1. ¹Department of Cellular Biotechnology and Haematology, 'La Sapienza' University, Rome, Italy
2. ²Department of Clinical and Biological Science, 'San Luigi Gonzaga' Hospital, University of Turin, Orbassano, Italy
3. ³Unit of Internal Medicine 1, Azienda Ospedaliera S Antonio Abate, Gallarate, Italy
4. ⁴Department of Haematology, Pediatric Hospital 'Bambino Gesù', Vatican City, Italy
5. ⁵Institute of Haematology, Catholic University of 'Sacro Cuore', Rome, Italy
6. ⁶Unit of Internal Medicine and Medical Oncology of University of Pavia, IRCCS Policlinico S Matteo, Pavia, Italy

Correspondence: Dr G Cimino, Department of Cellular Biotechnology and Haematology, University 'La Sapienza', Via Benevento 6, 00161 Rome, Italy. Fax: +39 06 4424 1984; E-mail: cimino@bce.uniroma1.it

Received 4 March 2004; Accepted 9 June 2004; Published online 19 August 2004.

Abstract

We compared quantitative reverse transcriptase polymerase chain reaction (Q-RT-PCR) to qualitative RT-PCR in determining response to therapy and predicting clinical outcome in 18 retrospectively selected patients with ALL positive for the ALL1-AF4 fusion and with frozen RNA samples collected at diagnosis and during follow-up (96 samples analysed). The ALL1-AF4 junction was detected by qualitative RT-PCR in 18 patients and by Q-RT-PCR in 17 patients (one patient harboured the rare e10-e6 ALL1-AF4 junction, which falls outside of the primer and probe location designed for the Q-RT-PCR). In three of the 12 patients negative to qualitative RT-PCR after induction therapy, a small number of ALL1-AF4 copies was detected by Q-RT-PCR. Thus nine patients were negative and eight positive. Seven of the eight positive patients suffered a relapse, including two of the three patients positive to Q-RT-PCR yet negative to qualitative RT-PCR. Moreover, we found two (5%) discordant results among the 39 follow-up tests of the nine patients who converted to a negative qualitative–quantitative PCR status. The results suggest that qualitative RT-PCR is more appropriate for the routine diagnosis of this genetic alteration. However, Q-RT-PCR is more accurate in assessing the molecular response after induction treatment and could be more useful in clinical decision-making in ALL1-AF4-positive ALL patients.