Mavorixafor, an Orally Bioavailable CXCR4 Antagonist, Increases Immune Cell Infiltration and Inflammatory Status of Tumor Microenvironment in Patients with Melanoma.

Purpose: Mavorixafor is an oral, selective inhibitor of the CXCR4 chemokine receptor that modulates immune cell trafficking. A biomarker-driven phase Ib study (NCT02823405) was conducted in 16 patients with melanoma to investigate the hypothesis that mavorixafor favorably modulates immune cell profiles in the tumor microenvironment (TME) and to evaluate the safety of mavorixafor alone and in combination with pembrolizumab. Experimental Design: Serial biopsies of melanoma lesions were assessed after 3 weeks of mavorixafor monotherapy and after 6 weeks of combination treatment for immune cell markers by NanoString analysis for gene expression and by multiplexed immunofluorescent staining for in situ protein expression. Serum samples taken at biopsy timepoints were evaluated for key chemokine and cytokine alterations using the Myriad Rules Based Medicine multiplex immunoassays. Results: Within the TME, mavorixafor alone increased CD8+ T-cell infiltration, granzyme B signal, antigen presentation machinery, and both tumor inflammatory signature (TIS) and IFNγ gene expression signature scores. Increases in the key serum cytokines CXCL9 and CXCL10 were further enhanced when mavorixafor was combined with pembrolizumab. Adverse events (AE), as assessed by the investigator according to NCI Common Terminology Criteria for Adverse Events (v4.03), related to either mavorixafor or pembrolizumab (≥15%) were diarrhea, fatigue, maculopapular rash, and dry eye. Reported AEs were all ≤ grade 3. Conclusion/Discussion: Treatment with single-agent mavorixafor resulted in enhanced immune cell infiltration and activation in the TME, leading to increases in TIS and IFNγ gene signatures. Mavorixafor as a single agent, and in combination with pembrolizumab, has an acceptable safety profile. These data support further investigation of the use of mavorixafor for patients unresponsive to checkpoint inhibitors. Significance: Despite survival improvements in patients with melanoma treated with checkpoint inhibitor therapy, a significant unmet medical need exists for therapies that enhance effectiveness. We propose that mavorixafor sensitizes the melanoma tumor microenvironment and enhances the activity of checkpoint inhibitors, and thereby may translate to a promising treatment for broader patient populations.

A phase 1b trial of the CXCR4 inhibitor mavorixafor and nivolumab in advanced renal cell carcinoma patients with no prior response to nivolumab monotherapy.

Background The CXCR4 chemokine receptor promotes tumor survival through mechanisms that include suppressing antitumor immune responses. Mavorixafor (X4P-001) is an oral, selective, allosteric CXCR4 inhibitor that decreases the recruitment of immunosuppressive cells into the tumor microenvironment and increases activated cytotoxic Tcell infiltration. Methods Patients with metastatic clear cell renal cell carcinoma (ccRCC) unresponsive to nivolumab monotherapy received oral mavorixafor 400 mg daily plus 240 mg intravenous nivolumab every 2 weeks. Results Nine patients were enrolled, median age 65 years. At baseline 4 had progressive disease (PD) and 5 had stable disease (SD). One of 5 patients with SD at study entry on prior nivolumab monotherapy had a partial response (PR) on combination treatment; all 4 patients with PD at study entry had a best response of SD with the combination treatment (median duration: 6.7 months; range: 3.7-14.7). Four patients discontinued therapy due to treatment-related adverse events (AEs). Grade ≥ 3 drug-related AEs were elevated alanine and aspartate aminotransferase (2 patients each); and autoimmune hepatitis, chronic kidney disease, increased lipase, maculopapular rash, and mucosal inflammation (1 patient each). A robust increase in levels of chemokine (C-X-C motif) ligand 9 CXCL9 on mavorixafor appeared to correlate with clinical benefit. Conclusions The CXCR4 inhibition mediated by mavorixafor, in combination with PD-1 blockade to enhance antitumor immune responses in patients unresponsive to checkpoint inhibitor monotherapy, is worthy of further study. Mavorixafor and nivolumab combination therapy in patients with advanced ccRCC demonstrated potential antitumor activity and a manageable safety profile.Trial registration: ClinicalTrials.gov identifier: NCT02923531. Date of registration: October 04, 2016.

A Phase I Study of the CDK4/6 Inhibitor Ribociclib (LEE011) in Pediatric Patients with Malignant Rhabdoid Tumors, Neuroblastoma, and Other Solid Tumors.

Purpose: The cyclin-dependent kinase (CDK) 4/6 inhibitor, ribociclib (LEE011), displayed preclinical activity in neuroblastoma and malignant rhabdoid tumor (MRT) models. In this phase I study, the maximum tolerated dose (MTD) and recommended phase II dose (RP2D), safety, pharmacokinetics (PK), and preliminary activity of single-agent ribociclib were investigated in pediatric patients with neuroblastoma, MRT, or other cyclin D-CDK4/6-INK4-retinoblastoma pathway-altered tumors.Experimental Design: Patients (aged 1-21 years) received escalating once-daily oral doses of ribociclib (3-weeks-on/1-week-off). Dose escalation was guided by a Bayesian logistic regression model with overdose control and real-time PK.Results: Thirty-two patients (median age, 5.5 years) received ribociclib 280, 350, or 470 mg/m2 Three patients had dose-limiting toxicities of grade 3 fatigue (280 mg/m2; n = 1) or grade 4 thrombocytopenia (470 mg/m2; n = 2). Most common treatment-related adverse events (AE) were hematologic: neutropenia (72% all-grade/63% grade 3/4), leukopenia (63%/38%), anemia (44%/3%), thrombocytopenia (44%/28%), and lymphopenia (38%/19%), followed by vomiting (38%/0%), fatigue (25%/3%), nausea (25%/0%), and QTc prolongation (22%/0%). Ribociclib exposure was dose-dependent at 350 and 470 mg/m2 [equivalent to 600 (RP2D)-900 mg in adults], with high interpatient variability. Best overall response was stable disease (SD) in nine patients (seven with neuroblastoma, two with primary CNS MRT); five patients achieved SD for more than 6, 6, 8, 12, and 13 cycles, respectively.Conclusions: Ribociclib demonstrated acceptable safety and PK in pediatric patients. MTD (470 mg/m2) and RP2D (350 mg/m2) were equivalent to those in adults. Observations of prolonged SD support further investigation of ribociclib combined with other agents in neuroblastoma and MRT. Clin Cancer Res; 23(10); 2433-41. ©2017 AACR.

Preclinical Therapeutic Synergy of MEK1/2 and CDK4/6 Inhibition in Neuroblastoma.

Purpose: Neuroblastoma is treated with aggressive multimodal therapy, yet more than 50% of patients experience relapse. We recently showed that relapsed neuroblastomas frequently harbor mutations leading to hyperactivated ERK signaling and sensitivity to MEK inhibition therapy. Here we sought to define a synergistic therapeutic partner to potentiate MEK inhibition.Experimental Design: We first surveyed 22 genetically annotated human neuroblastoma-derived cell lines (from 20 unique patients) for sensitivity to the MEK inhibitor binimetinib. After noting an inverse correlation with sensitivity to ribociclib (CDK4/6 inhibitor), we studied the combinatorial effect of these two agents using proliferation assays, cell-cycle analysis, Ki67 immunostaining, time-lapse microscopy, and xenograft studies.Results: Sensitivity to binimetinib and ribociclib was inversely related (r = -0.58, P = 0.009). MYCN amplification status and expression were associated with ribociclib sensitivity and binimetinib resistance, whereas increased MAPK signaling was the main determinant of binimetinib sensitivity and ribociclib resistance. Treatment with both compounds resulted in synergistic or additive cellular growth inhibition in all lines tested and significant inhibition of tumor growth in three of four xenograft models of neuroblastoma. The augmented growth inhibition was attributed to diminished cell-cycle progression that was reversible upon removal of drugs.Conclusions: Here we demonstrate that combined binimetinib and ribociclib treatment shows therapeutic synergy across a broad panel of high-risk neuroblastoma preclinical models. These data support testing this combination therapy in relapsed high-risk neuroblastoma patients, with focus on cases with hyperactivated RAS-MAPK signaling. Clin Cancer Res; 23(7); 1785-96. ©2016 AACR.

A Phase I Study of the Cyclin-Dependent Kinase 4/6 Inhibitor Ribociclib (LEE011) in Patients with Advanced Solid Tumors and Lymphomas.

PURPOSE: Ribociclib (an oral, highly specific cyclin-dependent kinase 4/6 inhibitor) inhibits tumor growth in preclinical models with intact retinoblastoma protein (Rb+). This first-in-human study investigated the MTD, recommended dose for expansion (RDE), safety, preliminary activity, pharmacokinetics, and pharmacodynamics of ribociclib in patients with Rb+ advanced solid tumors or lymphomas. EXPERIMENTAL DESIGN: Patients received escalating doses of ribociclib (3-weeks-on/1-week-off or continuous). Dose escalation was guided by a Bayesian Logistic Regression Model with overdose control principle. RESULTS: Among 132 patients, 125 received ribociclib 3-weeks-on/1-week-off and 7 were dosed continuously. Nine dose-limiting toxicities were observed among 70 MTD/RDE evaluable patients during cycle 1, most commonly neutropenia (n = 3) and thrombocytopenia (n = 2). The MTD and RDE were established as 900 and 600 mg/day 3-weeks-on/1-week-off, respectively. Common treatment-related adverse events were (all-grade; grade 3/4) neutropenia (46%; 27%), leukopenia (43%; 17%), fatigue (45%; 2%), and nausea (42%; 2%). Asymptomatic Fridericia's corrected QT prolongation was specific to doses ≥600 mg/day (9% of patients at 600 mg/day; 33% at doses >600 mg/day). Plasma exposure increases were slightly higher than dose proportional; mean half-life at the RDE was 32.6 hours. Reduced Ki67 was observed in paired skin and tumor biopsies, consistent with ribociclib-mediated antiproliferative activity. There were 3 partial responses and 43 patients achieved a best response of stable disease; 8 patients were progression-free for >6 months. CONCLUSIONS: Ribociclib demonstrated an acceptable safety profile, dose-dependent plasma exposure, and preliminary signs of clinical activity. Phase I-III studies of ribociclib are under way in various indications. Clin Cancer Res; 22(23); 5696-705. ©2016 AACR.

Functional, chemical genomic, and super-enhancer screening identify sensitivity to cyclin D1/CDK4 pathway inhibition in Ewing sarcoma.

Ewing sarcoma is an aggressive bone and soft tissue tumor in children and adolescents, with treatment remaining a clinical challenge. This disease is mediated by somatic chromosomal translocations of the EWS gene and a gene encoding an ETS transcription factor, most commonly, FLI1. While direct targeting of aberrant transcription factors remains a pharmacological challenge, identification of dependencies incurred by EWS/FLI1 expression would offer a new therapeutic avenue. We used a combination of super-enhancer profiling, near-whole genome shRNA-based and small-molecule screening to identify cyclin D1 and CDK4 as Ewing sarcoma-selective dependencies. We revealed that super-enhancers mark Ewing sarcoma specific expression signatures and EWS/FLI1 target genes in human Ewing sarcoma cell lines. Particularly, a super-enhancer regulates cyclin D1 and promotes its expression in Ewing sarcoma. We demonstrated that Ewing sarcoma cells require CDK4 and cyclin D1 for survival and anchorage-independent growth. Additionally, pharmacologic inhibition of CDK4 with selective CDK4/6 inhibitors led to cytostasis and cell death of Ewing sarcoma cell lines in vitro and growth delay in an in vivo Ewing sarcoma xenograft model. These results demonstrated a dependency in Ewing sarcoma on CDK4 and cyclin D1 and support exploration of CDK4/6 inhibitors as a therapeutic approach for patients with this disease.

Dual CDK4/CDK6 inhibition induces cell-cycle arrest and senescence in neuroblastoma.

PURPOSE: Neuroblastoma is a pediatric cancer that continues to exact significant morbidity and mortality. Recently, a number of cell-cycle proteins, particularly those within the Cyclin D/CDK4/CDK6/RB network, have been shown to exert oncogenic roles in neuroblastoma, suggesting that their therapeutic exploitation might improve patient outcomes. EXPERIMENTAL PROCEDURES: We evaluated the effect of dual CDK4/CDK6 inhibition on neuroblastoma viability using LEE011 (Novartis Oncology), a highly specific CDK4/6 inhibitor. RESULTS: Treatment with LEE011 significantly reduced proliferation in 12 of 17 human neuroblastoma-derived cell lines by inducing cytostasis at nanomolar concentrations (mean IC50 = 307 ± 68 nmol/L in sensitive lines). LEE011 caused cell-cycle arrest and cellular senescence that was attributed to dose-dependent decreases in phosphorylated RB and FOXM1, respectively. In addition, responsiveness of neuroblastoma xenografts to LEE011 translated to the in vivo setting in that there was a direct correlation of in vitro IC50 values with degree of subcutaneous xenograft growth delay. Although our data indicate that neuroblastomas sensitive to LEE011 were more likely to contain genomic amplification of MYCN (P = 0.01), the identification of additional clinically accessible biomarkers is of high importance. CONCLUSIONS: Taken together, our data show that LEE011 is active in a large subset of neuroblastoma cell line and xenograft models, and supports the clinical development of this CDK4/6 inhibitor as a therapy for patients with this disease. Clin Cancer Res; 19(22); 6173-82. ©2013 AACR.

Bortezomib, bendamustine, and rituximab in patients with relapsed or refractory follicular lymphoma: the phase II VERTICAL study.

PURPOSE: The aims of this multicenter study were to evaluate the response rate, progression-free survival, and toxicity of the combination of bortezomib, bendamustine, and rituximab in patients with follicular lymphoma whose disease was relapsed or refractory to prior treatment. PATIENTS AND METHODS: Patients received five 35-day cycles of bortezomib, bendamustine, and rituximab: bortezomib administered intravenously (IV) at a dose of 1.6 mg/m(2) on days 1, 8, 15, and 22, cycles one to five; bendamustine 50, 70, or 90 mg/m(2) IV over a 60-minute infusion on days 1 and 2, cycles one to five; and rituximab 375 mg/m(2) on days 1, 8, 15, and 22 of cycle one and day 1 of subsequent cycles. Patients were assessed using the International Workshop Response Criteria, with the primary end point of 60% complete response rate. RESULTS: Seventy-three patients were enrolled. During the dose-escalation phase, the maximum-tolerated dose for bendamustine was not reached; the 90 mg/m(2) dose level was expanded for the efficacy assessment, and a total of 63 patients received bendamustine 90 mg/m(2). In these 63 patients, the overall response rate was 88% (including 53% complete response). Median duration of response was 11.7 months (95% CI, 9.2 to 13.3). Median progression-free survival was 14.9 months (95% CI, 11.1 to 23.7). Toxicities were manageable; myelosuppression was the main toxicity (25% and 14% of patients experienced grade 3 to 4 neutropenia and grade 3 to 4 thrombocytopenia, respectively). Transient grade 3 to 4 neuropathy occurred in 11% of patients. CONCLUSION: The combination of bortezomib, bendamustine, and rituximab is highly active in patients with follicular lymphoma who have received previous treatment.

Once daily enoxaparin for outpatient treatment of acute venous thromboembolism: a case-control study.

We studied the efficacy and safety of an investigational enoxaparin regimen, 1.5 mg/kg once daily, as a bridge to warfarin for the outpatient treatment of acute venous thromboembolism. We undertook a case-control design. We enrolled 40 acute venous thromboembolism cases prospectively and matched them by age, gender, and location of venous thromboembolism to 80 previously treated controls. All controls had received enoxaparin 1 mg/kg twice daily. The primary end point was recurrent venous thromboembolism. We followed the cases for 30 days. We discontinued enoxaparin after we achieved the target international normalized ratio between 2.0 and 3.0. One case (2.9%) and three controls (3.8%) had recurrent venous thromboembolic events (P = 1.00). There were no major bleeding complications in the case group, compared to 3 (3.8%) in the control group (P = .55). Once daily enoxaparin, 1.5 mg/kg, as a bridge to warfarin was as effective with a similar safety profile as twice daily enoxaparin, 1mg/kg, for initial treatment of acute venous thromboembolism in the outpatient setting. This case-control study provides the rationale for undertaking a randomized controlled trial comparing enoxaparin 1.5 mg/kg once daily versus enoxaparin 1.0 mg/kg twice daily as a bridge to warfarin in outpatients with acute venous thromboembolism.

Gastrointestinal complications after 3 months of dual antiplatelet therapy for drug-eluting stents as assessed by wireless capsule endoscopy.

Little is known about the frequency of symptomatic and asymptomatic gastrointestinal complications of dual antiplatelet therapy. We recruited 30 patients between 18 and 80 years who were started on aspirin and clopidogrel following percutaneous coronary intervention with drug-eluting stents. We hypothesized that the 3 months of dual antiplatelet therapy would be associated with frequent upper gastrointestinal endoscopic abnormalities. Patients were followed with weekly phone calls to inquire about the new gastrointestinal symptoms and after a minimum of 80 days, their upper gastrointestinal mucosa was visualized with PillCam ESO wireless capsule endoscopy. 18 (90%) of the 20 successful wireless capsule endoscopies revealed at least 1 type of gastrointestinal mucosal lesion. Gastric erosions (n = 14, 70%) were the most common abnormality. We believe this is the first noninvasive endoscopic study of gastrointestinal complications of dual antiplatelet therapy in patients who undergo percutaneous coronary intervention with drug-eluting stents. Future studies should expand on our observations to determine whether prophylaxis with proton pump inhibitors is warranted.