This document summarizes the usage of differentiation therapy in treating acute promyelocytic leukemia (APL). It discusses how APL develops, how differentiation therapy works to treat it using all-trans retinoic acid and arsenic trioxide, and the positive and negative impacts of this therapy. It also reviews successful case studies and challenges, as well as the future direction of differentiation therapy.

1. USAGE OF DIFFERENTIATIONTHERAPY
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

2. • 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).

3. 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)

4.  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 DIFFERENTIATIONTHERAPY INVOLVE INTREATING
APL
Implementation of cell differentiating agent
called
ATRA (All-trans retinoid acid)
(Gocek & Marcinkowska 2011)

5. Figure 1: PML-RAR-α-mediated transcriptional repression, RA-induced activation,
and differentiation therapy used for curing treatment
(Ablain & deThe 2011)

6. Figure 2: A revised model of treatment outcomes in APL
(Ablain & deThe 2011)

7. 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.)

8. 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

9.  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

10. 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)

11. 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)

12. SUCCESSFUL CASES (cont.)
• According to The New England Journal of Medicine, a study was conducted
on how patients responded to DifferentiationTherapy.
• 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)

13. 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)

14. Figure 4 : Bleeding in APL
(Park 2014)
Figure 5: Signs and symptoms of DS (Park,2014)

15. 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)

16. 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.

17. THANK YOU!
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please ask us in the forum 

18. 1. Ablain, J & de The, H 2011, ‘Revisiting the differentiation paradigm in acute promyelocytic
leukemia’, Blood, issue. 22, vol. 117, pp. 5795-5802.
2. Asou, N, Kishimoto, Y, Kiyoi, H, Okada, M, Kawai, Y, Tsuzuki, M, Horikawa, K, Matsuda, M,
Shinagawa, K, Kobayashi, T, Ohtake, S, Nishimaru, M, Takahashi, M, Yagasaki, F, Takeshita, A,
Kimura, Y, Iwanaga, M, Naoe, T & Ohno, R 2007, ‘A randomized study with or without intensified
maintenance chemotherapy in patients with acute promyelocytic leukemia who have become
negative for PML-RARα transcript after consolidation therapy: The Japan Adult Leukemia Study
Group (JALSG) APL97 study’, Blood, vol. 110, no. 1, viewed 15 September 2015,
<http://www.bloodjournal.org/content/110/1/59?sso-checked=true>.
3. Cabral, R, Caballero, JC, Alonso, S, Davila, J, Cabrero, M, Caballero, D, Vazquez, L, Sanchez-
Guijo, F, Lopez, L, Canizo, MC, Mateos, MV & Gonzalez M 2014, Late differentiation syndrome
in acute promyelocytic leukemia: a challenging diagnosis, Hematology Reports, vol. 6, pp. 75-
77.
4. de-Medeiros, BC, Strapasson, E, Pasquini, R & de-Medeiros, CR 1998, ‘Effect od all-trans
retinoic acid on newly diagnosed acute promyelocytic leukemia patients: results of a Brazillian
center’, Brazillian Journal of Medical and Biological Research, vol. 31, pp. 1537-1543.
5. Douer, D 2006, 'ATO: The Forefront Of APL Treatment?', viewed 9 September 2015,
<http://www.bloodjournal.org/content/107/7/2588?sso-checked=true>.
6. Estey, E, Manero, GG, Ferrajoli, A, Faderl, S, Verstovsek, S, Jones, D & Katarjian H 2015,
‘Use of all-trans retinoic acid plus arsenic trioxide as an alternative to chemotherapy in
untreated acute promyelocytic leukemia’, viewed 7 September 2015,
<http://www.bloodjournal.org/content/bloodjournal/107/9/3469.full.pdf?sso-checked=true>.
7. Gocek, E & Marcinkowska, E 2011, ‘Differentiation Therapy of Acute Myeloid Leukemia’,
Cancers, pp. 2402-2420.
REFERENCES

19. 8. Johnson, DE & Redner, RL 2015, ‘An ATRActive future for differentiation therapy in APL’,
Blood Reviews, vol. 29, pp. 263-268.
9. Leszczyniecka, M, Roberts, T, Dent, P, Grant, S & Fisher, PB 2001, ‘Differentiation therapy
of human cancer: basic science and clinical applications’, Pharmacology and Therapeutics,
vol. 90, pp. 105-156.
10. Moresco, G, Martinello, F & Souza, LC 2011, ‘Acute renal failure in patient treated with
ATRA and amphotericin B: case report’, J Bras Nefrol, vol. 33, no. 2, pp. 276-281.
11. Nowak, D, Stewart, D & Koeffler, HP 2015, ‘ Differentiation Therapy of Leukemia: 3 decades
of development’, Blood Journal, vol.113, no.16, pp. 3655-3665.
12. Park, MD 2014, Medscape Education Oncology, viewed 9 September 2015,
<http://www.medscape.org/viewarticle/835391_transcript>.
13. Petrie, K, Zelent, A & Waxman, S 2009, ‘Differentiation therapy of acute myeloid leukemia:
past, present and future’, viewed 7 September 2015,
<http://www.ncbi.nlm.nih.gov/pubmed/19468269>.
14. The New England Journal of Medicine 2015, Differentiation Therapy of Acute Promyelocytic
Leukemia with Tretinoin (All-trans-Retinoic Acid), viewed 10 September 2015,
<http://www.nejm.org/doi/full/10.1056/NEJM199105163242002#t=articleResults>.
15. Xu, WP, Zhang, X & Xie, WF 2014, ‘Differentiation therapy for solid tumors’, Journal of
Digestive Diseases, vol.15, pp. 159-165.
16. Yarali, N, Tavil, B, Kara, A, Ozkasap, S & Tunc, B 2008, ‘Acute Renal Failure During ATRA
Treatment’, Pediatric Hematology and Oncology, vol. 25, pp. 115-118.