Timing of exercise therapy when initiating adjuvant chemotherapy for breast cancer: a randomized trial.

AIMS: The most appropriate timing of exercise therapy to improve cardiorespiratory fitness (CRF) among patients initiating chemotherapy is not known. The effects of exercise therapy administered during, following, or during and following chemotherapy were examined in patients with breast cancer. METHODS AND RESULTS: Using a parallel-group randomized trial design, 158 inactive women with breast cancer initiating (neo)adjuvant chemotherapy were allocated to receive (1:1 ratio): usual care or one of three exercise regimens-concurrent (during chemotherapy only), sequential (after chemotherapy only), or concurrent and sequential (continuous) (n = 39/40 per group). Exercise consisted of treadmill walking three sessions/week, 20-50 min at 55%-100% of peak oxygen consumption (VO2peak) for ≈16 (concurrent, sequential) or ≈32 (continuous) consecutive weeks. VO2peak was evaluated at baseline (pre-treatment), immediately post-chemotherapy, and ≈16 weeks after chemotherapy. In intention-to-treat analysis, there was no difference in the primary endpoint of VO2peak change between concurrent exercise and usual care during chemotherapy vs. VO2peak change between sequential exercise and usual care after chemotherapy [overall difference, -0.88 mL O2·kg-1·min-1; 95% confidence interval (CI): -3.36, 1.59, P = 0.48]. In secondary analysis, continuous exercise, approximately equal to twice the length of the other regimens, was well-tolerated and the only strategy associated with significant improvements in VO2peak from baseline to post-intervention (1.74 mL O2·kg-1·min-1, P < 0.001). CONCLUSION: There was no statistical difference in CRF improvement between concurrent vs. sequential exercise therapy relative to usual care in women with primary breast cancer. The promising tolerability and CRF benefit of ≈32 weeks of continuous exercise therapy warrant further evaluation in larger trials.

A phase 1 study evaluating the combination of an allosteric AKT inhibitor (MK-2206) and trastuzumab in patients with HER2-positive solid tumors.

INTRODUCTION: Trastuzumab is effective in human epidermal growth factor receptor 2 (HER2)-over-expressing breast and gastric cancers. However, patients may develop resistance through downstream signaling via the phosphatidylinositol 3-kinase (PI3K)/AKT pathway. This phase 1 trial was conducted to determine the safety and tolerability of the investigational AKT inhibitor MK-2206, to prepare for future studies to determine whether the combination with trastuzumab could inhibit compensatory signaling. METHODS: Patients with HER2+ treatment-refractory breast and gastroesophageal cancer were enrolled. Treatment consisted of standard doses of intravenous trastuzumab and escalating dose levels of oral MK-2206 using either an every-other-day (45 mg and 60 mg QOD) or once-weekly (135 mg and 200 mg QW) schedule. RESULTS: A total of 34 patients with HER2+ disease were enrolled; 31 received study-drug. The maximum tolerated dose (MTD) for MK-2206 in combination with trastuzumab was 60 mg for the QOD schedule and 135 mg for the QW schedule, although a true MTD was not established due to early termination of the trial. The most common treatment-emergent toxicities included fatigue, hyperglycemia, and dermatologic rash, consistent with prior experience; one death unrelated to treatment was reported. There was one complete response in a patient with metastatic breast cancer, one patient achieved a partial response, and 5 patients had stable disease for at least 4 months, despite progression on multiple prior trastuzumab- and lapatinib-based therapies. Results also indicate that trastuzumab does not affect the pharmacokinetics of MK-2206. CONCLUSIONS: Results suggest the AKT inhibitor MK-2206 can be safely combined with trastuzumab, and is associated with clinical activity, supporting further investigation. TRIAL REGISTRATION: ClinicalTrials.gov; identifier: NCT00963547.

Phase II trial of a novel capecitabine dosing schedule in combination with lapatinib for the treatment of patients with HER2-positive metastatic breast cancer.

Our group applied mathematical modeling to capecitabine dosing and predicted 7 days of treatment followed by 7 days of rest (7-7) would improve efficacy and minimize toxicity. The conventional schedule of capecitabine limits full dosing in combination with other agents due to toxicity. Lapatinib inhibits the tyrosine kinase of HER2 and has activity when added to conventionally scheduled capecitabine for the treatment of patients with trastuzumab-refractory, HER2-positive, metastatic breast cancer (MBC). We performed this study to evaluate the activity and tolerability of capecitabine 7-7 with lapatinib in patients with trastuzumab-refractory MBC. Eligible patients had measurable, HER2-positive, MBC that progressed following exposure to trastuzumab. Treatment consisted of capecitabine 2,000 mg orally twice daily, 7-7 and lapatinib 1,250 mg orally daily. The primary endpoint was response rate. Secondary endpoints included toxicity, progression-free survival, and stable disease ≥ 6 months. Twenty-three patients were treated on study. More than 60% had prior chemotherapy for MBC and all had prior trastuzumab. After a median of 23 weeks (range 2-96+), five patients had partial responses (23; 95 CI, 7-44%) and six (27; 95 CI, 10-48%) had stable disease ≥ 6 months. Median progression-free survival was 9.4 months. The most common treatment-related toxicities ≥ grade (gr) 2 were hand-foot syndrome (gr 2 43%; gr 3 4% gr 4 0%), diarrhea (gr 2 26%; gr 3/4 0%), elevated liver chemistries (gr 2 17%; gr 3/4 0%), and anemia (gr 2 13%; gr 3 4%; gr 4 4%). No grade ≥ 3 nausea, vomiting, or diarrhea events occurred. This study demonstrated feasibility and after meeting biostatistical requirements for continued accrual was terminated in anticipation of slow enrollment. Capecitabine 7-7 with lapatinib was well tolerated with minimal gastrointestinal toxicity. Antitumor activity was observed in patients with trastuzumab-refractory MBC.

Phase 2 trial of a novel capecitabine dosing schedule in combination with bevacizumab for patients with metastatic breast cancer.

BACKGROUND: Capecitabine has antitumor activity in metastatic breast cancer (MBC); however, its optimal dose and schedule remain unclear. Mathematical modeling predicts that a capecitabine schedule 7 days of treatment followed by 7 days of rest (7-7) will improve efficacy and minimize toxicity. Bevacizumab has demonstrated the ability to improve outcomes when it is added to chemotherapy, including capecitabine, in the first-line and second-line settings. METHODS: Patients with measurable MBC received oral capecitabine (2000 mg twice daily; 7-7), and intravenous bevacizumab (10 mg/kg every 2 weeks). The primary endpoint was the response rate. Secondary endpoints included toxicity, the clinical benefit rate, and progression-free survival (PFS). RESULTS: Forty-one patients were treated. After a median of 7 cycles (range, 1-32 cycles), partial responses were observed in 20% of patients, and stable disease for ≥6 months was noted in 35% patients. The median PFS was 8 months. The most common treatment-related toxicities were hand-foot syndrome (49% grade 2, 20% grade 3/4) hypertension (12% grade 2, 10% grade 3/4), and fatigue (12% grade 2, 2% grade 3/4). Diarrhea (5% grade 2, 0% grade 3/4), nausea (0% grade 2-4), and vomiting (0% grade 2-4) were rare. CONCLUSIONS: Capecitabine administered for 7 days followed by a 7-day rest in combination with bevacizumab had modest efficacy and an acceptable toxicity profile in patients with MBC. Gastrointestinal toxicity with this schedule was minimal.

Assessment of Quality of Life and Treatment Outcomes of Patients With Persistent Postchemotherapy Alopecia.

Importance: Persistent alopecia occurs in a subset of patients undergoing chemotherapy, yet the quality of life (QOL) of these patients and their response to therapy have not been described in a large patient cohort. Objective: To characterize the clinical presentation of patients with persistent chemotherapy-induced alopecia (pCIA) or endocrine therapy-induced alopecia after chemotherapy (EIAC) and their QOL and treatment outcomes. Design, Setting, and Participants: A retrospective multicenter cohort of 192 women with cancer treated with cytotoxic agents who received a clinical diagnosis of persistent alopecia (98 with pCIA and 94 with EIAC) between January 1, 2009, and July 31, 2017, was analyzed. All patients were from the dermatology service in 2 comprehensive cancer centers and 1 tertiary-care hospital. Data on demographics, chemotherapy regimens, severity, clinical patterns, and response to hair-growth promoting agents were assessed. Data from the Hairdex questionnaire were used to assess the QOL of patients with alopecia. Main Outcomes and Measures: The clinical presentation, response to dermatologic therapy, and QOL of patients with pCIA were assessed and compared with those of patients with EIAC. Results: A total of 98 women with pCIA (median age, 56.5 years [range, 18-83 years]) and 94 women with EIAC (median age, 56 years [range, 29-84 years]) were included. The most common agents associated with pCIA were taxanes for 80 patients (82%); the most common agents associated with EIAC were aromatase inhibitors for 58 patients (62%). Diffuse alopecia was predominant in patients with pCIA compared with patients with EIAC (31 of 75 [41%] vs 23 of 92 [25%]; P = .04), with greater severity (Common Terminology Criteria for Adverse Events, version 4.0, grade 2) among patients with pCIA (29 of 75 [39%] vs 12 of 92 [13%]; P < .001). A negative emotional effect was reported by both groups. After treatment with topical minoxidil or spironolactone, moderate to significant improvement was observed for 36 of 54 patients with pCIA (67%) and for 32 of 42 patients with EIAC (76%). Conclusions and Relevance: Persistent chemotherapy-induced alopecia is frequently more severe and diffuse when compared with EIAC, and both groups of patients experienced a negative effect. A modest benefit was observed with dermatologic therapy. Additional studies are warranted to develop effective strategies for prevention and effective therapy for pCIA and EIAC.

Endocrine Therapy-Induced Alopecia in Patients With Breast Cancer.

Importance: Endocrine therapy-induced alopecia (EIA) has been anecdotally reported but not systematically described. Objective: To characterize EIA in patients with breast cancer. Design, Setting, and Participants: Retrospective cohort study of 112 patients with breast cancer, diagnosed with EIA from January 1, 2009, to December 31, 2016, the patients were examined at the dermatology service in a large tertiary care hospital and comprehensive cancer center. Main Outcomes and Measures: The clinical features, alopecia-related quality of life (QoL), and response to minoxidil of EIA in patients with breast cancer were assessed. Data from the Hairdex Questionnaire was used to assess the impact of the alopecia on patients QoL. Higher score indicates lower QoL (0-100 score). Efficacy of minoxidil was measured at 3 or 6 months by a single-blinded investigator through standardized clinical photographs of the scalp. Results: A total of 112 female patients with breast cancer were included (median [range] age, 60 [34-90] years). A total of 104 patients (93%) had standardized clinical photographs; of these, 59 patients (53%) had trichoscopy images available at baseline, and 46 patients (41%) were assessed for response to minoxidil. Alopecia was attributed to aromatase inhibitors in 75 patients (67%) and tamoxifen in 37 (33%). Severity was grade 1 in 96 of 104 patients (92%), and the pattern was similar to androgenetic alopecia. The predominant trichoscopic feature at baseline was the presence of vellus hairs and intermediate- and thick-diameter terminal hair shafts. A negative impact on QoL was reported, with a higher effect in the emotion domain according to the Hairdex score (mean [SD], 41.8 [21.3]; P < .001). After treatment with topical minoxidil, moderate or significant improvement in alopecia was observed in 37 of 46 patients (80%). Conclusions and Relevance: Endocrine therapies are associated with a pattern alopecia similar to androgenetic-type, consistent with the mechanism of action of causal agents. A significant negative impact on QoL was reported by patients, despite mostly mild alopecia severity.

The PARP Inhibitor Veliparib Can Be Safely Added to Bendamustine and Rituximab and Has Preliminary Evidence of Activity in B-Cell Lymphoma.

Purpose: The PARP inhibitor veliparib enhances the cytotoxicity of alkylating agents. This phase I study evaluated veliparib with the bifunctional alkylator bendamustine (VB) in patients with relapsed/refractory lymphoma, multiple myeloma, and solid malignancies, with a cohort expansion of VB with rituximab (VBR) in patients with B-cell lymphomas.Experimental Design: This dose-escalation study evaluated safety, pharmacokinetics, and preliminary efficacy of veliparib (20-400 mg twice a day, days 1-7 of 28-day cycle) and bendamustine (70 and 90 mg/m2 intravenously, days 1 and 2). A cohort expansion was conducted, which combined veliparib and bendamustine at the maximum tolerated dose (MTD) with rituximab (375 mg/m2, day 1) in patients with B-cell lymphomas. Thirty-four patients were treated in seven dose-escalation cohorts and seven patients in the dose-expansion cohort.Results: The MTD was veliparib 300 mg twice daily plus bendamustine 90 mg/m2 Dose-limiting toxicities (DLT) were anemia, nausea, hypertension, and hyperhidrosis. Grade ≥3 toxicities included lymphopenia (87.8%), anemia (19.5%), neutropenia (12.2%), thrombocytopenia (9.8%), leukopenia (9.8%), nausea (7.3%), and hypophosphatemia (7.3%). Apparent veliparib clearance was slightly lower than previously reported. Of 14 patients with lymphoma evaluable for response, five of seven (71%) on VB and six of seven (86%) on VBR achieved objective response. One patient with multiple myeloma achieved partial response.Conclusions: VB and VBR were generally well-tolerated. VBR had preliminary clinical activity in patients with B-cell lymphoma, which warrants further investigation in a phase II trial. This trial was registered at www.clinicaltrials.gov as NCT01326702 Clin Cancer Res; 23(15); 4119-26. ©2017 AACR.

Decreased gastrointestinal toxicity associated with a novel capecitabine schedule (7 days on and 7 days off): a systematic review.

Capecitabine is widely used in the management of metastatic breast cancer; however, drug delivery is limited by gastrointestinal and other toxicity. We employed mathematical modeling to rationally design an optimized dose and schedule for capecitabine of 2,000 mg twice daily, flat dosing, 7 days on, 7 days off. Preclinical data suggested increased efficacy and tolerability with this novel dosing, and three early-phase clinical trials have suggested a favorable toxicity profile. To further define the tolerability of this regimen, we conducted a systematic review of the gastrointestinal adverse events of patients on these studies. This review demonstrated a favorable gastrointestinal toxicity profile with capecitabine in this novel schedule when given as single agent or in combination therapy with either bevacizumab or lapatinib. No patients discontinued therapy for gastrointestinal toxicity, and there were no grade 4 or 5 gastrointestinal toxicities reported. Grade 3 or greater diarrhea occurred in two (2%); grade 2 or greater mucositis, constipation, and vomiting were reported in three (4%) patients. We conclude that capecitabine administered on a 7 days on, 7 days off schedule has limited gastrointestinal toxicity. Our methodology was based on an analysis of individual patient toxicity data from one phase I single-agent capecitabine and two phase II capecitabine combination studies (with bevacizumab and lapatinib, respectively), focusing specifically on gastrointestinal toxicity.

A Pilot Study of Dose-Dense Paclitaxel With Trastuzumab and Lapatinib for Node-negative HER2-Overexpressed Breast Cancer.

BACKGROUND: Dual anti-HER2 therapy is effective for HER2-amplified breast cancer. Weekly paclitaxel, trastuzumab, and full-dose lapatinib (PTL) is not feasible because of grade 3 diarrhea. We conducted a phase II feasibility study of dose-dense (DD; every other week) PTL (ClinicalTrials.gov identifier, NCT01827163). PATIENTS AND METHODS: Eligible patients had HER2-positive breast cancer, tumor size ≤ 3 cm, and negative nodes. Treatment included paclitaxel (175 mg/m(2) × 4, every 2 weeks with pegfilgrastim), trastuzumab (4 mg/kg load and then 2 mg/kg weekly), and lapatinib (1000 mg daily). After paclitaxel × 4, trastuzumab (6 mg/kg every 3 weeks) plus lapatinib were continued for 1 year. The primary endpoint was feasibility, defined as (1) > 80% of patients completing PTL without a dose delay or reduction, (2) grade 3 diarrhea rate < 20%, and (3) cardiac event rate < 4%. RESULTS: From May 2013 to November 2013, we enrolled 20 of 55 planned patients. The median age was 49 years (range, 34-74 years). One patient had immediate paclitaxel hypersensitivity and was deemed inevaluable. Only 13 of 19 evaluable patients (68%) completed PTL without a dose delay or reduction or unacceptable toxicities. Only 3 of 19 (16%) had grade 3 diarrhea. Rash was frequent, with all grades in 18 of 19 (95%) and grade 3 in 2 of 19 (11%). The study was stopped early because of excess toxicity. CONCLUSION: The discontinuation rate during DD PTL was high, owing, in part, to an unexpectedly high incidence of rash. The trial was halted, because the initial discontinuation rate from overall toxicity made it unlikely that full accrual would demonstrate feasibility.

Caspase activation is required for gemcitabine activity in multiple myeloma cell lines.

The objective of this study was to determine potential mechanisms of apoptotic activity of gemcitabine, a pyrimidine nucleoside analogue, in the MM1.S multiple myeloma (MM) cell line. A MM cell line that is sensitive to glucocorticoids (MM1.S) was used for this study. Immunoblotting analysis, cell cycle assays, and annexin V staining were performed to determine whether gemcitabine induced apoptosis in this model. Furthermore, we attempted to delineate the apoptotic pathway by measuring caspase-8 and -9 activity using fluorometric assays. Loss of mitochondrial membrane potential was measured by flow cytometry. Gemcitabine treatment caused apoptosis in MM cell lines as measured by an increase in DNA cleavage, an increase in annexin V binding, a decrease in the mitochondrial membrane potential, and activation of caspase activity. Furthermore, cleavage of the caspase substrate poly(ADP-ribose) polymerase and caspase-3 activation were documented as early as 8 h after treatment with gemcitabine. Caspase-8 and -9 were activated by gemcitabine treatment in this cell line, suggesting several mechanisms of action including death receptor pathway and mitochondrial damage. The addition of interleukin 6 to MM1.S cells treated with gemcitabine offered no protection against gemcitabine-induced cell death. Gemcitabine induced apoptosis in the MM1.S cell line, and its activity required caspase activation. There is a suggestion that mitochondrial integrity is being affected with gemcitabine in this system. Gemcitabine acts independently of interleukin 6, suggesting potential important therapeutic implications in MM patients.

Phase II study of paclitaxel given once per week along with trastuzumab and pertuzumab in patients with human epidermal growth factor receptor 2-positive metastatic breast cancer.

PURPOSE: The CLEOPATRA (Clinical Evaluation of Trastuzumab and Pertuzumab) study demonstrated superior progression-free survival (PFS) and overall survival when pertuzumab was added to trastuzumab and docetaxel. Paclitaxel given once per week is effective and less toxic than docetaxel. We performed a phase II study to evaluate the efficacy and safety of pertuzumab and trastuzumab with paclitaxel given once per week. PATIENTS AND METHODS: Patients with metastatic human epidermal growth factor receptor 2-positive breast cancer with zero to one prior therapy were enrolled. Treatment consisted of paclitaxel 80 mg/m(2) once per week plus trastuzumab (8 mg/kg loading dose → 6 mg/kg) once every 3 weeks plus pertuzumab (840 mg loading dose → 420 mg) once every 3 weeks, all given intravenously. The primary end point was 6-month PFS assessed by Kaplan-Meier methods. RESULTS: From January 2011 to December 2013, we enrolled 69 patients: 51 (74%) and 18 (26%) treated in first- and second-line metastatic settings, respectively. At a median follow-up of 21 months (range, 3 to 38 months), 6-month PFS was 86% (95% CI, 75% to 92%). The median PFS was 19.5 months (95% CI, 14 to 26 months) overall. PFS was 24.2 months (95% CI, 14 months to not reached [NR]) and 16.4 months (95% CI, 8.5 months to NR) for those without and with prior treatment, respectively. At 1 year, Kaplan-Meier PFS was 70% (95% CI, 56% to 79%) overall, 71% (95% CI, 55% to 82%) for those without prior therapy, and 66% (95% CI, 40% to 83%) for those with prior therapy. Treatment was well-tolerated; there was no febrile neutropenia or symptomatic left ventricular systolic dysfunction. CONCLUSION: Paclitaxel given once per week with trastuzumab and pertuzumab is highly active and well tolerated and seems to be an effective alternative to docetaxel-based combination therapy.

High dose cytarabine and mitoxantrone: an effective induction regimen for high-risk acute myeloid leukemia (AML).

Patients with high-risk AML, defined as those with advanced age, relapsed/refractory disease, unfavorable molecular and cytogenetic abnormalities, therapy-related myeloid neoplasm (t-MN) and multiple medical co-morbidities tend to respond poorly to standard cytarabine and daunorubicin induction therapy and have a poor prognosis. We performed a retrospective analysis of an alternative induction regimen using high dose cytarabine (HiDAC) and mitoxantrone (MITO) administered to 78 high-risk patients with AML at The University of Chicago from 2001 to 2008. The primary endpoints of the study were complete remission (CR) rate and death within 30 days of initiation of treatment. The median age was 63 years (range:23-85); 27% of these patients had a Charlson co-morbidity index (CCI) > 2. Forty-three (56%) patients had unfavorable cytogenetics, 28 (37%) had intermediate-risk cytogenetics and 5 (7%) had favorable cytogenetics. The CR rate was 45% and the CRi rate 10%; 7 patients (9%) died during induction. Notably, t-MN and relapsed/refractory patients had CR and induction death rates equivalent to de novo AML patients within this series. In this high risk AML population, HiDAC/MITO induction demonstrated an overall response rate of 55% with a low induction death rate of 9% and allowed 32 (41%) patients to proceed to allogeneic stem cell transplant.

HER2-amplified breast cancer: mechanisms of trastuzumab resistance and novel targeted therapies.

HER2 amplification is seen in up to 20% of breast cancers and is associated with an aggressive phenotype. Trastuzumab, a monoclonal antibody to HER2, accrues significant clinical benefit in the metastatic and adjuvant settings. However, some patients suffer disease recurrence despite adjuvant trastuzumab therapy, and many patients with metastatic disease do not respond to therapy or develop refractory disease within 1 year of treatment. Given the increased recognition of de novo and acquired resistance to therapy, considerable research has been dedicated to understanding the molecular mechanisms of trastuzumab resistance. Here, we highlight putative models of resistance, including activation of the downstream PI3K-signaling pathway, accumulation of a constitutively active form of HER2, and crosstalk of HER2 with other growth factor receptors. The identification of these specific mechanisms of trastuzumab resistance has provided a rationale for the development of several novel HER2-targeted agents as the mechanisms have largely suggested a continued tumor dependence on HER2 signaling. We explore the emerging data for the treatment of trastuzumab-refractory disease with novel agents including lapatinib, neratinib, pertuzumab, trastuzumab-DM1, HSP90 and PI3K pathway inhibitors, and the future potential for these inhibitors which, if combined with reliable biomarkers of resistance, may ultimately usher in a new era of personalized medicine for this disease.

Adjuvant taxanes: more to the story.

Breast cancer is a common public health problem, and the most important prognostic factors in survival or recurrence after potentially curative surgery include the number of involved axillary lymph nodes and the biology of the disease. Systemic chemotherapy remains a critical component in the eradication of occult micrometastatic disease in the adjuvant setting. The 2000 Early Breast Cancer Trialists' Collaborative Group overview of polychemotherapy in breast cancer has demonstrated that anthracycline-based regimens are superior to non-anthracycline-based therapies in terms of disease-free survival and overall survival. The taxanes paclitaxel and docetaxel were well established in metastatic breast cancer and lack cross-resistance with anthracyclines and were therefore quickly deemed worthwhile for evaluation in the adjuvant setting. A large meta-analysis showed that the addition of a taxane to an anthracycline-based regimen improves outcomes in high-risk patients regardless of age, menopausal status, number of nodes involved, hormone receptor status, and type of taxane. There are several effective anthracycline/taxane combinations traditionally studied in patients with high-risk disease. In this overview, we will review some of the key trials that have advanced the standard of care in the adjuvant setting with regard to various chemotherapy combinations.

Phase I study of the ribonucleotide reductase inhibitor 3-aminopyridine-2-carboxaldehyde-thiosemicarbazone (3-AP) in combination with high dose cytarabine in patients with advanced myeloid leukemia.

PURPOSE: This Phase I dose escalation study was based on the hypothesis that the addition of 3-aminopyridine-2-carboxaldehyde-thiosemicarbazone (3-AP) to cytarabine would enhance cytarabine cytotoxicity. The primary objective of the study was to establish the maximum tolerated dose of 3-AP when given in combination with a fixed dose of cytarabine. EXPERIMENTAL DESIGN: Twenty-five patients with relapsed or refractory myeloid leukemia were enrolled to three dose levels of 3-AP. Cytarabine was administered as a 2 h infusion at a fixed dose of 1,000 mg/m2/day for 5 consecutive days. Escalating doses of 3-AP as a 2 h infusion were administered on days 2 through 5. The 3-AP infusion preceded the start of the cytarabine infusion by 4 h. RESULTS: In general, the toxicities observed with the combination were similar to the expected toxicity profile for cytarabine when utilized as a single agent at this dose and schedule. However, two of three patients developed dose-limiting methemoglobinemia at the highest 3-AP dose studied (100 mg/m2). Transient reversible methemoglobinemia was documented in 11 of 15 patients enrolled at the 75 mg/ m2 dose level. Objective evidence of clinical activity was observed in four patients. CONCLUSIONS: The combination of 3-AP and cytarabine given on this schedule is feasible in advanced myeloid leukemia. The recommended Phase II dose is 75 mg/m2/day of 3-AP on days 2-5 given prior to cytarabine administered at a dose of 1,000 mg/m2/day over 5 consecutive days. Methemoglobinemia is a common toxicity of this combination and requires close monitoring.