Chronic myeloid leukemia (CML) is a hematological cancer, characterized by a reciprocal chromosomal translocation between chromosomes 9 and 22 [t(9;22)], producing the Bcr-Abl oncogene. Tyrosine kinase inhibitors (TKIs) represent the standard of care for CML patients and exert a dual mode of action: direct oncokinase inhibition and restoration of effector-mediated immune surveillance, which is rendered dysfunctional in CML patients at diagnosis, prior to TKI therapy. TKIs such as imatinib, and more potent second-generation nilotinib and dasatinib induce a high rate of deep molecular response (DMR, BCR-ABL1 ≤ 0.01%) in CML patients. As a result, the more recent goal of therapy in CML treatment is to induce a durable DMR as a prelude to successful treatment-free remission (TFR), which occurs in approximately half of all CML patients who cease TKI therapy. The lack of overt relapse in such patients has been attributed to immunological control of CML. In this review, we discuss an immunological timeline to successful TFR, focusing on the immunology of CML during TKI treatment; an initial period of immune suppression, limiting antitumor immune effector responses in newly diagnosed CML patients, linked to an expansion of immature myeloid-derived suppressor cells and regulatory T cells and aberrant expression of immune checkpoint signaling pathways, including programmed death-1/programmed death ligand-1. Commencement of TKI treatment is associated with immune system re-activation and restoration of effector-mediated [natural killer (NK) cell and T cell] immune surveillance in CML patients, albeit with differing frequencies in concert with differing levels of molecular response achieved on TKI. DMR is associated with maximal restoration of immune recovery in CML patients on TKI. Current data suggest a net balance between both the effector and suppressor arms of the immune system, at a minimum involving mature, cytotoxic CD56dim NK cells may be important in mediating TFR success. However, a major goal remains in CML to identify the most effective pathways to target to maximize an advantageous immune response and promote TFR success.
Immune Effector Recovery in Chronic Myeloid Leukemia and Treatment-Free Remission
Posted 17 May 2017 - 07:26 PM
CML patients with deep molecular responses to TKI have restored immune effectors and decreased PD-1 and immune suppressors.
Immunological control may contribute to achievement of deep molecular response in chronic myeloid leukemia (CML) patients on tyrosine kinase inhibitor (TKI) therapy and may promote treatment-free remission (TFR). We investigated effector and suppressor immune responses in CML patients at diagnosis (n = 21), on TKI (imatinib, nilotinib, dasatinib) before achieving major molecular response (pre-MMR, BCR-ABL1 >0.1%, n = 8), MMR (BCR-ABL1 ≤0.1%, n = 20), molecular response4.5 (MR4.5, BCR-ABL1 ≤0.0032%, n = 16), and sustained TFR (BCR-ABL1 undetectable following cessation of TKI therapy, n = 13). Aberrant immune-inhibitory responses (myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs), and programmed death-1 (PD-1) inhibitory molecule expression on CD4+/CD8+ T cells were increased in CML patients at diagnosis. Consequent quantitative and functional defects of innate effector natural killer (NK) cells and cytotoxic T-lymphocyte responses to leukemia-associated antigens WT1, BMI-1, PR3, and PRAME were observed at diagnosis. Treg and PD-1+CD4+/CD8+ T cells persisted in pre-MMR CML patients on TKI. Patients in MMR and MR4.5 had a more mature, cytolytic CD57+CD62L− NK cell phenotype, consistent with restoration of NK cell activating and inhibitory receptor repertoire to normal healthy donor levels. Immune responses were retained in TFR patients off-therapy, suggesting the restored immune control observed in MMR and MR4.5 is not an entirely TKI-mediated effect. Maximal restoration of immune responses occurred only in MR4.5, as demonstrated by increased NK cell and effector T-cell cytolytic function, reduced T-cell PD-1 expression and reduced numbers of monocytic MDSCs.
Posted 18 May 2017 - 07:24 PM
Thanks for these, Gerry. So helpful.
Dx July 2009 on routine physical. WBC 94. Started Gleevec 400 mg Sept 2009. MMR at 2yrs. Side effects (malaise, depression/anxiety, fatigue, nausea, periorbital edema) never improved. Kidney issues developed because of Gleevec. Switched to Sprycel 70 mg in Aug 2011. Above side effects disappeared or improved. Have been MR3.5 - 4.5 ever since. Two untreated pleural effusions followed by one treated by stopping Sprycel Jan 2017. After 9 weeks, PCR showed loss of MMR; re-started Sprycel at 50 mg and in 3 months was back to <0.01% IS. Pleural effusion returned within a couple of months, same as before (moderate, left side only). Stopped Sprycel 50 mg for 12 weeks; pleural effusion resolved. At about a monthoff the drug, PCR was 0.03; at 11 weeks it was 2.06 - lost CCyR? Have returned to 50 mg Sprycel for 3 weeks, intending to reduce to 20 mg going forward.
Posted 18 May 2017 - 09:19 PM
BMB 9:22 translocation
1/19/15 began 400 mg gleevec
1/22/15 bcr 37.2 IS
2/6/15 bcr 12.5 IS
3/26/15 bcr 10.3 IS
6/29/15 bcr 7.5 IS
9/24/15 bcr 0.8 IS
1/4/16 bcr 0.3 IS
Started 100 mg dasatinib, mutation analysis negative
4/20/16 bcr 0.03 IS
8/8/16 bcr 0.007 IS
12/6/16 bcr 0.002 IS
Lowered dasatinib to 70 mg
4/10/17 bcr 0.001 IS
Lowered dasatinib to 50 mg
7/5/17 bcr 0.004 IS
8/10/17 bcr 0.001. Stopped TKI in prep for September surgery.
9/10/17 bcr 0.006
10/10/17 bcr 0.088
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