Optimal sequencing of ibrutinib, idelalisib, and venetoclax in chronic lymphocytic leukemia: results from a multicenter study of 683 patients

Background

Ibrutinib, idelalisib, and venetoclax are approved for treating CLL patients in the United States. However, there is no guidance as to their optimal sequence.

Patients and methods

We conducted a multicenter, retrospective analysis of CLL patients treated with kinase inhibitors (KIs) or venetoclax. We examined demographics, discontinuation reasons, overall response rates (ORR), survival, and post-KI salvage strategies. Primary endpoint was progression-free survival (PFS).

Results

A total of 683 patients were identified. Baseline characteristics were similar in the ibrutinib and idelalisib groups. ORR to ibrutinib and idelalisib as first KI was 69% and 81%, respectively. With a median follow-up of 17 months (range 1-60), median PFS and OS for the entire cohort were 35 months and not reached. Patients treated with ibrutinib (versus idelalisib) as first KI had a significantly better PFS in all settings; front-line [hazard ratios (HR) 2.8, CI 1.3-6.3, P = 0.01], relapsed-refractory (HR 2.8, CI 1.9-4.1, P < 0.001), del17p (HR 2.0, CI 1.2-3.4, P = 0.008), and complex karyotype (HR 2.5, CI 1.2-5.2, P = 0.02). At the time of initial KI failure, use of an alternate KI or venetoclax had a superior PFS when compared with chemoimmunotherapy. Furthermore, patients who discontinued ibrutinib due to progression or toxicity had marginally improved outcomes if they received venetoclax (ORR 79%) versus idelalisib (ORR 46%) (PFS HR .6, CI.3-1.0, P = 0.06).

Conclusions

In the largest real-world experience of novel agents in CLL, ibrutinib appears superior to idelalisib as first KI. Furthermore, in the setting of KI failure, alternate KI or venetoclax therapy appear superior to chemoimmunotherapy combinations. The use of venetoclax upon ibrutinib failure might be superior to idelalisib. These data support the need for trials testing sequencing strategies to optimize treatment algorithms.

Peripheral T-cell lymphomas in a large US multicenter cohort: prognostication in the modern era including impact of frontline therapy

BACKGROUND

Optimal frontline therapy for peripheral T-cell lymphoma (PTCL) in the modern era remains unclear.

PATIENTS AND METHODS

We examined patient characteristics, treatment, and outcomes among 341 newly diagnosed PTCL patients from 2000 to 2011. Outcome was compared with a matched cohort of diffuse large B-cell lymphoma (DLBCL) patients, and prognostic factors were assessed using univariate and multivariate analyses.

RESULTS

PTCL subtypes included PTCL, not otherwise specified (PTCL-NOS) (31%), anaplastic large T-cell lymphoma (ALCL) (26%), angioimmunoblastic T-cell lymphoma (23%), NK/T-cell lymphoma (7%), acute T-cell leukemia/lymphoma (6%), and other (7%). Median age was 62 years (range 18-95 years), and 74% had stage III-IV disease. Twenty-three (7%) patients received only palliative care whereas 318 received chemotherapy: CHOP-like regimens (70%), hyperCVAD/MA (6%), or other (18%). Thirty-three patients (10%) underwent stem-cell transplantation (SCT) in first remission. The overall response rate was 73% (61% complete); 24% had primary refractory disease. With 39-month median follow-up, 3-year progression-free survival (PFS) and overall survival (OS) were 32% and 52%. PFS and OS for PTCL patients were significantly inferior to matched patients with DLBCL. On multivariate analysis, stage I-II disease was the only significant pretreatment prognostic factor [PFS: hazard ratio (HR) 0.54, 95% confidence interval (CI) 0.34-0.85, P = 0.007; OS: HR 0.42, 95% CI 0.22-0.78, P = 0.006]. ALK positivity in ALCL was prognostic on univariate analysis, but lost significance on multivariate analysis. The most dominant prognostic factor was response to initial therapy (complete response versus other), including adjustment for stage and SCT [PFS: HR 0.19, 95% CI 0.14-0.28, P < 0.0001; OS: HR 0.26, 95% CI 0.17-0.40, P < 0.0001]. No overall survival difference was observed based on choice of upfront regimen or SCT in first remission.

CONCLUSIONS

This analysis identifies early-stage disease and initial treatment response as dominant prognostic factors in PTCL. No clear benefit was observed for patients undergoing consolidative SCT. Novel therapeutic approaches for PTCL are critically needed.

A multicenter phase II study incorporating high-dose rituximab and liposomal doxorubicin into the CODOX-M/IVAC regimen for untreated Burkitt's lymphoma

BACKGROUND

Despite improvement with intensive multi-agent chemotherapy, 2-year progression-free survival (PFS) rates for adults with high-risk Burkitt's lymphoma (BL) remains <55%.

PATIENTS AND METHODS

We conducted a phase II trial for newly diagnosed classic BL utilizing liposomal doxorubicin (Adriamycin) in lieu of doxorubicin and incorporating intravenous rituximab (at 500 mg/m(2) twice/cycle) into the CODOX-M/IVAC regimen. Correlative analyses included paired serum and cerebrospinal fluid (CSF) rituximab levels and close examination of cardiac function.

RESULTS

Among 25 BL patients, the median age was 44 years (23-70) and 4 patients were HIV positive. There were 20 high-risk and 5 low-risk patients. At baseline, 40% of high-risk patients had bone marrow involvement, 35% had bulky disease and 15% had central nervous system involvement. The overall response rate was 100% (complete remission 92%). At 34-month median follow-up, the 2-year PFS and overall survival (OS) rates for all patients were 80% and 84%, respectively (low-risk: both 100%; high-risk: 76% and 81%, respectively). Furthermore, the 2-year PFS, OS, and disease-specific survival (DSS) rates for high-risk, HIV-negative patients were 84%, 89% and 100%, respectively. Adverse events (AEs) appeared to be consistent with prior CODOX-M/IVAC data, although there were several grade 3 cardiac events noted (all declined ejection fraction without clinical symptoms). The mean serum rituximab levels at 24 h after cycles 1 and 3 for patients without relapse were 258 and 306 μg/ml, respectively, versus 131 and 193 μg/ml, respectively, for patients with early progression (P = 0.002 and 0.002, respectively). The mean CSF rituximab levels for all patients were 0.11 and 0.24 μg/ml, respectively, at cycle 1 (24/72 h), which equated to serum:CSF ratios of 0.05% and 0.20%, respectively.

CONCLUSIONS

The integration of rituximab into CODOX-M/IVAC for adult BL was feasible and tolerable, while changes in cardiac function warrant continued examination. This regimen was associated with excellent survival rates for HIV-negative BL. Further investigation of the predictive value of serum rituximab is needed. Clinicaltrials.gov NCT00392990.

A phase II study evaluating the toxicity and efficacy of single-agent temsirolimus in chemotherapy-naïve castration-resistant prostate cancer

BACKGROUND

The mammalian target of rapamycin (mTOR) pathway is deregulated in castration-resistant prostate cancer (CRPC). We investigated the efficacy and toxicity of temsirolimus, an mTOR inhibitor, in chemotherapy-naïve CRPC.

METHODS

In this phase II open label study, eligible patients received IV temsirolimus at 25 mg weekly until objective disease progression, unacceptable toxicity or investigator's discretion. Toxicity was assessed every 4 weeks and responses every 8 weeks. Primary end point was calculating the overall response (OR) rate as well as measuring stable disease (SD) to assess the overall clinical benefit calculated as OR+SD. Secondary end points included prostatic-specific antigen (PSA) changes and time to progression biochemically and radiographically. Correlative studies included prospective assessment of quality of life (QoL) using two previously validated scales.

RESULTS

Although the sponsor halted the study early, 21 patients were enrolled of which, 15 were evaluable for efficacy and OR. Median age was 74 (range: 57-89), median PSA was 237.5 ng ml(-1) (range: 8.2-2360), visceral disease present in 11 patients (52%), and 17 patients (81%) patients had Gleason score (7-10). Two patients had a partial response (PR) and eight had SD. The OR was 13% (2/15) and the overall clinical benefit (OR+SD) was 67% (10/15). Median time to radiographic disease progression was 2 months (range 2-10 months). Biochemical response assessment was available for 14/15 patients. Any PSA decline was observed in four patients (28.5%; 4/14) with one patient (7%) having >50% PSA decline. Median time to progression by PSA was 2 months (range 1-10 months). With a median follow-up of 32 months, median overall survival (OS) was 13 months (range: 2-37) and three patients remain alive at the data cutoff (5/2013) for an OS of 14% at 4 years on an intent-to-treat analysis. Major non-haematologic toxicities included fatigue (19%) and pneumonia (14%). Main laboratory toxicities included hyperglycaemia (24%) and hypophosphatemia (14%). Also, 52% of enrolled patients had serious adverse events. Other toxicities were consistent with previously reported adverse events with temsirolimus. Despite these observed adverse events, temsirolimus did not adversely impact QoL.

CONCLUSION

Temsirolimus monotherapy has minimal activity in chemotherapy-naïve CRPC.

Examination of the follicular lymphoma international prognostic index (FLIPI) in the National LymphoCare study (NLCS): a prospective US patient cohort treated predominantly in community practices

BACKGROUND

Because follicular lymphoma (FL) patients have heterogeneous outcomes, the FL international prognostic index (FLIPI) was developed to risk-stratify patients and to predict survival. However, limited data exist regarding the role of FLIPI in the era of routine first-line rituximab (R) and R-chemotherapy regimens and in the setting of community oncology practices.

PATIENTS AND METHODS

We evaluated the outcome data from the National LymphoCare Study (NLCS), a prospective, observational cohort study, which collects data on patients with FL in the United States (US) community practices.

RESULTS

Among 1068 male and 1124 female patients with FLIPI data, most were treated in US community practices (79%); 35% were FLIPI good risk, 30% intermediate risk, and 35% poor risk. FLIPI risk groups were significant predictors of overall survival (OS) and progression-free survival (PFS) for patients who undergo watchful waiting (WW), and those who receive non-R-containing regimens, R-alone, and R-chemotherapy combinations.

CONCLUSIONS

In the setting of contemporary practice with routine R use, stratifying patients into good, intermediate, and poor FLIPI risk groups predicts distinct outcomes in terms of OS and PFS. FLIPI remains an important prognostic index in the R era and should be used in clinical practices to support discussions about prognosis.

Phase I study investigating the safety and feasibility of combining imatinib mesylate (Gleevec) with sorafenib in patients with refractory castration-resistant prostate cancer

Background:

Determining the maximum tolerated dose (MTD) and the dose-limiting toxicity (DLT) of sorafenib (S) plus imatinib (IM) in castration-resistant prostate cancer (CRPC) patients.

Methods:

Refractory CRPC patients were enrolled onto this 3+3 dose escalation designed study. Imatinib pharmacokinetics (PK) were determined on day 15, 4 h post dose with a validated LC–MS assay.

Results:

Seventeen patients were enrolled; 10 evaluable (6 at 400 mg S qd with 300 mg IM qd (DL0) and 4 at 400 mg S bid with 300 mg IM qd (DL1)); inevaluable patients received <1 cycle. The median age was 73 (57–89); median prostatic serum antigen was 284 ng ml⁻¹ (11.7–9027). Median number of prior non-hormonal therapies was 3 (1–12). Dose-limiting toxicities were diarrhoea and hand-foot syndrome. Maximum tolerated dose was 400 mg S and 300 mg IM both daily. No biochemical responses were observed. Two patients had stable disease by RECIST. Median time to progression was 2 months (1–5). Median OS was 6 months (1–30+) with 3/17 patients (17%) alive at 21 months median follow-up. Ten patients had PK data suggesting that S reduced IM clearance by 55%, resulting in 77% increased exposure (P=0.005; compared with historical data).

Conclusion:

This is the first report showing that S+IM can be administered in CRPC at a dose of 400 mg S and 300 mg IM, daily.

Subsequent treatment with APC8015F and its effect on survival in the control arm of phase III sipuleucel-t studies

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Background: Sipuleucel-T is an autologous cellular immunotherapy approved for metastatic castrate resistant prostate cancer.

Methods: After disease progression, subjects in the control arms of 3 randomized controlled sipuleucel-T trials were offered 3 infusions of APC8015F, an autologous immunotherapy made from cells cryopreserved at the time of control generation.

Results: Of 249 control subjects, 165 (66.3%) received APC8015F; the median time from randomization to first infusion was 5.2 months (range 1.8 to 33.1), median time from objective disease progression to first APC8015F infusion was 2.2 months (range 0.5 to 14.6), and 145 subjects (87.9%) received all 3 infusions. The frequency of infusional toxicities was increased following APC8015F relative to control infusion, but was slightly lower than following sipuleucel-T. APC8015F-treated subjects (n=155) had improved post-progression survival relative to untreated controls (n=61) (HR=0.52 [95%CI 0.37, 0.73] p=0.0001, log rank test, unadjusted Cox regression); however, APC8015F-treated subjects had more favorable prognostic features than untreated controls. A Cox regression analysis adjusting for baseline PSA and LDH demonstrated that APC8015F therapy remained a predictor of survival in control subjects (HR=0.56 [95%CI 0.40, 0.80]; p=0.001). A Cox regression model adjusting for age, PSA, LDH and post-randomization docetaxel use (yes/no), also showed a significant effect for salvage treatment among control subjects (HR=0.55 [95%CI 0.39, 0.78] p<0.001). Examination of APC8015F product characteristics demonstrated that cumulative CD54 upregulation was associated with survival following first infusion in subjects who progressed and received APC8015F (p=0.03), consistent with previous reports of correlations between sipuleucel-T product parameters and overall survival.

Conclusions: Although confounded with measured and unmeasured factors influencing outcome, these analyses suggest that post-progression treatment with APC8015F may have extended the survival of subjects in the control arms of these studies.

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Novel approaches and future directions in castration-resistant prostate cancer

Recent advances in the treatment of castration-resistant prostate cancer (CRPC) have started to change the therapeutic landscape allowing clinicians to choose from a broad range of treatment options. Understanding the mechanisms that transform prostate cancer (PCA) into a castration-resistant state has enabled investigators to explore critical pathways involved in such process allowing for rational therapeutic design. These novel therapies complement the modest success that chemotherapy has demonstrated in recent years. In this review, we discuss the different mechanisms that render PCA castration resistant and elaborate on the nonchemotherapy approaches evolving in CRPC. These include agents targeting the epidermal growth factor receptor, endothelin receptor antagonists, angiogenesis inhibitors, immunomodulatory agents, immunotherapy, novel antiandrogens, and delivery of cytotoxic agents via therapeutic antibodies. This timely review coincides with the identification of newer therapies in this setting affirming our steady movement towards better disease control.

Docetaxel and oxaliplatin as first-line therapy for advanced non-small cell lung cancer: a phase II trial

We sought to evaluate the safety and efficacy of docetaxel and oxaliplatin combination as first-line therapy for patients with stage IV or wet III(B )non small cell lung cancer. Patients received oxaliplatin at 85 mg/m(2) intravenously over 2 hours on days 1 and 15 along with docetaxel at 30 mg/m(2) intravenously on days 1 and 8; both given every 28 days. Cycles were repeated every 4 weeks for a maximum of 6. Fifteen patients were enrolled for an overall response rate of 50% (95% CI 21-74%). Median progression-free survival was 2.4 months with a 1-year progression free survival of 10%. Median overall survival was 7.9 months with 49% of patients alive at 1 year. Most common toxicities were nausea, vomiting, and dehydration. This combination has notable activity in advanced non-small cell lung cancer with a favorable toxicity profile.

Maintenance GM-CSF in patients with castration-resistant prostate cancer (CRPC) who maximized their response to chemotherapy

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Background: There is no standard treatment for CRPC patients (pts) who completed chemotherapy. Time to progression (TTP) ranges from 3–6 months after stopping chemotherapy. GM-CSF (GM) is an immune-based growth factor with reported activity in CRPC. We hypothesized that GM maintenance in pts who have maximized their response to chemotherapy could delay TTP or time to next treatment (TNT). Methods: Eligible pts were those with CRPC who completed 10–12 cycles of docetaxel (D) or mitoxantrone (M) chemotherapy without progression; or those who maximized their response to chemotherapy before completing 10–12 cycles. Maximum response was defined as a <10% change in PSA repeated on two occasions with stable disease (SD) radiographically. Enrolled pts received GM at 250 ug/m2 subcutaneously for 14 days followed by 14-days of rest. GM was continued until disease progression. Primary end point was the clinical benefit defined as the sum of partial response (PR), complete response (CR) and SD. Secondary end points included toxicity, TTP, and TNT. Results: To date, 12 pts out of planned 20 have been enrolled (9 were on D and 3 on M). Median age was 78 (66–96). Median PSA at enrollment was 56.5 (0.1–566). Only 1 pt had a Gleason score < 7. Median time from initial diagnosis to GM was 70 months. Median number of chemotherapy cycles prior to GM was 9 (6–12). Eight pts (66%) had visceral and bone disease. GM was well-tolerated with no drug-related grade 3 and/or 4 toxicities. Ten pts are evaluable (1 pt withdrew consent and another did not comply). Median GM cycles received so far was 3 (2–11). With a median follow up of 11 months (2–17), 3 pts demonstrated SD and 2 had PR for an overall clinical benefit of 50%. One pt remains on study at 7 months while the median response duration for the other 4 responding pts was 7 months. Four pts never received another treatment but the median TNT in other evaluable pts was 3 months. Conclusions: GM is safe, well tolerated, and has activity in CRPC after stopping chemotherapy. Combining chemotherapy with GM should be investigated in future studies.

[Table: see text]

Effect of sorafenib on chemotherapy resistance and refractoriness in castration-resistant prostate cancer (CRPC)

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Background: There is no standard for CRPC once chemotherapy fails. In studies employing docetaxel (D), 35–39% of pts did not complete therapy due to progression and only 45–50% had a PSA response. This implies that many pts develop resistance to D. Sorafenib is a multi kinase inhibitor with antiangiogenesis properties. We hypothesized that sorafenib could overcome chemotherapy resistance in these pts. Methods: Eligible pts must have progressed while on either D or mitoxantrone (M). They received sorafenib at 400 mg orally twice/daily in addition to the chemotherapy agent they were on. Sorefinib/chemotherapy combination was given for a maximum of 6 cycles followed by sorafenib monotherapy until progression. Primary end point was safety of the sorafenib/chemotherapy combination. Secondary end points included the overall clinical benefit calculated as the sum of complete response (CR), partial response (PR), and stable disease (SD), toxicity, and time to disease progression (TTP). Results: To date, 15 pts have been enrolled; 14 are evaluable. Eleven pts were on D and 4 on M. Median age was 68 (range 61–83), median PSA was 111.2 ng/ml (13.6–1703.9). Nine pts (60%) had visceral and bone disease. Median PSA-DT pre-study was 2 months (0.5–6) and median time from last chemotherapy to starting study was 4 weeks. Median number of given cycles was 6.5 (2–12). Six pts did not require dose reduction, 2 others were re-escalated to the full dose. Sorafenib was safely combined with chemotherapy with 6 pts experiencing grade 3 fatigue, 3 developing grade 3 hand/foot syndrome, and 1 experiening grade 3 diarrhea. Eleven pts (73%) had SD radiographically that lasted a median of 6.7 months. In all, 6 out of 14 pts (42%) had a PSA decline after adding sorafenib and 3 (21%) had stable PSA. Of these 9 pts (PR+SD), 2 never doubled their PSA. Two pts had PSA decline after withdrawing sorafenib. Median TTP for PSA was 3.75 months. PSA responses did not correlate with radiographic changes or clinical benefit. With a median follow-up of 8 months, 5 pts (33%) remain alive with 1 continuing on therapy without progression. Conclusions: Sorafenib overcomes chemotherapy-refractoriness and failures in CRPC.

[Table: see text]

Erlotinib has activity in androgen-independent prostate cancer (AIPC) patients who are chemotherapy-naive: A phase II trial

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Background: Mechanisms of hormone resistance for AIPC are variable. One proposed mechanism is the over expression of the epidermal growth factor receptor (EGFR) which in turn stimulates proliferation through its pathway. We aimed to determine the efficacy of an oral anti-EGFR inhibitor (erlotinib) in this patient population that was chemotherapy-naive. The primary end point was to evaluate the overall clinical benefit defined as the sum of complete response (CR), partial response (PR), and stable disease (SD). Methods: Between January and December 2006, sixteen patients were enrolled onto this phase II study. Median age was 78 years (66–85). Median PSA was 61.9 (9.2–800.2). Median time from initial diagnosis until starting Erlotinib was 7.8 years. Erlotinib was given daily at 150 mg until disease progression. Patients were evaluated every 2 weeks for toxicity. Response assessment took place every 2 cycles (each cycle was 4 weeks). Evaluations included computed tomography of measurable disease areas, bone scans, and serum PSAs. Patients who progressed radiographically but maintained a PSA response or those who progressed biochemically but maintained a radiographic response were considered stable and were allowed to continue on study. Results: Sixteen patients were enrolled with 14 being evaluable at this time (2 patients are early in their course). Median cycles received is 2 (range 1.5–12). One patient achieved a PR and continues on Erlotinib after one year of enrollment. Three patients demonstrated stable disease but two of them later progressed. One patient withdrew after 9 days of starting therapy due to fatigue and poor taste. All other patients developed disease progression after two cycles of therapy. The calculated overall clinical benefit was 28% (4 responses out of 14 patients). One patient died from pneumonia and seizures unrelated to Erlotinib as confirmed by an autopsy that showed progression in the central nervous system. Erlotinib was well-tolerated with skin rash and diarrhea being the most common toxicities. Conclusions: Erlotinib has clinical activity as a single agent in AIPC. Updated results of this ongoing study will be presented at the meeting. Further studies with this agent alone or in combination are warranted.

No significant financial relationships to disclose.

Gemtuzumab ozogamicin (MylotargTM) is infrequently associated with sinusoidal obstructive syndrome/veno-occlusive disease

BACKGROUND

Gemtuzumab ozogamicin (GO) is approved for the treatment of older adults with acute myeloid leukemia in first relapse. Several reports have suggested an association between GO administration and hepatic veno-occlusive disease (VOD), which has recently been termed sinusoidal obstructive syndrome (SOS). However, the majority of these studies were done in patients who had undergone high-dose therapy with stem cell transplantation or when GO was administered in combination with other cytotoxic chemotherapy.

PATIENTS AND METHODS

We performed a retrospective review of all patients treated at our institution with single-agent GO, either as initial therapy or in the relapsed and refractory setting. All patients were planned to receive GO 9 mg/m2 in two doses, 14 days apart. We reviewed liver function tests before and after administration and analyzed hepatic injuries in the context of patients' other comorbid conditions. Patients were classified as experiencing liver toxicity if their liver function(s) abnormality lasted for > 7 days, as documented by repeated serum studies.

RESULTS

Forty-seven patients were analyzed. Response rate (27.2%) and median duration of response (6 months) were comparable to other reports. All patients were assessable for liver toxicity, of which 23 (48%) had elevation of at least one of their liver function tests (alanine aminotransferase, aspartate aminotransferase, total bilirubin or alkaline phosphatase). Elevations in liver function test(s) were noted at a median of 14 days (range 7-175 days). Eight patients had other comorbid conditions that could explain their liver abnormality, making the incidence of direct GO-induced liver injury 31%. However, only one patient had radiographic and clinical evidence suggesting SOSVOD.

CONCLUSIONS

When administered using the recommended dose and schedule, GO has little association with VODSOS if given as a single agent. In this retrospective review, the incidence of GO-related SOSVOD is as low as 2%.

Secondary acute myelogenous leukemia with MLL gene rearrangement following radioimmunotherapy (RAIT) for non-Hodgkin's lymphoma

Targeted therapy with conjugated and unconjugated monoclonal antibodies for non-Hodgkin's lymphoma has revolutionized the approach to this disease. The efficacy and low toxicity of these agents have allowed introduction of this strategy in the early stages of therapy. Longer follow-up is needed before validating the safety of these agents. Since monoclonal antibodies are being given as front-line therapy, it is important to identify all potential adverse events. We report a case of secondary acute myelogenous leukemia (AML) with 11q23 cytogenetic abnormality and mixed lymphoid leukemia (MLL) gene expression in a patient treated with Y90 labeled anti-CD20 antibody (Zevalin). The patient was not exposed to topoisomerase II inhibitors. Our observations suggest a relationship between 11q23 leukemia and radioimmunotherapy (RAIT) and further studies are needed.

Gemcitabine in hematologic malignancies

Gemcitabine is a pyrimidine analogue that showed significant activity in solid malignancies. Gemcitabine acts by inhibiting DNA synthesis through chain termination and ribonucleotide reductase inhibition. During initial phase I and II studies, gemcitabine had a low toxicity profile and was well tolerated as a single agent and in combination therapy. Recently, there has been more interest in studying the activity of gemcitabine in hematologic malignancies. Gemcitabine demonstrated good activity in refractory Hodgkin disease patients, non-Hodgkin lymphoma, cutaneous T-cell lymphoma, and acute leukemias. There is a preponderance of evidence on the activity of gemcitabine in vitro in myeloma and leukemic cell lines. The activity of gemcitabine in these disorders will pave the way for incorporating this agent into the early phases of therapy.

The role of bone marrow transplantation in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is characterized by a specific gene rearrangement and the generation of the PML-RARalpha fusion transcript which results from a translocation between chromosomes 15 and 17. Targeted therapy with all-trans retinoic acid (ATRA) and anthracycline-based chemotherapy results in an apparent cure in 70-80% of patients. Both allogeneic (ALLO) and autologous (AUTO) hematopoietic stem cell transplantation (HSCT) are effective in acute myeloid leukemia (AML), but their role in APL is not clear given the excellent outcome with ATRA and chemotherapy. Several retrospective studies have analyzed the outcome of patients undergoing AUTO or ALLO-HSCT in first (CR1) or second (CR2) complete remission. Most of these studies have shown significant transplant-related mortality (TRM) with ALLO-HSCT, but a reduction in relapse rate compared with AUTO-HSCT. The high TRM with ALLO-HSCT and the excellent outcome with ATRA and chemotherapy do not justify recommending this procedure for the majority of patients in CR1. The role of AUTO-HSCT in CR1 also is unclear. A small subset of patients at high risk of relapse, possibly identifiable by a high white blood cell count at presentation may benefit from HSCT. Most patients with relapsed disease achieve CR2 with ATRA, arsenic trioxide, or combination therapy. However, it is not known if these responses are sustained or if consolidation with HSCT has a place in this setting. The outcome of AUTO-HSCT in CR2 using stem cells that are negative for PML-RARalpha is excellent. It is unclear whether ALLO-HSCT from an HLA-identical sibling is superior to AUTO-HSCT with PML-RARalpha-negative cells in CR2 since the former would be associated with graft-versus-leukemia effects and the latter with lower TRM. Alternatively, arsenic trioxide or re-treatment with ATRA, followed by intensive chemotherapy may also be effective. A randomized prospective clinical trial, or a retrospective analysis of the available data would be useful in answering this critical question.

The alternatively spliced type II corticotropin-releasing factor receptor, stably expressed in LLCPK-1 cells, is not well coupled to the G protein(s)

Two alternatively spliced corticotropin-releasing factor receptor (CRF-R) cDNAs, type I and type II, were recently isolated from a human cDNA library. The two cDNAs are identical except that the type II cDNA encodes an additional 29 amino acid inserted in the first putative cytoplasmic loop. Since the first cytoplasmic loop is highly conserved in all the members of the hCRF receptor family we have examined whether the presence of the 29 amino acid cassette in CRF-RII influences G protein coupling in LLCPK-1 cells stably expressing the type I and type II hCRF receptors. Whether measured in intact cells or in membrane preparations, LLCPK-1 cells stably expressing CRF-RII have a 4-5 fold lower binding affinity. Maximal CRF-stimulated cAMP accumulation in LLCPK-1 cells stably expressing CRF-RI was 10-15-fold higher than that in LLCPK-1 cells expressing CRF-RII. The EC50 for CRF-stimulated cAMP accumulation in hCRF-RI-expressing cells was in the range of 0.5 +/- 0.2 nM. In contrast, the EC50 for CRF-stimulated cAMP accumulation in hCRF-RII expressing cells was 7.7 +/- 0.2 nM. hCRF increased phosphoinositide turnover in LLCPK-1 cells stably expressing CRF-RI but not in those expressing CRF-RII; this effect required hCRF concentrations of 100 nM and higher. In membrane preparations, GTP-gamma-S inhibited hCRF binding to CRF-RI and shifted the binding Kd from 4.5 nM to 16.7 nM. Conversely, GTP-gamma-S did not influence hCRF binding to CRF-RII in broken cell membranes. Additionally, CRF-stimulated adenylate cyclase activity in cell membranes expressing CRF-RI was potentiated by GTP, whereas CRF-stimulated adenylate cyclase activity in cell membranes expressing CRF-RII was insensitive to GTP. These data indicate that CRF-RII is not well coupled to the G protein. Since the only difference between the CRF-RII and CRF-RI is the insert in the first putative cytoplasmic loop, these data indicate that the first cytoplasmic loop plays a crucial role in hCRF receptor coupling to the G protein.