Persistence of RARa‐PML fusion mRNA detected by reverse transcriptase polymerase chain reaction in patients in long‐term remission of acute promyelocytic leukaemia

Abstract

Acute promyelocytic leukaemia (APL) is characterized by t(15;17), which results in the formation of two chimaeric genes, PML-RAR alpha and RAR alpha-PML. PML-RAR alpha transcripts have been detected in all cases of APL whilst those of RAR alpha-PML have been detected in only about 67% of cases. We have used reverse transcriptase polymerase chain reaction (RT-PCR) to detect both fusion transcripts serially in 18 patients in remission of APL after chemotherapy and bone marrow transplantation. All patients were negative for PML-RAR alpha, whereas in six patients (remission 3-9 years) RAR alpha-PML was consistently detected. Only one patient at remission showed the 5' breakpoint RAR alpha-PML, with the rest showing the 3' breakpoint 144 bp RAR alpha-PML. The level of sensitivity for detecting RAR alpha-PML was some 10-fold higher than that for PML-RAR alpha. Serial negative tests for PML-RAR alpha have been correlated with durable remissions, suggesting possible eradication of residual leukaemia in APL. Our results, however, show persistence of t(15;17) cells expressing RAR alpha-PML fusion mRNA in patients in long-term remission of APL. They indicate that patients considered clinically 'cured' of APL still have molecular evidence of minimal residual disease and also provide further insight into the biology of acute myeloid leukaemia.

Standardization and quality control studies of ‘real-time’ quantitative reverse transcriptase polymerase chain reaction of fusion gene transcripts for residual disease detection in leukemia – A Europe Against Cancer Program

“…24 However, 'end point' PCR analyses do not permit precise quantification of MRD levels. This limitation was underlined by the finding of low levels of AML1-ETO, 25,26 CBFB-MYH11 1 or PML-RARA 1,27 transcripts in patients in long-term clinical remission and by the detection of BCR-ABL mRNA at very low levels in healthy individuals. 28,29 Quantitative PCR analysis has been achieved by competitive PCR.…”

RT-PCR method with increased sensitivity shows persistence of PML-RARA fusion transcripts in patients in long-term remission of APL

“…These results are in keeping with our previous work which showed that some APL patients in long-term remission are positive for the reciprocal fusion gene RARA-PML transcripts. 6 Although a number of groups have worked on improving the sensitivity of PML-RARA amplification, 19,20 this study is the first to show that improving method sensitivity could detect the persistence of PML-RARA transcripts in patients in longterm remission.…”

“…1 This translocation fuses the PML gene on 15q and RARA gene on 17q to produce two transcriptionally active fusion genes PML-RARA and RARA-PML. [2][3][4][5][6] Transcripts for PML-RARA were detected in all patients with t(15;17) while RARA-PML transcripts were detected in approximately 70% of cases. 4 RT-PCR methods developed for the amplification of PML-RARA transcripts have been used for diagnosis and in monitoring minimal residual disease (MRD).…”

“…4 RT-PCR methods developed for the amplification of PML-RARA transcripts have been used for diagnosis and in monitoring minimal residual disease (MRD). 4,[6][7][8][9][10][11][12][13] However, although serial negative tests for PML-RARA are generally associated with prolonged remission, up to 25% of those patients could relapse within a short period after testing negative. 7,9,12,13 This is due to the fact that current RT-PCR methods have a sensitivity not higher than 10 −4 , which is 2 logs lower than corresponding methods for other fusion genes.…”

The role of bone marrow transplantation in acute promyelocytic leukemia

“…[41][42][43] However, this correlation is not absolute as some patients who are PCR positive remain in long-term remission, and others ultimately relapse after a negative test. [44][45][46] Although assessment of the PCR status immediately following the end of consolidation has little prognostic value, subsequent monitoring during the early post-treatment period appears informative and affects management of this disease. Recently, Diverio and colleagues 42 reported the results of a prospective study in which 163 patients who were induced into remission with ATRA combined with chemotherapy were tested at regular pre-established time intervals after the end of treatment.…”