In Spanish: Expediente de Registro de Medicamento

As Ron says, ERM is quite commonly found as the abbreviation of Evaluación de Riesgo Microbiológico (Microbiological Risk Assessment), but that just doesn't seem relevant here: there's no obvious microbiological angle in your report or indeed other CECMED reports on the Internet that have this reference code (of which there are a number).

I base my answer on the following document, which is the 2010 issue (no. 2) of Investigaciones ININ, the digital journal of the Cuban Instituto de Investigaciones de Normalización. It is in a contribution entitled "Modelo básico para diseñar e implantar Sistemas de Gestión de la Calidad integrando NC ISO 9001:2008 con las Buenas Prácticas de Fabricación farmacéuticas cubanas", which includes tables showing the documents required by Cuba's own BPP [Buenas Prácticas de Producción] Regulación 16/2006 and how they correspond to the ISO standard mentioned. In the list of Cuban documents corresponding to "Procedimientos para el control de los productos no conformes", we find "Expediente de registro de medicamento".
http://www.inin.cubaindustria.cu/docs/Boletin-Investigacione...

Although I do not have a document to prove that ERM in CECMED reports stands for this, I think it is very probable. It makes perfect sense in context, and describes exactly what CECMED is doing: registering drugs or medicines.

In a report of a Cuban clinical trial of "IFN alfa-2b recombinante en esclerosis multiple recurrente-remitente", for example, we find the following entries:
"Fecha de la autorización de inicio por Agencia reguladora: 1995-03-23 18:00
Número de referencia en la agencia reguladora: ERM:176/95
[...]
Agencia que registró el producto: CECMED"
http://registroclinico.sld.cu/ensayos/.2008-04-08.165143-11

By the way, it is quite clear that the number after the slash is the year, as you suspected. The number before the slash is presumably the index number, corresponding to how many such "expedientes" CECMED had issued that year.