# Biological relapse in multiple myeloma: Outcome and treatment strategies in a Spanish real‐world setting

## TL;DR

This study examines when to start treatment for multiple myeloma relapse in Spain, finding that starting treatment at clinical relapse rather than biological relapse improves patient outcomes.

## Contribution

The study provides real-world evidence on treatment timing in multiple myeloma relapse and identifies factors influencing progression-free survival.

## Key findings

- Starting treatment at clinical relapse was associated with longer progression-free survival compared to biological relapse.
- Relapse from complete remission and first relapse correlated with longer time to progression.
- Physicians tend to initiate treatment earlier in patients with poor prognosis features.

## Abstract

Recommendations regarding the best time to start treatment in patients with relapsed/refractory multiple myeloma (RRMM) after biological relapse/progression (BR) are unclear. This observational, prospective, multicenter registry aimed to evaluate the impact on time to progression (TTP) of treatment initiation at BR versus at symptomatic clinical relapse (ClinR) based on the Spanish routine practice in adult patients with RRMM. Patients had two or less previous treatment lines and at least one previous partial response. Baseline characteristics and treatment outcomes were recorded, and survival was analyzed. Of 225 patients, 110 were treated at BR (TxBR group) and 115 at ClinR (TxClinR group) according to the investigators' criteria. The proportion of patients with higher ECOG, previous noncomplete remission (CR), and second relapse were significantly higher in the TxBR group compared to the TxClinR group. TheTxClinR group showed improved outcomes, including TTP, compared to the TxBR group. Progression‐free survival increased in the TxClinR group (56.2 months) compared to the TxBR group (32.5 months) (p = 0.0137), and median overall survival also increased (p = 0.0897). Median TTP was significantly longer in patients relapsing from a CR (50.4 months) and in their first relapse (38.7 months) compared to those relapsing from a non‐CR response (32.9 months) and in their second relapse (25.2 months). Physicians seemed to start treatment earlier in RRMM patients with poor prognosis features. Previous responses to anti‐MM treatment and the number of prior treatment lines were identified as prognosis factors, whereby relapse from CR and first relapse were associated with a longer time to progression.