isotretinoin and Leukemia--Myeloid--Acute

In vitro studies that showed RA could cause growth arrest and differentiation of myelogenous leukemia and neuroblastoma led to clinical trials of retinoids in APL and neuroblastoma that increased survival for both of those diseases. In the case of APL, ATRA has been the drug of choice, and preclinical and clinical data support direct combinations of ATRA with cytotoxic chemotherapy. For neuroblastoma, a phase I study defined a dose of 13-cis-RA, which was tolerable in patients after myeloablative therapy, and a phase III trial that showed postconsolidation therapy with 13-cis-RA improved EFS for patients with high-risk neuroblastoma. Preclinical studies in neuroblastoma indicate that ATRA or 13-cis-RA can antagonize cytotoxic chemotherapy and radiation, so use of 13-cis-RA in neuroblastoma is limited to maintenance after completion of cytotoxic chemotherapy and radiation. A limitation on the antitumor benefit of ATRA in APL is the marked decrease in drug levels that occurs during therapy as a result of induction of drug metabolism, resulting in a shorter drug half-life and decreased plasma levels. Although early studies sought to overcome the pharmacologic limitations of ATRA therapy in APL, the demonstration that ATO is active against APL in RA-refractory patients has led to a focus on studies employing ATO. Use of 13-cis-RA in neuroblastoma has avoided the decreased plasma levels seen with ATRA. It is likely that recurrent disease seen during or after 13-cis-RA therapy in neuroblastoma is due to tumor cell resistance to retinoid-mediated differentiation induction. Studies in neuroblastoma cell lines resistant to 13-cis-RA and ATRA have shown that they can be sensitive, and in some cases collaterally hypersensitive, to the cytotoxic retinoid fenretinide. Fenretinide induces tumor cell cytotoxicity rather than differentiation, acts independently from RA receptors, and in initial phase I trials has been well tolerated. Clinical trials of fenretinide, alone and in combination with ceramide modulators, are in development.

Topics: Antineoplastic Agents; Child; Clinical Trials as Topic; Fenretinide; Humans; Isotretinoin; Leukemia, Myeloid, Acute; Neoplasms; Neuroblastoma; Randomized Controlled Trials as Topic; Receptors, Retinoic Acid; Retinoids; Tretinoin

In the present study, the effects of 9-cis retinoic acid (RA) and 13-cis RA on acute myeloblastic leukaemia (AML) cell growth and the induction of apoptosis as well as its relationship with bcl-2 and p53 were compared with those of all-trans RA (ATRA). The study was performed with the subclones of the retinoid-sensitive OCI/AML-2 cell line. The most prominent inhibitory effect on clonogenic cell growth and morphological apoptosis was shown by 9-cis RA. In addition, Western blotting revealed the most obvious translocation of p53 from cytosol to nucleus in the case of 9-cis RA, which was the only retinoid able to change the conformation of p53 from mutational to wild type, as demonstrated by flow cytometry. There was no difference between the retinoids in the downregulation of bcl-2 as analysed by Western blotting and flow cytometry. The RA receptor (RAR)-alpha antagonist had no effect on apoptosis in any of the three retinoids studied using the annexin V method. In conclusion, this study shows that 9-cis RA was a more potent agent than ATRA or 13-cis RA in inducing growth arrest and apoptosis in the OCI/AML-2 subclones. The effect was associated with the downregulation of bcl-2 and was hardly mediated through the RAR-alpha receptor, but might be related to the activation of p53.

Topics: Alitretinoin; Antineoplastic Agents; Apoptosis; Blotting, Western; Cell Count; Cell Division; Dose-Response Relationship, Drug; Flow Cytometry; Fluorescence; Humans; Isotretinoin; Leukemia, Myeloid, Acute; Proto-Oncogene Proteins c-bcl-2; Receptors, Retinoic Acid; Tretinoin; Tumor Cells, Cultured; Tumor Suppressor Protein p53

Isotretinoin (Roaccutane) was used in a patient with low differentiated cell leukemia. Poor general condition, very low blood cell count as well patient's lack of consent made chemotherapy impossible. The effect of isotretinoin treatment was full hematological and clinical remission. The general patient's condition did not require additional medication.

Topics: Aged; Humans; Isotretinoin; Leukemia, Myeloid, Acute; Male; Remission Induction

Forty-one patients with refractory acute non-lymphocytic leukemia (ANLL) in relapse were treated with 13-cis-retinoic acid (cRA) as salvage therapy. The cRA was given as a single oral dose of 100 mg/m2/day for 4 weeks. One patient achieved a complete remission and two patients achieved a partial remission with reduction of the bone marrow blast count from 40 to 20% after the first course. We recommend further study of cRA in combination with other agents in the treatment of ANLL in children.

Topics: Adolescent; Cell Division; Child; Child, Preschool; Drug Evaluation; Female; Humans; Infant; Isotretinoin; Leukemia, Megakaryoblastic, Acute; Leukemia, Monocytic, Acute; Leukemia, Myeloid, Acute; Leukemia, Myelomonocytic, Acute; Leukemia, Promyelocytic, Acute; Male; Remission Induction; Tumor Cells, Cultured

The addition of retinoic acid to human promyelocytic leukemia cells in culture results in their differentiation to mature myeloid forms with acquisition of the differentiated phenotype, i.e., the ability to reduce nitroblue tetrazolium. A heavily pretreated patient with acute promyelocytic leukemia and residual malignant cells in his marrow after multiple courses of chemotherapy was given 13-cis-retinoic acid upon demonstration of both morphologic and functional differentiation of his leukemic cells by transretinoic acid in vitro. The patient achieved a complete remission and was maintained on 13-cis-retinoic acid for 1 year, when the patient relapsed with a population of cells that were resistant to retinoic acid-induced differentiation.

Topics: Adult; Cell Differentiation; Cytarabine; Humans; In Vitro Techniques; Isotretinoin; Leukemia, Myeloid, Acute; Male; Tretinoin

An alternative to a cell-kill strategy for eradication of acute myelogenous leukemia, is to restore normal differentiation. Vitamin A derivatives demonstrate differentiation-inducing activity both in vitro and in vivo on promyelocytic leukemic cells. We tested the ability of 13-cis retinoic acid to reduce proliferation and induce differentiation in 10 samples from patients with acute non-promyelocytic leukemia. DNA synthesis and leukemia colony formation were affected to varying degrees by a prolonged exposure to the vitamin A compound. Morphologically and cytochemically no differentiation was determined either after 48 h in suspension cultures or 7 additional days in semi-solid cultures. Alkaline leukocyte phosphatase, a biochemical marker of differentiation, was significantly increased in five samples. DNA synthesis in these samples was significantly reduced as compared to samples failing to express alkaline leukocyte phosphatase following 13-cis retinoic acid treatment. DNA synthesis of these same 5 samples was also strongly inhibited by Ara-C. Expression of alkaline leukocyte phosphatase following 13-cis retinoic acid exposure may be a useful indicator for cells amenable to 13-cis retinoic acid or Ara-C treatment.

Topics: Adult; Aged; Alkaline Phosphatase; Cell Differentiation; Cell Division; Cytarabine; Female; Humans; Isotretinoin; Leukemia, Myeloid, Acute; Leukocytes; Male; Middle Aged; Thymidine; Tretinoin; Tritium