Modified FOLFOX6 plus bevacizumab with and without nivolumab for first-line treatment of metastatic colorectal cancer: phase 2 results from the CheckMate 9X8 randomized clinical trial.

BACKGROUND: Standard first-line therapies for metastatic colorectal cancer (mCRC) include fluoropyrimidine-containing regimens with oxaliplatin and/or irinotecan and a biologic agent. Immunotherapy may enhance antitumor activity in combination with standard therapies in patients with mCRC. Here, we present phase 2 results of nivolumab plus standard-of-care therapy (SOC; 5-fluorouracil/leucovorin/oxaliplatin/bevacizumab) versus SOC in the first-line treatment of patients with mCRC (CheckMate 9X8). METHODS: CheckMate 9X8 was a multicenter, open-label, randomized, phase 2/3 trial. Eligible patients were at least 18 years of age with unresectable mCRC and no prior chemotherapy for metastatic disease. Patients were randomized 2:1 to receive nivolumab 240 mg plus SOC or SOC alone every 2 weeks. The primary endpoint was progression-free survival (PFS) by blinded independent central review (BICR) per Response Evaluation Criteria in Solid Tumors V.1.1. Secondary endpoints included PFS by investigator assessment; objective response rate (ORR), disease control rate, duration of response, and time to response, all by BICR and investigator assessments; overall survival; and safety. Preplanned exploratory biomarker analyses were also performed. RESULTS: From February 2018 through April 2019, 310 patients were enrolled, of which 195 patients were randomized to nivolumab plus SOC (n=127) or SOC (n=68). At 21.5-month minimum follow-up, PFS with nivolumab plus SOC versus SOC did not meet the prespecified threshold for statistical significance; median PFS by BICR was 11.9 months in both arms (HR, 0.81 (95% CI, 0.53 to 1.23); p=0.30). Higher PFS rates after 12 months (18 months: 28% vs 9%), higher ORR (60% vs 46%), and durable responses (median 12.9 vs 9.3 months) were observed with nivolumab plus SOC versus SOC. Grade 3-4 treatment-related adverse events were reported in 75% versus 48% of patients; no new safety signals were identified. CONCLUSIONS: The CheckMate 9X8 trial investigating first-line nivolumab plus SOC versus SOC in patients with mCRC did not meet its primary endpoint of PFS by BICR. Nivolumab plus SOC showed numerically higher PFS rates after 12 months, a higher response rate, and more durable responses compared with SOC alone, with acceptable safety. Further investigation to identify subgroups of patients with mCRC that may benefit from nivolumab plus SOC versus SOC in the first-line setting is warranted. TRIAL REGISTRATION NUMBER: NCT03414983.

A plain language summary of the CheckMate 649 study: nivolumab in combination with chemotherapy compared to chemotherapy alone for untreated advanced or metastatic cancer of the stomach or esophagus.

WHAT IS THIS SUMMARY ABOUT?: This is a summary of the 1-year results of a clinical research study known as CheckMate 649 published in The Lancet in June 2021. The 2-year results on the participants' health and overall quality of life from the same study are in a second publication in Nature in March 2022. Until recently, chemotherapy was the only first treatment option for people with advanced or metastatic gastroesophageal adenocarcinoma who had not been treated before. Patients receiving chemotherapy lived on average for less than 1 year. Nivolumab is an immunotherapy that works by activating a person's immune system to fight back against cancer cells. The goal of CheckMate 649 was to find out if the combination of nivolumab and chemotherapy would help patients with advanced or metastatic gastroesophageal adenocarcinoma live longer and without their cancer getting worse. WHAT WERE THE RESULTS?: Results from the final analysis are reported here. Of 1581 people who took part in the study, 789 received nivolumab and chemotherapy and 792 received chemotherapy. Researchers found that, on average, participants who received nivolumab and chemotherapy lived longer overall than those who received chemotherapy alone. The length of time participants lived without their cancer getting worse was also longer on average with nivolumab and chemotherapy than chemotherapy treatment alone. However, more participants in the nivolumab and chemotherapy group had side effects than those in the chemotherapy group. The three most common side effects in both types of treatment were nausea (urge to vomit), diarrhea and peripheral neuropathy. Participants who received nivolumab and chemotherapy had a lower risk of their cancer symptoms worsening and reported that they were 'less bothered' from side effects of treatment than those receiving chemotherapy alone. WHAT DO THE RESULTS MEAN?: The nivolumab and chemotherapy combination is considered a new standard treatment option and is approved in several countries as a treatment for adults who have not been treated before for their advanced or metastatic gastroesophageal cancer based on results from CheckMate 649. Clinical Trial Registration: NCT02872116 (ClinicalTrials.gov).

First-line nivolumab plus chemotherapy versus chemotherapy alone for advanced gastric, gastro-oesophageal junction, and oesophageal adenocarcinoma (CheckMate 649): a randomised, open-label, phase 3 trial.

BACKGROUND: First-line chemotherapy for advanced or metastatic human epidermal growth factor receptor 2 (HER2)-negative gastric or gastro-oesophageal junction adenocarcinoma has a median overall survival (OS) of less than 1 year. We aimed to evaluate first-line programmed cell death (PD)-1 inhibitor-based therapies in gastric, gastro-oesophageal junction, and oesophageal adenocarcinoma. We report the first results for nivolumab plus chemotherapy versus chemotherapy alone. METHODS: In this multicentre, randomised, open-label, phase 3 trial (CheckMate 649), we enrolled adults (≥18 years) with previously untreated, unresectable, non-HER2-positive gastric, gastro-oesophageal junction, or oesophageal adenocarcinoma, regardless of PD-ligand 1 (PD-L1) expression from 175 hospitals and cancer centres in 29 countries. Patients were randomly assigned (1:1:1 while all three groups were open) via interactive web response technology (block sizes of six) to nivolumab (360 mg every 3 weeks or 240 mg every 2 weeks) plus chemotherapy (capecitabine and oxaliplatin every 3 weeks or leucovorin, fluorouracil, and oxaliplatin every 2 weeks), nivolumab plus ipilimumab, or chemotherapy alone. Primary endpoints for nivolumab plus chemotherapy versus chemotherapy alone were OS or progression-free survival (PFS) by blinded independent central review, in patients whose tumours had a PD-L1 combined positive score (CPS) of five or more. Safety was assessed in all patients who received at least one dose of the assigned treatment. This study is registered with ClinicalTrials.gov, NCT02872116. FINDINGS: From March 27, 2017, to April 24, 2019, of 2687 patients assessed for eligibility, we concurrently randomly assigned 1581 patients to treatment (nivolumab plus chemotherapy [n=789, 50%] or chemotherapy alone [n=792, 50%]). The median follow-up for OS was 13·1 months (IQR 6·7-19·1) for nivolumab plus chemotherapy and 11·1 months (5·8-16·1) for chemotherapy alone. Nivolumab plus chemotherapy resulted in significant improvements in OS (hazard ratio [HR] 0·71 [98·4% CI 0·59-0·86]; p<0·0001) and PFS (HR 0·68 [98 % CI 0·56-0·81]; p<0·0001) versus chemotherapy alone in patients with a PD-L1 CPS of five or more (minimum follow-up 12·1 months). Additional results showed significant improvement in OS, along with PFS benefit, in patients with a PD-L1 CPS of one or more and all randomly assigned patients. Among all treated patients, 462 (59%) of 782 patients in the nivolumab plus chemotherapy group and 341 (44%) of 767 patients in the chemotherapy alone group had grade 3-4 treatment-related adverse events. The most common any-grade treatment-related adverse events (≥25%) were nausea, diarrhoea, and peripheral neuropathy across both groups. 16 (2%) deaths in the nivolumab plus chemotherapy group and four (1%) deaths in the chemotherapy alone group were considered to be treatment-related. No new safety signals were identified. INTERPRETATION: Nivolumab is the first PD-1 inhibitor to show superior OS, along with PFS benefit and an acceptable safety profile, in combination with chemotherapy versus chemotherapy alone in previously untreated patients with advanced gastric, gastro-oesophageal junction, or oesophageal adenocarcinoma. Nivolumab plus chemotherapy represents a new standard first-line treatment for these patients. FUNDING: Bristol Myers Squibb, in collaboration with Ono Pharmaceutical.

Genomic correlates of response to immune checkpoint therapies in clear cell renal cell carcinoma.

Immune checkpoint inhibitors targeting the programmed cell death 1 receptor (PD-1) improve survival in a subset of patients with clear cell renal cell carcinoma (ccRCC). To identify genomic alterations in ccRCC that correlate with response to anti-PD-1 monotherapy, we performed whole-exome sequencing of metastatic ccRCC from 35 patients. We found that clinical benefit was associated with loss-of-function mutations in the PBRM1 gene (P = 0.012), which encodes a subunit of the PBAF switch-sucrose nonfermentable (SWI/SNF) chromatin remodeling complex. We confirmed this finding in an independent validation cohort of 63 ccRCC patients treated with PD-1 or PD-L1 (PD-1 ligand) blockade therapy alone or in combination with anti-CTLA-4 (cytotoxic T lymphocyte-associated protein 4) therapies (P = 0.0071). Gene-expression analysis of PBAF-deficient ccRCC cell lines and PBRM1-deficient tumors revealed altered transcriptional output in JAK-STAT (Janus kinase-signal transducers and activators of transcription), hypoxia, and immune signaling pathways. PBRM1 loss in ccRCC may alter global tumor-cell expression profiles to influence responsiveness to immune checkpoint therapy.

Maternal and zygotic Zfp57 modulate NOTCH signaling in cardiac development.

Zfp57 is a maternal-zygotic effect gene that maintains genomic imprinting. Here we report that Zfp57 mutants exhibited a variety of cardiac defects including atrial septal defect (ASD), ventricular septal defect (VSD), thin myocardium, and reduced trabeculation. Zfp57 maternal-zygotic mutant embryos displayed more severe phenotypes with higher penetrance than the zygotic ones. Cardiac progenitor cells exhibited proliferation and differentiation defects in Zfp57 mutants. ZFP57 is a master regulator of genomic imprinting, so the DNA methylation imprint was lost in embryonic heart without ZFP57. Interestingly, the presence of imprinted DLK1, a target of ZFP57, correlated with NOTCH1 activation in cardiac cells. These results suggest that ZFP57 may modulate NOTCH signaling during cardiac development. Indeed, loss of ZFP57 caused loss of NOTCH1 activation in embryonic heart with more severe loss observed in the maternal-zygotic mutant. Maternal and zygotic functions of Zfp57 appear to play redundant roles in NOTCH1 activation and cardiomyocyte differentiation. This serves as an example of a maternal effect that can influence mammalian organ development. It also links genomic imprinting to NOTCH signaling and particular developmental functions.

Hematopoietic stem cells lacking Ott1 display aspects associated with aging and are unable to maintain quiescence during proliferative stress.

Aging degrades hematopoietic stem cell (HSC) functions, including stress response; however, the involved molecular pathways are incompletely defined. Murine BM conditionally deleted for One-Twenty-Two-1 (Ott1), is able to maintain lifelong hematopoiesis and has preserved numbers of long-term HSCs, yet cannot repopulate nor sustain itself after transplantation against a competitor even when Ott1 is excised after engraftment. We show, specifically under replicative stress, that Ott1-deleted HSCs have a significant reduction of the G(0) cell-cycle fraction associated with self-renewal and undergo early failure. Therefore, Ott1 is required to preserve HSC quiescence during stress but not steady-state hematopoiesis. Reduced tolerance of replicative stress, increased myeloid potential, and greater absolute numbers are mutual characteristics of both Ott1-deleted and aged HSCs, and comparison of their gene expression profiles reveals a shared signature. Ott1-deleted HSCs share multiple aging-associated physiologic changes, including increases in NF-κB activation and DNA damage. Loss of Ott1 causes increased reactive oxygen species; however, antioxidant treatment does not rescue the competitive defect, indicating the existence of additional essential Ott1-dependent HSC pathways. In conclusion, our data establish a requirement for Ott1 in stress hematopoiesis and suggest that Ott1-dependent processes may converge with those affected by aging.

Zinc finger protein ZFP57 requires its co-factor to recruit DNA methyltransferases and maintains DNA methylation imprint in embryonic stem cells via its transcriptional repression domain.

Previously, we discovered that ZFP57 is a maternal-zygotic effect gene, and it maintains DNA methylation genomic imprint at multiple imprinted regions in mouse embryos. Despite these findings, it remains elusive how DNA methyltransferases are targeted to the imprinting control regions to initiate and maintain DNA methylation imprint. To gain insights into these essential processes in genomic imprinting, we examined how ZFP57 maintains genomic DNA methylation imprint in mouse embryonic stem (ES) cells. Here we demonstrate that the loss of ZFP57 in mouse ES cells led to a complete loss of genomic DNA methylation imprint at multiple imprinted regions, similar to its role in mouse embryos. However, reintroduction of ZFP57 into Zfp57-null ES cells did not result in reacquisition of DNA methylation imprint, suggesting that the memory for genomic imprinting had been lost or altered in Zfp57-null ES cells in culture. Interestingly, ZFP57 and DNA methyltransferases could form complexes in the presence of KAP1/TRIM28/TIF1ß when co-expressed in COS cells. We also found that the wild-type exogenous ZFP57 but not the mutant ZFP57 lacking the KRAB box that interacts with its co-factor KAP1/TRIM28/TIF1ß could substitute for the endogenous ZFP57 in maintaining the DNA methylation imprint in ES cells. These results suggest that ZFP57 may recruit DNA methyltransferases to its target regions to maintain DNA methylation imprint, and this interaction is likely facilitated by KAP1/TRIM28/TIF1ß.

Hedgehog signaling is dispensable for adult murine hematopoietic stem cell function and hematopoiesis.

We report the unexpected finding that loss of Hh signaling through conditional deletion of Smoothened (Smo) in the adult hematopoietic compartment has no apparent effect on adult hematopoiesis, including peripheral blood count, number or cell-cycle status of stem or progenitor cells, hematopoietic colony-forming potential, long-term repopulating activity in competitive repopulation assays, or stress response to serial 5-fluorouracil treatment. Furthermore, pharmacologic inhibition of Hh signaling with a potent and selective small molecule antagonist has no substantive effect on hematopoiesis in the mouse. In addition, Hh signaling is not required for the development of MLL-AF9-mediated acute myeloid leukemia (AML). Taken together, these data demonstrate that Hh signaling is dispensable for normal hematopoietic development and hematopoietic stem cell function, indicating that targeting of Hh signaling in solid tumors is not likely to result in hematopoietic toxicity. Furthermore, the Hh pathway may not be a compelling target in certain hematopoietic malignancies.

The OTT-MAL fusion oncogene activates RBPJ-mediated transcription and induces acute megakaryoblastic leukemia in a knockin mouse model.

Acute megakaryoblastic leukemia (AMKL) is a form of acute myeloid leukemia (AML) associated with a poor prognosis. The genetics and pathophysiology of AMKL are not well understood. We generated a knockin mouse model of the one twenty-two-megakaryocytic acute leukemia (OTT-MAL) fusion oncogene that results from the t(1;22)(p13;q13) translocation specifically associated with a subtype of pediatric AMKL. We report here that OTT-MAL expression deregulated transcriptional activity of the canonical Notch signaling pathway transcription factor recombination signal binding protein for immunoglobulin kappa J region (RBPJ) and caused abnormal fetal megakaryopoiesis. Furthermore, cooperation between OTT-MAL and an activating mutation of the thrombopoietin receptor myeloproliferative leukemia virus oncogene (MPL) efficiently induced a short-latency AMKL that recapitulated all the features of human AMKL, including megakaryoblast hyperproliferation and maturation block, thrombocytopenia, organomegaly, and extensive fibrosis. Our results establish that concomitant activation of RBPJ (Notch signaling) and MPL (cytokine signaling) transforms cells of the megakaryocytic lineage and suggest that specific targeting of these pathways could be of therapeutic value for human AMKL.

Ott1 (Rbm15) is essential for placental vascular branching morphogenesis and embryonic development of the heart and spleen.

The infant leukemia-associated gene Ott1 (Rbm15) has broad regulatory effects within murine hematopoiesis. However, germ line Ott1 deletion results in fetal demise prior to embryonic day 10.5, indicating additional developmental requirements for Ott1. The spen gene family, to which Ott1 belongs, has a transcriptional activation/repression domain and RNA recognition motifs and has a significant role in the development of the head and thorax in Drosophila melanogaster. Early Ott1-deficient embryos show growth retardation and incomplete closure of the notochord. Further analysis demonstrated placental defects in the spongiotrophoblast and syncytiotrophoblast layers, resulting in an arrest of vascular branching morphogenesis. The rescue of the placental defect using a conditional allele with a trophoblast-sparing cre transgene allowed embryos to form a normal placenta and survive gestation. This outcome showed that the process of vascular branching morphogenesis in Ott1-deficient animals was regulated by the trophoblast compartment rather than the fetal vasculature. Mice surviving to term manifested hyposplenia and abnormal cardiac development. Analysis of global gene expression of Ott1-deficient embryonic hearts showed an enrichment of hypoxia-related genes and a significant alteration of several candidate genes critical for cardiac development. Thus, Ott1-dependent pathways, in addition to being implicated in leukemogenesis, may also be important for the pathogenesis of placental insufficiency and cardiac malformations.

Efficacy of TG101348, a selective JAK2 inhibitor, in treatment of a murine model of JAK2V617F-induced polycythemia vera.

We report that TG101348, a selective small-molecule inhibitor of JAK2 with an in vitro IC50 of approximately 3 nM, shows therapeutic efficacy in a murine model of myeloproliferative disease induced by the JAK2V617F mutation. In treated animals, there was a statistically significant reduction in hematocrit and leukocyte count, a dose-dependent reduction/elimination of extramedullary hematopoiesis, and, at least in some instances, evidence for attenuation of myelofibrosis. There were no apparent toxicities and no effect on T cell number. In vivo responses were correlated with surrogate endpoints, including reduction/elimination of JAK2V617F disease burden assessed by quantitative genomic PCR, suppression of endogenous erythroid colony formation, and in vivo inhibition of JAK-STAT signal transduction as assessed by flow cytometric measurement of phosphorylated Stat5.

FLT3 mutations confer enhanced proliferation and survival properties to multipotent progenitors in a murine model of chronic myelomonocytic leukemia.

Despite their known transforming properties, the effects of leukemogenic FLT3-ITD mutations on hematopoietic stem and multipotent progenitor cells and on hematopoietic differentiation are not well understood. We report a mouse model harboring an ITD in the murine Flt3 locus that develops myeloproliferative disease resembling CMML and further identified FLT3-ITD mutations in a subset of human CMML. These findings correlated with an increase in number, cell cycling, and survival of multipotent stem and progenitor cells in an ITD dose-dependent manner in animals that exhibited alterations within their myeloid progenitor compartments and a block in normal B cell development. This model provides insights into the consequences of constitutive signaling by an oncogenic tyrosine kinase on hematopoietic progenitor quiescence, function, and cell fate.

Ott1(Rbm15) has pleiotropic roles in hematopoietic development.

OTT1(RBM15) was originally described as a 5' translocation partner of the MAL(MKL1) gene in t(1,22)(p13;q13) infant acute mega karyocytic leukemia. OTT1 has no established physiological function, but it shares homology with the spen/Mint/SHARP family of proteins defined by three amino-terminal RNA recognition motifs and a carboxyl-terminal SPOC (Spen paralog and ortholog carboxyl-terminal) domain believed to act as a transcriptional repressor. To define the role of OTT1 in hematopoiesis and help elucidate the mechanism of t(1,22) acute megakaryocytic leukemia pathogenesis, a conditional allele of Ott1 was generated in mice. Deletion of Ott1 in adult mice caused a loss of peripheral B cells due to a block in pro/pre-B differentiation. There is myeloid and megakaryocytic expansion in spleen and bone marrow, an increase in the Lin(-)Sca-1(+)c-Kit(+) compartment that includes hematopoietic stem cells, and a shift in progenitor fate toward granulocyte differentiation. These data show a requirement for Ott1 in B lymphopoiesis, and inhibitory roles in the myeloid, megakaryocytic, and progenitor compartments. The ability of Ott1 to affect hematopoietic cell fate and expansion in multiple lineages is a novel attribute for a spen family member and delineates Ott1 from other known effectors of hematopoietic development. It is plausible that dysregulation of Ott1-dependent hematopoietic developmental pathways, in particular those affecting the megakaryocyte lineage, may contribute to OTT1-MAL-mediated leukemogenesis.

FoxOs are critical mediators of hematopoietic stem cell resistance to physiologic oxidative stress.

To understand the role of FoxO family members in hematopoiesis, we conditionally deleted FoxO1, FoxO3, and FoxO4 in the adult hematopoietic system. FoxO-deficient mice exhibited myeloid lineage expansion, lymphoid developmental abnormalities, and a marked decrease of the lineage-negative Sca-1+, c-Kit+ (LSK) compartment that contains the short- and long-term hematopoietic stem cell (HSC) populations. FoxO-deficient bone marrow had defective long-term repopulating activity that correlated with increased cell cycling and apoptosis of HSC. Notably, there was a marked context-dependent increase in reactive oxygen species (ROS) in FoxO-deficient HSC compared with wild-type HSC that correlated with changes in expression of genes that regulate ROS. Furthermore, in vivo treatment with the antioxidative agent N-acetyl-L-cysteine resulted in reversion of the FoxO-deficient HSC phenotype. Thus, FoxO proteins play essential roles in the response to physiologic oxidative stress and thereby mediate quiescence and enhanced survival in the HSC compartment, a function that is required for its long-term regenerative potential.

JAK2T875N is a novel activating mutation that results in myeloproliferative disease with features of megakaryoblastic leukemia in a murine bone marrow transplantation model.

Acute megakaryoblastic leukemia (AMKL) is a subtype of acute myeloid leukemia associated with a poor prognosis. However, there are relatively few insights into the genetic etiology of AMKL. We developed a screening assay for mutations that cause AMKL, based on the hypothesis that constitutive activation of STAT5 would be a biochemical indicator of mutation in an upstream effector tyrosine kinase. We screened human AMKL cell lines for constitutive STAT5 activation, and then used an approach combining mass spectrometry identification of tyrosine phosphorylated proteins and growth inhibition in the presence of selective small molecule tyrosine kinase inhibitors that would inform DNA sequence analysis of candidate tyrosine kinases. Using this strategy, we identified a new JAK2T875N mutation in the AMKL cell line CHRF-288-11. JAK2T875N is a constitutively activated tyrosine kinase that activates downstream effectors including STAT5 in hematopoietic cells in vitro. In a murine transplant model, JAK2T875N induced a myeloproliferative disease characterized by features of AMKL, including megakaryocytic hyperplasia in the spleen; impaired megakaryocyte polyploidization; and increased reticulin fibrosis of the bone marrow and spleen. These findings provide new insights into pathways and therapeutic targets that contribute to the pathogenesis of AMKL.

The small molecule tyrosine kinase inhibitor AMN107 inhibits TEL-PDGFRbeta and FIP1L1-PDGFRalpha in vitro and in vivo.

AMN107 is a small molecule tyrosine kinase inhibitor developed, in the first instance, as a potent inhibitor of breakpoint cluster region-abelson (BCR-ABL). We tested its effectiveness against fusion tyrosine kinases TEL-platelet-derived growth factor receptorbeta (TEL-PDGFRbeta) and FIP1-like-1 (FIP1L1)-PDGFRalpha, which cause chronic myelomonocytic leukemia and hypereosinophilic syndrome, respectively. In vitro, AMN107 inhibited proliferation of Ba/F3 cells transformed by both TEL-PDGFRbeta and FIP1L1-PDGFRalpha with IC50 (inhibitory concentration 50%) values less than 25 nM and inhibited phosphorylation of the fusion kinases and their downstream signaling targets. The imatinib mesylate-resistant mutant TEL-PDGFRbeta T681I was sensitive to AMN107, whereas the analogous mutation in FIP1L1-PDGFRalpha, T674I, was resistant. In an in vivo bone marrow transplantation assay, AMN107 effectively treated myeloproliferative disease induced by TEL-PDGFRbeta and FIP1L1-PDGFRalpha, significantly increasing survival and disease latency and reducing disease severity as assessed by histopathology and flow cytometry. In summary, AMN107 can inhibit myeloid proliferation driven by TEL-PDGFRbeta and FIP1L1-PDGFRalpha and may be a useful drug for treatment of patients with myeloproliferative disease who harbor these kinase fusions.