Expansion Cohort Research Articles

CTIM-28. NEOADJUVANT ANTI-PD1 IMMUNOTHERAPY FOR SURGICALLY ACCESSIBLE RECURRENT GLIOBLASTOMA: CLINICAL AND MOLECULAR OUTCOMES OF A STAGE 2 SINGLE-ARM EXPANSION COHORT

Abstract Glioblastoma is immunologically “cold” and resistant to single-agent immune-checkpoint inhibitors (ICI). Our previous study of neoadjuvant pembrolizumab in surgically-accessible recurrent glioblastoma identified a molecular signature of response to ICI and suggested that neoadjuvant pembrolizumab may improve survival. To increase the power of this observation, we performed bulk-RNA seq on resected tumor tissue from an additional 25 patients with recurrent glioblastoma treated with neoadjuvant pembrolizumab. Neoadjuvant pembrolizumab was associated with suppression of cell cycle/cancer proliferation genes and upregulation of T-cell/interferon-related gene expression. This signature was unique to patients treated with neoadjuvant pembrolizumab and was an independent positive risk factor for survival. PF6 for the stage 2 expansion cohort was 0%, while overall survival and progression-free survival were similar to historical controls at 6.8 months and 2.5 months, respectively. Our results demonstrate a clear pharmacodynamic effect of anti-PD1 therapy in glioblastoma and identify pathways that may mediate resistance. However, we did not observe a survival benefit to neoadjuvant pembrolizumab in recurrent glioblastoma in our expansion cohort. Our new data suggests some patients may exhibit innate resistance to pre-surgical ICI and require other concomitant therapies to sensitize effectively.

CTNI-32. A MULTICENTER PHASE 1 TRIAL OF TUCATINIB, TRASTUZUMAB, AND CAPECITABINE WITH STEREOTACTIC RADIOSURGERY IN PATIENTS WITH BRAIN METASTASES FROM HER2 POSITIVE BREAST CANCER (TUTOR)

Abstract BACKGROUND Nearly 20-40% of HER2+ breast cancer patients develop brain metastases (BMs), where stereotactic radiosurgery (SRS) is standard-for-care for local control. Tucatinib, an oral HER2-selective TKI, is safe and efficacious in HER2+ breast cancer in combination with capecitabine and trastuzumab. Synergism between these 3 drugs (TCT) and radiation may enhance DNA damage. This phase 1 trial aims to evaluate TCT plus SRS for HER2+ breast cancer BMs (BCBM). METHODS TUTOR is a pre-registered (NCT05553522), single-arm, multicenter, ongoing, phase 1 trial that aims to determine the safety and efficacy of TCT+SRS in HER2+ BCBM patients. Patients with age 18-80 years, ECOG score 0-2, normal organ function, and ≤10 newly-diagnosed BMs are being enrolled at six US centers. Any number of prior systemic therapies are allowed, except tucatinib and capecitabine. Key exclusion criteria include leptomeningeal metastases, intra-tumoral or peri-tumoral hemorrhage, and BMs ≤5 mm of optic chiasm/nerve. Primary endpoint is maximum tolerated dose (MTD) of tucatinib, in this 3 + 3 de-escalation study starting at dose level (DL) 300 mg BID. DL-1 is 250 mg BID, and DL-2 is 200 mg BID. Secondary endpoints include efficacy as determined by response rate, intracranial progression-free survival (PFS), extracranial PFS, and overall survival. Neurocognitive outcomes are assessed using Hopkins Verbal Learning, Controlled Oral Word Association, Trail Making, and Grooved Pegboard Tests. Toxicities are assessed using CTCAE v5.0. Quality of life is assessed using Functional Assessment of Cancer Therapy with Brain Tumor module. Patients are administered tucatinib with SRS as per treating radiation oncologist, followed by tucatinib for two weeks, i.e. dose-limiting toxicity (DLT) period, followed by TCT until progression or intolerable toxicity. DLTs are defined by Grade 3 or 4 thrombocytopenia, grade 4 anemia, grade 4 neutropenia lasting >7 days, febrile neutropenia, and any non-hematologic toxicity of grade ≥3 (excluding alopecia). Cohort expansion at MTD to 40 patients is planned. Patient enrollment started in February 2023 and remains ongoing.

CTNI-70. RESULTS FROM THE PHASE 1 AND PHASE 1 EXPANSION COHORTS OF SJ901: A PHASE 1/2 TRIAL OF SINGLE-AGENT MIRDAMETINIB (PD-0325901) IN CHILDREN, ADOLESCENTS, AND YOUNG ADULTS WITH LOW-GRADE GLIOMA

Abstract BACKGROUND Mirdametinib is an investigational, oral, selective MEK1/2 inhibitor (MEKi) with high blood-brain-barrier penetration. We hypothesized that mirdametinib would benefit patients with pediatric low-grade gliomas (pLGG) and launched SJ901 (NCT04923126) to determine the recommended Phase 2 dose (RP2D), safety, and efficacy. METHODS For Phase 1 and Phase 1 expansion patients were required to be ≥2 and <25 years-old, MEKi-naive, and have recurrent/progressive pLGG with biopsy-proven MAPK pathway activation (except BRAF V600). Three dose levels (DL1: 2 mg/m2/dose BID, DL2: 2.5mg/m2/dose BID, DL3: 3mg/m2/dose BID administered continuously in 28-day cycles) were evaluated with an expansion cohort to assess the highest tolerated dose level in a total of 12 patients. RP2D was defined as the dose causing ≤3 dose-limiting toxicities (DLTs) in 12 patients within the first cycle of therapy. RESULTS Between June 2021 and December 2023, 23 patients enrolled (DL1=5, DL2=6, and DL3=12). Median age was 8.4 years (2.5-21.9); 52% female. Alterations were seen in BRAF (n=12;52%), FGFR1 (n=5;22%), NF1 (n=3;13%), RAF1 (n=2;9%), and MYB (n=1;4%). The median follow-up time was 14.6 months (3.2-27.8). One DLT was observed (grade-3 thrombocytopenia). Seventeen (74%) patients completed or remain on-therapy; 4(17%) stopped for progression (2 FGFR1; 1 MYB; 1 BRAF); 2 discontinued for toxicities [1 grade-2 rash; 1 grade-4 creatine phosphokinase (CPK) elevation]. Dose modifying adverse events included weight gain, CPK elevations, and rash. No significant cardiac or retinal toxicity was observed. Twelve (63%) of 19 patients with measurable tumors achieved an objective response (1 major, 6 partial, 5 minor). The median time to ≥ minor response was 5.4 months (1.7-7.3). DL3 (3 mg/m2/dose BID) was declared the RP2D. CONCLUSIONS Mirdametinib is well-tolerated and has promising clinical activity in patients with recurrent/progressive pLGG. Phase 2 is ongoing to establish safety and efficacy in newly diagnosed, recurrent/refractory tumors, and in patients with prior MEKi exposure.

CTNI-49. PRECISION MEDICINE CLINICAL TRIAL FOR ADULT PATIENTS WITH RECURRENT GLIOBLASTOMA

Abstract Salvage therapies for recurrent glioblastoma (rGBM) have limited efficacy, with median overall survival of 9 months (OS-9) and 6-month progression-free survival (PFS-6) of 10-25%. Given GBM’s molecular heterogeneity, targeting a single molecular abnormality in isolation has consistently failed as a strategy, and precision combination approaches are needed. An initial 15-patient cohort evaluated the feasibility and safety of treating patients with rGBM with an individualized treatment regimen; we added a second 15-patient expansion cohort to improve the power of preliminary efficacy assessment. Patients underwent clinically indicated surgery with genomic profiling using the UCSF500 targeted DNA sequencing panel. Each personalized treatment regimen combined up to 4 FDA-approved drugs, including one cytotoxic agent, as determined by consensus discussion at an individualized molecular tumor board for each patient. Bevacizumab was not utilized in these combinations. The primary objective of the combined 30-patient cohort was efficacy of individualized treatment regimens by OS-9; secondary objectives included safety and additional efficacy measures including PFS-6. Median age was 53 years (range 32-71). Of 30 patients, 18 were male, 23 were enrolled at first recurrence, 29 had IDH-wildtype glioblastoma, 1 had IDH-mutant astrocytoma, and 10 had MGMT promoter methylation. A total of 12 FDA-approved drugs were used in 18 combinations; the most common regimen prescribed was lomustine, afatinib, and abemaciclib (7; 23%,); second-most common was temozolomide, olaparib, and afatinib (4; 13%). OS-9 of the combined cohort was 70% (95% CI 0.55 – 0.89) and PFS-6 was 27% (95% CI 0.15 – 0.48), with median OS of 11.6 months (95% CI 9.7 – 16.7) and median PFS of 3.7 months (95% CI 2.0 – 5.5).While overall efficacy was modest, implementation of individualized treatment regimens in a timely fashion was safe and feasible for patients with surgically resectable rGBM. Analysis is ongoing to assess whether specific genomic profiles or treatment regimens were particularly efficacious.

DNAR-10. PHASE I CLINICAL TRIAL OF PEPOSERTIB PLUS RADIOTHERAPY IN ADULTS WITH NEWLY-DIAGNOSED MGMT-UNMETHYLATED GLIOBLASTOMA

Abstract BACKGROUND DNA-dependent protein kinase (DNA-PK) is an attractive target in GBM because it promotes unwanted DNA repair and renders cancer cells less vulnerable to DNA damaging agents, such as radiotherapy (RT). Peposertib, a small molecule inhibitor of DNA-PK, has demonstrated pre-clinical efficacy in sensitizing GBM to RT, resulting in tumor regression. METHODS 21 patients with newly-diagnosed MGMT-unmethylated GBM received peposertib plus 6-weeks of RT to determine the maximum-tolerated dose (MTD) based on the Bayesian Optimal Interval design. The dose-limiting toxicity (DLT) period was 10-weeks. Patients received at least 6-cycles of adjuvant temozolomide (NCT04555577). Single-nuclei RNA-sequencing (snRNA-Seq) and spatial transcriptomics (Visium, 10x Genomics) were performed on matched pair primary-recurrent tumors and controls, incorporating tumor cell state and cell type definitions by automated cluster classification and differential expression of marker genes. RESULTS The MTD of peposertib in combination with RT was 300mg per RT fraction day. One DLT (G3 radiation necrosis @300mg) was observed. After a median follow-up of 15.4 months (interquartile-range 8.9-18.5), mPFS was 10.8 months (95%CI 8.33-NR) and mOS was 22.9 months (95%CI 16-NR). 6/21 (29%) patients have undergone re-resection to date. snRNA-Seq on 102,709 cells from 12 primary and 3 recurrent tumors revealed that pre-treatment tumor cell states were progenitor-like, while treatment with peposertib plus RT was associated with differentiated and inflammatory malignant cell states, along with macrophage infiltration. Spatial transcriptomics of 8 matched primary-recurrent tumors (20,793 transcriptomes) confirmed malignant cell differentiation and enrichment of pro-inflammatory macrophages after inhibition of DNA-PK. 5 patients will be enrolled into a window-of-opportunity expansion cohort to evaluate intratumoral drug concentration. CONCLUSION The combination of peposertib and intracranial RT was safe. Survival data for this MGMT-unmethylated GBM population was promising. Single nuclei and spatial transcriptomic analyses revealed enrichment of pro-inflammatory macrophages in the tumor microenvironmentafter DNA-PK inhibition. The study was supported by EMD-Serono (CrossRef Funder ID: 10.13039/100004755).

Phase I study of the tissue factor-targeting antibody-drug conjugate XB002 among patients with advanced solid tumors (JEWEL-101): Design of expansion cohorts for endometrial, epithelial ovarian, and cervical cancers

Phase I study of the tissue factor-targeting antibody-drug conjugate XB002 among patients with advanced solid tumors (JEWEL-101): Design of expansion cohorts for endometrial, epithelial ovarian, and cervical cancers

Neoadjuvant Treatment With Regorafenib and Capecitabine Combined With Radiotherapy in Locally Advanced Rectal Cancer: A Multicenter Phase Ib Trial (RECAP)–SAKK 41/16

BackgroundThe multi tyrosine kinase inhibitor regorafenib is active in metastatic colorectal cancer. Improvement in clinical outcome by adding regorafenib to long-course chemoradiotherapy (LcCRT) was investigated in molecularly undefined LARC. MethodsPatients with T3-4 and/or N+ but M0 rectal cancer were included. Neoadjuvant LcRCT consisted in capecitabine (C) 825mg/m2 d1-d38 and 28 fractions of 1.8Gy (50.4Gy). Regorafenib was added d1-14 and d22-35 in 3 dose escalation (DE) cohorts (40mg/80mg/120mg). The recommended dose (RD) was used for the expansion (EXP) cohort. Primary endpoints were dose-limiting toxicity (DLT) for DE and pathological response (near-complete regression [npCR] or complete regression [pCR]) for EXP. ResultsOverall, 25 patients were included. Two DLTs occurred at the regorafenib dose level of 120 mg, thereby establishing the RD at 80mg daily. Among the 19 patients who were treated at the RD, 8 (42.1%; 1-sided 80% confidence interval [CI] (lower bound): 30.7%; 95% CI, 20.3%-66.5%) reached the primary endpoint (5 [26.3%] had npCR and 3 [15.8%] pCR). One additional patient received no surgery due to clinical complete response. All patients had R0 resections and clear circumferential margins. Postoperative complications occurred in 6 patients (35.3%). The most common grade ≥ 3 treatment-related adverse event in the EXP cohort was diarrhea (2 patients). ConclusionAdding regorafenib 80 mg to LcCRT in LARC resulted in both primary endpoints being met and yielded an expectedpathological response rate. Toxicity was manageable, and postoperative complications were as expected.

503LBA LBA Orals: Results from CA240-0007, a phase 1/2 multiple expansion cohort study of BMS-986504 in patients (pts) with advanced solid tumors with homozygous MTAP deletion (MTAP-del)

503LBA LBA Orals: Results from CA240-0007, a phase 1/2 multiple expansion cohort study of BMS-986504 in patients (pts) with advanced solid tumors with homozygous MTAP deletion (MTAP-del)

235 (PB223): IND.243: a multiple expansion cohort, signal seeking and dose confirmation phase 2 trial of the PKMYT1 inhibitor lunresertib

235 (PB223): IND.243: a multiple expansion cohort, signal seeking and dose confirmation phase 2 trial of the PKMYT1 inhibitor lunresertib

A Phase II Study Assessing Long-term Response to Ibrutinib Monotherapy in Recurrent or Refractory CNS Lymphoma.

Ibrutinib is a first-in-class inhibitor of Bruton tyrosine kinase. We previously reported the safety and short-term antitumor activity of ibrutinib in 20 patients with relapsed or refractory (r/r) primary central nervous system (CNS) lymphoma (PCNSL) or secondary CNS lymphoma (SCNSL). We enrolled 26 additional patients with r/r PCNSL/SCNSL into the dose-expansion cohort of the trial into a combined cohort of 46 patients (31 with PCNSL and 15 with SCNSL). Patients received ibrutinib at 560 or 840 mg daily in the dose-escalation cohort and ibrutinib at 840 mg daily in the expansion cohort. The median follow-up was 49.9 and 62.1 months for patients with PCNSL and SCNSL, respectively. We sequenced DNA from available tumor biopsies and cerebrospinal fluid collected before and during ibrutinib therapy. Tumor responses were observed in 23/31 (74%) patients with PCNSL and 9/15 (60%) patients with SCNSL, including 12 complete responses in PCNSL and 7 in SCNSL. The median progression-free survival (PFS) for PCNSL was 4.5 months [95% confidence interval (CI), 2.8-9.2] with 1-year PFS at 23.7% (95% CI, 12.4%-45.1%). The median duration of response in the 23 PCNSL responders was 5.5 months. The median PFS in SCNSL was 5.3 months (95% CI, 1.3-14.5) with a median duration of response of 8.7 months for the 9 responders. Exploratory biomarker analysis suggests that mutations in TBL1XR1 may be associated with a long-term response to ibrutinib in PCNSL (P = 0.0075). Clearance of ctDNA from cerebrospinal fluid was associated with complete and long-term ibrutinib responses. Our study confirms single-agent activity of ibrutinib in r/r CNS lymphoma and identifies molecular determinants of response based on long-term follow-up.

A multicenter, randomized, non-comparative, phase II study of nivolumab ± ipilimumab for patients with metastatic sarcoma (Alliance A091401): expansion cohorts and correlative analyses

BackgroundIn this open-label, randomized, non-comparative, multicenter phase II study (Alliance A091401) we report on three expansion cohorts treated with nivolumab (N) with and without ipilimumab (N+I) and provide a multi-omic...

620P Efficacy, safety and PKPD of 23ME-00610, a first-in-class anti-CD200R1 antibody, in patients with tumor mutational burden-high (TMB-H) and/or microsatellite instability-high (MSI-H) cancers: Results from an expansion cohort

620P Efficacy, safety and PKPD of 23ME-00610, a first-in-class anti-CD200R1 antibody, in patients with tumor mutational burden-high (TMB-H) and/or microsatellite instability-high (MSI-H) cancers: Results from an expansion cohort

1706P Efficacy, safety and PKPD of 23ME-00610, a first-in-class anti-CD200R1 antibody, in patients with advanced or metastatic clear-cell renal cell carcinoma (ccRCC): Results from a multi-center multi-country phase I/IIa expansion cohort

1706P Efficacy, safety and PKPD of 23ME-00610, a first-in-class anti-CD200R1 antibody, in patients with advanced or metastatic clear-cell renal cell carcinoma (ccRCC): Results from a multi-center multi-country phase I/IIa expansion cohort

762P First results from phase II dose expansion cohort of transcon IL-2 β/γ in combination with standard of care chemotherapy for platinum resistant ovarian cancer (PROC) in the IL Believe trial

762P First results from phase II dose expansion cohort of transcon IL-2 β/γ in combination with standard of care chemotherapy for platinum resistant ovarian cancer (PROC) in the IL Believe trial

A Phase I Open-Label Study of Cediranib Plus Etoposide and Cisplatin as First-Line Therapy for Patients With Extensive-Stage Small-Cell Lung Cancer or Metastatic Neuroendocrine Non–Small-Cell Lung Cancer

IntroductionSmall cell lung cancer (SCLC) is known to express high levels of the proangiogenic factor vascular endothelial growth factor (VEGF). We assessed the safety and tolerability of cediranib, an oral inhibitor of VEGF receptor tyrosine kinases, in combination with etoposide and cisplatin as first-line therapy for extensive-stage (ES) SCLC or metastatic lung neuroendocrine cancer (NEC). MethodsPatients received up to six 21-day cycles of etoposide (100 mg/m2, days 1-3) and cisplatin (80 mg/m2, day 1) with once-daily cediranib until disease progression or unacceptable toxicity. Cediranib dosing started at 30 mg with de-escalation cohorts planned based on cycle 1 dose-limiting toxicities (DLTs). An expansion cohort of 12 patients was enrolled at the recommended phase II dose. ResultsTwenty-two patients (18 with ES SCLC, 4 with NEC) received treatment. Only 4 patients were enrolled at the 30 mg cediranib dose before other studies established 20 mg/day as the recommended dose with chemotherapy. Among the 18 patients enrolled at the 20-mg dose, common adverse events included nausea/vomiting, neutropenia, and diarrhea; 8 patients (44%) had grade 1 or 2 hypertension, and 2 (11%) had grade 3 hemoptysis. For all 18 patients, the objective response rate and median progression-free survival duration were 67% and 7.9 months. Plasma levels of VEGF were significantly higher, and those of soluble VEGFR2 were significantly lower, on day 22 than at baseline but were not correlated with tumor shrinkage. ConclusionsCediranib (20 mg) plus etoposide and cisplatin is well tolerated and has promising clinical activity.

1598P Xaluritamig, a STEAP1 x CD3 XmAb 2+1 immune therapy, in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC): Initial results from dose expansion cohorts in a phase I study

1598P Xaluritamig, a STEAP1 x CD3 XmAb 2+1 immune therapy, in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC): Initial results from dose expansion cohorts in a phase I study

Efficacy and safety of bintrafusp alfa in 2 phase I expansion cohorts with advanced HCC.

Simultaneous inhibition of the TGF-β and programmed cell death 1 ligand 1 pathways provides a potential novel treatment approach. Bintrafusp alfa, a first-in-class bifunctional fusion protein composed of the extracellular domain of TGF-βRII (a TGF-β "trap") fused to a human IgG1 monoclonal antibody blocking programmed cell death 1 ligand 1, was evaluated in patients with advanced HCC. In this global, open-label, phase I study (NCT02517398), patients with programmed cell death 1 ligand 1-unselected HCC who failed or were intolerant to ≥1 line of sorafenib received bintrafusp alfa 1200mg every 2 weeks in a dose-escalation (n = 38) or dose-expansion (n = 68) cohort until confirmed progression, unacceptable toxicity, or trial withdrawal. The primary endpoint was the best overall response per Response Evaluation Criteria in Solid Tumors version 1.1 by an independent review committee. Secondary endpoints included investigator-assessed best overall response, safety, and pharmacokinetics. Median follow-up times (range) were 41.4 (39.8-44.2) and 38.6 (33.5-39.7) months in the dose-escalation and dose-expansion cohorts, respectively. The objective response rate was below the prespecified 20% objective response rate threshold set to evaluate the efficacy of bintrafusp alfa in both cohorts (10.5% and 8.8%, respectively). Median overall survival and progression-free survival, respectively, were 13.8 and 1.5 months in the dose-escalation cohort and 13.5 and 1.4 months in the dose-expansion cohort. Treatment-related adverse events occurred in 78.9% and 64.7% of patients in the respective cohorts (grade ≥3 in 18.4% and 25.0% of patients). Bintrafusp alfa showed moderate clinical activity and a safety profile consistent with previous studies of bintrafusp alfa in patients with advanced HCC.

A single-arm, exploratory study of disitamab vedotin (DV) combined with camrelizumab and platinum-based chemotherapy as first-line treatment in patients with HER2 expressing locally advanced or metastatic esophageal squamous cell carcinoma (ESCC).

TPS217 Background: Esophageal cancer (EC) is one of the most common cancers worldwide with esophageal squamous cell carcinoma (ESCC) being the predominant histological subtype. PD-1 blockades combined with chemotherapy are now standard-of-care in first-line setting for patients with ESCC. HER2 expression, prevalent in an estimated 7.6% to 28.5% of ESCC cases, correlates with diminished overall survival, suggesting HER2-targeted therapy as a potential novel approach. To our knowledge, there is currently no clinical trial regarding anti-HER2 therapy in ESCC. Clinical evidence has suggested the potential synergistic anti-tumor effect of Disitamab Vedotin (DV) with PD-1 inhibitors in HER2-expressing gastric or gastroesophageal junction (G/GEJ) cancers. This single-arm, exploratory study aimed to evaluate the safety and preliminary anti-tumor activity of DV combined with camrelizumab and platinum-based chemotherapy in ESCC. Methods: This is a single-arm, exploratory study (NCT06055153). Approximately 20 patients will be enrolled in this study, phase 1 will initiate with a 3+3 dose-escalation scheme (2.5mg/kg to 2.0mg/kg) to identify dose-limiting toxicities (DLTs) and establish a safe dosage of DV. The expansion cohort will subsequently evaluate this dose for both efficacy and safety. The study population will included both male and female patients over the age of 18 with histologically confirmed ESCC, and locally advanced unresectable, recurrent unresectable or metastatic EC verified by imaging examination. This group also includes those patients who have experienced relapse or progression more than six months post the conclusion of last therapeutic regimen. Required HER2 expression levels in tumor specimens range from IHC 1+ to 3+. According to RECIST v1.1, participants must have at least one measurable lesion, an ECOG performance status of 0 or 1, and a minimum expected survival of 12 weeks with suitable organ function. Treatment protocol includes intravenous administration of DV (either 2.5 mg/kg or 2.0 mg/kg on day 1), Camrelizumab (200 mg on day 1), and Cisplatin (75mg/m2) or Nedaplatin (75mg/m2) on a 21-day cycle, continued until disease progression or the advent of unacceptable toxicity. The primary outcomes for evaluation are DLT for safety and the objective response rate (ORR) for efficacy. Adverse events will be monitored in accordance with the CTCAE 5.0 criteria. Secondary endpoints encompass progression-free survival (PFS), overall survival (OS), disease control rate (DCR), duration of response (DoR), and time to response (TTR). Clinical trial information: NCT06055153 .

A phase Ib/II study of pacritinib, an interleukin 1 receptor associated kinase 1 (IRAK1) inhibitor, in patients (pts) with solid tumors harboring the 1q21.3 copy number amplification (CNA).

43 Background: The role of IRAK1 pathway in inflammatory and immune response is established in autoimmune diseases but less well-understood in cancer. Chromosome 1q21.3 CNA detected in plasma cell-free DNA was observed in pts with advanced solid tumors, and associated with IRAK1 upregulation. In preclinical animal models, IRAK1 upregulation promoted tumorigenesis, while its inhibition led to decreased tumor growth. Pacritinib is a JAK2/FLT3 inhibitor that is FDA approved for treatment in myelofibrosis, but also have known activity against IRAK1. We hypothesize that pacritinib may be effective in disease control of pts with plasma 1q21.3 CNA. Methods: A phase Ib/II clinical trial was designed to investigate the efficacy of pacritinib in pts with treatment (rx) refractory solid tumors harboring 1q21.3 CNA. Serial pt tumor and blood samples were collected and analyzed to elucidate the effect of IRAK1 inhibition on tumor microenvironment and systemic immune modulation. Results: 330 patients were screened, 1q21.3 CNA was detected in 30.1% of pts. Highest incidence of 1q21.3 CNA positivity was detected in breast cancer (39.8%), colorectal cancer (39.7%) and lung cancer (36.1%). 12 pts were commenced on rx over 3 dose levels (DL) (DL1: n=6, DL2: n=3, DL3: n=3). At DL1 (200mg BID), no DLTs were observed, but 2 pts had G3 transaminitis attributed to drug/disease, and 1 pt had intolerable G2 rash; decision was made for dose reduction. At DL2 (200mg OM, 100mg ON), no DLTs were observed. Reescalation to 200mg BID (DL3) was carried out with no DLT observed. Pacritinib at 200mg BD was declared the recommended phase II dose in pts with solid tumors. In the dose expansion cohort, 8 pts (4 colorectal cancer, 3 hepatobiliary [HPB] cancer, 1 lung cancer) have been enrolled thus far. No objective responses were observed. Within pts with HPB tumors, 1 pt with pancreatic cancer had a progression-free survival (PFS) of 25.0 weeks, and 1 pt with cholangiocarcinoma had a PFS of 15.9 weeks. Preliminary analysis of serial tumor biopsy samples suggest an expansion of CD8+ T cell population with pacritinib rx. Serial peripheral blood mononuclear cells analysis showed no significant trend in change in CD8+ T cell population, but a predominance of PD-1+ T cells with rx, and also an increase in CD4+ T cell population. In the myeloid cell population, there appears to be decrease in dendritic cell population, but no significant change in trend of macrophage was observed. Conclusions: Pacritinib at 200mg BID is safe and tolerable in pts with solid tumors. IRAK1 inhibition appears to modulate immune cell populations both in the tumor microenvironment and systemic circulation. Dose expansion is underway, with potential signal of disease control in HPB tumors. Clinical trial information: NCT04520269 .

Anti-CD7 allogeneic WU-CART-007 in patients with relapsed/refractory T-cell acute lymphoblastic leukemia/lymphoma: a phase 1/2 trial.

Relapsed/refractory T-cell acute lymphoblastic leukemia (ALL)/lymphoma (LBL) represent a significant unmet medical need. WU-CART-007 is a CD7-targeting, allogeneic, fratricide-resistant chimeric antigen receptor T cell product generated from healthy donor T cells. WU-CART-007 was evaluated in a phase 1/2 study with a 3 + 3 dose-escalation design followed by cohort expansion in relapsed/refractory T-ALL/LBL. Patients received one infusion of WU-CART-007 after standard or enhanced lymphodepleting chemotherapy. The primary objectives, to characterize safety and assess the composite complete remission rate, were met. Of 26 patients enrolled, 13 received the recommended phase 2 dose (RP2D) of 900 million cells of WU-CART-007 with enhanced lymphodepletion. The most common treatment-related adverse event was cytokine release syndrome (88.5%; 19.2% grade 3-4). Biochemical abnormalities consistent with grade 2 hemophagocytic lymphohistiocytosis were seen in one patient (3.8%). Grade 1 immune effector cell-associated neurotoxicity syndrome events (7.7%) and one grade 2 acute graft-vs-host disease event occurred. Grade 5 events (11.5%) were due to fungal infection and multi-organ failure. The composite complete remission rate was 81.8% among 11/13 patients evaluable for response at the RP2D. WU-CART-007 at the RP2D demonstrated a high response rate in patients with relapsed/refractory T-ALL/LBL and has the potential to provide a new treatment option. ClinicalTrials.gov registration: NCT04984356.