Francois Wilhelm

Treatment of higher risk myelodysplastic syndrome patients unresponsive to hypomethylating agents with ON 01910.Na

In a Phase I/II clinical trial, 13 higher risk red blood cell-dependent myelodysplastic syndrome (MDS) patients unresponsive to hypomethylating therapy were treated with the multikinase inhibitor ON 01910.Na. Responses occurred in all morphologic, prognostic risk and cytogenetic subgroups, including four patients with marrow complete responses among eight with stable disease, associated with good drug tolerance. In a subset of patients, a novel nanoscale immunoassay showed substantially decreased AKT2 phosphorylation in CD34+ marrow cells from patients responding to therapy but not those who progressed on therapy. These data demonstrate encouraging efficacy and drug tolerance with ON 01910.Na treatment of higher risk MDS patients.

Rigosertib versus best supportive care for patients with high-risk myelodysplastic syndromes after failure of hypomethylating drugs (ONTIME): a randomised, controlled, phase 3 trial

BACKGROUND Hypomethylating drugs are the standard treatment for patients with high-risk myelodysplastic syndromes. Survival is poor after failure of these drugs; there is no approved second-line therapy. We compared the overall survival of patients receiving rigosertib and best supportive care with that of patients receiving best supportive care only in patients with myelodysplastic syndromes with excess blasts after failure of azacitidine or decitabine treatment. METHODS We did this randomised controlled trial at 74 hospitals and university medical centres in the USA and Europe. We enrolled patients with diagnosis of refractory anaemia with excess blasts (RAEB)-1, RAEB-2, RAEB-t, or chronic myelomonocytic leukaemia based on local site assessment, and treatment failure with a hypomethylating drug in the past 2 years. Patients were randomly assigned (2:1) to receive rigosertib 1800 mg per 24 h via 72-h continuous intravenous infusion administered every other week or best supportive care with or without low-dose cytarabine. Randomisation was stratified by pretreatment bone marrow blast percentage. Neither patients nor investigators were masked to treatment assignment. The primary outcome was overall survival in the intention-to-treat population. This study is registered with ClinicalTrials.gov, NCT01241500. FINDINGS From Dec 13, 2010, to Aug 15, 2013, we enrolled 299 patients: 199 assigned to rigosertib, 100 assigned to best supportive care. Median follow-up was 19·5 months (IQR 11·9-27·3). As of Feb 1, 2014, median overall survival was 8·2 months (95% CI 6·1-10·1) in the rigosertib group and 5·9 months (4·1-9·3) in the best supportive care group (hazard ratio 0·87, 95% CI 0·67-1·14; p=0·33). The most common grade 3 or higher adverse events were anaemia (34 [18%] of 184 patients in the rigosertib group vs seven [8%] of 91 patients in the best supportive care group), thrombocytopenia (35 [19%] vs six [7%]), neutropenia (31 [17%] vs seven [8%]), febrile neutropenia (22 [12%] vs ten [11%]), and pneumonia (22 [12%] vs ten [11%]). 41 (22%) of 184 patients in the rigosertib group and 30 (33%) of 91 patients in the best supportive care group died due to adverse events and three deaths were attributed to rigosertib treatment. INTERPRETATION Rigosertib did not significantly improve overall survival compared with best supportive care. A randomised phase 3 trial of rigosertib (NCT 02562443) is underway in specific subgroups of patients deemed to be at high risk, including patients with very high risk per the Revised International Prognostic Scoring System criteria. FUNDING Onconova Therapeutics, Leukemia & Lymphoma Society.

Phase I clinical trial of oral rigosertib in patients with myelodysplastic syndromes.

The multi‐kinase inhibitor rigosertib (ON 01910.Na) induces mitotic arrest and apoptosis in myeloblasts, while sparing normal cells. The purpose of this study was to determine the pharmacokinetic profile, maximum‐tolerated dose (MTD), safety, and clinical activity of an oral formulation of rigosertib in patients with myelodysplastic syndromes (MDS). For pharmacokinetic studies, patients received rigosertib in single escalating weekly doses. To determine the MTD, patient cohorts received escalating doses of rigosertib twice daily for 14 d of a 21‐d cycle. Overall, 37 patients were treated. Rigosertib exposure increased with escalating oral doses. Mean absolute oral bioavailability ranged from 13·9% (fed) to 34·8% (fasting) in 12 patients treated at the 560 mg b.i.d. dose level. Dose‐limiting toxicity (grade 3 dysuria and shortness of breath) occurred at the 700 mg b.i.d. dose. Five patients experienced grade 3 non‐haematological toxicity, including symptoms of urothelial inflammation, hypotension and syncope, fatigue and abdominal pain. Encouraging signs of clinical activity included two bone marrow complete remissions in refractory anaemia with excess blasts type 1 patients previously treated with azacitidine. In addition, four patients each achieved transfusion independence and haematological improvements. In conclusion, oral rigosertib is bioavailable and well tolerated, and has clinical activity in patients with MDS.

Clinical activity and safety of the dual pathway inhibitor rigosertib for higher risk myelodysplastic syndromes following DNA methyltransferase inhibitor therapy.

Rigosertib (ON 01910.Na) is an inhibitor of the phosphoinositide 3‐kinase and polo‐like kinase pathways that induces mitotic arrest and apoptosis in neoplastic cells, while sparing normal cells. Our purpose is to summarize the clinical activity and safety of intravenous (IV) rigosertib delivered by an external ambulatory infusion pump in patients with refractory anemia with excess blasts‐1, ‐2, or, ‐t myelodysplastic syndromes (MDS) following prior treatment with DNA methyltransferase (DNMT) inhibitors. A total of 39 patients with MDS who fulfilled these criteria were enrolled in four phase 1‐2 clinical trials of IV rigosertib. Thirty five (88%) had higher risk disease according to the Revised International Prognostic Scoring System. Median overall survival for this group of 39 patients was 35 weeks. Of 30 evaluable patients with follow‐up bone marrow biopsies, 12 (40%) achieved complete (n = 5) or partial (n = 7) bone marrow blast responses. In addition, 15 patients achieved stabilization of bone marrow blasts. One patient with a complete bone marrow response also achieved a complete cytogenetic response. A second patient with stable bone marrow blasts achieved a partial cytogenetic response. Two of the responding patients and three patients with stable disease had hematological improvements. Rigosertib‐induced bone marrow blast decreases and stability appeared to be predictive of prolonged survival. IV rigosertib had a favorable safety profile without significant myelosuppression. Most common drug‐related toxicities included fatigue, diarrhea, nausea, dysuria, and hematuria. In summary, IV rigosertib is well tolerated and has clinical activity in patients with higher risk MDS following DNMT inhibitor treatment. A multinational pivotal phase 3 randomized clinical trial of rigosertib versus best supportive care for patients with MDS with excess blasts following prior treatment with DNMT inhibitors (ONTIME: ON 01910.Na Trial In Myelodysplastic SyndromE) has recently completed enrollment.

Phase I Study of Rigosertib, an Inhibitor of the Phosphatidylinositol 3-Kinase and Polo-like Kinase 1 Pathways, Combined with Gemcitabine in Patients with Solid Tumors and Pancreatic Cancer

Purpose: Rigosertib, a dual non-ATP inhibitor of polo-like kinase 1 (Plk1) and phosphoinositide 3-kinase pathways (PI3K), and gemcitabine have synergistic antitumor activity when combined in preclinical studies. This phase I study aimed to determine the recommended phase II dose (RPTD) of the combination of rigosertib and gemcitabine in patients with cancer. Experimental Design: Patients with solid tumors who failed standard therapy or were candidates for gemcitabine-based therapy were eligible. Gemcitabine was administered on days 1, 8, and 15 on a 28-day cycle and rigosertib on days 1, 4, 8, 11, 15, and 18. Pharmacokinetic studies were conducted during an expansion cohort of patients with advanced pancreatic ductal adenocarcinoma (PDA). Results: Forty patients were treated, 19 in the dose-escalation phase and 21 in the expansion cohort. Dose levels evaluated were (gemcitabine/rigosertib mg/m2): 750/600 (n = 4), 750/1,200 (n = 3), 1,000/600 (n = 3), 1,000/1,200 (n = 3), and 1,000/1,800 (n = 6 + 21). One dose-limiting toxicity (death) occurred at the highest dose level (1,000/1,800) tested. Non–dose-limiting ≥grade II/III toxicities included neutropenia, lymphopenia, thrombocytopenia, fatigue, and nausea. Grade III/IV neutropenia, thrombocytopenia, and fatigue were seen in two, one, and two patients in the expansion cohort. Partial responses were observed in PDA, thymic cancer, and Hodgkin lymphoma, including gemcitabine-pretreated PDA. The pharmacokinetic profile of rigosertib was not affected by gemcitabine. Conclusion: The RPTD established in this study is rigosertib 1,800 mg/m2 and gemcitabine 1,000 mg/m2. This regimen is well tolerated with a toxicity profile of the combination similar to the profile of gemcitabine alone. Antitumor efficacy was observed in patients who previously progressed on gemcitabine-based therapy. Clin Cancer Res; 18(7); 2048–55. ©2012 AACR.

Phase I study of oral rigosertib (ON 01910.Na), a dual inhibitor of the PI3K and Plk1 pathways, in adult patients with advanced solid malignancies.

Purpose: To determine the pharmacokinetics (PK), maximum tolerated dose (MTD), safety, and antitumor activity of an oral formulation of rigosertib, a dual phosphoinositide 3-kinase (PI3K) and polo-like kinase 1 (Plk1) pathway inhibitor, in patients with advanced solid malignancies. Experimental Design: Patients with advanced solid malignancies received rigosertib twice daily continuously in 21-day cycles. Doses were escalated until intolerable grade ≥2 toxicities, at which point the previous dose level was expanded to define the MTD. All patients were assessed for safety, PK, and response. Urinary PK were performed at the MTD. Archival tumors were assessed for potential molecular biomarkers with multiplex mutation testing. A subset of squamous cell carcinomas (SCC) underwent exome sequencing. Results: Forty-eight patients received a median of 2 cycles of therapy at 5 dose levels. Rigosertib exposure increased with escalating doses. Dose-limiting toxicities were hematuria and dysuria. The most common grade ≥2 drug-related toxicities involved urothelial irritation. The MTD is 560 mg twice daily. Activity was seen in head and neck SCCs (1 complete response, 1 partial response) and stable disease for ≥12 weeks was observed in 8 additional patients. Tumors experiencing ≥partial response had PI3K pathway activation, inactivated p53, and unique variants in ROBO3 and FAT1, two genes interacting with the Wnt/β-catenin pathway. Conclusions: The recommended phase II dose of oral rigosertib is 560 mg twice daily given continuously. Urinary toxicity is the dose-limiting and most common toxicity. Alterations in PI3K, p53, and Wnt/β-catenin pathway signaling should be investigated as potential biomarkers of response in future trials. Clin Cancer Res; 20(6); 1656–65. ©2014 AACR.

Phase I study of ON 01910.Na (Rigosertib), a multikinase PI3K inhibitor in relapsed/refractory B-cell malignancies

Phase I study of ON 01910.Na (Rigosertib), a multikinase PI3K inhibitor in relapsed/refractory B-cell malignancies

Initiation of epoetin-α therapy at a starting dose of 120,000 units once every 3 weeks in patients with cancer receiving chemotherapy

BACKGROUND Epoetin-alpha initiated once weekly, followed by once-every-3-weeks maintenance, was effective and well tolerated for chemotherapy-induced anemia. This study evaluated a starting dose of epoetin-alpha 120,000 U once every 3 weeks for chemotherapy-induced anemia using early and late initiation regimens. METHODS Patients with baseline hemoglobin 11.0-12.0 g/dL were randomly assigned to early intervention with immediate epoetin-alpha (n = 68) or to standard intervention with epoetin-alpha when hemoglobin decreased to <11 g/dL (n = 68). A third group of patients with baseline hemoglobin <11 g/dL (n = 50) were enrolled but not randomized; epoetin-alpha was initiated immediately. The primary endpoint was mean proportion of hemoglobin values within the target range (11.0-13.0 g/dL) among randomized patients. RESULTS The mean proportion of hemoglobin values in range through week 16 was 60% in each randomized group. Mean hemoglobin by week showed similar increases over the study. Blood transfusions were administered in 9%, 8%, and 24% of patients in the early, standard, and nonrandomized groups. Mean epoetin-alpha doses were similar between treatment groups. Dose reductions and withholds were more common in the early intervention group. Adverse events (eg, diarrhea, fatigue, nausea) were consistent with the safety profile for epoetin-alpha . Clinically relevant thrombotic vascular events (regardless of relationship to study treatment) were reported for 9%, 12%, and 12% of patients in the early, standard, and nonrandomized groups. CONCLUSIONS Early and standard intervention with epoetin-alpha, administered once every 3 weeks, increased and maintained hemoglobin levels within 11.0-13.0 g/dL in patients with chemotherapy-induced anemia.Epoetin‐α initiated once weekly, followed by once‐every‐3‐weeks maintenance, was effective and well tolerated for chemotherapy‐induced anemia. This study evaluated a starting dose of epoetin‐α 120,000U once every 3 weeks for chemotherapy‐induced anemia using early and late initiation regimens.

The Dual Pathway Inhibitor Rigosertib Is Effective in Direct Patient Tumor Xenografts of Head and Neck Squamous Cell Carcinomas

The dual pathway inhibitor rigosertib inhibits phosphoinositide 3-kinase (PI3K) pathway activation as well as polo-like kinase 1 (PLK1) activity across a broad spectrum of cancer cell lines. The importance of PIK3CA alterations in squamous cell carcinoma of the head and neck (HNSCC) has raised interest in exploring agents targeting PI3K, the product of PIK3CA. The genetic and molecular basis of rigosertib treatment response was investigated in a panel of 16 HNSCC cell lines, and direct patient tumor xenografts from eight patients with HNSCC [four HPV-serotype16 (HPV16)–positive]. HNSCC cell lines and xenografts were characterized by pathway enrichment gene expression analysis, exon sequencing, gene copy number, Western blotting, and immunohistochemistry (IHC). Rigosertib had potent antiproliferative effects on 11 of 16 HPV− HNSCC cell lines. Treatment sensitivity was confirmed in two cell lines using an orthotopic in vivo xenograft model. Growth reduction after rigosertib treatment was observed in three of eight HNSCC direct patient tumor lines. The responsive tumor lines carried a combination of a PI3KCA-activating event (amplification or mutation) and a p53-inactivating event (either HPV16- or mutation-mediated TP53 inactivation). In this study, we evaluated the in vitro and in vivo efficacy of rigosertib in both HPV+ and HPV− HNSCCs, focusing on inhibition of the PI3K pathway. Although consistent inhibition of the PI3K pathway was not evident in HNSCC, we identified a combination of PI3K/TP53 events necessary, but not sufficient, for rigosertib sensitivity. Mol Cancer Ther; 12(10); 1994–2005. ©2013 AACR.

Abstract CT236: Advanced solid cancer therapy with a novel antibody-drug conjugate (ADC), sacituzumab govitecan (IMMU-132): key preclinical and clinical results

Background: Sacituzumab govitecan (IMMU-132) is a new ADC comprising SN-38, the active metabolite of the topoisomerase inhibitor, camptothecin (irinotecan), conjugated to an anti-Trop-2 antibody. In vitro and in vivo preclinical data suggest that IMMU-132 is a unique ADC, being most efficacious at a high drug-antibody ratio (DAR) of 7.6, and capable of delivering up to 135-fold more SN-38 than its parental drug, irinotecan, in a human cancer xenograft. In vitro studies also demonstrate specific double-stranded DNA breaks by the internalizing ADC. Methods: IMMU-132 is completing a phase I/II clinical trial with phase II expansion after MTD determination (ClinicalTrials.gov.NCT01631552) in patients with advanced cancers that typically express high levels of Trop-2, at doses of 8 and 10 mg/kg on days 1 and 8 of 21-day repeated cycles. Efficacy (N = 91) and safety (N = 130) results are provided. Results: The% of grades 3/4 AEs for both dose levels are neutropenia (16/4), febrile neutropenia (4/4), anemia (4/0), diarrhea (4/0), and fatigue (4/0) (Table 1). No patient discontinued therapy due to toxicity, and no patient showed immunogenicity despite repeated therapy. Patient dose reductions were 15-16%, and dose delays after first 2 cycles were 3-4%. Conclusions: IMMU-132 shows activity in patients with diverse cancers, even when they no longer responded to a topoisomerase inhibitor. It appears to have a manageable toxicity profile, with promising efficacy at a high therapeutic index in patients with heavily-pretreated metastatic cancers, especially TNBC, SCLC, and NSCLC. Based on these results, this ADC carrying a moderately-toxic drug that is the active metabolite of a currently-used camptothecin analogue represents a novel cancer therapeutic that challenges the current dogma of requiring ultratoxic drugs conjugated at low DARs for ADC therapy. Citation Format: Alexander N. Starodub, Allyson J. Ocean, Aditya Bardia, Michael J. Guarino, Wells Messersmith, Jordan Berlin, Vincent J. Picozzi, Sajeve S. Thomas, Gregory Masters, Linda T. Vahdat, Ingrid A. Mayer, Rebecca Moroose, Jennifer S. Diamond, Scott T. Tagawa, Manish A. Shah, Francois Wilhelm, William A. Wegener, Pius Maliakal, Robert M. Sharkey, David M. Goldenberg. Advanced solid cancer therapy with a novel antibody-drug conjugate (ADC), sacituzumab govitecan (IMMU-132): key preclinical and clinical results. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT236. doi:10.1158/1538-7445.AM2015-CT236