Treatment of relapsing acute promyelocytic leukemia by all-trans retinoic acid therapy followed by timed sequential chemotherapy and stem cell transplantation. APL Study Group. Acute promyelocytic leukemia.

The purpose of this study was to assess the safety and efficacy of stem cell transplantation (SCT) mainly autologous SCT as consolidation therapy in APL patients who relapsed and achieved a second complete remission (CR2). Fifty adult patients with a first relapsed APL, of whom 39 had been previously treated with ATRA, entered a multicenter trial of oral ATRA until complete remission (CR) achievement followed by timed sequential chemotherapy (EMA combining etoposide 200 mg/m2/day for 3 days, mitoxantrone 12 mg/m2/day for 3 days, and cytarabine 500 mg/m2/day for two sequences of 3 days). EMA was started either after CR achievement, or on day 1 of ATRA because of initial white blood cell (WBC) counts >5 x 10(9)/l, or rapidly added to ATRA in order to prevent ATRA syndrome because WBC count increased under ATRA. Forty-five patients (90%, 95% CI 78%-97%) were in CR after induction therapy. Five patients died from infection during aplasia following EMA chemotherapy. Eleven patients who achieved CR had a familial HLA-identical donor and were allografted. The median disease-free survival (DFS) of allografted patients was 8.2 months. The 34 other CR patients were scheduled for autologous peripheral blood (PB) SCT (intent-to-treat group). Actually, autologous transplantation was only carried out in 22 patients (65%) (17 PBSCT and five autologous bone marrow transplantation (BMT)). Reasons for not autografting were early relapse (three patients), severe toxicity of EMA chemotherapy (six patients), and refusal or failure of stem cell harvest (three patients). The 3-year DFS rate of patients actually autografted was 77%. Among the 17 autografted patients still in CR2, nine patients have already reached a longer CR2 than first CR (CR1). Results of detection of PML/RARalpha by RT-PCR after autologous transplantation show negative findings in eight of the nine patients tested. We conclude that (1) ATRA combined to EMA chemotherapy is effective in the treatment of relapsed APL; (2) allogeneic BMT may be too toxic after salvage treatment including EMA intensive chemotherapy; (3) clinical outcome of autografted patients and preliminary molecular results regarding detection of PML/RARalpha after autologous PBSCT are encouraging.     

Analysis of prognostic factors in newly diagnosed patients with acute promyelocytic leukemia: the APL92 study of the Japan Adult Leukemia Study Group (JALSG)

All-trans-retinoic acid (ATRA) has been incorporated in front-line therapy for newly diagnosed acute promyelocytic leukemia (APL). We conducted a multicenter study of differentiation therapy with ATRA alone or in combination with chemotherapy followed by intensive postremission chemotherapy in patients with APL (the JALSG APL92 study), and analyzed prognostic factors to increase the cure rate in our subsequent trial. From 1992 to 1997, adult patients with newly diagnosed APL received oral ATRA 45 mg/m2 daily alone until complete remission (CR) if initial leukocyte counts were < 3.0x10(9)/l, and ATRA daily plus daunorubicin (DNR) 40 mg/m2x3 days plus enocitabine (BHAC) 200 mg/m2x5 days if leukocyte counts were > or =3.0 x 10(9)/l. If peripheral blasts exceeded 1.0x10(9)/l during therapy, DNRx3 days plus BHACx5 days was added. After CR was achieved, three courses of consolidation and six courses of maintenance/intensification chemotherapy were administered. Of 376 patients enrolled, 369 were evaluable (median age 46 years, range 15-86 years; median leukocyte counts 2.0x10(9)/l), and 333 (90%) achieved CR (94% of patients treated with ATRA alone, 88% with ATRA plus later chemotherapy, 89% with ATRA plus initial chemotherapy, and 86% with ATRA plus initial and later chemotherapy). At a median follow-up of 45 months, the predicted 6-year overall and event-free survival (EFS) rates for all patients were 65% and 52%, respectively. Favorable prognostic factors for CR were younger age, no or mild purpura, high serum total protein level, low lactate dehydrogenase level, and no or mild disseminated intravascular coagulation (DIC). Favorable prognostic factors for EFS were leukocyte counts < 10.0x10(9)/l, mild DIC, and no sepsis during induction therapy. In the JALSG APL97 study, we intensified chemotherapy for patients with leukocyte counts > or =3.0x10(9)/l, and are randomly testing whether further chemotherapy is required for APL patients with negative PCR for PML/retinoic acid receptor alpha in the maintenance phase.     

Outcome of childhood acute promyelocytic leukemia with all-trans-retinoic acid and chemotherapy.

PURPOSE: To determine the results of treatment combining all-trans-retinoic acid (ATRA) and chemotherapy (CT) in childhood acute promyelocytic leukemia (APL). PATIENTS AND METHODS: Children (< 18 years) with newly diagnosed APL were included in the APL93 trial, treated by ATRA followed or combined with daunorubicin-cytarabine, and then randomly assigned between no maintenance, intermittent ATRA, continuous CT, or both. RESULTS: Of the 576 patients included in APL93 trial, 31 (5%) were children, including 22 girls (71%) and nine boys (29%). Thirty of the children (97%) obtained complete remission (CR). ATRA syndrome occurred in four children (13%), who all achieved CR, and headaches occurred in 12 children (39%), with signs of pseudotumor cerebri in five children (16%). Seven patients (23%) relapsed. None of the eight patients who received both ATRA and CT for maintenance relapsed. All relapsing patients achieved a second CR. Twenty-two patients remained in first CR after 43+ to 96+ months, six remained in second CR after 17+ to 66+ months, and three patients had died. The 5-year event-free survival (EFS), relapse, and overall survival rates were 71%, 27%, and 90%, respectively. No difference between adults and children included in the APL93 trial was seen for CR rate, 5-year relapse rate, EFS, and overall survival, but significantly better survival was seen in children after adjustment on WBC counts (P =.02) and incidence of microgranular M3 variant (P =.04). CONCLUSION: ATRA combined with CT for induction and also probably for maintenance provides as favorable results in children with APL as in adults and currently constitutes the reference first-line treatment in both age groups.     

All trans retinoic acid in acute promyelocytic leukemia.

All trans retinoic acid (ATRA) is able to induce complete remission (CR) in almost all patients with acute promyelocytic leukemia (APL) through in vivo differentiation of APL blasts. However, it cannot eliminate the leukemic clone and to be effective must be used in combination with anthracycline-based chemotherapy. Experience accumulated over the last 10 years has clearly shown that the combination of ATRA and chemotherapy gives better survival in newly diagnosed APL than chemotherapy alone because of fewer relapses and a higher CR rate experienced by these patients. It is also strongly suggested that maintenance treatment with ATRA, and possibly in combination with low-dose chemotherapy, can further reduce the incidence of relapse. Overall, more than 90% of patients with newly diagnosed APL can achieve CR and about 75% can be cured by the combination of ATRA and chemotherapy.     

Upfront maintenance therapy with arsenic trioxide in acute promyelocytic leukemia provides no benefit for non‐t(15;17) subtype

Aims: The optimal maintenance therapy for patients with acute promyelocytic leukemia (APL) who achieved complete remission (CR) and complete consolidation chemotherapy is still controversial. Whether the use of arsenic trioxide (ATO) alone or along with all‐trans retinoic acid (ATRA) improves overall survival (OS) or disease‐free survival (DFS) is still debated. Methods: A retrospective reivew was conducted of 20 patients diagnosed with APL according to the French – American – British system. After achieving CR and receiving consolidation chemotherapy, nine patients were given maintenance therapy for 1 year (ATRA 45 mg/m²/day p.o., mercaptopurine 60 mg/m²/day p.o. and ATO 0.15 mg/kg/day × 5 days/week for six cycles in five patients; ATRA 45 mg/m²/d p.o. alternating with ATO 0.15 mg/kg/day × 5 days/week in 1 patient; ATRA only in three patients). Results: In all patients the rates of CR, 3‐year OS and 5‐year OS were 75, 71 and 57%, respectively. For patients treated with ATO maintenance, the rates were 100% for both 5‐year OS and 5‐year DFS. Four of six patients on ATO maintenance had grade 1 or grade 2 adverse events. Excluding the two patients who died from intracerebral hemorrhage within 4 days after diagnosis, these rates were 85, 82 and 78%, respectively. Conclusion: Upfront ATO maintenance therapy for one year is safe and appears to be effective, with the benefits restricted to patients with APL with t(15;17) translocation. Larger studies will be required to confirm this observation.     

Combination therapy with arsenic trioxide, all-trans retinoic acid, and gemtuzumab ozogamicin in recurrent acute promyelocytic leukemia

BACKGROUND: From 20% to 30% of patients with acute promyelocytic leukemia (APL) who are treated with all-trans retinoic acid (ATRA) develop recurrent disease. Arsenic trioxide (ATO) is an effective agent for the salvage of patients with recurrent APL, and gemtuzumab ozogamicin (GO) has shown activity in patients with APL. METHODS: The authors investigated the efficacy of a combination of ATO, ATRA, and GO in 8 patients with APL in first recurrence (7 patients with hematologic recurrences and 1 patient with a molecular recurrence). All patients had received previous treatment with ATRA either alone or in combination with other agents. Patients received ATO 0.15 mg/kg intravenously until they achieved a bone marrow complete remission (CR). Once in CR, patients received consolidation with ATO, ATRA, and GO for 10 months. Patients then received maintenance with idarubicin, ATRA, 6-marcaptopurine, and oral methotrexate for 11 months. RESULTS: All 7 patients who had hematologic recurrences achieved CR after a median of 39 days (range, 21-56 days). After a median follow-up of >/=36 months (range, 4-55 months), 6 patients remained alive in CR, and 2 patients died in CR. Six of 8 patients remained in second CR that was longer than their first CR. All 7 evaluable patients achieved molecular remission. There were no grade 3 or 4 extramedullary toxicities. Two patients died, 1 secondary to a complication of metastatic lung adenocarcinoma, and the other of sepsis. CONCLUSIONS: The combination of ATO, ATRA, and GO was effective and may achieve durable remissions in patients with APL in first recurrence. It should be considered as an effective alternative to allogeneic or autologous transplantation.     

Effect of all-trans-retinoic acid alone or in combination with chemotherapy in newly diagnosed acute promyelocytic leukaemia

Between February 1992 and November 1996 we treated 30 newly diagnosed acute promyelocytic leukaemia (APL) patients either with oral all-trans-retinoic acid (ATRA) alone (45 mg m^-2) or with a simultaneous combination of ATRA (45 mg m^-2), daunorubicin (DNR, 50 mg/m^-2 for 3 days) and cytosine arabinoside (ARA-C, 200 mg m^-2 for 7 days). There were 15 patients in each group. Patients with a white blood cell count < 5 x 10⁹/l at diagnosis received only ATRA as an induction therapy. Patients with initial white blood cell count > 5 x 10⁹/l received a combination of ATRA, DNR and ARA-C as an induction therapy. Within the first 20 days of induction, there were two early deaths in the group of patients receiving only ATRA, and six early deaths in the group of patients treated with a combination of ATRA and chemotherapy. Ten out of 13 patients (76.9%) receiving ATRA only achieved complete remission (CR) whereas seven out of nine patients (77.8%) receiving ATRA with chemotherapy achieved CR. Initial median peripheral white blood cell counts were significantly lower in the group of patients treated with ATRA alone (2.3 x 10⁹/l) than in the group of patients receiving ATRA and chemotherapy (14.0 x 10⁹/l). Morphological evidence of differentiation was noted in all patients entering CR. Patients in both groups who achieved CR received one course of standard ′3+7′ chemotherapy (DNR 45 mg m^-2,1 -3 days, ARA-C 200 mg m^-2,1-7 days) followed by two courses of standard ′2+5′ chemotherapy (DNR 50 mg m^-2 1-2 days, ARA-C 200 mg m^-2 1-5 days) as a consolidation therapy. Patients not achieving remission (three out of 13 in the ATRA group and two out of nine in ATRA+chemotherapy group) did not respond to salvage chemotherapy and all died within 3 months of diagnosis. Only one out of 10 patients (10%) in CR, treated with ATRA is in relapse after 18 months. In patients treated with ATRA alone two out of 10 (20%) survived 58 months following diagnosis whereas in the ATRA+chemotherapy group one out of seven has already survived their 58th month since diagnosis. Four out of eight patients with an early death died of retinoic acid syndrome. Other toxicities due to ATRA were minimal (cheilitis, xerosis, dermatitis, diarrhoea, liver damage or pseudotumor cerebri).     

Treatment of Newly Diagnosed Acute Promyelocytic Leukemia (APL) by All Transretinoic Acid (ATRA) Combined with Chemotherapy: The European Experience

All transretinoic acid (ATRA) gives complete remission (CR) rates of 80 to 90% in newly diagnosed acute promyelocytic leukemia (APL). However, it has two major drawbracks (1) a rapid rise in WBC in some patients, with potentially fatal ATRA syndrome (2) rapid relapse with maintenance therapy using ATRA alone or low dose chemotherapy. The French APL group therefore designed a treatment approach with ATRA followed by intensive chemotherapy. The latter was administered after CR achievement with ATRA, or was rapidly added to ATRA in case of rapid rise in leukocyte counts. This combined approach, in a pilot study and in a randomized trial, proved superior to intensive chemotherapy alone, by slightly increasing the CR rate but more importantly by reducing the relapse rate. These results were confirmed by the Chinese, Japanese and New York groups. Our group (and other European groups) are now testing in a new randomized trial the better timing of ATRA and chemotherapy administration (ATRA followed by chemotherapy or ATRA plus chemotherapy) and the role (after an intensive consolidation) of maintenance treatment with intermittent ATRA, continuous low dose chemotherapy or both.     

Thrombosis in patients with acute promyelocytic leukemia treated with and without all-trans retinoic acid

Laboratory evidence of disseminated intravascular coagulation (DIC) and/or fibrinolysis is present in the majority of patients with acute promyelocytic leukemia (APL). Historically, early hemorrhagic death (EHD) occured in 10% to 30% of patients treated with chemotherapy. All-trans retinoic acid (ATRA), a differentiating agent, has a CR rate above 80% in patients, with ATRA-associated leukocytosis. We studied thrombotic events in this population and compared it to patients treated with chemotherapy alone. The results of studies using ATRA in patients with APL were reviewed. Patients received ATRA 45-50 mg/m² orally in two divided doses daily until complete remission. In newly diagnosed patients, Idarubicin 12 mg/m²/day was given intravenously for 4 to 5 days beginning on the fifth day of ATRA therapy or when the white blood cell count (WBC) was over 10×10³/μl. Thrombotic complications were noted in 3 of 31 patients during induction. Two died from thrombotic events during therapy with multiple thromboses documented at autopsy. ATRA syndrome was suspected in 2 of the patients with thromboses and only 1 of the patients without thrombosis. In previous studies, 1 of 25 APL patients treated with chemotherapy alone had thrombotic events during therapy. In conclusion, treatment of APL with ATRA may decrease the incidence of hemorrhagic complications, but does not eliminate thrombosis. While thrombotic events were not significantly increased in patients treated with ATRA, they were more common in patients suspected of having ATRA syndrome.     

全反式维甲酸联合化疗治疗小儿急性早幼粒细胞白血病

目的观察全反式维甲酸（ATRA）联合化疗治疗小儿急性早幼粒细胞白血病（APL）的疗效。方法22例初治患儿用ATRA诱导治疗;当患儿获完全缓解（CR）后,给予DA方案或IDA方案或HA方案或AA方案巩固治疗3个疗程;以后再用ATRA、化疗交替巩固治疗36个月。结果2例在诱导治疗前死于弥散性血管内凝血（DIC）、颅内出血;22例获CR,CR率100％（20／20）。1、3、5年无病生存（DFS）率分别为100％（20／20）、93．3％（14／15）、84．7％（11／13）。ATRA常见毒副作用依次为皮肤和口唇干燥、头痛、恶心、呕吐、肝功能损害及维甲酸综合征。结论ATRA联合化疗治疗小儿APLCR率高、远期疗效好;在诱导治疗前,DIC、颅内出血仍是APL患儿死亡的主要原因;ATRA毒副作用可耐受。     

Long-term follow-up confirms the benefit of all-trans retinoic acid in acute promyelocytic leukemia. European APL group.

First results of a randomized trial (APL91 trial) and other randomized or non-randomized studies have shown that ATRA followed by chemotherapy significantly increased event-free survival (EFS) and survival, and decreased the incidence of relapse by comparison to chemotherapy alone in newly diagnosed APL. We present here long-term follow-up of the APL91 trial. In this trial, 101 patients had been randomized between ATRA followed by three courses of daunorubicin-AraC chemotherapy (ATRA group) and the same chemotherapy alone (chemotherapy group). Results were reanalyzed 73 months after closing of patient entry. Updated results of APL 91 trial found a Kaplan-Meier estimate of EFS and relapse rate at 4 years of 63% and 31% in the ATRA group, as compared to 17% and 78% in the chemotherapy group (P= 10(-4) and relative risk 2.95, P= 10(-4) and relative risk 3.68, respectively). Kaplan-Meier survival at 4 years was 76% in the ATRA group and 49% in the chemotherapy group (P= 0.026, relative risk 2.7). In the chemotherapy group, seven of the 27 relapses occurred after 18 months, but no relapse was seen after 43 months. In the ATRA group, four of the 17 relapses occurred after 18 months, including two late relapses (at 58 and 74 months). In the chemotherapy group, 23 of the 25 patients who relapsed achieved a second CR with ATRA, and the Kaplan-Meier estimate of second relapse was 40% at 30 months. In the ATRA group, the 10 patients who relapsed and were retreated with ATRA achieved a second CR. In conclusion, long-term results of APL91 trial confirm the superiority of the combination of ATRA and chemotherapy over chemotherapy alone in newly diagnosed APL, and that ATRA should be incorporated in the front-line treatment of APL.     

三氧化二砷联合全反式维甲酸治疗初发急性早幼粒细胞白血病50例疗效观察

 目的　观察三氧化二砷（ATO）联合全反式维甲酸（ATRA）治疗初发急性早幼粒细胞白血病（APL）的疗效。方法　98例初发APL患者分为对照组和治疗组,对照组48例,治疗组50例。对照组采用常规ATRA+DA双诱导方案治疗;治疗组采用ATRA每天25 mg／m2,ATO每天0.15 mg／kg（ATRA后第10天开始）联合治疗,直至完全缓解（CR）,CR后接受ATO和ATRA联合巩固治疗。比较两组CR率、PML-RARα融合基因转阴时间及5年无病生存率。结果　对照组和治疗组CR率分别为89.5 %（43／48）和90.0 %（45／50）,获得CR时间分别为（30.0±5.1）d和（28.1±4.4）d,两组CR率（χ2＝-0.068,P＝0.946）及获得CR时间（t＝1.757,P＝0.083）相比差异均无统计学意义。在所有获得CR的患者中,3例分别在CR后第276、385和394天复发。所有患者发病时PML-RARα融合基因均阳性,对照组和治疗组CR时分别有25.0 %（5／20）和29.4 %（5／17）转阴,巩固后分别有92.5 %（37／40）和97.6 %（41／42）转阴。对照组和治疗组5年无病生存率分别为（85.3±5.9）%和（87.6±5.6）%,差异无统计学意义（χ2＝0.232,P＝0.630）。结论　ATO联合ATRA能有效治疗初发APL患者,可以作为常规化疗方案外的另一选择。     

Treatment of acute promyelocytic leukemia: strategy toward further increase of cure rate.

Acute promyelocytic leukemia (APL) has become a curable disease by all-trans retinoic acid (ATRA)-based induction therapy followed by two or three courses of consolidation chemotherapy. Currently around 90% of newly diagnosed patients with APL achieve complete remission (CR) and over 70% of patients are curable. To further increase the CR and cure rates, detection and diagnosis of this disease at its early stage is very important, hopefully before the appearance of APL-associated coagulopathy. In induction therapy, concomitant chemotherapy is indispensable, except for patients with low initial leukocyte counts. Prophylactic use of intrathecal methotrexate and cytarabine should be done, particularly for patients with hyperleukocytosis. If patients relapse hematologically or even molecularly, arsenic trioxide will be the treatment of choice under careful electrocardiogram monitoring. Am80, liposomal ATRA, gemtuzumab ozogamicin or ATRA in combination with cytotoxic drugs may be used at this stage or later. Allogeneic SCT will be the treatment of choice after patients of age <50 years have relapsed, provided that they have HLA-identical family donors or DNA-identical unrelated donors.     

以亚砷酸为主方案治疗急性早幼粒细胞白血病的分子生物学疗效

 目的　观察以亚砷酸为主的方案治疗初治的急性早幼粒细胞白血病（APL）的细胞学及分子生物学疗效。方法　56例APL患者均经骨髓细胞形态学检查、组织化学检查、免疫表型测定以及FISH法和实时定量PCR法检测PML／RARα融合基因而确诊。诱导化疗方案采用亚砷酸10 mg／d,静脉滴注,直至获得完全缓解。缓解后采用亚砷酸与化疗交替治疗,以亚砷酸为主。对20例患者的PML／RARα融合基因进行动态观察。结果　56例PML-RARα融合基因阳性的初治APL患者完全缓解率98.2 ％,CR中位时间32（23～42） d。实时定量RT-PCR检测阳性的32例患者中位随访期3年,总生存率100 ％,复发率3.12 ％。完全缓解24个月后分子生物学缓解率100 ％（6／6）。结论　以亚砷酸为主的方案治疗PML／RARα融合基因阳性的APL患者疗效好,血液学缓解后24个月有可能获得分子生物学缓解。     

Clinical experience with a new synthetic retinoid, tamibarotene (Am-80) for relapsed or refractory acute promyelocytic leukemia

A new synthetic retinoid, Am-80 is expected to overcome all-trans retinoic acid (ATRA) resistance, because of several times more potent differentiation activity than ATRA and sustained plasma level during continuous administration due to a lower affinity for cellular retinoic acid binding protein. In a preliminary study in Japan, 14 (58%) of 24 acute promyelocytic leukemia (APL) patients who had relapsed from ATRA induced complete remission (CR) achieved a second CR. Of these 14 CR patients, 4 of 6 who underwent allogeneic stem cell transplantation (SCT) are alive, and 4 of 8 patients who received only chemotherapy are alive without relapse for >4 years. Adverse events include xerosis, cheilitis, hyperlipidemia and so on, but these were generally milder than ATRA. In a phase 2 clinical trial, 25 (61%) of 41 patients entered CR. Among 23 first relapsed patients, 18 (78.3%) patients entered CR, indicating excellent salvage effects for ATRA-relapsed patients. Am-80 may improve disease free survival when used as remission induction and/or maintenance therapy, and it may be effective for relapse from ATRA-induced remission and be curative for patients who receive SCT or intensive post remission chemotherapy.     

三氧化二砷治疗初治急性早幼粒细胞白血病疗效分析

 目的　分析以三氧化二砷（ATO）为基础的诱导和维持治疗方案治疗初发急性早幼粒细胞白血病（APL）的长期疗效。方法　回顾性分析62例初诊成年APL患者诱导缓解治疗和缓解后巩固维持治疗经过,并作5、7年随访分析。结果　诱导治疗阶段,ATO+全反式维甲酸（ATRA）双药联合化疗组与ATRA联合化疗组完全缓解（CR）率差异无统计学意义,但前者达到CR时间明显缩短。诱导治疗后PML-RARα融合基因转阴率两组分别为86.2 %、56.3 %,差异有统计学意义（P＜0.05）。巩固维持治疗阶段,ATO序贯维持组和化疗序贯维持组5年总生存（OS）率分别为（94.4±5.4）%和（45.5±10.2）%,7年OS率分别为（52.5±23.7）%和（27.3±9.3）%;两组5年无病生存（DFS）率分别为（94.7±5.5）%和（41.3±10.1）%,7年DFS率分别为（52.6±23.7）%和（27.5±9.4）%,两组差异有统计学意义（P＜0.05）。并且,ATO序贯维持组复发率（14.7 %）低于化疗序贯维持组（37.0 %）,差异有统计学意义（P＜0.05）。结论　以ATO联合ATRA、化疗的诱导化疗方案可缩短诱导化疗时间,提高PML-RARα融合基因转阴率,而且,包含ATO的序贯维持治疗明显改善APL患者的长期生存,减少复发,安全性高,患者耐受性好。     

Single-agent liposomal all-trans retinoic acid can cure some patients with untreated acute promyelocytic leukemia: an update of The University of Texas M. D. Anderson Cancer Center Series

The present study aimed to investigate single-agent liposomal all-trans retinoic acid (Lipo-ATRA) in untreated acute promyelocytic leukemia (APL). Induction therapy consisted of Lipo-ATRA 90 mg/m2 i.v. every other day. Patients in complete remission (CR) continued to receive Lipo-ATRA 90 mg/m2 i.v. three times a week for 9 months. Idarubicin was added only if a polymerase chain reaction test for promyelocytic leukemia-retinoic acid receptor alpha (sensitivity level, 10(-4)), performed every 3 months from CR, was positive. The results were compared with those of a historical control group treated with oral ATRA and idarubicin. Lipo-ATRA induced CR in 79% of patients; CR rates were 92% and 38% in patients with white blood cell (WBC) counts <10 x 10(9)/L and >10 x 10(9)/L, respectively. Ten of the 26 responders to Lipo-ATRA remain in first CR at a median of 6.4 years, despite never receiving idarubicin; all 10 had initial WBC counts <10 x 10(9)/L. The 5-year survival rate was 76% for patients treated with Lipo-ATRA. Comparisons with oral ATRA+idarubicin as given at M. D. Anderson are confounded because of their historical nature and the absence of ATRA from post-remission therapy in the former group. Nonetheless, a multivariate Cox model identified higher WBC counts and older age, but not treatment (historical vs. Lipo-ATRA), as being predictive of shorter relapse-free and overall survival. Lipo-ATRA can cure patients presenting with WBC counts <10 x 10(9)/L (low risk) without additional therapy, contrary to conventional ATRA, which, when given alone, probably cures no patients. The observation that patients can be cured of APL without the use of chemotherapy should encourage further study of 'targeted' therapy in APL and in other leukemias.     

Pre-Treatment with All-Trans Retinoic Acid Accelerates Polymorphonuclear Recovery After Chemotherapy in Patients with Acute Promyelocytic Leukemia

All-trans retinoic acid (ATRA) is currently being used as remission induction treatment for acute promyelocytic leukemia (APL). Conventional chemotherapy is added both during and after ATRA treatment, in order to avoid the occurrence of hyperleukocytosis, and to improve the duration of complete remission. In this study we analysed the hematopoietic recovery of 18 consecutive APL patients after standard Idarubicin or Daunorubicin ± Cytosine-Arabinoside regimens. 9 of the patients were at the onset of the disease, (CHT group) while 9 had been pre-treated with ATRA 45 mg/sqm/day for at least 3 months (ATRA group). 500 PMN/mmc were reached after 20.8 day from the end of treatment in CHT group and after 12.0 days in ATRA group (p = 0.007). Platelets recovery was faster, even though not significantly, in ATRA group. Interestingly, PMN recovery in ATRA group was even shorter (p = 0.004) than that obtained in CHT group, after the first course of chemotherapy (treatment in CR vs treatment in CR). If these results are confirmed in a larger study, a protective effect of ATRA on normal residual hemopoiesis should be postulated.