Open-label, dose-escalation, safety, pharmacokinetic, and pharmacodynamic study of intravenously administered CNF1010 (17-(allylamino)-17-demethoxygeldanamycin [17-AAG]) in patients with solid tumors

BACKGROUND

17-(Allylamino)-17-demethoxygeldanamycin (17-AAG) is a benzoquinone ansamycin that binds to and inhibits the Hsp90 family of molecular chaperones leading to the proteasomal degradation of client proteins critical in malignant cell proliferation and survival. We have undertaken a Phase 1 trial of CNF1010, an oil-in-water nanoemulsion of 17-AAG.

METHODS

Patients with advanced solid tumors and adequate organ functions received CNF1010 by 1-h intravenous (IV) infusion, twice a week, 3 out of 4 weeks. Doses were escalated sequentially in single-patient (6 and 12 mg/m(2)/day) and three-to-six-patient (≥25 mg/m(2)/day) cohorts according to a modified Fibonacci's schema. Plasma pharmacokinetic (PK) profiles and biomarkers, including Hsp70 in PBMCs, HER-2 extracellular domain, and IGFBP2 in plasma, were performed.

RESULTS

Thirty-five patients were treated at doses ranging from 6 to 225 mg/m(2). A total of 10 DLTs in nine patients (2 events of fatigue, 83 and 175 mg/m(2); shock, abdominal pain, ALT increased, increased transaminases, and pain in extremity at 175 mg/m(2); extremity pain, atrial fibrillation, and metabolic encephalopathy at 225 mg/m(2)) were noted. The PK profile of 17-AAG after the first dose appeared to be linear up to 175 mg/m(2), with a dose-proportional increase in C max and AUC0-inf. Hsp70 induction in PBMCs and inhibition of serum HER-2 neu extracellular domain indicated biological effects of CNF1010 at doses >83 mg/m(2).

CONCLUSION

The maximum tolerated dose was not formally established. Hsp70 induction in PBMCs and inhibition of serum HER-2 neu extracellular domain indicated biological effects. The CNF1010 clinical program is no longer being pursued due to the toxicity profile of the drug and the development of second-generation Hsp90 molecules.

S3-5: Next Generation Sequencing Reveals Co-Activating Events in the MAPK and P13K/AKT Pathways in Metastatic Triple Negative Breast Cancers

INTRODUCTION: The clinical application of next generation sequencing to comprehensively characterize groups of driving mutations in individual metastatic triple negative breast cancer (mTNBC) genomes has the potential to reveal therapeutically relevant pathway dependencies. Towards this end, we harvested tissue from 14 patients with mTNBC and are conducting deep whole genome and transcriptome sequencing for each case to identify mutations that can guide therapeutic targeting within available phase I/II clinical trials.

METHODS: Metastatic tumor tissue was harvested from 14 mTNBC patients, and 7 samples have undergone total genome and transcriptome sequencing with the others currently underway. We are utilizing the Life Technologies SOLiD® system to sequence germline and tumor DNA to sufficient depth to identify somatic genome alterations including point mutations, indels, and structural events including translocations. Furthermore, RNA-seq is being performed on these tumors, along with a series of age- and ethnicity-matched normal breast controls to perform deep differential expression analysis, isoform expression analysis, and fusion transcript detection. Our team of genome scientists and clinical oncologists are evaluating the sequencing findings and are prioritizing the investigational therapeutic options for each patient.

RESULTS: Our whole genome and transcriptome sequencing study has revealed numerous known and novel mutations in mTNBC. However, all patients’ cancers analyzed to date had alterations that would activate the MAPK pathway, but through various mechanisms in different patients. These include BRAF amplification and overexpression, NF1 homozygous deletion, and consistent IQGAP3 overexpression. Furthermore, all patients’ cancers also harbor mutations that would activate the PI3K/AKT pathway including PTEN homozygous deletion or down-regulation, consistent INPP4B down-regulation, FBXW7 homozygous deletion, and ERAS overexpression. Moreover, although we and others show ERBB4 down-regulation in breast tumors, we are the first to report unique somatic genomic events that significantly alter the ERBB4 locus leading to its loss in the majority (5/7) of our patients’ tumors. Importantly, we are beginning to use these insights to prioritize therapeutic targeting and have observed that one chemotherapy-refractory mTNBC patient, with a high-level BRAF amplification/overexpression along with down-regulation of PTEN and INPP4B, had a major response to combined mek plus akt inhibitors on a phase I study.

CONCLUSIONS: Comprehensive genomic and transcriptomic interrogation of mTNBCs has revealed events supporting co-activation of the MAPK and PI3K/AKT pathways in all the tumors albeit by different mutational mechanisms and supports potential effectiveness of combination therapy in the treatment of mTNBC. We plan to treat these patients with combined mek plus akt inhibitors on a new phase I study beginning in August 2011 to determine the effectiveness of co-inhibition of these pathways based on this frequent genomic context.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr S3-5.

Dose-finding study of NKTR-102 in combination with cetuximab

e13503

Background: NKTR-102 is an advanced polymer conjugate of irinotecan with broad single agent activity and a unique pharmacokinetic (pk) profile. The apparent half-life of the active metabolite SN-38 in patients (pts) administered NKTR-102 is approximately 50 days. NKTR-102 in combination with cetuximab was evaluated in pts with refractory solid tumors to define the maximum tolerated dose (MTD). Methods: NKTR-102 was infused over 90 minutes every 3 weeks per cycle. Cetuximab was infused over 2 hours at 400mg/m2 on day 1 followed by a weekly 1 hour infusion at 250mg/m2. Cohorts of 3 -12 pts were treated with escalating doses of NKTR- 102. MTD was established based on the dose limiting toxicities observed in cycle 1 and safety data from subsequent cycles. Serial plasma samples were collected throughout the study for PK analysis. Results: Eighteen pts were enrolled: main tumor types include colon (5), pancreas (4), rectal (2), breast (2), gastric (1), other (4). Pts received 100 mg/m2 (12) or 125 mg/m2 (6) of NKTR-102 for a median of 2.5 cycles (range 1 to 11+). At 125 mg/m2, 3 pts had G3 diarrhea, 1 in cycle 1; 2 in cycle 2. At 100mg/m2, 1 pt had G3 diarrhea in cycle 1 and a further pt had G4 fatigue in cycle 2. Other G3 toxicities for all patients in both dose groups include nausea (3), vomiting (3) and neutropenia (2). No G3 rash was reported. Partial responses (PR) were observed in 3 pts at 100 mg/m2: confirmed (rectal, colorectal) and unconfirmed (gastric). Another pt with pancreatic cancer had a decrease in CA19–9 from 2000 at baseline to 157 U/ml with associated symptomatic benefit. NKTR-102 resulted in sustained exposure to SN-38 with no evidence of PK drug interactions between NKTR-102 and cetuximab. Conclusions: NKTR-102 shows evidence of clinical antitumor activity in combination with cetuximab. Toxicity is manageable; diarrhea and neutropenia are dose limiting. The recommended dose of NKTR-102 with cetuximab is 100mg/m2 every three weeks. Data support further evaluation of this combination in appropriate tumor types.

[Table: see text]

A phase I study of brostallicin (B) combined with either bevacizumab (BV) or irinotecan (I) in patients (pts) with advanced solid malignancies

e13531

Background: B is a DNA minor groove binding (MGB) agent with single agent cytotoxic activity. B has shown synergy with BV and I. The combinations were studied using a “complete” phase I design. Methods: The primary objective was to determine the maximally tolerated dose (MTD) and dose limiting toxicities (DLT) of B+BV and B+I. For B+BV cohort 1 both drugs were infused on day 1 of a 21 day cycle. BV was dosed at 15mg/kg, B was dosed at 6 mg/m2. For cohort 2, the BV dose was unchanged, and B dose reduced to 4 mg/m2. For B+I cohort 1 both drugs were also infused on cycle day 1. I was dosed at 200 mg/m2 with B at 4 mg/m2. For cohort 2, I was reduced to 125 mg/m2 and B reduced to 2 mg/m2. Cycle 1 DLT was defined: grade 4 neutropenia lasting ≥ 5 days, grade 3 or higher febrile neutropenia, grade 4 thrombocytopenia or grade 3 or 4 thrombocytopenia with bleeding, grade 3 or higher diarrhea, nausea or vomiting despite optimal management, grade 3 or higher for all other non-hematologic toxicities. For pts receiving BV, grade 2 or higher proteinuria. Eligible pts had treatment refractory metastatic/unresectable solid tumors, acceptable performance status, and adequate hematologic parameters and organ function. Results: 19 pts were enrolled. 11 pts received B+BV and 8 received B+I. Median age was 58 years. For B+BV 5 patients were treated in cohort 1, 6 in cohort 2. For B+I, 2 patients were treated in cohort 1, 6 in cohort 2. The MTD has not been defined for either treatment combination. In the current preliminary dataset 18/19 pts (93.3%) experienced one or more adverse events (AEs). In the B+BV group, grade 4 neutropenia was reported in 2/11 patients, both in cohort 1, and grade 3 neutropenia in one additional patient, also in cohort 1. In the B+I group, grade 4 AEs included neutropenia (DLT), febrile neutropenia (DLT), severe abdominal pain, and thrombocytopenia. Of the evaluable pts, no complete or partial responses were seen. For B+BV 5/11 pts have received 4 or more cycles, and for B+I 2/8. Conclusions: The combination of B+BV and B+I show manageable toxicity in advanced solid tumors at the doses reached in cohort 2. Additional data will be provided at the time of presentation.

[Table: see text]

Pharmacokinetic and pharmacodynamic results of a 4-hr IV administration phase I study with EPC2407, a novel vascular disrupting agent

3569

Background: EPC2407 is a 4-aryl-chromene single isomer microtubulin inhibitor with vascular disrupting and apoptotic activity at nanomolar concentrations. In an earlier phase I study dosing by 1 hr infusions daily x3 on a 21 day cycle, DLT at 21 mg/m2 was pain at tumor sites and vasoconstriction with increases of BP and QTc. MTD was 13 mg/m2 over 1 hr (ASCO 2008, Abst 2531). All drug-related toxicities resolved within an hour of stopping the infusion. Prolonged infusion of EPC2407 to extend exposure of tumor vasculature was designed with administration of EPC2407 over 4 hrs for 3 consecutive days of a 21 day cycle. Eleven patients have received this schedule and their cancers included leiomyosarcoma, colo-rectal, ovary, hepatocellular (2), NSCLC, pancreas, carcinoid, hemangiopericytoma, larynx and small bowel. Results: Doses escalated from 13 to 30 mg/m2 over 4 hours, with MTD determined to be 24 mg/m2. DLTs at 30 mg/m2 were similar to those seen in the 1 hr infusion, with pain at tumor sites in 1 participant and asymptomatic ST depression in a second. Other toxicities were also similar and included transient hypertension. QTc increases were not significant and no new toxicities were encountered. T1/2 with 4 hr infusion was ∼2hr, also seen with 1 hr infusion. AUC and Cmax values were similar to that predicted from the 1 hr data except AUC at 13 mg/m2 was lower than expected. DCE-MRI was done at baseline and after infusion on day 3, cycle 1. Analysis to date of DCE-MRI data of 4 patients showed a median decrease of 40% in both tumor permeability (Ktrans) and tumor perfusion volume (Vp). The two patients with hepatocellular carcinoma had notable stable disease and clear clinical benefit. Both patients received 18 mg/m2 dose, with one receiving 7 cycles over 5 months, and the other still on study (cycle 6) with stable disease for at least 4 cycles. Conclusions: EPC2407 shows clinical promise, with infusion-associated toxicities characteristic of the VDA drug class but without sustained or cumulative toxicity. Studies combining EPC2407 with conventional cytotoxic/cytostatic regimens are being designed.

[Table: see text]

A phase Ib/II study of PXD101 alone and in combination with 5-fluorouracil in patients with advanced solid tumors

3501

Background: PXD101 is a hydroxamate HDAC inhibitor that has broad anti-neoplastic activity in vivo and in vitro. Preclinical data showing PXD101 down-regulation of thymidylate synthase (TS), an in vivo target of 5-fluorouracil (5-FU) provide a rationale for combination of PXD101 with 5-FU. Methods: This is a phase Ib/II trial of PXD101 plus 5-FU in patients with advanced solid tumors, with dose escalation to establish the maximum tolerated dose (MTD) and an expansion at the MTD in colorectal cancer (CRC) patients. Patients (pts) must be = 18 yrs, have measurable disease, and had disease progression after standard chemotherapy. PXD101 was administered as a 30-min IV infusion on Days 1–5 of a 3-wk cycle. 5-FU was administered from cycle 2 on, as a continuous 96-hr IV infusion starting on Day 2 of the same 3-wk cycle. The primary endpoints were safety, and effect of belinostat on TS expression in patients’ tumors. Dose-limiting toxicities (DLTs) were PXD101-related = Gr 3 non-hematologic or Gr 4 hematologic toxicities. Expression of TS mRNA was measured by RTQ-PCR. Results: Twenty pts have been treated for a median of 2 cycles (range 1–8). Cohorts of 3–6 pts were tested at 5 dose levels of PXD101/5-FU (mg/m2/d): 300/250, 600/250, 1,000/250, 1,000/500, and 1,000/1,000. Two pts did not complete cycle 2, and one pt at the 600/250 dose level received 1,000 mg/m2/d 5-FU. There were no DLTs in the first 4 dose cohorts; the 5th cohort is ongoing. In the first 4 dose cohorts (17 pts), the most frequent AEs were fatigue, nausea/vomiting, dysgeusia, dehydration, constipation, edema, anorexia and anemia. There were 2 Gr 4 AEs (pulmonary embolism, bacteremia); Gr 3 AEs in = 2 pts were fatigue and dehydration. All Gr 3/4 events were assessed as not related to PXD101. One pt with stage IV CRC treated at 600/1,000 mg/m2/d PXD101/5-FU had stable disease (SD) for 8 cycles, and one pt with stage IV esophageal cancer treated at the 1,000/250 mg/m2/d dose had SD for 4 cycles. Conclusions: PXD101 in combination with 5-FU has been well tolerated up to 1,000/500 mg/m2/d PXD101/5-FU. The study is ongoing and data from the MTD expansion part, including effect of PXD101 on tumor TS expression, will be presented.

No significant financial relationships to disclose.

EPC2407, a new beta-tubulin vascular disrupting agent with potent apoptosis and cell growth inhibition

14043

Background: Compounds which bind to colchicine-like sites of microtubules have contributed greatly to the armamentarium of cancer therapies. But new modes of administration of taxanes and potent new vascular disruption agent molecules such as combretastatin continue to challenge drug development for ways to improve the therapeutic index in this important class. EPC2407 is a novel 4-aryl chromene of nM anti-tumor potency; it is crossing the translational bridge based on an array of preclinical anti-tumor pharmacology and supported by multiple toxicology trials which included drug exposure data. Methods: Vascular disrupting agents demand careful preclinical workup. What we have done is summarized in the table below. This data is from cellular metabolic, cell proliferation, vascular endothelial, in vivo tumor, and animal toxicokinetic and safety studies. Results: Please see table below of the preclinical experiments. Conclusions: A Phase I clinical trial has been designed and initiated to replicate the safety margin shown by the analysis of preclinical drug exposure data. The critical safety issue for human dosing was the dose exposure which might produce the well known ECG abnormality of delayed repolarization or prolonged QTc. A dose related QTc effect was demonstrated in cynomolgus monkeys after a 2 min infusion which achieved acute plasma exposures higher than 3836 nM. These effects were dose related and persisted only through 4 short half-lives of the parent compound. Initial human analysis fails to show any prolongation of the QTc. [JW1] [JW1]THE END HERE, all else was draft.

[Table: see text]

No significant financial relationships to disclose.

Multi-center phase II/III randomized controlled clinical trial using TNFerade combined with chemoradiation in patients with locally advanced pancreatic cancer (LAPC)

4518

Background: TNFerade is a replication-deficient adenoviral vector carrying the transgene for human TNF-a protein, regulated by the radiation-inducible promoter Egr-1. A 50 patient (pt) phase II dose-escalation study in LAPC showed a possible dose-dependent improvement in survival. To confirm these findings, the randomized Pancreatic Cancer Clinical Trial with TNFerade (PACT) study was developed. PACT is a 330 pt study, powered to detect a 20% absolute increase in the primary efficacy endpoint (overall survival at 1 year) compared to standard of care (SOC) chemoradiation. An interim analysis of safety and efficacy was planned after the first 51 pts were randomized. Survival data to 11/15/06 has been evaluated and are reported here. Methods: The TNFerade arm pts received a five- wk treatment of weekly injections of 4 x 1011 pu TNFerade, continuous infusion 5-FU (200 mg/m2/day x 5 days/wk) and 50.4 Gy radiation. TNFerade was administered by percutaneous CT-guided transabdominal injection. The SOC arm received the same regimen, without TNFerade injections. Patients were randomized 2:1 to the TNFerade and SOC arms. The first 51 randomized pts were assessed for evidence of objective response (OR) and overall survival Results: Assessment of response data is still ongoing. TNFerade + SOC was well tolerated. One year survival, the primary endpoint of the study, was 70.5% in the TNFerade + SOC arm versus 28.0% in the SOC arm, an absolute increase of 42.5%. The median survival for TNFerade + SOC pts was 515 days compared to 335 days for the SOC pts. The logrank statistic for comparison between the two arms is X2 = 2.014 (p=0.16). Conclusions: The interim survival data is preliminary. The magnitude of the difference in survival in favor of the TNFerade + SOC arm, however, is encouraging. The data appears to corroborate previous findings from the dose-escalation study, which showed an apparent survival advantage in the 4×1011 pu dose group compared to 4 x 109 pu group. A second interim analysis is planned with larger patient numbers to determine whether this early positive trend is confirmed.

No significant financial relationships to disclose.

Humanized anti-CEACAM6 PEGylated scFv: A promising novel therapy for pancreatic cancer

3042

Background: Novel Therapies for pancreatic cancer (PC) based on biological insight are urgently needed. CEACAM6, a member of the carcinoembryonic antigen (CEA) family, is a cell surface oncogene on PC cells. It is a glycoprotein composed of 3 Ig-like domains (Mr ∼35.2kD) and is linked to the plasma membrane via a glycophospholipid linked anchor. It is over-expressed on ≥95% PC patients’ found irrespective of stage of disease and represents a target for antibody therapy. Methods: Murine anti-CEACAM6 monoclonal antibody (Mab) 13–1 was humanized by a structure-based approach and single chain variable fragments (scFv) designed consisting of a Gly/Ser-linker which includes a cysteine residue for PEGylation. Murine scFv and 4 humanized scFv fragments (Version.1, 2, 7, 8) were bacterially expressed, purified, PEGylated and evaluated for activity alone or in combination with gemcitabine in human PC cell lines and mouse xenograft tumors. Cell viability, apoptosis and in-cell Westerns were done for efficacy and binding. Mouse xenograft tumors were treated with scFv or PEGylated scFv or combination with gemcitabine. Tumors (treated Vs untreated) were analyzed by immunohistochemistry for Ki-67, CD31, CEACAM6 and Caspase 3 Results: Mab 13–1, murine and 4 humanized scFvs’ were cytotoxic to CEACAM6 expressing PC cells (BxPC-3, HPAF-2) and not to PC cells that lack CEACAM6 (CaPan-2) with increased PARP-cleavage that was dose dependent (IC50=10μg/mL). Western blotting of culture media and serum from xenograft mice showed that CEACAM6 is not shed. In-cell Western confirmed humanized V.7 to be the best binder (KD=1–10μg/mL) confirming protein-protein interaction studies performed in silico with homology models of murine and humanized scFvs’ and CEACAM6. The murine scFv alone or the humanized scFV (V.8) in combination with gemcitabine delayed tumor growth by >50%. This tumor reduction correlated well with the immunohistochemical markers of response. Conclusions: We have demonstrated that CEACAM6 is a clinically relevant target in PC and that a PEGylated humanized scFv is a novel effective therapy alone and/or in combination with gemcitabine. Humanized scFv V.7 is undergoing mouse xenograft evaluation and expect will be the most effective agent to take forward into clinical development.

No significant financial relationships to disclose.

Phase I study of CNF1010 (lipid formulation of 17-(allylamino)-17-demethoxygeldanamycin: 17-AAG) in patients with advanced solid tumors

10062

Background: 17-AAG is a benzoquinone ansamycin that binds to and inhibits the HSP90 family of molecular chaperones leading to the proteasomal degradation of client proteins critical in malignant cell proliferation and survival. We have undertaken a Phase 1 trial of CNF1010, an oil-in-water nanoemulsion of 17-AAG. Methods: Patients (pts) with advanced solid tumors, ECOG PS 0–2, and adequate hematologic, hepatic, renal and cardiac functions received CNF1010 by 1 h intravenous infusion, twice-a-week, three weeks out of four, starting at 6 mg/m2 per dose. Doses were escalated sequentially in single pts (6 and 12 mg/m2) and 3–6 pts (≥ 25 mg/m2) cohorts according to a modified Fibonacci’s schema. Plasma pharmacokinetic (PK) profiles were obtained on days 1 and 18. Biomarkers were measured in PBMC’s (HSP70) and plasma (HER-2 ectodomain (HER-2 ECD)). Results: 30 pts (M/F: 14/16; median age 63, range 48–78) with colorectal cancer (11), pancreatic cancer (5), melanoma (5), ovarian (2), others (7) were treated with a median of 2 courses (range: 1–10). There was no dose-limiting toxicity up to 175 mg/m2. One pt at 175 mg/m2 died on study, but drug relation was unclear. Grade 1–2 gastrointestinal toxicities (nausea, vomiting, diarrhea) and serum creatinine elevation were observed. Severe toxicities (grade 3 but no grade 4) consisted of reversible hepatic enzyme elevation, hyperbilirubinemia, fatigue, anemia and hyperglycemia. There were no hematological toxicities. Plasma 17-AAG PK appeared dose-proportional (AUC, Cmax); CL (17 L/h/m2) and t1/2 (5.2 h) were dose independent and unchanged after repeated dosing (day 18). Post-treatment increases in HSP70 were observed in PBMCs and decreases in plasma HER-2 ECD were observed at doses ≥ 83 mg/m2. Minor tumor regressions were seen in 1 pt with duodenal cancer (83 mg/m2), 1 pt with gastric carcinoid (175 mg/m2) and 1 pt with melanoma (175 mg/m2). Conclusion: The threshold of biologic activity for CNF1010 administered by a twice a week schedule appears to be 83 mg/m2. This dosing regimen appears to be optimal and supported by the pharmacokinetic and pharmacodynamic data. The MTD has not yet been determined. Dose escalation of CNF1010 continues at 225 mg/m2.

[Table: see text]

A phase III trial of pemetrexed plus gemcitabine versus gemcitabine in patients with unresectable or metastatic pancreatic cancer

BACKGROUND

This randomized phase III study compared the overall survival (OS) of pemetrexed plus gemcitabine (PG) versus standard gemcitabine (G) in patients with advanced pancreatic cancer.

PATIENTS AND METHODS

Patients with unresectable locally advanced or metastatic pancreatic cancer and no prior systemic therapy (including 5-fluorouracil as a radiosensitizer) were randomized to receive either 1,250 mg/m(2) gemcitabine on days 1 and 8 plus pemetrexed 500 mg/m(2) after gemcitabine on day 8 (PG arm) of each 21-day cycle, or gemcitabine 1,000 mg/m(2) on days 1, 8 and 15 of each 28-day cycle (G arm).

RESULTS

Five hundred and sixty-five patients with well-balanced baseline characteristics were randomly assigned (283 PG, 282 G). OS was not improved on the PG arm (6.2 months) compared with the G arm (6.3 months) (P=0.8477). Progression-free survival (3.9 versus 3.3 months; P=0.1109) and time to treatment failure (3 versus 2.2 months; P=0.2680) results were similar. Tumor response rate (14.8% versus 7.1%; P=0.004) was significantly better on the PG arm. Grade 3 or 4 neutropenia (45.1% versus 12.8%), thrombocytopenia (17.9% versus 6.2%), anemia (13.9% versus 2.9%), febrile neutropenia (9.9% versus 0.4%; all P <0.001) and fatigue (15% versus 6.6%; P=0.002) were significantly more common on the PG arm. Four treatment-related deaths occurred on the PG arm and none in the G arm.

CONCLUSIONS

Pemetrexed plus gemcitabine therapy did not improve OS. Single-agent gemcitabine remains the standard of care for advanced pancreatic cancer.

Phase III trial of gemcitabine plus tipifarnib compared with gemcitabine plus placebo in advanced pancreatic cancer

PURPOSE

To determine whether addition of the farnesyltransferase inhibitor tipifarnib (Zarnestra, R115777; Johnson and Johnson Pharmaceutical Research and Development, Beerse, Belgium) to standard gemcitabine therapy improves overall survival in advanced pancreatic cancer.

PATIENTS AND METHODS

This randomized, double-blind, placebo-controlled study compared gemcitabine + tipifarnib versus gemcitabine + placebo in patients with advanced pancreatic adenocarcinoma previously untreated with systemic therapy. Tipifarnib was given at 200 mg bid orally continuously; gemcitabine was given at 1,000 mg/m(2) intravenously weekly x 7 for 8 weeks, then weekly x 3 every 4 weeks. The primary end point was overall survival; secondary end points included 6-month and 1-year survival rates, progression-free survival, response rate, safety, and quality of life.

RESULTS

Six hundred eighty-eight patients were enrolled. Baseline characteristics were well balanced between the two treatment arms. No statistically significant differences in survival parameters were observed. The median overall survival for the experimental arm was 193 v 182 days for the control arm (P =.75); 6-month and 1-year survival rates were 53% and 27% v 49% and 24% for the control arm, respectively; median progression-free survival was 112 v 109 days for the control arm. Ten drug-related deaths were reported for the experimental arm and seven for the control arm. Neutropenia and thrombocytopenia grade > or = 3 were observed in 40% and 15% in the experimental arm versus 30% and 12% in the control arm. Incidences of nonhematologic adverse events were similar in two groups.

CONCLUSION

The combination of gemcitabine and tipifarnib has an acceptable toxicity profile but does not prolong overall survival in advanced pancreatic cancer compared with single-agent gemcitabine.

A phase I and pharmacologic study of capecitabine and paclitaxel in breast cancer patients

BACKGROUND

Based on preclinical studies demonstrating that treatment with paclitaxel upregulates intratumoral thymidine phosphorylase (dTHdPase), which catalyzes the final step in the conversion of the oral fluoropyrimidine capecitabine to 5-fluorouracil (5-FU), as well as the overlapping spectra of activity for these agents, particularly in metastatic breast cancer, this phase I study evaluated the feasibility of administering capecitabine on an intermittent schedule in combination with paclitaxel in previously-treated patients with locally advanced or metastatic breast cancer. The study also sought to recommend doses for subsequent disease-specific studies, identify clinically significant pharmacokinetic interactions, and detect preliminary antitumor activity.

PATIENTS AND METHODS

Nineteen previously treated women with metastatic breast cancer whose prior treatment included neither paclitaxel or capecitabine received one hundred one courses of capecitabine and paclitaxel. Paclitaxel was administered as a three-hour intravenous (i.v.) infusion at a fixed dose of 175 mg/m2 and capecitabine was administered as 2 divided daily doses for 14 days followed by a seven-day rest period every 3 weeks. The dose of capecitabine was increased from a starting dose of 1650 mg/m2/d. The plasma sampling scheme in the first course permitted characterization of the pharmacokinetics of each agent given alone and concurrently to detect major pharmacokinetic interactions.

RESULTS

Palmar plantar erythrodysesthesia (hand foot syndrome) and neutropenia were the principal dose-limiting toxicities (DLT). Other toxicities included diarrhea and transient hyperbilirubinemia. Three of eight new patients treated with capecitabine 2000 mg/m2/d and paclitaxel 175 mg/m2 experienced DLT in the first course, whereas none of eleven new patients treated with capecitabine 1650 mg/m2/d and paclitaxel 175 mg/m2 developed DLT. Pharmacokinetic studies indicated that capecitabine did not grossly affect the pharmacokinetics of paclitaxel, and there were no major effects of paclitaxel on the pharmacokinetics of capecitabine and capecitabine metabolites. However, AUC values for the major 5-FU catabolite, fluorobeta-alanine (FBAL), were significantly lower in the presence of paclitaxel. Two complete and seven partial responses (56% response rate) were observed in sixteen patients with measurable disease; four of six patients whose disease was previously treated with high-dose chemotherapy and hematopoietic stem-cell support had major responses. Seven of nineteen patients had stable disease as their best response.

CONCLUSIONS

Recommended combination doses of capecitabine on an intermittent schedule and paclitaxel are capecitabine 1650 mg/m2/d orally for 14 days and paclitaxel 175 mg/m2 i.v. every 3 weeks. The favorable preclinical interactions between capecitabine and paclitaxel, as well as the acceptable toxicity profile and antitumor activity in patients with metastatic breast cancer, support further clinical evaluations to determine an optimal role for the combination of capecitabine and paclitaxel in breast cancer and other relevant malignancies.

MGI 114: augmentation of antitumor activity when combined with topotecan

PURPOSE

6-Hydroxymethylacylfulvene (HMAF; MGI 114; Irofulven) is a semisynthetic analogue of the mushroom toxin illudin S that has been shown to be a potent cytotoxic agent with an improved therapeutic index compared with its parent compound. The studies were conducted to evaluate the antitumor activity of MGI 114 as a single agent and in combination with topotecan against pediatric solid tumor cell lines and xenograft models.

MATERIALS AND METHODS

In vitro studies were designed to determine the cytotoxic potential of MGI 114 using the MTT assay and 13 pediatric tumor cell lines. In addition, combination in vitro studies were performed with MGI 114 and topotecan to generate isoeffect plots. Single agent and combination in vivo studies were also performed using MGI 114 against rhabdomyosarcoma and neuroblastoma xenograft models.

RESULTS

After a 1-hour exposure to MGI 114, the mean IC50 (+/-standard error of mean) for medulloblastoma, neuroblastoma, Ewing sarcoma/primitive neuroectodermal tumor, and rhabdomyosarcoma cell lines were 1.58+/-0.51, 1.60+/-0.82, 1.18+/-0.08, and 3.99+/-1.69 microg/mL, respectively. When tumor cells were exposed concurrently to MGI 114 and topotecan, evidence of synergy was observed in 10 of 12 (83%) cell lines. Single agent and combination in vivo studies with MGI 114 showed that this agent had substantial, and at times curative, antitumor activity against rhabdomyosarcoma and neuroblastoma xenograft tumors.

CONCLUSIONS

These data suggest that MGI 114 has significant efficacy as a single agent in preclinical studies against pediatric tumors. In addition, based on previous reports and the results presented here, combining MGI 114 with topotecan appears to be an attractive approach to the treatment of pediatric malignancies. After completion of the pediatric phase I studies of MGI 114, consideration should be given to phase II single agent and phase I combination studies with a topoisomerase I inhibitor such as topotecan or irinotecan.

Effect of telomere and telomerase interactive agents on human tumor and normal cell lines

Shortening of telomeres along with an up-regulation of telomerase is implicated in the immortality of tumor cells. Targeting either telomeres or telomerase with specific compounds has been proposed as an anticancer strategy. Because telomerase activity and telomeres are found in normal cells, telomere or telomerase targeting agents could induce side effects in normal tissues. We evaluated the effects of telomere and telomerase interactive agents in human tumor and normal cell lines to try to determine the potential side effects those agents might induce in patients. Toxicity of the G-quadruplex interactive porphyrins (TMPyP4, TMPyP2) and azidothymidine (AZT) were tested using a cell-counting technique against normal human cell lines (CRL-2115 and CRL-2120, fibroblasts; NHEK-Ad, adult keratinocytes; CCL-241, small intestinal cells; NCM 460, colonic mucosal epithelial cells) and human tumor cell lines (MDA-MB 231 and Hs 578T, breast cancer; SK-N-FI, neuroblastoma; HeLa, cervix cancer; MIA PaCa-2, pancreatic cancer; HT-29 and HCT-116, colon cancer; DU 145, prostatic cancer cell line). Telomerase activity of these cell lines was measured by a non-PCR-based conventional assay. The effects of TMPgammaP2, TMPyP4, and AZT were also evaluated against normal human bone marrow specimens, using a granulocyte-macrophage colony-forming assay (CFU-GM). AZT showed very low cytotoxic effects against normal and tumor cell lines, with the IC50 values above 200 microM. The IC50 values for TMPyP2 and TMPyP4 in normal human cell lines were in the range of 2.9-48.3 microM and 1.7-15.5 microM, respectively, whereas in tumor cell lines the IC50 values were 11.4-53 microM and 9.0-28.2 microM, respectively. Within the tissue types, keratinocytes were more sensitive to TMPyP4 than fibroblasts, and small intestinal cells were more sensitive than colonic mucosal epithelial cells. The IC50 for TMPyP2 and TMPyP4 in the normal marrow colony-forming assays were 19.3 +/- 5.1 microM and 47.9 +/-1.0 microM, respectively. In conclusion, the in vitro cytotoxicity of the telomere interactive agent TMPyP4 is comparable in human tumor and normal cell lines, which indicates that TMPyP4 could have effects on normal tissues.

Comparison of in vitro activities of camptothecin and nitidine derivatives against fungal and cancer cells

The activities of a series of camptothecin and nitidine derivatives that might interact with topoisomerase I were compared against yeast and cancer cell lines. Our findings reveal that structural modifications to camptothecin derivatives have profound effects on the topoisomerase I-drug poison complex in cells. Although the water-soluble anticancer agents topotecan and irinotecan are less active than the original structure, camptothecin, other derivatives or analogs with substitutions that increase compound solubility have also increased antifungal activities. In fact, a water-soluble prodrug appears to penetrate into the cell and release its active form; the resulting effect in complex with Cryptococcus neoformans topoisomerase I is a fungicidal response and also potent antitumor activity. Some of the compounds that are not toxic to wild-type yeast cells are extremely toxic to the yeast cells when the C. neoformans topoisomerase I target is overexpressed. With the known antifungal mechanism of a camptothecin-topoisomerase I complex as a cellular poison, these findings indicate that drug entry may be extremely important for antifungal activity. Nitidine chloride exhibits antifungal activity against yeast cells through a mechanism(s) other than topoisomerase I and appears to be less active than camptothecin analogs against tumor cells. Finally, some camptothecin analogs exhibit synergistic antifungal activity against yeast cells in combination with amphotericin B in vitro. Our results suggest that camptothecin and/or nitidine derivatives can exhibit potent antifungal activity and that the activities of camptothecin derivatives with existing antifungal drugs may be synergistic against pathogenic fungi. These new compounds, which exhibit potent antitumor activities, will likely require further structural changes to find more selective activity against fungal versus mammalian cells to hold promise as a new class of antifungal agents.

Phase I evaluation of ISIS 3521, an antisense oligodeoxynucleotide to protein kinase C-alpha, in patients with advanced cancer

PURPOSE

To determine the maximum-tolerated dose (MTD) and pharmacologic behavior of ISIS 3521 (ISI 641A), an antisense phosphorothioate oligonucleotide to protein kinase C-alpha.

PATIENTS AND METHODS

Thirty-six patients with advanced cancer received 99 cycles of ISIS 3521 (0.15 to 6.0 mg/kg/d) as a 2-hour intravenous infusion administered three times per week for 3 consecutive weeks and repeated every 4 weeks. Plasma and urine sampling was performed during the first week of treatment and subjected to capillary gel electrophoresis to determine full-length antisense oligonucleotide in addition to chain-shortened metabolites.

RESULTS

Drug-related toxicities included mild to moderate nausea, vomiting, fever, chills, and fatigue. Hematologic toxicity was limited to thrombocytopenia (grade 1, four patients; grade 2, one patient; grade 3, one patient). There was no relationship between dose, maximum concentration of the drug (C(max)), or area under the plasma concentration versus time curve (AUC) and coagulation times or complement levels. Dose escalation was discontinued because of the attainment of peak plasma concentrations, which approached that associated with complement activation in primates. Two patients with non-Hodgkin's lymphoma who completed 17 and nine cycles of therapy achieved complete responses. The pharmacokinetic profile of ISIS 3521 revealed a short elimination half-life (18 to 92 minutes), as well as a dose-dependent decrease in clearance and dose-dependent increases in C(max), AUC, and elimination half-life.

CONCLUSION

No dose-limiting toxicity of ISIS 3521 was identified, and clinical activity was observed. A short elimination half-life was identified, which suggests that alternate schedules with prolonged administration may be necessary for further clinical development.

American Society of Clinical Oncology clinical practice guidelines for the use of chemotherapy and radiotherapy protectants

PURPOSE

Because toxicities associated with chemotherapy and radiotherapy can adversely affect short- and long-term patient quality of life, can limit the dose and duration of treatment, and may be life-threatening, specific agents designed to ameliorate or eliminate certain chemotherapy and radiotherapy toxicities have been developed. Variability in interpretation of the available data pertaining to the efficacy of the three United States Food and Drug Administration-approved agents that have potential chemotherapy- and radiotherapy-protectant activity-dexrazoxane, mesna, and amifostine-and questions about the role of these protectant agents in cancer care led to concern about the appropriate use of these agents. The American Society of Clinical Oncology sought to establish evidence-based, clinical practice guidelines for the use of dexrazoxane, mesna, and amifostine in patients who are not enrolled on clinical treatment trials.

METHODS

A multidisciplinary Expert Panel reviewed the clinical data regarding the activity of dexrazoxane, mesna, and amifostine. A computerized literature search was performed using MEDLINE. In addition to reports collected by individual Panel members, all articles published in the English-speaking literature from June 1997 through December 1998 were collected for review by the Panel chairpersons, and appropriate articles were distributed to the entire Panel for review. Guidelines for use, levels of evidence, and grades of recommendation were reviewed and approved by the Panel. Outcomes considered in evaluating the benefit of a chemotherapy- or radiotherapy-protectant agent included amelioration of short- and long-term chemotherapy- or radiotherapy-related toxicities, risk of tumor protection by the agent, toxicity of the protectant agent itself, quality of life, and economic impact. To the extent that these data were available, the Panel placed the greatest value on lesser toxicity that did not carry a concomitant risk of tumor protection.

RESULTS AND CONCLUSION

Mesna: (1) Mesna, dosed as detailed in these guidelines, is recommended to decrease the incidence of standard-dose ifosfamide-associated urothelial toxicity. (2) There is insufficient evidence on which to base a guideline for the use of mesna to prevent urothelial toxicity with ifosfamide doses that exceed 2.5 g/m(2)/d. (3) Either mesna or forced saline diuresis is recommended to decrease the incidence of urothelial toxicity associated with high-dose cyclophosphamide use in the stem-cell transplantation setting. Dexrazoxane: (1) The use of dexrazoxane is not routinely recommended for patients with metastatic breast cancer who receive initial doxorubicin-based chemotherapy. (2) The use of dexrazoxane may be considered for patients with metastatic breast cancer who have received a cumulative dosage of 300 mg/m(2) or greater of doxorubicin in the metastatic setting and who may benefit from continued doxorubicin-containing therapy. (3) The use of dexrazoxane in the adjuvant setting is not recommended outside of a clinical trial. (4) The use of dexrazoxane can be considered in adult patients who have received more than 300 mg/m(2) of doxorubicin-based therapy for tumors other than breast cancer, although caution should be used in settings in which doxorubicin-based therapy has been shown to improve survival because of concerns of tumor protection by dexrazoxane. (5) There is insufficient evidence to make a guideline for the use of dexrazoxane in the treatment of pediatric malignancies, with epirubicin-based regimens, or with high-dose anthracycline-containing regimens. Similarly, there is insufficient evidence on which to base a guideline for the use of dexrazoxane in patients with cardiac risk factors or underlying cardiac disease. (6) Patients receiving dexrazoxane should continue to be monitored for cardiac toxicity. Amifostine: (1) Amifostine may be considered for the reduction of nephrotoxicity in patients receiving cisplatin-based chemoth

Evidence of enhanced in vivo activity using tirapazamine with paclitaxel and paraplatin regimens against the MV-522 human lung cancer xenograft

PURPOSE

Tirapazamine (3-amino-1,2,4-benzotriazine 1,4-dioxide; SR 4233) is a bioreductive agent that exhibits relatively selective cytotoxicity towards cells under hypoxic conditions and can enhance the antitumor activity of many standard oncolytics. In the present study we examined the interaction between tirapazamine in vivo with paclitaxel and paraplatin in two- and three-way combination studies using the MV-522 human lung carcinoma xenograft model.

METHODS

Agents were administered as a single i.p. bolus, with tirapazamine being given 3 h prior to paclitaxel, paraplatin, or their combination. Tumor growth inhibition (TGI), final tumor weights, partial and complete responses, and time to tumor doubling were determined after drug administration.

RESULTS

Tirapazamine as a single agent was ineffective against this human lung tumor model. A substantial increase in TGI was seen in animals treated with the triple-agent regimen (tirapazamine-paclitaxel-paraplatin) compared to animals treated with double-agent regimens that did not include tirapazamine. The addition of tirapazamine to paclitaxel-paraplatin therapy resulted in a 50% complete response rate; there were no complete responses seen when only the paclitaxel-paraplatin combination was administered. Time to tumor doubling was also significantly improved with the addition of tirapazamine to the paclitaxel and paraplatin combinations. Tirapazamine did not increase the toxicity of paclitaxel, paraplatin, or their combinations as judged by its minimal impact on body weight and the fact that no toxic deaths were observed with tirapazamine-containing regimens.

CONCLUSIONS

These results are important since recent studies have suggested that the combination of paclitaxel and paraplatin may be particularly active in patients with advanced stage non-small-cell lung cancer. Since tirapazamine can significantly improve efficacy, but does not appear to enhance the toxicity of paclitaxel and paraplatin, its evaluation in future clinical trials in combination with paclitaxel-paraplatin-based therapy appears warranted.

An in vitro assessment of the antineoplastic potential of 2H-1,3-oxazine-2,6(3H)-dione (3-oxauracil), a novel pyrimidine

The pyrimidine (uracil) analogue 3-oxauracil (OU) previously had been shown to completely inhibit the growth of E. coli B and decrease by 96% the replication of herpes simplex virus type 2 when present in the culture fluid at a concentration of 10(2) microM. Limited in vivo studies in mice demonstrated antiviral effects without significant toxicity when given i.p. daily for two weeks at a concentration of 3.23 mg/kg. However, the antineoplastic properties of OU were unknown. We assessed the ability of OU to inhibit the proliferation of various human tumor cell lines (3 pancreatic, 1 colon, 1 neuroendocrine, and 1 lung) in an in vitro radiometric (Bactec) system. In the pancreatic lines (RWP-2, MiaPaCa-2, and PANC-1), the colon line (HT-29), the neuroendocrine line (COLO 320DM), and the lung cancer cell line (SK-MES-1), OU at a concentration of 10(3) microM, produced a dramatic decrease in percent cell survival. When compared with cytotoxic drugs of choice for these tumor cells (gemcitabine, 5-fluorouracil, and adriamycin, respectively) a significantly higher concentration of OU was required usually to achieve comparable results with two exceptions. These were the HT-29 and the COLO 320DM cell lines. These results indicate OU has significant (p < 0.05) cytotoxic activity against pancreatic, colon, neuroendocrine, and nonsmall cell lung cancer lines, when compared to untreated control cultures. Additional in vivo testing of this potential antineoplastic agent is warranted.

[Inhibition of telomeres and telomerase. Seeking for new anticancer drugs]

Human telomeres are guanine-rich regions (TTAGGG) located at the end of chromosomes that protect them against aberrant recombination and protect DNA from exonuclease degradation. Telomeres maintenance is performed by telomerase, a RNA-dependent DNA polymerase. Telomerase is over-expressed in a large number of cancers that have short telomeres whereas it is not expressed in somatic cells that have long telomeres. Therefore, this differential gives a rational for further evaluation of telomerase and telomeres as targets for identification of new anticancer drugs. Current strategies aim to identify new drugs with specific activity against telomerase and telomeres. In this review we will discuss the biological and clinical approaches as well as relevant tumor models for studying the biological effects of telomerase inhibition and telomere targeting in vitro and in vivo.

Anti-tumor efficacy and biodistribution of intravenous polymeric micellar paclitaxel

The purpose of this study was to evaluate the diblock copolymer poly(DL-lactide)-block-methoxy polyethylene glycol as an i.v. delivery vehicle for paclitaxel. Nude mice were implanted s.c. with fragments of MV-522 lung carcinomas and treated with paclitaxel on a daily x 5 schedule when tumors were approximately 5 x 5 mm in size. Cremophor paclitaxel or polymeric micellar paclitaxel were given i.p. or i.v. at the maximum tolerated dose (Cremophor paclitaxel MTD: 20 mg/kg/day i.v. or i.p.; micellar paclitaxel MTD: 25 mg/kg/day i.v. or 100 mg/kg/day i.p.). The tumors were measured using callipers during the experiment and accurately weighted at the end. Two biodistribution studies were carried out. In one study, the nude mice were given micellar paclitaxel at a dose of 25 mg/kg i.v. or 100 mg/kg i.p. in another study, BDF-1 mice were given either micellar paclitaxel or Cremophor paclitaxel at a dose of 20 mg/kg i.v. The mice were sacrificed after a given time and the organs were harvested. Paclitaxel in the organs was extracted with acetonitrile and analyzed using HPLC. Tumor growth inhibitions of 98.5 and 98.7% were obtained from i.v. administered micellar paclitaxel and Cremophor paclitaxel at their MTDs, respectively. Micellar paclitaxel was more efficacious i.p. (98.7% tumor growth inhibition) than Cremophor paclitaxel i.p. (83.0% tumor growth inhibition) at their MTDs. The highest concentrations of paclitaxel were found in the liver after administration of paclitaxel formulations. Paclitaxel was also found in spleen, kidney, lung and blood, in order of decreasing concentration. The preliminary results indicate that polymeric micellar paclitaxel could be a clinically useful chemotherapeutic formulation.

Docetaxel in combination with fluorouracil: study design and preliminary results

The relatively recent introduction of a new class of chemotherapeutic agents--the taxoids--has raised hope of improved survival for patients with advanced or metastatic cancer. Following encouraging preclinical results of taxoid combinations, this phase I, nonrandomized trial was designed to evaluate a 1-hour intravenous infusion of docetaxel (Taxotere) on day 1 combined with fluorouracil (5-FU) as a daily intravenous bolus for 5 consecutive days. To date, 27 patients with advanced solid neoplasms have received 86 courses of docetaxel/5-FU at the following dose levels: 25/100, 35/150, 50/200, 60/200, and 60/300 mg/m2. Preliminary results showed no unexpected toxicities, and the principal toxicity was neutropenia of short duration. A treatment regimen of 60 mg/m2 docetaxel on day 1 and 300 mg/m2 of 5-FU given for 5 days, with a single course length of 28 days, is projected as the maximum tolerated dose.

Mitoguazone therapy in patients with refractory or relapsed AIDS-related lymphoma: results from a multicenter phase II trial

PURPOSE

Patients with AIDS-related lymphoma usually have extensive lymphomatous disease, with relatively frequent involvement of the CNS. Approximately half may achieve complete remission after chemotherapy. Mitoguazone, an inhibitor of polyamine biosynthesis, has demonstrated efficacy in patients with de novo recurrent lymphoma. The drug is relatively nonmyelotoxic and may cross the blood-brain barrier. The current study was designed to assess the safety and potential efficacy of mitoguazone in patients with relapsed or refractory AIDS-lymphoma.

PATIENTS AND METHODS

Thirty-five patients were accrued, all of whom had failed one (51%) or multiple (two to six) prior regimens. Mitoguazone (600 mg/m2) was given intravenously on days 1 and 8, and then every 2 weeks, until best response, progression, or toxicity.

RESULTS

The median age was 39 years. High-grade lymphoma was diagnosed in 29 patients (83%). Extranodal disease was present in 30 patients (86%), with multiple extranodal sites (two to seven) in 18 (51%). The median CD4 cell count at study entry was 66/dL (range, zero to 549). Twenty-six patients were assessable for response. The objective response rate was 23% (95% confidence interval [CI], 6.9 to 39.3), with complete remission in three patients (11.5%), and partial remission (PR) in three patients (11.5%). Six patients experienced stable disease. Median survival from study entry was 2.6 months for the group as a whole; 21.5 months (range, 3.8 to 29.1) in complete responders, 5.6 months (range, 3.8 to 34.8) in partial responders. The most common toxicities occurred solely during drug infusion and included vasodilation (63%), paresthesia (86%), and somnolence (17%). Fourteen patients (40%) experienced nausea and 16 (46%) vomiting (grade 3 in one). Ten patients (29%) developed stomatitis, including grade 3 in two and grade 4 in one. Seven patients (20%) developed neutropenia, with grade 4 in one. Thrombocytopenia occurred in nine patients (26%). While on study, three patients developed sepsis, four had pneumonia, and two developed opportunistic infections.

CONCLUSION

Mitoguazone is an effective agent in patients with multiply relapsed or refractory AIDS-related lymphoma, with acceptable toxicity. Further study in patients with newly diagnosed disease is warranted.

An investigation of the antitumour activity and biodistribution of polymeric micellar paclitaxel

PURPOSE

To evaluate in vitro cytotoxicity, in vivo antitumour activity and biodistribution of a novel polymeric (poly(DL-lactide)-block-methoxy polyethylene glycol) micellar paclitaxel.

METHODS

Hs578T breast, SKMES non-small-cell lung, and HT-29 colon human tumour cells were exposed, either for 1 h or continuously, to conventionally formulated paclitaxel (Cremophor paclitaxel) or polymeric micellar paclitaxel. After a period of incubation, cytotoxicity was measured using a radiometric system. In the in vivo antitumour study, B6D2F1 mice, bearing P388 leukaemia tumour intraperitoneally (i.p.), were treated with polymeric micellar paclitaxel or Cremophor paclitaxel by i.p. injection. The number of deaths and body weights were recorded. In the biodistribution study, CD-1 mice were given micellar paclitaxel i.p. at a dose of 100 mg/kg. The mice were sacrificed after a given time and the organs were harvested. Paclitaxel in the organs was extracted by acetonitrile and analysed using HPLC.

RESULTS

The polymeric micellar paclitaxel showed similar in vitro cytotoxicity to Cremophor paclitaxel against the tumour cell lines. The polymeric micellar formulation of paclitaxel produced a fivefold increase in the maximum tolerated dose (MTD) as compared with Cremophor paclitaxel when administered i.p. In addition, micellar paclitaxel was more efficacious in vivo when tested in the murine P388 leukaemia model of malignancy than Cremophor paclitaxel when both were administered i.p. at their MTDs. Micellar paclitaxel-treated animals had an increased survival time and, importantly, long-term survivors (20% of those tested) were obtained only in the polymeric paclitaxel formulation group. Biodistribution studies indicated that a significant amount of paclitaxel could be detected in blood, liver, kidney, spleen, lung and heart of mice after i.p. dosing of the polymeric micellar paclitaxel formulation.

CONCLUSION

These preliminary results indicate that polymeric micellar paclitaxel could be a clinically useful chemotherapeutic formulation.

New anticancer agents in clinical development

A better understanding of the biology and biochemistry of the cancer cell has led to the development of various promising new antineoplastic compounds that are now undergoing phase I, II, and III clinical testing. These drugs include topoisomerase I inhibitors, such as camptothecin and its analogs 9-aminocamptothecin, irinotecan, and topotecan; and the paclitaxel analog docetaxel. The authors discussed these new agents last month. In Part 2 of their article, they describe gemcitabine, an antimetabolite structurally related to cytarabine; fluorouracil prodrugs and other thymidylate synthase (TS) inhibitors, and new approaches to anticancer therapy, such as angiogenesis inhibitors, differentiating agents, signal transduction inhibitors, and gene therapy.

Aberrant subcellular localization of BRCA1 in breast cancer

The BRCA1 gene product was identified as a 220-kilodalton nuclear phosphoprotein in normal cells, including breast ductal epithelial cells, and in 18 of 20 tumor cell lines derived from tissues other than breast and ovary. In 16 of 17 breast and ovarian cancer lines and 17 of 17 samples of cells obtained from malignant effusions, however, BRCA1 localized mainly in cytoplasm. Absence of BRCA1 or aberrant subcellular location was also observed to a variable extent in histological sections of many breast cancer biopsies. These findings suggest that BRCA1 abnormalities may be involved in the pathogenesis of many breast cancers, sporadic as well as familial.

New anticancer agents in clinical development

A better understanding of the biology and biochemistry of the cancer cell has led to the development of various promising new antineoplastic compounds that are now undergoing phase I, II, and III clinical testing. These drugs include topoisomerase I inhibitors, such as camptothecin and its analogs 9-aminocamptothecin, irinotecan, and topotecan; the paclitaxel analog docetaxel; gemcitabine, an antimetabolite structurally related to cytarabine; and fluorouracil prodrugs and other thymidylate synthase (TS) inhibitors. Another exciting approach to cancer treatment is the use of agents that induce a less malignant state by altering cellular phenotype. Such agents include angiogenesis inhibitors, differentiating agents, signal transduction inhibitors, and gene therapy.