T cell therapy against cancer: A predictive diffuse-interface mathematical model informed by pre-clinical studies.

T cell therapy has become a new therapeutic opportunity against solid cancers. Predicting T cell behaviour and efficacy would help therapy optimization and clinical implementation. In this work, we model responsiveness of mouse prostate adenocarcinoma to T cell-based therapies. The mathematical model is based on a Cahn-Hilliard diffuse interface description of the tumour, coupled with Keller-Segel type equations describing immune components dynamics. The model is fed by pre-clinical magnetic resonance imaging data describing anatomical features of prostate adenocarcinoma developed in the context of the Transgenic Adenocarcinoma of the Mouse Prostate model. We perform computational simulations based on the finite element method to describe tumor growth dynamics in relation to local T cells concentrations. We report that when we include in the model the possibility to activate tumor-associated vessels and by that increase the number of T cells within the tumor mass, the model predicts higher therapeutic effects (tumor regression) shortly after therapy administration. The simulated results are found in agreement with reported experimental data. Thus, this diffuse-interface mathematical model well predicts T cell behavior in vivo and represents a proof-of-concept for the role such predictive strategies may play in optimization of immunotherapy against cancer.

Dendritic cell functional improvement in a preclinical model of lentiviral-mediated gene therapy for Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is a rare X-linked primary immunodeficiency caused by the defective expression of the WAS protein (WASP) in hematopoietic cells. It has been shown that dendritic cells (DCs) are functionally impaired in WAS patients and was(-/-) mice. We have previously demonstrated the efficacy and safety of a murine model of WAS gene therapy (GT), using stem cells transduced with a lentiviral vector (LV). The aim of this study was to investigate whether GT can correct DC defects in was(-/-) mice. As DCs expressing WASP were detected in the secondary lymphoid organs of the treated mice, we tested the in vitro and in vivo function of bone marrow-derived DCs (BMDCs). The BMDCs showed efficient in vitro uptake of latex beads and Salmonella typhimurium. When BMDCs from the treated mice (GT BMDCs) and the was(-/-) mice were injected into wild-type hosts, we found a higher number of cells that had migrated to the draining lymph nodes compared with mice injected with was(-/-) BMDCs. Finally, we found that ovalbumin (OVA)-pulsed GT BMDCs or vaccination of GT mice with anti-DEC205 OVA fusion protein can efficiently induce antigen-specific T-cell activation in vivo. These findings show that WAS GT significantly improves DC function, thus adding new evidence of the preclinical efficacy of LV-mediated WAS GT.

Ultrasensitive in-house reverse transcription-competitive PCR for quantitation of HIV-1 RNA in plasma.

An ultrasensitive version of an 'in-house' reverse transcription-competitive polymerase chain reaction assay described previously for quantitation of human immunodeficiency virus type 1 (HIV-1) RNA in plasma was developed. The increase in sensitivity from 400 to 50 HIV-1 RNA copies/ml was achieved by pelleting virus particles from 1.8 ml plasma by centrifugation prior to RNA extraction, modifying competitor DNA structure and amounts, and redesigning primers. Quantitation of HIV-1 RNA in 130 samples tested previously by the standard assay showed that the two procedures yield comparable results (mean absolute difference, 0.26+/-0.20 log) and that the ultrasensitive version detects HIV-1 RNA below the threshold of sensitivity of the standard method. The ultrasensitive 'in-house assay' and the reference QUANTIPLEX HIV-1 RNA 3.0 had the same sensitivity and gave equivalent results (mean absolute difference, 0.19+/-0.11 log), as shown by parallel blinded testing of 47 plasma samples. Titration experiments with reconstructed plasma samples allowed the determination of a dynamic range of 50-500000 HIV-1 RNA copies/ml for the 'in-house' system. The interassay coefficient of variation for samples nominally containing 200, 4000 and 80000 HIV-1 RNA copies/ml were 33.4, 22.9 and 38.2%, respectively. The performance, turnaround time, and cost-effectiveness of this system make it suitable for medium-scale clinical application.

Antiretroviral resistance mutations in human immunodeficiency virus type 1 reverse transcriptase and protease from paired cerebrospinal fluid and plasma samples.

Twenty-four adults infected with human immunodeficiency virus type 1 (HIV-1) with central nervous system symptoms were studied for antiretroviral resistance mutations in HIV-1 RNA obtained from paired cerebrospinal fluid (CSF) and plasma samples. Paired sequences were obtained from 21 and 13 patients for reverse transcriptase (RT) and for protease, respectively. Mutations conferring resistance to the RT inhibitors zidovudine, lamivudine, or nevirapine were detected in 14 patients, including 11 pretreated and 3 drug-naive subjects. The mutation patterns in the 2 compartments were different in most patients. Genotypic resistance to protease inhibitors was detected in both plasma and CSF from 1 patient treated with multiple protease inhibitors. However, accessory protease inhibitor resistance mutations at polymorphic sites were different in plasma and CSF in several patients. Partially independent evolution of viral quasispecies occurs in plasma and CSF, raising the possibility that compartmentalization of drug resistance may affect response to antiretroviral treatment.

Analysis of the HIV-1 nef gene in five intravenous drug users with long-term nonprogressive HIV-1 infection in Italy.

Great variability in the course of human immunodeficiency virus type 1 (HIV-1) infection results from a complex interplay between host and virus factors. Some of the patients with prolonged nonprogressive infection have been reported to harbor virus variants with gross deletions in the accessory nef gene that has been implicated in in vivo pathogenicity in simian and mouse models. To investigate the role of nef-deleted HIV-1 in long-term nonprogressor (LTNP) drug addicts in Italy the nef sequence from proviral DNA was analyzed from five LTNPs and five rapid progressor controls. Only small (2-12 amino acids) in-frame deletions and insertions were detected in the N-terminal polymorphic and variable regions obtained from three LTNPs and one rapid progressor. There was no evidence of premature termination of the Nef protein and all of the identified functional motifs were well conserved in both groups. Phylogenetic analysis showed interdigitation of nef sequences obtained from LTNPs and rapid progressors. The nef sequence of one LTNP, however, diverged significantly from those of the other patients. Availability of two additional blood DNA samples obtained previously from this subject allowed to detect evolution of nef at 14-17 years of HIV-1 infection, including progressive deletions. Although alterations of nef may be relatively frequent and continue to evolve in LTNPs, this study of a small number of patients does not indicate that gross deletions or loss of functional motifs play a major role in delaying or halting disease progression in infected drug abusers in Italy.

Development and significance of the HIV-1 reverse transcriptase M184V mutation during combination therapy with lamivudine, zidovudine, and protease inhibitors.

To analyze the emergence and role of the lamivudine (3TC)-selected HIV-1 reverse transcriptase (RT) M184V mutation under triple therapy, we performed a retrospective study of 40 nucleoside RT inhibitor-pretreated and 16 drug-naive patients who were switched to combined treatment with zidovudine (ZDV) plus 3TC plus a protease inhibitor (PI). Plasma viral load and pol genotype were analyzed at baseline and after 24 and 48 weeks of combination therapy. Emergence of the M184V RT mutation at week 48 was detected in 3 of 16 (18.7%) initially drug-naive subjects as opposed to 21 of 40 (52.5%) ZDV-pretreated patients. Multivariate logistic analysis detected HIV-1 RNA load at week 24 as the best predictor of subsequent selection of the M184V mutant (p = .0121). Among ZDV-resistant study subjects at week 24 (n = 17), those with mutant RT M184V codon had a more favorable HIV-1 RNA slope than those with wild-type RT 184M codon (p = .0551). This trend was observed, although in a less evident manner, even in pretreated ZDV-sensitive patients. These findings suggest that development of the 3TC-resistance M184V mutation under triple therapy with 3TC, ZDV, and a PI may have unexpected beneficial effects in vivo in addition to those associated with resensitization of ZDV-resistant virus to ZDV.

Genotypic resistance to zidovudine as a predictor of failure of subsequent therapy with human immunodeficiency virus type-1 nucleoside reverse-transcriptase inhibitors.

To define factors predictive of failure to respond to nucleoside reverse-transcriptase inhibitors in human immunodeficiency virus type-1 (HIV-1)-infected subjects pretreated with zidovudine (ZDV), three groups of subjects shifted to double therapy with ZDV plus didanosine (ddI, n = 13), zalcitabine (ddC, n = 14), or lamivudine (3TC, n = 12) were retrospectively evaluated, with respect to addition of the second NRTI, at week 0 and week 24. Factors considered included duration of ZDV pretreatment, CD4+ cell counts, plasma HIV-1 RNA load, peripheral blood mononuclear cell HIV-1 DNA load, and HIV-1 DNA genotypic resistance to nucleoside reverse-transcriptase inhibitors. The three groups were well matched for baseline characteristics and did not differ significantly in virological and immunological response to the different combination treatments. Drug-specific resistance mutations were selected in more than half the cases by 3TC, but not by ddI and ddC. Low-level and substantial genotypic resistance to ZDV was detected 13 (33.3%) and in 19 (48.7%) patients at baseline, respectively, and evolved through week 24 in several patients. When subjects were divided into responders and nonresponders to the second nucleoside reverse-transcriptase inhibitor on the basis of a decrease of more than 0.5 log10 (n = 15) or less than 0.5 log10 (n = 21) in HIV-1 RNA, respectively, baseline genotypic ZDV resistance was the only independent predictor of failure in a logistic regression model (P = 0.003 or P = 0.024, depending on whether low-level resistance was considered or not, respectively). Thus, selection of ZDV resistance mutations may impair subsequent use of different nucleoside reverse-transcriptase inhibitor compounds.

Clinical evaluation of an in-house reverse transcription-competitive PCR for quantitation of human immunodeficiency virus type 1 RNA in plasma.

An in-house reverse transcription (RT)-competitive PCR (RT-cPCR) for the quantitation of human immunodeficiency virus type 1 (HIV-1) RNA in plasma samples was developed and validated. The procedure involves (i) extraction of RNA with spin columns, (ii) ready-to-use bead-mediated RT, (iii) competitive PCR in a microtiter plate, (iv) agarose gel electrophoresis of the reaction products, and (v) densitometric analysis of the digitized image of the gel. Quadruplicate tests and dilution studies showed that the sensitivity and intertest coefficient of variability of the RT-cPCR are comparable to those of the reference AMPLICOR HIV-1 MONITOR test. The results obtained by the two assays with a panel of 45 clinical samples were in good agreement (mean difference, 0.36 +/- 0.25 log units). Analysis of 1,982 clinical samples by the in-house RT-cPCR yielded the typical range of plasma HIV-1 RNA levels with the expected inverse correlation between CD4 counts and HIV-1 RNA titers. In addition, testing of plasma from 36 subjects at weeks 0 and 4 with respect to the time of initiation of protease inhibitor therapy detected a significant decrease in HIV-1 viremia. The mean reduction in the HIV-1 RNA level was 0.914 log unit for those receiving saquinavir (P = 0.0210), 1.584 log units for those receiving indinavir (P = 0.0047), and 1.904 log units for those receiving ritonavir (P < 0.0001). The in-house RT-cPCR assay is simple to develop and perform and allows quantitation of HIV-1 RNA in 100 to 200 samples per operator per week. Since the cost is 1/8 to 1/10 of those of reference commercial assays, this procedure could be conveniently used in medium-scale laboratories.

Antiretroviral therapy with protease inhibitors in human immunodeficiency virus type 1- and human herpesvirus 8-coinfected patients.

Human herpesvirus 8 (HHV-8) is believed to play a role in the pathogenesis of Kaposi's sarcoma (KS) and possibly in other proliferative disorders often associated with human immunodeficiency virus type 1 (HIV-1) infection. Recent case reports have indicated resolution of KS and clearance of HHV-8 DNA from peripheral blood mononuclear cells (PBMC) in HIV-1-infected subjects following highly effective antiretroviral therapy, including HIV-1 protease inhibitors (PI), suggesting a possible activity for these compounds on HHV-8 replication. In the present study, the time course of PBMC HHV-8 DNA levels, plasma HIV-1 RNA load, and CD4+ T-cell counts were followed up in six coinfected subjects (four with and two without KS) under antiretroviral therapy with PI. A specific anti-HHV-8 role for PI was not consistently found, since fluctuation of HHV-8 viral load over time appeared to be independent of treatment. Nevertheless, our data support the hypothesis that KS patients may significantly benefit from PI therapy as an indirect consequence of partial restoration of immune functions following effective anti-HIV-1 combination therapy.

Evaluation of cell-free and cell-associated peripheral blood human immunodeficiency virus type 1 RNA response to antiretroviral therapy.

Plasma human immunodeficiency virus (HIV) type 1 RNA load is the reference marker for response to antiretroviral therapy. To compare peripheral blood mononuclear cell (PBMC)-associated and plasma HIV-1 RNA response to treatment, HIV-1 RNA was quantified by reverse transcription-competitive polymerase chain reaction in 20 patients at 0, 12, and 24 weeks following addition of saquinavir to their treatment regimens. HIV-1 RNA was undetectable in 15 plasma samples but in only 2 PBMC samples (P=.002) and CD4 cell counts correlated more with PBMC than with plasma HIV-1 RNA load. Changes in HIV-1 RNA load in PBMC and in plasma were correlated, and the decrease was higher in plasma than in PBMC at weeks 12 (P=.002) and 24 (P=.017). Moreover, PBMC, but not plasma HIV-1 load, at week 12 was predictive of HIV-1 RNA levels at week 24 in both plasma (P=.004) and PBMC (P<. 001). Thus, measurement of PBMC HIV-1 RNA may be useful during antiretroviral therapy.

Long-read direct infrared sequencing of crude PCR products for prediction of resistance to HIV-1 reverse transcriptase and protease inhibitors.

Patients infected with human immunodeficiency virus type 1 (HIV-1) are being treated with a number of different combinations of antiretroviral compounds that target the essential viral enzymes reverse transcriptase and protease. Different sets of HIV-1 mutations that confer drug resistance have been well defined; they allow reasonable prediction of the drug sensitivity pattern from analysis of the HIV-1 genotype in vivo. Since periodical monitoring of genotypic resistance is expected to improve clinical management in a large number of infected patients, practical and cost-effective methods are highly desirable to set at least medium-scale sequencing in clinical diagnostic settings. We present a complete protocol for direct sequencing of HIV-1 reverse transcriptase and protease-coding regions. Features making the system amenable to routine clinical use include: 1. Highly robust presequencing steps (plasma RNA extraction, reverse transcription, and nested PCR); 2. Direct use of the crude unpurified PCR product as the sequencing template; and 3. Use of infrared-labeled sequencing primers consistently allowing long reads, thus obviating the need for sequencing of both DNA strands.

Detection of human herpesviruses 6 and 7 in heart transplant recipients by a multiplex polymerase chain reaction method.

In order to evaluate the possible reactivation of human herpesviruses 6 (HHV-6) and 7 (HHV-7) after heart transplantation, buffy-coat and plasma specimens from 21 transplant patients and 56 healthy blood donors were examined for HHV-6 and HHV-7 DNA by polymerase chain reaction. Human herpesvirus 6 and HHV-7 infection or reactivation has been suggested to play a role in cytomegalovirus disease progression in renal transplant recipients. In the present study, however, no significant difference in the prevalence of HHV-6 and HHV-7 was found between the immunosuppressed and the healthy population; moreover, no viral reactivation was found in the heart transplant recipients.

Evaluation of the presence of 2-LTR HIV-1 unintegrated DNA as a simple molecular predictor of disease progression.

In a preliminary cross-sectional analysis of 109 human immunodeficiency virus type 1 (HIV-1)-infected subjects the presence of 2-long terminal repeat (LTR) unintegrated circular HIV-1 DNA in peripheral blood mononuclear cells (PBMC) was found to be associated with both symptomatic infection (P = 0.0037) and low CD4 counts (P = 0.0004). To investigate the prognostic significance of the presence of 2-LTR HIV-1 DNA, a subset of 23 2-LTR-negative and 25 2-LTR-positive asymptomatic individuals were followed up for 12-24 months. The two groups did not differ in terms of baseline CD4 counts, zidovudine (ZDV) therapy, and duration of HIV-1 infection. Longitudinal analysis of CD4 values did not indicate a significantly different CD4 outcome between the two groups. However, when only ZDV-treated subjects were considered, a significant (P = 0.042) decrease in CD4 counts was found at month 24 with respect to baseline in 2-LTR-positive (n = 12) but not in 2-LTR-negative (n = 11) patients. Moreover, when > 40% CD4 loss from baseline and/or development of CDC stage B or C symptoms were considered as indicators of disease progression, there was a significantly higher number of events in the whole 2-LTR-positive group than in the whole 2-LTR-negative group (P = 0.0197 at month 12, P = 0.0299 at month 18, P = 0.0373 at month 24). Thus, the presence of 2-LTR HIV-1 DNA in PBMC merits further investigation as a simple, qualitative, molecular predictor of disease progression and decreased response to antiretroviral therapy.

Zidovudine resistance mutations and human immunodeficiency virus type 1 DNA burden: longitudinal evaluation of six patients under treatment.

Zidovudine (ZDV) is by far the most widely used drug to counteract human immunodeficiency virus type 1 (HIV-1) infection, both in monotherapy and in combination therapy regimens. However, the majority of patients under prolonged ZDV therapy have been shown to harbour HIV-1 mutant genomes displaying reduced sensitivity to the drug in vitro. In order to investigate the pathogenic role of in vitro resistance to ZDV, six HIV-1-infected ZDV-treated subjects were evaluated longitudinally (mean follow-up 28.5 months, range 12-39 months) for HIV-1 DNA load in peripheral blood mononuclear cells (PBMC) and for the presence of HIV-1 pol gene mutations responsible for ZDV resistance. Quantitation of HIV-1 DNA was performed by competitive polymerase chain reaction (cPCR) and the pol genotype was determined by direct sequencing of PCR products. All of the six patients developed one or more of the HIV-1 pol mutations known to confer resistance to ZDV in vitro (Met41-->Leu, Asp67-->Asn, Lys70-->Arg, Thr215-->Phe/Tyr, Lys219-->Gln/Glu). A temporal association was found between HIV-1 DNA burden and the level of ZDV resistance, as predicted on the basis of the pol genotype (genotypic resistance). Both virus load and ZDV resistance were inversely correlated with CD4+ cell counts. These results are compatible with a direct in vivo pathogenetic role for pol gene mutations shown to be involved in resistance to ZDV in vitro. Monitoring the degree of genotypic resistance to ZDV and to other antiretroviral drugs should be considered in designing protocols for the management of treated patients.

Concordance between polymerase chain reaction and antibody detection in the diagnosis of human immunodeficiency virus type 1 infection.

A highly sensitive nested polymerase chain reaction (PCR) protocol was used to detect human immunodeficiency virus type 1 (HIV-1) DNA in peripheral blood mononuclear cells from 271 HIV-1-seropositive patients, 240 HIV-1-seronegative subjects at increased risk for HIV-1 infection, 51 serologically indeterminate individuals, and 120 healthy blood donors. PCR was carried out in a multiplex nested configuration with pol and env region primer sets. HIV-1 DNA was detected in all of the HIV-1 seropositive patients. In contrast, HIV-1 DNA was not detected in any of the either seronegative or serologically indeterminate subjects. Only one of 37 seronegative regular sexual partners of HIV-1-infected patients who were followed longitudinally was found to seroconvert to HIV-1. However, HIV-1 DNA and antibody results were concordant in the four samples obtained from this subject prior to and after seroconversion. These results show an excellent concordance between HIV-1 DNA and antibody detection for diagnosis of HIV-1 infection and suggest that long-term HIV-1 infection in the absence of detectable antibody is likely to occur at a very low frequency.

Increased reliability of selective PCR by using additionally mutated primers and a commercial Taq DNA polymerase enhancer.

A reliable selective PCR procedure that combines the use of additionally mutated primers with the specificity-enhancing properties of a commercial preparation (Perfect Match, Stratagene) is described. The human immunodeficiency virus type 1 pol gene point mutations known to confer in vitro resistance to azidothymidine were examined as a model for optimization of the assay. The usual strategy of deliberately introducing an additional mismatch 1 residue from the 3' end in the wild-type and mutant primers did not allow reproducible discrimination between wild-type and mutant target sequences. Addition of minimal amounts of Perfect Match to the same PCR mixtures resulted in a significantly enlarged range of selective annealing temperatures, providing a valuable and cost-effective means for reliable detection of known mutations by selective PCR.

Low human immunodeficiency virus type 1 (HIV-1) DNA burden as a major cause for failure to detect HIV-1 DNA in clinical specimens by PCR.

To determine the sensitivity of a nested PCR procedure for detecting human immunodeficiency virus type 1 DNA in clinical specimens, 553 peripheral blood mononuclear cell samples obtained from 268 human immunodeficiency virus type 1-seropositive subjects were assayed by use of two independent primer sets for each sample. Overall, 1,088 of 1,106 (98.37%) reactions were positive. Investigation of the negative reactions showed that a low viral burden in some infected subjects, rather than primer-template mismatches, was the primary cause for the false-negative PCR results.