G. Hartung

High single-drug activity of nelarabine in relapsed T-lymphoblastic leukemia/lymphoma offers curative option with subsequent stem cell transplantation

Nelarabine, a purine analog with T-cell specific action, has been approved for relapsed/refractory T-cell acute lymphoblastic leukemia/lymphoma (ALL/LBL). This is a report of a single-arm phase 2 study conducted in adults (18-81 years of age) with relapsed/refractory T-ALL/LBL. After 1 or 2 cycles, 45 of 126 evaluable patients (36%) achieved complete remission (CR), 12 partial remission (10%), and 66 (52%) were refractory. One treatment-related death was observed, and 2 patients were withdrawn before evaluation. A total of 80% of the CR patients were transferred to stem cell transplantation (SCT). Overall survival was 24% at 1 year (11% at 6 years). After subsequent SCT in CR, survival was 31% and relapse-free survival 37% at 3 years. Transplantation-related mortality was 11%. Neurologic toxicities of grade I-IV/grade III-IV were observed in 13%/4% of the cycles and 16%/7% of the patients. This largest study so far with nelarabine in adults showed impressive single-drug activity in relapsed T-ALL/T-LBL. The drug was well tolerated, even in heavily pretreated patients. A high proportion of CR patients were transferred to SCT with low mortality but a high relapse rate. Exploration of nelarabine in earlier stages of relapse (eg, increasing minimal residual disease), in front-line therapy, and in combination is warranted.

Pharmacokinetics of methotrexate-albumin conjugates in tumor-bearing rats.

Linking chemotherapeutic drugs to a macromolecular carrier system may enhance tumor targeting, reduce toxicity and overcome drug resistance mechanisms. As an elementary model to evaluate the pharmacological properties of macromolecular drug carrier systems we chose rat serum albumin (RSA) for carrier and methotrexate (MTX) as antineoplastic drug. The conjugation procedure yielded conjugates with an approximate 1:1 molar loading rate (MTX(1)-RSA). In the first part of the study a residualizing [111ln]DTPA protein label was used for mapping in vivo the catabolic sites of the native carrier protein and of the MTX(1)-RSA drug conjugate in Walker 256 carcinosarcoma bearing rats. The tumor accumulation was about 14% of the injected dose for the RSA and MTX(1)-RSA tracers after 24 h. Tracer entrapment by organs with an active mononuclear phagocyte system was low (liver below 7% and spleen below 1.5% of the injected dose after 24 h). The 1:1 conjugation of MTX to RSA did not decisively alter the pharmacokinetic properties nor the tumor or tissue distribution of the native carrier protein RSA. In the second part of the study the different properties of the MTX(1)-RSA conjugate were compared with MTX in vivo. About 2 mg MTX/ kg body weight either of the drug conjugate or of the original drug were injected after being additionally spiked with radiolabeled tracers. Plasma concentrations were simultaneously determined by immunological and radioactive means. After 24 h about 12% MTX(1)-RSA was found in circulation compared to 0.03% MTX. Favorable tumor accumulation rates of about 14% were achieved for MTX(1)-RSA versus 0.04% for MTX. About 45-fold more of the injected dose of [3H]MTX accumulated in the liver as compared to the tumor (1.5 versus 0.03%) after 24 h. Conjugation of MTX to RSA reversed this ratio in favor of the tumor to 1:1.4 (13.6 versus 9.6%). In conclusion, the potential therapeutic benefit of the MTX(1)-RSA conjugate lies in its very long tumor exposure time and its improved tumor accumulation rate compared to conventional MTX. In addition the conjugation to albumin might enhance the therapeutic effects over those achieved by long-term continuous infusion of MTX, as MTX(1)-RSA enters the cells by a different uptake mechanism. This might also help to circumvent MTX resistance mechanisms, such as a reduction in folate receptor numbers or impaired MTX polyglutamylation.

Pre-clinical evaluation of a methotrexate–albumin conjugate (MTX-HSA) in human tumor xenografts in vivo†

Methotrexate covalently bound to human serum albumin in a 1:1 molar ratio (MTX‐HSA) is a new macromolecular drug which is currently being studied in phase I clinical trials by the German Association for Medical Oncology (AIO) Phase I/II study group. Previous studies have shown that MTX‐HSA differs favorably from unbound MTX in terms of plasma half‐life time, tumor accumulation of albumin and uptake mechanisms into cancer cells. To achieve optimal drug efficacy, repeated treatment cycles were necessary. To evaluate the anti‐tumor activity of MTX‐HSA and MTX in pre‐clinical in vivo models, we selected 7 solid human tumor xenografts growing s.c. in nude mice and administered drug either i.p. or i.v. weekly for 3 weeks. The maximal tolerated dose (MTD) of MTX‐HSA in nude mice was 12.5 mg/kg given i.p. on days 1, 8 and 15, whereas the MTD for free MTX was 100 mg/kg given i.v. MTX‐HSA was significantly more active (p > 0.01) than MTX in 3 models. In the soft tissue sarcoma SXF 1301, MTX‐HSA effected complete remission/cure after a single injection, whereas free MTX resulted in short‐lasting, partial tumor regression. In the prostate‐cancer model PRXF PC3M, MTX‐HSA produced growth inhibition of 92.8% of control or an optimal test/control (T/C) of 7.2% compared to a T/C of 20.8% for MTX (p = 0.05). In the osteosarcoma model SXF 1410, optimal T/C values were 10.2% and 14.5%, respectively (p = 0.025). In lung cancers LXFE 409 and LXFL 529, bladder cancer BXF 1258 and breast cancer MAXF 449, both compounds were inactive. The improved therapeutic effects seen in 3 xenograft models under MTX‐HSA treatment are promising and might be due to specific accumulation of the compound in solid tumors owing to their enhanced permeability and retention effect. Thus, clinical development of MTX‐HSA will continue and sarcomas as well as prostate cancers will be included as potential target tumors for upcoming clinical phase II trials.

ALBUMIN-BASED DRUG CARRIERS : COMPARISON BETWEEN SERUM ALBUMINS OF DIFFERENT SPECIES ON PHARMACOKINETICS AND TUMOR UPTAKE OF THE CONJUGATE

Albumin-based drug carrier systems have been developed in the field of chemotherapy to improve the passive tumor targeting properties of anti-cancer drugs. Usually, serum albumins of different species are used as carrier proteins, mostly of bovine (BSA), human (HSA) or rat (RSA) origin. The resulting albumin conjugates are often tested for anticancer activity in heterologous tumor models. No data is available whether the choice of the albumin species might influence the pharmacokinetics or the tumor uptake rates of the conjugates in vivo. Residualizingly ([111In]DTPA) radiolabeled RSA, BSA or HSA were administered to Walker-256 carcinoma-bearing rats. No significant difference was found in the absolute or the weight-adjusted tumor uptake rates of the three albumin tracers. The tumors were the major catabolic sites accumulating 14-18% of the injected dose (ID). Low hepatic uptake rates were determined for all albumins (below 100% ID). Minor differences were found for hepatic uptake in favor of the autologous RSA (5.8% ID) versus HSA (6.9%) and BSA (8.0%). These differences might have occurred during the commercial preparation or the radiolabeling of the different batches. In addition, there are structural differences between the three albumins, which might have contributed, despite high sequence homologies above 70% for RSA, HSA and BSA. These minor differences in the distribution patterns of RSA, HSA or BSA might not decisively influence the results of drug targeting experiments in rats. For further studies with albumin conjugates, HSA was chosen as drug carrier in rodent animal models when considering later human use. In rats or nude mice multiple injections of various HSA-drug conjugates were well tolerated without signs of allergy or anaphylaxis.

Antitumor activity of methotrexate-albumin conjugates in rats bearing a Walker-256 carcinoma.

We have recently reported that albumin accumulates in solid tumors and serves there as a source of nitrogen and energy. Methotrexate‐albumin conjugates [MTX(1)‐RSA] derivatized at a molar ratio of 1:1 differ favorably from original MTX in terms of plasma presence and tumor uptake. The purpose of this study was to evaluate the therapeutic efficacy of these novel conjugates in a comparative study with low m.w. MTX in Sprague‐Dawley rats bearing a Walker‐256 carcinoma. The maximum tolerated dose (MTD) for MTX and MTX(1)‐RSA was determined (2 mg/kg based on MTX injected on days 1, 3 and 8). The tumor‐bearing rats received injections of either the MTD or MTD/2 of MTX, MTX‐albumin or mixtures containing the MTD/2 or MTD/4 of both MTX and MTX‐albumin. No toxic side effects were observed. Cure rate and tumor growth retardation were slightly better for the conjugate compared with MTX alone in the MTD group (16 complete remissions vs. 14 of 20 rats). The best results were achieved for the combination treatment with MTX and MTX‐albumin, with complete remission in all 20 rats. In conclusion, MTX‐albumin conjugates show therapeutic activity in vivo without toxic side effects. Additive effects were observed for a combination of MTX‐albumin and MTX. These effects might be caused by the much longer tumor exposition time of the conjugate in conjunction with a different route of uptake (pinocytosis for MTX‐albumin vs. folate receptors for MTX). Int. J. Cancer76:884–890, 1998.© 1998 Wiley‐Liss, Inc.

METHOTREXATE-ALBUMIN CONJUGATE CAUSES TUMOR GROWTH DELAY IN DUNNING R3327 HI PROSTATE CANCER-BEARING RATS

Based on the rationale of a preferred albumin uptake by tumors, conjugates comprising of rat serum albumin (RSA) as a drug carrier and of methotrexate (MTX) as chemotherapeutic drug were prepared. For a comparative study of MTX-RSA and MTX we chose a slow growing Dunning R3327 HI prostate cancer model. In a radiopharmacologic study blood kinetics and the tumor and organ distribution pattern of residualizingly labeled MTX-RSA were determined, and were found to be similar to that of residualizingly labeled RSA. The MTD was established for Copenhagen rats at a total four injections of 2 mg/kg MTX or MTX-RSA administered at days 0, 4, 8 and 12. Tumor volume measurements and tumor removal showed a small non-significant growth delay in the MTX treatment group, suggesting MTX resistance for the Dunning R3327 HI prostate carcinoma. In contrast, treatment with MTX-RSA resulted in a significant (50%) growth inhibition of the Dunning R3327 HI tumor. The cellular mechanisms responsible for MTX resistance in Dunning HI tumor cells is not known. The improved therapeutic effects seen during MTX-RSA treatment in this slow growing adenocarcinoma might be a result of prolonged tumor exposure time and an altered cellular uptake by a lysosomal route. MTX-albumin conjugates have shown antitumor activity exceeding that of MTX in several tumor xenografts in nude mice, including human prostate cancer. The recently initiated clinical development of MTX-human serum albumin will be continued and cancer of the prostate will be included as a potential target tumor during further clinical phase II testing.

Pseudomembranous tracheobronchial aspergillosis: a rare manifestation of invasive aspergillosis in a non‐neutropenic patient with Hodgkin's disease

Summary  Pseudomembranous tracheobronchial aspergillosis coincident with systemic pulmonary aspergillosis represents a rare manifestation of fungal infection in immunocompromized hosts. We report on a patient with recurrent Hodgkins disease, showing this infectious pattern after treatment with corticosteroids within the antineoplastic schedule, whereas neutropenia – the main risk factor for mold infections – had not occurred. An impaired number of helper T lymphocytes was merely detected as an additional, but hypothetical risk factor, when investigating the status of immunosuppression. Treated systemically with amphotericin B, the patient recovered quickly, although reported mortality rates are disastrous. What is crucial for the clinical management is an early diagnosis by bronchoscopy and cultural proof of the pathogen followed by an adequate antifungal treatment.

Combination of Bolus 5-Fluorouracil, Folinic Acid and Mitomycin C in Advanced Gastric Cancer: Results of a Phase II Trial

Background: Gastric carcinoma still is a worldwide major cause of cancer death. Although various chemotherapy schedules yielded high response rates, median survival rarely exceeds 8–10 months. Many regimens are inevitably associated with significant toxicity which jeopardizes their value as palliative treatment, especially in patients with reduced performances status. Therefore, we initiated a phase II study for the treatment of advanced gastric carcinoma using a bolus regimen with mitomycin C (MMC), 5-fluorouracil (5-FU) and folinic acid (FA), allowing the enrollment of elderly patients or those with reduced performance status (WHO grade 2). Patients and Methods: Between 1996 and 1998 we recruited a total of 58 patients with advanced gastric cancer to receive bolus MMC 3 mg/m2, 5-FU 450 mg/m2, and FA 100 mg/m2 on days 1–3. Treatment was repeated on day 22. 53 patients met the inclusion criteria: male n = 36, female n =17; median age 65 (range 26–81); mean WHO status 1 (range 0–2). Results: Out of 53 patients 50 were evaluable for response, all 58 patients who received therapy were evaluable for toxicity. Eleven patients (22%) achieved partial remission (95% CI: 11.5 –36.0%), 24 (48%) no change and 15 (30%) were progressive. Median overall survival was 11.5 months, the median time to progression 6.0 months. Out of 290 treatment cycles the worst toxicities observed (WHO 2/3/4) were as follows: anemia 13/3/1, leukopenia 19/1/1, thrombopenia 11/3/0, nausea/emesis 11/2/0, infections 2/1/0, diarrhea 14/2/0, and stomatitis 6/1/1. One patient developed hemolytic-uremic syndrome. Conclusions: The tumor control rate (PR + NC) of 70% was comparable to established chemotherapy regimens, while median overall survival was promising. Toxicity was mild, allowing the treatment especially for elderly patients and on outpatient basis.

Phase II Study of a Weekly 24-Hour Infusion with 5-Fluorouracil and Simultaneous Sodium – Folinic Acid in the First-Line Treatment of Metastatic Colorectal Cancer

Background: A weekly continuous 24-hour infusion therapy with 5-fluorouracil (5-FU) and calcium – folinic acid (CA-FA) was shown to be an effective first-line treatment in advanced metastatic colorectal cancer. Sodium – folinic acid (S-FA) is a new formulation which, in contrast to CA-FA allows the simultaneous i.v. administration in combination with 5-FU in one pump. Patients and Methods: From 1997 to 1998, 51 patients [median age 60 (range 24–77) years; 38 male, 13 female] with metastatic colorectal cancer were recruited in 5 centers to receive weekly 24-hour infusions of 5-FU (2,600 mg/m2) and S-FA (500 mg/m2) dissolved in one pump for 6 weeks as first-line treatment. The treatment cycle was repeated after a 2-week rest period. Results: 1,178 administrations (median 24, range 3–54) were performed during the study. Out of 51 patients (median follow-up 20.2 months), 2 (3.9%) achieved complete remission (CR), 17 (33.3%) partial remission (PR), and 21 (41.2%) no change (NC). Progressive disease (PD) was observed in 11/51 (21.6%) patients, including 6 patients who did not complete the first cycle. Median time to tumor progression (TTP) was 8.5 months (95% CI: 5.8–11.3). 32/51 (62.7%) patients survived for more than 1 year, the median survival was reached at 16.5 months (95%CI: 10.2–22.8). Among major toxicities, NCICTC grade III/IV diarrhea occurred in 13/51 (25.4%), grade III hand-foot syndrome in 6/51 (11.7%) patients. Grade III/IV stomatitis was observed in 4/51 (7.8%), cardiac toxicity occurred in 2/51 patients (3.9%). Conclusion: Similar to conventional 24-hour 5-FU + CA-FA treatment, the combination with S-FA induced 37.2% objective responses with moderate toxicity. However, TTP seems favorable and the administration of S-FA is convenient, while saving costs and time for the patient in outpatient units.

Efficacy and tolerability of an aminopterin-albumin conjugate in tumor-bearing rats.

The antifolate aminopterin (AMPT) was developed before methotrexate (MTX), but was not clinically established or generally used due its increased toxicity compared to MTX. Recently, we reported on the increased metabolism of albumin conjugates such as methotrexate–albumin (MTX–SA) in malignant tumors and the feasibility of using albumin as a carrier for drug targeting. Consequently, AMPT was covalently bound to serum albumin (AMPT–SA) at a 1:1 molar ratio. Biodistribution, tolerability and efficacy of this novel conjugate were studied in Walker-256 (W-256) carcinoma-bearing rats. As compared to native albumin, the same biodistribution and plasma clearance were found for AMPT–SA, which achieved 20.1% tumor uptake (estimated uptake per g tumor 6.4%) within 24 h after i.v. administration in rats. In a randomized study, AMPT–SA, repeatedly i.v. injected, was compared with low-molecular-weight AMPT. Depending on the molar concentration, the maximum tolerated dose (MTD) of AMPT covalently bound to SA was twice that of unbound AMPT (three repeated injections of 1.0 mg AMPT–SA/kg body weight versus three repeated injections of 0.5 mg AMPT/kg body weight;p =0.0006). Efficacy was studied at the level of the MTD and MTD/2, and demonstrated that AMPT–SA was significantly more active. At the MTD/2 in W-256 carinoma-bearing rats, AMPT–SA achieved a 100% volume reduction and an optimal volume reduction during treatment/control (T/C) of 8.3% compared to a 53% volume reduction of AMPT and a T/C of 16.5% (p =0.032). Tumor relapses were reduced and occurred later in the AMPT–SA group (two tumor recurrences for AMPT–SA versus seven for AMPT;p =0.05). In this comparative study, the AMPT–SA conjugate showed high antitumor activity in vivo and a favorable toxicity compared to low-molecular-weight AMPT. These effects are attributed to the albumin carrier which seems to be an effective tool for selective tumor drug targeting.