NEJM original articles

Background. Maridebart cafraglutide (known as MariTide) is a long-acting peptide-antibody conjugate that combines glucagon-like peptide-1 receptor agonism and glucose-dependent insulinotropic polypeptide receptor antagonism and that is intended for the treatment of obesity.

Methods. We conducted a phase 2, double-blind, randomized, placebo-controlled, dose-ranging trial that included 11 groups as two cohorts. Participants with obesity (obesity cohort) were randomly assigned in a 3:3:3:2:2:2:3 ratio to receive maridebart cafraglutide subcutaneously at a dose of 140, 280, or 420 mg every 4 weeks without dose escalation; 420 mg every 8 weeks without dose escalation; 420 mg every 4 weeks with 4-week dose escalation; 420 mg every 4 weeks with 12-week dose escalation; or placebo. Participants with obesity with type 2 diabetes (obesity-diabetes cohort) were randomly assigned in a 1:1:1:1 ratio to receive maridebart cafraglutide at a dose of 140, 280, or 420 mg every 4 weeks (all without dose escalation) or placebo. The primary end point was the percent change in body weight from baseline to week 52.

Results. We enrolled 592 participants. In the obesity cohort (465 participants; female sex, 63%; mean age, 47.9 years; mean body-mass index [BMI, the weight in kilograms divided by the square of the height in meters], 37.9), the mean percent change in body weight from baseline to week 52 on the basis of the treatment policy estimand (intention-to-treat approach) ranged from -12.3% (95% confidence interval [CI], -15.0 to -9.7) to -16.2% (95% CI, -18.9 to -13.5) with maridebart cafraglutide, as compared with -2.5% (95% CI, -4.2 to -0.7) with placebo. In the obesity-diabetes cohort (127 participants; female sex, 42%; mean age, 55.1 years; mean BMI, 36.5), the mean percent change in body weight from baseline to week 52 on the basis of the treatment policy estimand ranged from -8.4% (95% CI, -11.0 to -5.7) to -12.3% (95% CI, -15.3 to -9.2) with maridebart cafraglutide, as compared with -1.7% (95% CI, -2.9 to -0.6) with placebo. The mean change in the glycated hemoglobin level on the basis of the treatment policy estimand in this cohort was -1.2 to -1.6 percentage points in the maridebart cafraglutide groups and 0.1 percentage points in the placebo group. Gastrointestinal adverse events were common with maridebart cafraglutide, although less frequent with dose escalation and a lower starting dose. No unexpected safety signals emerged.

Conclusions. In this phase 2 trial, once-monthly maridebart cafraglutide resulted in substantial weight reduction in participants with obesity with or without type 2 diabetes. (Funded by Amgen; ClinicalTrials.gov number, NCT05669599.).

Background. Zimislecel is an allogeneic stem cell-derived islet-cell therapy. Data on the safety and efficacy of zimislecel in persons with type 1 diabetes are needed.

Methods. We conducted a phase 1-2 study of zimislecel in persons with type 1 diabetes. In part A, participants received a half dose of zimislecel (0.4 × 10⁹ cells) as a single infusion into the portal vein, with an option for a second half dose within 2 years. In parts B and C, participants received a full dose of zimislecel (0.8 × 10⁹ cells) as a single infusion. All the participants also received glucocorticoid-free immunosuppressive therapy. The primary end point in part A was safety. The primary end point in part C was freedom from severe hypoglycemic events during days 90 through 365, with a glycated hemoglobin level of less than 7% or a decrease of at least 1 percentage point from baseline in the glycated hemoglobin level at one or more time points between days 180 and 365. Secondary end points in part C included safety and insulin independence between days 180 and 365. Assessment of the primary and secondary end points in part C involved the participants who received the full dose of zimislecel as a single infusion in part B or C. Detection of serum C-peptide during a 4-hour mixed-meal tolerance test was used to assess engraftment and islet function. All the analyses were interim and not prespecified.

Results. A total of 14 participants (2 in part A and 12 in parts B and C) completed at least 12 months of follow-up and were included in the analyses. C-peptide was undetectable at baseline in all 14 participants. After zimislecel infusion, all the participants had engraftment and islet function, as evidenced by the detection of C-peptide. Neutropenia was the most common serious adverse event, occurring in 3 participants. Two deaths occurred - one caused by cryptococcal meningitis and one by severe dementia with agitation owing to the progression of preexisting neurocognitive impairment. All 12 participants in parts B and C were free of severe hypoglycemic events and had a glycated hemoglobin level of less than 7%; these participants spent more than 70% of the time in the target glucose range (70 to 180 mg per deciliter). Ten of the 12 participants (83%) had insulin independence and were not using exogenous insulin at day 365.

Conclusions. The results of this small, short-term study involving persons with type 1 diabetes support the hypothesis that zimislecel can restore physiologic islet function, warranting further clinical investigation. (Funded by Vertex Pharmaceuticals; VX-880-101 FORWARD ClinicalTrials.gov number, NCT04786262.).

Background. Controversy persists regarding the appropriate duration of therapy with benzathine penicillin G in persons with early (i.e., primary, secondary, or early latent) syphilis (Treponema pallidum infection).

Methods. In a multicenter, randomized, controlled, noninferiority trial, we assigned persons who had early syphilis, with or without human immunodeficiency virus (HIV) infection, to receive intramuscular injections of benzathine penicillin G in a one-time dose of 2.4 million units or in doses of 2.4 million units administered at three successive weekly intervals. The primary end point was seroreversion to nonreactive status or a decrease in the rapid plasma reagin titer by two or more dilutions at 6 months, referred to here as a serologic response (noninferiority margin, 10 percentage points). A key secondary end point was a serologic response within subgroups defined according to HIV status, also assessed in a noninferiority analysis.

Results. A total of 249 persons with early syphilis were enrolled. Most participants were men (97%), 62% were Black, and 153 (61%) were living with HIV infection. The distribution according to syphilis stage was 19% with primary syphilis, 47% with secondary syphilis, and 33% with early latent syphilis. The percentage of participants with a serologic response at 6 months was 76% (95% confidence interval [CI], 68 to 82) in the single-dose group and 70% (95% CI, 61 to 77) in the three-dose group (difference, -6 percentage points; 90% CI, -15 to 3, indicating noninferiority). No clinical relapse or treatment failure occurred in either group. In the one-dose group, a serologic response at 6 months was observed in 76% of participants who had HIV infection and 76% of those who did not, and in the three-dose group, a serologic response at 6 months was observed in 71% of participants who had HIV infection and 70% of those who did not. Most participants in each group had local injection-site pain and tenderness with treatment (76% with a single dose and 85% with three doses).

Conclusions. Treatment with one dose of 2.4 million units of benzathine penicillin G was noninferior to treatment with three doses with regard to serologic response 6 months after treatment. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT03637660.).

Background. Heparin-induced thrombocytopenia (HIT) is an immune-mediated platelet disorder caused by antibodies that target complexes of platelet factor 4 (PF4) and heparin. HIT has been characterized as a polyclonal immune response; however, studies of other rare anti-PF4 disorders have identified clonally restricted antibodies.

Methods. In this study, we investigated the clonality of pathogenic HIT antibodies. Antibodies against PF4-heparin were affinity-purified with the use of PF4-heparin beads from serum samples obtained from nine patients with clinically and serologically confirmed HIT. Antibody clonality was assessed by means of immunofixation electrophoresis and mass spectrometry. Antibody binding to PF4 was evaluated by an enzyme immunoassay, and functional platelet activation was evaluated with the use of a P-selectin expression assay. HIT antibody epitopes were mapped in two patients with the use of a PF4 mutant library.

Results. Serum samples from all nine patients with HIT were positive for platelet-activating antibodies against PF4-heparin by enzyme immunoassay, as well as the P-selectin expression assay, and six samples (67%) had a monoclonal antibody detectable by immunofixation electrophoresis. The affinity-purified antibodies against PF4-heparin from all nine samples activated platelets in the P-selectin expression assay, and mass spectrometry showed monoclonality. After affinity purification, antibody-depleted serum samples lost binding activity in the enzyme immunoassay and functional activity in the P-selectin expression assay, which confirmed the removal of the pathogenic antibodies. The epitopes on PF4 targeted by anti-PF4-heparin antibodies from serum samples were the same as those targeted by the affinity-purified monoclonal antibodies.

Conclusions. The pathogenic antibodies in all nine patients with HIT were found to be monoclonal. This finding provides insight into the pathogenesis of HIT and has implications for improved diagnostics and targeted therapeutics. (Funded by the Canadian Institutes of Health Research and the National Institutes of Health.).

The need to suppress a patient's immune system after the transplantation of allogeneic cells is associated with wide-ranging side effects. We report the outcomes of transplantation of genetically modified allogeneic donor islet cells into a man with long-standing type 1 diabetes. We used clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 12b (Cas12b) editing and lentiviral transduction to genetically edit the cells to avoid rejection; the cells were then transplanted into the participant's forearm muscle. He did not receive any immunosuppressive drugs and, at 12 weeks after transplantation, showed no immune response against the gene-edited cells. C-peptide measurements showed stable and glucose-responsive insulin secretion. A total of four adverse events occurred, none of which were serious or related to the study drug. (Funded by the Leona M. and Harry B. Helmsley Charitable Trust; EudraCT number, 2023-507988-19-00; ClinicalTrials.gov number, NCT06239636.).