If it is really JMML, this is an MDS/Myeloproliferative syndrome. In the US, if there are more than 20% blasts, this is treated like acute leukemia, with cytarabine and an anthracycline, followed by stem cell transplant. The drugs you mention are for chronic myeloid leukemia or Acute lymphocytic leukemia with the bcr/abl translocation.  Sometimes there is confusion with bcr/abl transformed to either AML or ALL, which should be treated with imatinib or dasatinib or nilotinib.  It has activation of Ras.  A pediatric hematologist might have a better sense for this.  

 I did a quick search on Pubmed and attached this. 

Allogeneic stem cell transplant is a treatment of choice. Cure is unlikely without transplant

In molecular screening on NRAS, KRAS, PTPN11, and CBL gene mutation, if there is NRAS mutation (17 % of patients ), observation is mandatory and very possibly gets a spontaneous cure. Otherwise, SCT is needed.

If you think the patient needs induction chemotherapy, I think that modified AtV regimen (Kang HJ, Shin HY, Choi HS, et al. Leuk Res 2004;28(2):167-70.) is the most feasible regimen till now. Of course, allogeneic SCT is mandatory.

Allogeneic stem cell transplant, preferred prep has been iv busulfan/melphalan.  Transplant early to avoid induction chemo if possible that increases toxicity and often has limited success improving transplant outcome.

You really need to confirm JMML. If the patient is positive for bcr- abl then its not JMML and using Imatinib/ Dasatinib is justified. They don't have any role in JMML. Allo- SCT is the only curative option. We often use a combination of oral cytotoxic "metronomic" chemotherapy to cytoreduce the counts and keep splenomegaly in check as a bridge to transplant as arranging finances and support for SCT, along with a long waiting period is often an issue with our patients due to resource constraints. This approach doesn't compromise our transplant success when it does take place

In JMML the only cure for most patients is allogeneic stem cell transplant. Exceptions are some patients with Noonan syndrom and JMML like disease in which cases of spontaneous resolution is well documented. There is also some evidence that RAS mutations can be associated with favorable outcome and that it may not be mandatory with HSCT in some of these patients. However, at present there is no consensus regarding genotype-based management so HSCT is the treatment of choice for the majority of patients.

There is no evidence that any pharmacological intervention prior to HSCT improves outcome but 6-mercaptopurin is most commonly employed in Europe in cases with acute life-threatening disease (eg severe hyperleukocytosis and pulmonary problems) while waiting for HSCT.

First: does the patient have the fusion gene BCR-ABL positive?

Cytogenetics?

If so, I suggest you reconsider the diagnosis.

Once you have it clarified, ask again.

BCR-ABL-Negative.

There's an article this month in Blood:

How I treat juvenile myelomonocytic leukemia (JMML).

Locatelli F1, Niemeyer CM2.

Author information:

1Department of Pediatric Hematology-Oncology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Bambino Gesu Children's Hospital, Rome, Italy; [email protected].

2Division of Pediatric Hematology and Oncology, Department of Pediatrics, University of Freiburg, Germany.

Ask the author for the article or opinion.

Here´s the link:

http://www.bloodjournal.org/content/early/2015/01/06/blood-2014-08-550483

I hope you obtain the best information.

Hi

in my opinion, the best treatment for JMML is HSCT

chemotherapy alone is not effective lifelong

Please confirm diagnosis of JMML. You would need molecular testing to confirm the alternative differential diagnosis of pediatric CML (test for BCR-ABL). After that if patient satisfies the criteria for JMML (available in most oncology books) as mentioned by other members above, allogeneic SCT is the only curative option for JMML. If for some reason, early transplant is not possible and patient needs cyto-reduction for acute life-threatening symptoms then oral 6-MP may be tried as a short bridge to transplant.

Thank you Vasant.

I Agree, the best therapy is allogenic SCT, although the results are not very good. In our short experience (only one case) oral 6-MP work as a bridge to transplant. 

TKI not a option for JMML.