Lenvatinib plus pembrolizumab versus lenvatinib plus placebo for advanced hepatocellular carcinoma (LEAP-002): a randomised, double-blind, phase 3 trial.

BACKGROUND: Systemic therapies have improved the management of hepatocellular carcinoma, but there is still a need to further enhance overall survival in first-line advanced stages. This study aimed to evaluate the addition of pembrolizumab to lenvatinib versus lenvatinib plus placebo in the first-line setting for unresectable hepatocellular carcinoma. METHODS: In this global, randomised, double-blind, phase 3 study (LEAP-002), patients aged 18 years or older with unresectable hepatocellular carcinoma, Child Pugh class A liver disease, an Eastern Cooperative Oncology Group performance status of 0 or 1, and no previous systemic treatment were enrolled at 172 global sites. Patients were randomly assigned (1:1) with a central interactive voice-response system (block size of 4) to receive lenvatinib (bodyweight <60 kg, 8 mg/day; bodyweight ≥60 kg, 12 mg/day) plus pembrolizumab (200 mg every 3 weeks) or lenvatinib plus placebo. Randomisation was stratified by geographical region, macrovascular portal vein invasion or extrahepatic spread or both, α-fetoprotein concentration, and Eastern Cooperative Oncology Group performance status. Dual primary endpoints were overall survival (superiority threshold at final overall survival analysis, one-sided p=0·019; final analysis to occur after 532 events) and progression-free survival (superiority threshold one-sided p=0·002; final analysis to occur after 571 events) in the intention-to-treat population. Results from the final analysis are reported. This study is registered with ClinicalTrials.gov, NCT03713593, and is active but not recruiting. FINDINGS: Between Jan 17, 2019, and April 28, 2020, of 1309 patients assessed, 794 were randomly assigned to lenvatinib plus pembrolizumab (n=395) or lenvatinib plus placebo (n=399). Median age was 66·0 years (IQR 57·0-72·0), 644 (81%) of 794 were male, 150 (19%) were female, 345 (43%) were Asian, 345 (43%) were White, 22 (3%) were multiple races, 21 (3%) were American Indian or Alaska Native, 21 (3%) were Native Hawaiian or other Pacific Islander, 13 (2%) were Black or African American, and 46 (6%) did not have available race data. Median follow up as of data cutoff for the final analysis (June 21, 2022) was 32·1 months (IQR 29·4-35·3). Median overall survival was 21·2 months (95% CI 19·0-23·6; 252 [64%] of 395 died) with lenvatinib plus pembrolizumab versus 19·0 months (17·2-21·7; 282 [71%] of 399 died) with lenvatinib plus placebo (hazard ratio [HR] 0·84; 95% CI 0·71-1·00; stratified log-rank p=0·023). As of data cutoff for the progression-free survival final analysis (April 5, 2021), median progression-free survival was 8·2 months (95% CI 6·4-8·4; 270 events occurred [42 deaths; 228 progressions]) with lenvatinib plus pembrolizumab versus 8·0 months (6·3-8·2; 301 events occurred [36 deaths; 265 progressions]) with lenvatinib plus placebo (HR 0·87; 95% CI 0·73-1·02; stratified log-rank p=0·047). The most common treatment-related grade 3-4 adverse events were hypertension (69 [17%] of 395 patients in the lenvatinib plus pembrolizumab group vs 68 [17%] of 395 patients) in the lenvatinib plus placebo group), increased aspartate aminotransferase (27 [7%] vs 17 [4%]), and diarrhoea (25 [6%] vs 15 [4%]). Treatment-related deaths occurred in four (1%) patients in the lenvatinib plus pembrolizumab group (due to gastrointestinal haemorrhage and hepatorenal syndrome [n=1 each] and hepatic encephalopathy [n=2]) and in three (1%) patients in the lenvatinib plus placebo group (due to gastrointestinal haemorrhage, hepatorenal syndrome, and cerebrovascular accident [n=1 each]). INTERPRETATION: In earlier studies, the addition of pembrolizumab to lenvatinib as first-line therapy for advanced hepatocellular carcinoma has shown promising clinical activity; however, lenvatinib plus pembrolizumab did not meet prespecified significance for improved overall survival and progression-free survival versus lenvatinib plus placebo. Our findings do not support a change in clinical practice. FUNDING: Eisai US, and Merck Sharp & Dohme, a subsidiary of Merck.

A TCR-mimic antibody to WT1 bypasses tyrosine kinase inhibitor resistance in human BCR-ABL+ leukemias.

Acute and chronic leukemias, including CD34(+) CML cells, demonstrate increased expression of the Wilms tumor gene 1 product (WT1), making WT1 an attractive therapeutic target. However, WT1 is a currently undruggable, intracellular protein. ESKM is a human IgG1 T-cell receptor mimic monoclonal antibody directed to a 9-amino acid sequence of WT1 in the context of cell surface HLA-A*02. ESKM was therapeutically effective, alone and in combination with tyrosine kinase inhibitors (TKIs), against Philadelphia chromosome-positive acute leukemia in murine models, including a leukemia with the most common, pan-TKI, gatekeeper resistance mutation, T315I. ESKM was superior to the first-generation TKI, imatinib. Combination therapy with ESKM and TKIs was superior to either drug alone, capable of curing mice. ESKM showed no toxicity to human HLA-A*02:01(+) stem cells under the conditions of this murine model. These features of ESKM make it a promising nontoxic therapeutic agent for sensitive and resistant Ph(+) leukemias.

Analysis of pediatric autologous PBSC apheresis and transplant: age is a major factor affecting post-transplant toxicity.

BACKGROUND: High-dose chemotherapy followed by autologous hematopoietic cell transplantation (HCT) is used in many therapeutic protocols for pediatric intra- and extra-cranial solid tumors. HCT can be curative, but is associated with significant toxicity. PROCEDURE: Between January 2001 and June 2009, 92 solid tumor patients (age 6 months to 27 years) underwent 94 autologous apheresis procedures at Children's National Medical Center. Out of that group, 71 patients, who underwent 162 autologous HCT, were analyzed for transplant outcomes. Multiple variable modeling was used to identify independent variables related to transplant toxicity outcome measures, such as bacteremia, intensive care admission, and death. Other outcome measures (time to pre-apheresis peripheral blood CD34+ count, product yield, and time to engraftment) were also analyzed. Independent variables included patient-specific variables (age, weight, tumor type, chemotherapy administered, and primary vs. relapsed disease) and harvest or transplant-related variables (total white blood cell and CD34+ cell counts prior to transplant, and quantity of total nucleated cells and CD34+ cells infused during transplant). RESULTS: Transplant toxicity was significantly greater in younger patients (P = 0.001) and in neuroblastoma patients (P = 0.003). The time to neutrophil engraftment, controlling for weight, age, and chemotherapy, was positively related to absolute CD34+ cells/kg infused (P = 0.01). The time to CD34+ recovery pre-apheresis was affected by patient diagnosis (P = 0.05). CONCLUSIONS: Younger patients had increased transplant toxicity, with infants <1 year of age at highest risk for fever, bacteremia, admission to intensive care, and death. Infants would likely benefit from hospitalization after autologous HCT until neutrophil recovery.

Randomized Phase 3 LEAP-012 Study: Transarterial Chemoembolization With or Without Lenvatinib Plus Pembrolizumab for Intermediate-Stage Hepatocellular Carcinoma Not Amenable to Curative Treatment.

PURPOSE: Transarterial chemoembolization (TACE) is the standard of care for patients with intermediate-stage hepatocellular carcinoma (HCC). Lenvatinib, a multikinase inhibitor, and pembrolizumab, a PD-1 inhibitor, have shown efficacy and tolerability in patients with HCC, and adding this combination to TACE may enhance clinical benefit. PROTOCOL: LEAP-012 is a prospective, double-blind randomized phase 3 study. Adults with confirmed HCC localized to the liver without portal vein thrombosis and not amenable to curative treatment, ≥ 1 measurable tumor per Response Evaluation Criteria in Solid Tumors 1.1 (RECIST 1.1), Eastern Cooperative Oncology Group performance status 0 or 1, Child-Pugh class A and no previous systemic treatment for HCC are eligible. Patients will be randomly assigned to lenvatinib once daily plus pembrolizumab every 6 weeks plus TACE or placebos plus TACE. Dual primary endpoints are overall survival and progression-free survival per RECIST 1.1 by blinded independent central review (BICR). Secondary endpoints are progression-free survival, objective response rate, disease control rate, duration of response and time to progression per modified RECIST by BICR; objective response rate, disease control rate, duration of response and time to progression per RECIST 1.1 by BICR; and safety. STATISTICS: The planned sample size, 950 patients, was calculated to permit accumulation of sufficient overall survival events in 5 years to achieve 90% power for the overall survival primary endpoint. DISCUSSION: LEAP-012 will evaluate the clinical benefit of adding lenvatinib plus pembrolizumab to TACE in patients with intermediate-stage HCC not amenable to curative treatment. CLINICALTRIALS: gov NCT04246177.

CD34⁺ collection efficiency as a function of blood volumes processed in pediatric autologous peripheral blood stem cell collection.

PURPOSE: To characterize the relationship between CD34(+) collection efficiency and blood volumes processed in pediatric patients undergoing autologous peripheral blood stem cell (PBSC) collection. METHODS: Retrospective 8-year (2001-2009) study of pediatric patients (n = 79) with neuroblastoma and central nervous system (CNS) tumors undergoing first day of autologous PBSC harvest using MNC program on the COBE Spectra (Caridian BCT, Lakewood, CO) was performed. Patients undergoing 0 to 2.9 BV (standard volume), 3 to 6 BV (large volume), and greater than 6 BV (ultra large volume) harvests were evaluated for CD34(+) collection efficiency, diagnosis (neuroblastoma vs. nonneuroblastoma), disease type (primary vs. relapse), mobilization regimen, granulocyte colony stimulating factor (GCSF) dose, and apheresis complications. RESULTS: CD34(+) collection efficiencies (CE) for neuroblastoma patients were 67%, 50%, and 53% for standard (n = 14), large (n = 9), and ultra large (n = 5) volume harvests, respectively. Similarly, patients with nonneuroblastoma diagnoses had CD34(+) CE of 63%, 55%, and 65% for low (n = 19), large (n = 27), and ultra large (n = 5) volume harvests, respectively. Weight, granulocyte colony stimulating factor (G-CSF) stimulation, type of mobilization, and apheresis complications (normalized by run time) were similar between the standard, large, and ultra large volume groups in patients with either neuroblastoma or nonneuroblastoma diagnoses. CONCLUSIONS: CD34(+) collection efficiency in pediatric autologous PBSC collection on the first day of harvest does not decrease with higher numbers of blood volumes processed in patients with either neuroblastoma or nonneuroblastoma primary disease. These results indirectly indicate bone marrow CD34(+) cell mobilization occurs with longer apheresis procedures in pediatric patients.

Phase Ib Study of Lenvatinib Plus Pembrolizumab in Patients With Unresectable Hepatocellular Carcinoma.

PURPOSE: The immunomodulatory effect of lenvatinib (a multikinase inhibitor) on tumor microenvironments may contribute to antitumor activity when combined with programmed death receptor-1 (PD-1) signaling inhibitors in hepatocellular carcinoma (HCC). We report results from a phase Ib study of lenvatinib plus pembrolizumab (an anti-PD-1 antibody) in unresectable HCC (uHCC). PATIENTS AND METHODS: In this open-label multicenter study, patients with uHCC received lenvatinib (bodyweight ≥ 60 kg, 12 mg; < 60 kg, 8 mg) orally daily and pembrolizumab 200 mg intravenously on day 1 of a 21-day cycle. The study included a dose-limiting toxicity (DLT) phase and an expansion phase (first-line patients). Primary objectives were safety/tolerability (DLT phase), and objective response rate (ORR) and duration of response (DOR) by modified RECIST (mRECIST) and RECIST version 1.1 (v1.1) per independent imaging review (IIR; expansion phase). RESULTS: A total of 104 patients were enrolled. No DLTs were reported (n = 6) in the DLT phase; 100 patients (expansion phase; included n = 2 from DLT phase) had received no prior systemic therapy and had Barcelona Clinic Liver Cancer stage B (n = 29) or C disease (n = 71). At data cutoff, 37% of patients remained on treatment. Median duration of follow-up was 10.6 months (95% CI, 9.2 to 11.5 months). Confirmed ORRs by IIR were 46.0% (95% CI, 36.0% to 56.3%) per mRECIST and 36.0% (95% CI, 26.6% to 46.2%) per RECIST v1.1. Median DORs by IIR were 8.6 months (95% CI, 6.9 months to not estimable [NE]) per mRECIST and 12.6 months (95% CI, 6.9 months to NE) per RECIST v1.1. Median progression-free survival by IIR was 9.3 months per mRECIST and 8.6 months per RECIST v1.1. Median overall survival was 22 months. Grade ≥ 3 treatment-related adverse events occurred in 67% (grade 5, 3%) of patients. No new safety signals were identified. CONCLUSION: Lenvatinib plus pembrolizumab has promising antitumor activity in uHCC. Toxicities were manageable, with no unexpected safety signals.

A therapeutic T cell receptor mimic antibody targets tumor-associated PRAME peptide/HLA-I antigens.

Preferentially expressed antigen in melanoma (PRAME) is a cancer-testis antigen that is expressed in many cancers and leukemias. In healthy tissue, PRAME expression is limited to the testes and ovaries, making it a highly attractive cancer target. PRAME is an intracellular protein that cannot currently be drugged. After proteasomal processing, the PRAME300-309 peptide ALYVDSLFFL (ALY) is presented in the context of human leukocyte antigen HLA-A*02:01 molecules for recognition by the T cell receptor (TCR) of cytotoxic T cells. Here, we have described Pr20, a TCR mimic (TCRm) human IgG1 antibody that recognizes the cell-surface ALY peptide/HLA-A2 complex. Pr20 is an immunological tool and potential therapeutic agent. Pr20 bound to PRAME+HLA-A2+ cancers. An afucosylated Fc form (Pr20M) directed antibody-dependent cellular cytotoxicity against PRAME+HLA-A2+ leukemia cells and was therapeutically effective against mouse xenograft models of human leukemia. In some tumors, Pr20 binding markedly increased upon IFN-γ treatment, mediated by induction of the immunoproteasome catalytic subunit ß5i. The immunoproteasome reduced internal destructive cleavages within the ALY epitope compared with the constitutive proteasome. The data provide rationale for developing TCRm antibodies as therapeutic agents for cancer, offer mechanistic insight on proteasomal regulation of tumor-associated peptide/HLA antigen complexes, and yield possible therapeutic solutions to target antigens with ultra-low surface presentation.

Mechanisms of leukemia resistance to antibody dependent cellular cytotoxicity.

Specific immunotherapy for acute leukemia remains a great unmet need. Native unmodified monoclonal antibody therapies, while promising, are inadequately effective for these malignancies, and multiple mechanisms for failure have been described. Antibody-dependent cellular cytotoxicity or phagocytosis is the primary modality of mAb-mediated cell killing in vivo, but ultimately leads to relapse of the leukemias, in model systems and in humans. By use of a T-cell receptor mimic mAb ESKM, derived against a WT1 peptide expressed in complex with HLA-A*02:01, whose only mechanism of therapeutic action is ADCC, we evaluated the mechanisms of leukemic relapse from its potent therapeutic action in mouse xenograft models of human leukemia. Leukemia escape was not associated with loss of the antigenic target, downregulation of cell surface HLA, antibody pharmacokinetic or biodistribution issues, or development of leukemia cell-intrinsic resistance to ADCC. Interestingly, the rapidity of leukemic growth determined whether leukemia was able to evade cytotoxicity independent of the presence of sufficient effector cells. By engineering leukemia cells with upregulated p27Kip1 and slower cell cycling times, we show that relapse was inversely correlated with growth rates resulting in the eventual inadequacy of effector to target ratio. Moreover, lack of migration of effector cells into lymphomatous pockets of ALL also allowed local escape. Successful leukemia therapy with mAb might therefore be improved in similar situations by combination with measures to reduce burden and slow leukemia cell growth.

T cell receptor mimic antibodies for cancer therapy.

The major hurdle to the creation of cancer-specific monoclonal antibodies (mAb) exhibiting limited cross-reactivity with healthy human cells is the paucity of known tumor-specific or mutated protein epitopes expressed on the cancer cell surface. Mutated and overexpressed oncoproteins are typically cytoplasmic or nuclear. Cells can present peptides from these distinguishing proteins on their cell surface in the context of human leukocyte antigen (HLA). T cell receptor mimic (TCRm) mAb can be discovered that react specifically to these complexes, allowing for selective targeting of cancer cells. The state-of-the-art for TCRm and the challenges and opportunities are discussed. Several such TCRm are moving toward clinical trials now.

Sequence context modulates the stability of a GxxxG-mediated transmembrane helix-helix dimer.

To quantify the relationship between sequence and transmembrane dimer stability, a systematic mutagenesis and thermodynamic study of the protein-protein interaction residues in the glycophorin A transmembrane helix-helix dimer was carried out. The results demonstrate that the glycophorin A transmembrane sequence dimerizes when its GxxxG motif is abolished by mutation to large aliphatic residues, suggesting that the sequence encodes an intrinsic propensity to self-associate independent of a GxxxG motif. In the presence of an intact GxxxG motif, the glycophorin A dimer stability can be modulated over a span of -0.5 kcal mol(-1) to +3.2 kcal mol(-1) by mutating the surrounding sequence context. Thus, these flanking residues play an active role in determining the transmembrane dimer stability. To assess the structural consequences of the thermodynamic effects of mutations, molecular models of mutant transmembrane domains were constructed, and a structure-based parameterization of the free energy change due to mutation was carried out. The changes in association free energy for glycophorin A mutants can be explained primarily by changes in packing interactions at the protein-protein interface. The energy cost of removing favorable van der Waals interactions was found to be 0.039 kcal mol(-1) per A2 of favorable occluded surface area. The value corresponds well with estimates for mutations in bacteriorhodopsin as well as for those mutations in the interiors of soluble proteins that create packing defects.

Therapeutic bispecific T-cell engager antibody targeting the intracellular oncoprotein WT1.

Intracellular tumor antigens presented on the cell surface in the context of human leukocyte antigen (HLA) molecules have been targeted by T cell-based therapies, but there has been little progress in developing small-molecule drugs or antibodies directed to these antigens. Here we describe a bispecific T-cell engager (BiTE) antibody derived from a T-cell receptor (TCR)-mimic monoclonal antibody (mAb) ESK1, which binds a peptide derived from the intracellular oncoprotein WT1 presented on HLA-A*02:01. Despite the very low density of the complexes at the cell surface, ESK1-BiTE selectively activated and induced proliferation of cytolytic human T cells that killed cells from multiple leukemias and solid tumors in vitro and in mice. We also discovered that in an autologous in vitro setting, ESK1-BiTE induced a robust secondary CD8 T-cell response specific for tumor-associated antigens other than WT1. Our study provides an approach that targets tumor-specific intracellular antigens without using cell therapy and suggests that epitope spreading could contribute to the therapeutic efficacy of this BiTE.

Therapeutic efficacy of an Fc-enhanced TCR-like antibody to the intracellular WT1 oncoprotein.

PURPOSE: RMFPNAPYL (RMF), a Wilms' tumor gene 1 (WT1)-derived CD8 T-cell epitope presented by HLA-A*02:01, is a validated target for T-cell-based immunotherapy. We previously reported ESK1, a high avidity (Kd < 0.2 nmol/L), fully-human monoclonal antibody (mAb) specific for the WT1 RMF peptide/HLA-A*02:01 complex, which selectively bound and killed WT1(+) and HLA-A*02:01(+) leukemia and solid tumor cell lines. EXPERIMENTAL DESIGN: We engineered a second-generation mAb, ESKM, to have enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) function due to altered Fc glycosylation. ESKM was compared with native ESK1 in binding assays, in vitro ADCC assays, and mesothelioma and leukemia therapeutic models and pharmacokinetic studies in mice. ESKM toxicity was assessed in HLA-A*02:01(+) transgenic mice. RESULTS: ESK antibodies mediated ADCC against hematopoietic and solid tumor cells at concentrations below 1 µg/mL, but ESKM was about 5- to 10-fold more potent in vitro against multiple cancer cell lines. ESKM was more potent in vivo against JMN mesothelioma, and effective against SET2 AML and fresh ALL xenografts. ESKM had a shortened half-life (4.9 days vs. 6.5 days), but an identical biodistribution pattern in C57BL/6J mice. At therapeutic doses of ESKM, there was no difference in half-life or biodistribution in HLA-A*02:01(+) transgenic mice compared with the parent strain. Importantly, therapeutic doses of ESKM in these mice caused no depletion of total WBCs or hematopoetic stem cells, or pathologic tissue damage. CONCLUSIONS: The data provide proof of concept that an Fc-enhanced mAb can improve efficacy against a low-density, tumor-specific, peptide/MHC target, and support further development of this mAb against an important intracellular oncogenic protein.