Letter: Blast-cell transformation in chronic granulocytic leukaemia

Lymphoblastic transformation of Ph1-positive chronic myeloid leukaemia: therapeutic implications and relevance to haemopoietic stem cell theory

A proportion of patients with blast crisis of CML have blast cells identical to those found in common non-T, non-B all, and whilst this disease is often referred to as lymphoid blast crisis (LBC), evidence is presented that it may in fact arise from a prelymphoid, pre-myeloid (pluripotential) stem cell. Recently developed membrane and enzyme markers (anti-ALL antiserum, TdT assay) have provided convenient diagnostic tests for the detection of LBC. The clinical and haematological features of LBC are reviewed: patients with LBC show a higher response rate to therapy with vincristine and prednisolone, and their survival may be significantly prolonged. The frequent occurrence of meningeal leukaemia suggests the need for prophylactic CNS therapy in LBC patients achieving remission.

The management of adult acute lymphoblastic leukaemia

The important advances made in recent years in the therapy of adult ALL have been reviewed. The definition of bad-prognosis patients has been improved and includes those with T-ALL, ABLL, and Ph1+ALL, in addition to those presenting with evidence of extensive disease. In contrast to childhood ALL, induction chemotherapy should include another drug (or drugs) in addition to VCR and prednisolone, and one of the anthracycline drugs (ADR or DNR) has been employed most frequently in this context. Such therapy should result in a CR rate of 70 to 75%. Similar to the experience in childhood ALL, the improvement in haematological response rate has led to an apparent increase in CNS leukaemia, and the need for adequate CNS prophylaxis is stressed. Despite these improvements, the outlook for adults with ALL is not yet as good as it is for childhood ALL. Controlled studies involving large numbers of patients are urgently needed to provide answers to a number of questions. In induction therapy, the use of higher drug dosage, the use of more and other drugs, and the use of an individual patient's risk factors to determine drug dosage, must be assessed. The benefits of consolidation therapy and the optimal duration and intensity of maintenance therapy have yet to be established. Methods of CNS prophylaxis other than cranial irradiation and IT MTX must be carefully studied. These important questions require that adult patients with ALL should be concentrated in centres capable of providing optimal overall care and, at the same time, able to conduct the necessary clinical trials.

The Philadelphia chromosome (Ph1) in adults presenting with acute leukaemia: a comparison of Ph1+ and Ph1-patients

To evaluate the frequency and clinical significance of the Philadelphia chromosome (Ph1) in adult acute leukaemia, bone marrow chromosomes were studied in 15 adults with acute lymphocytic leukaemia (ALL) and 55 with acute nonlymphocytic leukaemia (ANLL). Morphology, clinical findings, therapeutic response and survival were compared in patients with and without the Ph1. The Ph1 was found in six newly diagnosed adults presenting with ALL. Adults with Ph1+ ALL differed from those with Ph1-ALL in being older, in having more frequent lymphadenopathy and splenomegaly and in demonstrating higher initial leucocyte counts and more peripheral blasts. Complete remissions were obtained in all nine adults with Ph1-All but in only three of six with Ph1+ ALL. Adults with Ph1-ALL survived significantly longer. Four adults with ANALL were Ph1+. They did not respond to treatment and survived significantly shorter periods than adults with Ph1-ANLL. No clinical or morphologic features indicated which patients with acute leukaemia would have the Ph1. Since the presence of the Ph1 in acute leukaemia has therapeutic and prognostic significance, marrow chromosome studies should be performed in adults presenting with acute leukaemia, especially ALL.