; most patients received ≥3 prior regimens) were enrolled in phase 1a with DLT evaluation of the 20 mg/kg cohort currently in progress. The most common tumor types were GI cancers. There were no DLTs up to 10 mg/kg of Q-1802, inclusive. Phase 1a with DLT evaluation of the 20 mg/kg cohort currently in progress. The most common treatment related adverse events (TRAEs) were Gastrointestinal AE (66.7%, 6/9), including nausea 6/9 (66.7%), vomiting 5/9 (55.6%), abdominal pain 2/9 (22.2%) and diarrhea 2/9 (22.2%). The second common TRAEs were IRR (infusion related reaction) (33.3%, 3/9), including Fatigue 3/9 (33.3%), Fever 2/9 (22.2%), Chill 2/9 (22.2%), face pain 1/9 (11.1%). There was G1/2 except for one patient experienced a G3 skin rash, and one patient reported with a G3 Gastrointestinal AE. Two SAEs (G2 fever and G3 Gastrointestinal AE) were reported, both were considered as possibly related to study drug, but recovered shortly. No death reported due to study related treatment. Safety evaluation of the 20 mg/kg dose level is in progress. One Gastric cancer patient (moderate CLDN18.2 expression at baseline) with prior heavily treatment observed clinical benefit and response with Non-CR/Non-PD at first tumor assessment at dose of 10mg/kg and continues the therapy. Q-1802 drug exposure increased with increasing dose. The elimination of Q-1802 appears to follow first-order elimination kinetics. Conclusions: Q-1802 bsABs has presented safe and well-tolerated profile up to doses of 10 mg/kg. The dose escalation is still in progress. Clinical trial information: NCT04856150.

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.

A phase I study of FLOT as first-line treatment for advanced gastric cancer with/without severe peritoneal metastasis: Results of dose-finding part.

298 Background: Although FLOT (5-fluorouracil [5-FU]/leucovorin [ l-LV] + oxaliplatin [L-OHP] + docetaxel [DTX]) is globally recognized as the standard treatment for gastric cancer (GC), the safety of FLOT in Japanese patients (pts) is unknown. Moreover, because advanced GC (AGC) pts with severe peritoneal metastasis (SPM) have often been excluded from pivotal clinical trials due to their poor condition, it is necessary to develop standardized treatment for them. Methods: This study is an open-label, multicenter, single-arm, phase I study to determine the recommended phase II dose (RP2D) of FLOT for Japanese AGC pts without (part 1) or with (part 2) SPM using a 3 + 3 design. Main eligibility criteria included histologically confirmed AGC, HER2 negative, and age 20–75 years. In part 2a, pts with ECOG Performance status (PS) 2, who simultaneously had massive ascites and inadequate oral intake, were excluded. Massive ascites was defined as continuous ascites from the pelvic cavity to the upper abdomen, based on computed tomography findings. Inadequate oral intake was defined as the requirement for daily intravenous infusions to supply water or nutrition. The dose limiting toxicity (DLT) was assessed before the start of cycle 2. The fixed dose of L-OHP, l-LV, and 5-FU was 85, 200, and 2600 mg/m2, respectively, and DTX was administered at a dose of 50, 40, and 30 mg/m2 in the level 0, −1, and −2, respectively. Results: In part 1a, one patient died of hemorrhage from the primary tumor on Cycle 1 Day 2 and was replaced. The characteristics were as follows: median age (range), 70 (51–71) years; male/female, 2/1; ECOG PS (0/1), 2/1; histological type (diffuse/intestinal), 3/0; prior gastrectomy (yes/no), 0/3; and measurable lesions (yes/no), 1/2. During DLT evaluation, grade 3 (G3) or higher adverse events (AEs) were neutropenia (n = 1), lymphocytopenia (n = 1), anemia (n = 1), and anorexia (n = 1). During follow-up, the most common G3 or higher AEs included neutropenia (n = 3), lymphocytopenia (n = 1), anemia (n = 1), febrile neutropenia (FN) (n = 1 at cycle 5), diarrhea (n = 1), anorexia (n = 1), fatigue (n = 1), and colonic perforation (n = 1) due to diverticulitis (not treatment-related AE). In part 2a, the characteristics were as follows: median age (range) 64 (49–69) years; male/female, 3/0; ECOG PS (0/1), 0/3; histological type (diffuse/intestinal), 3/0; prior gastrectomy (yes/no), 0/3; and measurable lesions (yes/no), 0/3. Two pts had massive ascites and 1 pt had both massive ascites and inadequate oral intake. During follow-up, only G3 neutropenia (n = 3) was observed. Two pts needed dose modification in cycle 2. Both in part 1a and 2a, no treatment-related deaths and no DLTs were observed and the RP2D was determined in level 0. Conclusions: We determined that DTX 50 mg/m2, L-OHP 85 mg/m2, 5-FU 2600 mg/m2, and l-LV 200 mg/m2 were the RP2D of FLOT for Japanese AGC with/without SPM. Clinical trial information: 041200044.

Preclinical and clinical researches of Denileukin Diftitox (Genetical Recombination) (Remitoro®), a novel agent for T-cell lymphoma

Denileukin Diftitox (DD) is a recombinant fusion protein of diphtheria toxin (DT) fragments and human interleukin-2 (IL-2). DD binds to IL-2 receptor (IL-2R) expressed on tumor cells and is taken up into the cells. Subsequently, DT fragments with adenosine diphosphate ribosylation enzyme inhibit protein synthesis, then ultimately trigger cell death. DD binds to both high- and intermediate-affinity IL-2Rs via IL-2 domain and inhibits growth of human T-cell lymphomas cell lines. E7777, which contains DD as an active component, has improved purity and an increased percentage of active monomer compared with the approved drug E7272 (ONTAK in the US, not approved in Japan). In the phase I clinical study in Japanese patients with relapsed or refractory peripheral T-cell lymphoma (PTCL) and cutaneous T-cell lymphoma (CTCL), the maximum tolerated dose and recommended dose of E7777 were 9 μg/kg/day (administered on Days 1-5 of each cycle) based on the evaluation of dose-limiting toxicity. In the phase II clinical study, the objective response rate was 36.1%, showing comparable efficacy to existing therapies. E7777 showed anti-tumor activity observed across the range of CD25 expression. Grade 3 or higher adverse events (AE) occurred in 94.6%, and serious AE such as capillary leak syndrome and rhabdomyolysis were reported. Therefore, safety monitoring activities have been continued along with alerting related events. Based on these results, E7777 obtained a new drug approval in Japan in March 2021 for the indication of relapsed or refractory PTCL/CTCL.

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

Atezolizumab Combined with Immunogenic Salvage Chemoimmunotherapy (R-GemOx+Atezo) in Patients with Transformed Diffuse Large B-Cell Lymphoma

Atezolizumab Combined with Immunogenic Salvage Chemoimmunotherapy (R-GemOx+Atezo) in Patients with Transformed Diffuse Large B-Cell Lymphoma

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.

A Phase 1 Trial of Alisertib and Romidepsin for Relapsed/Refractory Aggressive B-Cell and T-Cell Lymphomas

A Phase 1 Trial of Alisertib and Romidepsin for Relapsed/Refractory Aggressive B-Cell and T-Cell Lymphomas

Safety of AK117, an anti-CD47 monoclonal antibody, in patients with advanced or metastatic solid tumors in a phase I study.

2630 Background: AK117 is a novel humanized IgG4 monoclonal antibody (mAb) targeting CD47, a macrophage immune checkpoint that allows tumor cells to evade immune destruction by phagocytic cells. CD47 is a target expressed in many cancers. However, the initial dose of anti-CD47 therapy may be limited by severe anemia due to ubiquitous CD47 expression on senescent red blood cells (RBCs). Here, we present encouraging preliminary AK117 safety and receptor occupancy (RO) data from an ongoing dose-escalation study in patients (pts) with advanced or metastatic solid tumors. Methods: This is a first-in-human, phase 1a/1b, multicenter, open label, single arm, dose escalation and dose expansion study of AK117 administered intravenously to adult pts with resistant/refractory advanced or metastatic solid tumors or lymphomas. In the dose escalation phase (phase 1a), an accelerated titration followed by a 3+3+3 design was used to assess the safety and tolerability of AK117 monotherapy (dose range 0.3 mg/kg to 45 mg/kg); and determine the maximum tolerated dose (MTD). AK117 was administered QW on a 28-day treatment cycle and dose limiting toxicity (DLT) observation period. Tumor assessments per RECIST v1.1 were performed once every 8 weeks (2 cycles). Results: As of 15 Feb 2021, 15 pts were enrolled in phase 1a with DLT evaluation of the 30 mg/kg cohort currently in progress. There were no DLTs up to 20 mg/kg QW AK117, inclusive. Five treatment-related adverse events (TRAEs) occurred in 4 subjects as shown in the table below. All pts with TRAEs continue to receive AK117, except the pt on 1 mg/kg AK117 who discontinued due to disease progression. G2 anemia and G1 thrombocytopenia occurred after Cycle 1 in a pt (liposarcoma, 10 mg/kg cohort), who had a medical history of anemia (hemoglobin 119 g/L at screening). No hematological TRAEs were seen in other pts, including those who received 20 mg/kg AK117 QW. There were no infusion-related reactions (IRRs) or grade ≥ 3 TRAEs. Target engagement in the periphery was confirmed by measuring CD47 RO of AK117 on RBCs and T lymphocytes. 100% RO on RBCs and T lymphocytes was achieved after the first dose and continued to Day 8 (prior to second dose) in the 10 mg/kg and 20 mg/kg cohorts. Conclusions: AK117 is safe and well-tolerated up to 20 mg/kg QW, inclusive, with no IRRs or severe TRAEs observed. There were no hematological TRAEs, except in a pt with baseline G1 anemia receiving 10 mg/kg AK117. Unlike other anti-CD47 therapies, AK117 does not require a lower ‘priming’ dose to prevent anemia. Safety evaluation of the 30 mg/kg dose level is in progress. Full and durable RO in the periphery was seen at 10 mg/kg and above. Further evaluation of AK117 in combination with AK104, an anti-PD-1/CTLA-4 bispecific antibody, shall commence imminently. Clinical trial information: NCT04349969. [Table: see text]

A phase 1/2 study of olaparib and radium-223 in men with metastatic castration-resistant prostate cancer (mCRPC) with bone metastases (COMRADE): Results of the phase 1 study.

e17020 Background: Radium-223 is an α-emitting radioisotope that induces DNA double-stranded breaks leading to cell death and has improved survival in mCRPC. In preclinical models, PARP inhibitors have shown efficacy as radiosensitizing agents. We designed a phase 1/2 trial to test the hypothesis that radium-223 + olaparib will demonstrate anti-tumor activity in mCRPC irrespective of homologous recombination repair deficiency (HRD) status. Methods: This is an open label, multi-center, phase 1/2 study (NCT03317392) evaluating the dosing, safety and efficacy of radium-223 + olaparib. Eligible patients (pts) had mCRPC with ≥2 bone metastases without visceral metastases or lymphadenopathy > 4 cm. There was no limit on prior therapy. All pts had a baseline biopsy. The phase 1 used a 3+3 dose escalation design with fixed dose radium-223 (55 kBq/kg IV every 4 weeks x 6). Dose level 1 (DL1) was olaparib 200 mg PO BID; DL2 was olaparib 300 mg PO BID. The primary objective was to determine the recommended phase 2 dose (RP2D) and safety. The dose limiting toxicities (DLT) evaluation period was 2 cycles (1 cycle=28 days). Secondary endpoints included radiographic progression-free survival (rPFS) defined by PCWG3 criteria, PSA response (50% decline from baseline), and alkaline phosphatase response (30% decline from baseline). Results: 12 pts were enrolled on the phase 1. Median age was 68 (range 59-81) years. Median prior lines of CRPC therapies was 2 (1-5), including 3 (25%) who had received prior chemotherapy and 100% a prior novel hormone therapy. 6 pts were enrolled at DL1. 1 patient experienced a DLT outside the DLT evaluation period. 3 pts had grade (G) 3-4 treatment-related adverse events (TrAE) including G3 anemia (n=2) and G3 thrombocytopenia (n=1). No patient underwent dose reductions at DL1. 6 pts were enrolled at DL2. 1 patient experienced a DLT outside the DLT evaluation period. 2 pts had G3-4 TrAE including G3 anemia and G4 lymphocytopenia (n=1) and G3 stroke (n=1). 5 underwent dose reductions at DL2. There were no G5 events. Reason for treatment discontinuation is in the table below. After review of safety data, the safety monitoring committee deemed the RP2D of olaparib at 200 mg BID when combined with radium-223. Overall, PSA response and alkaline phosphatase response were 16.7% (n=2, 1 at DL1, 1 at DL2) and 67% (n=8, 3 at DL1, 5 at DL2), respectively. Median follow-up was 6.5 (range 2.8, 11.8) months, and 6-month rPFS was 57% (95% CI: 25%, 80%). Conclusions: We demonstrate that olaparib can be safety combined with radium-223 with RP2 dose of 200 mg BID. The phase 2 study of radium-223 +/- olaparib is accruing (target 120 pts). Outcomes by HRD status will be presented. Clinical trial information: NCT03317392. [Table: see text]

A phase 1b study of once‐weekly carfilzomib combined with lenalidomide and dexamethasone in patients with newly diagnosed multiple myeloma

Twice‐weekly carfilzomib with lenalidomide‐dexamethasone (Rd) is an effective regimen for newly diagnosed multiple myeloma (NDMM). Here we evaluated once‐weekly carfilzomib with Rd (once‐weekly KRd) in NDMM patients. The NDMM patients were enrolled regardless of transplant eligibility. Patients received carfilzomib on days 1, 8, and 15; lenalidomide 25 mg on days 1‐21; and dexamethasone 40 mg on carfilzomib days (also day 22 for cycles 1‐8) for ≤18, 28‐day cycles. Enrollment initiated in a carfilzomib 20/70 mg/m2 (20 mg/m2 on cycle one, day 1; 70 mg/m2 thereafter) NDMM dose‐expansion arm, which was suspended because of serious adverse events. After evaluation of dose‐limiting toxicities in a two‐step‐up dose‐evaluation cohort, an NDMM dose‐expansion arm (carfilzomib 20/56 mg/m2) was opened. Fifty‐one NDMM patients were enrolled in dose‐finding and dose‐expansion cohorts. Results are presented for the carfilzomib 56 mg/m2 NDMM dose‐expansion arm (n = 33). The grade ≥ 3 treatment‐emergent AE (TEAE) rate was 63.6%. Twenty‐five patients underwent stem cell collection; 18 proceeded to auto stem cell transplant, and five resumed KRd on study after autoSCT. The overall response rate (ORR) based on best overall response by cycle four was 97.0% (≥very good partial response [VGPR], 69.7%) in the NDMM 20/56 mg/m2 cohort. In patients who did not receive autoSCT (n = 15), the median number of cycles was 16.0; ORR was 93.3% (≥VGPR, 80.0%). At a median follow‐up of 8.1 months, median progression‐free survival was not reached. Once‐weekly KRd (carfilzomib 56 mg/m2) had a favorable safety profile and promising activity in NDMM, supporting the use of this regimen in this setting.

HM43239, a Novel Small Molecule Inhibitor of FLT3, in Acute Myeloid Leukemia (AML) with and without FMS-like Tyrosine Kinase 3 (FLT3) Mutations: Phase 1/2 Study

HM43239, a Novel Small Molecule Inhibitor of FLT3, in Acute Myeloid Leukemia (AML) with and without FMS-like Tyrosine Kinase 3 (FLT3) Mutations: Phase 1/2 Study

Trial in Progress: A Phase I Trial of BTX-A51 in Patients with Relapsed or Refractory AML or High-Risk MDS

Background: For patients with relapsed or refractory (R/R) acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (MDS), low response rates and poor overall survival remain unmet clinical needs. AML cells evade apoptosis through overexpression of antiapoptotic genes and inactivation of p53. The antiapoptotic gene Mcl1 is overexpressed in AML cell lines resistant to venetoclax. Similarly, the sensitivity of AML patients' samples to venetoclax inversely correlates with the presence of a TP53 mutation or low expression of p53. In AML, p53 inactivation more commonly results from overexpression of its negative regulators, Mdmx and Mdm2. BTX-A51 is a novel, oral, direct inhibitor of Casein kinase 1α (CK1α), cyclin dependent kinase 7 (CDK7), and CDK9. CK1α phosphorylates Mdmx and Mdm2 leading to enhanced binding and degradation of p53. CDK7 and CDK9 phosphorylate RNA polymerase II (Pol II) to enable transcriptional initiation and elongation, particularly at large clusters of transcriptional enhancers termed super-enhancers (SE). Preclinical studies have demonstrated that BTX-A51 robustly increased p53 protein levels via CK1a inhibition and Mdm2 downregulation while preferentially decreasing SE transcription of key oncogenes such as Myc andMcl1, enabling selective apoptosis of leukemia cells. The combination of CK1α, CDK7, and CDK9 inhibition was synergistic and prolonged survival in multiple genetic and patient-derived xenograft AML models. Study Design and Methods: This is an open-label, multi-center, first-in-human Phase 1 study evaluating the safety of BTX-A51 in patients with R/R AML or high-risk MDS. The trial will be performed in two phases, a dose escalation (phase 1a) and dose expansion (phase 1b). Phase 1a utilizes a hybrid accelerated titration with single patient cohorts and a Bayesian optimal interval (BOIN) design to assess 8 potential dosing cohorts. The maximum tolerated dose (MTD) will be the dose for which the isotonic estimate of the toxicity rate is closest to the target toxicity rate of 0.3. Up to a maximum of 35 patients will be enrolled in the dose escalation phase of the study at Memorial Sloan Kettering Cancer Center, MD Anderson Cancer Center, and City of Hope Cancer Center. Following determination of the MTD, 15 patients will be enrolled in the dose expansion phase for further evaluation of dose-limiting toxicities (DLTs) and for preliminary evidence of efficacy. BTX-A51 will be dosed 3 weeks on drug, followed by 1 week off drug over a 28-day cycle. For the first cycle, patients will receive tumor lysis syndrome prophylaxis with allopurinol and intravenous fluids and be closely monitored. Key inclusion criteria are age ³ 18 years, R/R AML or R/R high-risk MDS, Eastern Cooperative Oncology Group (ECOG) £ 2 and life expectancy of ³ 6 weeks, and adequate kidney and liver function. Key exclusion criteria are receipt of cancer chemotherapy (other than hydroxyurea) within 2 weeks prior to the start of study drug, transplantation within 3 months prior to screening, active graft-versus-host disease requiring systemic immunosuppressive medications, and a white blood cell count > 20 × 109/L. The primary objective for the Phase 1 study is to determine the MTD and recommended Phase 2 dose (RP2D) of BTX-A51. Secondary objectives include evaluating overall response (complete remission, complete remission with incomplete blood count recovery, and partial remission) according to the European LeukemiaNet (ELN) 2017 criteria (Döhner et al. Blood. 2017), survival (overall survival and event-free survival) and pharmacokinetics. Correlative objectives include determining the changes in SEs and SE-driven expression of antiapoptotic genes by chromatin immunoprecipitation and RNA-sequencing. Recruitment is ongoing and this trial is registered on clinicaltrials.gov: NCT04243785 Disclosures Stein: Amgen: Consultancy, Speakers Bureau; Stemline: Consultancy, Speakers Bureau. Borthakur:BioLine Rx: Consultancy; Argenx: Consultancy; PTC Therapeutics: Consultancy; FTC Therapeutics: Consultancy; BioTherix: Consultancy; Curio Science LLC: Consultancy; Xbiotech USA: Research Funding; Oncoceutics: Research Funding; Polaris: Research Funding; PTC Therapeutics: Research Funding; Cyclacel: Research Funding; GSK: Research Funding; Jannsen: Research Funding; Abbvie: Research Funding; Novartis: Research Funding; Incyte: Research Funding; BioLine Rx: Research Funding; BMS: Research Funding; AstraZeneca: Research Funding; Nkarta Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy. Murray:Salamandra: Current Employment. Kook:Salamandra: Current Employment. Chan:BioTheryx: Current Employment. Stein:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Syros: Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Research Funding; Biotheryx: Consultancy; Agios Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy; PTC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy; Amgen: Consultancy; Celgene Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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

Background: Activation of transcription factors that regulate oncogenic processes is frequently observed in cancers such as myelofibrosis (MF). In preclinical studies, tumors associated with dysregulation of transcription factors appear to be responsive to inhibition of bromodomain and extra-terminal motif (BET) protein [Delmore JE, et al. Cell 2011; Shimamura T, et al. Clin Cancer Res 2013]. In addition to exerting a direct effect on tumor cells, BET inhibitors may also modulate tumorigenic inflammation; in a mouse model of MF, BET inhibition in combination with the Janus kinase inhibitor ruxolitinib resulted in decreased inflammation and reduced disease burden [Kleppe M, et al. Cancer Cell 2018]. In the first-in-human study INCB 57643-101, the small-molecule BET inhibitor INCB057643, was safe and generally well tolerated as monotherapy, and demonstrated preliminary efficacy in 2 out of 3 patients with MF when administered alone or in combination with ruxolitinib [Falchook G, et al. Clin Cancer Res 2020]. The INCB 57643-103 trial is designed to further evaluate the safety and tolerability of INCB057643 monotherapy in patients with relapsed or refractory MF. Methods: INCB 57643-103 (NCT04279847) is a phase 1, single-arm, open-label, two-part dose confirmation and expansion study evaluating INCB057643 in patients with measurable histologically or cytologically confirmed (World Health Organization criteria 2016), relapsed or refractory primary MF or secondary MF (post-polycythemia vera, post-essential thrombocythemia). Patients must be ≥18 years of age, have received ≥1 line of prior therapy including ruxolitinib and have no option for therapy known to provide clinical benefit, have a risk category of intermediate-2 or high according to the Dynamic International Prognostic Scoring System, have an Eastern Cooperative Oncology Group performance status 0-2, have a life expectancy of 24 weeks or more, and be willing to provide a pretreatment bone marrow biopsy and/or aspirate at baseline (or an archival sample obtained after most recent therapy). Patients will be excluded if they have received prior treatment with a BET inhibitor; received anticancer treatment within specified intervals before the first administration of study drug or receiving concurrent anticancer therapy; received allogeneic hematopoietic stem cell transplant (6 months or less before enrollment) or have active graft versus host disease or received immunosuppressive therapy after allogeneic transplant 2 weeks or less before study drug treatment; have significant and uncontrolled medical events such as gastrointestinal or cardiovascular; have a history of bleeding disorder or at a high risk of bleeding; or have abnormal hematologic, hepatic, renal, coagulation, or metabolic laboratory values. Approximately 15 patients will be enrolled. Part 1 will evaluate initial safety and tolerability of INCB057643. Up to 6 patients will self-administer oral INCB057643 4 mg once daily (QD) continuously. Doses will be declared tolerable if dose-limiting toxicities (DLT) occur in ≤2 patients and discontinuation due to treatment-related adverse events (TRAEs) occurs in ≤2 patients during the DLT evaluation period. Part 2 will further characterize safety and tolerability as well as evaluate preliminary efficacy. Up to 9 patients will receive INCB057643 at 4 mg QD if the dose is deemed tolerable in Part 1; if not, the starting dose will be 2 mg QD. Treatment may continue as long as benefit is derived and discontinuation criteria are not met. The primary study objective is assessment of safety and tolerability of INCB057643 monotherapy by monitoring the frequency and severity of AEs, performing physical examinations, and collecting vital signs and laboratory values. Secondary objectives include evaluation of anemia response by International Working Group-Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) and European LeukemiaNet (ELN) Consensus Report, red blood cell transfusion dependence, spleen volume, rate of spleen response and duration of spleen response by IWG-MRT and ELN Consensus Report, and impact on quality of life. Patients will be assessed every 3 cycles and will receive follow-up for safety for 30-35 days after last dose of study drug. Disclosures Lihou: Incyte: Current Employment, Current equity holder in publicly-traded company. Zhou:Incyte: Current Employment, Current equity holder in publicly-traded company. Zheng:Incyte: Current Employment, Current equity holder in publicly-traded company.

Phase 1 study of mTORC1/2 inhibitor sapanisertib (TAK-228) in advanced solid tumours, with an expansion phase in renal, endometrial or bladder cancer

BackgroundThis Phase 1 dose-escalation/expansion study assessed safety/tolerability of sapanisertib, an oral, highly selective inhibitor of mTORC1/mTORC2, in advanced solid tumours.MethodsEligible patients received increasing sapanisertib doses once daily (QD; 31 patients), once weekly (QW; 30 patients), QD for 3 days on/4 days off QW (QD × 3dQW; 33 patients) or QD for 5 days on/2 days off QW (QD × 5dQW; 22 patients). In expansion cohorts, 82 patients with renal cell carcinoma (RCC), endometrial or bladder cancer received sapanisertib 5 mg QD (39 patients), 40 mg QW (26 patients) or 30 mg QW (17 patients).ResultsMaximum tolerated doses of sapanisertib were 6 mg QD, 40 mg QW, 9 mg QD × 3dQW and 7 mg QD × 5dQW. Frequent dose-limiting toxicities (DLTs) included hyperglycaemia, maculo-papular rash (QD), asthenia and stomatitis (QD × 3dQW/QD × 5dQW); expansion phase doses of 5 mg QD and 30 mg QW were selected based on tolerability beyond the DLT evaluation period. One patient with RCC achieved complete response; nine experienced partial responses (RCC: seven patients; carcinoid tumour/endometrial cancer: one patient each). Sapanisertib pharmacokinetics were time-linear and supported multiple dosing. Pharmacodynamic findings demonstrated treatment-related reductions in TORC1/2 biomarkers.ConclusionsSapanisertib demonstrated a manageable safety profile, with preliminary antitumour activity observed in RCC and endometrial cancer.Clinical trial registrationClinicalTrials.gov, NCT01058707.