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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.

Antibody panels used for mIF analyses.

Serum cytokine and chemokine changes at the end of the 3-week monotherapy period compared to baseline.

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.

Shared TCR TIL sequences taken from tumor biopsy of patient #5 at various timepoints.

Depiction of T cell clone mobilization from peripheral blood to melanoma site on day 1 and at EOT.

Supplementary Figure 2 - PDF file 55K, Neuroblastoma tissue microarray. A tissue microarray demonstrates expression of RB in neuroblastoma that is higher in high-risk and MYCN amplified samples compared to low-risk or non-amplified samples (p = 0.03)

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Supplementary Figure 5 - PDF file 138K, CDK4/6 inhibition does not induce cytotoxicity in neuroblastoma. (A) Caspase 3/7 activation and (B) PARP cleavage were not observed in cell lines with demonstrated sensitivity to LEE011. SN38, a known cytotoxic agent, was used as a positive control

Supplementary Table 1 - PDF file 78K, Genomic aberrations in the Cyclin D/CDK4/CDK6/RB pathway occur frequently in neuroblastoma cell lines

Supplementary Figure 4 - PDF file 88K, Protein level expression of FOXM1 in neuroblastoma

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.

Supplementary Figure 1 - PDF file 56K, Expression of CDK4, CDK6, CCND1, and RB1 in neuroblastoma patients. Expression analysis of neuroblastoma primary tumors demonstrates that CDK4 expression, and to a lesser extent RB1 expression, is higher in high-risk neuroblastoma patients than in low risk patients

Supplementary Figure S1. Neuroblastoma cell lines are sensitive to binimetinib. Supplementary Figure S2. Gene expression profiling of human neuroblastoma cell lines with regards to relative sensitivity to MEK1/2 and CDK4/6 inhibition Supplementary Figure S3. Combined MEK and CDK4/6 inhibition does not induce significant levels of apoptosis or senescence. Supplementary Figure S4. G1 arrest induced by MEK1/2 and CDK4/6 inhibition is reversible. Supplementary Figure S5. Gene expression profiling of human neuroblastoma cell lines with regards to the synergy observed from combined binimetinib-ribociclib treatment. Figure S6. Neuroblastoma xenografts are sensitive to combined binimetinib-ribociclib treatment.

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.

Supplementary Figure 6 - PDF file 75K, Statistical analysis of in vivo growth suppression. (A) Growth rates of BE2C, 1643, and EBC1 xenografts treated with 200 mg/kg LEE011 or vehicle, as determined by linear mixed effects analysis. (B) Summary table of statistics

Table S1. Specific mutations of genes listed in Table 1. Table S2. Foundation Medicine sequencing calls of cancer-specific gene panel. Table S3. Gene lists corresponding to microarray analysis described in Figures 1A and 1B: (A) binimetinib and (B) ribociclib. Significant genes (in bold type) are defined as having an adjusted p-value of 0.25 or less.

This document contains Supplementary information, including materials and methods as well as Figure Legends for the Supplementary Figures.

Supplementary Table 2 - PDF file 48KB, Copy number variations within the Cyclin D/CDK4/CDK6/RB pathway occur in high-risk neuroblastoma patients

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.

Fig. S1. Waterfall plot of duration of exposure vs. best percentage change from baseline; Figure S2. Duration of exposure in patients with stable disease treated for at least four cycles; Figure S3. Duration of exposure, best percentage change in target lesion, and genetic profile for the 53 patients with available genetic data.

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.

Supplementary Figure 3 - PDF file 127K, MYCN expression is inversely correlated with LEE011 sensitivity. (A) High mRNA expression of MYCN correlates with low LEE011 IC50s (r = -0.55, p = 0.02). This correlation is further strengthened (r = -0.7, p = 0.003) by the removal of two outliers, SKNSH (IC50 = 148 nM) and its subclone, SY5Y (IC50 = 154 nM). (B) Sensitive cell lines also tend to express higher levels of MYCN protein than resistant cell lines

Background: PARP7 is a stress-induced monoART that suppresses the cellular type I interferon (IFN) response following cytosolic nucleic acid sensing. RBN-2397 is a first-in-class PARP7 inhibitor that induces IFN and an adaptive immune response. The tumor-intrinsic immunomodulatory mechanism of RBN-2397 and preliminary antitumor activity in patients (pts) was demonstrated during dose escalation (Falchook, ASCO 2021; Kuplast-Barr, AACR 2022). Methods: Pts with solid tumors were treated with RBN-2397 at the RP2D of 200 mg BID in 3 expansion cohorts: squamous cell carcinoma of the lung (SCCL), head and neck squamous cell carcinoma (HNSCC), and hormone receptor-positive breast cancer (HR+ BC). Objectives of the expansion phase included safety, pharmacokinetics, pharmacodynamics, and antitumor activity. Results: As of 2 July 2022, 31 pts have been treated: SCCL (n=13), HNSCC (n=10), and HR+ BC (n=8). RBN-2397-related AEs (all grades >10%) included dysgeusia (42%, n=13), nausea (26%, n=8), fatigue (23%, n=7), with Grade 3 events of nausea and pleural infection (each n=1) and ALT/AST increase (n=2), and no Grade 4 events. No significant chronic toxicities were observed. The disease control rate in response-evaluable pts was 44% in SCCL (stable disease [SD] in 4/9 pts), 71% in HNSCC (RECIST partial response [PR] for 12+ months in 1/7; SD in 4/7), and 29% in HR+ BC (SD in 2/7). Biomarker analyses confirmed PARP7 mRNA expression in all baseline biopsies, with H-scores higher in tumor cells than in stromal cells (n=26, H-score range 66-256, P Conclusions: RBN-2397 was well tolerated at biologically active drug exposures, with preliminary antitumor activity observed. Paired tumor biopsy translational studies demonstrated the immunomodulatory mechanism of RBN-2397 and support the ongoing trial of RBN-2397 in combination with pembrolizumab (NCT05127590). Citation Format: Timothy A. Yap, Andres Cervantes, Gerald S. Falchook, Manish R. Patel, Dejan Juric, Saiama N. Waqar, Erin L. Schenk, Geoffrey Shapiro, Valentina Boni, Cesar A. Perez, Barbara Burtness, Yana G. Najjar, Fabricio Racca, Katerin Rojas, Kristy Kuplast-Barr, Kristen McEachern, Manoj Samant, Viviana Bozón, Sudha Parasuraman, Melissa Johnson. First-in-class first-in-human phase 1 trial and translational study of the mono(ADP-ribose) polymerase-7 (PARP7) inhibitor RBN-2397 in patients with selected advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT109.

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.

BackgroundPARP7 is a mono-ART that is upregulated in response to cellular stress (e.g., viral infection, cigarette smoke), and suppresses the Type I interferon (IFN) response following cytosolic nucleic acid sensing. RBN-2397 is a first-in-class PARP7 inhibitor, inducing cancer cell autonomous and immune stimulatory effects in preclinical models through enhanced Type I IFN signaling in cancer cells. Moreover, RBN-2397 induces CD8 T cell-dependent tumor-specific immune memory in an immunocompetent mouse cancer model.1 RBN-2397 is currently being tested in an ongoing Phase I clinical study (NCT04053673).2 Here we aimed to compare biomarker results from preclinical models and patient samples.MethodsIn preclinical models, interferon-stimulated gene (ISG) expression was assessed by qPCR, NanoString, or ELISA. Plasma CXCL10 from patients was measured by MSD while ISG expression in PBMCs was measured by NanoString. Baseline and on-treatment patient tumor biopsies were analyzed by NanoString, CD8/GZMB IHC, and MIBI-TOF to characterize immune changes in the tumor microenvironment.ResultsRBN-2397 potently restored tumoral Type I IFN signaling in preclinical models as demonstrated by increases in ISGs, namely CXCL10, which were not observed in non-tumor tissue (e.g. spleen, PBMCs). In peripheral blood from patients treated with RBN-2397, neither plasma nor PBMC CXCL10 increased more than 2-fold over baseline. Expression of 42 ISGs was not consistently induced in a dose-dependent manner in PBMCs. However, in tumor types of interest (e.g. cancers of the upper aerodigestive tract), CXCL10 expression increased 1.5 to 8-fold, with similar effects observed for a subset of ISGs in 5 evaluable paired biopsy samples.Confirming preclinical studies [1], up to 8-fold increases in CD8 T cell infiltration along with induction of granzyme B expression were observed in 4 of 5 paired patient tumor biopsies by immunohistochemistry. Using the MIBI-TOF technology, we observed up to 50-fold increases in intratumoral activated T cells as well as monocytes and M1 macrophages, most strikingly in two NSCLC patients.ConclusionsInhibition of PARP7 with RBN-2397 restores tumor-intrinsic Type I IFN signaling in preclinical models leading to enhanced adaptive immunity, resulting in CD8 T cell-dependent durable tumor regressions. These observations are mirrored in samples from patients treated with RBN-2397 in that pharmacodynamic effects of RBN-2397 were preferentially observed in tumor tissue relative to the periphery, including an increase in immune infiltration into the tumor microenvironment. These data provide evidence for induction of an adaptive immune response and confirm the tumor-intrinsic, immunomodulatory mechanism of action of RBN-2397 in patients.ReferencesGozgit, et al. PARP7 negatively regulates the type I interferon response in cancer cells and its inhibition triggers antitumor immunity. Cancer Cell 2021; In press.Falchook, et al. A first-in-human phase 1 study of a novel PARP7 inhibitor RBN-2397 in patients with advanced solid tumors. ASCO 2021; oral presentation.

Background: PARP7 is a mono-ART that is upregulated in response to cellular stress (e.g., viral infection, cigarette smoke), and suppresses the Type I interferon (IFN) response following cytosolic nucleic acid sensing. RBN-2397 is a first-in-class PARP7 inhibitor, inducing cancer cell autonomous and immune stimulatory effects in preclinical models through enhanced Type I IFN signaling in cancer cells. Moreover, RBN-2397 induces CD8 T cell-dependent tumor-specific immune memory in an immunocompetent mouse cancer model [1]. RBN-2397 is currently being tested in an ongoing Phase I clinical study (NCT04053673) [2]. Here we present evidence of proof of mechanism in the paired biopsies of tumors from Phase 1 patients. Methods: Plasma CXCL10 from patients was measured by MSD while ISG expression in PBMCs was measured by NanoString. Baseline and on-treatment patient tumor biopsies were analyzed by NanoString, CD8/GZMB IHC, and MIBI-TOF to characterize immune changes in the tumor microenvironment. Results: In peripheral blood from patients treated with RBN-2397, neither plasma nor PBMC CXCL10 increased more than 2-fold over baseline. Expression of 42 ISGs was not consistently induced in a dose-dependent manner in PBMCs. However, in tumor types of interest (e.g., cancers of the upper aerodigestive tract), CXCL10 expression increased, with similar effects observed for a subset of ISGs in multiple evaluable paired biopsy samples. Confirming preclinical studies [1], increases in CD8 T cell infiltration along with induction of granzyme B expression were observed in several evaluable paired patient tumor biopsies by immunohistochemistry. Using the MIBI-TOF technology, we observed up to 50-fold increases in intratumoral activated T cells as well as monocytes and M1 macrophages, most strikingly in two NSCLC patients. Conclusions: In patients treated with RBN-2397 pharmacodynamic effects were preferentially observed in tumor tissue relative to the periphery, including an increase in immune infiltration into the tumor microenvironment. These data provide evidence for induction of an adaptive immune response and confirm the tumor-intrinsic, immunomodulatory mechanism of action of RBN-2397 in patients. References: 1. Gozgit et al. PARP7 negatively regulates the Type I interferon response in cancer cells and its inhibition triggers antitumor immunity. Cancer Cell. 2021 2. Falchook et al. A First-In-Human Phase 1 Study of a Novel PARP7 Inhibitor RBN-2397 in Patients with Advanced Solid Tumors. ASCO 2021 oral presentation Citation Format: Kristy Kuplast-Barr, Melissa L. Johnson, Manish R. Patel, Timothy A. Yap, Gerald S. Falchook, Patricia LoRusso, Ryan Abo, Chang Liu, Erika L. Manyak, Lisa Cleary, Viviana Bozon, Sudha Parasuraman, Heike Keilhack, Kristen McEachern. RBN-2397, a novel, potent, and selective PARP7 inhibitor, induces tumor-intrinsic type I interferon responses and adaptive immunity in patient tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1836.

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.

3000 Background: Targeting cytosolic nucleic acid sensing pathways and the Type I interferon (IFN) response is an emerging therapeutic strategy in oncology. PARP7 is a member of the monoPARP class of enzymes and a newly identified negative regulator of nucleic acid sensing in tumor cells. PARP7 expression is increased by cellular stress and aromatic hydrocarbons, and the PARP7 gene is amplified in multiple cancers. RBN-2397 is a potent, selective inhibitor of PARP7. In preclinical models, RBN-2397 restored Type I IFN signaling in tumors, caused complete tumor regressions, and induced adaptive immunity. Methods: Patients (pts) with advanced solid tumors were treated with RBN-2397 on either a continuous or 14-of-21-day intermittent schedule using a 3+3 dose escalation design. Primary objective: establish MTD and/or RP2D. Secondary obj.: safety, activity, PK of unmicronized/micronized tablets. Exploratory obj.: Pd. Results: As of 4 January 2021, 47 pts were treated: 25 pts in the intermittent schedule (25 to 500 mg BID) and 22 patients in the continuous schedule (100 to 400 mg BID). The most frequent RBN-2397-related AEs (all grades) were dysgeusia (26%), decreased appetite (13%), fatigue (11%), and diarrhea (11%). Gr 3/4 RBN-2397-related AEs all occurred in 7 pts (15%) at doses ≥ 200 mg: diarrhea (2 pts, 4%), increased ALT, AST, and bilirubin (1 pt, 2%), and fatigue, anemia, neutropenia, and thrombocytopenia in 1 pt (2%) each. The 2 DLTs were Gr 3 febrile neutropenia (400 mg continuous schedule) and Gr 4 increase in ALT/AST (500 mg intermittent schedule). Plasma exposures generally increased dose dependently with the majority at or above the projected efficacious range based on animal studies. All evaluable baseline tumor biopsies showed evidence of PARP7 expression as measured by mRNA in situ hybridization (n = 11; Median tumor H score: 128). In 5 evaluable tumor biopsy pairs, increases in interferon-stimulated gene expression were observed post RBN-2397, consistent with activation of Type I IFN. CXCL10 mRNA increased in all evaluable on-treatment biopsies (1.5 to 8-fold). Several on-treatment biopsies showed enrichment for immune response gene sets that was accompanied by an increase in CD8+ T cells and Granzyme B expression, evidence for induction of an adaptive immune response post RBN-2397. This increase in immune response related genes and CD8+ T cells was observed in a pt with metastatic squamous NSCLC who has been on study for 16+ months. 1 pt with HR+, HER2- breast cancer achieved a confirmed PR at 100 mg and 8 pts had SD for ≥18 weeks (RECIST 1.1). Conclusions: To date, RBN-2397 is well tolerated and demonstrates dose dependent increases in plasma exposures, evidence of target inhibition, and preliminary signs of clinical activity. Determination of MTD/RP2D is imminent and study expansion is planned to evaluate safety and efficacy in squamous NSCLC, HNSCC, HR+ breast cancer, and PARP7 amplified tumors. Clinical trial information: NCT04053673.

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.

// Alyssa L. Kennedy 1, 2, * , Mounica Vallurupalli 1, 3, * , Liying Chen 1, * , Brian Crompton 1 , Glenn Cowley 4 , Francisca Vazquez 4 , Barbara A. Weir 4 , Aviad Tsherniak 4 , Sudha Parasuraman 5 , Sunkyu Kim 5 , Gabriela Alexe 1, 4, 6 , Kimberly Stegmaier 1, 4 1 Department of Pediatric Oncology, Dana-Farber Cancer Institute and Boston Children’s Hospital, Boston, Massachusetts, USA 2 Boston Combined Residency Program in Pediatrics, Boston, Massachusetts, USA 3 Department of Internal Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, USA 4 Broad Institute, Cambridge, Massachusetts, USA 5 Novartis Institute for Biomedical Research, Cambridge, Massachusetts, USA 6 Bioinformatics Graduate Program, Boston University, Boston, Massachusetts, USA * These authors have contributed equally to this work Correspondence to: Kimberly Stegmaier, e-mail: kimberly_stegmaier@dfci.harvard.edu Keywords: CDK4/6 inhibitor, cyclin D1, epigenetics, Ewing sarcoma, sarcoma/soft-tissue malignancies Received: June 29, 2015 Accepted: August 07, 2015 Published: August 18, 2015 ABSTRACT 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.

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.

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.

Background: WHIM (Warts, Hypogammaglobulinemia, Infections, Myelokathexis) Syndrome is a serious, ultrarare genetic disorder caused by a gain-of-function mutation in CXCR4 that causes profound neutropenia and lymphopenia associated with increased rates of bacterial and viral infections. Long-term sequelae include hearing loss, bronchiectasis, and HPV-associated malignancies. The cancer risk in WHIM patients is estimated at 30% by age 40. There is currently no treatment that addresses the underlying mechanism of disease. G-CSF increases neutrophil counts but does not appear to reduce infection rates; use of parenteral gamma globulin has had mixed reports of benefit, but no controlled trials have been reported; Plerixafor, a CXCR4 antagonist, has been shown to increase leukocyte counts and reduce infection rates when absolute neutrophil counts (ANC)>600 mm-3 and absolute lymphocyte counts (ALC)>1000 mm-3, but is a parenteral agent that must be administered twice daily. X4P-001 is an orally available, allosteric inhibitor of CXCR4 that is being developed to treat WHIM. We report here the PK/PD data from the Phase 2 portion of Phase 2/3 trial X4P-001 MKKA (NCT03005327) in WHIM patients that led to selection of the dose for Phase 3 development. Methods: Study X4P-001 MKKA is a Phase 2/3 study. The primary objective of Ph2 portion was to assess the dose required to achieve a consistent increase in circulating neutrophils and lymphocytes. Adult patients with WHIM syndrome, with documented WHIM-associated genotype, and either ANC Results: Eight patients were enrolled and were evaluable for efficacy. 6 of 8 were female, and the mean (SD) age was 35.5 (13.37). Two patients started treatment with 50 mg, then received, 100, 150, 300 and 400 mg; 2 started at 100 and then received 200 and 300 mg; 2 started at 200 mg; 1 escalated to 300 and 400 mg while the other terminated after 1 week due to an adverse event (AE). Two started at 300 mg and did not escalate. Doses of at least 300 mg/day were needed to achieve success criteria for ANC, while at doses ≥100 mg/day, 50-100% met success criteria for ALC. (Figure 1) Two patients discontinued: 1 due to an AE of grade 1 rash, and 1 voluntarily withdrew. No serious AEs were reported. One patient had unrelated cholecystitis (grade 3). All other AEs were grade 1 or 2. Conclusions: Treatment of WHIM patients with X4P-001 results in meaningful increases in ANC at doses ≥300 mg, and in ALC at doses ≥100 mg per day for at least 5 weeks. These doses are anticipated to be associated with clinically meaningful outcomes in terms of infections and warts. X4P-001 appeared to be safe and well-tolerated at doses of 50-400 mg per day.4 Disclosures Dale: Athelas, Inc.: Equity Ownership; Amgen: Consultancy, Research Funding; Sanofi-Aventi: Consultancy, Honoraria; Cellerant: Other: Scientific Advisory Board; Hospira: Consultancy; Prolong: Consultancy; Beheringer-Ingelheim: Consultancy; Coherus: Consultancy. Hartmann:Cetara: Employment; X4P Pharmaceuticals: Consultancy. Brown:Certara: Employment; X4P Pharmaceuticals: Consultancy. Ebrahim:X4Pharmaceuticals: Employment. Gorelick:X4 Pharma: Consultancy; PIN Pharma: Consultancy; Shire: Consultancy; NGN Capital: Consultancy, Other: Venture partner; IntraBio: Consultancy; Zymo Consulting Group LLC: Employment.

Background: The CXCR4/CXCL12 pathway plays a central role in the trafficking of key immune cells in the tumor microenvironment (TME). X4P-001 is an oral, selective, allosteric CXCR4 inhibitor. We hypothesize that the disruption of CXCR4/CXCL12 signaling by X4P-001 will favor an improved response to checkpoint inhibitors by modulating the immune cell profile within the TME and increasing CD8+ T cell infiltration. A biomarker-driven phase 1b clinical study is being conducted in melanoma patients to test this hypothesis (NCT02823405). Materials and Methods: The primary objectives for the study are to evaluate the safety and tolerability of X4P-001 as a single agent and in combination with pembrolizumab in patients (pts) with metastatic melanoma, and to characterize the effects of X4P-001 alone and in combination with pembrolizumab on tumor immune cell infiltrates. Serial biopsies of cutaneous or subcutaneous melanoma lesions, peripheral blood mononuclear cells (PBMCs), and serum samples were collected pre-dose, after 3 weeks of X4P-001 treatment, and after 6 weeks of combination treatment. Biopsies were assessed by immunohistochemistry (IHC) and multiplexed immunofluorescence (mIF) for multiple markers, including CD3, CD8, FoxP3, PD-L1 and Granzyme B, and by NanoString® analysis for changes in gene expression. PBMCs were analyzed by flow cytometry for both lymphoid and myeloid cells. In addition, multiple serum markers will be assessed using the multi-analyte profile (MAP) platform. Results: As of September 15, 2017, 13 pts have been enrolled, and 11 have completed the study. The median age was 73 years (range 53-90). Of the evaluable pairs of biopsies, X4P-001 treatment alone increased CD8+ T cells, increased granzyme B signal, increased antigen-presenting machinery such as HLA-DR, and increased IFN-gamma gene expression signature scores in the TME. These biomarker responses were further enhanced when X4P-001 was combined with pembrolizumab. X4P-001 was well tolerated. AEs assessed as related to either X4P-001 or pembrolizumab at any time were diarrhea, maculopapular rash, fatigue, chills, and acute kidney injury. These data, along with additional biomarker measurements, will be presented. Conclusions: Evidence of enhanced immune cell infiltration and activation is observed in the TME with X4P-001 treatment alone. Increased IFN-gamma gene expression signature scores after single-agent X4P-001 treatment support the use of X4P-001 to increase the likelihood of a response when combined with anti-PD-1 therapy. X4P-001 as a single agent and in combination with pembrolizumab is generally safe and well tolerated. Further in-depth biomarker analysis is ongoing as enrollment nears completion. Citation Format: Robert H. Andtbacka, Robert H. Pierce, Jean S. Campbell, Melinda Yushak, Mohammed Milhem, Merrick Ross, Kenneth Grossmann, Kam Sprott, Eleni Tsiroyanni, Katie Niland, Lu Gan, Sudha Parasuraman, Yan Wang. X4P-001, an orally bioavailable CXCR4 antagonist, enhances immune cell infiltration and activation in the tumor microenvironment of melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 613.

Background: WHIM syndrome (WHIMs; Warts, Hypogammaglobulinemia, Infections, Myelokathexis) is a rare autosomal dominant immunodeficiency disease attributable to mutations in CXCR4 . Most patients have severe neutropenia and lymphocytopenia with total white blood cell counts (WBC) Methods: We have begun the phase 2, dose-titration portion of a phase 2/3 study of a novel, orally bioavailable, selective, CXCR4 antagonist, X4P-001, in adult patients with genetically confirmed WHIMs to evaluate safety and tolerability of X4P-001 and determine the dose for a phase 3 study. All patients were required to be off chronic immunoglobulin and/or G-CSF treatment while on study. Patients receive increasing doses of X4P-001 ranging from 50 mg to 300 mg orally once daily with periodic monitoring of serial blood counts and intra-patient dose escalation is based on 24-hour serial area-under-the-curve (AUC) measurements of absolute neutrophil counts (ANC) and absolute lymphocyte counts (ALC) with prespecified thresholds. Results: As of July 10, 2017, 4 patients (2 females, 2 males; age range 19 to 57 years; 3 with R334X and 1 with E343X mutation) have been enrolled. The study entry screening WBC was 0.775 x 109/L +/-0.16 (mean +/- SEM); ANC was 0.125 x 109/L +/- 0.027; and ALC was 0.588 x 109/L +/- 0.155. All patients had mild hypogammaglobulinemia; the mean levels were: Immunoglobulin G 766 +/- 130 (SEM), IgA 50 +/- 17, IgM 74 +/- 13. In the 6 months prior to study entry, these adult patients had up to 6 episodes of infections, primarily upper respiratory and skin infections. Patients 1 and 2 have escalated through 50 mg/day and 100 mg/day to 150 mg/day over a total exposure period of 169 days. Patients 3 and 4 have escalated from 100 mg/day to 200 mg/day with an exposure period of 62 and 54 days, respectively. All patients have demonstrated a dose-dependent increase in ANC and ALC from screening values, with ALC increasing in greater proportion than ANC. At the 100 mg dose level, the pre-dose WBC was 1.24 x 109/L +/- 0.469 (mean +/- SEM) with peak levels of 2.8 x 109/L +/- 0.721 (increase=2.3 fold), the pre-dose ANC was 0.385 x 109/L +/- 0.178) with peak levels of 0.58 x 109/L +/- 0.202 (increase=1.5 fold) and pre-dose ALC was 0.728 x 109/L +/- 0.276 with peak levels of 2.143 x 109/L +/-0.513 (increase=2.9 fold). The increases in the pre-dose levels of both neutrophils and lymphocytes above the study entry screening values after 1-3 months on treatment suggest a continuing effect of daily exposure to this drug. However, the ANC and ALC responses thus far are below the targeted AUC for ANC and ALC, so dose escalation continues. Thus far, X4P-001 has been well tolerated and the most common treatment-related adverse events are mild dyspepsia and dry eyes. Patients have not required antibiotic treatment for infections during the cumulative 15 months on X4P-001, except for Patient 1 who had an infection at the start of the study. Conclusion: Preliminary data suggests X4P-001 is a promising oral agent for treating WHIM syndrome. Disclosures Dale: Sanofi Aventis: Consultancy, Editor, Current Opinions in Hematology, Honoraria; Cellerant: Membership on an entity's Board of Directors or advisory committees; Genzyme (now owned by Sanofi-Aventis): Consultancy, Patents & Royalties, Research Funding; Genkyotex: Other: DSMB (work completed 6/2015); Hospira: Consultancy; Prolong: Consultancy; Boheringer-Ingelheim: Consultancy; Coherus: Consultancy; Omeros: Other: DSMB; Shire: Other: Independent Review Board; X4Pharma: Research Funding; Philips: Research Funding; Wolter Kluwer: Other: Editor, Current Opinions in Hematology; WedMD/Medscape: Membership on an entity's Board of Directors or advisory committees; National Institutes of Health: Research Funding; University of Washington: Employment, Research Funding; American College of Physicians: Other: Editor and author; GlaxoSmithKline: Equity Ownership; Johnson&Johnson: Equity Ownership; Amgen: Consultancy, Research Funding. Johnson: X4 Pharmaceuticals: Employment. Gan: X4 Pharmaceuticals: Employment, Equity Ownership. Parasuraman: X4 Pharmaceuticals: Employment, Equity Ownership.

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.

Clear cell sarcoma is a rare soft tissue neoplasm whose clinical behavior and outcome has not been previously characterized. This study reviewed the clinical characteristics and outcome of all children with clear cell sarcoma of the soft tissues who were treated at St. Jude Children's Research Hospital from March 1962 through August 1998. Of 225 children with nonrhabdomyosarcomatous soft tissue sarcomas, 5 (2.2%) were diagnosed with clear cell sarcoma. Median age at diagnosis was 15 years 3 months. Primary sites included the extremities (n = 3), chest wall (n = 1), and abdomen (n = 1). At diagnosis 3 patients had localized disease. Following surgical resection (n = 3), radiotherapy (n = 2), and chemotherapy (n = 1) all three survive disease-free 10, 11, and 90 months after diagnosis, respectively. The remaining two patients with metastatic disease at diagnosis died 21 days and 9 months after diagnosis. Clear cell sarcoma of the soft tissues is rare in pediatrics. Complete surgical resection with negative margins is the most effective treatment for this disease. Patients with metastatic disease are candidates for multiinstitutional chemotherapy trials.

2528Background: The Signature program comprises a series of 8 tissue-agnostic, mutation-specific, signal-seeking protocols without predetermined study sites, thereby bringing the protocol to the pt. Pts included in the ribociclib (LEE011) protocol had CDK4/6 pathway aberrations, identified via standard-of-care physician-directed profiling. Separate ribociclib phase 3 studies in breast cancer are ongoing. Methods: Pts with measurable advanced malignancies and no established standard therapy options were eligible. The primary objective was assessment of clinical benefit (CB; CR + PR + SD) at wk 16 by local investigator. Ribociclib was given orally (600 mg QD; 3 wk on, 1 wk off). Statistical design adaptively clustered pts into cohorts for independent analysis of early futility or efficacy. GMP of pt tumors was performed centrally for post hoc eligibility confirmation. Results: As of 28 Aug 2015, 106 pts were enrolled across 31 tumor types. Median age was 63 years (range, 19-86 years), 53% were women, and me...

In the Signature Program, patients with advanced solid and hematologic cancers without other standard treatment options are enrolled in 1 of 8 tissue-agnostic, mutation-specific protocols. With no predetermined study sites, the program is able to bring the protocol to the patient through local enrollment via physician-directed genomic profiling of tumors. The primary endpoint of each study is clinical benefit, including complete response, partial response, or stable disease [SD], at 16 weeks by investigator assessment using Response Evaluation Criteria In Solid Tumors (RECIST) 1.1 or appropriate hematologic criteria. This novel design allows rapid matching of patients to a relevant targeted therapy. Dovitinib, a tyrosine kinase inhibitor with activity against multiple receptor tyrosine kinases, is currently in clinical development. Eighty patients were accrued in the dovitinib (TKI258) protocol from May 2013 to January 2015. Here, we describe a head and neck cancer subset of this population, including adenoid cystic carcinoma (ADC; n = 6), head and neck squamous cell carcinoma (HNSCC; n = 5), and salivary gland cancer (n = 1). The median age was 62 years, and patients had a median of 2 prior lines of therapy; 69% of patients were male, 85% were Caucasian, and 31% and 69% had an Eastern Cooperative Oncology Group performance status of 0 and 1, respectively. Patients met mutational inclusion criteria, with mutations in PDGFRα/β, c-KIT, VEGFR2, FGFR1/2, and RET. There were no confirmed responses; however, 5 patients had SD on study. Of the 5 patients with SD, 4 had clinical benefit at 16 weeks (1 patient with SD at 8 weeks discontinued before 16 weeks). Consistent with other studies of dovitinib monotherapy, gastrointestinal adverse events (fatigue [69%], nausea [69%], diarrhea [54%], and vomiting [54%]) were the most common. In addition, pretreatment tissue biopsies from all patients were analyzed by a large multigene next-generation sequencing assay. Results to date indicate that the ADC cohort has a lower mutational load and fewer prior therapies than the HNSCC cohort. Further analysis of a correlation between clinical benefit and specific mutational profile is ongoing. Citation Format: Sarina A. Piha-Paul, James A. Knost, Luis E. Raez, Allen L. Cohn, Hussein A. Tawbi, Sudha Parasuraman, Barinder P. Kang, Renata M. Matys, Eric D. Slosberg. Outcomes and genomic mutational profiling results in patients with cancers of the head and neck treated with dovitinib in the Signature Program. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B22.

The Signature program comprises a series of 8 tissue-agnostic, mutation-specific protocols without predetermined study sites. Eligible patients have advanced solid and hematologic cancers without remaining standard therapeutic options. Clinical benefit (stable disease [SD], partial response [PR], or complete response [CR]) at 16 weeks as assessed by the investigator (Response Evaluation Criteria In Solid Tumors [RECIST] version 1.1 or appropriate hematologic criteria) is the primary endpoint of each study. Through local enrollment via physician-directed genetic profiling, patients can be rapidly matched with a relevant targeted-treatment protocol, effectively bringing the protocol to the patient. One protocol involves buparlisib (BKM120), a highly specific and potent oral pan-class I inhibitor of phosphatidylinositol 3-kinase (PI3K) currently in clinical development. A total of 146 patients were accrued in the buparlisib protocol in the Signature program from March 2013 to January 2015. Here, we describe a gynecologic cancer subset of this population, including patients with cervical (n = 11), ovarian (n = 12), uterine (n = 3), and vaginal cancer (n = 4). The median age was 61 years, and patients had a median of 4 lines of prior therapy; 83% of patients were Caucasian, and 47% and 53% had an Eastern Cooperative Oncology Group performance status of 0 and 1, respectively. All patients met mutational inclusion criteria, including 47% with PIK3CA mutations, 20% with PTEN loss (immunohistochemistry), 17% with PTEN mutation or loss (DNA), and 17% with PIK3CA amplification. Best responses of SD, PR, and CR at any time were observed in 13, 1, and 1 patients, respectively; of these, 7 patients had clinical benefit (SD, n = 6; PR, n = 1) at 16 weeks. Tolerability was consistent with that in other studies of buparlisib monotherapy: the most common adverse events (≥ 25%) were diarrhea (33%), nausea (33%), fatigue (33%), and hyperglycemia (30%). A large multigene next-generation sequencing assay was performed on pretreatment tissue biopsies from all patients. Preliminary findings indicate that among buparlisib-treated patients with gynecologic cancers in this analysis, those with cervical cancer had more gene amplifications and fewer gene losses and those with ovarian cancer had more p53 deregulations and fewer PIK3CA mutations. Although no clear correlation between clinical benefit and specific mutational profile has been observed, further analysis is ongoing. Citation Format: Sarina A. Piha-Paul, Daniel L. Spitz, J. Thaddeus Beck, Fadi S. Braiteh, Joseph Buscema, Richard Frank, Sudha Parasuraman, Barinder P. Kang, Renata M. Matys, Eric D. Slosberg. Outcomes and genomic mutation profiling results in a subset of patients with gynecologic cancers treated with buparlisib in the Signature Program. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A53.

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/m2 on days 1, 8, 15, and 22, cycles one to five; bendamustine 50, 70, or 90 mg/m2 IV over a 60-minute infusion on days 1 and 2, cycles one to five; and rituximab 375 mg/m2 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/m2 dose level was expanded for the efficacy assessment, and a total of 63 patients received bendamustine 90 mg/m2. 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.

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.

Case Presentation : A 29-year-old woman presented to the emergency department with complaints of pleuritic chest pain, fever, and left ankle swelling and tenderness. Cardiac examination was normal except for tachycardia. A chest computed tomography scan with contrast demonstrated extensive bilateral pulmonary emboli. Thirteen days previously, an intoxicated driver with multiple prior convictions for driving under the influence of alcohol crashed head-on into her car at a high speed. She was 8 months’ pregnant and suffered the loss of the child. She spent 7 days in the hospital and underwent cesarean section, exploratory laparotomy, and splenectomy. No preoperative pharmacological prophylaxis against venous thromboembolism (VTE) was administered. VTE, which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is an important and common complication of general surgery. A new era in the postoperative management of surgical patients began in 1975 when the effectiveness of low-dose heparin in preventing postoperative DVT and PE was established by the pivotal International Multicenter Trial.1 The dose was 5000 U subcutaneously every 8 hours, with the first injection administered 2 hours before the skin incision. Compared with control, the incidence of DVT in patients receiving heparin decreased from 24.6% to 7.7%. Similarly, the incidence of autopsy-proven PE was reduced 8-fold. The results of this trial introduced and validated the concept of using low-dose heparin to prevent postoperative VTE. This trial revolutionized surgical practice. By 1994, 90% of North American general surgeons reported the routine use of thromboprophylaxis.2 Most postoperative DVT originates in the deep calf veins, primarily within the valve cusps. Most thrombi remain confined to the calf. Propagation into the proximal veins increases the risk of PE. Symptoms and signs of postoperative VTE such as mild hypoxia or low-grade fever are frequently nonspecific. Moreover, clinical manifestations of postoperative VTE may not occur until …

106 Background: Here we describe 8 ongoing single agent clinical protocols under Novartis’ “Signature” program involving buparlisib (BKM120, PI3Ki), dovitinib (TKI258, multikinase inhibitor), binim...

Case 1: A 4-year-old boy with acute lymphoblastic leukemia (ALL) and disseminated candidiasis was found to have a right atrial thrombus on a routine imaging study. He had a central venous catheter (CVC) and was receiving chemotherapy that contained asparaginase. Thrombophilia workup was negative. Case 2: A 17-year-old girl presented to the emergency department with a 3-week history of left-sided chest pain and shortness of breath. She had been taking high-dose estrogen therapy for congenital tall stature. D-dimer was positive. Chest CT revealed multiple small pulmonary emboli and infarcts. Lower-extremity venous ultrasound was negative for deep vein thrombosis, and echocardiography showed normal right ventricular function. Thrombophilia workup was negative. Decreased capacity to generate thrombin, increased capacity of α2-macroglobulin to inhibit thrombin, and enhanced antithrombotic potential by the vessel wall appear to contribute to the low incidence of venous thromboembolism (VTE) during childhood. Nevertheless, VTE is being diagnosed more frequently in children. The annual incidence is 0.07 to 0.14 per 10 000 children, or 5.3 per 10 000 hospital admissions of children, and 24 per 10 000 admissions to neonatal intensive care units.1–3 The highest incidence is during the neonatal period, followed by another peak in adolescence. Patients in neonatal and pediatric intensive care units and oncology patients are particularly at high risk. Teenage girls have twice the rate of VTE as do teenage boys. This appears to be due to the use of oral contraceptives and pregnancy.4 ### Risk Factors Idiopathic VTE in the pediatric population is relatively infrequent and is almost always associated with an underlying disease or risk factor. Both congenital and acquired conditions contribute to the development of thrombosis. More than 90% of children with VTE will have ≥2 predisposing factors (Figure). Figure 1. Risk factors for childhood VTE. #### Acquired Conditions The presence of a CVC is the …

Aim: SMARCB1 mutations are observed in the majority of malignant rhabdoid tumors (MRTs) rendering them dependent on cyclin D1 (CCND1) for genesis and survival. Genetic aberrations in CCND1 and CDK4 are frequent in neuroblastoma cell lines. LEE011 is an orally bioavailable, selective inhibitor of CDK4/6 that has demonstrated tumor growth inhibition in MRT and neuroblastoma preclinical models. In this Phase I study, LEE011 is being investigated in patients (pts) with MRT, neuroblastoma, or other cancers with documented cyclin D–CDK4/6–INK4a–Rb pathway aberrations. Methods: Pts (aged 1–21 years) receive escalating once-daily doses of LEE011 on a 3-weeks-on, 1-week-off schedule. Dose escalation is guided by a Bayesian Logistic Regression Model with overdose control principle and real-time PK. Primary objective: MTD and/or recommended dose for expansion (RDE) determination. Secondary objectives: safety, PK, and efficacy. Results: As of April 8, 2014, 22 pts (11 MRT [9 primary central nervous system (CNS) and 2 extra-CNS], 10 neuroblastoma, and 1 CDK4-amplified alveolar rhabdomyosarcoma) have received LEE011: 5 at 280 mg/m2; 9 at 350 mg/m2; 8 at 470 mg/m2. The median age was 5 (1–20) years. Two DLTs were reported: 1 Grade (G)3 fatigue at 280 mg/m2; 1 G4 thrombocytopenia at 470 mg/m2. Study drug-related all-grade AEs (N = 20; ≥20%) included neutropenia (75%), leukopenia (65%), anemia (40%), thrombocytopenia (40%), lymphopenia (35%), vomiting (25%), decreased appetite (20%), electrocardiogram QT prolongation (20%), fatigue (20%), and nausea (20%). G3/4 AEs (>10%) included neutropenia (70%), leukopenia (35%), thrombocytopenia (25%), and lymphopenia (15%). Preliminary PK analysis showed that exposure following 280 and 350 mg/m2 is comparable to equivalent doses in adults and slightly higher at 470 mg/m2. LEE011 is rapidly absorbed with Tmax ranging from 1–4 hrs (median: 2–3 hrs) across dose levels. To date, best response obtained is stable disease. Conclusions: LEE011 demonstrated an acceptable safety profile and dose-dependent PK. Enrollment continues to identify the MTD/RDE and there will be expansion arms for pts with MRT or neuroblastoma at the RDE. Disclosure: S.G. Dubois: is the site PI for industry sponsored clinical trials (Merck and Novartis). He is also the study chair for a trial funded by Millennium; A. Marabelle: is a member of Advisory Boards for Novartis, BMS, Roche/Genentech, Celgene, Bayer, and Flexus Biotech; S. Modak: has served on an advisory board for Novartis for an unrelated drug; R. Kan: is an employee of and holds shares in Novartis Pharma AG A. Matano: is an employee of Novartis Pharma AG; S.G. Bhansali: is an employee of and holds shares in Novartis Pharmaceuticals Corporation; S. Parasuraman: is an employee of and holds shares in Novartis Pharma AG.All other authors have declared no conflicts of interest.