Phase-1 study of isophosphoramide mustard (IPM)-lysine in advanced cancers

9524

Background: IPM is a bi-functional alkylator which cross-links DNA through G:C base-pairs resulting in irreparable 7-atom inter-strand cross-links. IPM is the active moiety of ifosfamide (IFOS), a pro-drug of IPM. IPM is active in diverse cancer models but is unstable. We stabilized IPM with lysine (IPM-lysine; ZIO-201). ZIO-201 was active in pre-clinical models including human cancer cell lines, human-mouse xenografts and cancers resistant to cyclophosphamide (CPA) and IFOS. Because ZIO-201 is not metabolized to acrolein or chloroacetaldehyde, bladder and CNS toxicities are unlikely. Methods: Phase-1 trial in subjects with advanced cancers. ZIO-201 was given daily for 3 consecutive d at a starting dose of 30 mg/me2/d every 3 w. Neither mesna nor IV hydration were given. 11 dose levels were studied in 18 subjects up to 795 mg/me2/d; dose-escalation continues. Data on the 1st 15 subjects are available for analysis. Results: Median age was 59 y (range, 18–70 y); 10 subjects were male. Diagnoses included colorectal cancer (N=5), sarcoma (N=3) and 1 subject each with gastric, lung, bladder, prostate, ovary and thyroid cancers and mesothelioma. 7 had extensive and 8, limited disease. All subjects received extensive prior therapy. Median N cycles was 2 (range, 1–13). Toxicities ≥ grade-2 occurring in > 20% of subjects included anemia (N subjects=4) and diverse GI complaints (N=4). 4 of 8 subjects receiving doses > 445 mg/me2/d had transient proximal renal tubular acidosis. There was no hemorrhagic cystitis or CNS toxicity. 1 subject with mesothelioma had stable disease > 13 mo. Pharmacokinetic studies at 595 mg/me2/d showed a tmax = 13 min (SD ± 9 min), Cmax = 44.7 μg/mL (SD ± 34.1 μg/mL), t1/2 = 35 min (SD ± 7 min) and AUC0-∞ = 1.68 mg·min/ml (SD ± 1.26 mg·min/ml). Conclusions: These data suggest a possible role for ZIO-201 in IFOS-sensitive cancers (especially sarcoma and lymphoma). ZIO-201 may also be active in CPA and IFOS-resistant cancers. Comparable or greater efficacy with less toxicity is expected.

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Phase I experience with an anti-glycotope monoclonal antibody, RAV12, in recurrent adenocarcinoma

13002

Background: RAV12 is a high affinity, internalizing, chimeric IgG1 monoclonal antibody (MAb) that binds RAAG12, a novel primate-restricted N-linked carbohydrate epitope present on multiple cell-surface proteins. RAAG12 is variably expressed on normal non-keratinizing epithelia and is not expressed on human tissues from the cardiovascular, endocrine, hematolymphatic, neuromuscular, and central nervous systems. The majority of RAAG12 expression is in the cytoplasm. In some cases, e.g. polarized epithelia such as colon and stomach, RAAG12 is located in both the cytoplasm and the apical membrane. IHC studies demonstrated that > 90% of human colon, gastric, and pancreatic adenocarcinoma samples bound RAV12, indicating expression of RAAG12. RAAG12 is distinct from previously reported mucin or Lewis blood group carcinoma-associated carbohydrates. Methods: In December 2004, a phase I dose-escalation safety and pharmacokinetics (PK) trial was begun in patients with recurrent (1 to 3 prior treatments) adenocarcinoma. RAV12 was administered weekly × 4. Fourteen patients have received treatment, 6 in a first cohort at 0.3 mg/kg, and 8 in a second cohort at 1.0 mg/kg. Nine patients had colorectal, 2 gastroesophageal, 2 pancreatic, and 1 lung cancer. Responses were evaluated on day 42. Results: All patients, except one who experienced an HSR during his fourth dose, completed the planned weekly treatments. Three clinical syndromes have been observed to date: 1) abdominal cramping pain and diarrhea (11 patients) particularly at the higher dose, 2) asymptomatic, self-limited, rapidly reversible excursions of liver function tests (3 patients), and 3) asymptomatic, self-limited, rapidly reversible excursions of pancreatic enzymes (2 patients). Three patients had stable disease as a best response at day 43. One patient, with pancreatic cancer, had a > 50% reduction in CA19–9, continued treatment for a total of 9 doses, and had a period of disease stability of 5 months. Preliminary analysis demonstrated dose-dependent PK. Dose escalation continues at 1.5 mg/kg. Conclusions: RAV12 may have activity in recurrent adenocarcinoma. Side-effects, though present, have been manageable. Further experience with the MAb will be required to evaluate safety and activity.

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Safety and antitumor activity of AMG 706 in patients (pts) with thyroid cancer (TC): A subset analysis from a phase 1 dose-finding study

3030

Background: AMG 706 is an investigational, oral, small molecule multi-kinase inhibitor with both antiangiogenic and direct antitumor activity that selectively targets VEGF, PDGF, and Kit receptors. From a phase 1 study (Rosen ASCO 2005; Herbst EORTC 2005), encouraging antitumor activity was seen in pts with TC. In this analysis, we report on the TC subset from the study. Methods: Pts with refractory solid tumors received oral AMG 706 QD (50, 100, 125, 175 mg) or BID (25 mg) intermittently or continuously for 28-day cycles. Study objectives were to assess safety, establish the maximum tolerated dose (MTD), and generate pharmacokinetic profiles of AMG 706 in these pts. Tumor response (modified RECIST) was evaluated at wk 8 and Q12W thereafter. Data from Oct 2005 were analyzed. Results: In this study, 7 of 71 pts enrolled had TC. Baseline demographics for this subset were 4 W/3 M, median (range) age of 58 (41, 78) yrs, ECOG 1 (71%), and all had stage IV disease. Histologies were papillary (3: PTC), follicular (1; FTC), Hürthle cell (1), anaplastic (1), and medullary TC (1; MTC). All pts received prior external radiotherapy, radioiodine, chemotherapy, and/or surgery. Initial doses of AMG 706 were 125 mg and 175 QD and 25 mg BID. The MTD for the study was 125 mg QD. Median (range) time on treatment for the TC pts was 141 (14, 564) days. Treatment-related adverse events are summarized ( table ). Best objective responses were 3 pts with partial response (PR), 3 with stable disease (SD), and 1 with progressive disease. PR was seen in pts with MTC, PTC and FTC. Two pts with PR did not have confirmation of response (1 had a PR during the last assessment). The 3 pts with PR received AMG 706 for 338, 366, and 564 days; 2 pts are still receiving AMG 706. Time to response for these 3 pts were 210, 217, and 304 days. Conclusion: In patients with TC, AMG 706 appears to be relatively well tolerated and displays promising antitumor activity for some pts. Based on these favorable findings, a phase 2 study of AMG 706 for the treatment of advanced TC is ongoing.

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Lipid kinases are novel effectors of the GTPase Rac1

We have found that a complex consisting of a type I PIPK and a DGK associates with the GTPase Rac1. Binding of the lipid kinase complex is through the C-terminus of Rac. Complex formation is augmented in the presence of specific phospholipids. The complex also associates with Rho GDI, through Rac. Based on the role of PtdIns-4,5-P2 in regulating proteins that influence actin structures we propose that the Rac-associated lipid kinase complex functions to generate locally high concentrations of PtdIns-4,5-P2 in a Rac-dependent manner. There are many possible roles PtdIns-4,5-P2 might play. A likely role is binding to barbed-end actin capping proteins. This would release the capping protein, providing free barbed ends for actin polymerization. Uncapping would occur at the membrane so that additional actin polymerization would result in membrane protrusions and lamellapodia, in a Brownian ratchet model. It is also possible that PtdIns-4,5-P2 has other roles, such as promoting the release of G actin from profilin or promoting the cross-linking of actin or its anchorage to the plasma membrane. Studies are currently underway to determine the role of this lipid kinase complex in Rac signaling and actin regulation in vivo.

Alteration in the frequency, severity and duration of chemotherapy-induced mucositis in hamsters by interleukin-11

Ninety-five young, male Golden Syrian hamsters were randomly divided into five equally sized groups. One group served as a placebo control while the animals in the others received one of four doses of interleukin-eleven (IL-11) twice daily given by subcutaneous injection beginning on the first day of chemotherapy (day 0) and continuing to day 14. Mucositis was induced with 5-fluorouracil using a standard regimen of 60 mg/kg, intraperitoneally on days 0 and 2 followed by superficial mucosal irritation on day 4. Animals were evaluated daily beginning on day 6. Mucositis was assessed using a standardised technique in which randomly numbered daily mucosal photographs were scored by three blinded independent observers at the conclusion of the experiment. IL-11 favourably affected the frequency, severity and duration of mucositis. This phenomenon appeared to be dose dependent. Hamsters receiving 30 and 100 micrograms per day of IL-11 demonstrated significantly (P < 0.05) lower mucositis scores than did either the control or animals receiving 3 or 10 micrograms per day, although the latter had marginal beneficial effects. Additionally, survival was significantly better for hamsters receiving higher doses of IL-11 (85%) compared to the placebo control (46%). IL-11 administration also favourably affected weight loss. While stimulation of platelet production was noted in animals receiving IL-11, a lack of difference in bone marrow cellularity between test and control animals suggests that the mechanism by which IL-11 modifies mucositis is mediated at the epithelial or connective tissue level rather than through the marrow. The kinetics of IL-11 alteration of mucositis induction supports such a hypothesis. Further investigation is currently underway to establish a definitive mechanism by which IL-11 protects the oral mucosa.

Prevention of chemotherapy-induced ulcerative mucositis by transforming growth factor beta 3

Mucositis is a common, dose-limiting complication in patients receiving cancer chemotherapy, which appears to be a consequence of the rate of epithelial proliferation. The beta transforming growth factors have been shown to be negative regulators of epithelial cell proliferation. Here we show that transforming growth factor beta 3 administration reduced proliferation of oral epithelium in vitro and in vivo. Topical application of transforming growth factor beta 3 to the oral mucosa of the Syrian golden hamster prior to chemotherapy significantly reduced the incidence, severity, and duration of oral mucositis, reduced chemotherapy-associated weight loss, and increased survival.