USAGE OF DIFFERENTIATION THERAPY AND CLINICAL IMPACTS ON ACUTE PROMYELOCYTIC LEUKEMIA (APL)

Group Members :

• Farrah Azween binti Aminuddin

• Fatihah binti Mohd Yusof

•Lydia Amani binti Mohd Rasip

•Mawaddah binti Shamsudin

•Nesamalar Mohankumar

•Nur Fatihah binti Mohd Arnawi

•Yaashviny Nair

• An approach for treatment of advanced cancers in which malignant cells

are encouraged to differentiate into more mature forms by using

pharmacological agents.

• The differentiation therapy agents: all-trans-retinoic acid (ATRA) &

arsenic trioxide (ATO) in the treatment of acute promyelocytic leukemia

(APL) (Estey et al. 2015). Recently, ATRA is the inducer that is most

commonly used.

• Theoretically, the concept of differentiation therapy involves turning a

cancer cell ‘off’ biologically and reverting to a more ‘benign’

phenotype.

• Since 1980s, differentiation therapy has been a successful clinical

application in one subtype of acute myeloid leukemia (AML), which is the

APL (Petrie, Zelent & Waxman 2009).

Enhance recruitment of transcriptional repressors known as

Co-R (co-repressor complexes)

Reciprocal chromosomal translocation t(15;17)

Fusion of RARα (receptor) + promyelocytic leukemia gene (PML)

Enhance DNA hypermethylation & histone deacetylation

No gene expression and transcription

No programmed cell death (apoptosis), cell maturation and terminal differentiation

Cells keep proliferating (malignancies)

HOW ACUTE PROMYELOCYTIC LEUKEMIA (APL) DEVELOPS INSIDE PATIENTS?

(Gocek & Marcinkowska 2011)

Binds to RARA-PML heterodimer Dissociation of Co-R complexes Repressors are interchanged with co-activators complex (CoA), containing histone acetyl-

transferase (HAT) Acetylated histones cause chromatin de-condensation Leads to activation of transcription Hence, cell maturation and terminal differentiation of APL cells into granulocytes can

proceed PML-RARA fusion protein is found to undergo degradation by either ubiquitination,

sumoylation or autophagy when ATRA is combined with another differentiating agent, arsenic trioxide (ASO)

HOW DOES DIFFERENTIATION THERAPY INVOLVE IN TREATING APL

Implementation of cell differentiating agent called

ATRA (All-trans retinoid acid)

(Gocek & Marcinkowska 2011)

Figure 1: PML-RAR-α-mediated transcriptional repression, RA-induced activation, and differentiation therapy used for curing treatment

(Ablain & de The 2011)

Figure 2: A revised model of treatment outcomes in APL

(Ablain & de The 2011)

POSITIVE IMPACTS 1. Facilitated to cure fatal diseases such as APL and sarcoma

• The usage of ATRA which is an agent of the differentiation therapy. ≥90% of the patients applied with such a therapy leads to the complete remission

• Cause the chromatin structure to relax, transcriptional repression relieved, and APL cells undergo terminal differentiation into granulocytes .

• Combination of ATRA with ASO has further improved the curability of the patients with APL (Nowak et al. 2015).

2. The differentiation therapy will exhibit less toxicity compared to other cancer therapies

• Cancer therapy is highly toxic and non specific due to usage of natural products from the plants.

• IFN-β and mezerein (MEZ) which is anti-leukemic compound (less toxicity) results in irreversible growth arrest, altered cellular morphology (Leszczyniecka et.al 2001)

• Headache, mucocutaneous dryness, and hypertriglyceridemia. The only acute toxicity in study was headache, which was similar to that reported for acute vitamin A intoxication.)

3. Prevent from bone marrow and fatal hemorrhagic syndrome by minimizing residual diseases

• Malignancy medicines, including chemotherapy and radiation treatment can influence the bone marrow.

• (ATRA) can specifically incite terminal separation of promyelocytic leukemic cells into ordinary granulocytes without causing bone marrow hypoplasia (Johnson et al. 2015)

• Prevent hemorrhagic disorders from chemotherapy.

Figure 3: Differentiation of human melanoma cell

RELAPSE OCCURRENCE WITH ATRA TREATMENT ALONE • Approximately 10% to 30% of patients who were treated with ATRA alone experienced relapse

after complete remission (Asou et al. 2007).

• Short duration of the remissions with continuous ATRA therapy alone.

• Relapse occurs shortly after ATRA withdrawal indicating that post remission chemotherapy is essential to obtain long-term survival.

COMMON SIDE EFFECT • Symptom: dryness of skin and mucosa, hypertriglyceridemia (de-Medeiros et al. 1998)

RETINOIC ACID SYNDROME (RAS) • Retinoic acid syndrome (RAS) is the most severe side effect of ATRA

• Symptom: Fever, weight gain, cardiopulmonary symptoms, and renal failure

• Negative culture tests in the urine, hemoglobinuria

• Hemoglobinuria: a condition in which the oxygen transport protein hemoglobin is found in abnormally high concentrations in the urine (Moresco et al. 2011).

• Rate of death incidences 5% - 10%

• Not recommended for patients with hepatic and renal dysfunction.

NEGATIVE IMPACTS

Cases of APL that developed acute renal failure during ATRA and concurrent use of

fluconazole

14 year old girl admitted to the hospital

Could not evaluate the PML-RARA translocation by FISH or other molecular

techniques

ATRA therapy was started

Some myelocytic differentiation initiated, nonetheless she had fever again

ATRA was stopped

4 months after the diagnosis she died from febrile neutropenia and sepsis.

(Yarali et. al 2008)

SUCCESSFUL CASES

• In 1992, it was reported that Ailing-1, traditional Chinese medicine containing high levels of arsenic trioxide (ATO), induced dramatic remissions in APL patients, even those that had relapsed and were resistant to ATRA treatment (Xu et al. 2014)

•Differentiation therapy of APL has subsequently undergone further refinements and results from 2007 show that up-front use of ATRA/ATO plus induction chemotherapy leads to complete remission rates in excess of 93% with these patients achieving 5-year overall survival rates approaching 100% (Leszczyniecka et al. 2001)

SUCCESSFUL CASES (cont.)

• According to The New England Journal of Medicine, a study was conducted on how patients responded to Differentiation Therapy.

• 11 patients with APL were treated with ATRA (orally) and 9 of 11 patients went through complete remission. Studies on cellular morphology, cell-surface immuno-phenotypic analysis and FISH with chromosome 17 probe showed the correlation with maturation of leukemic cells.

• These 9 patients showed a significant decrease in the abnormal RAR-α as they went through complete remission. Patients who went through cytogenetic remission however, still had these abnormal RAR-α.

(The New England Journal of Medicine 2015)

CHALLENGES OF USING DIFFERENTIATION THERAPY IN TREATING APL

In early phase, studies combining ATRA with induction chemotherapy have yielded controversial results at which several large randomized trials failed to observe an advantage to adding ATRA to induction chemotherapy.

Early death

- due to disseminated intravascular coagulation (DIC), fibrinolysis, and proteolysis.

- Bleeding is a common clinical manifestation(Park,M.D,2014)

Differentiation syndrome (DS)

- life threatening complication of therapy with differentiating agents

- occurs during induction therapy with differentiating agents while leukemic blasts are massively present (NCBI,2014)

ATRA as a single agent cannot maintain remission and almost all APL patients routinely relapse within three months to one year

- Therefore, ATRA-induced CR is now combined with chemotherapy (i.e. anthracyclines) leads to long term survival.(M.D , Anderson , 2008)

Figure 4 : Bleeding in APL (Park 2014)

Figure 5: Signs and symptoms of DS (Park,2014)

FUTURE DIRECTION OF DIFFERENTIATION THERAPY

Revision of the prevailing conception that differentiation is a unidirectional process

- Dedifferentiate adult somatic cells to “inducible pluripotent stem cells” (IPS cells) by forced expression of 4 transcription factors (Park ,MD ,2014)

Liposome incorporated ATRA

- Inhibit cell proliferation and induce high level apoptosis not only in APL cell but also in NHL-B cells

- 300 times efficient than free ATRA (Douer, 2006)

Arsenal and interrogational power of molecular methods

- Aberrant epigenetic profiles in cancer are assessed with whole-genome CpG methylation and histone modification array techniques

- Genes identified analyzed for their function in murine knockout systems (Park & MD,2014)

CONCLUSION

To sum up, differentiation therapy has tremendously emerged as a promising method to replace other highly toxic and ineffective protocols for treating cancer. It is done by using ATRA as the primary differentiating agent. Despite challenges faced, the benefits of this therapy compared to others, carry more weight. Therefore, more innovative approaches are being developed to enhance the standards of differentiation therapy not only to cure the APL disease, but also other cancers.

THANK YOU!

If you have any questions, please ask us in the forum

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