Randomized, placebo-controlled Phase II trial of heat-killed Mycobacterium vaccae (Immodulon batch) formulated as an oral pill (V7)

AIM

A 1-month Phase II trial was conducted in 41 patients with pulmonary TB who were randomized into treatment (n = 20) and placebo (n = 21) arms to investigate the safety and efficacy of an orally-administered therapeutic TB vaccine (V7) containing 10 µg heat-killed Mycobacterium vaccae provided by Immodulon Therapeutics Ltd (London, UK).

MATERIALS & METHODS

Both arms received conventional anti-TB therapy administered along with a daily pill of V7 or placebo. The subject population had four categories of TB: drug-sensitive TB; retreated TB; drug-resistant TB; and TB with HIV distributed in V7 and placebo arms at 9:4:7:6 and 14:1:6:8 ratios, respectively.

RESULTS

The mycobacterial clearance in sputum smears was observed in 72.2% (p < 0.0001) and 19% (p = 0.03) of patients on V7 and placebo, respectively. The average weight accrual among V7 recipients was 2.6 kg (p = 0.002) versus -0.2 kg (p = 0.69) in the control group. Except reduction in fever and increased lymphocyte counts, the changes in other secondary end points, such as hemoglobin, erythrocyte sedimentation rate and leukocyte counts, were not statistically different, although the proportion of patients responding favorably to V7 was invariably higher compared with placebo (p = 0.002). In control patients, no difference from baseline levels was noted except decreased hemoglobin content (p = 0.02).

CONCLUSION

Oral M. vaccae was safe and has potential as an adjunct immunotherapy, targeting mucosal immunity, to improve efficacy and shorten treatment duration of TB chemotherapy.

Targeting multidrug-resistant tuberculosis (MDR-TB) by therapeutic vaccines

Tuberculosis (TB) has scourged humankind for millennia, and latent infection affects nearly one-third of today's world population. The emergence of multidrug-resistant (MDR)-TB is a major global threat and reflects treatment failure of drug-sensitive disease. MDR-TB management is a burden for patients and society; success rates are unacceptably low with prolonged treatment duration. Mycobacterium tuberculosis (Mtb) possesses the ability to transform into a dormant state in which it can persist in the face of antimicrobial treatment and host defense. This sub-population of persisters is largely responsible for lengthy and difficult treatment. Targeting persistent bacilli could eventually improve the treatment success rate (currently 50-65 %) and shorten duration of treatment. A subset of therapies in the pipeline, termed therapeutic vaccines, use the host immune response to attack Mtb. The historical occurrence of an exacerbated host response has resulted in a negative perception of therapeutic vaccines. Thus, a renewed concept of immunotherapy is needed. We review current perspectives of immunotherapy in MDR-TB based on the knowledge of TB immunology and briefly discuss the profiles of several therapeutic vaccine products.

Adjunct immune therapy of first-diagnosed TB, relapsed TB, treatment-failed TB, multidrug-resistant TB and TB/HIV

Aim: To evaluate the effect of an adjunct immunotherapy in randomized double-blind, placebo-controlled Phase IIb trial involving 123 TB patients. Methods: Patients were randomly allocated into two arms: one (n = 62) received a once-daily pill of V-5 Immunitor™ (V5) and the other (control; n= 61) received placebo for 30 days in addition to first- or second-line TB drugs administered under directly observed therapy. The subjects in V5 and placebo arms had first-diagnosed, relapsed, treatment-failed and multidrug-resistant TB at ratios of 17:21:11:13 and 20:19:14:8, respectively; among them, ten and seven had HIV coinfection, respectively. Results: After 1 month, 55 out of 62 patients (88.7%) became sputum smear-negative in the V5 arm (p < 0.0001), whereas in the placebo group, nine out of 61 (14.8%) had converted. The conversion rate among V5 recipients was similar, regardless of whether TB was drug-sensitive, drug-resistant or with HIV. V5 downregulated TB-associated inflammation, as shown by the normalization of elevated leukocyte counts (8.7 vs 6.3 × 10 9/l; p < 0.0001) and decreased erythrocyte sedimentation rate (22.8 vs 12.6 mm/h; p < 0.0001), whereas among placebo recipients, changes were smaller (8.9 vs 8.2 × 10 9/l and 25.1 vs 19.9 mm/h). Thirty three (54.1%) placebo patients gained on average 0.8 kg (p = 0.0002); by contrast, 57 (91.9%) out of 62 patients in the V5 group gained a mean weight of 2.9 kg (p < 0.0001). No adverse side effects or reactivation of TB were seen at any time. Conclusion: V5 is safe and effective as an immune adjunct to chemotherapy for TB and can potentially reduce the treatment duration down to 1 month.

Immunological basis for the introduction of immunotherapy with Mycobacterium vaccae into the routine treatment of TB

An account is given of the immunological investigations carried out in Rosario (Argentina) to identify suitable methods for the assessment of the efficacy of immunotherapy for TB. Some of these were then applied to three small studies: one of a single injected dose of heat-killed, borate-buffered Mycobacterium vaccae administered early in treatment, another of three such doses administered at monthly intervals from the start of treatment, and the third of ten oral doses at frequent intervals throughout short-course chemotherapy. All three displayed better clearance of bacilli from the sputum, faster improvement in clinical symptoms, better radiological resolution of lesions and a return of most immunological parameters towards those of healthy persons. In principle, the immune change achieved is an increase in Th1 mechanisms, notably IL-2 and -12 with downregulation of the tissue damaging aspects of Th2. As an addition to chemotherapy for drug-susceptible or drug-resistant TB, with or without concomitant HIV infection, this immunotherapy offers a safe and effective improvement.

Phase IIb randomized trial of adjunct immunotherapy in patients with first-diagnosed tuberculosis, relapsed and multi-drug-resistant (MDR) TB

Placebo-controlled, randomized, phase 2b trial was conducted in 34 adults comprising 18 first-diagnosed (52.9%), 6 relapsed (17.6%), and 10 MDR-TB (29.4%) cases to investigate the safety and efficacy of an oral immune adjunct (V5). The immunotherapy (N = 24) and placebo (N = 10) arms received once-daily tablet of V5 or placebo for one month in addition to conventional anti-TB therapy (ATT) administered under directly observed therapy (DOT).

The enlarged liver, total bilirubin, erythrocyte sedimentation rate, lymphocyte and leukocyte counts improved significantly in V5 recipients (P = 0.002; 0.03; 8.3E-007; 2.8E-005; and 0.002) but remained statistically unchanged in the placebo group (P = 0.68; 0.96; 0.61; 0.91; and 0.43 respectively). The changes in hemoglobin and ALT levels in both treatment arms were not significant. The body weight increased in all V5-treated patients by an average 3.5 ± 1.8 kg (P = 2.3E-009), while 6 out of 10 patients on placebo gained mean 0.9 ± 0.9 kg (P = 0.01). Mycobacterial clearance in sputum smears was observed in 78.3% and 0% of patients on V5 and placebo (P = 0.009). The conversion rate in V5-receiving subjects with MDR-TB (87.5%) seemed to be higher than in first-diagnosed TB (61.5%) but the difference was not significant (P = 0.62). Scoring of sputum bacillary load (range 3-0) at baseline and post-treatment revealed score reduction in 23 out of 24 (95.8%) V5 recipients (from mean/median 2.2/3 to 0.3/0; P = 6E-010) but only in 1 out of 10 (10%) patients on placebo (1.9/1.5 vs. 1.8/1; P = 0.34). No adverse effects or TB reactivation were seen at any time during follow-up. V5 is safe as an immune adjunct to chemotherapeutic management of TB and can shorten substantially the duration of treatment.

Adjunct oral immunotherapy in patients with re-treated, multidrug-resistant or HIV-coinfected TB

This Phase IIb, placebo-controlled study involved 55 TB patients treated with anti-TB therapy. They were divided into two groups, matched by age, gender, baseline bodyweight and clinical manifestations: one group (n = 27) received a once-daily V-5 Immunitor (V5) immunotherapy pill and the other (n = 28) received placebo. Only one (3.7%) and three (10.7%) subjects in V5 and placebo arms, respectively had first-diagnosed, drug-sensitive TB; the remaining patients had re-treated TB, multidrug-resistant TB or HIV-TB coinfection. After 1 month, 26 out of 27 patients (96.3%) became sputum smear negative in the V5 group (p < 0.0000001), whereas seven out of 28 (25%) in the placebo group had converted (p = 0.005). V5 contributed to the downregulation of TB-associated inflammation, as shown by normalization of high leukocyte counts, erythrocyte sedimentation rate and faster defervescence than controls. Patients in both arms experienced an increase in the levels of hemoglobin corresponding to 128.9 ± 17.6 versus 133.1 ± 14.7 g/l (p = 0.03) and 112.6 ± 14 versus 117 ± 11.7 g/l (p = 0.03) in V5 and placebo arms, respectively. In total, 19 out of 28 placebo patients (67.9%) gained, on average, 1.07 kg (59.1 ± 10 vs 60.1 ± 10.4 kg; p = 0.003). By contrast, all patients in the V5 group gained weight with mean 3.4 kg (59.7 ± 8 vs 63.1 ± 9 kg; p = 5.7E-007). Clinical symptoms improved among all patients in V5 arm, while 28.6% of patients on placebo reported satisfactory results (p = 0.007). No adverse or side effects attributable to V5 were seen at any time. Further studies are needed to gauge the extent of the benefits of V5 as safe and effective adjunct immunotherapy for TB.