Recovery of Ocular Events with Longer-Term Follow-up in the DREAMMM-2 Study of Single-Agent Belantamab Mafodotin (Belamaf) in Patients with Relapsed or Refractory Multiple Myeloma (RRMM)

Introduction: Patients with heavily pretreated RRMM have a poor prognosis (median overall survival [OS]: 6–9 months) and a need for novel, well-tolerated treatments that induce lasting responses (Gandhi Leukemia 2019; Chari NEJM 2019). Belamaf (GSK2857916) is a first-in-class, B-cell maturation antigen–targeting, antibody–drug conjugate (ADC) containing monomethyl auristatin F (MMAF). In DREAMM-2 (NCT03525678), patients with heavily pretreated RRMM who responded to single-agent belamaf maintained deep and durable responses at 13-month follow-up (median OS: >13 months) with a manageable safety profile (Lonial ASCO 2020, Poster 436). Consistent with other MMAF-containing ADCs, ocular events were common (Farooq et al. Ophthal Ther 2020). These events included keratopathy (microcyst-like epithelial changes [MECs]: an eye exam finding with/without symptoms), best-corrected visual acuity (BCVA) changes, and symptoms (blurred vision and dry eye). Longer-term recovery data will help inform management strategies.

Methods: In DREAMM-2, eye exams were conducted at baseline and prior to each dose in patients received single-agent belamaf (2.5 or 3.4 mg/kg Q3W) and included a corneal exam and assessment of BCVA change from baseline (Snellen visual acuity [VA]). Dose modifications (delays/reductions) were permitted to manage these events. The corneal events were graded per the Keratopathy and Visual Acuity (KVA) scale, which combined corneal exam findings and BCVA changes from baseline. Dose modifications were determined based on the most severe KVA scale grade. These events were followed until recovery, defined as any Grade 1 exam findings/no exam findings, and ≤1-line decline in Snellen VA compared with baseline. A change to a BCVA 20/50 or worse (ie, limiting driving ability) in the better-seeing eye (in patients with BCVA better than 20/50 at baseline) was considered one definition of clinically meaningful VA decrease. Recovery of these events was defined as BCVA improvement to better than 20/50 (better-seeing eye). We report ocular event outcomes for patients receiving belamaf 2.5 mg/kg (recommended dose for future clinical development) from a 13-month follow-up post-hoc analysis.

Results: In patients receiving single-agent belamaf 2.5 mg/kg, 72% (68/95) experienced a treatment-related eye exam finding of keratopathy (MECs) (Farooq Ophthal Ther 2020). Fewer patients (56%; 53/95) had symptoms (eg, blurred vision or dry eye) and/or a ≥2-line BCVA decline (better-seeing eye). Treatment discontinuations due to ocular events were rare (3% [3/95] total; 1% [1/95] each due to keratopathy [MECs], blurred vision, and reduced BCVA (Farooq Ophthal Ther 2020).

In patients with keratopathy (MEC) events Grade ≥2 per KVA, 48% (29/60) had >1 event. The first event recovered in 77% (46/60; Table; Farooq Ophthal Ther 2020). At last follow-up, 48% (29/60) had documented recovery of their most recent event (Farooq Ophthal Ther 2020). In patients with unrecovered events at last follow-up, 45% (14/31) are receiving treatment or in follow-up. The remaining 55% (17/31) are no longer in follow-up (9 died; 4 withdrew from study; 4 lost to follow-up). 84% (37/44) of patients with Grade 3/4 events were improving or had recovered events at last follow-up.

Seventeen (18%) patients had a clinically meaningful BCVA decline, with no reports of complete permanent vision loss (Farooq Ophthal Ther 2020). Of these patients, 76% (13/17) had 1 event and 24% (4/17) had 2 events (no patients had >2 events). 82% (14/17) had recovery of their first event and 82% (14/17) had recovery at last follow-up (Farooq Ophthal Ther 2020). Of the remaining 3 patients with unrecovered events, 1 patient is receiving treatment and 2 patients are no longer in follow-up (1 died due to disease progression; 1 withdrew from study).

Conclusions: Though keratopathy (MECs) were frequently observed on eye exam, the majority of patients did not experience a clinically meaningful BCVA decline, and events rarely led to treatment discontinuation. The first keratopathy (MEC) event or clinically meaningful BCVA decline recovered in the majority of patients with events. In this ongoing study, patients are being followed for recovery. Based on experience, it is anticipated these events will likely recover over time.

Funding: GSK (205678); drug linker technology licensed from Seattle Genetics; mAb produced using POTELLIGENT Technology licensed from BioWa.