Abstract Background: Sotatercept is a recombinant activin receptor IIA (ActRIIA) ligand trap and is comprised of the extracellular domain of ActRIIA linked to the Fc domain of human IgG1 (ActRIIA-IgG1). Results of preclinical and early clinical studies provide evidence that sotatercept increases the concentration of hemoglobin (Hb) in blood and may constitute a novel treatment for chemotherapy-induced anemia (CIA), a condition that results in significant morbidity. Methods: This study evaluated the safety of, and hematopoietic response to, sotatercept in patients with CIA and metastatic breast cancer (MBC). Response was defined as increase in Hb ≥1 g/dL for ≥28 consecutive days during treatment or ≤2 months following the last dose, in the absence of red blood cell (RBC) transfusion or treatment with an erythropoiesis stimulating agent (ESA). If RBC transfusion or treatment with an ESA was required, no Hb measurements within 28 days of the RBC transfusion or administration of ESA were used to determine the Hb response. Subjects were randomized to subcutaneous injection of sotatercept (0.1, 0.3, or 0.5 mg/kg) or placebo and were treated on day 1 of each of four 28-day cycles. Results: Thirty (30) subjects were enrolled and treated (5 placebo, 25 sotatercept). Increases in mean Hb in the 0.3 and 0.5 mg/kg groups were greater than in 0.1 mg/kg and placebo groups. Increases peaked approximately 15 days following treatment and declined over the remaining interval between treatments. Among 23 subjects with confirmed CIA and administered ≥1 dose and followed for ≥57 days (per-protocol analysis), 5/18 (28%) administered sotatercept responded (0/5 [0%] at 0.1 mg/kg; 3/9 [33%] at 0.3 mg/kg; 2/4 [50%] at 0.5 mg/kg) vs 1/5 [20%] administered placebo. Among 13 nonresponders administered sotatercept, 5 (39%) experienced ≥1 dose interruption/reduction, as per protocol, due to elevated Hb. The incidence of adverse events (AEs) was consistent with that reported in patients with MBC. No dose-limiting or dose-related toxicity was observed. Conclusions: Sotatercept demonstrated dose-dependent hematopoietic activity in subjects with CIA and MBC. The safety findings were generally consistent with the known safety profile of sotatercept. These data suggest that a greater dose of sotatercept or a dose interval <28 days might result in a more sustained, and greater rate of, hematopoietic response. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-20-03.

Abstract Background: Only half of HER2-positive metastatic breast cancer patients will respond to first-line trastuzumab-containing therapy, but of these, most will progress within a year. Trastuzumab resistance remains a continuing clinical problem, and better biomarkers and therapies are needed. Activin A is a TGF-beta superfamily member that regulates cell proliferation, apoptosis, differentiation, and immune response. We have previously reported that higher pretreatment serum activin A level predicted reduced progression-free survival (PFS) and overall survival (OS) to first-line trastuzumab, independent of age, line of therapy, CA 15–3, and hormone receptor status (ASCO Ab ID 607, 2012). Methods: Serum activin A was measured using ELISA (R&D Systems, Minneapolis, MN) in 60 metastatic breast cancer patients before and 1 month after starting first-line trastuzumab-containing therapy. PFS and OS were analyzed using the Kaplan-Meier method and Cox modeling with both continuous and dichotomous (median) serum activin A analyses. Results: Pretreatment serum activin A levels had a median of 629 pg/mL and an inter-quartile range of 406 to 1791 pg/mL. There was no significant change in activin A levels between pretreatment and one month after starting trastuzumab therapy. Median activin A level at one month was 655 pg/mL, with an inter-quartile range of 405 to 1517 pg/mL. 83% of patients who had low pretreatment activin A levels (below median) had low activin levels at one month, and 83% who had high activin levels (above median) at baseline had high activin A levels at one month. Patients who had high activin A levels at baseline and one month had the worst outcome for both PFS (HR 3.9; median 134 days vs.776 days; p < 0.0001) and OS (HR 6.7; p < 0.0001) when compared to patients with low activin A levels which remained low at one month. Conclusions: Higher pretreatment and 1 month post-treatment serum activin A predicted for reduced PFS and overall survival in metastatic breast cancer patients treated with first-line trastuzumab-containing therapy. Trastuzumab-based therapy did not have a significant effect on activin A levels at one month. Patients with persistently high activin A levels had significantly worsened outcomes compared to those with low activin A levels. Serum activin A deserves further study to select patients most likely to respond to activin A-targeted therapy. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-06-33.

This open-label, dose-escalation study evaluated the safety and efficacy of single-agent gemtuzumab ozogamicin, a humanized anti-CD33 antibody-targeted chemotherapeutic agent, for pediatric patients with multiple relapsed or primary refractory acute myeloid leukemia (AML). Twenty-nine children 1 to 16 years of age (relapsed disease, 19; refractory disease, 10) received gemtuzumab ozogamicin ranging from 6 to 9 mg/m(2) per dose for 2 doses (separated by 2 weeks) infused over 2 hours. All patients had anticipated myelosuppression. Other toxicities included grade 3/4 hyperbilirubinemia (7%) and elevated hepatic transaminase levels (21%); the incidence of grade 3/4 mucositis (3%) or sepsis (24%) was relatively low. One patient treated at 9 mg/m(2) developed veno-occlusive disease (VOD) of the liver and defined the dose-limiting toxicity. Thirteen patients underwent hematopoietic stem-cell transplantation less than 3.5 months after the last dose of gemtuzumab ozogamicin; 6 (40%) developed VOD. Eight of 29 (28%) patients achieved overall remission. Remissions were comparable in patients with refractory (30%) and relapsed (26%) disease. Mean multidrug resistance-protein-mediated drug efflux was significantly lower in the leukemic blasts of patients achieving remission (P < .005). Gemtuzumab ozogamicin was relatively well tolerated at 6 mg/m(2) for 2 doses and was equally effective in patients with refractory and relapsed disease. Further studies in combination with standard induction therapy for childhood AML are warranted.

BACKGROUND. In this study, the authors analyzed the efficacy and safety of gemtuzumab ozogamicin (GO) (Mylotarg (R)), an antibody-targeted chemotherapy for CD33-positive acute myeloid leukemia (AML).METHODS. Patients with CD33-positive AML in first recurrence were entered in 3 open-label, single-arm, Phase II studies. Patients received monotherapy with GO 9 mg/m(2) as a 2-hour intravenous infusion in 2 doses separated by 2 weeks. Patients were evaluated for remission, survival, and treatment-emergent adverse events.RESULTS. Two hundred seventy-seven patients (median age, 61 yrs) were treated with GO, and 71 patients (26%) achieved remission, which was defined as : 5% blasts in the bone marrow without leukemic blasts in the peripheral blood, neutrophil recovery to 1500/mu L, hemoglobin >= 9 g/dL, and independence from red blood cell and platelet transfusions. Complete remission (CR) with platelet recovery (>= 100,000/mu L) or without full platelet recovery (< 100,000/mu L) (CRp) was observed in 35 patients (13%) and 36 patients (13%), respectively. The median recurrence-free survival was 6.4 months for patients who achieved CR and 4.5 months for patients who achieved CRp. Although expected incidences of Grade 3 or 4 neutropenia (98%) and thrombocytopenia (99%) were observed, the incidence of Grade 3 or 4 sepsis (17%) and pneumonia (8%) was relatively low. Grade 3 or 4 hyperbilirubinemia and hepatic aspartate aminotransferase and alanine aminotransferase elevations were reported in 29%, 18%, and 9% of patients, respectively; 0.9% of patients who did not undergo prior or subsequent hematopoietic stem cell transplantation developed hepatic venoocclusive disease after GO treatment.CONCLUSIONS. When it was administered to patients with CD33-positive AML in first recurrence, single-agent GO induced a 26% remission rate with a generally acceptable safety profile.

Progression of cutaneous T-cell lymphoma (CTCL) is associated with profound defects in cell-mediated immunity and depressed production of cytokines, which support cell-mediated immunity. Because we have observed marked defects in interleukin-12 (IL-12) production in CTCL and because IL-12 is critical for antitumor cytotoxic T-cell responses, we initiated a phase I dose escalation trial with recombinant human IL-12 (rhIL-12) where patients received either 50, 100, or 300 ng/kg rhIL-12 twice weekly subcutaneously or intralesionally for up to 24 weeks. Ten patients were entered: 5 with extensive plaque, 3 with Sezary syndrome, and 2 with extensive tumors with large cell transformation. One patient with Sezary syndrome dropped out after 1 week for personal reasons. Subcutaneous dosing resulted in complete responses (CR) in 2 of 5 plaque and partial responses (PR) in 2 of 5 plaque, and 1 of 2 Sezary syndrome (overall response rate CR+PR 5 of 9, 56%). A minor response also occurred in 1 of 5 plaque patients. Intralesional dosing resulted in individual tumor regression in 2 of 2 patients. Biopsy of regressing lesions showed a significant decrease in the density of the infiltrate in all cases and complete resolution of the infiltrate among those with clinical lesion resolution. An increase in numbers of CD8-positive and/or TIA-1-positive T cells were observed on immunohistochemical analysis of skin biopsy specimens obtained from regressing skin lesions. Adverse effects of rhIL-12 on this regimen were minor and limited and included low-grade fever and headache. One patient discontinued rhIL-12 at week 6 because of depression. These results suggest that rhIL-12 may augment antitumor cytotoxic T-cell responses and may represent a potent and well-tolerated therapeutic agent for CTCL.

Interleukin-12 (IL-12) is a key regulator of cell-mediated immunity that has therapeutic potential in cancer and infectious disease. In a previous Phase 1 dose escalation study of a single test dose of recombinant human IL-12 (rhIL-12) followed 14 days later by cycles of five consecutive daily intravenous injections every 3 weeks, we showed that a dose level up to 500 ng/kg could be administered with acceptable levels of safety. Based on these results, a Phase 2 study was conducted. In the Phase 2 study, however, administration of rhIL-12 at this same dose level resulted in severe toxicities with some patients unable to tolerate more than two successive doses. Of the 17 patients receiving rhIL-12 in the Phase 2 study, 12 patients were hospitalized and two patients died. A thorough scientific investigation to determine the cause of this unexpected toxicity failed to identify any difference in the drug products used or the patient populations enrolled in the Phase 1 and Phase 2 studies that could have accounted for the profound difference in toxicity. The focus of the investigation therefore shifted to the schedule of rhIL-12 administration. We determined that a single injection of rhIL-12 2 weeks before consecutive dosing included in the Phase 1 study, but not in the schedule of administration in the Phase 2 study, has a profound abrogating effect on IL-12-induced interferon-gamma (IFN-gamma) production and toxicity. This observation of schedule-dependent toxicity of IL-12 has been verified in mice, as well as nonhuman primates. In this regard, a single injection of IL-12 before consecutive daily dosing protected mice and cynomolgus monkeys from acute toxicity including mortality and was associated with an attenuated IFN-gamma response. Because of this unique biologic response, careful attention to the schedule of administration is required to assure safe and effective clinical development of this highly promising cytokine.

Structural modifications of folic acid have generated various derivatives that act at different target sites. Well-known examples include the dihydrofolate reductase (DHFR) inhibitor methotrexate (MTX),1–3 the thymidylate synthase inhibitor 2-desamino-2-methyl-N10-propargyl-5,8-dideazafolic acid,4,5 and the glycinamide ribonucleotide formyltransferase inhibitor 5,10-dideaza-5,6,7,8-tetrahydrofolic acid.6,7 More recently, folate analogues containing ornithine in place of glutamate have been synthesized as inhibitors of folylpolyglutamate synthetase.8,9 These ornithine-containing analogues showed weaker activity than the corresponding glutamate-containing analogues on cell growth presumably because of inefficient transport across the cell membrane.9,10 In contrast, a novel derivative of an ornithine-containing antifolate, Nα-(4-amino-4-deoxypteroyl)-Nδ-hemiphthaloyl-Lornithine (PT523), exhibits potent in vitro and in vivo antitumor activity.11

Previous work has demonstrated that the cellular response to ionizing radiation includes transcriptional activation of the c-jun gene. The signaling events responsible for this response, however, remain unclear. The present studies have examined the effects of ionizing radiation on c-jun expression in a variant of HL-60 cells, designated HL-525, which is deficient in protein kinase C (PKC)-mediated signal transduction. The results demonstrate that these cells express low levels of PKC alpha and PKC beta transcripts and exhibit an attenuated induction of c-jun expression following treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA). In contrast, HL-525 cells respond to ionizing radiation with an increase in c-jun mRNA which is more pronounced than that in wild-type HL-60 cells. These cells similarly respond to ionizing radiation with increased expression of the jun-B, jun-D, c-fos, and fos-B genes. Nuclear run-on assays demonstrate that X-ray-induced c-jun expression in HL-525 cells is regulated by increases in the rate of c-jun gene transcription. Moreover, mRNA stability studies in irradiated HL-525 cells demonstrate that the half-life of c-jun transcripts is prolonged compared to that in wild-type cells. Studies with N-acetyl-L-cysteine (NAC), an antioxidant, suggest that X-ray-induced transcriptional activation of the c-jun gene is mediated at least in part through the formation of reactive oxygen intermediates (ROIs). In this context, H2O2 also induced c-jun expression in HL-525 cells, and this effect was inhibited by NAC.(ABSTRACT TRUNCATED AT 250 WORDS)