Treatment of hairy-cell leukaemia with alpha-interferon (alpha-IFN)

Long-term treatment of hairy cell leukemia with interferon-α: still a viable therapeutic option

Classic hairy cell leukemia (HCL) is a rare indolent B‑cell-lymphoproliferative disorder, first described as a distinct disease entity in 1958. After more than two decades without effective chemotherapeutic options and a dismal prognosis of less than 5 years, only the introduction of interferon‑α (IFN‑α) allowed for response rates between 80-90 % and survival improvement. Nowadays, however, patients are rarely treated with IFN-α as purine analogues were found to be highly effective in HCL facilitating a near normal life span in most cases. Moreover, novel therapeutic tools for patients with relapsed or refractory disease after purine analogues have emerged such as rituximab and, more recently, vemurafenib. In the absence of long-term safety data for these novel agents, however, IFN-α may still represent a viable therapeutic option when the profound immunosuppressive side effects of purine analogues are to be avoided. We herein report a HCL patient, who has received multiple lines of therapy, including pentostatin, cladribine, and a total of 164 months of treatment with IFN‑α yielding long-term disease control. Our case illustrates that long-term administration of IFN-α with adequate dose-adjustments according to toxicity and disease activity is feasible in HCL and may still be a viable therapeutic option when purine analogues are considered unsuitable.

Relationship between immunological phenotype and hematological response to alpha-IFN treatment in 35 patients with hairy cell leukemia

During the past 6 years, clinical trials employing alpha-interferon (alpha-IFN) in hairy cell leukemia (HCL) have shown dramatic improvement in the management of this disease. Complete remissions (CR), however, are relatively rare (10-15%) and a minority of patients (10-25%) do not respond adequately to alpha-IFN. The possibility that the poor response to alpha-IFN treatment could be related to a peculiar immunological phenotype of the hairy cell (HC) was investigated in this study. The results demonstrated that, in the majority of patients who failed to respond to alpha-IFN, HC showed an immunological phenotype characterized by positivity with the CD5 monoclonal antibody which is usually absent on HC and characteristically expressed on B-chronic lymphocytic leukemia cells. In fact, among the 10 HCL patients who presented with this phenotype, only 5 partial remissions (PR) and 5 minor responses (MR) were achieved, as opposed to the 3 complete remissions (CR), 19 PR and 3 MR observed in the 25 CD5-negative patients. The possibility that a more extensive immunological analysis of HCL patients at diagnosis may be predictive of the response to IFN treatment is postulated.

Pharmacological elements in clinical application of synthetic peptides

The research carried out on the biological properties of synthetic peptides and the possibility of obtaining them in adequate amounts through the recombinant DNA technology allows their use as therapeutical agents. Procedures following the synthesis of peptides must be performed in order to verify their structure, conformation, immunogenicity and biological activity and to make them suitable for clinical applications. The size of synthetic peptides together with some modifications such as amidation, acetylation and sulfatation must be taken into consideration as they may have a significant impact on half-life, stability and biological activity. Endothelial, epithelial and enzymatic interference which may hinder the absorption of drugs must be evaluated in order to choose the most appropriate route of administration. The considerable bioavailability related to the intravenous route, the effectiveness of the circulation of the intramuscular route and the possibility of reaching specific targets by the intra-arterial route must also be taken into consideration. There is the possibility of applying transdermal therapeutic systems and transdermal iontophoresis only for peptides of low molecular weight. Among synthetic peptides provided with antianaemic activity, erythropoietin, growth factors and interleukin 3 must be mentioned because of their effectiveness both in optimal stimulation of melopoiesis after chemotherapy or bone-marrow transplantation and in the treatment of anaemia occurring during chronic renal failure. Furthermore, interferon alpha was shown to be one of the most used synthetic peptides provided with antiviral and antineoplastic activity. Remarkable results have been obtained in the treatment of chronic hepatitis C, haematological malignancies and some solid tumours. More recently, interleukin 2 has been tested in the treatment of melanoma and renal cancer, inducing a reasonable proportion of overall response rate. Finally, the antagonist of gonadotropin-releasing-hormone may be regarded as effective agent both in the treatment of prostate cancer and in the inhibition of luteinizing-hormone surges during controlled ovarian stimulation. Toxic side effects can be related to the administered dose as well as to metabolites derived from bacteria in which peptides have been synthesized.

Correction of Abnormal T-Cell Receptor Repertoire During Interferon-α Therapy in Patients With Hairy Cell Leukemia

Patients with the B-cell malignancy hairy cell leukemia (HCL) exhibit a skewed T-cell repertoire with oligoclonal expression or absence of many members of the T-cell receptor (TCR) BV gene families. To evaluate whether interferon-α (IFN-α) therapy would not only restore normal hematopoiesis, but also the abnormal T-cell repertoire, we studied T lymphocytes from a cohort of HCL patients treated by IFN-α in the past, at initiation, and at several intervals up to 6 years of IFN-α treatment. The junctional regions from 22 TCRBV gene families were analyzed after polymerase chain reaction amplification of cDNA (RT-PCR) using family specific primers. In all seven patients improvement of the skewed T-cell repertoire was not seen until 2 years of treatment. It consisted of disappearance of oligoclonal subpopulations and (polyclonal) reappearance of absent TCRBV gene families. The RT-PCR results were correlated with the TCRBV protein expression using TCRBV-specific monoclonal antibodies. T lymphocytes from four patients with active HCL contained large expansions of particular TCRBV-expressing cells (up to 25% of the CD3+cells; 600 to 700/μL whole blood), which decreased during IFN-α therapy in both patients tested. Finally, restoration of the TCR repertoire matched normalization of the functional immune repertoire as measured by proliferative, helper, and cytotoxic T-lymphocyte precursor frequencies against major histocompatibility complex–unrelated individuals. In conclusion, oligoclonal bands of TCRBV gene families found by RT-PCR correspond with a dramatic increase in circulating T lymphocytes expressing the same TCRBV family. Moreover, IFN-α can restore the skewed T-cell repertoire and suppress persistent T-cell clones upon treatment of the accompanying malignancy.

T-cell dysfunction in hairy cell leukemia: an updated review

Hairy cell leukemia (HCL) is clinically associated with severe T-cell dysfunction. Several new observations have given more insight into the abnormal T-cell responses seen in this disease. T-lymphocytes in the spleen of patients with HCL seem to be abnormally activated. On the other hand, they are non-responsive, possibly as a result of monocytopenia which may lead to inadequate antigen presentation. This, together with the lack of CD28 on T-cells, may cause T-cell dysfunction. Furthermore, there is a very restricted repertoire of the T-cell receptor-beta family, which may also result in non-responsiveness. Otherwise, T-cell clonal excess may be indicative for activated, possibly autoreactive T-cells.

Correction of Abnormal T-Cell Receptor Repertoire During Interferon-α Therapy in Patients With Hairy Cell Leukemia

Patients with the B-cell malignancy hairy cell leukemia (HCL) exhibit a skewed T-cell repertoire with oligoclonal expression or absence of many members of the T-cell receptor (TCR) BV gene families. To evaluate whether interferon-α (IFN-α) therapy would not only restore normal hematopoiesis, but also the abnormal T-cell repertoire, we studied T lymphocytes from a cohort of HCL patients treated by IFN-α in the past, at initiation, and at several intervals up to 6 years of IFN-α treatment. The junctional regions from 22 TCRBV gene families were analyzed after polymerase chain reaction amplification of cDNA (RT-PCR) using family specific primers. In all seven patients improvement of the skewed T-cell repertoire was not seen until 2 years of treatment. It consisted of disappearance of oligoclonal subpopulations and (polyclonal) reappearance of absent TCRBV gene families. The RT-PCR results were correlated with the TCRBV protein expression using TCRBV-specific monoclonal antibodies. T lymphocytes from four patients with active HCL contained large expansions of particular TCRBV-expressing cells (up to 25% of the CD3+cells; 600 to 700/μL whole blood), which decreased during IFN-α therapy in both patients tested. Finally, restoration of the TCR repertoire matched normalization of the functional immune repertoire as measured by proliferative, helper, and cytotoxic T-lymphocyte precursor frequencies against major histocompatibility complex–unrelated individuals. In conclusion, oligoclonal bands of TCRBV gene families found by RT-PCR correspond with a dramatic increase in circulating T lymphocytes expressing the same TCRBV family. Moreover, IFN-α can restore the skewed T-cell repertoire and suppress persistent T-cell clones upon treatment of the accompanying malignancy.

The interferons in haematological malignancies

Interferons (IFNs) are a family of biological response modifiers with a broad spectrum of action on cellular proliferation as well as immunoregulation. In the last decade, these properties have prompted several investigations of the effect of IFNs on various haematological malignancies. IFNs-alpha have been used most extensively. The response rate is dependent on the type of the disease. The most striking effects have been observed in hairy cell leukaemia and chronic myeloid leukaemia. In both these malignancies the results are well consolidated and indicate that IFNs-alpha have modified the natural history of the disease. Results of IFN therapy in low grade lymphoma, cutaneous T-cell lymphoma and multiple myeloma suggest a beneficial role of IFNs-alpha in the induction, as well as the maintenance, phase. The efficacy of IFNs is now widely confirmed in treating patients with essential thrombocythaemia or polycythaemia vera. However, the role of IFNs in the management of chronic lymphocytic leukaemia and myelofibrosis with myeloid metaplasia is still controversial.

Rapid restoration of natural killer activity following treatment with 2-chlorodeoxyadenosine in 22 patients with hairy-cell leukemia

We report on the T-cell profile and natural killer (NK) function in 22 hairy cell leukemia patients before and 2 and 6 months after a single 7-day course of 2-CdA therapy at a dose of 0.1 mg/kg daily continuous infusion. Before treatment, two groups of patients were identified in respect to NK activity: the first (12/22) had a normal number of T and NK cells and a normal NK activity, the second (10/22) showed a severe reduction of CD3+, CD4+, CD16+, and CD56+ cells, together with impaired NK activity. All patients had increased serum levels of the soluble interleukin 2 receptor (sIL-2R). Along with a high complete remission rate (77%), treatment with 2-CdA produced a significant reduction (p = 0.001) of total lymphocytes (from 1.59 x 10(9)/l to 0.72 x 10(9)/l), and particularly of CD4+ cells (from 0.68 x 10(9)/l to 0.23 x 10(9)/l), while CD8+, CD16+ and CD56+ cells were less affected. Despite the dramatic reduction of lymphocytes which lasted for more than 6 months, 7/10 patients with impaired NK function before starting 2-CdA therapy normalized the cytotoxic function within 2 months. In conclusion, 2-CdA produces a severe reduction of lymphocytes in general, and of CD4 lymphocytes in particular, whilst it may produce a significant increase in the proportion of NK cells leading, together with a normalization of the sIL-2R serum levels, to a rapid restoration of the NK cytotoxic function in the majority of patients.

Hairy cell leukaemia

Hairy cell leukaemia is a rare chronic lymphoproliferative disease, characterized by splenomegaly, pancytopenia and recurrent infection. The characteristic 'hairy cells', present in the peripheral blood and bone marrow, are the hallmark of this leukaemia. The disease has a chronic, progressive course, and the majority of patients afflicted by it require therapy. The most common reason to initiate treatment is neutropenia with or without associated infectious complications, or the development of severe thrombocytopenia. Therapeutic options in hairy cell leukaemia include splenectomy, interferon administration, or the use of chemotherapeutic agents such as pentostatin (2'-deoxycoformycin) and 2-chlorodeoxyadenosine. Splenectomy is still indicated in the treatment of young patients with significant splenomegaly and only minimal bone marrow involvement. Interferon treatment induces remission in approximately 90% of patients with hairy cell leukaemia, but complete remission is obtained in only 5-10%. The development of antibodies against interferon was initially considered a major problem, but longer follow-up of patients who developed antibodies has shown that it is transient and does not have a significant impact on the overall response to treatment. Pentostatin induces complete remission in 60-70% of patients and partial remission in 20-40%. 2-Chlorodeoxyadenosine is a very promising drug in the treatment of this rare leukaemia, inducing long-lasting complete remission in approximately 80% of patients. While interferon does not cure the disease, it is possible that a subset of patients treated with pentostatin or 2-chlorodeoxyadenosine are cured. Longer follow-up of these patients will determine whether this is true.

High complete remission rate in hairy cell leukemia treated with 2-chlorodeoxyadenosine

2-Chlorodeoxyadenosine (2-CdA), a purine nucleoside, has been shown to be remarkably effective in the treatment of patients with hairy cell leukemia (HCL). We hereby report on the results achieved in 26 HCL patients treated with one single course of 2-CdA at a dose of 0.1 mg/kg daily for 7 days continuous infusion. Twenty-four were males and 2 females, with a median age of 56 years; all but 5 had been previously treated with Interferon-alpha (IFN-alpha). All cases are fully evaluable for their clinical and hematological response. Twenty of them (77%) achieved a complete remission and 6 a partial remission; two of the latter progressed after 6 and 12 months, respectively. The median duration of response was 13.8 months, ranging from 7 to 22 months from the end of therapy. Circulating hairy cells and spleen enlargement, when present, disappeared within 2 weeks after completing treatment; furthermore, a rapid normalization of soluble Interleukin-2 receptor serum levels was observed in all complete responders but one, and in 2 of the 6 partial responders. A significant lymphocytopenia was observed in almost all patients, whilst a severe neutropenia (< 500/microliters) was registered mainly in the 10 patients who had less than 1,000/microliters neutrophils when treatment was started; the hemoglobin and platelets were marginally affected in only a few cases. Eight of the 10 patients who developed severe neutropenia experienced fever; in 4 of them it was short-lived (24 hours) and apparently not infection-related, while the remaining 4 probably had an infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Advances in therapy for hairy cell leukemia. A review

BACKGROUND

Hairy cell leukemia (HCL) is a chronic B-cell malignancy, typically seen in middle-aged men, characterized by pancytopenia, splenomegaly, immunologic abnormalities, and morphologically typical neoplastic mononuclear cells in the blood, bone marrow, liver, spleen, and other tissues. Diagnosis is confirmed by demonstration of hairy cells in biopsy specimens from the bone marrow or spleen or in peripheral blood. The natural history of this lymphoproliferative disorder varies. Patients may die early during the initial phase of therapy; others may require no therapy; and for some, splenectomy alone, without further treatment, may suffice for many years. Recently, the nucleosides pentostatin (2'-deoxycoformycin) (DCF) and 2'-chlorodeoxyadenosine (2-CdA) have been shown to produce greater numbers of durable complete remissions with curative potential in patients with HCL. The treatment options, with emphasis on major therapeutic advances with alpha-interferon, DCF, and 2-CdA, are reviewed in this article.

METHODS

Studies on HCL published from 1958 to 1992 were reviewed using the Cancerline and Medline retrieval systems and other bibliographies.

RESULTS

Management of HCL has changed in the last decade as a result of three new effective agents: alpha-interferon DCF, and 2-CdA. DCF has produced an overall response rate of 86% and a complete remission rate of 62%. 2-CdA has yielded an overall response rate of 95% and a complete remission rate of 82%. Alpha-interferon has given an overall response rate of 82% and a complete remission rate of 8%. Other agents with limited activities include chlorambucil, cyclophosphamide, cytarabine, vincristine, doxorubicin, and zorubicin hydrochloride. The effects of lithium carbonate, immunotherapy, splenic irradiation, androgens, and leukaphoresis are minimal and transient.

CONCLUSIONS

Modern management of HCL with 2-CdA and DCF is now potentially curative rather than palliative in some patients; however, the optimal therapeutic approach remains uncertain. Alpha-interferon has been approved by the Food and Drug Administration as the first-line drug therapy, followed by DCF in non-responding patients. 2-CdA remains an experimental therapy, but its higher response rate and ease of administration may make it the first-line treatment of choice. Additional research into the biology of HCL and further clinical trials are needed to determine the optimal treatment strategy for this disorder. Therefore, the best therapeutic approach at the current time is to include patients with HCL in ongoing clinical trials.

Gene expression regulation for interferon-alpha in hepatocellular carcinoma

We investigated whether regulation of interferon-alpha gene expression could be involved in liver tumor biology and the role, if any, of hepatitis B virus in the regulation of tumor cytokine gene expression. Gene expression was investigated at the transcriptional level using 'in situ' hybridization of cytokine message with an interferon-alpha cDNA probe and at the translational level with immunohistochemistry using an immunoperoxidase technique. Compared to histologically normal liver, a greater percentage of tumor and non-tumor-involved liver tissue sections (67-80% vs. 17%) contained cells positive for interferon-alpha messenger RNA, many of which were also seen to contain an increased number of transcripts (> 100 grains/cell). Hepatitis B infection did not appear to play a role in gene activation, at the hepatocellular level, in liver disease. Except for sinusoidal cells, cells containing cytokine transcripts also produced mature immunoreactive protein. Absence of interferon-alpha protein within mononuclear and sinusoidal cells in seronegative hepatocellular carcinoma tissue with/without underlying liver disease suggested deficient cytokine gene expression, at the post transcriptional level, within these cells in this group. Bile duct epithelia in tumor tissue were found to contain immunoreactive protein for interferon-alpha. In summary our results suggest that interferon-alpha gene activation in hepatocellular carcinoma occurs as a result of the liver cell damage and does not play a dominant role in tumor biology.

Results in hairy-cell leukemia patients treated with alpha-interferon: predictive prognostic factors

Fourty-four evaluable patients with hairy cell leukemia (HCL) were treated with human lymphoblastoid alpha-interferon (alpha-IFN), at a dose of 3 x 10(6) Units a day for 12-18 months while 18 of them continued to receive a three times per week schedule at the same dose as maintenance treatment. Eighteen percent of patients achieved complete response, 64% partial response, and 18% minor response with a median duration of 37.5, 22.9 and 3.5 months respectively. Twenty patients (45%), all partial or minor responders, subsequently had progression of the disease. The progression occurred more frequently in patients who presented at diagnosis with a hairy-cell index value > 0.50 than in those who presented with a hairy-cell index < 0.50: 14/26 (54%) versus 2/11 (18%) respectively. In addition, the progression rate was more evident in "non-maintained" than in "maintained" patients: 16/26 (61.5%) versus 4/18 (22%). Restarting alpha-IFN treatment in 16 of the 20 progressed patients proved effective only in 9 of them. From these findings it appears that a low hairy-cell index at diagnosis correlates favorably with a good hematological response. Furthermore, continuous therapy with alpha-IFN seems very useful in reducing the progression of the disease, in particular in patients with a very high hairy-cell index at diagnosis.

Hairy cell leukaemia: review of treatment

The cardinal features of hairy cell leukaemia are: (i) cytopenias, (ii) splenomegaly, and (iii) mononuclear cells of B-cell origin with cytoplasmic projections and tartrate-resistant acid phosphatase-positivity. The most common complication is infection. In the past, the mainstay of therapy has been splenectomy, and this procedure is still often suggested as a first-line approach. However, research during the last decade has resulted in three new, highly effective therapies for hairy cell leukaemia: interferon-alpha (IFN-alpha), 2'-deoxycoformycin (DCF) and 2-chlorodeoxyadenosine (2CDA). IFN-alpha is currently approved for this indication. About 90% of patients have a durable haematologic recovery, and complete remission rates range from less than 5% to greater than 40% in different series. It should be noted that patients with partial remissions generally have normal or near-normal blood counts, and can live indefinitely without disease-related problems, despite a few remaining hairy cells in the bone marrow. In this paper we will discuss the various therapeutic modalities available for patients with hairy cell leukaemia.

Selection of a panel of monoclonal antibodies for monitoring residual disease in peripheral blood and bone marrow of interferon-treated hairy cell leukaemia patients

A panel of monoclonal antibodies (mAbs) directed against B-cell and hairy cell leukaemia (HCL)-associated antigens was used to identify residual hairy cells in the peripheral blood and/or bone marrow samples from 20 patients with HCL, following treatment with interferon-alpha (IFN-alpha) or interferon-beta (IFN-beta). In all cases, hairy cells retained their characteristic phenotype, e.g. positivity for CD22, CD11c, CD25, CD32, and the HCL-associated trimeric protein (t-GP) recognized by the mAbs HML-1, B-ly7, LF61 and Ber-Act8. The most specific marker for identifying a small percentage of hairy cells in peripheral blood cytospins, was t-GP. In alkaline phosphatase/anti alkaline phosphatase (APAAP) stained preparations, t-GP+ hairy cells (provided with large cytoplasm and hairy surface) could be usually distinguished from t-GP+ normal lymphocytes (small-sized cells with smooth surface). In doubtful cases the percentage of residual hairy cells could exactly be estimated by double immunofluorescence staining for CD22 (B-cell marker) and t-GP. The rationale of the test is based on the finding that the small percentage (about 1%) of t-GP+ lymphocytes circulating in the peripheral blood of normal individuals are T-cells of the CD8 subset and not B-cells. The best markers for identifying residual hairy cells in routine bone marrow biopsies were CD45RA (mAb 4KB5) and CD20 (mAb L26). Immunohistological labelling was superior to morphological examination in picking up scattered hairy cells in bone marrow biopsies showing either severe hypoplasia or exuberant hyperplasia of normal haemopoietic series.

Reticulin fibre content of bone marrow infiltrates of malignant non-Hodgkin's lymphomas (B-cell type, low malignancy)--a morphometric evaluation before and after therapy

A morphometric study was performed on bone marrow infiltrates of non-Hodgkin's lymphomas (B-cell type, low malignancy) to evaluate the content of argyrophilic (reticulin) fibres in the various subtypes before and after therapy. In congruence with the corresponding lymph node lesions, subtypes consisted of lymphocytic lymphoma--chronic lymphocytic leukaemia (CLL, n = 39), centroblastic-centrocytic lymphoma (CB-CC, n = 35), lymphoplasmacytoid immunocytoma (LPI, n = 22) and finally hairy cell leukaemia (HCL, n = 21). In comparison with control specimens, morphometric measurements on trephine biopsies (initial staging procedure) disclosed a borderline or minimal increase in reticulin in CLL and moderate fibrosis in CB-CC and LPI, whereas HCL had the greatest increase in fibres. The marrow surrounding focal or patchy lymphoma infiltrates of CLL and CB-CC displayed no relevant changes in fibre density with respect to the control samples. Following chemotherapy, repeated trephine biopsies (restaging procedure) were obtainable from 38 patients. There was no significant decrease in the fibre content of CLL, CB-CC and LPI infiltrates. In HCL an incomplete reduction was recorded after interferon treatment. So-called benign lymphoid lesions may be distinguished from focal-patchy infiltrates of CB-CC and LPI not only by showing a central localization, but also by the absence of significant amounts of reticulin. However, considering the density of the reticulin fibres, a clear-cut discrimination of these lymphoid aggregates from an early nodal-central growth pattern of CLL is not feasible in many cases.

Reduced hematologic response to alpha-interferon therapy in patients with hairy cell leukemia showing a peculiar immunologic phenotype

Alpha-interferon (alpha-IFN) treatment is highly effective in normalizing the clinical, hematologic, and immunologic parameters of patients with hairy cell leukemia (HCL). Complete remissions (CR), however, are rare, and a few patients do not respond adequately to alpha-IFN. That the poor response to alpha-IFN treatment could be related to a particular immunologic surface marker profile of the HC was investigated in this study. The results showed that most patients who do not respond adequately to alpha-IFN HC have a peculiar immunologic phenotype with a positive response to the Leu1 (CD5) monoclonal antibody, usually absent on HC but characteristically expressed on B-chronic lymphocytic leukemia cells. Of nine HCL patients with this phenotype, only three had partial remissions (PR) and six minor responses (MR) compared with the three CR, 16 PR, and three MR observed in the 22 Leu1 (CD5)-negative patients. The authors postulate that a more extensive immunologic analysis of HCL patients at diagnosis may be predictive of the response to IFN treatment.

Immunoglobulin DNA Analysis as a Marker of Clonality in the Follow-up of Patients with Hairy Cell Leukemia Treated with Alpha-Interferon

In fourteen patients with hairy cell leukemia (HCL) the configuration of the immunoglobulin (Ig) heavy chain genes was used as a marker of clonality, to monitor the response of the neoplastic population to treatment with alpha-interferon (a-IFN). In agreement with the morphological, hematological and immunological data, twelve of them showed, after a variable length of therapy, a complete disappearance of rearranged bands in peripheral blood cells. In one patient, who was treated less intensively, the molecularly-defined neoplastic population was still present on two consecutive determinations, whilst in the last patient persistence of disease was repeatedly documented despite prolonged A-IFN treatment. Three further cases were analyzed sequentially: in two, no rearranged bands could be found at repeated determinations; the third, who was in complete remission whilst on 3 × 10(6) U of α-IFN every other day, showed recurrence of disease nine months later when on a maintenance protocol with 3 × 10(6) U/weekly. Nine bone marrow specimens were also analyzed following treatment with α-IFN. In four a monoclonally rearranged band could still be detected, while in another four, reversal of fibrosis and hemopoietic recovery wits coupled with the absence of a molecularly recognizable neoplastic clone. In the last (case, persistence of disease paralleled the findings in the peripheral blood cells. These data indicate that α-IFPJ is capable of producing a specific cytolytic effect on the leukemic population in HCL, which in some cases may lead to complete clonal remissions. Analysis at the DNA level may represent a valuable tool towards monitoring the clinical course of HCL patients and for optimal individual therapeutic scheduling.

The inhibitory effect of serum from hairy-cell leukaemia patients on normal progenitor cells may disappear following prolonged treatment with alpha-interferon

The possibility that serum from hairy-cell leukaemia (HCL) patients at diagnosis may show an inhibitory effect on the in vitro colony growth of normal haemopoietic progenitor cells has been suggested. Several studies have documented the efficacy of alpha-Interferon (alpha-IFN) in inducing a complete restoration of peripheral blood values and, in some cases, a complete clinical remission. In this study we have evaluated the regulatory effect of serum, collected before and after 3 and 12 months of alpha-IFN treatment, from 10 patients with untreated HCL, on the in vitro growth of normal bone marrow CFU-GM, BFU-E and CFU-MK. The effect of conditioned media, prepared from enriched hairy cells (HC) cultured in synthetic medium, on the growth of normal haemopoietic progenitors was also investigated. The results obtained confirm that sera from untreated HCL patients display a variable degree of inhibitory activity in the progenitor cell compartments analysed. Disappearance of the inhibitory activity, particularly evident for the erythroid compartment, was found only in patients who displayed a disappearance of circulating HC and a good haematological response after prolonged (12 months) treatment with alpha-IFN. The possibility that the serum of patients with HCL may contain a haemopoietic inhibitory factor, released by the neoplastic HC population, is suggested.