Successful eradication of chronic myeloid leukemia in a child despite allogeneic graft rejection

Background

Chronic myeloid leukemia (CML) is a rare disease in children and treated with tyrosine kinase inhibitors (TKI) and with allogeneic hematopoietic stem cell transplantation (HSCT) still in many cases.

Case

We describe an 8‐year‐old patient with CML treated with two different TKIs before proceeding to allogeneic HSCT. Despite successful engraftment, prompt rejection of the graft was followed by autologous reconstitution. TKI therapy was reintroduced post‐rejection in anticipation of relapse but shortly discontinued due to low white blood cell and neutrophil counts. The patient has remained disease‐free over 5 years after graft rejection and without further therapy.

Conclusion

This case suggests that even a short antileukemic effect by an allogeneic transplant may succeed in eradicating CML.

Novel genes involved in pathophysiology of gonadotropin-dependent adrenal tumors in mice

Specific inbred strains and transgenic inhibin-α Simian Virus 40 T antigen (inhα/Tag) mice are genetically susceptible to gonadectomy-induced adrenocortical neoplasias. We identified altered gene expression in prepubertally gonadectomized (GDX) inhα/Tag and wild-type (WT) mice. Besides earlier reported Gata4 and Lhcgr, we found up-regulated Esr1, Prlr-rs1, and down-regulated Grb10, Mmp24, Sgcd, Rerg, Gnas, Nfatc2, Gnrhr, Igf2 in inhα/Tag adrenal tumors. Sex-steroidogenic enzyme genes expression (Srd5a1, Cyp19a1) was up-regulated in tumors, but adrenal-specific steroidogenic enzyme (Cyp21a1, Cyp11b1, Cyp11b2) down-regulated. We localized novel Lhcgr transcripts in adrenal cortex parenchyma and in non-steroidogenic A cells, in GDX WT and in intact WT mice. We identified up-regulated Esr1 as a potential novel biomarker of gonadectomy-induced adrenocortical tumors in inhα/Tag mice presenting with an inverted adrenal-to-gonadal steroidogenic gene expression profile. A putative normal adrenal remodeling or tumor suppressor role of the down-regulated genes (e.g. Grb10, Rerg, Gnas, and Nfatc2) in the tumors remains to be addressed.

Transgenic GATA-4 expression induces adrenocortical tumorigenesis in C57Bl/6 mice

A link between elevated luteinizing hormone (LH) levels, GATA-4 and LH receptor (LHCGR) expression and gonadotropin-dependent adrenocortical tumorigenesis in humans and mice has been shown. To assess the mechanistic tumorigenic interrelationships between these factors, we transgenically expressed Gata4 under the 21-hydroxylase promoter (Cyp21a1, 21-OH) in C57Bl/6N mice. There was a gradual age-dependent increase of GATA-4 expression only in 21-OH-GATA-4 (TG) female adrenals, in association with slowly progressing neoplasia of non-steroidogenic spindle-shaped A cells in the subcapsular cortex. Gonadectomy (GDX), apparently through direct action of elevated serum LH, markedly enhanced the adrenocortical neoplasia, which now also appeared in GDX TG males. The neoplastic areas of the post-GDX TG adrenals contained, besides A cells, larger lipid-laden, steroidogenically active and LHCGR-positive B cells. Prolonged (>10 months) exposure to elevated post-GDX LH levels resulted in formation of adrenocortical adenomas in the TG mice. Intact and GDX TG mouse adrenals displayed elevated FOG-2 and decreased GATA-6 expression. Additionally, increased expression/activation of components of the Inhbb-Acvr2a-Acvr1c-Smad2/3 signaling system was observed in 12-month-old GDX TG adrenals. Our findings show that two distinct GATA-4-dependent populations of neoplastic adrenocortical cells form: non-steroidogenic LH-independent A cells and steroidogenic LH-dependent B cells.

Hecate-CGbeta conjugate and gonadotropin suppression shows two distinct mechanisms of action in the treatment of adrenocortical tumors in transgenic mice expressing Simian Virus 40 T antigen under inhibin-alpha promoter

Lytic peptide Hecate (23-amino acid (AA)) fused with a 15-AA fragment of human chorionic gonadotropin-beta (CG-beta), Hecate-CGbeta conjugate (H-CGbeta-c) selectively binds to and destroys tumor cells expressing LH/chorionic gonadotropin receptor (Lhcgr). Transgenic mice (6.5 month old) expressing SV40 T-antigen under the inhibin-alpha promoter (inhalpha/Tag) presenting with Lhcgr expressing adrenal tumors were treated either with H-CGbeta-c, GnRH antagonist (GnRH-a), estradiol (E(2); only females) or their combinations for 1 month. We expected that GnRH-a or E(2) in combination with H-CGbeta-c could improve the treatment efficacy especially in females by decreasing circulating LH and eliminating the potential competition of serum LH with the H-CGbeta-c. GnRH-a and H-CGbeta-c treatments were successful in males (adrenal weights 14 +/- 2.8 mg and 60 +/- 26 vs 237 +/- 59 mg in controls; P < 0.05). Histopathologically, GnRH-a apparently destroyed the adrenal parenchyma leaving only the fibrotic capsule with few necrotic foci. In females, H-CGbeta-c was totally ineffective, whereas GnRH-a (19 +/- 5 mg) or E(2) (77 +/- 50 mg) significantly reduced the adrenal weights compared with controls (330 +/- 70 mg). Adrenal morphometry, cell proliferation markers, post-treatment suppression of serum progesterone, and quantitative RT-PCR of GATA-4, Lhcgr, and GATA-6 further supported the positive outcome. H-CGbeta-c selectively killed the Lhcgr expressing tumor cells, whereas GnRH-a blocked tumor progression through gonadotropin suppression, emphasizing the gonadotropin dependency of these adrenocortical tumors. If extrapolated to humans, H-CGbeta-c could be considered for the treatment of gonadotropin-dependent adrenal tumors in males, whereas in females gonadotropin suppression, but not H-CGbeta-c, would work better.

Targeted therapy for adrenocortical tumors in transgenic mice through their LH receptor by Hecate-human chorionic gonadotropin beta conjugate

Novel strategies are needed for the treatment of adrenocortical tumors that are usually resistant to chemotherapy. Hecate, a 23-amino acid lytic peptide, was conjugated to the 15-amino acid (81-95) fragment of the human chorionic gonadotropin beta (CGbeta) chain, which would selectively kill cancer cells expressing the LH receptor (LHR) sparing the normal ones with LHR. To prove the principle that Hecate-CGbeta conjugate may eradicate tumors ectopically expressing plasma membrane receptors, transgenic (TG) inhibin alpha-subunit promoter (inhalpha)/Simian Virus 40 T-antigen mice, expressing LHR in their adrenal gland tumors, were used as the experimental model. Wild-type control littermates and TG mice with adrenal tumors were treated with either Hecate or Hecate-CGbeta conjugate at the age of 6.5 months for 3 weeks and killed 7 days after the last treatment. The Hecate-CGbeta conjugate reduced the adrenal tumor burden significantly in TG male but not in female mice, in comparison with Hecate-treated mice. Hecate-CGbeta conjugate treatment did not affect normal adrenocortical function as the serum corticosterone level between Hecate and Hecate-CGbeta conjugate groups were similar. The mRNA and protein expressions of GATA-4 and LHR colocalized only in tumor area, and a significant downregulation of gene expression was found after the Hecate-CGbeta conjugate in comparison with Hecate- and/or non-treated adrenal tumors by western blotting. This finding provides evidence for a selective destruction of the tumor cells by the Hecate-CGbeta conjugate. Hereby, our findings support the principle that Hecate-CGbeta conjugate is able to specifically destroy tumor cells that ectopically express LHR.

Adrenocortical tumorigenesis, luteinizing hormone receptor and transcription factors GATA-4 and GATA-6

Luteinizing hormone (LH/hCG) responsiveness of normal and pathological human adrenal glands as well as the possibility of constitutive expressions of luteinizing hormone receptor (LHR) in adrenal cortex has been reported. Some recent studies showed a correlation between the LHR and abundant GATA-4 expression in both metastasizing and non-metastasizing human adrenocortical tumors, but not in normal adrenals, implicating the putative relevance of LHR and GATA-4 for adrenocortical pathophysiology. However, the physio- and pathophysiological significance of LHR and GATA-4 in the mechanism of adrenocortical tumorigenesis remains unclear. The paucity of suitable models for adrenal tumorigenesis makes the establishment of proper animal models highly important. LHR expression in the murine adrenal gland is an exception and not found in wild-type (WT) animal. We have previously shown that ectopic LHR expression in the murine adrenal gland can be induced by chronically elevated LH levels. We have generated a gonadotropin-responsive adrenal tumor model in gonadectomized transgenic (TG) mice expressing the inhibin alpha promoter/Simian Virus 40 T antigen transgene (inhalpha/Tag). Given the induction of expression and regulation of GATA-4 and GATA-6 zinc finger transcription factors in the gonads by gonadotropins, this review will explore their relationship to LHR expression and their role in adrenocortical tumorigenesis. A functional link between LHR and GATA-4 actions in the adrenal pathophysiology is proposed.

Use of hecate-chorionic gonadotropin beta conjugate in therapy of lutenizing hormone receptor expressing gonadal somatic cell tumors

Improvement of cancer treatment is a major challenge of medical research. Despite the immense efforts made in the improvement of diagnosis and treatment, cancer remains a major concern and cause of morbidity and mortality. Most of the modern anti-neoplastic therapies have severe side effects, and tumor cells often develop drug resistance. There is promise in the new generation of treatments (gene therapy, immunotherapy, vaccines, etc.) that are under development, but the efficacies and side effects of such therapies have so far been disappointing. Receptor-based therapies are not new, but many normal cells also present the same receptors reducing the specificity of such approaches. Several lytic peptides have been investigated because of they appear to kill cancer cells due to changes of their membrane potential. Thus, linking receptor-specific ligands to lytic peptides is expected to augment the specificity of targeting and decrease the toxicity of lytic peptides on normal cells. One such polypeptide is hecate (an analogue to the bee venom main component, melittin) that preferentially kills cancer cells at low doses. When this peptide is fused with the 81-95 amino acid fragment of chorionic gonadotropin-beta (CGbeta) subunit (hecate-CGbeta), it targets cells expressing luteinizing hormone receptor (LHR), even at very low doses, or when LHR is expressed at low level. Our recent data showed that this peptide conjugate is efficient in destroying LHR-positive cells in xenografts and more importantly in transgenic mouse models developing LHR-positive somatic cell tumors in gonads. The mechanism of action of hecate-CGbeta after binding to LHR is destruction of cell membranes resulting in rapid cell death by necrosis with minimal side effects. This review summarizes our findings on the action of this novel peptide and considers the future potential of this family of targeting peptides in the treatment of neoplasias.