FDA Approval Summary: Decitabine and Cedazuridine Tablets for Myelodysplastic Syndromes.

On July 7, 2020, the Food and Drug Administration approved Inqovi (Otsuka Pharmaceutical Co.), an oral fixed-dose combination tablet comprising 35 mg decitabine, a hypomethylating agent, and 100 mg cedazuridine, a cytidine deaminase inhibitor (abbreviated DEC-C) for treatment of adult patients with myelodysplastic syndromes (MDS). Evidence of effectiveness of DEC-C was established in phase III ASTX727-02 (N = 133) in adults with MDS. The study involved a two-sequence crossover comparing DEC-C and intravenous (IV) decitabine 20 mg/m2 once daily for the first 5 days of each 28-day cycle in the first 2 cycles. From cycle 3 onward, patients received DEC-C. Five-day cumulative area under the curve (5-d AUC) of decitabine for DEC-C was similar to that of IV decitabine, with geometric mean ratio 0.99 (90% confidence interval: 0.93-1.06). Clinical benefit was supported by study ASTX727-02 and the similarly designed phase II study ASTX727-01-B (n = 80), with complete remission (CR) of 21% and 18% and median duration of CR 7.5 and 8.7 months, respectively. Adverse reactions were consistent with IV decitabine. Postmarketing assessments were issued to address the effect of cedazuridine on QT prolongation, food effect, moderate and severe hepatic impairment, and severe renal impairment on the pharmacokinetics and safety of DEC-C.

FDA Approval Summary: Calaspargase Pegol-mknl For Treatment of Acute Lymphoblastic Leukemia in Children and Young Adults.

On December 20, 2018, the Food and Drug Administration approved calaspargase pegol-mknl (CALASP), an asparagine-specific enzyme, as a component of a multi-agent chemotherapeutic regimen for acute lymphoblastic leukemia (ALL) in pediatric and young adult patients age 1 month to 21 years. Efficacy was determined on the basis of achievement and maintenance of steady-state nadir serum asparaginase activity (NSAA) above 0.1 U/mL when using CALASP, 2,500 U/m2 intravenously, every 3 weeks. In a randomized comparison to pegaspargase (PEGASP) every 2 weeks, treatment with CALASP every 3 weeks had a similar safety profile and no substantial impairment in event-free survival. The pharmacokinetics of CALASP were studied when administered in combination with multiagent chemotherapy in 124 patients with B-cell ALL in Study AALL07P4 and Study DFCI 11-001. The results showed that 123 [99%, 95% confidence interval (CI), 96%-100%] of the 124 patients maintained NSAA >0.1 U/mL at weeks 6, 12, 18, 24, and 30 of post-induction phase. Maintaining adequate NSAA levels is critical to successful treatment of ALL. Herein, we describe the FDA review and approval of CALASP.See related commentary by Lew, p. 325.

An FDA analysis of clinical hold deficiencies affecting investigational new drug applications for oncology products.

A systematic analysis of new commercial investigational new drug applications (IND) submitted to the FDA's Office of Hematology and Oncology Products (OHOP) in the Center for Drug Evaluation and Research was conducted to quantify the most common reasons INDs for oncology indications go on clinical hold. In OHOP, less than 10% of INDs went on hold or were withdrawn within the 30-day safety review period. Of INDs that were placed on hold, deficiencies were mainly clinical, followed by concerns related to pharmaceutical quality and nonclinical development. INDs were also characterized based on phase of development, product type, sponsors' regulatory experience, and occurrence of a pre-IND meeting. INDs that were placed on hold were mostly for first-in-human trials or submitted by sponsors with limited regulatory experience. INDs that went on hold or were safe-to-proceed had pre-IND meetings with comparable rates but sponsors with substantial experience appeared to benefit more from pre-IND meetings compared to those with limited experience. The time interval between the pre-IND meeting and the IND submission was longer for INDs that went on hold. To obtain useful FDA feedback on product development, it is essential to provide focused questions and supporting information in pre-IND meeting packages.

FDA Approval Summary: (Daunorubicin and Cytarabine) Liposome for Injection for the Treatment of Adults with High-Risk Acute Myeloid Leukemia.

On August 3, 2017, the FDA granted regular approval to Vyxeos (also known as CPX-351; Jazz Pharmaceuticals), a liposomal formulation of daunorubicin and cytarabine in a fixed combination, for the treatment of adults with newly diagnosed therapy-related acute myeloid leukemia (t-AML) or acute myeloid leukemia (AML) with myelodysplasia-related changes (AML-MRC). Approval was based on data from Study CLTR0310-301, a randomized, multicenter, open-label, active-controlled trial comparing Vyxeos with a standard combination of daunorubicin and cytarabine ("7+3") in 309 patients 60-75 years of age with newly diagnosed t-AML or AML-MRC. Because of elemental copper concerns with the Vyxeos formulation, patients with Wilson disease were excluded from the study. Vyxeos demonstrated an improvement in overall survival (HR 0.69; 95% confidence interval, 0.52-0.90; P = 0.005) with an estimated median overall survival of 9.6 months compared with 5.9 months for the "7+3" control arm. The toxicity profile of Vyxeos was similar to that seen with standard "7+3" with the exception of more prolonged neutropenia and thrombocytopenia on the Vyxeos arm. Because the pharmacology of Vyxeos differs from that of other formulations of daunorubicin and cytarabine, labeling includes a warning against interchanging formulations during treatment. This is the first FDA-approved treatment specifically for patients with t-AML or AML-MRC.

Bortezomib reduces pre-existing antibodies to recombinant immunotoxins in mice.

Recombinant immunotoxin (RIT) therapy is limited in patients by neutralizing Ab responses. Ninety percent of patients with normal immune systems make neutralizing Abs after one cycle of RIT, preventing repeated dosing. Furthermore, some patients have pre-existing Abs from environmental exposure to Pseudomonas exotoxin, the component of the RIT that elicits the neutralizing Ab response. Bortezomib is an U.S. Food and Drug Administration-approved proteasome inhibitor that selectively targets and kills plasma cells that are necessary for the neutralizing Ab response. We hypothesized that bortezomib may abrogate neutralizing Ab levels, making dosing of RIT possible in mice already immune to RIT. We immunized BALB/c mice with multiple doses of SS1P, a RIT whose Ab portion targets mesothelin. Mice with elevated Ab levels were separated into groups to receive saline, bortezomib, the pentostatin/cyclophosphamide (PC) regimen, or the bortezomib/PC (BPC) combination regimen. Four weeks after finishing therapy, plasma Ab levels were assayed, and bone marrow was harvested. The bortezomib and PC regimens significantly reduced Ab levels, and we observed fewer plasma cells in the bone marrow of bortezomib-treated mice but not in PC-treated mice. The BPC combination regimen almost completely eliminated Abs and further reduced plasma cells in the bone marrow. This regimen is more effective than individual regimens and may reduce Ab levels in patients with pre-existing neutralizing Abs to Pseudomonas exotoxin, allowing RIT treatment.

Proteolysis of complement factors iC3b and C5 by the serine protease prostate-specific antigen in prostatic fluid and seminal plasma.

Prostate-specific Ag (PSA) is a serine protease that is expressed exclusively by normal and malignant prostate epithelial cells. The continued high-level expression of PSA by the majority of men with both high- and low-grade prostate cancer throughout the course of disease progression, even in the androgen-ablated state, suggests that PSA has a role in the pathogenesis of disease. Current experimental and clinical evidence suggests that chronic inflammation, regardless of the cause, may predispose men to prostate cancer. The responsibility of the immune system in immune surveillance and eventually tumor progression is well appreciated but not completely understood. In this study, we used a mass spectrometry-based evaluation of prostatic fluid obtained from diseased prostates after removal by radical prostatectomy to identify potential immunoregulatory proteins. This analysis revealed the presence of Igs and the complement system proteins C3, factor B, and clusterin. Verification of these findings by Western blot confirmed the high-level expression of C3 in the prostatic fluid and the presence of a previously uncharacterized C-terminal C3 cleavage product. Biochemical analysis of this C3 cleavage fragment revealed a putative PSA cleavage site after tyrosine-1348. Purified PSA was able to cleave iC3b and the related complement protein C5. These results suggest a previously uncharacterized function of PSA as an immunoregulatory protease that could help to create an environment hospitable to malignancy through proteolysis of the complement system.

Trypsin-like proteolytic contamination of commercially available psa purified from human seminal fluid.

BACKGROUND: Prostate-Specific Antigen (PSA) is a serine protease whose expression is maintained in all stages of prostate cancer. A role for PSA in the pathobiology for prostate cancer has not been firmly established. Experimental studies to date support a role for PSA through mechanisms such as release or processing of growth factors and degradation of the extracellular matrix. Exposure of prostate cancer cells to exogenous PSA also results in gene expression changes. These in vitro and biochemical assays rely on the use of commercially available PSA. Contamination of these commercial preparations can significantly impact the results of these in vitro studies. METHODS: We characterized PSA and trypsin-like activity of PSA preparations obtained from three commercial sources: Calbiochem, Fitzgerald, and AbD Serotec. Silver stained gels were used to compare the purity of each preparation and mass spectrometry was performed to characterize contaminating proteases. RESULTS: PSA activity varied between PSA preparations with AbD Serotec PSA having highest degree of activity. Significant trypsin-like activity, which was inhibited by aprotinin, was observed in PSA preparations from Calbiochem and Fitzgerald, but not AbD Serotec. These former two PSA preparations also contained the greatest degree of non-PSA contaminants by silver stain and mass spectrometry. CONCLUSIONS: Commercially available preparations of PSA contain contaminating proteins, including trypsin-like protease activity, that could potentially complicate the interpretation of results obtained from in vitro studies assessing PSA proteolysis of potential protein substrates and effects of PSA on gene expression.

Activated stress response pathways within multicellular aggregates utilize an autocrine component.

Multicellular aggregates (spheroids) of primary human foreskin fibroblasts (HFF-2) and a glioblastoma cell line (T98G) entered and exited from long term (2 weeks) metabolic arrest utilizing an autocrine response. Cytokine production (specifically IFN-gamma) activated a Gadd45alpha/p38 pathway that led to increased AP-1 (c-jun and ATF3) transcription factor levels, augmenting cytokine production in an autocrine fashion. Whereas HFF-2 aggregates were capable of surviving long term arrest and recovery during NF-kappaB inhibition independent of JNK activation, T98G aggregates were not. Such endogenous processes are not easily observed with adherent monolayer cell culturing systems, strongly suggesting that more emphasis needs to be placed on determining the operational signal transduction cascades within multicellular aggregates. Extracellular inputs such as spheroid formation, arrest, and regrowth as monolayers invoke intracellular signaling responses converging at the AP-1 transcription factor level. Variations in responses are both cell type and transformation state dependent and require an autocrine cytokine component. The data are discussed in relation to the wounding response and avascular tumor growth mechanisms.